Skip to main content

Full text of "A Treatise on chemistry v. 3, 1884"

See other formats


Google 



This is a digital copy of a book that was preserved for generations on library shelves before it was carefully scanned by Google as part of a project 

to make the world's books discoverable online. 

It has survived long enough for the copyright to expire and the book to enter the public domain. A public domain book is one that was never subject 

to copyright or whose legal copyright term has expired. Whether a book is in the public domain may vary country to country. Public domain books 

are our gateways to the past, representing a wealth of history, culture and knowledge that's often difficult to discover. 

Marks, notations and other maiginalia present in the original volume will appear in this file - a reminder of this book's long journey from the 

publisher to a library and finally to you. 

Usage guidelines 

Google is proud to partner with libraries to digitize public domain materials and make them widely accessible. Public domain books belong to the 
public and we are merely their custodians. Nevertheless, this work is expensive, so in order to keep providing tliis resource, we liave taken steps to 
prevent abuse by commercial parties, including placing technical restrictions on automated querying. 
We also ask that you: 

+ Make non-commercial use of the files We designed Google Book Search for use by individuals, and we request that you use these files for 
personal, non-commercial purposes. 

+ Refrain fivm automated querying Do not send automated queries of any sort to Google's system: If you are conducting research on machine 
translation, optical character recognition or other areas where access to a large amount of text is helpful, please contact us. We encourage the 
use of public domain materials for these purposes and may be able to help. 

+ Maintain attributionTht GoogXt "watermark" you see on each file is essential for in forming people about this project and helping them find 
additional materials through Google Book Search. Please do not remove it. 

+ Keep it legal Whatever your use, remember that you are responsible for ensuring that what you are doing is legal. Do not assume that just 
because we believe a book is in the public domain for users in the United States, that the work is also in the public domain for users in other 
countries. Whether a book is still in copyright varies from country to country, and we can't offer guidance on whether any specific use of 
any specific book is allowed. Please do not assume that a book's appearance in Google Book Search means it can be used in any manner 
anywhere in the world. Copyright infringement liabili^ can be quite severe. 

About Google Book Search 

Google's mission is to organize the world's information and to make it universally accessible and useful. Google Book Search helps readers 
discover the world's books while helping authors and publishers reach new audiences. You can search through the full text of this book on the web 

at |http: //books .google .com/I 



A TREATISE ON CHEMISTEY. 






TOL in. — PART I. 



TREATISE ON CHEMISTRY. 



HY 



H. E. ^SCOE F.R.S. and C. SCHORLEMMER F.R.S. 

PROFR«IK>Rll or f'HFMIflTRY IN THF. VICTORIA UNIVKRfllTY, OWKNS COLLROC, MAKCHBtTKR. 



VOLUME III. 
THE CHEMISTRY OF THE HYDROCARBONS AND THEIR DERIVATIVES, 



OR 



ORGANIC CHEMISTRY. 

PART I. 



''Chymia, alicu Alchemia et Spagirica, est ara corpora vel mixta, vel eompoiita^ 
irZ aggregala etiam in privcipia mm resoJrevdi, a\U ex principiis in talia 
combinandi"^BTABh, 1723. 



I^onbon : 
MACMILLAN AND CO. 

1881. 

[ The Jtight of Translation and Jttprodvdion is PMcrved,] 



• • 



• • • 









• • • 






• • • 

• • • • 



I/>KD011 : 

R. Clay, Sous, and Taylor, 

BREAD STREET HILL. 



\ '.I 



CONTENTS. 



HfSTOIlICAL iNTRoDltTION 

Early Ideas on Organic Chemistry 
Lavoisier's Researclies 
Ik^rzelius' Investigations 
C*onipound Radicals . 
Dumas* Theory of Substitutions . 
Dumas' Theory of Chemical Types 
isolation of the Radicals . . . 
Theories of Types and Radic^als . 
Gerhardt's Theory of Types 
Williamson's Views 
Theory of Mixed Types 
Definitions of Organic Chemistry 
Hvdrocarhons and their Derivatives 
Homologous Series 



PA«»K 

3 
5 

9 
11 
15 
16 
19 
22 
24 
27 
30 
33 
37 
39 



ILTIMATE Organic Analysis. 

Livoisier^s Method of Analysis . 
Saussure, Th^nard, and Berthollet's Method 
Gay-Lussac and Thenard's Method 
Berzelius' Metho<l .... 

Liebig's Method 

Gas Combustion Furnaces . 

Combustion in Current of Oxygen 

Combustion of Nitrogenous Bodies 

Combustion of Bodies containing Sulphur 

Organic Analysis by means of Platinum 

Determination of Nitrogen . 

Will and Varrentrapp's Method . 

Li«-big's Relative Method . 

Bunsen's Relative Method . 

Dumas' Absolute Method 

Simpson's Method 

Determination of Chlorine, Bromine, and lodin; 

Determination of Sulphur . 

Determination of Phosphorus 

Determination of other Elements 

Determination of Oxygen . 



40 
41 
43 
43 
45 
48 



55 

58 

50 

60 

64 

60 

67 

68 

70 

71 

75 

78 

79 

79 



501 1 1 



VI 



CONTENTS, 



Catxjulation of Analyses 
Percentage Composition 
Oaloulation of Formula* 



PAOR 

80 
80 
82 



Drtermination of VAi'oru Density 
Dumas* Method .... 
Gay-Lu8sae*8 Method . 
Hofmann's Method 
Victor Meyer's Methods 



84 
84 
87 
89 
94 



Dbtermination of Moleculab Formula 
Empirical and Rational Fonnulae 
Constitutional Formulae 
Saturated and Non-Saturated Compounds 



103 
112 
114 
117 



Isomerism 



. 119 



Classification of the Carbon Compounds . 



. 128 



Hydeocarbons of the Paraffin Series 
Constitution of the Paraffins 
Preparation of the Paraffins 
Application of the Paraffins 
Origin of Petroleum . 
American Oil-wells 



130 
135 
136 
140 
142 
145 



Fractional Distillation 
DifltilUtion of Mixtures 



147 
153 



The Compounds of the Monad Alcohol Radicals 
Alcohols and Ethereal Salts, nature of 
Haloid and Simple and Mixed Ethers . 
Sulphine Compounds and Snlphoniu Acids 
Compound Ammonias 
Hydrazine Compounds 
Cyanides of Alcohol Radicals 
Cyanates and Isocvanates . 
Compound Ureas, or Carbamides, &c. 
Nit ro- Paraffins .... 
Compounds of Alcohol Radicals with Metals 



154 
154 
155 
158 
159 
161 
162 
163 
165 
167 
168 



The Alcohols and their Derivatives 
Primary Alcohols and Fatty Acids 
Primary Alcohols .... 

Aldehydes ...... 

Haloid Com]K>unds of tlie Acid Radicals 
Ethereal Salts, or Com|K)nnd Ethers . 



169 
169 
171 
172 
173 
174 



CONTENTS. 



vii 



PAGE 

Auhydrides, or Oxides of the Acid Radicals 176 

Tbio- Anhydrides, or Sulphides of the Acid Radicals . .176 

Amides 177 

Substitution-Products of the Fatty Acids 178 

Synthesis of the Primaiit Alcohols and the FAriY Acidh . .179 

Liebeu and Rossi's Method 180 

Fraukland and Duppa's Method 180 



Se«-oni)ary Alcohols and Ketoneh 



182 



Teutiauy Au'oholh 



186 



The Methyl Guoir 

Metlinne, or Methyl Hydride 
Methyl Alcohol .... 
Methyl Oxide, or Di-Methyl Ether 
Ethereal Salts of Methyl . 
Sulphur Compounds of Methyl . 
Selenium Compounds of Methyl 
Tellurium Compounds of Methyl 
Nitrogen Bases of Methyl . 
Cyanogen Compounds of Methyl 
^itro-Compounds of Methyl 
Phosphorus Compounds of Methyl 
Ancnic Compounds of Methyl 
Compounds of Methyl with Antimony 
(.'ompounds of Methyl with Boron 
Compounds of Methyl with Silicon 
Metallic Compounds of Methyl . 
Other Derivatives of Methyl 



190 
190 
194 
200 
202 
212 
216 
217 
218 
224 
227 
229 
2^4 
243 
244 
245 
245 
253 



Thk Formyl Groui" 
Formic Aldehyde 
Formi(? Acid 
Tlie Foniiatcs 



Thk Ethyl Group 

Ethane 

Ethvl Alcohol 

-Ucoholometr}* 

Ethyl Ether, or Ethyl Oxi^le 
The Ethereal Salts of Ethyl, or Ethyl Comiwund 
Sulphur Compounds of Ethyl 
Compounds of Ethyl and Selenium 
Compounds of Ethyl and Tellurium . 
Nitrogen Bases of JSthyl .... 
Cyanogen Comi)ounds of Ethyl . 
Kthylated Ureas 



Ethers 



266 
266 
269 
274 

279 
279 
282 
301 
323 
842 
379 
397 
899 
401 
413 
419 



Vlll 



C'< »NTKNTS. 



Ktlivl Sl*mu•u^bll/i^^o^ .... 
Ktliyliitod lliio-Ureas .... 
Nitn)-Com|iouii«l« of Ethyl . 
rikusphorufl Hasps of Ethyl 
Arst'iiii- Coiiipouuds of Ethyl 
Aiitiuiony Coinpouiids of Ethyl . 
Bisniutli Cnmpouiuls of Ethyl 
Horoii i\)inpoun(l8 of Ethyl 
SiluMtiironipouiKls of Ethyl 
Coitipoundrt of Ethyl with the Mt'talis . 
Acotyl CoinpoiiinN .... 
.Voi-tic AcM ..... 

Till' Atrtato.-?, or th«' Salts and Elhri> nf A« 
Oxidos of Aeetvl .... 

« 

Haloid Conipouiids of Acetyl 
Sulphur Coiiipouinls of Acetyl 
Nitm^iMi Compounds of Acetyl . 
Acptoiiitril ami its Derivatives 
Siih»titiition-l*ro<lm-ts of Acetic Arid . 



VllC 



\ci.l 



VMiK 


. 421 


. 422 


. 423 


. 431 


. 440 


. 443 


. 447 


. 448 


. 45(1 


. 45.1 


. 473 


. 483 


. 496 


. 509 


. 513 


. 515 


517 


. 521 


. 533 



• oMIiilNPS Ci«MAlNINH TllKKE Al»».Ms «iF OaRUuN, or. JIIR TUOI'VI. 

<;k«h r 

rriniary Propyl Alcohol ...... 

I'ropionic AKlehydc and IVopioniv Acid 
StM'omLry Tn'tpyl AIi*ohoI ..... 

Aceti^ni-. or Hiinetlivl Kef on. ... 



548 
548 
556 
563 



< I -Mil 'I'M'.* Ci»NTAiMNii Fun; Atoms of TARnnN, hm thk RrXYL Oinn r 576 

Normal Hiilanc and iN iV-rivativts .577 

riiir.iiy Butyl CoiMiHiuiils . fiSil 

Si. .iTi.l.iry r»iitvH'i>niiHmu«ls .".Sl 

!-»i»*MU.inc and it"* Piriv.itivo'S fi^S 

TriiiMiy l-^!iut\I L'l'iiiimuud- 5S3 

Ttrti.iiy Butyl roiiii>«ninds 5S6 

Th- rmtyri- A id-i 59»^ 

N.v.;::yry! Cotiiihvjti.U 597 



• . V!-.; \: - < iNLviMN.. Five Aii-mn i.f i'Ar.n«'S. im; mr. Prsrvi Kic-ri- 
N«rv \\ r. iitiT:- iTid i!-i l»i ri\ itivi"* ... 

I* •!" T.T.u.- a:ii i*" Pt r;\iitiv»"i 
r-.i .\'.r.>'. Ti ■::.!■« ■U'..'i " 
!*•:: i: !.-.:*. v". M,:J. n.* .\:..i i*^ 1 »• i;\ if;\. - 
Th- r- v: •• • T V '.".ri ■ Ail-. 



M'2 
003 

rtll 
617 
•*17 



• . V. • \;.- t. N. vn:n"- >'.\ Aii'M-s i-F < .VKr.ns. «■!; iiii lUwi «;»;.•;! rt25 

!»•■ . \ iti" a:. : •'•. Iv ::v i*i\. - t\:\i 

>!■ !li\ .-I'-.'.^.v'. M '".ir.. .•, i i:- 1». ii\ »-.\t- *y:M 



CONTENTS. 



IX 



Tetrametliyl Ethane and its Derivatives 
Triniethyl-Ethyl Methane and its Derivatives 
The Hexoic or Caproic Acids • 



Pai;e 
631 
633 
634 



Compounds Contaimxo Seven Atoms of Carbon, or the Heprvr. 

Geoup 631) 

. 639 

. 643 

. 644 

. 646 



Normal Heptane and its Derivatives 
laoiheptane and its Derivatives . 
Triethvl Methane and its Derivatives 
The Heptoic Acids 



CoMPorjcDs CojrrAiN'iNG Eight Atoms of Carbon, or the Octyl Group 650 

Normal Octyl Componnds 650 

Tetraniethvl Butane and its Derivatives 654 

TertLiry Octyl Compounds 655 

Hexiuethy] Ethane 656 

The Octoic Acids 656 



roMPCtuvDs Containing Nine Atoms of Carbon, or the Nonyl Groit 658 
The Nonoic Acids 059 



CoMPorNiiS Containing Tejt Atoms of Carbon, or the Decatyl Giujui* 662 
The Capric, or Decatoic Acids 664 



OiMP<»rND» C<»NTAININC ElE\'EN AtOMS OF CaRBON, OR THE HeNDECATYL 

Group 665 



f'**MP*^r\j»< C«iNTAiNiNf; Twelve Atoms of Carbon, ou thk I)<u»f.(atyl 

Geoup GH7 



♦ "Ml y yvs Containing Thirteen Atoms of Cakiu>n, oii tiik Tuiuk- 

'•%tyl Gnnup 669 



^•'Ui-rsv'y Containing Fourteen Atoms of CAnnoN, ok the Tetra- 

i.F/; An- L Group 669 



*-%:^'sifit Containing Fifteen Atoms of Caijwjn, ok the Penta- 

iiecattl Group 670 



.. Containing Sixteen Atoms of CAKimx, oi: the Hec- 

r* ATVL Group 671 



X CONTENTS. 

PAue 

Compounds Containing Seventeen Atomk of Carbon .... 677 

Compounds Containing Eighteen Atoms of Carbon .... 678 

Co-MPOUNDS Containing from Nineteen to Twenty-four Atoms of 

Carbon 681 

The Waxes 681 

Cioneral Properties of the Fatty Acid.s 684 

Soap 688 



A TREATISE ON CHEMISTRY. 



ORGANIC CHEMISTRY, 



vol- ffl « 



OEGANIO CHEMISTBY, 

OR THE CHEMISTRY OF THE HYDROCARBONS AND THEIR 

DERIVATIVES. 



HISTORICAL INTRODUCTION. 

z Many of the most important chemical facts known to the 
ancients have their place in the Organic portion of our science. 
Thus, for example, the only acid with which the ancients were 
acquainted was an organic substance, viz., vinegar or dilute 
acetic acid, and the name of this body and the idea of acidity 
were expressed by closely related words, of 09, acetus, vinegar ; 
and o^v^i acidus, acid.^ 

Again, the first reagent of any kind which we find described 
is also an organic body, namely the extract of gall-nuts with 
which, as Pliny states, the ancients were accustomed to ascer- 
tain whether verdigris was adulterated with green vitriol. 

The first rude attempts at distillation were also made with 
an organic body, viz., turpentine ; whilst the first salts which 
were artificially prepared were organic ones, being those ob- 
tained by the action of vinegar on the alkalis. The mode 
of preparing soap by the action of fats upon the alkalis was 
also known in early times. In addition to a knowledge of 
the fets and oils, the ancients were acquainted with various 
resins, and colouring matters, as well as with sugar and gum. 
They likewise understood the preparation of wine from 
grape-juice, and certain nations, especially the Egyptians, 
Gauls and Germans, were accustomed to prepare beer from 
nialted grain. 

1 See YoL ii. part i. p. 32. 

B 2 



HISTORICAL INTKODUCTION. 



As the direction in which the science first developed itself 
was that of alchemy^ the object of which was the conversion of 
the baser metals into gold and silver, it is natural that attention 
was in the first place paid rather to the properties of mineral 
substances than to those of organic bodies^ Nevertheless im- 
provements in general chemical processes, especially that of 
distillation, gradually led to the discovery of definite organic 
compounds such as spirit of wine {aqua vita:) and certain of the 
essential oils. The action of heat upon bodies when air is ex- 
cluded was also studied in early times. Thus the products of the 
dry distillation, as we now term this process, of bodies such as 
cream of tartar were investigated, and the action of acids upon 
spirits of wine and other organic substances was likewise examined. 

Later on, towards the sixteenth century, the cultivators of 
this science, as we have seen,^ exhibited activity mainly in two 
directions, in the first place in the prosecution of the branch 
science of metallurgy, and secondly, in the development of iatro- 
chemistry. In these branches, and especially in the latter, it 
was, however, the inorganic division of the science which made 
the most rapid strides, because, in opposition to the practice of 
the old school, the use of metallic preparations as medicines 
was largely introduced. At the same time the study of organic 
compounds, and especially of the active principles of organic 
bodies, was not entirely neglected. Thus during this period 
benzoic acid, succinic acid, wood-vinegar, milk-sugar, and various 
ethers were discovered. 

In the succeeding epoch, when the true function of chemistry 
had become fully recognised, inorganic comix)unds still claimed 
the more immediate attention of chemists, not only because 
they arc more stable than organic bodies, but also because in 
the latter case it had not as yet proved possible, as it had 
in tho case of inorganic bodies, to determine their composition 
by synthesis as well as by analysis. 

a From this period it is that wc may date a distinct separation 
of mineral chemistry from that portion of the science which is 
concerned \\ii\\ the study of substances formed in vegetable 
and animal organisms. For a long time chemical compounds 
were groupttl together according to their jihysical properties, 
and the common names at present in use for many substances 
remind one of this bygone classification. Thus, for instance, 
olivo oil and other vegetable and animal oils were placed 

* Vol. i. p. 8, "lliHtorical lutroductiou.*' 



EARLY IDEAS ON ORGANIC CHEMISTRY. 5 



together with oil of vitriol and with oleum tartari (deliquesced 
carbonate of potash). Alcohol again (spirit of wine) was classed 
with stannic chloride (fuming spirit of Libavius), with ammonia 
(spirit of hartshorn), and with nitric acid (spirit of nitre), &c. 
Common butter wa« placed in the same group as antimony 
trichloride (butter of antimony) and other semi-solid metallic 
chlorides. Colourless solid bodies which were soluble in water, 
and possessed a peculiar taste were all classed together as salts, 
even sugar being placed in this group. 

3 In the year 1675 Nicolas Lemery published his Cours de 
Chf/mic, In this work the aim of chemistry is defined to be 
a knowledge of the various substances "qui se rencontrent 
dans un mixte," understanding by this term all growing 
or increasing natural products. Lemery distinguished these 
bf>lies as mineral, vegetable, and animal products. In the first 
group he placed the metals, minerals, earths, and stones ; in the 
second, plants, resins, the different kinds of gums, fungi, fniits, 
acids, juices, flowers, mosses, manna, and honey; and under 
the third head he described the various parts of animal bodies. 

Although L(5mery*s system of classification was generally 
accepted, the founders of the phlogistic theory endeavoured to 
show that the observed diflferences depended on a variation in 
the composition of the bodies classed under each head. Thus 
Becher in 1669 had argued that the same elements occur in 
the three natural kingdoms, but thut they are combined together 
in a simpler manner in mineral substances than they are in 
vegetable and Animal bodies. Stahl, on the other hand, asserted 
in 1702, that in vegetable as well as in animal substances the 
watery and combustible principles predominate, and that these 
make their appearance when such an organic substance is heated 
out of contact with air, water and combustible charcoal being 
formed. 

At this time, as well as during the preceding period, the 
investigation of organic compounds was carried on mainly with a 
view either to the preparation of medicines, or to the improve- 
ment of technical processes, such as that of dyeing. Only 
towards the close of the phlogistic period did organic chemistry 
begin to make real progress, and it is from this time forward 
that the scientific investigation of organic bodies can be said 
to have commenced. 

4 The early ideas of van Helmont and afterwards of Stahl, 
that all organic substances can be resolved by the action of 



HISTORICAL INTRODUCTION. 



heat into their ultimate constituents, viz., aqueous and com- 
bustible principles, were successfully combated by Boyle, who, 
in the Sceptical Chemist (1661), proved that this is not the case, 
inasmuch as the application of heat leads to diflferent results 
according as air is permitted to have access or not, and that the 
various residues thus obtained in no way merit a uniform de- 
signation. The general reception of Boyle's views was slow but 
sure. Still it was not until Lavoisier's discovery in 1775 of the 
composition of carbon dioxide, and Cavendish's determination 
of that of water, that the fact of the existence of carbon and 
hydrogen in alcohol was ascertained (1784). 

5 Amongst the early organic researches of a truly scientific 
character those of Scheele deserve the first mention, for he 
either discovered nearly all the most important vegetable 
acids, or suggested methods for their discrimination. Thus, 
he showed that the acid from lemons differs from that from 
grapes, whilst that contained in apples differs again from 
both of these. He proved that a fourth distinct acid is 
found in wood -sorrel, and pointed out that this can be 
obtained artificially by heating sugar with nitric acid. Ho 
likewise obtained gallic acid from gall-nuts, uric acid from 
urine, and lactic acid from sour cow's milk. By the oxidation 
of milk-sugar he prepared mucic acid, a substance altogether 
different from the acid obtained from cane-sugar. In the pre- 
paration of these and other acids Scheele employed methods 
many of which are in use at the present day. Scheele also 
showed that fatty oils and the solid fats contain the common 
principle glycerin, termed by him the sweet spirit of oils. This, 
ho says, is connected with sugar not only on account of its sweet 
taste, but also because, like sugar, it is oxidized to oxalic acid 
by nitric acid. 

Scheeles friend Bergman also assisted the progress of 
organic chemistry, whilst Rouelle who distinguished himself 
by researches on tho hitherto neglected division of animal 
chemistry, discovered urea and hippuric acid. 

6 Investigations such as these drew general attention to 
the subject of organic chemistry, and Lavoisier having estab- 
lished the true principle upon which the process of com- 
bustion depends, turned his mind to this interesting branch 
of the science, and ascertained the ultimate composition of 
certain organic compounds. He came to the conclusion that 
vegetable bodies are chiefly composed of carbon, hydrogen, and 



LAVOISIER'S RESEARCHES. 



oxygen, whilst the compounds of the animal kingdom contain 
in addition to these elements, nitrogen and not unfrequently 
pliosphorus.^ 

The Lavoisierian system of chemistry was essentially the 
chemistry of oxygen and its compounds, and hence attention 
was naturally directed to the question whether a given com- 
pound is capable of combining, like an element, with oxygen, 
or whether it was already combined with this element. To 
that portion of a substance which combines with oxygen, 
Lavoisier, at the suggestion of Guyton de Morveau, gave the 
name of la base or le radical. This might either be an elemen- 
tary substance, such as carbon, " le radical de Tacide carbonique," 
or a compound, such as, '* le radical oxalique, tartarique," &c. 

Respecting the difference between organic and inorganic 
compounds, he states that the oxidizableor acid-forming radicals 
of the mineral kingdom are. almost always simple ; those of the 
vegetable and especially of the animal kingdom are however 
generally composed of two substances, carbon and hydrogen, 
and these frequently contain nitrogen as well, and some- 
times phosphorus.* 

The observation that the elements can form different oxides 
led to the supposition that this might likewise be the case 
with organic radicals. Thus for example sugar was considered 
to be a neutral oxide, "d*un radical hydro-carboneux," whilst 
oxalic acid was supposed to be its higher oxide. 

Amongst his more important investigations in the domain of 
organic chemistry Lavoisier's research on fermentation deserves 
especially to be mentioned, not only because he was the first 
to point out that sugar is decomposed into carbonic acid and 
alcohol, but especially because, in connection with this particular 
reaction, he for the first time enunciated the principle which 
underlies the whole of our science, viz., that the weight of the 
products of any chemical change is equal to the sum of the 
weights of the materials taking part in that change, and hence 
that all chemical decompositions may be expressed by equations, 
the truth of which can be ascertained by the analysis of the 
original compound, and controlled by that of the products of 
decomposition. 

On this point Lavoisier's own words may be quoted : " We 
may consider the substances submitted to fermentation and the 



* Lavoisier's Elements of ChemUtry (1787), Kerr's Translation, pp. 17S, 174. 

* Ibid, p. 261. 



8 niSTOniCAL INTRODUCTION. 



products resulting from that operation as forming an algebraic 
equation ; and, by successively supposing each of the elements in 
this equation unknown, we can calculate their values in succes- 
sion, and then verify our experiments by calculation and our 
calculations by experiment, reciprocally. I have often success- 
fully employed this method for correcting the first results of my 
experiments, and so to direct me in the proper road for repeating 
them to advantage." ^ 

It must, however, be especially borne in mind that Lavoisier 
did not distinguish organic chemistry as a special branch of tho 
science; still less did he, as has been stated, define this portion 
of chemistry as the chemistry of compound radicals.^ Thus for 
example he arranged all the acids together, dividing them like 
Lemery into mineral, vegetable, and animal. His more im- 
mediate followers also adopted this course, and it was at that 
time only occasionally that we find organic bodies classed 
together in a group. 

7 By degrees, as substances common to both the animal and 
the vegetable world were discovered, the distinction between 
animal and vegetable chemistry disappeared, and the consequent 
fusion, widening the area covered by the general term organic, 
gradually led to a distinct separation into Inorganic and Organic 
chemistry. At the same time no exact limit could be said 
to exist between these two divisions of tho science. One 
reason for this was that several compounds were found to exist 
which from their origin must be considered as organic, but which 
yielded on analysis results proving tliat they exactly obey the 
laws of constant and multiple proportion, laws supposed at that 
time to apply only to compounds bcl-^nging to the mineral king- 
dom. In the majority of instances, on the other hand, organic 
bodies appeared not to obey these laws. 

8 For the purpose of obtaining more satisfactory informa- 
tion on this question, Berzelius, in 1814, proposed to investigate 
the composition of such substances more accurately than had 
hitherto been done. That this was much needed is clear when 
we remember that Proust, so late as 1803, stated that acetic 
acid contained nitrogen, and that Dalton changed his formula 
for alcohol from 2 C -f H 4- O in 1803, to 3 C 4- H in 1810. 

With this view Berzelius improved the processes of organic 
analysis, and then ascertained that all organic compounds, 

* Layoisier, Elements, p. 107. 

' Kopp, Entwickclung dcr Lhcmic in dcr naiercm Zcit, p. 521. 



THE INVESTIGATIONS OF BERZELIUa 



although in most cases possessing a somewhat complicated 
composition, obey the laws of constant and multiple pro- 
portions applicable to inorganic compounds. Agreeing with 
the views of Lavoisier, Berzelius explained the difference 
existing between these two great divisions by stating that 
whilst in inorganic nature every oxidized compound contains 
a simple radical, organic bodies consist of oxides of compound 
radicals. In the case of vegetable substances the radical usually 
consists of carbon and hydrogen, whilst in the case of animal 
substances it consists of carbon, hydrogen, and nitrogen.* 

9 Berzelius, however, did not experimentally investigate these 
compound radicals, although the discovery of cyanogen by 
Gay-Lussac in 1815 served as an excellent example of the 
existence of such a series of bodies. The cyanogen com- 
pounds were, however, at that time almost invariably placed 
amongst inorganic bodies, for, as has been stated, the limit 
between inorganic and organic chemistry was not clearly defined. 
Thus Gmelin in 1817, in the first edition of his great handbook, 
states that a clear distinction ought to be made between the 
two classes of compounds, but that this distinction can be more 
readily felt than strictly defined. He laid down that Inorganic 
compounds are characterised by their binary constitution, the 
most simple consisting of compounds of two elements, a basic 
oxide or an acid (that is what we now term an acid-forming 
oxide), which can again unite to form a binary compound of a 
higher order, namely, a salt. Organic bodies, on the other hand, 
are at least ternary compounds, or are composed of three simple 
substances, generally united together in less simple proportions 
than is the case in inorganic bodies. Accordingly, Gmelin 
describes marsh gas, defiant gas, cyanogen, &c., in the inorganic 
portion of his handbook. He likewise adds that organic com- 
pounds cannot, like inorganic compounds, be artificially built up 
from their elements. 

About the same time Berzelius again enforced this distinction 
between inorganic and organic bodies, asserting, like Gmelin, 
that the first could, whilst the latter could not, bo artificially 
produced. He assumed that in living structures the elements 
obey totally different laws from those which regulate the form- 
ation of compounds belonging to the inanimate world. Thus 
ia the Introduction to his TraitS ^ he says : " Dans la nature 

1 Berzeliws Lehrbueh, 2te Atifl. 1817, vii. 6ii. 
« Ibid, French edition, 1840. v. i>. 1. 




10 HISTORICAL INTRODUCTION. 

vivante les (Elements paraissent obeir k des lois tout autres 
que dans la nature inorganique ; les produita (j[ui resultent 
de Taction reciproque do ces <51^ments, diflf^rent done de ceux 
que nous priJsente la nature inorganique." Organic bodies were 
thus believed to be the special product of the so-called vital 
force. He admits that the bodies occurring in nature may be 
converted into oth^r organic compounds by chemical decom- 
positions, but none can be built up from their elements. 

10 In the year 1828 came Wohler's memorable discovery of 
the artificial formation of urea. Cyanate of ammonia, which was 
considered to be a truly inorganic compound, is easily converted 
without change of composition into urea, a product of animal 
life. This first artificial production of a body hitherto only pro- 
duced within the animal organism was however incomplete, for 
up to that time the cyanogen compounds had not been prepared 
from their elements. Again, this formation remained for a long 
time the only one of its kind, and the belief in the existence of 
a peculiar vital force still retained a firm footing. Besides, it 
was believed that urea, a substance so easily decomposed 
into carbon dioxide and ammonia, and moreover only ex- 
creted by the animal bcxly, must be looked upon as standing 
half way between organic and inorganic compounds, and it 
was thought that it would still remain impossible to pre- 
pare artificially any of the other more complicated organic 
substances. 

At the present day the belief in a special vital force has 
ceased to encumber scientific progress. We now know that the 
same laws of combination regulate the formation of chemical 
compounds both in animate and in inanimate nature. So soon 
as the constitution of any product of the organic worJd has 
been satisfactorily ascertained we look forward with confidence 
to its artificial j)reparation. 

11 A modification of the early theory concerning the com- 
position of organic compounds, by which they were supposed to 
consist of the aqueous and the combustible principles, and to 
which allusion has boon made, took place in 1815, inconsequence 
of the experiments of Gay-Lussac, who found that the weight of 
a volume of alcohol vapour is ec^ual to the sum of the weights 
of one volume of aqueous vapour and one of olefiant gas ; one 
volume of other va|>our being equal to one volume of the fii'st 
and two of the latter constituent. At the same time Robiquet 
lUid Colin hu<l shown that hydrochloric ether (ethyl chloride) 



COMPOUND RADICALS. 11 



may be considered to be a compound of hydrochloric acid 
with defiant gas. 

Founded upon this observation Dumas and BoulJay^ pro- 
posed a theory according to which many derivatives of alcohol 
may be considered to be compounds in which olofiant gas is 
contained, in the same way as ammonia is present in the 
ammoniacal salts. Berzelius,^ who was originally opposed 
to this view, adopted it at a later period, and proposed that 
the name iEtherin should be given to olefiant gas, C^S^. The 
following table is taken from Dumas and Boullay's memoir, 
the formulae being however altered in accordance with the 
modem atomic weights: 

llydrochlorate of bicarburctted Amniouia hydrocliloride, NH„ IICl. 

hydrogen, CjH4, HCl. 
Nitrite of bicarburctted hydrogen, Ammonia nitrite, NH3, HNO,. 

Csll4, HNO,. 
Sulphate of bicarburctted hydrogen, Acid ammonia 8ulx)liate, NHg, II^SO^. 

Alcohol, C3H4, H.jO. Aqueous Ammonia, NH3, 11^0. 

tther, (C,HJa, H^O. 

Not only did they apply this system of classification to other 
derivatives of alcohol but they attempted to extend their theory 
to all organic compounds. Although it was found possible to 
arrange a certain number of organic bodies according to this 
system, the aetherin theory did not command general recogni- 
tion, partly because a large number of organic bodies could not 
thus be classed, and partly because, in many instances, facts were 
against the theory. Thus, for example, although alcohol could 
be converted into ether or olefiant gas by the withdrawal of 
the elements of water, it was not possible to obtain this or 
any of the other a;therin compounds by the juxtaposition of 
their supposed proximate constituents, such a synthesis being 
possible in the case of the ammoniacal salts. 

12 The classical research of Liebig and Wohler' on the 
radical of benzoic acid published in 1832 was welcomed by 
Berzelius as the dawn of a new era. 

In this celebrated investigation the authors proved that bitter- 
almond oil, benzoic acid, and a number of compounds obtained 
from these, may all be supposed to contain a group of atoms 
or, as they expressed it, *' zusammengesetzter Grundstoff," or 

^ Ann, Chim, Phj/s, xxxvii. 15. • yinn, Pharm. iii. 286, 

» Ana, Plmrm. iii. 249, 282. 



12 HISTORICAL INTRODUCTION. 




compound radical, to which they gave the name benzoyl, tlie 
termination " yl " being derived from the Greek vXrj, matter. 

It has been already stated that Berzelius, like Lavoisier, con- 
sidered that organic compounds containing oxygen must be 
looked upon as the oxides of hydrocarbon radicals. The radical 
benzoyl, C^H^O, however, contains oxygen, and hence the pre- 
dominating influence which this element had hitherto been 
supposed to exert from this time forward ceased, and oxygen 
was placed on a footing of equality with the other elements. 

The radical theory was now enlarged both by Berzelius and 
Liebig, although neither of them agreed in the special views which 
the other advocated. Whilst both opposed the aitherin theory, 
according to which alcohol and ether must be considered to 
be compounds of olefiant gas and water, Berzelius considered 
the above compounds as oxides of two diflferent radicals, whereas 
Liebig^ in a memoir, properly deemed another pillar of the 
radical theory, showed that both compounds contain the same 
radical for which he proposed the name of dhi/l. Accord- 
ing to his view ether is the oxide, and alcohol the hydrate of 
this oxide. The compounds obtained by the action of acids 
en alcohol he considered to be saline compounds of the base 
ethyl oxide. A similar constitution was ascribed to the other 
alcohols and their derivatives, so that each contains a radical 
which plays a part similar to that played by potassium or any 
other metal in its salts. It is interesting to remember that so 
long ago as the year 1834 Liebig asserted that it would probably 
be found possible to isolate these radicals by the decomposition 
of their chlorides or iodides. 

Alcohols on oxidation yield monobasic acids ; methyl alcohol, 
or wood-spirit, yields formic acid, CHjO,, ethyl alcohol, or 
spirit of wine, being similarly converted into acetic acid, CaH^Oy 
The analogy between these acids and monobasic benzoic acid 
was not far to seek, and thus the existence in these acids of 
the oxygenated radicals CHO and CgHjO was assumed. 

Berzelius, however, took exception to this view and asserted 
that benzoyl, although in many respects acting like a simple 
body, must be regarded as the oxide of the body C^Hj. Like 
other oxides benzoyl can unite with more oxygen to form an 
acid. Hence formic acid contains the radical formyl, CH, and 
acetic acid the radical acetyl, C^Hj. Liebig afterwards adopted 
this view, finding that by this means it became possible to group 

* Ayin, Pharm, ix. 1. 



VIEWS OF DUMAS AND LIEBIG. 13 



a large number of compounds round a common centre. Thus 
he supposed that vinyl chloride (monochlorethene), CgHgCl, 
discovered by Regnault, may be looked upon as acetyl chloride, 
and that aldehyde, CgH^O, (which he prepared about this time), 
as well as acetic acid may be regarded as the hydrates of two 
distinct acetyl oxides.^ In a similar way he considered chloro- 
form (which he had also just discovered) to be the chloride of 
formyl, assuming that it stands to formic acid in the same 
relation as phosphorus trichloride does to phosphorous acid. 

In 1837 Dumas adopted these ideas and in his own name, 
as well as in that of Liebig, explained the formation of so 
large a number of naturally occurring organic compounds from 
so small a number of elements, by the fact that these unite 
together and give rise to various radicals which sometimes play 
the part of chlorine and oxygen, and sometimes that of a 
metal. Radicals such as cyanogen, ethyl, benzoyl, &c., may be 
said to constitute the elementary bodies of organic chemistry, 
their elementary components being only recognised when the 
organic nature of the compound is entirely destroyed. 

The discovery and isolation of these radicals was the task 
which Dumas and Liebig in conjunction with their younger 
colleagues set themselves to perform.^ 

13 The essential idea of the chemical constitution of organic 
compounds conceived by Berzelius was a dualistic electro- 
cliemical one, analogous to that which he upheld in inorganic 
chemistry, the difference being that organic radicals play a 
part similar to that played by the elements in the inorganic 
portion of the science. According to him the radicals are 
divided, like the elements, into electro-positive or base- 
forming, and electro-negative or acid-forming radicals. In the 
former division are classed metals, hydrogen, and the alcohol 
radicals; in the latter the elements of the chlorine group, 
oxygen, benzoyl, &c. 

" By the comparison of the behaviour of inorganic with that 
of organic compounds," says Liebig,^ *'we are led to recognise 

* In order to understand the a\)OYe relations it must be borne in mind that the 
tquiraUrU weights, ir=l, 0=8, (7=6. &c., were then employed in place of the 
atomic weights which we now nsc. We thus have the formulae : water, HO ; 
ether, C4//5O ; alcohol, C^H^O, HO ; aldehyde, GJI^O, HO ; acetic acid, 
f.\H^O^ HO; chloroform, C^HCl^ ; formic acid, C^H^O, HO, In the sequel the 
luc of these old equivalent weights will be indicated by the symbols of the 
clemeuts being printed in italics. 

» Compl. Rend, v. 567, ' Aniu Pliarm. xxv. 3. 



14 IirSTORICAL INTRODUCTION. 




the existence of certain component parts which do not undergo 
alteration in a series of compounds, and can be replaced by 
elementary bodies; of component parts which combine with 
elements to form compounds in which the elements can be 
replaced by others ; of component parts, therefore, which take 
the position of simple bodies and play the part of elements. 
In this way the idea of compound radicals has arisen. 

Hence, we term cyanogen a i*adical — (1) because it is an 
unchanging constituent in a series of compounds ; (2) because 
it may be replaced in these compounds by simple bodies ; and 
(3) because in its compounds with elementary bodies these 
latter can be set free and replaced by their equivalents of other 
simple bodies. Of these three conditions, at least two must be 
fulfilled if the radical is to be considered as a true one. 

This definition of a compound radical is fully accepted at 
the present day. 

14 The new era welcomed by Berzelius thus appeareil to 
open brightly, but these hopes were apparently not destined 
to be realized, for whilst Liebig and Berzelius continued to 
uphold their new views, the latter, indeed, defining organic 
chemistry as the chemistry of compound radicals,^ Dumas put 
forth ideas which appeared to him to be inconsistent with the 
radical theory. Much difficulty had been experienced in ex- 
plaining, according to the radical theory, a large group of 
bodies, examined especially by the French chemists, and ob- 
tained by the action of chlorine on organic compounds. It 
had been noticed that in this reaction hydrogen is expelled, 
chlorine entering into combination, and this in equivalent 
quantities, one atom of chlorine being taken up for every atom 
of hydrogen which the body loses. These observations attracted 
but little attention until the year 1834, when Dumas found that 
hydrogen in oil of turpentine can be replaced atom for atom 
by chlorine, thus : 

CioH„ + CI, = CioHijCl + HCl. 

He considered that these facts are based upon a law of nature, 
to express which he suggested the name of Metalepsy ^ 
(/LicTciXiy^tv, an exchange). By the study of these phenomena 
Dumas arrived at his empirical law of subatitutians,^ namely : 
(1) If the hydrogen contained in a hydrogenized body be 

^ Jiandbuch Org, Chem. 1843, 1. ' Mem. Acad, Scienc. xv. 548. 

• Joitrn. de, Pharm. mai, 1834. 



THEORY OF SUBSTITUTIONS. 15 



withdrawn by the action of chlorine, bromine, iodine or oxygen, 
for every atom of the first, one atom of the elements of the 
chlorine group or half an atom of oxygen is substituted.^ 

(2) If the compound contain oxygen the same law holds good. 

(3) If, however, the body contain water, the hydrogen of 
the water is first removed without substitution, and then the 
remaining hydrogen is substituted as in case No. 1. 

This last statement was necessary because alcohol, which 
was considered to be a hydrate of ethylene, CgH^H^O, is con- 
verted by chlorine into chloral, C2HCI3O. These rules are 
known as Dumas' theory of substitutions. 

15 Laurent, amongst the younger chemists, especially devoted 
himself to the advancement of this subject. He found that the 
replacement of hydrogen by its equivalent of chlorine does not 
always take place, particularly in the case of oxygenated bodies, 
and that for this reason Dumas' third rule is incorrect He 
also showed that in those cases in which substitution atom for 
atom takes place the physical and chemical properties of the 
substitution-product resemble those of the original body. 
Hence, he says, the chlorine takes up the position vacated by 
the hydrogen atom. In the new compound chlorine plays the 
part which hydrogen does in the original body.* 

Dumas did not support this view. He sta,tes that his theory 
i.s purely empirical, and when Berzelius urged, against him 
instead of against Laurent, that he entirely ignored the electro- 
chemical difference between hydrogen and chlorine, Dumas 
replies that Berzelius attributes to him a view, namely, that 
the chlorine takes the actual place of the hydrogen, diamet- 
rically opposed to that which he has always held. He adds, 
moreover, that he will not hold himself responsible for 
alterations which Laurent had made in his theory. 

Ill subsequent years the researches of Laurent, Regnault, 
and Malaguti, added a large number of substitution-products 
to those which were already known, and Dumas himself dis- 
covered trichloracetic acid, an instance in which, more than in 
any other, the substitution-product exhibits analogy with the 
original substance, go that at last Dumas not only adopted 
Laurent's views but expanded them considerably. 

x6 Before we proceed to the further consideration of the 
progress made in this direction it becomes necessary to mention 

* Dumas at that time employed the now QniFersally adopted atomic weight for 
ozTgi^u. ■ Ann, Chim, Phys, [2], Ivi. 140. 



16 HISTORICAL INTUODUCTIOy. 



a theory of chemical constitution brought forward by Laurent 
in 1836. This theory, termed the micleus theory, has indeed 
never been generally adopted, although Gmelin made use of 
it in his handbook with certain alterations, as a foundation 
for a classification of organic compounds. 

According to this theory each organic compound contains a 
group of atoms termed a nucleus or germ. Primary nuclei 
consist of carbon and hydrogen, and in these the hydrogen 
may be replaced by other elements or by groups of atoms. In 
this case derivative-^ or secondary-nuclei are produced, and 
these exhibit both in composition and in chemical properties a 
striking analogy to the primary nuclei. Other atoms may 
be attached to this nucleus, or they may quite surround it, and 
>vhen these are removed the primary nucleus makes its ap- 
pearance. Laurent ftirther assumed that organic compounds 
always contain an even number of atoms, and hence the 
formula) which he adopts are frequently double of those which 
are now employed. 

17 In the year 1839,^ Dumas developed the substitution 
theory to a theory of chemical types, the principles of which he 
thus enunciated : — 

(1) The elements of a compound body can, in many 
instances, be replaced, either by other elements in equiva- 
lents, or by compound bodies which are capable of playing 
the part of simple ones. 

(2) When such a substitution takes place in equivalent pro- 
portions, the body which is formed by such a substitution re- 
tains its clumical type, and the element which has entered into 
the compound plays the same 2^<^^^ ^s the element which has 
been withdrawn. 

In addition to the chemical types, in which Dumas included 
the following, 

CjH^Oj Acetic acid 

CjHjClOj, Chloracetic acid 

CjH^O Aldehyde 

C2HCI3O Chloral 



{ 
i 



{CHCI3 Chloroform 
CHBrj Bromofomi 
CHI3 Iodoform, 

' Conqtlcs Rcadus, viii. Ci»y. 



DUMAS' VIEWS. 17 



he adopted Regoault's suggestioa respecting tlie existence 
of molecular or mechanical types, according to which, two 
substances belong to the same type when substitution has 
taken place, provided that the number of elementary atoms 
remains constant. Under this he included compounds which con- 
tain the same number of atoms but possess different properties, 
such, for instance, as alcohol and acetic acid. 

Dumas pointed out, moreover, that the properties of a com- 
pound depend rather upon the arrangement of its parts than upon 
their special nature. He compared chemical compounds to a 
solar system of which the constituent parts are held together 
by their mutual attractions. The system remains the same if 
the atom of one element be replaced by that of another. 

As the best proof of the truth of his ideas, Dumas laid 
weight upon the fact that acetic acid, CJIfij^^ and trichloracetic 
acid, C^HCl^O^t possess the closest resemblance in chemical 
properties. 

Berzelius, who, as we have seen, opposed the theory of 
substitutions, pointed out the dissimilarity between the two 
I odies and insisted on the fact that their essential properties 
are distinctly different. He considered acetic acid as a hydrated 
oxide of a hydrocarbon-radical termed acetyl, CJI^, whereas 
trichloracetic acid is a copulated compound of oxalic acid and 
chloride of carbon : 

Acetic acid . . , C ^11.^,0^ + HO. 
Trichloracetic acid . • CJOI^ + C^O^ + HO. 

The constitution of other substitution-products wa:^ viewed by 
Berzelius in a similar light, although for this purpose he was 
obliged to double and sometimes to treble the simplest formula) 
of many compounds, and thus so to complicate the subject 
that his theory was not generally accepted. 

i8 Liebig opposed the views of Berzelius, which he said 
depended on a number of considerations which have no 
foundation in fact. He pointed out that even in inorganic 
chemistry the metal in permanganic acid can be replaced by 
chlorine without altering the form of the substance, although no 
two substances are more unlike than chlorine and manganese. 
Facts like these, he says, must simply be accepted. If manganese 
can be replaced by chlorine, why should a similar replacement 
of hydrogen appear incredible ? ^ 

In another place* Liebig remarked that Berzelius was the first 

* Ann, PJiamu xxxi. 119 (Lot note). • Ann, Pharm, xxxii. 72 (foot note). 
VOL. III. C 



i 



1« HISTORICAL INTRODUCTION. 

to adopt the view that organic acids, ethers, and so forth, are 
the oxides of compound radicals, and he admits that this 
view ilhimined many a dark chapter in organic chemistry. 
The analogy which Berzelius first pointed out between 
organic and inorganic compounds ought however, he con- 
tinues, not to be cairied on beyond a certain point, for if 
the principles of inorganic chemistry be consequently followed 
out in organic chemistry, the eflfect is rather that of com- 
plication than of simplification. 

At the same time Liebig did not hesitate to attack the French 
chemists,* who went too for for him, and when Dumas assumed 
that the carbon in organic substances could be replaced, he 
turned tipon him, and in a satirical vein, in a letter dated from 
Paris, and signed {anglice) S. Windier,^ relates how not only all 
the hydrogen and all the metal in acetate of manganese has 
been substituted atom by atom for chlorine, but how at last 
even the carbon has been in like manner replaced, and that 
the final product, although consisting of nothing but chlorine, 
possessed the chief characteristic properties of the original salt ! 

19 Facts bearing out the truth of the law of substitutions, 
so far at any rate as the replacement of hydrogen is con- 
cerned, rapidly increased ; but a still more important discovery 
was that of reverse substitutions, that is, the production of 
the original body from the substitution- product. 

In 1842 Melscns showed that by the action of potassium 
amalgam trichloracetic acid can bo converted into acetic 
acid. Such observations did not however convince Berzelius, 
who now looked upon acetic acid as an oxalic acid copulated 
with methyl, CJI^-^-C^O^-^- UO ; explaining in the same way 
the constitution of other compounds capable of undergoing sub- 
stitution, lie supposed that all these contained a group con- 
sisting of carbon and hydrogen, and termed by him the cojmla, 
in which the hydrogen is replaced by chlorine, etc. 

In 1845 Hofniann discovered the chlorinated anilines,* and, 
as Liebig in a note to this important investigation expressed 
his conviction in the truth of the newer views more strongly 
than before, Berzelius replied that all organic bases must be 
regarded as copulated ammonias. Aniline is the compound 
C,^//^ + y^^H, and chloraniline is C^^II^Cl + XH^ Both contain 
ammonia as a basic constituent. The composition of the 
copula is a matter of indifference. 

* Ann. Pharm. xxiv. 1. • Ann, Chtm, Pharm. xxxiii. 303, 

* Ann. CKtm. Phaim. liii. 8 ; Chem, Soc, Mem, ii. 200. 



ISOLATION OF THE RADICALS. 19 



In the assumption of the copula, the dispute \vith Laurent 
as to whether chlorine could replace hydrogen and fulfil its 
functions had been overlooked. That which was held to be 
absurd was at once accepted as a simple and clear expression 
of fact. Berzelius however continued in opposition. His 
formulae gradually became more and more complicated, and he 
was compelled to adopt more and more doubtful hypothescr 
Thus, for example, he represented dichlorformic ether, a com- 
pound obtained by Malaguti by acting with chlorine on ethyl 
formate, as being copulated of anhydrous formic acid, formyl 
chloride, anhydrous acetic acid, and acetyl chloride, giving it the 
formula 2C^IO^-\-C^Cl^-v2 C^ff^O^ + C^H^Cl^ ; whilst now, 
according to the new atomic weights, the formula is written 
C3H4CI0O,. We need not, therefore, be surprised to find that 
after Berzelius s death the supporters of his views experienced 
great diflSculty in rebuilding the radicals from the copula*. 

20 The railical theory had meanwhile received most valuable 
support from Bunsen's classical researches on the cacodyl com- 
pounds. He showed that these contain a common group of atoms, 
cacodyl (afterwards called arsendi methyl, (CH3)2As,) a body 
which exactly acts as a metal, and can exist in the free state.^ 
Soon afterwards Kolbe and Frankland succeeded in preparing 
from the compounds of the alcohol radicals the hydrocarbons 
which, according to their empirical formulae, must be con- 
si dererl as the free radicals. The isolation of the alcohol 
radicals as well as of cacodyl was naturally welcomed by the 
followers of the radical theory, inasmuch as it placed that 
which had hitherto only been a hypothesis in the I'ank of 
known facts. 

The question formerly much discussed respecting the pos^- 
sibiiity of the existence of a radical containing oxygen was 
again taken up. Berzelius had denied the possibility of the 
existence of such a body, and in 1843 he argued that this view 
is as incorrect as that which assumes sulphurous acid (sulphur 
dioxide) to be the radical of sulphuric acid, or manganese 
peroxide to be that of manganic acid. He adds : " an oxide 
cannot be a radical ; the very definition of the word radical is 
that it is a body which combined with oxygen forms an oxide." 
But as soon as the upholders of the radical theory adopted 
the theory of substitutions they were obliged to admit that 
the electro-negative element, chlorine, is capable of taking the 
place of electro-positive hydrogen without any great alteration 

» Ann, Ckem, Pkarm. xlii. 14 ; IWH. Mag, [3] xx. 313, 382. ^95. 

(• 2 



20 UISTOIUCAL IXTRODUCTION. 



occurring in the nature and properties of the compound ; and 
when this had been once admitted, the possibility that oxygen 
may also replace hydrogen could no longer be denied. 

21 The further development of the doctrine of substitutions 
and of the theory of types led to a clearer understanding 
of the terms equivalent, atom, and molecule. 

In this direction the development of the theory of polybasic 
acids had an especial value. It has been already remarked 
(Vol. ii. p. 35) that according to the dualistic view the neutral 
or normal salts of the oxyacids must be regarded as compounds 
of a basic oxide with an acid, or rather with an acid-forming 
oxide, whilst the acid salts must be considered to be com- 
pounds of a neutral salt Nvith a hydrated acid. Hence in 
those days the following formulae were in vogue : 

Hydrated sulphuric acid 110,80^ 
Neutral sulphate of potash KO.SO^ 
Acid sulphate of potash KO.SO^ + RO,SO^ 

According to these formula} the acid salt contains twice as much 
acid as the normal or neutral salt. 

Phosphoric acid and citric acid formed, however, exceptions 
to this rule, for these were considered as tribasic acids, and their 
formula.' as well as those of their salts are not divisible by 
three : 

I'iionpliotir A<'i<l. Arid SaltR. Kcntral Salts. 



Z' 



POt, VIO, PO^, 2HO, AafK P<\. UO. 2NaO. PO^. ZSaO, 

Citrir \iM\. 
C„//,0,j. :j//a C'„//bO,„ 2//0. KaO. C\^U^O^^, IIO. 2XaO. C^^fin- 3AaO. 

According to Berzelius the only reason for considering an acid 
to be iK)lybaHic is that its formula is not thus divisible.^ 

AfUT the publication of (iraham's classical investigations on 
the various modifications of phosphoric acid and its salts, Liebig- 
iti IS.'JS pn^iKKsetl his theory of polybasic acids founded upon a 
romphite investigJition of the salts of a number of organic 
acids. He showed that many organic acids resemble phos- 
phoric and citric acids inasmuch as one equivalent of these 
ciin take up from one to three equivalents of a base, Siicli 
acids he considered to be polybasic, even if their formulae were 
clivisibie. And he considered the capability of forming certain 
double wilts to l>e the special characteristic of this class of acids. 

» Krkulc, Lchrb, i. 80. « Ann. Phann. xxvi. 1,1. 



LAURENT AND GERHARDT. 21 

Tlio theory of polybasic acids was further developed by 
Laurent and Gerhardt, the latter pointing out that the property 
of forming two or more ethers was peculiar to these bodies. 
Whilst Laurent added that the same holds good for their 
amides. Both of these investigators, whose names will always 
be honourably associated in the history of the science, laboured 
incessantly to combat the views concerning the constitution of 
chemical compounds which they deemed incorrect, and to 
replace them by others which are more in harmony with 
ascertained facts. 

22 The interesting speculations of Lau ent and Gerhardt 
concerning the relative magnitudes of the atom and mole- 
cule went far to settle our views on these pjints, and the 
arguments which they made use of for this purpose hold good 
at the present day. 

Laurent founded his conclusions csixicially on chemical 
analogies, and upon the similarity observed in coiTesponding 
chemical reactions. Thus, for instance, he showed that a mole-' 
cule of chlorine must consist of two atoms, inasmuch as when 
it acts upon organic compounds either two, four, or six atoms, 
and never one, three, or five atoms take part in the reaction. 
He came to the same conclusion by comparing the action of 
chlorine with that of cyanogen chloride, benzoyl chloride, and 
similar compounds. All these substances exhibit strictly 
analogous metamorphoses, pointing to the conclusion that if 
the molecule of these chlorides consists of two parts, the same 
must also hold good in the case of chlorine itself. 

Gerhardt, on the other hand, starting from Avogadro's law, 
was led to a clear comprehension of the idea of an atom as 
being the smallest portion of an element which is contained 
in the molecule of any one of its compounds. 

The labours cf these two great investigators met, however, 
with but slight consideration during their lifetime. Laurent died 
early, and even Gerhardt only lived long enough to enjoy tho 
partial recognition of their views which soon afterwards became 
general. When Gerhardt first proposed the doubling of the 
atomic weights, or rather of the equivalent weights, then in 
use, for oxygen, sulphur, and carbon, Berzelius did not think 
tlie proposal worthy even of mention in his Jahresbericht. 

For the purpose of obtaining a sound experimental basis for 
their theoretical views Laurent and Gerhardt published many 
valuable experimental investigations. Little consideration 
was, however, paid to these results when they were correct. 



22 HISTORICAL INTRODUCTION. 



and when (as was sometimes the case) they were incoiTect, 
they were criticised with no sparing hand. Whilst recog- 
nising their great power of arranging facts from a general 
l)oint of view, we must admit that they frequently made 
assertions which rested more on a theoretical than an experi- 
mental basis, and hence their views were frequently criticised, 
especially by Liebig ^ as unscientific. Uninfluenced, however, 
by these attempts to discredit their work, and fully convinced 
of the truth of their ideas, they returned Liebig's sarcasm 
with interest. 

23 In looking back on these discussions we seem to enter a 
bygone age. Berzelius endeavoured to throw ridicule on the exist- 
ence of oxygenated radicals by saying that sulphur dioxide may 
as truly be considered as the radical of sulphuric acid. At the 
present day we actually adopt this view, considering this acid as 
a compound of sulphur dioxide (sulphuryl) with the semi- 
molecule of hydrogen [x?roxide (livdroxyl), for both of these groups 
of atoms fulfil the conditions which Liebig defined as charac- 
teristic of a compound radical. 

The employment of empirical, or unitary formulne as they 
were called, in opposition to dualistic, was a step in the right 
direction ; for every compound consisting of more than two 
elements is now considered as a chemical whole, and not as mado 
tip of several constituents. The unitary system also clearly point; 
out the general analogies of similar substances, and enables 
the facts to be brought into direct comparison, instead of viewing 
the constitution by the deceitful mirror of inherited hypotheses.- 

Certain groups of substances can thus be considered from 
the same i»oint of view, and their comjwsition indicated by 
general formula) such as CmHnOc, the adoption of which led 
to the taunt that Liiurent and Gerhardt were creating a sort 
of chemical algebra. Tlie use of such formulae, however, 
soon proved that the mutual relations of various compounds 
could not be thus so clearly exhibited as by the formulae of 
the radical theory. Accordingly Laurent and Gerhardt made use 
of the so-called synoptical formula;, in which the group of atoms 
remaining behind in a number of chemical metamorphoses was 
written in a separate iM)sition from the other constituents, or 
sometimes marked by a separate sign, the method of represen- 
tation at one time falli^ig into the radical and at another time 
into the nucleus theorv. 

24 TTnpi»rtant j)rogress was next made by the amalgama- 

* Ann. Chci, Vluii'tti. IviL 03, 3S*», ami hiii. 227. * Kckule, L^hrh, i. 84. 



THEORIES OF TYPES AND RADICALS. 23 



tion of the two theories of types and radicals. Dumas had 
already pointed out that hydrogen can not only be replaced 
by elements such as chlorine, but also by certain groups 
of atoms, stich as NOg; and that these may be desig- 
nated as compound radicals. Gerhardt revived this view in 
1839, but not exactly in the sense of the radical theory, ac- 
cording to which theory the radicals are closed groups of atoms 
and form the proximate constituents of compouuds. Here, 
however, it must be noticed that Liebig ^ had already pointed 
out that a radical is not to.be considered as an unalterable 
quantity, and that it was not necessary that the existence of 
the radical must precede the formation of an organic compound. 
Gerhardt did not assume that a substitution must occur when 
an element is replaced by a compound body, but rather that a 
combination of the two residues takes place to form a chemical 
unit, and not a copulated compound. The group of atoms which 
can be assumed to be a radical was termed " le rest " or " le 
restant." Then came his "thtSorie des residus" according to 
which such a residue possesses indeed the composition of a 
compound radical, but is not contained as such in the com- 
pound. Thus, for instance, the radical theory considers ethyl 
nitrate as nitrate of ethyl oxide, and the formula is written, with 
equivalent weights, CJIfi,NO^\ this ether is obtained by the 
action of nitric acid on alcohol : 

CJdfi -^ HNO3 = an^NOg 4- H,0. 

According to Gerhardt the reaction which here takes place is 
that the one compound gives up an atom of hydrogen, and the 
other the group or residue OH, and that these unite together 
to form water, whilst the two other residues form the chemical 
unit, ethyl nitrate. 

Gerliardt's theory of residues soon replaced the radicals of 
the old theory, and their assumption in the new theory of 
types brought about the union of the two theories. This was 
more especially effected by the discovery of the compound 
ammonias made by Wurtz* in 1849. Liebig* had foreseen 
the possible existence of such compounds, inasmuch as he pre- 
dicted that by uniting the alcohol radical with amidogen, ^Hj, 
compounds would be obtained possessing the characteristic 
properties of ammonias. Wurtz also assumed a corresponding 

^ Ann, Ph/inn, xiv. 166 ; xvm. 323, 

« ftympfes n^ndua, A out. 13, 1S49 ; Plill. ^fyg. [^] \x\v. 34. 

3 HandwdrUrb. i. 698. 



24 HISTORICAL IXTRODUCTION. 

constitution of these compounds, and he wrote the formula 
ethylamine (ethyliaque) C^HyNH^. Still, this iiiay be also 
considered, according to Berzelius's views, as a copulated am- 
monia, CaH^ + ^Hy Indeed Hofmann,* in his investigations 
on aniline, originally adopted this view, although he soon dis- 
covered facts which rendered it untenable. He showed that 
ethylamine is a substituted ammonia, (C^H^H^X, inasmuch as 
the second and third atom of hydrogen can also be replaced by 
the alcohol radical, and the compounds thus obtained still 
retain their characters as ammonias^ 

25 The discovery of the compound ammonias may certainly 
be regarded as the foundation of our present theory. From 
this time forwanl organic compounds have been arranged on 
the tif^s of certain simple inorganic bodies. Thus, for instance, 
it was assumed that in ammonia the hydrogen could be not 
only replaced atom for atom by metals (Laurent), but also by 
compound radicals. 

In 18.30 Williamson* showed, in an analogous way, that 
the alcohols and ethers may bo considered to be built up on the 
type of water. When in one molecule of the latter one atom of 
hydrogen is replaced by an alcohol radioed an alcohol is obtained. 
By the replacement of the second an ether is formed. This view 
he further exi^anded, inasmuch as he represented acetic acid as 
water in which an atom of hydrogen was replaced by the group 
CjHj^O, for which he proposed the name of oxygen-ethyl, or 
othyl, in order to distinguish it from tho word acetyl, already 
given by Berzelius to a radical containing no oxygen. At the 
same time he pointed out that by the replacement of the second 
atom of hydrogen by an oxygenated radical, compounds must be 
obtained which stand in the same relation to the fatty acids as 
ether does to alcohol These bodies, the anhydrous acids, or 
anhydrides, were 80c»n afterwards discovered by Gerhardt* 

For many yeai-s after this, chemists were accustomed to class 
organic compounds on the type of simple inorganic substances 
and thus arose Oerhardt's well-known tlieory of types, accord- 
ing to which the organic compounds of ascertained constitution 
may all be classed under four types : (1) that of hydrogen ; 
(2) that of hydrcxihloric acid ; (3) that of water, and (4) that of 
ammonia. Accordingly, we have the following : 

> Quart. Joum. Chem, Soc. i, 23.1, ii. 334. 

- Hn'fixh Assw'iation Ilrporh, IbjO, part ii. p. G.'i ; Chcm, Soc, Joum. (1852), 
ir, 22l«. 
" (Juarl. Joum. Chem. Hoc. v. 127 ; Ann. Chim. Phys. fa], xzxvii. 285. 



GERHARDTS TYPES. 



25 



o 

Q 

a 



o 

a 






d 



Q 



WW 

CI 91 



WWW K^WW wVW tCffiV 



d 

• 1-4 

a 



Eh 



CM 
W 

CI 




• ■-4 

a 

o 
o 



O 
OO 



A* 

H 

P 
PS 

o 



I 




<J 

•c 

o 

3 

s 



WW 



o 

o 











rd 



w 



CI 






<D 



WW 

CI CI 






o 



O 



o 

'C 
o 

3 

d 

0) 

bo 

s 

O 



d 

& 

w- 






rd 






o 



26 HISTORICAL INTRODUCTION. 



The organic bromides and iodides are of course classed iu the 
second division, whilst many sulphur compounds are found in 
the third, and bodies containing phosphorus and arsenic are 
arranged in the fourth class. This system was further de- 
veloped by the classification of many inorganic bodies, such as 
the oxyacids which are ranged under the type of water. 

26 A further advance in the theory of types was made by its 
application to the classification of poly basic acids, such as suU 
phuric acid. In the memoir already referred to, Williamson had 
placed this acid under the double water type, inasmuch, as he 
assumed, that it might be considered as two molecules of water 
joined together by the replacement of two atoms of hydrogen by 
a group of atoms, whilst a monobasic acid belongs to the typo 
of one molecule of water. In a similar way the other dibasic 
acids and their salts may be arranged : 



Type. 


Acetic Aci<l. 


Nitric Acid. 


S}o 


CAo^o 


KG, ) Q 


Type 


Sulphuric Acid. 


Succinic Acid. 




H j. 

11 [^ 


Ho 



Williamson^ then showed in 1854 that chloroform may be 
considered as the trichloride of the radical CH. When it is 
heated with sodium ethylate, CoH^.ONa, it yields tribasic formic 
ether, CH(OCoH5)3, and this belongs to the type of three mole- 
cules of water exactly as chloroform is classed under the type of 
three molecules of hydrochloric acid : 

Tyjie. Chloroform, Tvi>c. Tribasic formic ether. 

CII 



3H01 CH. CI, 3Hp 



(C 



i^u}"- 



This view of the constitution of chemical compounds was 
further developed by Odling,^ and applied by him to a large 
number of organic as well as inorganic compounds. They were 
then adopted by Gerhardt in 185G, and published in his Treatise 
on Organic Chemistry.* 

27 As the possibility of the replacement of several hydrogen 
atoms by a radical was first observed in the case of polybasic 

* Pi'oc, Iloif. S'X, vii. l.^."). ' Qimrf. Jovi-n, Chun, Ak*. vii, 1. 

* Ti-niii f'/thrt, Ot'tj. iv. 6^1, &c. 



WILLIAMSON'S VIEWS. 27 



acids, the radicals themselves were termed in the first cacs 
polybasic, and this expression was afterwards changed to poly- 
atomic radicals. This latter term is, however, not wholly free 
from objection, and at present the proposal of Erlenmeyer to 
employ the word polyvalent is generally adopted.^ 

The theory of polyvalent radicals soon received valuable sup- 
port from Berthelot's investigation of glycerin and its deriva- 
tives, the constitution of these compounds being first clearly 
pointed out by Wurtz. Indeed this chemist must be considered 
to be one of the originators of the new theory of types, not 
only on account of the above-mentioned views, but especially 
by his valuable discoveries of the glycols or divalent alcohols. 

According to this theory, as we have seen, the radicals are not 
to be considered as closed groups of atoms, or even as bodies 
capable of isolation, but rather as the residues of molecules 
which remain unaltered throughout a certain number of reac- 
tions. Gerhardt first pointed out that most chemical decom- 
positions may be regarded as double substitutions, and he added 
that if the substances which exchange their positions in such 
a reaction are compound bodies instead of being elementary 
ones, they are then termed radicals. 

28 These typical formulae were not intended to indicate the 
arrangement of the atoms ; they were in no sense constitutional 
formulae, but were formulae of decomposition used by common 
consent, and expressing a certain immber of reactions. One 
of these compounds may, therefore, be represented on various 
types. 

Thus, for instance, methyl ether, C^H^O, was usually supposed 
to belong to the water type, but it may also belong to the fourth 
type of marsh gas, which Kekule added to Gerhard t's three 
original tj'pes. Under this latter assumption it would consist 
of two molecules of marsh gas held together by one atom of 
dyad oxygen : 



Type. 








> Ix)thar Meyer, Moil Thcor. dcr C/icmtc, 3rd Ed. p. 140. 



28 HISTOUICAL INTRODUCTION. 



By replacing the hydrogen in ammonia by methyl, methyl- 
amine, CH^N, is produced ; this may be regarded as a substi- 
tuted ammonia, but it may also be looked upon as marsh gas in 
which hydrogen has been replaced by the monad group, NH, ; 
and lastly, it may be represented as having been formed by the 
union of two monad residues, and hence may be classed in the 
type of hydrogen ; thus : 

aUl C^'S INH. 



1h n« 



NHj 



defiant gas combines with bromine to form ethylene di- 
broniide, CgH^Bro. In this the bromine can be replaced by 
hydroxyl when ethylene alcohol (ethyl glycol) is formed. These 
two compounds may be typically regarded as follows : 

Ethylene dibromidc ^^^*| C2H4}bJ 

Ethylene alcohol ^^* | O., C,H, | ^^ 

By the action of hydrochloric acid on the latter body the 
liydroxyl is first replaced by chlorine when ethylene chlor- 
hydrate is formed, and this, on oxidation, yields monochloracetic 
acid. 

29 Hence ethylene chlorhydrate may be considered as a 
chlorinated ethyl alcohol. It may, therefore, be regarded on the 
mixed types of water and hydrochloric acid, the two molecules 
being united by tlie replacement of one atom of hydrogen in 
each by the dyad radical CgH^ (formula No. 1). Or we may 
consider it to bo a compound of ethylene with chlorine and 
liydroxyl ; or again it may be represented on the type of water 
(formula No. 2), or on the mixed tjpc of hydrochloric acid and 
water (formula No. 3). 

(1.) (2.) (3.) 



HJO 



(Oft ' Hf 



When clilorapctic acid, also obtaiuetl bv the action of chlorine 
on acetic acid, is treated with ammonia, amidacetic acid, 



inxED -nTEa » 

CjHjNHjO,, is formed. This, like the componnds from which 
it is produced, ia moDobasic. It presents, however, certain 

analogies ivith the compound ammonias just as chloracetic acid 
ciliibitB properties analogous to those of ethyl chloride, and 
licnce the formulae of these compounds may be written in 
different ways : 

{1) (21 (S) (1) (5) 

CI) 

acij '-'"'** (OH lip cii ^'"'^in 



Ami.lflMtic f, H (, ( NH, C,H,(SH.)0 

„,.;.( <'5"i'^i mi II 






The first of these formulae point out that these compounds 
contain the dyad radical CjHjO^. The second and third 
formulae show that we have to do with substitution-products 
of acetic acid. These may be regarded as compounds of a 
monad radical, inasmuch as amidacetic acid is formed from 
chloracetic acid, one atom of chlorine btiiip; nplaced by tho 
monad-amido group. The fourth series of foniiiiliB constructed 
on the mixed type of water and hydrochloric acid, indicate the 
water-ammonia type; whiUt in the fifth case amidacetic acid 
J3 represented as a compound nmmonia. Which of those for- 
mulae is to be preferred depends upon which of the relations of 
the compounds it is especially desiitd to lay weight. It in usual 
to choose those by which the mere important reactions are most 
clearly represented, 

30 In 1838 Gerhardt pointed out that by the action of 
sulphuric acid on various compounds bodies are formed in 
which the characteristic properties of the constituents are not 
reproduced. In order to distinguish combinations of this kind 
from ordinary compounds, he termed them copulated compounds. 
The original views thus propounded by him were afterwards 
considerably enlarged and modified by Berzelius, who, although 
he at first ridiculed Oerhardt's idea of copulated compounds, 
afterwards, as we have seen, adopted the name. With the 
notion of these copulated compounds that of copulated radicals 
is intimately connected. 

According to this view many radicals are supposed to be 
made up of several simpler radicals. Thus, lor instance, many 



80 HISTORICAL INTRODUCTION 



monobasic acids which belong to the type of water may bo 
written, first of all, according to the water t}'pe : 

Type. Formic Acid. Acetic Aciii Propionic Acid. 

g}0 C«g|0 C,H,OJo CH^Oj^j 

But these compounds are frequently found to decompose in 
such a way that the group carbonyl, CO, is liberated as COj, 
together, in the case of formic acid, with liydrogen, and, in the 
case of the others, with an alcohol radical. The radicals of these 
acids may, therefore, be looked upon as containing carbonyl, and 
either hydrogen or an alcohol radical. This is represented in 
the following formulae : 

Fonnic Acid. Acetic Acid. Propionic Acid. 

H.COI0 CH,C01|.o C,H,COjo 

The employment of the intermediate types led to the re- 
presentation of these acids together with other compounds, as 
containing copulated radicals thus : 




Formic Acid. Acetic Acid. Propionic Acid. 

HI CH3 ) C,Hj ) 

CO f CO j CO [ 

h}o h[o h}<^ 



The followers of Berzelius, especially Frankland and Kolbe,* 
considered these acids as conjugate compounds, but as these 
chemists did nut recognise any oxygenated radicals, they looked 
upon acetic acid as the hydrate of a compound of oxygen 
with acetyl containing methyl and carbon, and they expressed 
the constitution of acetic acid by the formula HO, (C^^C^^O^ 
without admitting the new atomic weights.^ 

The development of the theory of types played an important 
part in the history of the science. Instead of supporting the 
view of the unalterability of the radicals, it led to the notion 
that the residue consists of groups of atoms which, in a certain 
series of metamorphoses, remain unaltered, whilst under other 
circumstances they may undergo change. It also threw a new 

' Chem. Soc. Mem. iii. 890. 

* The reader will lind a fuU account of the new theory of typos as well as of 
copuhited radicalri in Kckule'a Lehrhuch der organiachtn Chcmie, and in his 
memoir *'on the so-called co[>uIated compoauds and the theory of polyatoinio 
radicals." — Ann, Chem, PJiarm, civ. 129. 



DEFINITIOXS OP ORGANIC CHEMISTRY. 81 



light upon facts in other directions, explaining certain analogies 
and diflferences, and thus rendering possible a general view 
respecting the behaviour of the atoms in compounds.^ 

31 Before however we can enter into this question we must 
refer to another point and once more look back to the time 
when Williamson applied the theory of types to inorganic com- 
pounds, and showed that the existence of compound radicals 
must be assumed in these just as much as in organic substances; 

Even before this tin.e many salts, such as those of ammonium 
and those of uranyl, had been considered to contain compound 
radicals, but the number had then so largely increased that 
organic chemistry could not be correctly defined to be the 
chemistry of compound radicals. 

All the organic compounds formed in nature contain carbon 
and hydrogen. Most contain oxygen as well, and many nitrogen. 
According to the older views it was, however, supposed that 
the hydrogen was, in many compounds, as, for instance, in oxalic 
acid, combined with oxygen to form water. Thus carbon was 
in some cases found to be the only remaining constituent, and 
this fact was pointed out by Gerhardt, in 184G. 

Hence, organic chemistry was defined as the chemistry of 
the carbon compounds, as well as that of the radicals con- 
taining carbon. According to this definition, however, many 
compounds of this element must be considered to belong to 
organic chemistry although they are not formed from the bodies 
of vegetables or animals and occur in the mineral kingdom. 
Such bodies are carbon dioxide and marsh gas. This difii- 
cuity of classification has been avoided in various ways. Thus, 
Gmelin * in his Handbook says : " Carbon is the only element 
which is essential to organic compounds ; every one of the 
other elements may be absent from particular compounds, but 
no compound which in all its relations deserves the name of 
organic is destitute of carbon. ... If we were to regard as 
organic, those carbon compounds which have hitherto been 
classed amongst inorganic substances, namely carbonic oxide, 
carbonic acid, sulphide of carbon, phosgene, cast-iron, &c., we 
might define organic compounds simply as the compounds of 
carion. But organic compounds are still further distinguished 
by containing more than one atom of carbon. . . . Htnce 
the term organic cowfounds includes all primary compounds 

* Lothar Meyer, 3fo<L Theor, dcr Chemie, 8rd Ed. p. 150. 

* Uandbool; vii. 4 aud 5. 



32 HISTORICAL INTRODrCTIOX. 



containing mere than one atom of carbon. By primarr com- 
pounds we mean such as are not, like bi-carbonate of potash, 
made up of other compounds." 

In order to understand this definition it must be remem- 
bered that in those davs, the atomic weight of carbon was 
supposed to be only half as great as that which is at present 
assigned to it, and this remark applies also to oxygen, sulphur, 
and seyeral other elements. Thus the followini;^ formulae were 
then employetl : carbonic oxide, CO ; carbonic acid, CO^ ; 
phosgene gas, COCl ; and carbon disulphide, CS^; whilst to 
the organic compounds of most simple constitution, the follow- 
ing formulae were assigned: methyl alcohol, CJIJ[)^\ fonnic 
acid, CM/J^ ; hydrocyanic acid, CJIX\ cidoroform, CJSCl^ 

As soon, however, as it appeared that the atomic weights of 
the above elements must be doubled, and that the molecule 
of carbon dioxide or carbon disulphide contained exactly the 
same number of atoms of carbon as one molecule of methyl 
alcohol or of formic acid, either Gmelin's definition could no 
longer hold goo^l, or the latter compounds must be considered 
to belong to inorganic chemistry, or, in the third place, the oxides 
and the sulphide of carbon must be considered to be oiganic 
compounds. 

On this question Kekul^ remarks : " We must come to 
the conclusion tliat the chemical compounds of the vegetable 
and animal kingdom contain the same elements as those of 
inanimate nature. We know that in both cases the same laws 
of combination liold good, and hence that no difterences exist 
between organic and inorganic compounds, either in their com- 
ponent materials, in the forces which hold these materials 
together, or in the number and the mode of grouping of their 
atoms. Wo notice continuous series of chemical compounds 
whose single members, especially when only those which lie 
close together, arc compared, exhibit strong analogy, and be- 
tween which no natural division is perceptible. If, however, 
for tho sake of perspicuity a lino of demarcation is to be 
drawn, we must remember that this boundary is an empirical 
rather than a natural one, and may be traced at any point 
which SiH'ms most desirable. If we wish to express by 
organic chemistry that which is usually considered under 
tho name, we shall do best to include all carbon com- 
pounds. Wo, therefore, define organic chemistry as the che- 
mistry of the carbon compounds, and we do not set up any 



DEFINITIONS OF ORGANIC CHEMISTRY. 33 

opposition between inorganic and organic bodies. That to 
which the old name of organic chemistry has been given, and 
which we express by the more distinctive term of the chemistry 
of the carbon compounds, is merely a special portion of pure 
chemistry, considered apart from the other portion only because 
the large number and the peculiar importance of the carbon 
compounds renders their special consideration necessary."^ 

Other chemists have expressed themselves in a similar way. 
Thus Butlerow states that a division of the kind is needed both 
in the interest of the student as well as in that of the scientific 
investigator. The carbon compounds exhibit certain peculiari- 
ties in consequence of which their investigation demands special 
methods, which are not necessary in the case of the other ele- 
ments.* Another reason for treating the carbon compounds 
separately is the enormous mass of material which presents 
itself for investigation, so that although such a division is an 
artificial one, it is one which is extremely useful.* 

32 The distinction between these classes of carbon compounds 
is, however, one which up to the present time has never been 
carried out in every detail. Thus, no chemist has ever thought 
it advisable to omit such substances as the oxides and the sul- 
phide of carbon from the inorganic portion of his work, or 
to class substances like carbonate of lime, or spathic iron-ore, 
or even cast-iron, under the head of organic compounds. Hence 
we find a description of the oxides of carbon, of carbon disul- 
phide, and of their various derivatives, generally placed in 
the divisions both of inorganic and of organic chemistry. In 
the same way the cyanogen compounds are frequently de- 
scribed both in inorganic and in organic treatises. The ex- 
planation being, that these bodies contain only one atom of 
carbon, and that they are in many respects analogous to 
the compounds of the elementary bodies. Wood-spirit and 
formic acid, on the other hand, which also only contain one 
atom of carbon in the molecule, are never considered as inor- 
ganic compounds, for they are closely connected with alcohol, 
acetic acid, and other bodies containing a larger number of 
carbon atoms, whose peculiar properties orginally led to the 
distinction between the two great branches of pure chemistry. 

33 This peculiarity depends upon the fact that they are 

* Lehrbueh d, org. Chemie, i. 11. 

* Butlerow, Lekrb, d, org, CTiem, 5. 

' Erlenmeyer, Lehrb. d, org. Chem, p, 5, 

VOL. ni. D 



34 HISTORICAL INTRODUCTION. 



carbon compounds, for carbon possesses properties by which 
it is distinguished from all other elements. In the first place 
we have to remember that hydrogen is found in all organic 
bodies in addition to carbon; in most others oxygen occurs; 
and in many nitrogen is also contained. Others again consist 
of carbon, hydrogen, and nitrogen only. 

The number of these bodies is enormously large. Carbon yields 
more compounds than all the other elements taken together. 
Moreover, the number of atoms contained in the molecule may be 
very considerable. Thus, for instance, oil of turpentine consists 
of carbon and hydrogen, and contains 26 atoms ; cane-sugar, 
which in addition contains oxygen, contains 45 ; and stearin, 
also an oxygenated body, contains 173 atoms. 

Kekul^,^ who first pointed out that carbon is a tetrad element, 
showed at the same time that the existence of so large a number 
of carbon compounds may be explained by the fact that the 
atoms of this element have the power of combining one with 
another. A similar view was also put forward shortly afterwards 
by A. S. Couper.^ 

The atoms of other polyvalent elements, such as oxygen, sul- 
phur, &c., are indeed found to combine with one another, but 
the number which can be thus connected together is in their 
case a very limited one. With carbon, however, such a limit 
to the power of combination has not yet been reached. A large 
number of its atoms are capable of uniting to form a chain 
which in many reactions behaves as if it were a chemical unit. 

Still more clearly however is carbon distinguished from all 
the other elements by the fact that in such a chain of atoms 
all the free combining units can he saturated hy hydrogen. Hence 
the existence of a large number of hydrocarbons becomes pos- 
sible. These are all volatile, whilst amongst the hydrogen 
compounds of the other elements only those of the chlorine, 
oxygen, nitrogen, boron, and silicon groups are volatile, and in 
the case of each of these (with the exception of phosphorus) 
only one hydride is known. 

The hydrocarbons are however not only the simplest, but at 
the same time, on theoretical grounds, the most important, 
compounds of this element, especially because all the other 
compounds may be derived from these by the replacement 
of hydrogen by other elements. In the organic compounds 

* Ann. Ch(m. Pharm, civ. 129 ; cvi. 129; Lehrhuch, i. 161. 
« i'AjY. Maff. [4], xvi. 104. 



DEFINITION OF ORGANIC CHEMISTRY ADOPTED. 36 



occurring in nature we usually find a portion of the hydrogen 
replaced by oxygen or by nitrogen, or by both of these elements. 
Some few are found to contain sulphur. All the elements 
may be made to combine with carbon compounds, but it is only 
in a few instances that all the hydrogen in the hydrocarbon 
can be replaced by another element. This explains the feet 
which has already been mentioned, that by far the larger pro- 
portion of carbon compounds contain hydrogen, or a residue of 
the hydrocarbon from which they all are derived. 

34 Hence we may define that portion of our science which 
is usually denoted as organic chemistry as being the chemistry 
of tJie hydrocarbons and their derivatives. The characteristic 
nature of this definition is seen from the fact that, when the 
general chemical constitution of a carbon compound has been 
nghtly ascertained, it can be converted into the corresponding 
hydrocarbon, or, inversely, it may be prepared from this latter 
compound. 

In employing this definition, we do not draw any distinctive 
line between organic and inorganic chemistry, for the simpler 
carbon compounds which have already been described in the 
inorganic portion of this work, such as carbon dioxide, carbon 
oxychloride, sulphide of carbon, hydrocyanic acid, &c., all of 
which contain one atom of carbon, may be looked upon as direct 
derivatives of a hydrocarbon, namely, marsh gas, CH^. From 
this they can all be prepared, and into this they can all be 
converted. When this gas is burnt in the air, water and 
carbon dioxide are formed, the monad hydrogen being replaced 
by dyad oxygen. Marsh gas can also be directly converted 
into carbon disulphide, and when the vapour of the latter 
body is passed together with sulphuretted hydrogen over red- 
hot metallic copper, the sulphur is substituted by hydrogen, 
and the hydrocarbon, marsh gas, is formed. If this latter 
compound be treated with chlorine, the first product which is 
obtained is methyl chloride, CH3CI, and when this is heated 
with caustic potash, wood-spirit, or methyl alcohol, CH^O, is 
obtained : 

CH3CI + KOH = CH3.OH + KCl. 

When this alcohol is oxidised, formic acid is produced, two 
atoms of hydrogen being replaced by one atom of oxygen. By 
the further action of chlorine on methyl chloride the successive 

1) 2 



36 HISTORICAL INTRODUCTION. 



replacement of all the hydrogen by chlorine takes place, the 
last product but one being chloroform, CHCI3 ; and if this sub- 
stance be heated with ammonia, hydrocyanic acid is obtained, 
three atoms of chlorine being replaced by one atom of triad 
nitrogen : 

CHCI3 + 4 NH3 = CHN + 3 NH^. 

As all the cyanides can be derived from hydrocyanic acid, 
they may be all considered as derivatives of marsh gas. The 
carbonates may be similarly considered to be derived from 
marsh gas, for wc must assume in the aqueous solution of 
carbon dioxide the existence of carbonic acid, C0(0H)2, that is 
to say, marsh gas, in which one-half of the hydrogen has been 
replaced by oxygen, and the other two by hydroxyl. Indeed 
the various varieties of cast-iron may even be regarded as deri- 
vatives of hydrocarbons, inasmuch as when cast-iron is dissolved 
in hydrochloric or sulphuric acid the carbon which is combined 
with the iron gives rise to hydrocarbons in which the hydrogen 
may be said to have replaced iron. 

35 Only one single carbon compound is known for which the 
corresponding hydrocarbon does not exist. This is the simplest 
of all carbon compounds, viz. carbon monoxide. All endeavours 
to isolate the hydrocarbon CHg have as yet proved abortive, 
and there are good reasons for behoving that the existence 
of such a body in the jfree state is not possible. No other 
hydrocarbon except marsh gas is known which contains only 
one atom of carbon. On the other hand, we are acquainted 
with three which contain two atoms of carbon : 

Ethane, CgH^. Ethylene, CgH^. Ethine, CgHy 

In order to explain the constitution of these substances it 
is assumed that in ethane the two carbon atoms are connected 
together singly ; in ethylene by double linking ; whilst in ethine 
or acetylene the three combining units of the two carbon atoms 
are supposed to be linked together. 

A Large number of carbon atoms may be combined together 
in a similar way, and thus the above hydrocarbons form the 
first members of groups of which each is distinguished from 
the preceding by an increment of CH^. The composition of 
these may be expressed by the following general formuloe : 



nYDROCARBONS AND THEIR DERIVATIVES. 



37 



Series. 


CnHsn -f 2. 


CnUsn* 




Jfethane 
Ethane 


CH4 






Ethylene 


C,H, 


Propane 


^3^8 


Propylene 


CsHg 


Butane 


C4H10 


Butylene 


Gfis 


Pentane 


C5H12 


Pentylene 


^6^10 


Hexane 


CeHu 


Hexylene 


CcHia 


&c. 




&c. 





C„Hsn- 



Sn-2> 



Ethine 
Propine 
Butine 
Pentine 
Hexine 
&c. 



CgHg 
CgHg 



Besides these, other groups, such as CnH2n-4 and CnH^-a 
&c., are known. The first members of these naturally contain 
more than two atoms of carbon. 

36 Other carbon compounds can be derived from these various 
series. Thus, for instance, just as by the action of chlorine on 
marsh gas methyl chloride is obtained, so the other members of 
the marsh gas series yield chlorides of monad radicals having 
the general formula CnH2n+iCl in which chlorine can be easily 
replaced by hydroxyl, and thus a series of hydroxides are ob- 
tained to which the names of alcohols have been given, and 
to which the general formula CnH2n+20 is applicable. 

When methyl chloride is heated with ammonia, a strong base 
is obtained, which has received the name of methylamino : 

CH3CI + NH3 = CH3NH2 + HCl. 

And by a similar reaction with the other chlorides a series of 
such bases or amines is obtained having the general formula 

Moreover, as methyl alcohol gives rise to formic acid by 
oxidation, so these other alcohols yield a scries of acids 
Laving the general formula CnH2u02, obtained by the replace, 
ment of two atoms of hydrogen in the alcohol by one of oxygen. 
Many of these acids are found in fats and oils, and hence they 
are termed the fatty acid series, or the adipic series of acids. 
Thus we obtain the following series from the marsh gas hydro- 
carbons : 



Chloride. 
c^firide I <^»"»^^ 

Pentvl } r- TT n 
eUonde j ^•""^* 



AlcohoL 



"ilcXi CH.0 

Ethyl i p u n 
alcohol ^»"«^ 

Propyl I p ri n 
alcohol i ^»*^8" 

iSihol I ^*"*oO 
Tkohol 1 ^»Hi,0^ 



Hcxyl 
alcohol 



C,H„0 



Amine. 
Methylamine C HjN 

Ethylamine CSH7N 

Propylamine C3H9N 

Butylamine C^HuN 

Pentylamine C^H^sN 



Fatty Acid. 
Formic acid C H,Cj 

Acetic acid C3H4O2 

Propionic acid C^Ufi^ 

Butyric acid C4HgOj 

Pentylic acid CjHioO, 



Hexylamine QHuN j Hcxylic acid C^Uifi^ 



38 HISTORICAL INTRODUCTION. 



In addition to these, a large number of other derivatives of the 
above hydrocarbons is also known, and these again yield other 
groups which can all be arranged in corresponding series. All 
the hydrocarbons contain an even number of atoms of* hydrogen ; 
this being owing to the tetrad nature of carbon. For the 
same reason it also follows thcU the sicvi of the atoms of nionad 
and triad elements which arc contained in a molecule of a carbon 
compound is always an even nu?nber, 

37 In 1842 Schiel ^ remarked that the alcohol radicals form 
a very simple and regularly graduated series of bodies, of which 
the properties as well as the composition exhibit corresponding 
regular gradations. He gave the following description, the old 
equivalents being used : 

Cg-H!, = R 

EU . . ." Methyl. 

Bjr Ethyl. 

R^H Glyceryl 

R^H ? 

R^H Amyl. 

R^qH , . Cetyl. 

R^^H Cerotyl. 

He also predicted the existence of other series. Shortly 
afterwards, Dumas^ showed that the fatty acids form a similar 
series, and that in these, as Schiel had pointed out in the case 
of the alcohols, the boiling-point regularly rises with the 
increment C^H^, 

In his Precis de Chimie organique, published in 1844, Ger- 
hardt collected together a large number of such groups, and was 
the first to give to these the name of homologous scries, whilst he 
classed the bodies obtained from one another by definite 
chemical metamorphoses, such, for instance, as ethyl chloride, 
ethyl alcohol, acetic acid, &c., as Jictcrolojous scHes. 

This classification into homologous and heterologous series 
Gerhardt compares to the arrangement of a pack of cards. 
The cards of each suit being placed in regular order 
in a vertical line, those of equal value in the different 
suits will be found in a horizontal row. These latter corre- 
spond to the homologous series, whilst the first represent 

» Ann, Chim. Pharm. xliii. 107. ' Ibid. xlv. 330. 



HOMOLOGOUS SERIES. 39 



the heterologous series. If one card be wanting, its place is 
nevertheless indicated, and, although absent, we know its exact 
character. In the same way with organic compounds. When 
the series is not complete, the composition of the missing 
substance can not only be predicted, but even its more im- 
portant properties indicated. Of its possible existence there 
can be no doubt, and if it is desired to complete the series, this 
can be done by employing suitable reactions. 

If we compare the various members of one such series of homo- 
logous bodies together, thus, for example, those of the marsh gas 
hydrocarbons, CnH2n+2, we find, in the first place, that they difi^er 
from one another in physical properties. The lowest members are 
gases at the ordinary temperature ; the members next following 
are liquids whose boiling-points increase with their molecular 
>veights, whilst the highest members are solid bodies, which are 
volatilised only at a high temperature. The same holds good 
with the other series. Their lowest members are either gases 
or volatile liquids; the highest, on the other hand, are solid 
bodies either only volatilised with difficulty or undergoing 
decomposition when heated. 

We next observe that the chemical character of each group 
depends essentially upon the mode in which the carbon 
atoms are connected with one another, as well as with the 
rest of the elements contained in the molecule. For this reason 
the corresponding members of each homologous series closely 
resemble one another in their chemical relationships. One 
result of this is that whilst the comparatively limited number of 
compounds which the other elements form renders it possible that 
the nature and composition of the compound can be determined 
by a few reactions, this, on the other hand, is only exception- 
ally possible in the case of the carbon compounds. In most 
instances it is necessary for this purpose not only to prepare the 
body in the pure state, but also to determine its physical and 
chemical characters, and then to pass on to the determination of 
its quantitative composition. Not only do newly discovered bodies 
require this complete treatment, but frequently this is the only 
mode by which substances which have long been known can be 
satis&ctorily recognised. Hence we shall now pass on to describe 
the methods which have been employed, and are still in use, for 
the vMimate analysis of the carbon compounds. 



ULTIMATE OBGANIC ANALYSIS. 



ULTIMATE OEGANIC ANALYSIS. 

DETERMINATION OF CARBON AND HYDROGEN. 

38 The first successful analysis of an organic compound 
was carried out by Lavoisier, and tlie principle upon which he 
founded his method fur the determiuation of carbon and hydro- 
gen is the same aa that which is employed for a like piirpose at 
the present day. The body to be analysed is completely burnt. 




the titiantity of carbon dioxide and watur thus produced being 
uccumtoly <)otcni)iiied. 

Lavoisier'g Afrthmi. Tho apparatus used by Lavoisier ' for this 
purpose is shown iu Fig. 1. Tho glass btli-jar A, carefully 

> ilrm. Am^. i;^l (piibliJwd in 1781), ati.I ibid. V.fii (i>ul>tuhed in 1787). 



LAVOISIER^S METHOD OF ANALYSIS. 41 



calibrated and standing over mercury, contains common air. 
Into this is brought a weighed lamp fed with the alcohol or oil 
to be analysed ; on the wick a small piece of phosphorus is 
placed, and this can be inflamed by contact with a warm bent 
wire. The bell- jar s contains a measured volume of oxygen 
standing over water. By lowering this, the oxygen can be 
passed over into the vessel A for the purpose of completing 
the combustioiL As soon as this is eflfected, the carbon dioxide 
formed by the combustion is absorbed by caustic potash, and 
from the volume of this gas, together with that of the air 
which remains behind after the combustion, and from the volume 
of unbumt oxygen, Lavoisier calculated the composition of the 
alcohol or oil which had undergone combustion in the lamp. 
In this way, however, he arrived at altogether erroneous 
results, inasmuch as he was not acquainted with the exact com- 
position of either carbon dioxide or water, and the numbers 
which he used for the specific gravities of the various gases 
employed were by no means accurate. Nevertheless, if his 
results be recalculated with the adoption of correct constants, it 
appears that his analyses were at least as accurate as those of 
many chemists who in the following years occupied themselves 
with the subject. 

LavoLsier even then observed that the indirect determina- 
tion of water by the subtraction of the weight of carbon dioxide 
from the sum of the weights of the burnt substances and the 
oxygen employed for the combustion might with advantage be 
replaced by a direct determination of this substance. Later 
on, indeed, he described an apparatus for the burning of large 
quantities of oil, in which both the water and carbon dioxide 
formed are weighed. This method has a special interest, as 
the arrangement of the apparatus closely resembles that in use 
at the present day.^ The apparatus used is shown in Fig. 2. 
The combustion takes place in A, and the oil for the lamp is 
introduced at a. The gas-holder (p) is filled with oxygen, and 
this gas passes through b, and is dried in the tube p. The 
products of combustion pass through c into the absorption- 
apparatus. The greater portion of the water collects in the 
bottle (/), and that which escapes is deposited in the spiral tube 
(A), wlnlst the last traces are taken up in the tube Jc, which 
contains a " deliquescent salt." The gases then pass through a 
system of bottles (ff), of which only two are represented in the 

^ Layoiaicr's Elements (Kerr's translation), 503. 



42 ULTIMATE ORGAXIC ANALYSIS 

figure, although Lavoisier employed eight or nine. Theae, with 
the eiceptioD of the last, contaiD caustic potash, lime-water 
being placed in the last one in order that the complete ab- 
sorption oC the carbon dioxide may be recognised by the 




nuii-turbidity of the lime-water. The first experiments made 
with this apparatus did not yield very satisfactory results, and 
his endeavours to improve the method were cut short by his 
untimely execution in May, 1791. 



44 ULTIMATE OBGANIC ANALYSIS. 

cumbustioQ was efrecte<l in an apparatus the constructioD of 
which is shown in Fig. 3. The closed lower end of the hard glass 
tube AA, 2 dciQ. in length and S mm. in diameter, is placed 
upon a charcoal fire, or strongly heated by an alcohol lamp 
(u). The upper end of this conibustion-tube is closed with a 
stopcock, which, however, is uot bored through, but has a cavity 
bored into the stopper. A pill is placed in this cavity, and the 
stopcock turned, when the pill falls into the ted-hot tube. By 
repeatingthis operation, all the air contained in the combustion- 
tube is driven out by the side tube. A weighed quantity of 
the pills is then gradually added, and the whole of the gas 




goneratetl collected in a graduated jar over mercuiy. The 
(jxcess of oxygon is detcnnincd by adding a certain volume of 
Iiy<lrogon and exploding the mixture, and then the carbon 
dioxide is .-ibsorhed by caustic potash, and thus the volumes of 
the two gjises are ascertained. These volumes, together with 
the weight of the substance burnt, give data for ascertaining 
the quantity r>f water formc<l. In this way Gay-Lussac and 
Tlit'nanl analyse! no less than fifteen organic substances fr^'e 
from nitrogen, ami four substances containing this element. 
In the latter case they took the precaution of avoiding a large 
excesB of orygon in order to prevent the formation of the oxides 



METHOD OF GAY-LUSSAC AND THfiNARD. 46 



of nitrogen. Some of the analyses thus conducted are fairly 
accurate, when the calculations are corrected, this being neces- 
sary because at that time neither the true composition of carbon 
dioxide nor that of water was known. Thus corrected. Gay- 
Lussac and Th^nard's numbers for the percentage composition 
of sugar are as follows. The results calculated from the formula 
are added for the sake of comparison. 

Found. Calculated. 

Carbon 41-36 4210 

Hydrogen .... 0-39 6*44 

Oxygen 51'14 5r46 



98-89 100-00. 

This method, however, did not yield satisfactory results in 
the case of very volatile bodies, and the composition of these 
substances had to be determined, as before, by eudiometric 
methods. 

We are indebted to Saussure for improving this branch of 
analysis, and for determining accurately the composition of 
several compounds, such as that of alcohol.* He also analysed 
non- volatile bodies, some of them with great exactitude, by com- 
bustion in oxygen, determining the volume of this gas needed 
for the combustion, as well as that of the carbon dioxide formed.* 

41 Berzelivs's Method. Saussure's method would probably 
have come into general use had not Berzelius* published in 
1814 his much more exact method for the analysis of organic 
bodies. It has already been stated in the introduction that 
Berzelius began this investigation with the view of ascertain- 
ing whether organic bodies obey the same laws of chemical 
combination as those which regulate the formation of in- 
rirganic substances. Adopting Lavoisier's plan, he absorbed 
the water and carbon dioxide formed by the decomposition, 
determining their amounts gravimetrically. Like Gay-Lussac 
and Thdnard, he employed potassium chlorate as an oxidising 
agent, reducing the violence of its action by mixing it with 
ten times its weight of common salt. At the closed end of 
his glass combustion-tube he placed some of this mixture of 

* Ann, Chim. Ixxviii. 57. * Bibl Britan. Ivi. 333. 

> Thomson's Ann, Phil. [4], 401. 



ULTIMATE ORGANIC ANALYSIS. 




commoii salt and 
potassium chlorate ; 
then came an intimate 
mixture of the sub- 
stance \vith the same 
oxidising material, 
whiJst the front por- 
tion of the tube was 
filled with the oxidis- 
ing substance alone. 
The open end of the 
tube vaa drawn out 
to a long point and 
the whole placed in a 
furnace (Fig. 4), in 
which it was heated by 
charcoal and placed in 
the position indicated 
in the figure. For the 
sake of precaution the 
tube was surrounded 
by a coating of copper 
foil fastened with iron 
wire. The open end 
was then connected 
with a light glass re- 
recciver (a), which in 
its turn was joined to 
the tube B, contain- 
ing calcium chloride, 
which served to absorb 
the water not con- 
densed in A. The 
carbon dioxide formed, 
together with the ex- 
cess of oxygen, was 
collected over mercury 
in the bell-jar contain- 
ing a small glass vessel 
filled with caustic 
potash. In canying 
out the experiment. 



BEKZELIUSS METHOD. 



the front end of the 
tube was first heated, 
and the fire gradually 
extended to the fur- 
ther end, the screen 
F being gradually 
pushed back. The oxy- 
gen evolved at the 
end of the operation 
served for the pur- 
pose of driving the 
combustion - products 
leftin the tube through 
the absorption vessels. 
The increase in the 
weight of the vessels 
A. and B gave the 
weight of the water 
formed, and that of 
the vessel c the 
amount of carbon di- 
oxide. This method 
is not ai^licahle to the 
case of nitrogenous 
bodies, inasmuch as 
oxides of nitrogen 
are then formed which 
are absorbed by the 
caustic potash. Be- 
sidea, the method is 
liable to various other 
errors which render 
an exact (leteriiyiiia- 
tion of hydrogen and 
carbon impossible. If 
we desire to obtain an 
idea of the accuracy 
of this process, the 
analydcal numbers 
obtained by Berzelius 
must be recalculated, 
inaBmuch as inexact 




4fl ULTIMATE ORGANIC ANALYSIS 

atomic weights were employed by Lim. If this be done, we 
obtain the following numbers for the percentage composition 
of sugnr : 

Carbon 427 

Hydrogen 6*5 

Oxygen 508 

100-0 

43 Lichiijs MdJud. To Liebig belongs the singular honour 
of having so completely perfected and simplified the process of 
organic analysis that his method is used at the present day 
almost xinaltered. The labour which this investigation involved 
was however so great that it was many years (1823-1830) before 
it was completed, and the potash appiratus in the form in which 
it is now used, was not described until 1831.^ From this time 
forward he was able, with the help of his piipiia. to carry out 




Fio. 6. 



the nomerous important investigations which gave to the Qiessen 
laboratory a world-wide reputiitinn. 

As an oxidising agent, Liebig employed cupric oxide, CuO, a 
substance which lind beon used by Gay-Lussac and Thiinard in 
their analyses of nitrogenous substances. This compound is 
also oniplnycd for the qualitative detection of carbon and 
hydrogen, inasmuch as, when, in the perfectly dry state, it is 
ignited with an organic substance, the above elements unite 
with its oxygen to form carbon dioxide and water, the presence 
of which can be readily deticted. 

' Pngg. Ann. 



LIEBIG'S ORIGINAL METHOD. 



49 



Liebig's original combustion apparatus is shown in Fig. 5, 
whilst Fig. 6 exhibits the form in which at a later time it 
became generally adopted. It consists of the eombustion-tubo 
(Fig. 7) made of difficultly fusible glass, drawn out at the closed 
end to a fine point. This is filled in different ways according to 
the nature of the body undergoing combustion. If it be a solid, 
not too volatile or hygroscopic, the following method described 




flG. 7. 



by Liebig ^ miiy be used : — A small quantity of finely-divided, 
and previously ignited, black oxide of copper which has been 
cooled in a closed vessel is first brought into the combus- 
tion-tube to the point c ; some more of this oxide is then 
placed in a small porcelain mortar, and to this from 0*2 to 0*3 
gram of the substance is added. This is then covered with 
more oxide, and well mixed by means of the pcstlo. The 




Fio. 8. 



mixture is next filled into the combustion-tube up to the point 
6, and the mortar rinsed out with more oxide, and this also 
brought into the tube, which is then filled, though not com- 
pletely, from the point a with pure copper oxide. The length 
of the la.st layer of pure oxide depends on the combustibility 
and volatility of the substance. If an easily volatile substance 

' For furtb«»r details of this method we must refer to Frcscnins's Quantitative 
Amaiffn's, i>. 455, § 174, sixth cd. 

VOr* III. K 



50 



ULTIMATE OKGANIC ANALYSIS 



has to be burut, or one which, ou heatiug, gives otf large 
quantities of combustible vapours, the column of oxide must 
be longer than in other cases. The tube is then laid flat on 
the table and gently tapped, so that a free passage for the pro- 
ducts of combustion is left above the surface of the copper oxide. 

Inasmuch as copper oxide is a very hygroscopic substance and 
may, thercf(.)re, have absorbed moisture from the air during the 
process of mixing, this moisture must be removed when an exact 
determination of the hydrogen is required. For this purpose 
the tube, prepared in the way described, is placed in connection 
with the exhausting syringe (p, Fi'(. 8), the second opening of 
which is joined to a U-tube (t) containing chloride of calcium. 
The combustion -tube (ah) is warmed in a wa tor-bath or sand- 
bath, then exhausted, and dry air allowed to enter, and this 
operation repeated several times. 

43 In order to avoid this tedious dessicating process, the sub- 
stance may, according to BuUvSen's proposal, be mixed with the 



O 



Fio. 



h 

Oh. 




Fi(t. 10. 





¥u. 11 



Fi«: 1-J. 



oxide of copi)er in tlie tube itself. This is etfectod by means of 
a copper- or hrajs-wire bent at the end like a corkscrew (Fig. 9), 
a vertical and, at the same time, a rotatory motion being given 
to the wirii. The tube is then placed in the combu.stion-furnaco. 



LIEBIG'S IMPllOVKD METHOD. 61 




closed by a soft bored cork, through which passes the end of the 
chloride of calcium tube (Fig. 10), this being employed for the 
abrorption of the water produced. Another form of such a 
tube is shown in Fig. 11. The carbon dioxide is collected 
in a Liebig's potash-bulb filled 
with a concentrated solution of 
caustic potasli (Fig. 12). Ano- 
ther form of this apparatus is 
shown in Fig. 13. All these 
forms of bulbs are so arranged 
that the gas passes in single 
bubbles through the various 
bulbs, thus remaining for a Fn;. 13. 

considerable time in contact 

with the caustic potash. In order to be sure that the carbon 
dioxide is completely absorbed (for this gas is, to begin with, 
mixed with a large quantity of air), and also to prevent the 
exit air from carrying away aqueous vapour from the caustic 
potash solution, a few pieces of solid potash are placed in the 
U-tube (c) (Figs. 6 and 14) connected to and weigher! with the 
potash-bulbs. The bulbs are then connected by means of the 
U-tubes to an aspirator (v) (Fig. 6), the stopcock remaining 
open. 

In carrying out the combustion, the first point to be ascer- 
tained is that the apparatus is perfectly air-tight. This is 
usually done by first placing the Liebig's bulbs in a slanting 
position with the larger bulb uppermost, warming this until a 
sufficient quantity of air has escaped through the liquid. When 
the air in the apparatus cools, the liquid rises in the bulb, and 
there assumes a higher level than in the other part of the ap- 
paratus. If this level remains constant for a considerable time, 
we may conclude that all the parts of the apparatus are tight, 
and the combustion itself cAn now be commenced. 

The next operation is to surround the front part of the tube 
with red-hot charcoal., care being taken that the end of tlie tube 
carrying the cork is placed in such a position that in the first 
place no water condenses on it, and in the second that the cork 
does not become over-heated and charred. In order to keep the 
hot charcoal in its right place, and to prevent the further por- 
tions of the tube from becoming heated before the proper time, 
the iron screen F (Fig. 6) is used. This is gradually pushed back 
as the front portions of the tube have become red-hot. More 

E 2 



62 ULTIMATE ORGANIC ANALYSIS. 



charcoal is now added, and the process is continued until the 
whole of the layer of copper oxide is red-hot. The portion con- 
taining the substance is now very carefully and gradually heated, 
80 that whilst the combustion is going on, not more than one or 
two bubbles of gas pass every second through the potash-bulbs. 
When the whole of the tube has been surrounded by red-hot 
charcoal, and as soon as the evolution of gas ceases, the potash- 
bulbs are placed in a vertical position, the charcoal removed 
from the drawn-out end of the tube, and the screen placed in 
front of the point. Owing to the gradual cooling, and to the 
absoq)ti<^n of carbon dioxide, the potash solution will now be seen 
to pass back into the large bulb. When this is filled with liquid, 
and the pressure within the apparatus being, therefore, somewhat 
less than the atmospheric pressure, the pointed end of the tube 
is broken by means of pliers. The potash-apparatus is now 
brought back into its original slanting position, and, by means 
of the aspirator, air is drawn through the apparatus in order to 
allow the whole of the carbon dioxide and aqueous vapour to 
pass through the absorption vessel. In order to be quite sure 
that in this operation none of the carbon dioxide produced by 
the combustion of the charcoal liruls its way into the combustion- 
tube, a long, closely-fitting glass tube is dropped over the open 
point of the combustion-tube. Sometimes, instead of connecting 
the tube with an aspirator, air is drawn through the potash- 
bulbs by the mouth, by means of a bulb-tube and caoutchouc. 
The arrangement, when this ])lan is adopted, is shown in 
Fig. 14. As soon as the bubbles passing through the potash- 
apparatus no longer diminish in size, tlie current of air is 
stopped, and the absorption vessels are ramoved, placed in the 
balance case, and, after they are completely cold, their weight 
ascertained. 

Difficultly volatile and non-volatile liquids are w^eighed out in 
short glass tubes open at one end. These are dropped into the 
combustion-tube containing some copper oxide, more oxide 
added, and then the liquid allowed to run out of the tube into 
the oxide of co])per by cirefully sloping the tube. Volatile 
liquids must bo w«»ighed out into a small weighed glass bulb 
having long (»nds. One end is then broken ofi', an<l the end, 
to]r(»tlu.'r with the bulb, alloweil to fall into the combustion-tube, 
which is then iiHe<l with oxide of copper. The front of the tube 
is first heated to redn(»ss, and afterwards the jwrtion in which the 
bulb is placed, so that tlu; li<juid is driven out into the oxide of 



I.IKBIG'S METUODS OF COMBrsTION -ANALYSIS u^ 

coiiper. The combustion is tbcu allowed to proceed in the 
urdinary way, 

lo his analyses of sugar, Licbtg obtained the following 
results, which agree suflicieDtly well with the theoretical 
numbers whea they arc re-calculated with the present atomic 
weights ; 

Carbon +171 

Hydrogen 645 

Oxygen 51-8* 

100 on 




44 Oas Coiiibastiun-fimmces. The use of charcoal has the 
advantage that the temperature at the various parts of the tube 
can be readily controlled, cither by removing or by fanning the 
burning charcoal. On the other hand, its employment is accom- 
paniod by several disadvantages, which led to the proposal to 
replace charcoal by alcohol lamps. A furnace of this kind 
constructed by Hess came into use, but was soon superseded 
by gas combustion-furnaces when Bunseti introduced his non- 
luininiius gas-burner. An ohl form nf gas-furnace introduced by 



61 ILTIMATK OltGAXIC ANAIA'SIS. 

V. Babo is sliowii in Fijj. lo. Krlciim oyer's furnace exhibited 
iu Fig. 16 is luucli used at the present day. Its arrangement 
13 reailily understood by refercDce to the figure. In order to 
protect the combustion- tube front tlie direct action of the flame, 
it is generally placed in a trough made either of fireclay, or of 
iron lined with some calcined m:^Jnesia, and, for the purpose of 
tlu-owing the hot gases of the flame on to the top of the tube. 




tile;* ait.' pliRcl ■in tli:- sides and top of tlie furnaci.'. Erlenmcycr's 
furnace iIih^s imt burn nnifh gju<, but ;;reit care must lie taken in 
h<-atiij},' tin- tuln-, as it casilv < r,.i-ks unL-ss the temiH.'ratwre be 
very;,'Ta,l.i,'.llyrrus<d. 

This risk is much Irs-sencil in Ilofinaiin's form of furnace' 
(b'igs. 17 and IS), in which a wcll-ditfnscd radiant heat, similar 



GAS COMBUSTION-FURNACES. 



65 



to that obtaioed fruin red-hot charcoal, is produced by the igni- 
tion of heated fireclay cylinders. The hollow cylinders are fixed 
upon fish-tail gaa-biirners, and are closed at the top, the sides 
being punctured with a large number of small opeuinga, at 




which the gas burns mixed with air. In order to concentrate 
the beat, plates of fireclay are placed at the sides and top of 
the furnace. 

Another form of combustion-furnace now much in vogue is 
that proposed by Glaser ' mi<1 shown in 
Fig. 19. It was first described by Donny, 
and the combustion-tube is heatid by 
means of perforated pieces of iron shown 
ID the figure, forming a trough in which 
the combustion-tube lies wound round with 
iron gauze. Tlie tube is heated partly by 
conduction from the hot iron and pitrtly by 
the gas which burns through the perfora- 
tions. Perforated clay covers arc employed 
for raising and equalisinjj the temperaturt'. 

45 Uomhustion in a Viirrejit of O.i-ygcn. When the combustion 
is performed accordinjj to Liebig's original nietJiod, it sometimes 
happens, especially in the case of bi:dius riuli in carbon, that 
some of the carbon is deposited on the upper part of the tube 
or even upon the reduced metallic copper, and this is otiiy m- 
compietcly burnt v/hen air is passed over it. In order to avoid 
' An.i. iiitm. Pkarm. Kuppl. vii. -IIS. 




66 ULTIMATE ORGANIC ANALYSIS. 



this source of error, some pieces of fused potassium chlorate, or 
better, perchlorate, may be placed at the end of the tube, from 
which a current of oxygen is evolved at the end of the operation. 
When every precaution is taken, the combustion carried out in 
this way yields satisfactory results. Thus, for example, the per- 
centage of carbon ought never to be more than O'l to 0*05 below 
the theoretical amount, whilst the hydrogen should not be more 
than about 0*2 per cent, in excess of theory. By this plan, how- 
ever, a new tube must be employed for each combustion, and 
hence it was long ago proposed to conduct the combustion in a 
stream of air or oxygen, and this method is now generally adopted. 
Fig. 19 shows the arrangement of an apparatus for carrying out 
a combustion of this kind. A tube open at both ends is used ; 
one end is connected with the absorption-tubes, and the other 
with a drying apparatus (a), through which either dry air or dry 
oxygen can be pxssed. The part of the tube near the calcium 
chloride tube is filled to two-thirds of its length with granulated 
copper oxide, behind which the substance to be analysed is 
placed in a platinum or porcelain boat. In front of, and in 
connection with the absorption-tubes, is placed an aspirator (ii), 
in order to ensure the passage of the products of combustion 
through the absorption-tubes, and to prevent them by any 
chance from passing into the drying apparatus. After the 
copper oxide has been heated to redness, the substance is gra- 
dually ignited, a slow current of air being at the same time 
pissed through the apparatus from the gas-holder, in order to 
carry the products of the combustion into the absorption- tubes. 
As soon as the whole tube is red-hot, the current of air is 
changed for one of oxygen. By this means any carbon left in 
the platinum boat is completely burnt, and all the reiluced 
copi)er is re-oxidised. This method is very convenient, as after 
each combustion the apjxaratus is in exactly the same state as it 
was before the experiment ; and as soon as it has cooled down a 
new combustion may bo commenced. 

According to this plan the whole of the apparatus is well 
dried before the combustion, and henco we might suppose that 
the hydrogen determination v.ould be more correct than by 
the older process in which the hygroscopic copj)er oxide is 
exposed to the air. Experience has, however, shown that this 
is not the case, although no satisfactory expltmation for the fact 
has been given. ^ 



COMBUSTION IN A CURRENT OF OXYGEN'. 67 




58 ULTIMATE ORGANIC ANALYSI*5. 



Another similarly unexplained occurrence in such combustions 
is that that the first analyses are ahnost always incorrect, and 
hence this method is to be recommended chiefly when a large 
number of analyses have to be made quickly one after the 
other. It is then ailvisable to make several combustions of 




Fig. 20. 

some such substance as sugar, for the purpose of getting the 
tube into order, and as soon as a correct analysis is obtained the 
apparatus is known to be in the right condition. In view of the 
fact that the current of gas is constantly passing through the 
tube, this method requires much more continued attention than 
the combustion in closed tubes ; and this is especially the case 
when easily volatile bodies, or bodies which evolve a large 
([uantity of gaseous products, aie burnt. On the other hand, 
the passage of a current of oxygen at the end of the operation 
is a guarantee of the complete combustion of the substance. 
For the above reasons combustions are carried out in some 
laboratories in a close<l tube, and at the end of the operation 
a, current of oxygen is passed over it, the end of the tube being 
drawn out in the fonn shown in Fig. 20. The tube is filled, as 
in Liebig's or Bunsen's method, with the oxide of copper 
substance, and the combustion carried on in the way already 
described. As soon as no further bubbles are seen to pass 
through the potash apparatus the burners at the end of the 
tube are turned down, and this end when cold joined to an 
oxygen gasometer by a caoutchouc tube. The closed end of 
the combustion-tube is then broken by squeezing with pliers, 
and the oxygen allowed to pass slowly throui^h the tube until 
the whole of the air has been displaced. 

46 CombwUion of nitrofjencus substances. It has alreiuly been 
mentionod that in the combustion of nitrogenous bodies, oxides of 
nitrogen may be formed ; these will be partly absorbed by the 
water and partly carried forward into the potash. It is to Gay- 
Lussac that wo owe the suggestion of a method by means of 
which carbon and hv<lroi:on contuned in nitro^jenous bcxlies can be 
aocwM|y|^6temnn('d. Ah has ]>een stated, he en^.ployod copper 




COMBUSTION OF NITROGENOUS SUBSTANCES. 59 

oxide as an oxidising agent, and in order to prevent the forma- 
tion of oxides of nitrogen finding their way into the measuring 
apparatus he filled the front part of the tube with copper turn- 
ings. Gay-Lussac carried on his combustion as we do now, and 
in 1815 he succeeded in determining the composition of hydro- 
cyanic acid, cyanogen gas, uric acid, &c. At a later date this 
method was perfected in the classical investigation by Gay- 
Lussac and Liebig on the fulminates. 

If a nitrogenous substance has to be analysed, the tube is 
filled in the usual way, a layer, of from 15 to 20 centimetres in 
length, of metallic copper being placed in the front of the tube. 
For this purpose either copper turnings may be employed, or the 
metal obtained by reduction of the oxide in hydrogen. Some- 
times a spiral of copper wire, or, more conveniently, a cylinder 
of rolled- up copper gauze is used. The metal must be heated 
to -bright redness before the combustion of the substance is com- 
menced, in order to insure the complete decomposition of any 
oxides of nitrogen which may pass over. 

47 Comhustion of Bodies containing Sulplmr. Carbon com- 
pounds containing sulphur yield on combustion sulphur di- 
oxide, and this would of course be absorbed by the caustic 
potash. In order to prevent this, Liebig and Wohler * proposed 
to place a small tube containing dried lead dioxide or manganese 
dioxide between the chloride of calcium tube and the potash- 
bulbs. In passing over these oxides, the sulphur dioxide is 
oxidised, the sulphate of lead or of manganese being formed. 
Carius ^ proved, however, that when a substance which contains 
much sulphur is thus burnt, the oxides of sulphur are not 
wholly absorbed, and Buiisen has observed that the above per- 
oxides may absorb some carbon dioxide. Hence it is advisable 
to burn bodies containing sulphur by means of lead chromate, a 
substance which was first used in organic analysis by Berzelius' 
in 1838 for the purpose of preventing the formation of carbon 
monoxide in the combustion. If care be taken not to heat the 
front part of the tube too strongly the whole of the sulphur 
dioxide remains, in this case, in the combustion-tube in the 
form of lead sulphate. 

48 Use of Lead Chromate in Combustions. Lead chromate is 
aUo employed in sevenil other cases instead of copper oxide. 



* jinn. Pharm. xxvi. 270. ' Ann. Chew. Phami. cxvi. 28. 

^ roj/7. Ann. xliv. 301 



60 ULTIMATE ORGANIC ANALYSIS. 



For the purpose of preparing this compound a solution of lead 
acetate is mixed with one of potassium dichromate, the pre- 
cipitate well washed, and the dried substance fused at as low a 
temperature as possible, and powdered after cooling. Lead 
chromate possesses an advantage over copi>er oxide in not 
being hygroscopic. It also fuses readily, and hence it is especi- 
ally valuable for the analysis of bixlies very rich in carbon 
or of those from which carbon readily separates, and in these 
cases it is advisable to add to it a small quantity of potassium 
' dichromate. It is also used for the combustion of organic salts 
of the alkalis and alkaline earths, as these when heated in an 
atmosphere of carbon dioxide leave a residue of carbonates. 

When the sjime load chromate has been fre([uently employed 
for combustion, and a large quantity of chromic oxide and 
metallic load has been formed, it may readily be oxidised by 
moistening with nitric acid, drying and fusing. 

If an organic substance containing an element of the 
chlorine group be burnt with copper oxide it may happen that a 
iwrtion of the chlorine is set free and this may condense in the 
absorption-tubes. In order to avoid this, lead chromate is used, 
in which case the haloid salt of lead is formed. Such a com- 
bustion may however be carried on with copper oxide if a spiral 
of metallic copper bo placed in the front of the tube, and if 
tliis bo heated not too strongly. As the above cuprous com- 
])0unds are however tolerably easily volatile, they are sometimes 
carried forward into the chloride of calcium tube.^ Moreover 
those halogen elements may be given off from the cuprous salt 
when oxygen is passed over the substance. Hence it is better 
in such cases to employ a spiral of fine si Ivor wire or silver foil 
instead of copper.- 

When a comiMMiml containing mercury is to be burnt, a cop]Xir 
spiral is also placed in front of the tube and this must be only 
very giintly heati'd, otherwise the deposited mercury may be 
volatilised ami pass into the weighed tube. 

49 ^h'fjunic AfH//i/sis hi/ mt'an.-i nf Platinum. This metal in its 
finely-divi<lod st-ite is well known to i>ossess the power of con- 
densing oxygon in lar^^e (luantity, and of giving it up again to 
rondmstiblo l)«Mlies. l'^jH)n this tact F. Kopfor'* has foun<led 
a method of analysis capable of very gtMiornl application, and 

' St iililiT. .III/'. f%in. Pluimi. Ixix. :Vj5. 
- IvMut. 'A'iishi'. ,t,\,i}, n„',n, ii. UJi. 
' J'nirtt. t'hrni A'"-, xxix. «>•;•». 




ORGANIC ANALYSIS BY MEANS OF PLATINUM. 



61 



characterised by its exactitude, especially in the determination 
of hydrogen, as well as by its simplicity and convenience. The 
combustion is carried on in a current of oxygen gas in a tube 
open, at both ends about 1*5 cm. in diameter, Fig. 21. At a^, 
a,2 and a^ are placed plugs of asbestos wound round with fine 
platinum wire, of which the end ones sit loosely in the tube, 
whilst fltj is fastened more firmly, and this, in order to prevent 
the passage being stopped by volatile bodies, has a prismatic 
form. The space between a^ and a^ is filled with an intimate 
mixture of about 10 grams of platinum-black^ and the re- 
quisite quantity of freshly ignited and woolly asbestos. This 
mixture, which is easily obtained by simply shaking up the 
two materials in a bottle together, possesses a large amount of 



«em.^ 



so cm 



10 cm 




n 



I • 



It I ■ 

item 



I 



Fig. 21. 



30 cm 



surface for the mass of the body, and therefore acts very quickly. 
Between a^ and a^ is placed the boat or tube containing the 
substance. The combustion-tube between a^ and h is sur- 
rounded with a double cover of brass wire gauze, whilst that 
between h and c is placed in a trough of double wire gauze. 
Either air or oxygen may be employed for the purpose of carry- 
ing on the combustion. For purifying and drying the gas 
Kopfer used a very convenient apparatus. The gases pass 
first through a Liebig's potash-bulb containing a fifty per cent, 
solution of caustic potash, and from this so small a quantity of 
water evaporates that for the purpose of drying only short 
chloride of calcium tubes are employed, and these may be used 
for a len'jth of time. The combustion furnace is composed of 



* In order to prepare this substance, a qnantity of platinum chloride contain - 
in;? about 10 grains of metal is heat<'d to boiling with 25 grams of ])ure caustic 
f.otash, dissolved in 400 cc. of water. This is then added to a boiling solution 
of 10 grams of grape sugar in 400 cc. of water and the whole boiled for a few 
minutes. 



62 ULTLMATK ORGANIC ANALYSIS. 



two moveable boxes of sheet iron of which the first carries four 
burners, and the last only one (/), moveable in a slot (Fig. 22). 
In order to carry out the combustion the tube is first filled w^ith 
oxygen, and then the current so regulated that two bubbles 
pass through per second. At this point the four front burners 
are lighted, and the substance heated, beginning from c (Fig. 22). 
in the direction shown by the arrow, for the purpose of allowing 
the greater part of the volatile pro<lucts to condense between 
flg and h, a small portion only, passing over the heated 
platinum and being completely burnt. The position of the 
burner / is then so placed that the combustion goes on regularly. 
When a quantity of carbon has separated out, or when diffi- 
cultly volatile substances have sublimed between the parts a 
and />, a piece of wire gauze is placed over the tube, and this 
portion is heated to redness. When the combustion is complete, 
the oxygen ij replaced by air, and a new analysis may then be 
begun as soon as the tube has cooled. In the case of very easily 
oxidisable substances a very vigorous combustion often takes 
place about a^, the platinum-b!ack being thereby heated to 
redness. In such a case the oxidation must be regulated by 
pushing the burner in the opposite direction to that shown 
by the arrow. 

Should t!ie substance contain the elements of the chlorine 
group, fifteen ^;rams of thin silver foil cut into small four-sided 
pieces must be mi.xed with the platinum -asbestos. After the 
combustion it is then ignited in a current of hydrogen in which 
the tube \?> allowed to cool, and lastly it is heated in a rapid 
current of air when the apparatus is ready to bc» employed for 
a new analvsis. 

Compounds which contain nitrogen or sulphur are burnt by 
bringing into the front part of the tube a layer of lead dioxide * 
about 10 cm. long, and surrounded by an air-bath, the bottom of 
which consists of three pieces of brass wire gauze, and the top of 
which contains two such layers whereby the temperature is 
regulated. This is showTi in Fig 23. It is then heated for an 
hour to a temperature of 150*" to 200°, pure carbon dioxide 
passed through, and histly this replaced by dry air. During 
the combustion the lead dioxide is kept at the same tempera- 
ture, when the sulphur is entirely held bjick in the fonn of 

' This is l>ost obtaiii(>«l l»y boiling pure rod lead with nitric acid. The residue 
i8 first wiwhed with hot dilute nitric arid, and then >iith hot water, and, after 
drying on a wator«bath, is broken into small pieces. 



KOPFER-S METHOD OP COHBUSTIOX-ANALYSIS. C3 




64 ULTIMATK OliGANIC ANALYSIS. 

8iil])hatc, au<l nitrogen iu the foim uf uitrute. If, in adJitiou 
to these, the substanco contiiius the elements of the chlorine 
group, asbestos contaiiiiii',' silver foil must likewise be employed. 




DETERMINATION OF NITROGEN. 



50 Detection of Nitrojien. ^lany orguiiic bxiios coiitaiiiiiig 
nitri>gen, when hcateil with an alkali, evolve either ammonia or 
a compound ammonia. Tlie pi-esi-iice i>f these substances may 
be (leteeteil by their smull, by tlicii- alkaline reaction, and by 
their iiroiH.Tty of yieliling a thick eloml when l>rouj;lit into 
contaet with hydriH-hloric acid. The presence of nitrogen can 
thus bo readily detected. If however the i^nantity of nitrogen 
be but small it may tVius eacajK- ileti!Cti<>n. Moieover a large 
iiumhtT "f carbon eomixmnils exi.-it of artificial origin, obtained 
by the action of nitric acid or of the oxide* of nitrogen, and 
tlie.-ie do not, as a rule, yield ammonia when ignited with an 
iilkali. 

The smallest trace of nitro;jen can however bo cleteoted in 
every case by a niethinl iin)i>osi-d by Las.iaignc' Kor this purpose 
tho body is heated in a small tube with metallic sudium. If 
the suhhtancc W explosive it nuist bo mixed Inloreliand with 



ESTIMATION OF NITROGEN. 05 



dry carbonate of soda. In most cases a slight detonation takes 
place with separation of carbon. The mixture is then heated 
more strongly in order to volatilise the sodium, the mass allowed 
to cool, the residue dissolved in water and filtered. The filtrate 
which contains cyanide of sodium is then mixed with a solution 
of ferrous sulphate which has undergone partial oxidation in the 
air, and acidified with dilute sulphuric acid. If a large quantity 
of nitrogen be contained in the organic body, an immediate 
precipitate of Russian blue is thrown down. If, however, 
only smaU traces of nitrogen be present, the acidified liquid 
becomes green, and after a time a blue flocculent precipitate 
is observed. 

51 Estimation of Nitrogen, For the purpose of determining 
nitrogen quantitatively, two methods are employed. It may 
be obtained either in the form of ammonia or of a compound 
ammonia, or it may be liberated and the volume of nitrogen 
gas determined. 

Will and VarrerUrapp' s Method, The first method, for which 
we are indebted to the above-named chemists,^ is by far the 
simplest, and it is, therefore, employed in all those cases in which 
it is possible to do so. It depends on the fact already mentioned, 
first observed by Dumas, that nitrogenous bodies when heated 
with an alkali form ammonia, the carbon being oxidised and 
the nascent hydrogen uniting with the nitrogen. 

# 

C + 4K0H = CO, + 2K,0 + 4H. 



K an excess of hydrogen be formed at the same time, it is 
either evolved as such or in the form of hydrocarbons. Wohler 
and Liebig proposed to employ this for the determination of 
nitrogen, and the above-named pupils of Liebig worked out 
the process in the exact form in which it is now so much used. 
Soda-lime is employed as the alkali, as it does not attack the 
glass. This is obtained by slaking two parts of quicklime with 
a solution of one part of caustic soda and gently igniting the 
mixture. In the process of analysis, soda-lime is brought into 
a small combustion tube (a, Fig. 24), and the substance well 
mixed with it in the tube, which is then filled up to the end 
with pure soda-lime. The tube is then tapped so as to open a 

* Ann. Chcm. Phann. xxxix. 257. 

V 



ULTIMATE OKGANIC ANALYSIS. 



channel at the top, and attached to tlie bulb-apparatus (b), 
coDtainiug dilute hydrochloric acid, so airangod that the liquid 




Kio. ai. 



can neither be blown out by tlie rapid currant of gas nor drawn 

back into the tube, if an absorption should take place. Auotlier 

bulb-apparatu3 which perhaps secures this 

' "^ end more certainly has been proposed by 

/^ / Arendt and Knop, and shown in Fig. 25. 

^JP' / When the wlinle apparatus is arranged, 

Cv Lj *'"^ front layer of soda-lime is ignited, and 
T^^l^y^ the mixture of the substance with soda-lime 

Fiii. 2S, is then gradually heated. At the end of the 

operation tho point is broken, and air drawn 
through the ap]>nratus cither by means of the mouth or by an 
aspirator, in older to bring tlie whole of the ammonia into 
the hydrocldoric acid. The residue left in the tnbe should 
be white, and to effect this, tlie tube rcijuires to be jiretty 
strongly heated so that any carbon containing nitrogen, or any 
cyanogen compounds, may be completely burnt. 

Nitrogenous liquids are weighed out in bulb-tubes and treated 
in the same way as in the carbon and hydmi^en deter mi nation. 
In place of soda-lime a mixture of oipial jiarta of iwiwdorcd 
quicklime and soda may, in many cases, be cmpJoyed.' In case 
of bodies which contain large quantities of nitrogen, and which 
therefore evolve a large quantity of ammonia, it n:ay happen 
that, in spite of all care, the acid passes back into tho red-hot 
tube. This may Ive jirevented simply by mixing the substance 
with some sngar in order that the amnjonia may l>e dilutcil 
with hydrogen or some hydrocarbon. The hydrochlmic acid 
is then eva|«. rated on a water-bath ivitli an excess of )>latini(; 
chl'>ri<l.', and the residti-! thrown on ti. ;i rtlt.r and washed with 



DETERMINATION OF KITHOGKN. 67 

ether to which only a few drops of alcohol liavo boeu added, 
because Hofmann has shown that tlio double plutiuum salts of 
the compound ammonias are frequently rather soluble in alcohol. 
The residue on the filter is then dried at 100° and weighed. 
It ia then ignited and the weight of the residual platinum 
ghtaiued. From this it is easy to calculate the quantity of 
nitrogen, because all theso platinum double salts coutain two 
atoms of nitrogen to one atom of the platiimin. The comparison 
of the weight of the double salt with that of platinum is in 
many cases of importance, fur by this means we ascertain 
whether ammonia or a compound ammonia has been formed. 

52 Lubig's Etlative Method. It has already been stated that 
Gay-Lussac was the first to employ copper oxide aud metallic 
copper in the analysis of nitrojjenoiis cuinpoiiiid;f. Ho collected 




t'lu. 213. 

the products of combustion over mercury, aud determined the 
Tolame of the carbon dioxide aud thut of the free uitii';,'oii by 
absorbing the first of these gases with alkali. U:iy-Liia^io 
and Liebig, in their investigation on fulminic acid, porfirtod 
thifl method, and the latter founded on this bis niethoil for 
the relative determination of nitrogen. For tliia purpose an 
nnweigbed quantity of the body, mixed with about fifty times 
its weight of oxide of copper, is brought into the conibnstion- 
tabe, which is closed at the end and half filled with the mixture. 
lu the next fourth part of the tube, pure oxide of copper is 
added, the last quarter being filled with metallic copper and the 
Open end of the tube being furni.shed with a gas-delivery tube. 
"Die metallic copper is first heated to re(hiess ; next the furtlier 
portion of the combustion-tube is heatcfl, in onler to expel the 
nhole of the air contained iu the tube by means of the ga.'*es 
evolved during the combustion ; the ignition ia slowly earned 
fiirward, and the gases are collected in small graduated tubes 
■»ver mercury, as shown iu Fig. 2G. In order to ascertain the 



G3 



ULTIMATE ORGANIC ANALYSIS. 




I'lo. 27. 



relation between the carbon dioxide and nitrogen in this gaseous 
mixture, the tubes are brought one after the other into a cylinder 

filled with mercury (Fig. 27), 

and fixed in such a position 

that the level of the mercury 

inside and outside the tube is 

the same. The volume of the 

iraseous mixture is then read 

oflf, a small quantity of caustic 

potash solution blown into the 

tube by means of 

the pipette (Fig. 28), 

and after this has 

been moved slowly 

up and down in the 

tube, the whole of 

the carbon dioxide 

is absorbed. As soon 

Fig. 28. ^^ ^^^^ ^^ eflfected, 
the level of the 
mercury inside and outside is again equalised, and the volume 
of the nitrogen read off, and thus the relation l)etween it and 
the carbon dioxide ascertained. The first tube may contain 
a small ([uantity of air ; the later ones, on the other hand, 
ought, if the experiment has been properly conducted, to yield 
identical results. 

If the amount of carbon contained in the substance has l)een 
previously determined by combustion -analysis, it is easy to 
ascertain the absolute amount of nitrogen from the relative 
volumes of the carlxm dioxide and nitrogen. This method of 
Liebig's for the relative determination of nitrogen is simply 
and easily carried out, but only yields, as he himself remarks, 
accurate results when the substance does not contain more than 
four at<^>ms of carbon to one of nitrogen. Moreover, it possesses 
the disiid vantage common to the t>ther relative methods,^ that 
the determiijation of the nitrogen is entirely dependent on that 
of the carbon. 

S3 BiniM'ii'.^ lulntivr Mdhod. Bunsen ^ has proiX)sed another 
method of nitrogen determination esjKJcially valuable for the 

* Marrhnml, JoHrn. Pr. f'hem. xli. 177; Gottlieb, Ann. Chnn, Pharm. 
Ixxviii. 241 : Simppon, ihid. xrv. 03. 



BUNSENS HELATIVK METHOD. 



analysis of such a substance an gun-cotton, in which the nitrogen 
can in fact not be determined by any other method. For this 





purpose about five grams of copper oxide and from 03 to 04 
gram of the substance mixed with some metallic copper arc 



lO 



TLTIMATE riHGAXIC ANALYSIS. 



placed in a combustion-tube closed at one end, about 50 centi- 
metres in length, and having a diameter of about 3 centimetres. 
The other end of the tube is then drawn out to a fine but strong 
point, as shown in Fig. 32, which is carefully fused after the 

whole apparatus has been filled with 
«lry hydrogen, and this gas has then 
been removed for the most part by 
means of an air-pump, the arrange- 
ment for this purpose being represented 
in Fig. 20. The tubes are then placed 
in an iron trough (Figs. 30 and 31), 
filled with a paste of pLister of Paris 
and water, and when after the lapse 
of about an hour this has set, the 
whole is heated to dull redness. After 
Fig. 82. cooling, the drawn out end is broken 

under an eudiometer, and the gas 
determined by eudiometric methods. 

In order to carry out these operations successfully, a con- 
siderable amount of practice and great manual dexterity are 
needed ; and hence, in those cases to which the easy method 
of Varrentrapp and Will is inapplicable, the process which is 
usually adopted is the method of the absolute determination 
of nitrogen, known as Dumas's method. 

54 Dumas Absolute Method. Into a combustion-tube, closed 
at one end, a compound is first brought which easily gives 
oflF carbon dioxide on heating. For this purpose either copper 
carbonate or white-lead may be employed. Then comes a short 
layer of copper oxide, then the mixture of the substance with 
copper oxide, and next a long layer of pure copper oxide, and 
lastly, in the front part of the tube, a spiral of metallic copper. 
By heating the further end of the tube the whole of the air 
is completely driven out, being replaced by carbon dioxide, and 
this operation may be hastened by adopting Bunsen's sugges- 
tion of placing the tube in connection with an air-pump. The 
conil)U8tion-tul>e is then fitted with a gas-delivery tube, in order 
to enable the products of combustion to pass into the graduated 
cylinder over mercury (Fig. 33). When the whole tube has been 
i.jnite(l, the gaseous products of combustion contained in the 
tube arc driven forward by the evolution of carbon dioxide from 
the matericil placed at the end, the whole of this latter gas 
being absorbed by the caustic potash solution contained in the 



METHODS OF DUMAS AND SIMPSON. 



', BO tliat tbo resitlual gas cousists of pure nitrogen. Id 
order to determine the volume of this latter, the measuring 
tube is withdrawn from the mercury b; mcaus of a small dish 
filled witli mercury placed underneath, and brought into a high 
cylinder filled with water. The dish ia then removed, and the 
cylinder allowed to remain in position until it has attained the 
temperature of the surrounding air. As soon as the level of 
the water has become constant, the height of the menifcus is 
read off, and from this the volume of gas determined. 




A disadvantage attaches to this process, inasmuch as in the 
analysis of bodies rich in carbon it may easily happen that a 
separation of carbon takes place, which may still contain nitro- 
gen, and if this be deposited on the upper i>ortions of the eom- 
bustion-tube or on the metallic copper, it cannot be completely 
burnt. In afldition to this, some quantity of carbon monoxide 
may possibly be formed. 

55 Simpson's Method.' This method is not open to the above 
objections, and yields accurate results. It is, in fact, a 
modification of Dumas' method, and is now frequently employed. 
For the purpose of evolving carbon dioxide. Maxwell Simpson 
recommends the use of carbonate of manganese, but in place of 
this it is more convenient to employ magnesite in lumps about 
the size of a pea. A layer of about 10 centimetres of this is 
placed at the end of the tube, then a mixture of mercuric oxide 
and copper oxide, this mixture being separated from the mag- 
nesite by a plug of asbestos. In other respects the tube is 

' Chtm, Sof. Jaum. vi, 2S0, 



72 ULTIMATE ORGANIC ANALYSIS. 



filled as described under Dumas' method. The copper spiral 
should be about 20 centimetres in length, for the purpose not 
only of decomposing the whole of the oxides of nitrogen which 
are formed, but also to absorb any excess of oxygen which may 
come oflf. The portion of the tube containing the carbonate is 
first gently heated, and as soon as the evolution of gas becomes 
rapid, the front part of the tube containing the copper spiral is 
heated until all the air is driven out of the apparatus, which is 
readily ascertained by collecting the gases from time to time in 
a test-tube over mercury and adding a small quantity of caustic 
potash. As soon as the absorption is complete, the combustion 
may be proceeded with. The further end of the tube is allowed 
to cool, and the tube slowly heated from the front towards the 
back. The gases evolved are collected over mercury in a pear- 
shaped vessel (Fig. 34) containing caustic potash. As soon as 
the whole tube is red-hot, and no further evolution of gas is 
noticed, the gases contained in the tube are swept forward by 
re-heating the carbonate contained at the closed end. The 
nitrogen is next transferred to an accurately calibrated eudio- 
meter, by a process which is rendered sufficiently evident by 
Fig. 3o, and as soon as the caustic potash solution is seen to 
ascend into the capillary gas-delivery tube, no more mercury is 
poured in, and thus the exact volume of nitrogen evolved is 
brought into the eudiometer. 

Zulkowsky^ has recently described another simpler collecting 
apparatus, which avoids the use of mercury, and renders it 
possible to work rapidly. It consists of two tubes of about 5S 
centimetres in length (a and B, Fig. 36), of which the former 
is graduated, and serves for collecting and measuring the gas, 
whilst the latter is open at the bottom, and serves for filling in 
the caustic potash. Both tubes are held by means of supports 
(Kj and k) in a vertical position, and are connected with one 
another by the caoutchouc tube. Two fmall tubes {c and r^) 
are fused on to tliese tubes. The first of these is connected by 
means of a caoutchouc tube with the combustion-tube, and can 
be closed by the pinchcock /. The second small tube serves 
for letting out the caustic potash, and is also funiishcd with a 
pinchcock (r). The small bulbs // contain a few drops of mer- 
cury, and .«crve as a safety valve, in order to prevent the caustic 
potash solution from passing back into the combustion-tube in 

' Lichvjs Annnhn^ clxxxii. 206. 



SIMPSON'S NITROGEN DETERMINATION. 



case of a slow evoIutioD of gas. When a oitrogen determinatioa 
has to be made, the measuring tube is takeu out of the clamp 




K, and brought into the position shown in the right-hand figure. 
Caustic potaah is then poured in, and if the caoutchouc tube A 



74 



ULTIMATE ORGANIC ANALYSIS. 



be wide enough, this readily flows down so as to fill the whole 
of the tube. The apparatus is now connected with the com- 
bustion-tube, and the hinder portion of that tube heated so as 
to drive out the air. This is collected in the measuring tube, 




Fio. 3G. 



and is from time to time allowed to pass out by bringing it into 
the position shown at the right hand of the figure. As soon as 
the whole of the air has been driven out, the combustion is 
carried on in the usual way. The nitrogen is collected in the 
measuring tube, and the caustic potash is driven into the second 



I 

DETER^UNATION OF CHLORINE. 75 



tube, from which, in order to diminish the pressure, it is from 
time to time drawn ofiF. When the combustion has been com- 
pleted, the apparatus is disconnected from the combustion-tube, 
and brought into a situation where the temperature is tolerably 
constant, allowed to stand, the temperature of the caustic 
potash then determined, and the level of the liquids in the two 
tubes equalised by allowing the solution to flow out through 
the tube c^. The volume of the gas, thus placed under the 
atmospheric pressure, is then read off. 

In some rare cases the formation of nitric oxide cannot be 
altogether avoided in Dumas' process. It is then necessary to 
collect the gas over ferrous sulphate, and to allow for the volume 
of this gas thus absorbed.^ 

Several suggestions have been made for the purpose of 
deteruiiniug nitrogen together with carbon and hydrogen u\ 
a single combustion. The method proposed for this purpose 
by Pfliiger* can here be only shortly mentioned. He carries 
on the combustion in a vacuous space, and determines gravi- 
metrically the quantity of water formed, whilst that of the 
carbon dioxide and nitrogen is ascertained by volumetric 
measurementfi. 



DETERMINATION OP CHLORINE, BROMINE, 

AND IODINE. 

56 These elements may be determined easily and rapidly by 
igniting the substance with pure quicklime. For this purpose, 
a narrow combustion-tube about 45 centimetres long is closed 
at one end, and into this some quicklime is brought, and then 
the substance either mixed beforehand with lime or weighed 
out in a small bulb, and this is dropped on to the lime. A 
channel is next made at the top by tapping the horizontal tube, 
and then the mixture, commencing at the open end, is heated. 
When the whole has been ignited and allowed to cool, the 
contents of the tube are brought into a flask containing 
water. Care must be taken that the material is not thrown 
out by the violent slaking of the lime. The whole is then 

^ Frankland, Ann. Chem. Phann, xcix. 350. 
» Pfliiger's Arch, gcs, Phys. 1878, 117. 



7G ULTIMATE ORGANIC ANALYSIS. 



made sligJitly acid with dilute nitric acid, and the tube washed 
out first with w^ater and then with dilute nitric acid. After 
lilteriji^ and washing the residue, the halogens are precipitated 
by tsUmr nitrate in the slightly acidified solution. 

It s^^metimes happens in the analysis of compounds containing 
i^xline that this element separates out on the addition of nitric 
acid. In this case it is, therefore, better to dissolve out with 
water, to wash, and to add silver nitrate to the filtrate, and 
then tr> dissolve out the residue in acid, and add the filtrate 
to the first liquid. 

Tlie decomposition of very volatile bodies which contain 
clilorinc or bromine may be readily eflfected according to Piria's 
plan, which has been somewhat improved by Hugo Schiflf.^ 
Th<? substance is placed in a small platinum crucible with a 
uiixiurts of 1 part of anhydrous sodium carbonate and from 
4 i/j 5 fiarts of lime. It is then covered with a large crucible, 
uwl lh<5 two brought into such a position that the small crucible 
iufH iij the large one with its mouth downwards. The space 
IMw*;<'Ii the two crucibles h then filled up with the alkaline 
f/iixtiinr, the cover placed on the larger crucible, and the whole 
\it:iiUu\ it) redness. Substances containing iodine cannot however 
Uj ;irialys<;d according to this method, as calcium iodate is 
formed, but the determination of iodine may be carried out 
if W9^\\^\u\ carbonate alone be employed. 

57 CariuHS Mctlwd. In this method,- which is applicable to 
all cases in which the haloid element is easily removed, the 
siiliMtance is weighed out in thin glass bulbs. The form of bulb 
(fif wAiA Iiodi<»s is seen in Fig. 37, whilst Fig. 38 exhibits that in 
whieh liquids are contained. These bulbs are then brought 
int/i a gl/iss tube half filled with a solution of silver nitrate in 
nitric a^iid having a specific gravity of 1*2. The open end of 
the tu^ie is then drawn out to a capillary point and the liquid 
SytWivA until all air has been expelled. After this the pbint is 
tnmaX and allowed to cool (Fig. 39). The bulb is then broken by 
Amkiuy^ the tube, and the whole heated gradually in an air-bath 
(Fig, 4U), Ui a temperature varying, according to the nature of 
iUit mi\mUi\mt, from 150'' to 200^ In the case of bodies rich 
ilj carUiri which undergo oxidation with difiSculty, nitric acid 
</f %\nMtic (gravity 1*4 nmst be used, and a small quantity of 

* MbiffM Ann. cxcv. 293. 

* Ann, Chem. Pharm. rxri. I ; cTXXvi. 129. 



DETEEMINATION OF CHLORINE. 



potassium dichroniate added. As soon as the whole of the 
organic substance has disappeared, the tube ia allowed to cool, 
the capillary end is carefully softened in the gas-flame so that 



HI 



a very small opening appears, tli rough wliich the carbon 
dioxide formed is allowed to escape, but so that tlic liquid 
is not thrown forward. The haloid salts of silver which are 




f>rmed in this decomposition are then bronjiiit on to a filtor, 
together with the remains of the glass bulb, and these are 
weigh «1 togetlier. 



78 ULTIMATE ORGANIC ANALYSIS. 



DETERMINATION OF SULPHUR. 

58 For the purpose of determining sulphur in compounds 
which are not volatile, these are fused, according to Liebig's pro- 
posal/ with caustic potash and nitre in a silver basin, and the 
mass allowed to cool as soon as it has become white. It is then 
dissolved in water, acidified with nitric acid, precipitated with 
barium chloride, and the precipitate treated in the usual way. 

Volatile sulphur compounds are oxidised by a method 
analogous to that described for chlorine compounds. They are 
placed in a combustion-tube with a mixture of sodium carbonate 
and nitre, or, according to Kolbe's^ process, with potassium 
chlorate. 

Debus's * method may also be employed, in which a mixture 
of carbonate of soda and potassium dichromato is used, or that 
proposed by Otto, in which pure cupric chromate is employed, 
lu all these cases sulphates are obtained, and their amount 
determined in the usual way. 

Another good method is that proposed by Russell.* In a 
combustion-tube closed at one end, from two to three grams 
of mercuric oxide are brought ; then a mixture of the sub- 
s*mice with mercuric oxide and sodium carbonate, and lastly 
only the latter substance. The combustion-tube is then 
furnished with a gas-delivery tube, in order to condense the 
vai)ours of mercury and of water, and the combustion is carried 
on as usual from back to front. After the ignition the contents 
of the tube are thrown into water, and the solution acidified 
with hydrochloric acid. In order to ascertain that no sodium 
sulphide has been formed, a drop or two of mercuric chloride 
is added. If no dark precipitate is formed, the solution is 
precipitated with sodium carbonate. 

Lastly a method has been suggested by Carius depending on 
the fact that the substance can be oxidised in a closed tube 
with nitric acid, sulphuric acid being formctl. Sometimes it is 
necessary to add a small cpiantity of i>ola?sium dichroniate. 

' Ifatulwiirtr.i'luch^ i. 8S7. 
' IfandtrHrfrrhurh, Siipitl. 20.'». 
' Ann, C/icm, Phann, Ixxvi. 1»0. 
* i^hiart, Jourf. (%:ni. 6V. vii. '21 J. 



DETERMINATION OF PHOSPHORUS. 



DETERMINATION OF PHOSPHORUS. 

59 Organic substances containing phosphorus are ignited with 
sodium carbonate and nitre or potassium chlorate, in order to 
form a phosphate. They may also be oxidised with fuming 
uitric acid, when phosphoric acid is obtained. According to 
Carius a useful oxidising mixture is sulphuric acid and iodate 
of silver, the two being hejited with the substance to 180°. 
After the liquid has cooled and is diluted with water, it is 
filtered, and some sulphurous acid added to the filtrate, in order 
to precipitate any dissolved silver iodate, and thus a solution 
of phosphoric acid is obtained, which (as in the other cases) is 
determined in the usual way. 



DETERMINATION OF OTHER ELEMENTS. 

60 In order to determine any of the other elements (with 
the exception of oxygen), it is usually necessary to ignite the 
organic substance either by itself or mixed with nitre, or else to 
destroy the substance completely by heating it with nitric acid. 
Tlie element which it is then desired to determine is brought 
into solution in the usual way and determined by suitable 
methods. 

In the case of salts of organic acids, the metal may generally 
be determined as in its organic compounds. In some instances, 
indeed, the method employed may be simpler. This is the case 
in the organic compounds of gold, platinum, and silver, which 
only require to be ignited in order to leave the metal in the 
pure state in a condition in which it may bo weighed. 

The salts of other metals leave on ignition a residue of oxide 
or carbonate, or sometimes of the metal mixed with carbon. 
These are then brought into solution and determined in the 
osiial way. 



80 CALCULATION OF ANALYSES. 



DETERMINATION OF OXYGEN. 

6i This element is very seldom determined directly, its 
amount being usually obtained after the percentage of all the 
other elements has been determined, for if these numbers do not 
add up to 100, the difference is usually taken to be the percent- 
age of oxygen. It is however in this case absolutely necessary 
that we should know positively what other elements are present, 
and that the amount of each of these should be. determined as 
accurately as possible, for if one be overlooked, the results of 
the analysis will, of course, lead to totally incorrect fomiulaj. 

A classical example of this kind of error is that of the 
analysis of taurine, a crystalline compound occurring in the 
animal kingdom. The formula CgH^NOg was long adopted as 
expressing the composition of this substance, until Redtenbacher 
found that the body contained sulphur. The reason of the non- 
detection of the sulphur was, that both in constitution and in 
properties taurine differed from all the sulphur compounds then 
known. Moreover, the apparent truth of this formula could be 
upheld with some show of reason, inasmuch as the atomic weight 
of sulphur is double that of oxygen, and when the amount of 
the sulphur was ascertained, the formula of the substance was 
shown to be C^H-NO.jS. A method for the direct determina- 
tion of oxygen is, therefore, much to be desired, not only for 
the purpose of avoiding errors of this kind, but also because 
such a determination would serve as a valuable control of the 
correctness of the analysis. 

Unfortunately, none of the various methods which have been 
as yet proposed for this purpose have come into general use, 
and the reader is referred to the original papers in which these 
proposals arc described.' 

CALCULATION OF ANALYSES. 

6a Percentage Composition, When a substance has been com- 
pletely analysed, its j^ercentage composition is calculated. The 
following examples illustrate the nature of this simple operation. 

* Wanklyn nnd Frank, Phil, Mag, [4] xxvi. 554 ; Baunihauer, ZciUtch, anal, 
M, 1866, 114 ; I>adenl)iirg, Ann, Chein, Phann. cxxxv. 1 ; Mitscherlich, 
Ann, C3UEX. 536 : Trcticr, Zcitsch, anal. Chem. 1874, 1. 




MOLECULAR WEIGHT DETERMraATION. 81 



Example No, 1. 0*146 of a volatile liquid burnt with copper 
oxide yielded 0'449 of carbon dioxide and 0*2135 of water. 

Now as 43*89 parts by weight of carbon dioxide contain 
11*97 parts by weight of carbon, and as these numbers stand 
almost exactly in the proportion of 11 to 3, the quantity of 
carbon may be obtained by the fraction — 

0-449 X 3 X 100 ^^ ^^ 

= 83-87. 



0146 X 11 



For the purpose of obtaining the percentage of hydrogen we 
have the following expression : 

0-2135x100 
U*l4t) X 9 ~ ^^'^^• 

Hence the compound is a hydrocarbon having the compo- 
sition — 

Carbon 83*87 

Hydrogen .... 16*25 



100*12. 



Example No, 2. 0*2607 of aurin, a red colouring matter, 
yielded 0*7515 carbon dioxide: and 0*1152 water. 
Hence 100 parts contain 

Carbon 78-61 

Hydrogen .... 4*91. 

But, as these numbers do not add up to 100, and as the 
qualitative analysis has shown that it contains nothing but 
carbon, hydrogen, and oxygen, inasmuch as the substance, 
when heated, yields water on decomposition, it follows that the 
percentage composition is : 

Carbon 78*61 

Hydrogen .... 491 
Oxygen 16*48 



100-00. 

Example No. 3. (1) 0*3827 of caffeine yielded 06948 of 
carbon dioxide and 0*1800 water. (2) By Will and Varrentrapp's 
method, 0*1350 of caffeine yielded 0*2750 of platinum. 

It has already been stated that one atom of platinum 

Q 



82 CALCULATION OF ANALYSES. 



corresponds to two atoms of nitrogen, and hence the percentage 
of nitrogen is : 

0-2750 xJS^xlOO 

' U1350 X 1967 -2^*^^- 

If now the amount of carbon and hydrogen be calculated 
from the above analytical results, numbers are obtained which 
do not add up to 100, and as no other element can be detected, 
the diflference between the amount thus found and 100 must be 
the quantity of oxygen caffeine contains. Hence the percentage 
composition of the substance is : 

Carbon 49-51 

Hydrogen .... 5*22 

Nitrogen 2899 

Oxygen 1628 



100-00. 

In a deteiTnination of the nitrogen contained in caffeine ac- 
cording to Liebig's relative method, it was found that the 
gaseous mixture consisted of one volume of nitrogen to four 
volumes of carbon dioxide. Hence caffeine must contain one 
atom of nitrogen to every two atoms of carbon, and the 
percentage of nitrogen is found by the equation : 

40-51 X 14 

" 24 -28-88. 

If the amount of nitrogen be determined ajs gas, the volume 
of the dry gas is ascertained at 0"" and 760° from the well-known 
formula : 

_ viv-n _ 

760 (1 + 0-003665 x 0' 

when / signifies the tension of the vap<;ur of water. As 
we know that 1 cbc. uf nitrogen under the above conditions 
weighs 000125 gram, it is easy to dotermine the weight of 
nitrogen contained in 100 part.-^ of tlie compound. 



CALCULATION OF FORMULA. 

63 Having ascertained the pcrc(»iitage cc^mposition, the next 
point to determine is the formula of tlie compound. In the 
case of inorganic compounds the numerical relation in which 



CALCULATION OF FORMULA. 83 



the various constituent atoms stand to one another can be 

readily ascertained. In the case, however, of the much more 

complicated compounds of the organic branch of the science, 

this cannot be so readily done. Thus, for instance, in the case 

of caffeine we have : 

49-51 ^ , „ 
= 413 



12 
5-22 
1 
28-99 

14 

16-28 

16 



= 5-22 

= 207 
= 102. 



These numbers stand in the relation of 4, 5, 2, 1. As, how- 
ever, the sum of the monad atoms must be an even number, 
we are obliged to take as the simplest formula CgHj^jN^Og. 

If, according to the same plan, we calculate the formula of 
the volatile hydrocarbon whose analysis has been given in 
Example No. 1, we find that this is a paraffin, but which of the 
paraffins it is remains doubtful, for, as the following calcu- 
lated results show, this compound may be one of at least three ; 
inasmuch as the composition of each of these bodies does not 
differ from that of the other, more widely than the results of 
several analyses of one and the same substance are often found 
to do. 

Hezane. Heptane. Octane. 

Carbon . . 8372 84*0 84*21 

Hydrogen .1628 16*0 1579 



100-00 100-00 10000. 

Again, in other cases, analysis gives no assistance whatever in 
the determination of the formula. Thus, for instance, a very 
large number of different formultx3 may be found which will agree 
sufficiently well with the experimental results in the case of 
aurin (Example No. 2). Of these, we will here give only three : 

^l.']"-10^2- t^l9"l4^:i- ^*2->"^lS^4- 

Carbon . . 7879 78-02 7853 

Hydrogen 505 4*88 471 

Oxygen . . 1016 16*55 1676 

10000 10000 100-00. 

G 2 



84 DETERMINATION OF VAPOUR DENSITY. 



Molecular Formulcc, It is, however, not necessary merely to 
determine the simplest formula of a compound, but, if possible, 
its molecular formula, and this can readily be accomplished if 
we can determine its molecular weight. 

The only perfectly reliable method for this purpose, in cases 
in which the body can be volatilised without decomposition, is 
to ascertain its vapour density. Hence we now proceed to 
describe the various methods which have been employed for 
this purpose. 

DETERMINATION OF VAPOUR DENSITY. 

64 By the density or specific gravity of a gas or vapour is 
meant the weight of a given volume compared with the same 
volume of air taken as the unit. 

Two methods for determining vapour density were, until 
recently, in common use, and although they are neither of them 
now employed in organic chemistry, their description is still of 
interest from an historical point of view. 

The principle of the first method, which we owe to Gay- 
Lussac,^ consists in determining the volume of a given weight of 
vapour ; whilst that of the second method, proposed by Dumas,* 
consists in the determination of the weight of a given volume of 
vapour, and this process is still employed for determining the 
vapour density of difficultly volatile liquids. Although the first 
is the older of the two methods, the second or Dumas' method 
is the simpler, and it, therefore, will be first described. 

Duvuis' Method. A thin glass bulb or globe of from 200 to 
300 cbc. capacity, having its neck drawn out and bent as shown 
in Fig. 41, and filled with dry air, is carefully weighed, the 

temperature of the balance-case being ascer- 
tained. A quantity of the liquid under ex- 
amination, varying according to the capacity 
of the globe, is then introduced, such a 
quantity b?ing however always taken that the 
vapour evolved is sufficient in quantity to 
expel the whole of the air. The bulb con- 
taining the liquid is then heated in an iron 
P ^^ vessel which is filled, according to the vola- 

tility of the substance, either with water, oil, 
or paraffin (Fig. 42), the temperature being raised to a point 

* Biot, Traiti de Phys. i. 291. ' Ann, Chim. PJnja. (1827) xxxir. 326. 




DUMAS' METHOD. 85 

at least from 30° to 50° above the boiling-point of the liquid, 
the reason for thia precaution being that vapours obey the 
laws of gaseous expansion and pressure more exactly at tem- 
peratures considerably removed from their boiling-points than 
at lower temperature?. 

When no further vapour issues from the drawn-out point, aa 
may be seen by holding a flame in front of the opening, the 
capillary tube ia sealed as close as possible to the surface of the 
liquid. At the same time the temperature of the bath is read 
off by means of a thermometer placed in the heated liquid at a 



*'—' t 




height corresponding to the centre of the globe. The globe is 
next removed, carefully cleaned, and again weighed when cold, 
together with the drawn-off point. It is then only necessary to 
detenoine the volume of the globe. For this purpose the sea!ed 
end ia broken under mercury, and, if the experiment has been 
snccesafiilly carried out, the whole of the bulb will be filled by 
the mercury with the exception of the small volume occupied by 
the condensed hquid, and this volume is usually so small that 
it may be disregarded. If, however, it is desired to determine 
this amount, the condensed liquid is allowed to pass into the 
narrow neck of the bulb, nrtl this then replaced by mercury. In 



86 DETERMINATION OF VAPOUR DENSITY. 



case the whole of the air has not been completely removed by 
the vapour, a bubble of air remains, and its volume may be 
ascertained by passing it into a graduated tube over mercury. 
To determine the volume of the mercury contained in the globe, 
it is poured into a carefully graduated cylinder or else weighed. 
This weight in grams divided by 13*59 gives the volume of the 
mercuiy in cubic centimeters. The calculation is simple, especi- 
ally if no residual air occurs, and this may be readily avoided by 
taking enough substance. The following are the experimental 
data: 

Weight of the globe with air at f — g. 

„ „ vapour at .7^ = G, 

Capacity of globe . . = C 

The weight of the vacuous globe is found from the following 
formula, inasmuch as 1 cbc. of air at 0° and 7G0° weighs 
0*001293 grm. The height of the barometer may, in this case, 
be neglected, as the variation is very slight during the progress 
of the experiment. The weight of the air contained in the 
globe is : 

Cx 0001293 



- — j\ 



1 + 0003665 x^ 

The vacuous globe will, therefore, weigh y — x, and that of the 
vapour G — (jj ^x)=y. We have now to find what an equal 
volume of air at the same temperature weighs. We have thus 
the equation : 

( 7x0 001293 _ 
1 4-0 003665 X T"^' 

The vapour density (D) is therefore : 

The calculation is considerably simplified if we make use of a 
table showing the weight of 1 cbc.- of air at different tempera- 
tures. The following table is sufficiently accurate for ordinary 
use. This table may be also employed in the calculation of 
vapour density according to otlier methods. It gives the value 
for every 10**; the intermediate values can easily be obtained 
by interpolation. 



EXAMPLE OF DUMAS' METHOD. 



87 



t'. n. 


t . 


n. 


. . OOO1203 


170 . . 


0000796 


10 . 




0001243 


180 . . 


0000779 


20 . 




0-001205 


190 . . 


00007G2 


30 . 




. 0-001165 


200 . . 


0-000746 


40 




. 0-001128 


210 . 


0000730 


50 




. 0001093 


220 . 


0000715 


60 




. 0-001060 


230 . . 


0-000701 


70 




. 0001029 


240 . 


0000688 


80 




. 0001000 


250 . 


0000674 


90 




. 0-000972 


260 . , 


. 0000662 


100 




. 0-000946 


270 . 


0000650 


110 




. 0000921 


280 . 


. 0*000638 


120 




. 0000898 


290 . 


. 0000626 


130 




. 0000876 


300 . 


0000616 


140 




. 000854 


310 . 


. 0-000605 


150 




0-000834 


320 . 


. 0000595 


ICO 




. 0000815 






TLe following formula may b 


e used with this 


I table : 






T. G- 


■n+f'ni 





^" CnT ' 

TLe following example serves to show the limits of error 
accompanying the determination of vapour density by this 
method. 

Example of Dumas Method, A volatile hydrocarbon (hexane, 
CgHjJ of the paraffin series, of which the analysis has been 
given, yielded the following results: 



e = 

G = 

c = 



23-449 

15^^-5 

23-720 

lur 

17S cbc. 



The density calculated from these numbers is 2'986, whilst 
that required by the formula is 2' 979. 

65 Gaij'Lu^sac s Method, In this process the graduated and 
calibrated glass tube G (Fig. 43) is employed, filled with mercury, 
and placed in an iron vessel containing this metal. The sub- 
stance is contained in a very thin bulb or small stoppered tube 
of known weight (Fig. 44); this is then filled with the liquid, 
again weighed, and then passed up to the top of the divided 
tube. Surrounding this is a wide glass cylinder open at both 



B» 



DETEBMINATION OF VAPOUR DENSITY. 



ends and filled with water. The iron vessel is now heated by gaa 
or charcoal. The expansion due to the heat either causes the 
bulb to burst or drives the stopper out of the tube, and the 
liquid is soon thus completely converted into vapour. To effect 
an equal distribution of temperature the water is continually 
stirred. Aa soon as the temperature at which the determina- 
tion has to be made is reached, the volume of the vapour, the 
temperature of the water, and the height of the barometer are 
read off; whilst, at the same time, the temperature of the air 
and the difference between the height of the mercuiy inside and 
outside the tube are ascertained. 




^ 



£j.iimplc of Gttij-Zussaes Method. A determination of the 
vapour density of pentane, CjUjj, made by this method, gave the 
following results : 

Weight of pentane ... 0101 



Tompernturo of air 
Temperature of vapuui 
Volume of vapour 
Height of baroiiit^tcr 
Difference of level . 



16' 

or 

50 '5 cbc. 
752 mm. 
tlQ mm. 



GAY-LUSSAC'S METHOD. 89 



The pressure inside the tube was consequently equal to that 
of a column of mercury of 752° mm. at 1G° minus that of 
a column of 220"* mm. at 91''. In order to be able to substract 
one from the other, these values must first bo reduced to the 
same temperature. As the co-efficient of expansion of mercury 
for 1** is 0-00018, the heights at 0° will be : 

^''- = 749-9 



^^^ - =21G'4. 



1 + (0-00018 X 16) 

220 
1 + (O-OOOiS X 9!) 

The pressure inside the graduated tube was therefore : 

749-9 -21G-4- 5:33-5. 

59*5 cbc. of pentane weigh, at 91° and under a pressure of 
533*5 mm. of mercury, 0*101 gram. Under the same conditions 
an equal volume of air weighs : 

0001293x59-5x533-5 ^Q.Q4g3 
760xl + (0"003665x91) 

Hence the vapour density of pentane is : 

^•\^\ = 2-493, 
U-0405 

and this agrees well with the theoretical value 2494. 

Gay-Lussac's method possesses the great advantages of requir- 
ing very small quantities of the substance, and of enabling several 
determinations to be made at any temperature under 100°. On 
the other hand, it is not well adapted to the case of substances 
possessing high boiling-points, inasmuch as the cylinder must 
then be filled with oil or paraffin, and a constant temperature 
of the column cannot in this case be easily attained. Poisonous 
mercurial vapours are also given oflf during the process, and 
this renders the method dangerous in the case of bodies re- 
quiring high temperatures. In order to overcome this objection, 
Natanson has constructed an air-bath iu which only the upper 
part of the tube is heated, but this modification has not come 
into general use. 

66 Hofmanns Method. Hofmann ^ conceived the happy idea 
of employing a wide barometer-tube in place of the short tube 
used by Gay-Lussac, and of heating this by the vapour of a 

' Bcr, DeuUch. Chim, Ocs. i. 198. 



90 DETERMINATION OF VAPOUR DENSITY. 

liquid boiling at a, coDstant tciuperaturG. The apparatus ia 
shown in Fig. 45. The graduated barometer-tube (a), more 
than 1 meter in length, is filled with dry mercury and placed in 
a mercurial trough. Outside this a wide glass tube (b) is placed, 
closed at its upper end by a well-fitting cork, through which 




Fio. *fi. 



the tube d jiivascs fur the entrance of the heated vapour. The 
condensed liijuid and the excess of vapour piss away through 
the tube e into the condenser (y). A very small stoppered 
bottle whose weight is known, having a capacity of from OO-') 
to Olcbc. (Fig. 46). is filled with a known weiglit of the sub- 
stnuce. The bottle thus filled is passed up to the top of thi> 



HOFMANN'S METHOD. 



91 




mercury in the barometer, and in the case of the more volatile 
liquids this usually displaces the stopper at once, and in other 
caaes it is easily driven out when the substance becomes heated. 
The copper vessel (/) serves to contain the liquid of constant 
boiling-point, and by this means the barometer-tube is easily 
brought up to a constant temperature. As soon as the 
meniscus of the mercury is seen to remain unchanged, 
ike volume of the vapour and the height of the mer- 
curial volume are read off by means of a pendulum 
cathetometer (i). In many cases water may bo cm- 
ployed as the heating liquid, inasmuch as the vaporisa- Fio. 46. 
tion of the substance takes place under diminished 
pressure, and bodies which boil up to 180° can be completely 
volatilised at 100°.i 

For the purpose of determining the vapour density at higher 
temperatures, Hofmann makes use of the following substances : 

noiling-point. 

Aniline 181° 5 

Toluidine 202 

Ethyl benzoate . . . . 212 

Amyl benzoate .... 261. 

Of course other bodies may be employed provided their boiling- 
points do not lie too near that of mercury. 

The calculation is carried out in a similar way as in Gay- 
Lussac's method, but inasmuch as the lower portion of the 
mercurial column is not surrounded by vapour, two calculations 
are necessary in order to reduce the height of this column to 0^ 
In addition to this, the tension of the vapour of mercury must also 
be taken into account when high temperatures are necessary. 
For this purpose the well-known table of Regnault ^ is employed, 
the following extract from which is sufficient for most purposes > 



Temperature. 


Tension of 
Vapour. 

5 9 mm. 


1 

Temperature. 

220° 


Tension of 
Va|)0ur. 

1 


160' 


1 

;34-7U mm. ! 


170 


8-09 


230 


45 -35 


180 


11-00 


240 


58-82 


190 


14-84. 


250 


75-75 


200 


19-00 


1 260 


96-73 


210 


2G-n5 ! 


270 


12301 



* Schroder, Ber, Deutsch. Cliem. Gcs. iv. 472. 



Phil. Hag [4] xx. 227. 



92 DETERMINATION OF VAPOUR DENSITY. 



67 Another great improvement suggested by Hofmann^ is that 
of using a plain tube instead of a graduated and calibrated one. 
Not only are these plain tubes cheaper than the calibrated ones, 
but they are also much less liable to fracture, inasmuch as all 
glass tubes in which divisions have been etched are liable to 
crack when exposed to rapid changes of temperature. For 
this purpose, a tube as cylindrical as possible is chosen, and 
when the mercurial column has become stationary, the pendu- 
lum cathetometer is placed in position. The apparatus is then 
allowed to cool, and, after removing the outer glass tube, a 
slip of paper is placed at the point where the meniscus stood. 
After the volume of the vapour has been thus determined, the 
tube is dismounted and filled with mercury up to the mark, and 
then the mercury weighed on a pair of common scales capable of 
turning with half a grain. From the weight of the mercury 
the volume of gas in cubic centimeters is obtained. 

In the apparatus above described, two calculations, as we have 
seen, are necessary in order to obtain the height of the mercury 
at 0^ This, however, does not give a strictly correct result, 
inasmuch as the column of mercury which is not surrounded by 
vapour does not possess the same temperature throughout its 
length. Tlie temperature of that portion near the cork is 
necessarily higher than that of the air. In cases where the 
temperature is not high this difference is of little moment, but 
at a high temperature it may become of consequence. In order 
to avoid this error, Wichelhaus* has proposed to substitute 
Hofmann's barometer-tube by a syphon barometer. The ap- 
paratus, however, thus becomes much more complicated and 
liable to fracture; moreover, the height of the outside tube 
requires to be greater, and this necessitates the employment of a 
larger quantity of vapour in order to obtain a constant tempera- 
ture. Another disadvantage involved in the employment of a 
syphon barometer is that only one experiment can be made 
with the same material, for when the tube cools, air enters into 
the vacuous space. By the use of a straight tube, on the other 
hand, the volume of the vapour may not only be redetermined 
at the same temperature, but its volume at different temperatures 
may be ascertaine<l. 

Hofmann has, therefore, improved his apparatus by allowing 
the outer tube to dip into the reservoir of mercury at the bottom, 
A small tube being sealed on at a distance of from 2 to 3 mm. 

> Btr. DeuUth. Chcm, Oes. ix. 1^04. « £cr, DcuUch, Chim, Gca. iii. 106. 



HOFMANN'S METHOD. 93 



from the surface of the mercury, hy means of which the excess 
of vapour and products of condensation can be withdrawn. 

Lastly he obtained the same result in a still simpler manner. 
The barometer-tube stands upon a thick plate of caoutchouc lying 
at the bottom of the mercurial trough, and this plate is fastened 
to an iron disc furnished with a handle which is bent so as to 
come out of the mercury. In one side of this plate a groove is cut 
by means of which the mercury in the tube is brought in contact 
with that in the trough. When the vapour passes through the 
outer tube, which only needs to be 40 cm. longer than the 
barometrical column, the mercury which it contains flows out 
into the trough, and as soon as the volume of the vapour has 
become constant, the caoutchouc plate is pushed back so that 
the mouth of the tube is closed, and thus the mercury in the 
tube is separated completely from that in the trough. This is 
done by means of the handle, so that the level of the mercury 
remains unaltered. As soon as the cathetomcter has been placed 
in position, the whole is allowed to cool, and the height of 
the mercury is determined at the temperature of the air, the 
calculation being then carried out as alrea<ly described. 

Further modifications of the apparatus have been made by 
J. W. Briihl ^ and C. Engler.^ 

As the substances employed for the preparation of vapour at 
higher temperatures than the boiling-point of aniline are costly, 
it became advisable to use as small a quantity of these as 
possible. This is arranged for by Hofmann,^ inasmuch as the con- 
densed liquid is allowed to run back again into the boiler. By 
means of such an arrangement a constant temperature can be 
attained in from twenty to twenty-five minutes and maintained 
for several hours, with a volume of from 100 to 150 cbc. of liquid. 

As an example of the calculation in Hofmann's method we 
may take the vapour density determination of ethyl-propinyl 
ether, C^HgO : 

Weight of substance, 00518 - S, 
Volume of the vapour, 525 cbc. =v. 
Temperature of the vapour, 100° = 7. 
Temperature of the air, 15° = ^. 
Height of barometer, 752°'5 mm. = ff. 
Height of mercurial column, 484 mm. = A. 
Reduced pressure, 275 mm. = h\ 

1 Bcr. DeutscK Chr.m, Ges. ix. 136S ; xii. 197. » Jhid. ix. 1419. 

* Ber, Deutxh, Chcm. Get. 1876, ii. 1304. Chcm. Soc, Jonm, 1877, i. 33. 



94 DETERMINATION OF VAPOUR DENSITY. 



Hence the vapour density is obtained by the following 
formula : 

_ /g X 760 X (273 -f T ) 
0-001293 X 273 X v x cT ^' 

Found. Calcuktetl. 

2-895 2-909. 

Hofmann's method soon almost entirely superseded the two 
older methods, Dumas' being employed only for the determination 
of the vapour density of substances which have a high boiling- 
point, and for this purpose improvements were made in the 
method by Troost and Deville,^ as well as by Bunsen.* Dumas' 
method is also subject to the serious disadvantage, that the 
greater portion of the material employed, frequently more than 
3 grams, is lost during the operation, and this, in the case 
of expensive preparations, is a matter of serious inconveni- 
ence. In order to overcome this diflBculty, various suggestions 
have been made, by means of which the escaping vapours could 
be caught and condensed, but this leads to complications which 
destroy the simplicity of the method. 

Habermann * has lately made another suggestion. He con- 
nects the fine neck of the globe with a Bunsen filter-pump in 
order to* produce a vacuum, whereby the substance, as in 
Hofmann's method, boils at a lower temperature. By this 
method not less than 1 gram of the substance must be em- 
ployed, and this can readily be condensed in a bulb-tube placed 
between the globe and the pump. By this means, however, 
Habermann has only been able to determine the vapour density 
of such substances as boil below 250°. 

68 Victor Meyer's Methods, Method No, 1. Victor Meyer * has 
recently worked out a plan by means of which, without cm- 
ploying a greater quantity of the substance than that used 
in Gay-Lussac's or Hofmann's process, the vapour density of 
high boiling bodies may be determined at a temperature of 
448^ the boiling-point of sulphur. He employs Wood's fusible 
metal as the liquid over which to collect the gas, and makes use 
of the bulb-tube shown in Fig. 47. In carrying out the ex- 
periment, about 50 mgrm. of the substance are allowed to 

» Ann. Chim, Phys. [3] Iviii. 257. 

• Ann, Chem. Pharm, cxli. 273. 
' Lie bigs Anna! en ^ clxxxrii. 341. 

* Jkr, Dcut9ch, Chem. Oca, niQ, ii. 1216. 



VICTOR MEYER'S METHODS. 'J5 

vaporise in a vessel completely filled with the liquid alloy, the 
vdume of vapour being ascertained from the weight of the 
metal which flows out.^ A substance which is solid at the 
ordinary temperature is weighed out iu a short glass tube 
sealed up at one end, Fig. 48 (a), whilst liquids are enclosed in 
small stoppered bottles, which differ from those used by Hofmanu 




Fio. 47. Fio. 48 (S). 

by being slightly curved in order that they may more readily 
pass up into the bulb-tubo. Fig. 48 (b). The whole apparatus is 
then heated to 100°, and afterwards placed on a laiige balance 
and weighed to within a decigram. 

The apparatus must then be heated iu the vapour of sulphur. 
This ia accomplished in a cast-iron crucible of 400 chc. capacity, 
which is loosely covered (Fig. 49). The crucible contains from 1 20 
to 130 grams of sulphur, and is heated by means of a powerful 
burner. After about twenty minutea, when the sulphur is 
boiling rapidly and the current of vapour passes out between the 
cover and the crucible, the boiling is allowed to go on for about 
four minutes, the burner then turned out and tho huib-tube 
lifte<l out of the crucible. The vapour contained in the bulb 
at the moment the bulb Js withdrawn from tho crucible Ja 
under the prosssure of the atmosphere plus that of the short 
column of fusible metal in the bent tube. The height of the 
column has therefore to be ascertained. For this purpose a 
finely drawn-out glass tube, having a drop of seaUng wax at the 



' Similar methods for lower temjM'rnturca, by mnking lue of mercuTy, had brcn 
fonnftrly snggrated ; Hofmann, Ann. Chern. Pharm. Suppl. i. 10 ; Werthfim, 
ibid. cxKiii. 173 ; cxzviL Bl ; ckxx. 269 ; \V. UarshninVatts, Laboratonj, l. 2S5. 



96 DETERMINATION OP VAPOUR DENSITY. 

end, ia brought oq to the glass at the height of the meniacus in 
the iiiDer tube. This leaves a mark by means of which the 
height can be ascertained. For the special precautions which 
the author recommends, the original paper must be referred to. 




The following furmula senses for the calculation : ' 

.S>^ 760( 1 +0-0O3MS y. tU-J^ _ ^__ 

0001293 [Pt-^p]r('_"— + -'-)(l + 84(|-2x 0-0000803)- -I_l 
' ""LV»908 130/ ' »16»J 

By collecting the constants, we obtain the equation : 



/> r 

[/•+3 7']| 



-. Dtutseh. Cktm. Ott. x. S07D. 



VICTOB MEYER'S METHODa 



In these formula; : 

5= Weight of the substance. 
P = Height of barometer reduced to 0°. 
p = Pressure of column of metal, which is two- 
thirds that of mercury, 
et= Weight of alloy employed. 
9-608 = Specific gravity of alloy at 100°. 
9 158 = Ditto at 448°. 

q = Weight of mercury contained in small bottle. 
r = Weight of the remaining alloy. 

As the tube containing the substance ia very small, q may 
be neglected. 

The vapour density of methyl-anthracene, a 
body boiling at a higher point than mercury, was m 
thus ascertained : 



S " 0-0360. 




a = 283-33. 




r = 168-9 




P = 722-3 mm. 




p = 34-0 mm. 




Foil 11 J. 


Calciilitted 


Vapour density , . 6-J7 


6-63. 




69 Method No. 2. In order to determine the 
vapour density of bodies boiling below a tempera 
ture of 3.)0°, V. Meyer' has proposed a method 
by means of which the molecular weight may be 
determined with great simplicity and ease. The \ 
vessel in which the substance is placed is filled 
with mercury, as shown in Fig. 50. It is niiide 
of thin glass, and hiis a capacity of 35 cbc. This 
is filled according to the method already described, but at 
the onlinary temperature, at which it is weighed. It n 
then hung by a thin wire in the boiling flask {Fig. 51), the 
neck of which being lung does not require any condensing 
arrangement, and it is then heatcil to the boiling-point of 
water, aniline, or any other higher boiling liquid. When no 
more mercury is seen to ilow out, the apparatus is removed and 

' BtT. DtulKh. Cht!,,. Cm. 1877, IL 2008, 



DETERMINATION OF VAPOUR DEN3ITY. 



after cooling weigLed again. In order to determine the excess 
of pressure in the side-tube, the capillary tube is opened, an<1 




the wl.i.l.' is tillrd 1 
wid.T tnhr. 



iry, and tlio point markoi 



VICTOR MEYER'S METHODS. 99 



In the calculation the following data are required : 

S = Weight of substance. 

T = Temperature of vapour. 

^ = >, n air. 

P= Barometric pressure reduced to 0^ 

p « Excess of pressure in the side-tube. 

8 = Tension of mercury vapour. 

a = Weight of mercury employed. 

r = Weight of remaining mercury. 

q = Weight of mercury contained in the small bottle. 

The last number is required only in very exact determinations. 
The calculation is effected by the following formula : 

_ 5 X 760 (1 -t- 036657) 1 3-59 _ ^ 

""(^ +!» - «, 0-U0liy3\o+y; ^l + (HM)0303 [T - <]) - r) (1 -f 0"00UlO [T - tjj (fx 00001b)* 

13 '59 is the specific gravity of mercury at 0°. 
0*0000303 is the coefficient of expansion of glass. 
O'OOOIS ditto of mercury, which above 240° rises to 
0-00019. 

The constants in the above formula are : 

760x13-5 9 
001293 -'^»^0^^- 

The temperature of the vapour does not need to be deter- 
mined, as the boiling-point of the liquid employed is known. 
In the case, however, of bodies whose boiling-points approach 
tliat of mercury, it is necessary to determine the temperature, as, 
according to the recent experiments of Naumann, it appears 
that the boiling-points of liquids which are not miscible undergo 
considerable depression. Thus he finds that diphenylamine, 
which boils at a temperature of 31 0** by itself, boils at 290"* 
when mixed with mercury. 

The vapour density of benzoic acid was in this way deter- 
mined in the vapour of diphenylamine with the following 
results : 



/S= 00603. 


ji> = 21 mm. 


a = 471*7 grams. 


r-290°. 


r = 66*4 grams. 


t =15°-2. 


q -= 1 gram. 


.s = 165*7 mm. 


P= 726 mm. 






Found. (.'alculated 


Vapour density . . . 


. . 4-20 4-22. 


• 


n 2 




100 



DETERMINATION OF VAPOUR DENSITY. 



70 Method No, 3. Victor and Carl Meyer^ have recently 
described an easy method for determining the vapour density of 
bodies of low, as well as those possessing a very high, boiUng-point. 



10 





Fio. 52. 



Fig. 53. 



This is especially valuable for bodies boiling above 448", and for 
such as attack mercury or fusible metal. The temperature to 



> lUr. nnifjurh, Chfm. f.Vjr. 187S ii. 22r.r?. 



VICTOR AND CARL MEYER'S METHODS. 101 



which the vapour is heated does not require to be determined, nor 
is it necessary to know the volume of vapour at that tempera- 
ture, as both of these values are eliminated in the expression 
for the density. The only observation which is required is the 
volume of the vapour in the form of its equal volume of air 
measured at the atmospheric temperature. The apparatus is 
shown in Fig. 52. It consists of the boiling flask c, in which is 
placed the glass 6, having a capacity of about 100 cbc.; and on 
to this is fused a tube 600 mm. in length, closed with a caoutchouc 
stopper (d), and furnished with a short capillary gas-delivery 
tube (a). The substance employed for heating purposes may 
be any of those already mentioned. 

If it be necessary to work at a temperature above 310**, a bath 
of molten lead (Fig. 53) is employed, which can be heated to a 
temperature sufiSciently high for the complete volatilisation of 
the substance. This point is easily ascertained by dipping a 
thin tube containing a small quantity of the body into the lead 
and seeing whether it boils quickly. The experiment is com- 
menced by heating the empty vessel h (at the bottom of which 
a small plug is contained) in the long tube or in the lead bath. 
The tube is closed by the stopper d, and the gas-delivery tube 
dips in the water of the trough. As soon as the temperature 
becomes constant, and when, therefore, no further evolution of 
air is observed, the stopper is quickly removed, and a weighed 
quantity of the substance (such in amount that its vapour does 
not occupy more than half the volume of the vessel b) thrown 
in and the cork quickly replaced, the graduated cylinder filled 
with water having been placed over the end of the gas-delivery 
tube. The substance at once evaporates, and in fifteen seconds 
displaces its own volume of air which collects in the cylinder. 
As soon as no further bubbles are emitted, the tube is removed 
into a larger cylinder filled with water, the levels of the liquids 
brought to the same point, and after a time the volume of the 
air read oflF, the temperature of the water and the height of the 
barometer being at the same time observed. These observations 
yield sufiScient data for the calculation : 

^= Weight of substance. 

t = Temperature of the water. 

i^ = Barometric pressure reduced to 0'. 

iv = Tension of vapour of waters 

V~ Volume of air. 



102 DETERMINATION OF VAPOUR DENSITY. 



The vapour density is calculated by the formula : 

Sx760 ( 1 + 00036650 
~{B-'W) rx 001293' 

or, by collecting the constants: 

S (1 + 00036650 X 587780 

As examples we may quote the following : 

(1) Chloroform, CHCI3, in water vapour. 

S- 01008 ^ = 16'-5 J?= 707-5 mm. r=22cbc. 

Calculated. Foand. 

Vapour density . . 4*13 41 3. 

(2) Benzoic acid, C^H^Og, in diphenylamine vapour. 

5=0 0855 /=16" J5= 717-8 mm. r=17'8cbc. 

Calculated. Found. 

Vapour density . . 422 424. 

(3) Diphenylamine, CjgHjjN, in lead bath. 

S = 00905 ^ - 17' i? = 714-8 mm. r= 136 cbc. 

Calculated. Found. 

Vapour density , . . o\i3 5*92. 

The same experimenters have employed this method for the 
determination of the vapour density of inorganic compounds 
which volatilise at a red-heat or even at a higher temperature. 
For this purpose the glass vessel is replaced by one of porcelain 
or platinum heated in a suitable gas-furnace.^ 

The literature of the subject must be referred to for 
further information respecting the subject of vapour density 
determination.^ 



1 Ber. Dtutsck, Chem. Ges. 1879, 1112. 

' Gnbowski, Ann. Chem, Pharm, cxxxviii. 174 ; Landolt, Ber. Dcutseh. Chem, 
Oet. Y. 497 ; Goldschmidt and Ciamieian, ibul, x. 641 : Uofmann, ilnd. ix. 962 ; 
zi. 1884 ; Pfaundler, ibid, xii. 165. 



MOLECULAR FORMULAE OF VOLATILE BODIES. 103 



DETERMINATION OF MOLECULAR FORMULA. 

71 (a) Molecular Formulce of Volatile Bodies, — When the per- 
centage composition and the vapour density of a compound are 
known, the molecular formula can bo readily ascertained. 
Hydrogen is 14'43o times lighter than air, and hence the 
molecular weight of a substance is obtained by multiplying 
its vapour density by twice 14*435. 

Eocample No. 1. Thus, for instance, the molecular weight of 
the above-mentioned paraflBn is 2*986 x 2887 = 802, or in round 
numbers 86. Now, as the percentage composition of this body 
is known, the amount of carbon and hydrogen contained in 
86 parts can be readily found. 

83*87 X 86 ^o - ^ , 
— — ■ — =- /213 carbon. 

^^'--^ ^ ^^ = 13-97 hydrogen. 

100 ^ ^ 

If we divide the numbers thus obtained by the atomic 
weights, we 'find that the hydrocarbon is hexaue, C^H^^. The 
want of exact afinreement between the numbers thus obtained 
and those calculated from the formula is explained by the fact 
that the above numbers contain the experimental errors due 
both to the analysis and to the vapour density determination. 
This error may be partially eliminated if we compare the 
theoretical composition and vapour density, directly with the 
numbers found by experiment : 





Found. 


Culculated. 


Carbon . . . 


. . 83-87 


83-72 


Hydrogen . . 


. . 16-25 


16-28 



100*12 100-00 

Vapour density . . 2986 2*979. 

The numbers thus found are seen to agree well with the 
calculated values. 

Example No. 2. Methyl-anthracene gave on analysis the 
following percentage composition : 

Carbon 9392 

Hydrogen 623 

100*15. 




104 DETERMINATION OF MOLECULAR FORMULA. 

Its vapour density is G'57, and hence its molecular weight 
is 100, and the amount of carbon and hvdrogen contained in 
190 parts is: 

Carbon 178*5 

Hydrogen 11*8. 

These numbers, divided by the approximate atomic weights, 
give: 

^'^'^ = 14-9 
12 ^*"'' 

showing that methyl anthracene possesses the formula C^jH^g. 
This corresponds to a theoretical vapour density of 6*63, and 
a percentage composition of: 

Carbon 93-75 

Hydrogen 625 

10000. 

Example No. 3. As a last example of this kind we may take 
ethyl propenyl ether, whose vapour density determination has 
been already given. Ultimate analysis gave : 

Carbon 7126 

Hydrogen 9*55 

Oxygon 1919 

locFoo. 

Its molecular weight is 28*87 x 2-895 = 83G. 

83 6x71-26 .^^^ ^ 
, . — — i>9'60 carbon. 

83-6 X 9-55 ^ ,,^ , , 

lUO " "" / ••)8 hydrogen. 

83-6 X 1919 

UK) " =1^^"^^ oxygon. 

Hence the molecular formula is C-H^jO, and this corresponds 
to : 

C. 60 71-43 
Hg 8 9-53 

O 16 1904 

lOOUO. 



MOLECULAR FORMULA OF ACIDS. 105 



7a (b) Molecular Farmulce of Acids. Many carbon compounds 
are acids whose molecular weight, whether they be volatile 
or not^ may be readily ascertained by determining in the first 
place whether the acid is monobasic or polybasic, and then 
analysing one of its salts. As a rule the silver salts are 
employed for this purpose because they are easily obtained 
anhydrous and in the pure state, and because they leave a 
residue of pure silver on ignition. 

Example No, 4. The composition of monobasic melissic acid, 
according to analysis, is as follows : 

Carbon 79-61 

Hydrogen 13*48 

Oxygen - 6*91 

100-00. 

Ignition of the silver salt showed that it contained 19*3 per 
cent of silver. Hence the molecular weight of this salt is : 

100 X 107-7 __ 
i9-3 -"^^ • 

This salt differs from the acid by containing one atom of 
silver in place of one atom of hydrogen. Hence the molecular 
weight of the acid is : 

(558-107-7)+ 1=451-3, 

or the even number 452 may be taken as representing the 
molecular weight of the acid. The weight of carbon, hydrogen, 
and oxygen contained in the molecule will then be respectively : 

luo -•^•>'^ 

13:48 x^52_ 

100 ~ ^^'^ 
6 91 X 452 

100 ~ ^^ "• 

Hence the formula is CsoHg^Oj, and this gives : 

C30 360 79-64 

H^ 60 13-28 

Oj 32 708 

452 100-00. 



106 DETERMINATION OF MOLECULAR FORMULA. 



The calculated percentage of silver, namely, 19*28, in the 
above salt, agrees with that which has already been described. 

EocamplcNo, 5. Analysis of silver benzoate gave the following 
results : 

Carbon 36 68 

Hydrogen 210 

Silver 47*16 

Oxygen 13-97 

100^00. 

Benzoic acid is likewise monobasic^ and the molecular weight 
of its silver salt as calculated, as in the last example, is 228*4, 
that of the acid being 120*7. If the quantities of the various 
elements contained in 228*4 parts of the salt be next calculated, 
the formula CyH^AgOj is obtained. Hence the acid is C^H^Og, 
as is shown by the following comparison of the theoretical with 
the analytical results : 

Calculated. Found. 

Cy 84 36*73 36*68 

H^ 5 2*19 219 

Ag 107*7 47*09 47*16 

O, 32 1399 13*97 

100*00 100*00. 

Example Xo. 6. Meconic acid, a compound found in opium, 
is a polybasic acid. On adding silver nitrate to its aqueous 
solution, a white silver salt is precipitated, but when the same 
reagent is added to a solution of the acid previously neutralised 
by ammonia, a yellow silver salt is obtained. The composition 
of the acid and of the two silver salts is found by experiment 
to l>e : 

Meconic White Silver Yellow Silver 

Acid. Salt. Salt. 

Carbon . . . 420 20*2 15*9 

Hydrogen . . 20 0*5 0*2 

Oxygen . . . 56*0 270 21*9 

Silver . . . ~ .52*3 62*0 

lOlTo 100^0 100*0. 

If in the first analysis the numbers be divided respectively 
by the atomic weights of the elements, we obtain the following 



MOLECULAR FORMULAE OF ACIDS. lOT 



relation between the number of atoms of the constituents of 
the acid : 

42 



12 ~ 


3-5, 


2 
1~ 


2-0, 


56 
16 ~ 


3-5. 



The most simple formula of meconic acid deduced from these 
numbers is CyH^O^, but whether this, or a multiple of it, ex- 
presses the molecular weight cannot be decided by the results 
of analysis. In the two salts different quantities of hydrogen 
are replaced by silver. The white salt contains for every seven 
atoms of carbon : 

0*5 X 84 

— o7y:«~~ = ^'^ parts, or 2 atoms of hydrogen, 

— c^^^^ = 217*0 parts, or 2 atoms of silver. 
20*2 ^ 

In the yellow salt we find : 

- , .-.^- = r05 part, or 1 atom of hydrogen, 

62*0 X 84 

■ "^ , r.(> " = 327*5 parts, or 3 atoms of silver. 

From this we conclude that the acid is tribasic, and that the 
formula C^H^Oy represents a molecule. A further confirmation 
of this conclusion is found in the fact that acid salts containing 
only one atom of a monad metal are known. 

The molecular formulae of the above compounds are 
therefore : 

Meconic acid C-.H^07, 

White salt , . . C^HgAggO^, 
Yellow salt . . . ilUAgfi.. 

In certain instances, an acid, whose molecular formula has 
to be determined, may be known to belong to a given 
homologous series. In this case, in order to determine its 
molecular formula, we only need to determine the quantity 
of silver, or of any other metal, contained in one of its salts. 



10« DETERMINATION OF MOLECULAR FORMUL-^l 



Example No. 7. An acid, which from its derivation and 
chemical relations undoubtedly belongs to the group of fatty 
acids, gives a silver-salt which yields, on ignition, 45 'ol per 
cent, of metaL Hence the molecular weight of the acid is 
130. The general formula, however, of the fatty acid series 
is CnH2n02 and the value of n is ascertained by the equation : 

14 M + 32 = 130 
.'. n = 7. 

Hence the molecular formula of the acid is CjH^fi^. 

73 (c) Molecular Formvice of Bases. Many carbon compounds 
exist which contain nitrogen, and which act as bases, combining 
like ammonia with acids. Some of these bases are monacid, 
others are polyacid. In order to find the molecular weight 
of such a compound, it is only necessary to ascertain the 
quantity of acid contained in an anhydrous normal salt, or, 
better still, to find the quantity of platinum present in the 
double salt formed by the combination of the hydrochloride 
with platinic chloride, and which, like ammonium platinic 
chloride, contains two molecules of hydrochloric acid to each 
molecule of platinic chloride. 

Example No, 8. Caflfeine is a monacid base; its platinum 
double salt contains two molecules of caffeine and two molecules 
of hydrochloric acid combined with one molecule of platinic 
chloride, and 100 parts of this compound leave, on ignition, 
24*6 per cent, of platinum. Consequently the amount of the 
platinum salt which contains one atom, or 196*7 parts of 
platinum, is : 

196-7 X 100 _ 

24-6 "" ' ^^'^• 

The molecular weight of cafi'eine is found from this by the 
equation : 

2 71 + (2 X 36-5) -h 338-3 = 7996 
.*. n= 194. 

As the percentage composition of this base is known, its 
molecular formula can easily be found : 

194 X 49-51 ^^ , ^ ^ 
100 ^ carbon, 



MOLECULAR FORMULA OF BASES. 109 



194.x 5-22 _, ,, , 

100 =10*1 «f hydrogen, 

104.x 28-99 .^^ , . 

Yq.t — = oo'z of nitrogen, 

104 X 16-28 



lOU 



=* 31-58 of oxygen. 



One molecule of caffeine, therefore, consists of: 

96-1 ^ , , 

-y^ — 8-0 atoms of carbon, 

101 

- :j =10-1 atoms of hydrogen. 

56-2 

- -T- = 40 atoms of nitrogen, 

31-58 

— - — = 1-97 atom of oxygen. 

Its molecular formula is therefore Cj^H^jN^Og, corresponding 
to a molecular weight of 194, or more exactly of 193 78. 

In the determination of the molecular weiirht of an organic 
base we also often know beforehand to which homologous series 
it belongs. In such a case, the determination of the platinum 
in the double salt is sufficient to determine the formula. 

Examflc Ko, 9. A compound ammonia, having the general 
formula CnHQu-i-sN forms a double salt, 100 parts of which, 
on ignition, leave a residue of 33*02 of platinum. 

As the platinum double salt possesses the formula 
(C*nH.-»n + 3N,C1H)2 + PtCU, tlie molecular weight of the base is 
easily found to be 80, and hence we have the equation : 

12/1+271 + 3 + 14 = 80 
.-. n = 4-93. 

Hence the base possesses the formula C^HjgN, and has a 
molecular weight of 80 '86. 

74 (d) Molecular Formula' of Non-volatile and Neutral Bodies, 
Most carbon compounds, however, neither act as acids nor n.s 
bases, and if they are not volatile without decomposition, and 
do not enter into combination to form distinct compounds with 
other elements by means of which the molecular weight can 
be ascertained, the molecular formulae can be ascertained, in- 
many cases at least, by a careful examination of their chemical 
metamorphoses. 



no DETERMINATION OF MOLECULAR FORMULAE. 



Example Ko, 10. Numerous analyses of cane-sugar have 
shown it to possess the following percentage composition : 

Carbon 4210 

Hydrogen .... 6*44 
Oxygen 51*46 

lOO^O. 

As in the case of aurin, this result may be expressed by a 
number of diflferent formulae. In order to obtain a clue as to 
which of these is the correct one, we must consider certain 
general properties of the body. In the first place, cane-sugar 
when boiled with sulphuric acid is convei'ted into equal quan- 
tities of two other kinds of sugar possessing an identical com- 
position, but distinguished by certain chemical as well as by 
certain physical properties. These two varieties of sugar are 
known as grape-sugar and fruit-sugar. That they are formed 
from cane-sugar by addition of the elements of water, is proved 
by analysis, which gives for the new sugars the following 
composition : 

Carbon 4000 

Hydrogen .... 667 
Oxygen 53-3:3 

100 00. 

On dividing these numbers by the respective atomic weights 
of the elements, the following numbers are obtained : 

40 

■; .) = 3*33 carbon. 

I =0 0/ hydrogen. 

:).S-33 
p^-= 3-33 oxygen. 

Ilcncc those two kinds of sugar contain two atoms of hydrogen 
fur every one atom of carbon and one atom of oxygen, and the 
simplest fornmhe for them is CH.jO. This, however, cannot 
possibly represent the molecular formula of the compound, in- 
asmuch as such a simple Ix^dy must either ho a gas or, at any 
rate, a very volatile subsUmce. Neither of these kinds of susrar 
belong to either of the above categories f'*^ <^»i^ heating they 
decomiM»se, leaving a residue of carbon. The molecular formula 



MOLECULAR FORMULAE OF NON- VOLATILE BODIES. Ill 



must therefore be a multiple of the simplest formula. Both 
these sugars yield, on fermentation, equal molecules of alcohol, 
CjHjiO, and carbon dioxide, COg ; hence we may conclude that 
the molecular formula cannot be less than CgHgOg. Both, 
moreover, combine with nascent hydrogen to form manna-sugar, 
or mannitol, which possesses the following composition : 

Carbon 39-56 

Hydrogen .... 7 "69 
Oxygen 52*75 

100 -00. 

As mannitol stands in such a close relationship to grape-sugar, 
fruit-sugar, and cane-sugar, it may be well to calculate how 
many atoms of hydrogen and oxygen these compounds contain 
for every 3 atoms of carbon. Thus we find for cane-sugar, 
C3H3.5O2.75, and for mannitol, C3H-O3. Hence, the simplest 
formula? of these two bodies, consistent with the foregoing re- 
actions, are, cane-sugar, CjoHggOii, mannitol, C^Hj^Og ; and those 
of the two other descriptions of sugar, CjjHjgO^j. That this 
fornuda for mannitol is its molecular furnmla, mav be seen fnnn 
the following considerations. An exact investigation of this 
body has shown that it contains six hydroxyls, or that it is an 
alcohol of an hexad radical. Hence it possesses the fornmla 
CgHg(0H)(5. This may be further proved by a few simple 
reactions. The six hydroxy Is may be replaced by six of hydro- 
gen, hexane, C^H^^, being thus formed, and this is the original 
hydrocarbon of mannitol. It might, notwithstanding, be supposed 
that as mannitol is not volatile without decomposition its mole- 
cular weight might be a multiple of the above numbers. This 
supposition, however, is impossible, as no hydrocarbon can 
contain a larger proportion of hydrogen than is contained in a 
hvdrocarbon of the series C,iH._>„4-2. Ah the three other 
sugars are so clearly connected with mannitol, we may assume 
that the above simple formuhe likewise represent the molecular 
formula3 of these compounds. 

Example No. 11. As a last example of the method by which 
the molecular formula of a non-volatile compound may be 
determined, we will take that of aurin, the analysis of which has 
already been given. This compound is formed when a mixture 
of oxnlic acid, C.^HgO^, and jjIiouoI, C^l^p, \.% warmed with 
sulphuric arid ; water and formic acid, CH^O.„ bcin^^ at the snme 



112 EMPIRICAL AND RATIONAL FORMULAE. 

time produced. As oxalic acid easily splits up on heating into 
formic acid and carbon dioxide, we must assume that the latter 
compound, in the nascent state, acts upon phenol yielding aurin 
and water. If we represent this reaction by an equation, we 
find that of the three formute which we have already given for 
aurin, the second one explains the decomposition most readily : 

8 C,H,0 -f CH ), = Ci„H,,03 + 2H,0. 

That this, the simplest formula, is at the Siime time the 
molecular formula, has been proved, or at any rate rendered 
extremely probable, not only by the fact that aurin can be 
converted into the hydrocarbon triphenylmethane, C^j^H^^j, whose 
derivative it is, but also that aurin can be prepared from this 
hydrocarbon by the replacement of two atoms of hydrogen by 
one atom of oxygen and two atoms of hydrogen by two of 
hydroxyl. 

In the numerous cases to which none of these means for 
ascertaining the molecular weight of a substance apply, we must 
be content to make use of the simplest formula, although it 
must be remembered that in certain cases even the simplest 
formula cannot be obtained. 



EMPIRICAL AND RATIONAL FORMULiE. 

75 Law of the Linking of Atoms, By an empirical formula is 
understood one which simply expresses the composition of the 
body. If at the same time it represents the molecular weight, 
it is termed an empirical-molecular fornmla. Besides these, 
rationed fonnulcc wxQ employed, especially in organic chemistry, 
this name having been first made use of by Berzelius. Such 
formuke are intended to indicate the chemical nature of the 
compound, and to express the relations in which it stands to 
other bodies, or, in otlier words, to i)oint out either the com- 
pounds from which it has been derived or those into which it 
can be resolvi'd. For the true aim of chemistry, as Kekule justly 
remarks, is n«)t so much the study of the existing substance as 
that of its past history and its future development. In the 
historical intriKlu(*tion reference has Ik'CU mtide, not <»nlv to the 
growth of rational fonnuln\ but likewise to the influence which 
the theory (►f types has oxert<»d on our knowh'dgt^ of the |)eculiar 



CARBON A TETRAD ELEMENT. 115 



relations of the atoms in combination and in decomposition. It 

-was formerly supposed that the several constituent atoms of the 

molecule were held together by the attraction which one of 

tliem exerted upon all or upon a large number, and that these, 

ia their turn, exerted a corresponding attraction and thus held 

each constituent in its place. Chemists have, however, now come 

to the conclusion that this attraction is only exerted between the 

atoms severally. The atoms may thus be represented as forming 

a chain, one atom being linked on to the other, so that when one 

of them is removed without altering the position of the others, 

the chain is broken. 

It next remains to notice how this law of the linking of atoms * 
may be explained from the known constitution of the carbon 
compounds. 

76 Carbon is a tetrad element, and, therefore, one atom of car- 
bon unites with four atoms of hydrogen, giving rise to methane or 
marsh-gas, CH^, the simplest of the hydrocai*bons. This hydro- 
gen may be replaced by other monad elements or residues. Thus 
by the action of chlorine we obtain methyl chloride, CHjjCl, 
which, on uniting with ammonia, yields mothylamine, CHgNHg, 
and on treatment with caustic potash is converted into methyl 
alcohol, CH3OH. If two Moms of liydrogen in this latter body 
be replaced by oxygen we obtain fonnic acid, COH.OH. These 
. formulae may be graphically represented ficcording to A. S. 
Couper's suggestion,- as follows, each atom being connected with 
another by means of a line indicating the mode in which the 
attraction acts : 

■if^xi ^ Methvl >r 4.1 1 Methvl Fomiic 

Methane. ^j^j^^.^^ Methylannne. ^^^^.^,j^;^j^ ^^.^ 

H H H H H 

I I I I I 

H— C— H H— 0— H H— C— H H— C— H C=0 



H Ci N O 

/\ 1 I 

li n H H. 

The simplest mode in which two carbon atoms can com- .* 
bine together is when one combining unit of the one atom is 
linked by one combining unit to the other atom. Six free 

' L. Meyer, Modem. Theor. 3te Aitfl. 151. 
« Phil. Mag. [4J, xvi. 104.. 

VOL III. I 



m CONSTITUTIONAL FORMULAE. 



combining units then remain, or a hexad group is formed 
capable of combining with hydrogen to form ethane, possessing 
the following graphical formula : 

H H 
H— C— C-H 



H H 

More than two carbon atoms can combine together in a similar 
way, and the valency of such a group will be increased by two 
units for every atom of carbon whicli thus becomes attached. 
If n atoms of carbon unite together, the number of free 
combining units will be represented by 

2 + n(4— 2)=2 + 27i. 

If the whole of these units be saturated by hydrogen, members 
of the homologous series, CnHsn + s* known as the paraffin 
series, are formed. In these, just as in marsh-gas, one atom of 
hydrogen may be replaced by monad elements or residues, and 
thus the homologous series of chlorides, alcohols, and amines, 
which have been already described, may be obtained. 

77 Derivatives of EtJiane. Ethane, CjH^, forms the following 
derivatives : ethyl chloride, CgH^Cl ; ethyl alcohol, CjH^.OH ; 
ethylamine, CgH^. NHg. The graphical formulie of these are 
readily obtained, and may shortly be written in three diflferenl 
ways, as follows : 

(1) CH, CH3 CH, 



CHj CHa CHj 

I I I 

Cl OH NH, 

(2) CH, CH, CH, 



CH.Cl CHyOH CH..NH2 

(3) CH3.CH2CI CH,.CHj.OH CH,.CHj.NHj. 

Ethyl alcohol, on oxidation, yields acetic acid, one atom of 
oxygen replacing two atoms of hydrogen. 

The question now occurs, which two of the six atoms are thus 
replaced ? This point is determined on ascertaining that acetic 
acid like alcohol contains the radical hydroxy!, a fact with which 



CONSTITUTION OF ACETIC ACID. 115 



the originators of the theory of types were acquainted, for they 
assumed that both these compounds were obtained from water 
by the replacement of one atom of hydrogen by a radical : 

Ethyl Alcohol. Acetic Acid. 

These formulae indicate that ooth compounds contain an atom 
of hydrogen capable of acting differently from the other atoms 
of the same element, inasmuch as this particular one can be 
readily replaced by monad elements or groups. Besides, we know 
that the hydroxyl can be replaced by chlorine when these and 
similar compounds are acted on by phosphorus pentichloridc, 
ethyl chloride, C^HgCl, and acetyl chloride, (J2H3OCI, being 
formed, whilst by the process of reverse substitution the chlorine 
in these bodies maybe readily replaced by hydroxy). Hence it 
follows that the true constitution of acetic acid can only be 
represented by one of the following constitutional formula) : 



(1) 


(2) 


0) 


CH3 


HC - 





0=0 


CH„ 


\0H 



OH OH OH 

In order to ascertain whicli of these is to be accepted, two 
general methods are employed. The molecule may cither l:e 
decomposed by simple reactions into smaller molecules of well- 
known constitution, or it may be built up from such molecules. 

78 The First or Analytical Method, Ejcamplc 1. When acetic 
acid is heated with an alkali, marsh-gas and a carbonate are 
obtained : 

C^HjOgNa + NaOH = CH, + ^^a,C03. 

Example 2. When a galvanic current is passed through a con- 
centrated solution of potassium acetate, acid potassium carbonate, 
free hydrogen, and ethane are produced : 

2 C^HsO^K + 2H2O = 2 KHCO3 + Hg 4- C^H^. 

Tlie change which takes place in this reaction is easily 
explained. When the salt undergo^ electrolytic decomposition, 

I 2 



116 CONSTITUTIONAL FORMUL.^.. 



it first yields the metal potassium and a residue, CgHgOj. But the 
metal at once decomposes water, and the residue yields carbon 
dioxide and methyl, C^HgOa = COg + CHj. The latter body 
cannot, however, exist in the free state, and hence two molecules 
combine to form ethane, C^Rq- 

The most probable conclusion to be drawn from these decom- 
positions is that one atom of carbon of the acetic acid is linked 
directly with carbon, and hence its constitution is represented 
by the first of the above three constitutional formulae. The 
decomposition by electrolysis being represented in the following 
way : 

CHj, CHg 



00. 



H,..H 



CO. 



79 The Seoond <w SifntJictic Method. That acetic acid possesses 
the above constitution and contains the group methyl, is more- 
over ascertained by the fact that it can be synthetically obtained 
from the methyl compounds. Thus, when methyl iodide is heated 
with potassium cyanide, methyl cyanide, CHg.CN, is obtained, 
and this, when boiled with a solution of caustic potash, yields 
potass^ium acetate and ammonia 



I H\ 

C=N + H-O-K + H-O-H = C - O + H-N = C. 



H/ 
OK 

By the action of chlorine upon acetic acid, monochloracetic 
acid, CgHgClOg. is formed. This is a monobasic acid, like 
acetic acid itself, and it is converted by means of phosphorus 
pentachloride into monochloracetyl chloride, CgHjCl.OCl, and 
from this we conclude thai it also contains the group hydroxy 1, 
and that the substitution has taken place in the methyl ^roup. 
Its constitution, as well as that of acetic acid, may, therefore, be 
represented by the following formula^ : 

Ar<'tir Aci«l. Clilor-ftceti«* AcUl. 

(1) CH..CO.OH CH.C1.C0.0H. 

(2) CIL-CO ) f. CH,C1.C0 ) f. 



NON-SATlTiATED COMPOUNDS. 117 



Such or similar forniulai were formerly used, but whilst 
Berzeliu8*s school intended by the use of these formulae to indi- 
cate that methyl is a copulated oxalic acid, the upholders of 
the theory of types distinctly stated that such rational formulae 
are to be considered not as constitutional formulae, but as for- 
mula; of decomposition, simply indicating the chemical meta- 
morphoses of the substance in question and its relationships to 
other substances, but in no way indicating the constitution or 
position of the atoms. 

All the formulae for acetic acid which have been mentioned 
indicate (1) that it contains two atoms of carbon connected 
together by the simplest method of linking; (2) that one of 
these atoms is combined with three atoms of hydrogen ; and (3) 
that the other is so connected with two atoms of oxygen that 
one of the atoms of this latter element is linked to carbon with 
both its combining units, the other being connected with only 
one combining unit, its second combining unit being saturated 
with hydrogen. 

8o Noil-Saturated Com2'>ouiids, If we remove two atoms of 
hydrogen from ethane, ethylene or olcfiant gas, CgH^, is pro- 
duced, and this substance is sharply distinguished from ethane. 
The latter, like all paraffins, is attacked by chlorine and bromine 
only in daylight, and with the formation of substitution-products, 
wliilst ethylene and its homologues unite directly in the dark with 
two atoms of the above halogens. Hence we may assume that 
the latter hydrocarbon belongs to the class of unsaturated com- 
pounds or contains free combining units. In this case the 
constitution of ethylene may be represented by the following 
formulae : 

CH, — CH., 

I I " 

=CH — CHj 

It is, however, as we shall see later, much more probable 
that the two carbon atoms are connected together by two com- 
bining units of each, and that the constitution is expressed 
more correctly by the formula : 

CH, 



CH, 



The easy combination of ethylene with the elements of the 
chlorine group can in this case be readily explained by the 



118 CONSTITUTIONAL FORMULAE. 

tendency which the carbon atoms exhibit to combine in the 
simplest possible way. However this may be, it can be easily 
shown that the first of the above formulae does not indicate the 
constitution of ethylene. 

The bromine in ethylene dibromide, CgH^Brg, can readily be 
replaced by hydrpxyl, and by the action of hydrochloric acid on 
the glycol, C.2H^(OH)2, thus produced, ethylene chlorhydrin, 
CgH^ClOH, is formed. This substance on oxidation yields raono- 
chloracetic acid, CoHgClO.OH. Hence it follows that the above 
compounds possess the following constitutional formulae : 

Etliylenc Ethylene Alcohol or Ethylene Mono-chlor- 

Dibroinide. Glycol. Chlorhydrin. acetic acid. 

CH-Br CH0.OH CH2CI CH2CI 

I I " I I 

CH^Br CH2.OH CHjOH CO.OH. 

By a moderate oxidation ethylene alcohol can be converted 
into glycollic aciid, C2H^03, by replacement of two atoms of 
hydrogen by one atom of oxygen. This reaction is exactly 
parallel to the formation of acetic acid from ethyl alcohol, 
and hence the following formula must be given to glycoUic 
acid: 

CH..OH 



CO.OH. 

The truth of this is easily proved by the fact that glycollic 
acid is also formed when a salt of chloracetic acid is boiled with 
water : 

CH.Cl CH2.OH 



+ HOH = I 4- KCl. 

CO.OK CO.OH 

Glycollic acid contains two hydroxyls in different positions ; 
one of these may be termed the alcoholic hydroxyl, because it 
tjccupies the same position as the hydroxyl in alcohol, whilst the 
other playing the part of the hydroxyl in acetic acid, and capable 
of having its hydrogen replaced by metals, is, on this account, 
tailed the basic hvdroxvl. 

-fVs wc may assume that analogous constitution gives rise to 
analogous properties, we may predict that glycollic acid will act 
jMirtly as an alcohol and partly as an acid. This is found to be 
the case. Kxnctly as we obtain ethyl chloride by acting on 



T20 ISOMEmiSM. 



and this was confirmed by the discovery in tlie following year 
by Wilham Henry of the existence of a 8imilar hydrocarbon in 
coal-^as. Didton states ** that the hydrocarbon contained in 
oil-gas is a compound sui generis consisting of the elements of 
defiant gas united in the same proportion, but differing in the 
number of atoms, most probably the atom of the new giis 
consisting of two of o!efiant gas." 

This hypothesis was soon proved by Faraday to be correct. 
In the year 1825 he published a communication " On certain 
new compounds of carbon and hydrogen obtained by the decom- 
position of oil by heat."* At that time a Portable Gas Company 
was established in London for supplying the public with the 
gas obtained from the distillation of oil, and pumped under a 
pressure of 30 atmospheres into portable vessels. A considerable 
quantity of a liquid was in this way condensed, and this liquid 
was examined by Faraday. It readily evaporates under the 
atmospheric pressure, and, like olefiaut gas, has the power of 
uniting with its own volume of chlorine to form an oily liquid. 
Its specific gravity proved to be double that of olefiant gas, and 
its chloride contains twice as much carbon and hydrogen as 
Dutch-liquid, this being the name which was at that time given 
to the oil of olefiant gas from its discoverers. 

Shortly before this, Liebig - had shown that the salts of ful- 
minic acid |x>ssess exactly the same composition as the corre- 
sponding salts of cyanic acid. In a note to his memoir ^ Faraday 
refers to this di.scoverv, and adds the foUowinif remark : — " In 
reference to the existence of bodies composed of the same 
elements, and in the same proportion, but differing in their 
qualities, it may be observed that, now we are taught to look 
for them, they may probably multiply upon us." 

Notwithstanding these early observations, many chemists 
believe<l that some error had been made in the analyses of 
these substances. Thus, Bi.»rzelius was una])le to conceive that 
bodies could exist having the s:une composition but possessing 
tijtally different i)roiK»rties. When, however, Wohler proved in the 
year 1828, that ammonium cyanate can be converted into urea, 
ami when BiTz.-lius liiiuself ten years later showed that raccmic 
acid and tartaric acid have the s:ime coini)osition, the fallacy 
of the old axiom Ix/caine evident, and it was generally acknow- 
li-dged that cht'iiiu-al conij)ounds possessing the same qualitative 

» Phil Tnnis. 182.'.. 440. > Ann. Lhim. Phya. xxiv. 298. 

^ L*c. (it, ji. 460. 



ISOMEKISM IN THE RESTRICTED SENSE. 121 



and quantitative composition need not necessarily exhibit the 
same physical and chemical properties/ 

Berzelius himself admitted that the doctrine of isomerism 
had now been completely confirmed, inasmuch as the same 
number of the same elementary atoms arranged in different 
ways not only may give rise to compounds having a dissimilar 
crystalline form, but exhibiting distinct chemical properties. 
To compounds of the latter kind Berzelius gave the name of 
isomers (from la-ofieprj^; ; lao<: equal ; fiepo^, a share or portion), 
and soon afterwards he divided these, on the one hand, into 
those to which we now give the name oi polymeric compounds, 
because they possess a diflferent molecular weight, and, on the 
other, into those termed mctamcric bodies, which, with an 
equal molecular weight, exhibit different properties. 

Since Berzelius's time a large number of such bodies have 
been discovered. The radical theory and the theory of types 
are capable of explaiuing many cases of isomerism, but it was 
not until the doctiiue of the linking of atoms was established 
that a clear light was thrown on this subject. 

The causes which can produce isomerism are numerous, 
and hence we must divide isomeric bodies into different groups. 

82 Isomei'ism in the Eestrided Sense. The compounds classed 
under this head all contain carbon atoms in direct combination, 
and their isomeridcs have the same n\olecular weight. 

Let us in the first place investigate the cause of those cases 
of isomerism which can be predicted by theory, and notice how 
far these predictions have been found to agree with the facts. 

The simplest hydrocarbons are those of the series C„H2n + 2. 
It is clear that in this series, cases of isomerism can only occur 
when the carbon atoms are combined in different ways with one 
another. Hence the three first terms of the series cannot give 
rise to isomeric forms, and the following substances are the only 
ones known : 

Methane. Ethane. Propane. 

CH, 



CH3 



CH, I CU, 



CH3 



2 



CH3. 



The fourth term, C^U^q, of the series is derived from propane 

» Pojj. xix. 326. 



122 



ISOMERISM. 



by the substitution of one atom of hydrogen by methyl. 
This replacement may, however, take place either at the end 
of the chain of carbon atoms or in the central carbon group. 
Hence two isomerides exist and both of these are known : 



Butane. 

CH, 

I 
CH, 

I 
CH, 

I 
CH, 



Isobutano. 

CH, 



I 



3 



CHj — C — CH3 
CH, 



Three isomerides of the next member of the group, CgHj^, are 
possible, and these are all of them known : 



Pentone. 

CH, 

I 
CH. 



Isopentane. 



CH3 CH, 



Tetramethylmethane, 



CH. 
CH, 
CH, 



\ / 
CH 

I 
CH, 

CH, 



CH 



3 



CH,— C— CH, 

I 
CH, 



The number of possible isomerides increases rapidly as wo 
ascend the scries. This is seen by the following table : ' 



( 



No. of carbon atoms .... 



, So, of |>ossil<le isonivric paraffins 



1 '234 



5 G 



78 9 



I I 
1112 



10: 11 



12 i 18 



3.5.9 '18 35 75 159 357 799 

I I I I I • I ' 



Of these, however, only a relatively small number has as yet 
been prepared. 

When an atom of hydrogen in a paraffin is replaced by 
a monad element or radical, the comiK)und3 of the alcohol 
Ttodioals are obtained. In this case isomerism commences in 
the third series, and two propyl alcohols, CaH^O, are known, 
viz. : 

' Cayler, "On the analytical furmn rallotl trwji, with applications to tho 
tlieon* of chrniioal conihi nations," Jirit. j-lstnr. Hep. 1S75, 257. Kor'alrnlattHl by 
l>r. Hermann of Wiiitzburg. thf two Inxt an' 3.'i5 an<l *^<"2. 



ISOMERISM IN THE RESTRICTED SENSE. 123 



Primary Secondary 

Propyl alcohol. Propyl alcohol. 

CHq CH- 

CHj CH.OH 



CHo. 



2.0H CH3 



Four butyl alcohols, C^Hj^O, can in like manner exist accord- 
ing to theory. These are all of them known^ viz. : 



(I) 

rimary 
oimal. 


(2) 
Secomlary 
Koriual, 


(3) 
Iso-alcohol. 


w 

Terti«i7. 


CH, 
CH, 


CH3 

CH, 


CH« CH« 

\V ' 


CH, CH, 
\ / ^ 


M 


■• 


CH 


C.OH 


CH, 


CH.OH 


CH».OH 


CH, 


CHs.OH 


CH, 


M 


90 



Nine pentyl alcohols, C^HjoO, can exist according to theory, 
of which only seven are as yet known. 

If two atoms of hydrogen in a paraffin be replaced, isomeric 
comi)ounds are obtained in the second term of the series. 
Thus we have : 

Ethyleue Giloride. Ethideno Chloride. 

CHgCl t^Ha 



CH2CI 



CHClj 



The chloride CaHgClg can exist according to theory in four 
modifications : 

. (1) (2) 

Trinictliene Projjylene 

Chloride. Chloride. 

CHoCl CH3 

CH2 CHCl 

I I 

CH.,C1 CH^Cl 

In the case of the hydrocarbons, CnHon, a larger number of 
isomerides can exist than is possible in the case of the marsh- 
gas series. Thus, for example, we know^ only two butanes but 
three butylenos : 



(3) 

Propidene 

Chliiride. 


Propionene 
Chloride. 


CH, 

CCI, 


CH, 
CH, 


CH, 


CHC!, 



124 ISOMEUISM. 



a-Butvlcue. ^-Butylcne. Isobutylene. 

CH3 CH, CH3 CH, 

I I \/ 

CHg CH C 



II II 

CH CH CHj 



CHg CHjj 

It has already been stated that the hydrocarbons of the series 
CnH2n have been assumed to contain free combining units. If this 
wer^ the case, four propylenes and eight butyl enes must exist. 
If, however, these hydrocarbons be supposed to contain two 
carbon atoms having a double linking, only one propylene and 
three butylenes can exist, and this has been proved to be the 
fact. 

In the case of the hydrocarbons of the series CnH2u-2» a still 
larger number of cases of isomerism are possible. Thus, for 
instance, we have two substances having the formula CjH^. 



Allylene. Iso-allylcne. 

CH3 CHj 

II 

c 



i 



CH CH., 

A large group of carbon compounds are derivetl from benzene, 
Cgll^,. In these the carbon atoms are linked together in a 
peculiar way, the nature of which will be hereafter explained. 
The homologucs of this series are formed by the replacement 
of one or more atoms of hydrogen by alcohol radicals, and 
hence a variety of isomerides is formed, such as the foUovsing: 

(1) (2) 

Kthyl-lwiizoiio. Dimethvl-bcnzeiie. 

(1) (2) (3) (4) 

IVopyl- Isopropyl- Mctbyl-cthyl- TriiuHthyl- 

bi'iizeue. K'uzeiie. benzene. bonzrnt*. 

c.Hj.c^H- c,h,.(;h,ch,;, c«h,|J!'J|' c,H3|(!h;; 

V^ Oil 



• mch. 



3 



The foregoing cases do not, however, oxliau t the number of 
r.xisting isomeric bodies, inasniuch as two or moio atoms of 



METAMERISM. 125 



hydrogen in the benzene may be replaced, and this replacement 
may take jJace in diflferent positions in the molecule. Thus, as 
will be seen hereafter, there may be three isomerides having the 
composition of dimethyl-benzene, of methyl-ethyl-benzene, and of 
trimethyl-benzene ; thus four hydrocarbons having the formula 
Cj,Hj(j exist, and eight having the formula C^H-y 

In these compounds, moreover, not only the hydrogen in the 
alcohol radical, but that in the benzene residue may be replaced 
in different positions, and thus the existence of a still larger 
number of isomerides in the benzene derivatives becomes 
possible. 

83 (2.) MetamcrUm, The compounds classed under this head 
possess the same molecular weight, but contain two or more 
carbon groups connected together with a divalent or polyvalent 
radical. The number of bodies which may thus be grouped 
together is very large. A few simple examples will here suffice. 
If an atom of hydrogen in an alcohol be replaced by an alcohol- 
radical, an oxide or ether is obtained. Thus the following 
substances can be obtained, all having the composition CgHj^O. 

(1) (2) (2) 

3Iethvl-i»entyl Ethyl-butyl Dipropyl 

ether. ethor. ether. 

CH3 ) ^ C..H, \ ,-. C,H. 1 ^ 

c^Hu / ^ c:h; / o c;h; } o- 

Inasmuch, however, as the radical propyl can exist in two 
isomeric forms, butyl in four, and pentyl in nine, it is possible, 
according to theory, that sixteen ethers having the above general 
formula may exist. 

The so-called compound ethers or ethereal salts form a very 

important class of isomeric bodies. Thus, for example, the 

following compounds of the general formula C^H,oOo are 
known : 

(1) (2) (3) 

Metliyl Ethyl Propvl 

pentylate. butynite. propionate. 

CH3I0 C.,H,)n C,HaA 

and in this case the variety of constitution exhibited by the 
radicals leads to the formation of eight distinct isomerides. 

As a last example the amines having the general formula 
CjHgN may be cited : 



126 ISOMERISM. 



(1) (2) (3) (4) 

Propylamine. Isopropylamine. Methylethylamine. Trimethvlamine. 

(C3H. rCH(CHJ. fCH, jCH- 

(H (H (h (CH3. 

The two first substances are isomeric compounds, the others 
metameric. 

84 (3.) Polymerism. This division contains compounds pos- 
sessing the same composition, but differing in molecular weight. 
The hydrocarbons of the series CnH^ may serve as an example : 

Ethylene C.,H^ 

Propylene ^3^5 

Butylene C^Hg 

Pentylene ^5^10. 

The following compounds are also polymeric : 

Acetylene ..... CgHg 

Benzene C^,Hg 

Styrolene CgHg 

Uihydronapthalene. . CiqHj^j 

Tetrahydroanthracene . Cj^Hj^ 

Distyroleno .... CigHj^. 

As another series we have : 

Formyl aldehyde . . CH2O 

Acetic acid .... C^H^O, 

Lactic acid .... CjH^O, 

Grape sugar . . . C^HjjO^ 

And again : 

Acetaldehyde . . . C^H^O 
Butyric acid . . . C^HgOg 
Paraldehyde . . . C^Hi^Oj. 

85 (4.) Physical Isomerism. A number of bodies are known 
which according to their general deportment must be considered 
to possess the same chemical constitution, but which exhibit 
certain distinct differences in physical properties. Thus, they 
may crystallize in different systems or possess different melting 
points. These substances can readily be converted from the 
one into the other modification, and their isomerism is probably 



POLYMERISM. 127 



due to a different arrangement of their molecules, analogous 
to the dimorphous and trimorphous inorganic compounds. 

Many carbon compounds possess the property of rotating the 
plane of polarization, and such compounds generally exist in 
two or three modifications, assuming distinct optical properties, 
as for instance that of turning the plane of polarization more or 
less either to the right or to the left. In the case of crystalliz- 
able compounds this difference is rendered evident in the 
existence of hemihedral faces, which in one modification lie 
to the right in reference to the other faces, and in another 
modification lie to the left, so that the one crystal is the 
reflected image of the other. In the case of liquids a similar 
difference in molecular structure is exhibited in the phenomenon 
known as circular polaHzation, a property which is possessed by 
a large number of organic liquids. It has been pointed out by 
vant Hoff ^ and LeBel,- that all optically active bodies contain 
one or more assymetric carbon atoms. By this is meant a 
carbon atom connected with four dissimilar groups of atoms, 
as shown by the following examples : 

Optically active ,«■ i. ., 

^yl alcohol. ^'*^^^ ^»^- 



C^Hj CO.OH 




H2.OH 




Hence we may conclude that optical isomerism is probably 
caused by different relative arrangement of the atoms which 
form the molecule. Further information on this point will be 
given under special heads. 

86 (5.) Unexplained Isomerism. Lastly, cases of isomerism 
occur for which, up to the present, we have no sufficient expla- 
nation. Many cases of this kind have been long observed, but 
some of these have disappeared on finding that the differences 
were merely due to impurities contained in the substances. 

On the other hand, cases are known of distinctly pure sub- 
stances differing in their chemical properties and yet possessing 
the same constitutional formulae. This, however, is not any 

1 Xa Chxmie dans VEspace. ' Bull, Soe, Chim, [2], xxii. 837. 



128 CLASSIFICATION OF THE CARBON COINIPOUNDS. 



contradiction to the law of the linking of atoms, as might be 
supposed, but simply points to the conclusion that graphical 
formulae cannot represent the arrangement of the atoms in 
space, about which, in fact, nothing is known. These rational 
formulae possess a somewhat similar meaning to the parallelogram 
of forces in mechanics. They simply serve to give us a notion 
of the attraction which the single atoms in the molecule exert 
upon one another. 

Compounds in which the isomeric relations cannot yet be 
explained, can as a rule be readily transformed one into the 
other. 



CLASSIFICATION OF THE CARBON 

COMPOUNDS. 

87 The carbon compounds may be classed in different groups 
according to the mode of linking of the carbon atoms. 

I. The Fatty Group, To this belong all compounds in which 
the carbon atoms are connected together by a single linking as 
in the paraffins and their derivatives. The group receives its 
name from the fact that several of its compounds, such as the 
acids of the series CnHouOa and others, occur in the fats of 
animals and plants. A characteristic property of these sub- 
stances is that their chemical metamorphoses are principally 
brought about by substitution, that is, by one atom or group of 
atoms being removed and other gniups occupying their places. 
For this reason the members of the fatty group have also been 
termed saturated compouwh, 

II. CompouiuJs containing rdatirelif less Jnjdrogen than the fore- 
going. These contain carbon atoms united by double or triple 
linkage. Tlie hydrocarbons which belong to this group form the 
following series : 

<;h.„.. 

These compounds, as well as their substitution-products, are 
termed unsaturated comjwxnuh, as they possess the characteristic 
property of combining directly with hydrogen or with the 



TIIK A150MATIC GliOUP. 120 



elements of the chlorine group or their hydracids, and thus 
become saturated compoundH hy addition. Tliis is caused by the 
nipture of one of the links of a doubly-linked carbon atom. 
The inverse operation can also be carried out, and the various 
hydrocarbons of this group can readily be obtained by the 
removal of hydrogen or chlorine from the saturated fatty 
compounds. 

III. The Aromatic Grouf. The compounds belonging to this 
group are relatively much richer in carbon than those of the 
fatty group. In many chemical metamorphoses, however, they 
resemble the members of the latter group, as for example in 
their power of readily forming substitution derivatives. Only 
in rare instances do they yield additive products, and these, . 
it is important to note, are not fatty bodies. Thus, for instance, 
the simpler hydrocarbons belonging to this series and having the 
general formula CnH^n-o are isomeric with the compounds of 
the second group of bodies, containing relatively less hydrogen. 
But whilst these latter by the addition, for example, of bromine, 
yield octobromides, CjjH^jBr^, only six bromine atoms can bo 
added to the simplest aromatic hydrocarbon yielding the hex- 
bromide, CgH^jBr^. Hence we conclude that these compounds, 
rich in carbon, consist of groups of do^d chuim, each containing 
six atoms of carbon. The name arom/itic group has been given 
to these because many of the bodies belonging to the group 
are contained in ethereal oils, balsams, gum-resins, and other 
bodies posseseing an aromatic smell. 

IV. Compoiuids of Unknown Constitution, A number of the 
compounds occurring in the vegetable and animal organism, 
possess constitutions so complicated that their determination has 
hitherto not proved possible. Indeed, not many years have 
elapsed since this remark applied to by far the larger number 
of organic compounds. By degrees, however, this group is be- 
coming smaller, and in process of time it will doubtless entirely 
disappear. 

88 Different Methods of Clas.nfication, Each of these chief 
groups contains several subdivisions, and these may be arranged 
in different .ways. Perhaps the most systematic method of 
arrangement would be to commence each group with a discussion 
of the hydrocarbons, and then to follow on with a description of 
the series of substances obtained by the replacement of one, 
two, three, or more of the constituent atoms of hvdrogen. 
Such a method of classification, however, lal>»ur8 under the 

VOL. 111. K 



130 CLASSIFICATION OF THE CAKDON COMPOUNDS. 

disadvantage that compounds which stand as a rule closely 
together, as, for example, the alcohols CnH2ii+20 and the acids 
OnH2ii02, are thus found widely separated, whilst other groups 
possessing but little analogy, except m their empirical formulae, 
are brought into proximity. 

Hence it is desirable, alike for the sake of perspicuity as for 
the purpose of showing the genetic relationships existing be- 
tween different bodies, to depart, in many cases, from such a 
systematic treatment and to arrange the compounds according 
as they are derived one from the other.^ 



FATTY BODIES AND COMPOUNDS CONTAINING 
RELATIVELY LESS HYDROGEN THAN THESE. 

89 Hydrocarhons of tlic Series C^-Hin+s or the Paraffin Series. 
Before the year 1848 none of the hydrocarbons belonging to 
this class were distinctly known, with the single exception of 
marsh-gas, the first term of the series. Chemists had, however, 
met with other members of the series, and had examined their 
properties, but their true nature was not fully understood. 
In the above year the investigations of Kolbe ^ on the electro- 
lysis of the fatty acids, and those of Frankland ^ on the action 
of zinc on the iodidus of the alcohol radicals, opened a new 
field of investi«jfation which soon yielded a rich harvest. The 
hydrocarbons thus obtained were considered, from their mode of 
production, as the free radicals of the alcohols.* Gerhardt, 
however, proiX)sed to double their formulas in order to bring 
them into co-ordination with Avogadro's law, and he con- 
sidered the so-called radicals to be homologues of marsh-gas. 
Hofmann* also gave his adhesion to this duplication of the 
formulae, pointing out that the adoption of Kolbe and 
Frankland's formuhe led to an increment in the boiling 
point for each increment of CHj, double that known to exist 
in other homoloijous series. 

Toi(ethtT with the radicals Frankland discovered what he 
believed to be a distinct series of hydrocarbons. These were 
obtained by the replacement of the iodine in the iodide of the 

» Kekule, Lchrbuch, i. 225. 

• Ann, ChcvL Vharm. Ixix. 279 ; Chem, Soc. Jovm, ii. 157. 

' " On the Isolation of tho Organic ItailicaU," Chem. Soc. Juurn, ii. 263 ; 
iii. 30 ; iii. 322. 

* Gerhanlt and Uurent. Cumf>t. Jlnid, 184P, 19; 18.''i0, 11. 
» Chan. Soc. Jouni, ii. 121 (1850). 



HYDROCARBONS OF THE PARAFFIN SERIES. 131 

alcohol radical by hydrogen. Ho assumed these hydrides to be 
the true homologues of marsh-gas, and according to the views 
first expressed by Brodie,^ these were believed to stand in the 
same relation to the radicals as the alcohols to their ethers : 

Ethyl hydride. Ethyl. 

H ] c,H, r 

Ethyl alcohol. Ethyl ether. 

Brodie likewise predicted the existence of mixed radicals, 
bodies standing in the same relation to the simple radicals 
as Williamson's mixed ethers do to common ether : 

Ethyl ether. Ethyl. 

C,H, ] ^ C,H, ] 

Ethyl-amyl other. Ethyl-amyL 

C5H11 ) C5H11 3 • 

Such mixed radicals were soon afterwards isolated by Wurtz, 
who obtained thom by the action of sodium on a mixture of the 
two iodides, as well as by the electrolysis of a mixture of two of 
the fatty acids. It was at this time generally believed that a 
real difference existed between the hydrides and radicals, the mole- 
c'lle of the latter being supposed to consist of two atoms. Still 
it seemed remarkable that the isomeric members of two such 
differently constituted groups not only do not differ in physical 
properties, but even exhibit a close analogy in their chemical 
characters. Indeed this similarity led Greville Williams,- who 
discovered many of the hydrocarbons of this group in the 
products of distillation of Boghead cannel, to consider them as 
radicals, chiefly because the several members differed from one 
another by the increment O.,!!^. 

The chemical reactions of the radicals were at that time but 
incompletely known. One point, however, was ascertained, 
namely, that when a<;ted upon by chlorine the radicals did not 
yield, as might have been expected, two molecules of the corre- 
sponding chloride, but two or more of the atoms of hydrogen 
of the hydrocarbon were found to be replaced by chlorine. 

» Clum. Soc Jaum. iii. 405 (1851). « PhiL Trans. 1857, 447. 

K 2 



1.02 KADICALS AND IIYDUIDES. 



The next point requiring examination was tlie action of 
chlorine upon the hydrides. Duimis had already found that 
the first substitution-product of marsh-gas is the compound 
CH3CI, and Berthelot had shown that* this substance is identical 
with methyl chloride. On the other hand, Frankland and 
Kolbe had obtained from ethyl hydride the chloride C^H-Cl, a 
substance which they believed differed from ethyl chloride.^ 

90 It was not until the year 18G2 that our knowledge of 
this point became precise. In that year Pelouze and Cahours '-* 
showed that American petroleum consists almost entirely of a 
mixture of homologous hydrocarbons of the series CnHon^2» a^J 
Schorlemmer^ found the same in the distillation-products of 
oannel coal. The examination of these latter products showed 
that their monochlorinated substitution-products are really the 
chlorides of the alcohol radicals from which the alcohols and 
their other derivatives can be prepared, and hence that the 
hydrocarbons themselves are hydrides. 

The next question was to ascertain precisely the nature of 
the action of chlorine upon the radicals themselves, ami 
Schorleminer* found that the two following : — 

Etlivluinvl ami Di-amyl. 

c.h/i C,H„) 

O.H,J C,H,J 

yielded, respectively, chloride of heptyl, C^Hj-Cl, and chloride 
of decatyl, CioHmCl ; and from these the coiTesiX)nding alcohols 
were prepared.^ 

He further proved that the radical methyl, or di-mothyl, as 
it was afterwards called, is identical with hydride of ethvl, 
inasmuch as not only did the existence of the differences which 
had been previ»)usly observed between their physical properties 
prove to be a fallacy, but both bodies were converted on treat- 
ment with chlorine into ethyl chloride. About the same time 
Schiiven ^ showed that Frankland's di-ethyl was converted bv 
chlorine into butvl chlorMe. 

From this time forward the supposed distinction between 
radicals and hydrides may be said to have completely broken 

* Chrm. StiC. Journ. i. 00. 

' Aiin. Chim, Vhyn, [4J, i. 1 ; Ann, Chnn, Phnrm. cxxiv. 289; cxxvii. ll»0; 
cxxix. 87. » Chr,H. .SW. Juitrn. xv. 411» (1802). 

* ('hem StK\ Jovrn. xvi. 4'2.V • Prtii^. Una. S>n'. xiv. I'.A. 

* Ann, C/"tH. Phaim, rxxx. *203 ; rxxxi. 70 ; oxxxii. 'I'M. 



PARAFFIN HYDROCAKBOXS. 133 



down, and it was acknowledged that in the formation of 
the radicals two carbon atoms are combined exactly in the 
same way as they are connected together in the other com- 
pounds. That, for instance, in the radical di-methyl, the 
two carbon atoms are connected together exactly in the same 
way as the two carbon atoms are Unked together in the ethyl 
compounds. 

The lower members of this series are very volatile liquids. 
The boiling point rises with each increment of CH^, and the 
highest members are crystalline solids. A mixture of these latter 
substances was discovered in the year 1830 by Reichenbach ^ 
in wood-tar. This was believed by him to be a definite chemical 
compound, to which he gave the name of paraffin^ from parnm 
affinis, its most important characteristic being its inactive 
properties. For a long time it was believed that paraflBn 
belonged to the series of hydrocarbons, C„H2n, for in those 
days, as has been stated, the only member of the series CnH2n+2 
known was marsh-gas. Moreover the percentage compositions 
of the higher members of these two groups exhibit diflFcrences so 
slight that they fall within the errors of analysis, and it becomes 
impossible thus to determine to which of the two groups a 
substance belongs. This can, however, be readily ascertained 
when the substances are treated either with chlorine or bromine. 
These elements combine directly with the group CuH2ni but act 
with difficulty on the group CnH.>n+2, giving rise to substitution- 
products. In addition to this, the members of the first of these 
groups are easily attacked by oxidizing agents, whilst those of 
the latter group are only oxidized with difficulty even by the 
most energetic reagents. In this respect paraffin distinctly 
belongs t^ the latter class.^ On these grounds Henry Watts ^ 
has suggested that the name of paraffin should be made 
generic, and apj^lied to all the members of this series of these 
hydrocarbons. 

The paraffins are not attacked in the cold either by chromic 
acid, concentrated nitric acid, or sulphuric acid, or even by a 
inixture of the two latter acids, but if they are heated with 
dilute nitric acid, with chromic acid, or with a mixture of 
manganese dioxide and dilute sulphuric acid, they are slowly 
oxidized, the greater portion being completely converted into 

* Jahrh. Chem, PJnjs. (Sclnvcig^-Seidtl) xxix. -lUG. 

- iVwm. Soc, Journ. xv. 419. 

' Fownes, Manual of Chemistry, Tenth Edition, 5 IS. 



134 PROPERTIES OF THE PARAFFINS. 



carbon dioxide and water. By the action of nitric acid, small 
quantities of the fatty acids as well as succinic acid and nitrates 
arc produced, whilst by oxidation with chromic acid a small 
quantity of acetic acid is formed.^ Chlorine, in the daylight, 
attacks these hydrocarbons but slowly. The liquid become.-} 
warm, hydrochloric acid is evolved, and mouochlorides are fir::t 
produced. These, however, are readily converted, in the presence 
of nascent chlorine, into higher substitution-products. But the 
formation of this latter class of bodies may be prevented to a 
great extent by passing chlorine into the vapour of the slowly 
boiling hydrocarbon instead of into the liquid itself.^ The ex- 
planation of this being that the mouochlorides are less volatile 
than the hydrocarbons from which they are produced, so that they 
condense as soon as they are formed, and thus the chlorine comes 
almost exclusively in contact with the vapour of the hydro- 
carbon. The apparatus must, however, be protected from the 
direct sunlight, as otherwise complete decomposition takes place 
with evolution of light and heat and deposition of carbon. 

When the mouochlorides are treated with chlorine, further 
substitution takes place, but it is only in the c^ise of the two 
lowest terms of the series that the whole of the hydrogen can be 
replaced by chlorine. Propane, Cgllg, can be converted into 
hexchlorpropane, CjHgClQ; and hexane yields hexchlorhexane, 
CgHgClg as an end product, and even these are formed with 
difficulty. For in order to obtain these bodies, the decomposition 
must not only be carried on in the sunlight, but as soon as the 
action of the chlorine becomes feeble, iodine must be added.^ 
The action of this latter element dejiends upon the formation 
of iodine chloride, whirh readily decomposes into its elements 
the liberated chlorine in the nascent or atomic condition acting 
more energetically than the same element in the molecular 
state. Then the nascent iodine combines anew with chlorine, 
and thus it plays a similar part to that of the oxides of nitrogen 
in the sulphuric acid manufacture. The chlorination of the 
paraffins can, however, be carried out further by heating the 
chlorinateil products in closed tubes, together with chloride of 
iodine, under increased pressure. Propane thus treated yields 
in the first pla^e octochlorpropane, C^Cl^, and this, by further 
action of chloride of iwliue, is converted into hexchloretbane, 

* Si'horlfininor, Jim. Ch m. Phnnn, cxlvii. 214. 

* Schorlciiiiiirr, /Vi/7. Trmin. 1871. 

^ Sihurli-muuT, P-nc. Hoy. S-.m-. xviiL 29. 



NORMAL AND ISO-PARAFFINS. 



135 



CgClg, and tetrachlormethane, CCl^. Under the same con- 
ditions hexane yields, together with the two latter compounds, 
bexchlormesol, C^Clg, and hexchlorbenzol, C^jClg.^ 

Bromine likewise yields substitution-products, but not so 
readily as chlorine,^ but by the action of excess of bromine 
under the influence of heat and pressure, substitution-products 
are formed similar to those which are obtained by the action of 
chloride of iodine. 



CONSTITUTION OF THE PARAFFINS. 

91 The paraffins whose constitution is known may be classed 
under four groups. 

(1) The Normal Paraffins, In these the carbon atoms are 
connected together by simple linkage, no one atom being con- 
nected with more than two others. Of these the following have 
been examined : 



Methane 


CH, 


Boiling 
point. 

gas 


Heptane, 


C7H16 


Boiling 
point. 

98°-4 


Ethane 


C,H, 


gas 


Octane, 


C^s^is 


125° 


Propane 
Butane 
Pentane 
Hexane 


C4H10 


gas 

r 

38° 
70° 


Nonane, 

Dodecane, 

Hecdecane, 


^12^26 
^16^32 


148° 
202° 
278°. 



(2) Isoparaffins. These contain an atom of carbon connected 
with three other carbon atoms, the other carbon atoms being 
joined by single linkage. The following members of this series 
are known : 



Trimethylmethane, C H 



Boiling point. 

CH, 

ch; - 17' 
ch; 



3 



Dimcthylethylmethane, CH^ CJH.^ 

( aH, 



4- 30' 



1 Kwirt and Mfiz, Bet. Druts-h, Chrw. Ox. viii. 120rt; KraflTt, ih. 
:. 801. « Schoilemnier, PhU. Tmus. for 1877, p. 41). 



KraflTt, ih. ix. 10S5 ; 



130 CONCTITUTrON OF THE PAKAFFINS. 



• 113 



f OH, 
Methyldiethyhuetliauc, CII-; CHj GO 

Dimethylpropylmctliano, CH-( CH., (i2 

( oX 

(CH, 
Dimcthylbutylmethanc, CH- (!H., 91 



( < '.H, 
Triethvliiwjtlumo, ( IH -J ( CH" 



'.Hi' 



Diinethylhcptylinethaue, CH-{ OH, loo°. 

(aH,. 

>« I la 

(3) Mesoparajjiiis. lu these two or more carbon atoms occur, 
each connected with three other atoms of carbon. The name <>f 
this class is derived from the fact that they stand between the 
foregoing class and the group next following (fieao^, middle).^ 
The followin^j terms of this series are known : — 

Boilin;; point. 

Tetramctliyl(thaiie(CIIj)j:H.(H(rH3)- 5b' 

'lViniinethvnmt:iiie(<'n;,)„('H.CH-.CH2.CH(CH.,) lOlP 

P. iitamethVlbntfiin* (('M;,)>H.nit<'Il3)CI{3.CH(CH.,) 130" 

Ti'tramethylhexaiie (CHaM'n.^'H-.ClIa Cn2.C'H,.CH(('IIa), . . n'2\ 

(4) Nvopftrt(J/ins. lu those comiwiunds one atom of carbon is 
connected with four otlirr carbon atoms. From havm*'' been 
lately discovenMl they have received the above name. The 
following have Iktu prrjiarfd : 

Boiling ]ioiiit. 
Tetramethylmtthane, ('((/H.^^ l)'-.> 

Trimethvlethylmethanis ( ' i ^f! \V' 45'' 

Dimcthyldiethylmethane. C'-[ [?}l?\ 86'. 

92 JFodrs of Prrparah'cm. Various m(»rh(>ds may bo employed 
for the preparation of the iiaralHns. Some of them con.sist in 
bringing together two alcoliol radicals, and thus effecting direct 

» Odling, rhil, Mtt'j. [:»J, i, 1(5. 



PREPAR'ATIOX OF THE PARAFFIKSf. 137 



synthesis, as in reactions 1 and 2. Another method, as in re- 
actions 4, 5, and 6, is that of liberating the alcohol radical from 
a compound and bringing it into combination with hydrogen. 
Paraffins are, therefore, obtained by the following reactions: 

(1) An alcoholic iodide is heated with zinc to 150° (Frank- 
land). In this reaction a compound of the radical with zinc is 
first formed, and this is decomposed by an excess of the iodide. 

(a) 2 Zn 4- 2 C^H J = Zn(C.,H,)2 + ZnT^ 
(6) Zn(C,HJ, + 2 CH,I =2 C,H,, 4 Znl^. 

(2) Sodium acts in a similar way to zinc, but much more 
readily and at a tower temperature (Wurtz). If a mixture of 
two iodides, such as those of ethyl and amyl, be employed, the 
following reaction takes place : 

C,H,I + C.H,^! + 2Na = C.U^^A- 2NaI. 

At the same time the hydrocarbons butane (diethyl) and tetra- 
methylhexane (diamyl), Cj^IIgQ, are formed by reactions which 
are readily understood. 

These, however, are not the sole products either of this or of 
Frankland's reaction, inasmuch as a small portion of the paraffins 
decompose into lower members of the paraffin group and into 
the hydrocarbons of the series C„Hon. Thus by the action of 
zinc upon ethyl iodide, not only do we obtain butane, but also 
ethane and ethylene : 

The higher members of the series are especially apt to 
undergo such decompositions. Thoq^e and Young ^ found that 
when solid "paraffin'' is repeatedly distilled it yields liquid 
paraffins which, according to their boiling points, appear to be 
normal ones, the w^hole series, beginning with pentane and 
reaching up to C^^H^q, being present ; and at the same time the 
corresponding hydrocarbons of the series CnHon are produced. 

(3) The paraffins may be obtained synthetically by the 
electrolysis of the fatty acids (Kolbc). The decomposition 
which here occurs will be fully described under the particular 
acids. The first paraffin obtained in this way was tetramethyl- 
butane or dibutyl, formed from valerianic acid : 

2C,Hy.C00H = CgHig-f 2CO,+ H2. 

* Chcm, S(K', Jtnirn, xxvi. 2C0. 



138 PREPARATION OF THE PARAFFINS. 



(4) When an alcoholic iodide is heated with zinc and water 
to 150° a paraffin is produced, whose molecule contains the 
same number of carbon atoms as the iodide : 

2 CgHjI + 2 Zn + 2H,0 = 20 Jl^ + Znlg + Zn(0H)2. 

In this case also, the zinc compound of the alcohol radical is 
first formed, and this is at once decomposed in contact with 
wat<5r. Hence pure paraffins can be readily obtained by bringing 
such a zinc compound into contact with water, which acts upon 
it with great energy : 

Zn(C,H,), + 2H,0 = Zn(OH), + 2 C^H^ 

Certain of the other metallic compounds of the alcohol 
radicals are decomposed by w\ater in the same way, others, 
again, such as the mercury compounds, do not act on water, but 
are easily attacked by acids : 

Hg{C,H,), + HCl = C,H, + Hg(C,H,)CI. 

(5) Nascent hydrogen eflFects an inverse substitution in the 
iodides. Thus if hexyl iodide be brought in contact with zinc 
and hydrochloric acid, hexane is funned : 

C^a^i J + Ho = CqH.^^ + HI. 

The following reactions, however, take place at the same 
time 

(a) 2 C,H,3l + Zn = O.oH,, + Znl, 

{hj CjoHjg = CoHj^ -I- CgHig, 

thus giving rise to small quantities of hexylene and dodecane. 

(6) When an alcoholic iodide is heated with an excess of 
hydriodic acid a piraffin is formed together with free iodine. 
As hydrio<lic acid ooiiverts all the alcohols, even those of the 
polyvalent radicals, into io<lides, the alcohols can be readily 
converted into ]>araffins. Thus when mannitol is heated with 
hydriodic acid the following reactions occur : 

(«) C.H,(OH)« + 1 1 HI = C„H„I + 6 H,0 + 5 I, 
(i) QHi,I + HI = C.H„+Iy 

Bcrtholot ^ has indeed shown that when a large excess of con- 
centrated hydrio<lic a<*id is employed, and the mixture exposed 

1 A»n, Chwi. Phys, [4] xx. r.92. 



FORMATION OF THE PARAFFINS. 139 



to a high temperature, ahiiost every carbon compound can be 
converted into a paraffin or a mixture of these substances. 
Thus, for example, butyric acid and succinic acid treated in 
this way yield butane : 

(a) C.HgO^ + G HI = C.Hjo + 2 HgO + 3 1, 
(6) C,H,0, + 1 2 HI = C,H,, + 4 HgO + 6 1,. 

and aniline by this treatment yields hexane : 

CcHyN + llHI = CcH,, + NH,I + 5Ij. 

« 

Wood, coal, and even charcoal thus treated yield mixtures of 
paraffins. Graphite, on the other hand, remains unchanged. 

As free iodine may, in these cases, give rise to complications, it 
is advisable to add amorphous phosphorus in order to prevent 
the liberation of iodine. 

(7) Paraffins are likewise formed when the fatty acids or acids 
of the series CnHoii-oO^ are heated with alkalis. Acetic acid 
thus treated yields methane : 

CH3.CO.ONa H- HONa = CH, + CO(ONa),, 

whilst by heating suberic acid with baryta hexane is obtained: 

CflH^gCCO^H). + ^Ba(0H)2 = C^H,^ + 2BaC03 + 2,11,0. 

These reactions are, however, usually not simple ones, a larger 
or smaller quantity of bye-products being at the same time 
formed. 

93 The hydrocarbons obtained by dissolving cast-iron in acids 
also contiiin piraffins. By dissolving a manganiferous spiegel- 
iron in dilute sulphuric acid, Cloez obtained a lu^uid in which 
the series of paraffins from decane, C^oH.22* ^ hecdecane, Cj^Hj^, 
were contained.^ 

Paraffins are also formed by the direct distillation of wood, 
coal, bituminous shale, fatty oils, resins, animal matter, and other 
organic substances. It has already been stated that Reichen- 
bach was the first to obtain the solid members of the series. 
In tliis way he also obtained a mixture of the lower members, 
which are usually liquids. To this mixture he gave the name 
of cupion (ei, good, and ttcov, fat). He observed that these 
liquids are not attacked by sulphuric or nitric acid, or even by 
potassium or the alkalis.^ Frankland' then noticed that the 

^ C(mpi, Rend. Ixxxv. 100.3. • lb. Ixxiv, 57. 

' Ana, Chem. Pharnu xiii. 217. 



140 OCCUURENX& OF PARAFFIXft 

lower boiling portion of this prolxibly consisted of |>eutaQe 
(amyl hydride). 

Liquid paraffins occur together with solid products in very 
large quantities in the products of the distillation of coal or 
of bituminous shales containing largo quantities of hydrogen, 
such as Boghead cannel (Greville Williams), and cannel coal 
(Schorlemmer). From their boiling-points, these all appear 
to belong to the normal series of paraffins, and in this 
respect resemble those obtained by the distillation of the 
lime-soap obtained from Menhaden oil (the oil of the fish Alosa 
Menhaden). * 

Paraffins also occur in nature. Several are contained in the 
different kinds of petroleum. That which is now obtained in 
such enormous quantity from Pennsylvania consists almost ex- 
clusively of normal paraffins, containing, however, together with 
these, small quantities of isomerides, whose constitution has not 
yet been ascertained, as well as other series of hy<lrocarbons, 
such as the groups CnHsn, CnHon-o, and probably also groups 
lying between these.^ 

Petroleum almost always contains solid paraffin. Canadian 
petroleum is especially rich in these solid products, as is also 
that obtained by the distillation of Boghead cannel. Indeed, 
this latter substance contiins a portion of the solid paraffins 
already formed, as may be shown by extracting it from the 
mineral vith ether. "^ 

Similar compounds occur as minerals in the coal measures as 
well as in the deposits of brown-coal and bituminous shale. 
These are known under the names of oajkerite, hatchettite, 
mineral tallow, mineral wax, i^'c. A solid paraffin, which pro- 
bably possesses the fornmla t'l^Hg^, is contained in the oil of 
roses, and se^xirates out in the crystalline form on cooling 
the oil. 

A very remarkable occurrence of nonnal heptane has lately 
been o])S<'rved by Thorpe* in the resin from a Califomian pine 
{Pinus sahinianu). This will be described more specially 
hen 'after. 

94 Appliratiini of rarajjins, Paraflin as obtiiined on the 

* Warrr-ii nml StonT, Mem. Jmcr. Acad. ix. 208. 

' SchorlcmiinT, yViiV. Tntns. 1871, vol. clxii. \mTt i. p. Ill ; Chrm, St^\ 
Journ, [2J, viii. *J16 ; Warrrii, Sillinunis Amrr. Jtwnt. xl. b9, 21C ; Pelouze nml 
C'aliourfl, Comjtf, lit lul. liv. I'JJl ; Ann. Chiin, Phys. [4J, i. 5. 

' IJoll»'y, A'ut. f'hftn. Phnnu, txv. 61. 

* Cheui, .V'/r. Jvurii. 1671*. 



AFPLK^ATIONSOF PA1UFFIN3. Ul 



manufacturing scale is not chemically pure. The commercial 
products always consist of mixtures of paraffins, and frequently 
contain hydrocarbons belonging to other series. 

The tar obtained by the distillation of bituminous shale. 
Boghead caunel, brown-coal or peat, is worked up for a variety 
of products, of which the most .important are ; (1) naphtha, 
chiefly used as a solvent ; (2) illuminating .ojls, known in com- 
merce as kerosene, photogene, paraffin-oil, solar oil, mineral 
sperm-oil, &c. ; (3) lubricating oils; and (4) solid paraffins, used 
for candle-making, &c. 

In order to obtain these several products, the crude oil, 
after it has been separated from the watery products of distil- 
lation, is distilled a second time, when coke jremains behind. 
The distillate is then treated with caustic soda in order to 
remove phenol (carbolic acid) and similar bodies which im- 
part a disagreeable smell to the oil. Then it is brought 
in contact with sulphuric acid, which takes up certain basic 
compounds whi«h also have a disagreeable odour, and at the 
same time decomposes other bodies which impart a dark 
colour to the oil. It is then washed with water and dilute 
soda-lye and rectified. The first product which comes over 
is the naphtha, the second distillate is the illuminating 
oil, and after this comes the portion which is employed 
either alone or mixed with other suitable oils for lubricating 
purposes. As soon as the distillate begins i)artially to solidify, 
the receiver is changed, the solid portions being allowed to 
separate out in a cool situation as long as they will crystallise. 
The liquid is then drawn off and used as a lubricant, and the 
solid mjiss freed from the adherent liquid, dried in a centrifugal 
sieve, and then pressed in hair mats placed between iron plates 
heated to between 35"* and 40°. The solid mass is then melted 
and heated to laC, when it is mixed with 2 per cent, of sul- 
phuric acid in order to decompose all adherent impurities. It 
is next washed with hot water, and lastly crystallised from 
solution in the higher boiling portions of the naphtha. The 
mother-liquor is poured off from the crystals, and any adherent 
mother-liquor removed from the fused mass by treatment with 
superheated steam. The solid paraffin thus obtained is w^hite 
and oilourless. As it is a mixture of different compounds, the 
melting-point of the different kinds varies between 40'' and G0^ 
When warmed in the air at a temperature above 120°, it begins 
to evajx»rato, and at the same time absorbs oxygen, and becomes 



142 OCCURRENCE OF PARAFFINS. 



yellow. When the mass is extracted with alcohol, the unaltered 
paraffin dissolves, a soft brown elastic mass remaining behind.* 

Solid paraffin is also obtained in large quantities from the 
impure naturally occurring ozokerite or mineral wax. This is 
found at Borislav, in Gallicia, and elsewhere, in the form of a 
yellow solid of the hardness of common beeswax, which is 
purified by a process similar to that just described. 

Solid paraffin is chiefly used for the manufacture of candles. 
It is also used in chemical works and laboratories in place of 
oil for obtaining constant high temperatures, and for the purpose 
of rendering caoutchouc joints tight. 

95 PetroUtcm (oleum petrcc), also known as rock-oil or 
naphtha. Herodotus states that a substance known as pis- 
acuspludtum was obtained from the island of Zante, and was used 
for the purpose of embalming. Plutarch mentions the occurrence 
of the burning oil at Ecbatana, and Dioscorides, as well as Pliny, 
state that the rock-oil from Agrigentum in Sicily was used for 
illuminating purposes. 

Other localities in which springs of rock-oil occur have been 
known for many centuries. These natural oils remained, how- 
ever, for a long time almost unused, only small quantities of 
the product coming into the market, and being chiefly employed 
either for medicinal purposes or as lubricants. These sub- 
stances were not introduced on the large scjile until the year 
1859, when the remarkable petroleum industry of the United 
States arose, and the demand thus aroused soon stimulated the 
production in other countries. 

Petroleum is an unpleasant-smelling substance which, accord- 
ing to its place of occurrence, is either a colourless or yellowish 
liquid, usually possessing a bluish lustre, or a bn)wn or bltu'k 
semi-solid buttery mass, gradually approaching in appearance 
the various minerals known as mineral-pitch, asphalt, or mineral 
resin, which have been formed either by the volatilization of 
the liquid hydrocarbons or by their gradual oxidation. The 
different kinds of petroleum are all mixtures of a number of 
hydrocarbons occurring in varying pro|x^rtions. 

Petroleum is found in almost all the geological formations from 
the oldest up to the most recent of the stratified rocks. The 
oil-region of Pennsylvania is a narrow band about GO miles 
in length, lying between Pittsburg and Lake Erie. It occurs, 

^ Bolley, Schictiz, PoiyL Zcilsch. xiii. 65. 



ORIGIN OF PETROLKUM. 143 

like the Canadian deposits, in the Devonian formation.^ These 
latter extend over a large area, lying between Lake Erie and 
the River Hudson. The deposits in Ohio, Virginia, Tennessee, 
Kentucky, and California are of less magnitude. 

A variety of theories have been broached to explain the 
origin of the petroleum springs.^ That which is generally 
received is that petroleum is a product of decomposition 
of organised mateiial. On the other hand, Byasson* and 
Mendelejeflf* are of opinion that it is produced by the infil- 
tration of water into the interior of the earth, where, coming in 
contact with molten iron or other metals containing combined 
carbon, it forms petroleum exactly as a similar mixture of hydro- 
carbons is obtained by the solution of cast-iron in dilute acids. 
This hypothesis is rendered somewhat more probable by the 
observation made by Silvestri ^ of the occurrence of petroleum 
in certain lavas of Etna. This amounts to 1 per cent, of the 
solid lava, and consists partly of liquid products boiling from 
79"" to 400°, and partly of solid paraffins. 

In addition to the above-mentioned sources of petroleum, the 
following rock-oil springs are of importance. Those already 
mentioned, situated in the island of Zante ; those in the Crimea 
and the Caucasus, where at Baku, on the west shore of the 
Caspian, the sacred fire has burnt for an unknown period, and 
where, especially in summer, the springs are so powerful that 
a jet of oil issues to a height of 30 feet. Other well-known 
sources of petroleum occur in Persia, Burmah, India, China, in 
Trinidad, Barbadoes, &c. In Europe petroleum is also found 
in Italy, Gallicia, Bavaria, Hanover, Holstein, and Alsace. 

96 Hie Petroleum arid Paraffin Oil Manufacture took its rise in 
England about the year 1847, when a spring of dense petroleum, 
having a specific gravity of 9, was discovered in a coalmine at 
Alfreton, in Derbyshire, by Dr. Lyon Playfair, who communicated 
the fact to Mr. James Young and Mr. Meldrum. In conjunction 
with Mr. Meldrum, Mr. Young succeeded in rendering this 
available for a period of two or three years. After this period 
the spring was exhausted, and it became necessary to seek for a 
source from which a material similar to petroleum could be ob- 
tained. Common coal, such as that from which Beichenbach 



* Die PetroleumiTuiustrU KordamerUcas^ "Wicn, 1877. 
- Neucs JIandwdrterbuchf iii 39. 

» MonU, Scientif, 1876, 1077. * Piivue Scientif. 1877, 409. 

* Qaz, Chinu Ital. 1877, 1 ; Zeitsch, Kryst, L 402. 



144 AMKKICAN OIL-WELLS. 



first obtaiaed parafiin oil and paraffin, yields, however, so small 
an amount of tar products on distillation that it was impossible 
to employ this as a source of petroleum. Mr. Binney found 
another natural source of petroleum in a peat bog at Down- 
holland, and he endeavoured, unsuccessfully, to obtain this 
substance artificially by the destructive distillation of the peat. 
Another material was, however, discovered, somewhat approxi- 
mating to coal, or intermediate between bituminous shale and 
what is. commonly known as coal, at Bathgate, in Scotland, and 
this was being introduced for gas-making under the name of 
Boghead gas-coal just about the time when the exhaustion of the 
petroloum spring in Derbyshu*e caused Messrs. Biuney and Young 
to search for another source of paraffin for the preparation of 
lubricating and burning oils. After many trials with other 
materials Mr. Young, in 1850, became ac^iuainted with the 
Boghead or Torbane Hill mineral, and found that it yielded on 
distillation an unusually large amount of paraffin. He at onco 
obtained a patent (No. 13,292) for the manufacture of oils from 
it, and thus founded the well-known works at Bathgate, which 
exist to the present day, for the preparation of paraffin oils and 
solid paraffin. 

97 Amcricayi OU-urlls. The occurrence of jxitrolcum in Penn- 
sylvania had lonj; been known, and the Indians were in the 
habit of employing it as a medicine for outward application. 
At the beginning of this century a gallon of this rock-oil cost 
upwards of £4, but in the year 1843 its i)rico had sunk to five 
shillings. Tiio first j)roposition to employ boro-holes fur obtiiin- 
ing a supply of the petroleum was made by G. H. Bissel, and 
ontlie 27th August, 185J), Mr. Drake oj)oned the first bore-hole 
at Titusvillo. This gave a daily yield of 880 gallons of oil. 
Sh(»rtlv afterwards the oil mania broke (»ut. and this reached its 

4 

maximum in the year 1801, when Funk bored the first flowin.^^- 
well, which yielded daily about 10, QUO gallons, and shortly after- 
wards another spring which yielded over 100,000 gallons jkt diem. 
Since this time a large number of ecjually fruitful wells have 
bei*n l)ored. 

Crude petroleum was first worked u]) for illuminating oil, 
which, as soon as improved lamps for burning petroleum were 
introduced, became widely used throughout Europe, thus giving 
rise to the petroleum industry in Crtna<la, Gallicia, and other 
places. The oil wells of r«nn.<ylvania yield annually over twenty 
million of gallons of oil. 



AMERICAN OIL WKLLa 145 



The oil is accompanied by a considerable quantity of gaseous 
products. These chiefly consist of hydrogen, marsh-gas, and 
ethane.* The amount of the gas thus evolved is in some 
localities so large that it is used not only at the spot where 
it issues for heating and illuminating purposes, but is carried 
in pipes for very considerable distances serving to heat boilers, 
blast-furnaces and puddling-funiaces, &c. 

The following description from the pen of Professor Lawrence 
Smith * gives some idea of the size of these gas-springs : — " The 
principal oil-wells are found in Butler county, Pennsylvania, lat, 
40"* 30', long. 80^ Wells of minor importance are also found 
in the neighbouring counties. The two most productive wells 
are those of Bums and Delameter, about 30 miles from Pitts- 
burg. Their depth is about 1,600 feet, for they are bored down 
to the fourth layer of sand. The Burns well has never given 
oil, but the one at Delameter was a petroleum well of 1,600 
liters; it now gives gas at such a pressure that plummet-lines 
weighing 800 kilos can be drawn out of it with the hand. The 
Delameter wfcU is situated in a valley surrounded by mountains, 
and furnishes heat and light to the whole neighbourhood. A 
large number of pipes diverge from this well ; one conducts the 
gas direct to the cylinder of an engine which, with this pressure 
alone, acquires an enormous speed. Another pipe feeds a flame 
capable of reducing as much iron-ore as half the blast-furnaces 
of Pittsburg can put out in a day. Twenty yards further on is the 
mainpipe of the wells ; from a pipe 3 inches in diameter issues 
a flame 40 feet high, the noise of which shakes the hilL\ For 
a distance of 50 feet round the earth is burnt up; but further 
off the vegetation is tropical, and enjoys a perpetual summer. 
On a calm night the noise can be heard at a distance of 15 
miles; at 4 miles the noise is like that of a train passing near, 
whilst close by it resembles that of a thousaiid locomotives 
blowing off steam. At the distance of a furloug the noise is 
like the continued roar of artillery, the human voice can scarcely 
be heard, and the flame reaches a height of 70 feet. In winter 
the surrounding mountains are covered with snow, but on 
two acres around the well the grass is green, except in the 
immediate neighbourhood, where the soil resembles lava." 

The oil, which either flows from the wells or is pumped up, 
also contains gaseous parafiins in solution, especially ethane, 

' Sadder, Amcrimn Clicmist^ 187C, p. 93 ; Foiiqiu', Ompf. Itcnd. Ixvii. 1015. 
a Joum, CJiem, Soc. 1879, i. j). 287. 

VOL. in. L 



146 THE PAHAFFINS. 



propane, and butane.' These gases, which are given off in the 
distillation of the crude oil, are again condensed by pressure, 
and the liquor obtained, consisting mainly of butane, is termed 
cymogene, and is employed for the production of artificial cold. 
The products boiling at about 18** are known as rhigolene, and it 
has been suggested to employ this as an anaesthetic agent, 
• The products boiling up to about 170** are distinguished 
as gazoline, naphtha, and benzine, ligroin, or petroleum-spirit. 
These are partly used for illuminating purposes, specially con- 
structed lamps being employed for burning them ; or they are 
used for saturating air or hydrogen, the mixture of vapour 
and gas being burnt in an ordinary gas-burner. Another use of 
petroleum-spirit is as a substitute for turpentine, as a solvent 
for india-rubber, and for oil in the woollen manufacture, &c. 

The oil boiling above 170*" is termed "standard kerosene," 
or "mineral sperm" oil, having a "flashing-point" of 150*" F., 
and is used for burning in the ordinary paraffin lamps. 

According to the Act passed in 1871 " for the safe keeping of 
petroleum," 2 no oil can be sold which evolves combustible 
vapour at a temperature of 100° F, (37°'8 C). 

At the request of the Government, Professor Abel has lately 
investigated the various methods in use for determining the 
"flashing-point " of petroleum. He finds these to yield unsatis- 
factory results, and he proposed a new system of testing which 
has now been adopted by Government, and embodied in an Act of 
Parliament. A standard apparatus for this purpose is placed in 
charge of the Weights and Measures Office, and every apparatus 
has to be stamped and tested so as to be identified as a legal 
apparatus. The flashing-point of 73° as furnished by the new 
test is equivalent to the minimum flashing-point of 100** as 
obtained by the older methods. 

Prepdraiion of the Normal Paraffins from Petroleum, It has 
already been mentioned that Pennsylvanian petroleum, as well 
as the lighter oils obtained from Boghead coal and canncl, 
contain the normal paraffins. In order to obtain these in the 
pure state, Grevillo Williams decomposes the mixtures which 
are contained in the petroleum by carefully treating the oil 
with concentrated nitric acid, when the other hydrocarbons, &c., 
are partly oxidised and partly converted into heavy volatile 
nitro-compounds. As, however, concentrated nitric acid act« 
very violently on the mixture, and sometimes m.iy even cause 

» Ronalds, Joum. Chcm. Soc, xviii. 61. • 34 & 35 Vi<t. o. 105. 



FRACTIONAL DISTILLATION. 147 

the igDition of the oil, it is better first to shake the oil re- 
peatedly with concentrated sulphuric acid until the substance 
is no longer coloured, and then to act on the residue with con- 
centrated nitric acid, or with a mixture of the commercial acid 
and sulphuric acid. When no further action takes place, the 
oil is separated from the acid, washed with water and caustic 
soda solution, and dried over solid caustic potash. It is then 
distilled in order to separate it from any adherent nitro-com- 
pounds, and repeatedly rectified over sodium, when it may be 
separated into its constituents by repeated fractional distillation. 
As this process is very often employed for the separation and 
purification of volatile bodies, we shall here shortly describe it. 



FRACTIONAL DISTILLATION. 

98 When a mixture of two liquids whose boiling-points do 
not lie close together is subjected to distillation, a large portion 
of the more volatile body comes over at the beginning; 
but the boiling-point gradually rises, and more and more of 
the vapour of the less volatile mixes with that of the more 
volatile compound. It is only when the difference between 
the boiling-points of the two bodies is very considerable 
that it is possible to effect an almost complete separation 
by one distillation. In such a case, when the operation is 
carried on very slowly, the more volatile body distils at a nearly 
constant temperature ; and as soon as all has passed over, the 
thermometer rises rapidly to the boiling-point of the less volatile 
compound. But in most instances it is impossible to obtain 
even an approximate separation by one distillation only. By 
collecting separately the portions distilling between certain 
intervals of temperature, say between each 5" or 10°, the first 
will consist chiefly of the lower boiling body, and the last of 
the less volatile substance, whilst the composition of the greater 
portion, boiling between those two points, remains very similar 
to that of the original mixture. 

The following example shows how imperfectly even bodies 
whose boiling-points do not lie close together can be separated 
by one distillation. A mixture of 100 grams of ethyl alcohol 
(boiling-point 78***4) and 100 grams of amyl alcohol (boiling- 
point 132'') was distilled from a long-nockcd flask, and the 

L 2 



148 



FRACTIONAL DISTILLATION. 



distillate collected in seven fractions, the composition of which 
was found by optical analysis to be as follows : 



Boiling-point 


80*-«l' 


90'-100" 


lOO'-llO' 


iio'-iao* 


120*-130' 


130'-131' 


131M32" 


Wei^t of fraction 


*7 


45 

82 
18 


25 


14 

521 
47-9 


18 


11 


36 


Per cent, of ethyl alcohol . 
Per cent, of auiyl alcohol . 


88 1 
11-9 


615 
38-5 


lS-4 
SI 6 


45 
95-5 


0-2 
99-8 




100-0 


100 


100.0 


100 


100-0 


1000 


100^ 



Four grams of pure amyl alcohol remained in the flask. 

It is not difficult to explain why, in such a distillation, 
the less volatile body distils so much below its boiling-point. 
As is well-known, all volatile bodies evaporate below their 
boiling-points, and this takes place with the greater facility the 
higher the tension of the vapour ard the quicker the surround- 
ing atmosphere is changed. Now these conditions are fulfilled 
on boiling a mixture of two liquids ; the vapour of the lower 
boiling body carries that of the less volatile substance with it 
on passing through the mixture, and being quickly condensed, 
a new atmosphere is constantly formed. 

In ordinary cases such mixtures contain more than two com- 
pounds. Thus the so-called fusel-oil is a mixture of several 
homologous alcohols. In order to isolate from such mixtures 
tolerably pure compounds, the diflferent fractions obtained in 
the first distillation must again be submitted to the same 
operation, and those portions which distil between the same 
intervals of temperature collected separately, and this process 
repeated until bodies with a nearly constant boiling-point have 
been obtained. A complete separation, however, cannot be 
effected in this way; since the substances obtained by this 
method, although they may have a constant boiling-point, are 
never j)orfectly pure, and require to be afterwards treated by 
some different ]>roce88 to ensure their perfect purity. 

99 The apparatus used for the purpose of fractional distilla- 
tion in the laboratory is that suggested by Wiirtz and shown 
in Fig. 54. Tlie flask A contains the boiling mixture ; the 
vajKiurs of the hydrocarbons i)ass into the bulb-tube r, in which 
a thermometer is ])laced, and the les? volatile portions are here 
jxirtly condensed as the vapour comes in contact with a large 
surface cooled by the atmosphere. The vapour which is not 



WUBTZS TUBES. J49 

condensed passes next into the Liebig's condenser, c, surruunded 
by cold water, and from this the liquid can be collected in various 
fractions in the receiver B. 

Linneniann ' has improved on this methoil, inasmuch us he 
places cups of platinum gauze in the upright tube through 
which the vapour passes (Figs. 55 and 56). The liquid con- 
denses on these, and falls back through the meshes. The vapours 
arc tlius washed by tlie liquid, and come in contact with a column 
of liquid whose temperature is always lower than that of the 
mass of the liquid in the flask. When this apparatus is in 




use, the tube and bulbs gradually become tilled with liquid and 
all the vapour is condensed. It is therefore necessary to remove 
the flame from time to time in order that the liquid may flow 
back again. In this way the process of distillation is rendered 
slower, and an improvement has been introduced by the attach- 
ment of aide-tubes to the bulbs (Figs. 57 and 58), down which 
the condensed liquid flows regularly back into the flask. 

100 Ad apparatus somewhat different from this has been em- 
ployed by Warren * in the fractional distillation of tar-oils and 



1. CAcm. Fhamt. cll. 195. 



' Aim. Chtm. Fharm. Suppl. i 



FRACTIONAL DISTILLATION. 



petroleum B. This permits a complete control over the temperature 
of the vapour, accomplished by &a air-bath (a a, Fig. 59), roood 



.-^ 




which a spiral tube is placed, connected with thob«.iling-flask. 
The tempemture of this ftir-l»th is regulat«d by a lamp The 



WARREN'S APPAKATUS. 151 

liquid used for heating the air-bath may be either water, uil, or 
fusible metal, and into this the thermometer (i) is placed. The 
boiliDg of the liquid and the temperature of the bath are SO 
regulated that the liquid boila somewhat rapidly. In distil- 
ling petroleum the difference in temperature between the boil* 
ing liquid and the air-bath was, to begin with, about S5° 
or even more. This difference became gradually smaller as 
the various fractions were redistilled, until at last it almost 




Fio. 



disappeared. An apparatus of a .timilar kind, but on a lai^er 
scale, as used by Warren, is shown in Fig. 00. 

loi Even the approximate separation of volatile substances 
cannot, however, always be carried out by fractional distillation, 
even when the boiling-points are considerably removed from 
one another. Thus, for example, if a mixture of aiiiline boiling 
at 182° and watc-r be distilled, the aniline distils over firat In 
such a case the boiling-point of the mixture is frequently lower 
than that of the more volatile bwly. Pierre and Puchot ' found 
' Cv,.i2-i- Hcnd. hxiii. .iHn, 788. 



FKACriONAL UISTILLATIOS. 




DISTILLATION OF MIXTURES. 163 



that a mixture of water and of amyl alcohol, which boils at 
132*', begins to boil at 96*^, and the distillate contains 2 volumes 
of water to 3 of amyl alcohol. Similar observations have been 
made with other mixtures. 

Wanklyn ^ has shown that, when a mixture of equal parts by 
weight of two liquids of different boiling-points is distilled, the 
quantity of each constituent in the distillate is proportional to 
the product of its vapour density and vapour tension at the 
temperature of ebullition of the fraction. Hence, if the vapour 
tensions and vapour densities of the two liquids are proportional, 
the mixture will distil unchanged. Berthelot has confirmed this 
conclusion. He found that a mixture of 90 '9 parts of carbon 
disulphide, which boils at 4G°, and 91 parts of ethyl alcohol, 
boiling at 78°*4, possesses a constant boiling-point of 78°'4, 
and distils without undergoing any alteration in composition. 
Thorpe ^ has added another example in corroboration of this 
conclusion, as he observed that, when a mixture of equal volumes 
of carbon tetrachloride, boiling at 76°*6, and methyl alcohol, 
boiling at 65°*2, is distilled, 4G%5 per cent, of the whole boils 
between 55**'6 and 59°, that is to say, nearly 10° lower than the 
boiling-point of the most volatile constituent. The distillate 
contains, to 1 part of methyl alcohol, 3*61 parts of tetrachloride 
of carbon, and by multiplying the vapour tensions of the two 
liquids at 55°*7 by their vapour densities almost exactly the 
same relation is obtained : 

372-4 X 7G-69 _^^rj 
487-4 X 15 97 "" ^'^^• 

When the residue is distilled further, almost pure tetra- 
chloride of carbon comes over first, and afterwards pure methyl 
alcohol. 

A striking lecture experiment, illustrating the effect of 
the admixture of the two liquids, is to fill three barometer 
tubes with mercury and to pass up into the first a few drops of 
methyl alcohol, into the second a few drops of carbon tetra- 
chloride, and into the third a small quantity of a mixture of 
methyl alcohol and carbon tetmchloride in the proportion of 
3 cbc. of the former to 5 cbc. of the latter. In the first tube 
the mercury will be depressed about 80 mm., in the second 
70 mm., whilst in the third it will sink through 130 mm. 
(Thorpe). 

J Phil. Marj. [4] xlv. 129. - Jnaru, Chcm. SW. 1879, 514. 



I 



164 COMPOUNDS OF MONAD ALCOHOL RADICALS 



THE COMPOUNDS OF THE MONAD ALCOHOL 

RADICALS. 

CnH2n + 1. 

102 In the following chapter will be found a short description 
of the chief fSeonilies of the above compounds, arranged in the order 
in which their chemical history will be considered in the sequel. 

These compounds are derived from the paraffins by the 
substitution of one atom of hydrogen by other atoms or groups 
of atoms. They may, therefore, be regarded as compounds of 
monad radicals, to which the name of the alcohol radicals has 
been given, because the alcohols were the first compounds of 
these bodies which were studied, and even to the present day 
these bodies are employed as the point of departure for the 
preparation of the other compounds. 

The Alcohols are hydroxides, and in many cases exhibit 
analogous properties to the hydroxides of the metals. Hence 
Liebig, when he established the radical theory, compared ethyl 
alcohol to caustic potash. The latter substance was then sup- 
posed to be a compound of potassium oxide with water, or 
hydrated potash, and alcohol was accordingly considered as the 
hydrate of ethyl oxide. According to the theory of types, it was 
considered as water, in which 1 atom of hydrogen is replaced by 
ethyl, but it may just as truly be considered to be ethane, in 
which 1 atom of hydrogen has been replaced by hydroxyl, or, 
in other words, it is formed by the union of two monad residues, 
ethyl, CjHj, and hydroxyl, OH. 

Ethereal Salts or Compound Ethers, The alcohols are con- 
verted by the action of acids into compound ethers, the alcohol 
radical replacing, either partially or wholly, the hydrogen of the 
acid: 

Ethyl chloride. 

(«) C,Hj.OH + HCl =CjHjCl +HA 

Kthyl nitrate. 

(6) CjHj.OH + HO.NOs = CjEjCNO, +HjO. 

Hydrogen ethyl sulphate. 

(c) C,H,.OH + gg I SO, = 5,H,0 } S^* + ^«^ 

Other modes of formation of compound ethers^ may be 
mentioned : 



THE ALCX>HOLS AND ETHERS. 155 



(a) A silver salt is heated with an alcoholic iodide : 

Ag^COj + 2C2H,I = (G^B.,)fiO^ + 2 Agl. 

(6) Absolute alcohol is acted on by an acid chloride : 
POCI3 + 3HO.C2H5 = VOiOC^U,)^ + 3HC1. 
SiCl, + 4HO.C2H, = Si(OC,H,), + 4HC1. 

(c) A salt of the corresponding acid is distilled with a salt of 
ethyl — sulphuric acid, or other corresponding alcoholic sulphate : 

KCIO, + K(C2HJS0, = C2H,.C10, + K^SO,. 

The alcohols can again be obtained from the ethereal salts or 
compound ethers by heating them with an alkali, thus : 

C2H5O.NO2 + KOH = C2H5OH + KO.NO2. 

Haloid Ethers. The compounds of the alcohol radicals with 
the elements of the chlorine group are termed haloid ethers. 
These are formed in a variety of ways. Thus, for example, the 
chlorides and bromides are obtained by the action of the corre- 
sponding haloid elements on the paraffins, and also by the action 
of the corresponding phosphorus compounds on the alcohols : 

{a) C2H5.OH + PCI5 ^CgHjCl+POCla + HCl. 
(6) C2H5,OH + PBr5 = C2H5Br + POBr3 + HBr. 

When an excess of alcohol is present, the hydracid formed as 
well as the phosphoryl compound react upon it, the amount of 
the haloid ether being increased : 

SCgH.OH + POCI3 = 3C2H5CI + P0(0H)3. 

In this case, however, the free phosphoric acid acts upon 
another portion of the alcohol, and a phosphate is produced. 

In order to prepare the iodides, the alcohols are heated with 
concentrated hydriodic acid, or, better, they are treated directly 
with iodine and amorphous phosphorus : 

5C2H5OH + 51 + P = 5C2H5I + H3PO, + H2O. 

The alkalis usually act on the haloid ethers in a different 
way, and instead of obtaining the alcohol, the hydracid is 
separated and an olefine formed. Hence, in this case, freshl 
precipitated moist silver oxide is usually employed, and this 
as if it were the hydroxide AgOH. 




166 COMPOUNDS OF MONAD ALCOHOL liADICALS. 



The alcohols may also be readily obtained from the haloid 
ethers by converting the latter into the ethereal salts of organic 
acids and then decomposing these by alkalis. The same end 
may likewise be attained by heating the haloid ethers with 
water under pressure : ' 

C.HjjCl + HjO = C^HgOH + HCl. 

This reaction serves as a striking example of the influence of 
mass, for whilst fuming hydrochloric acid easily converts butyl 
alcohol into the chloride and water, exactly the opposite reaction 
takes place in presence of a large quantity of water, inasmuch 
as a weak acid does not attack the alcohol. Hence it follows 
that, when an alcohol is heated with an acid, not in excess, a 
condition of e<iuilibrium is attained when the acid becomes so 
dilute that its action ceases. 

X03 Simple and Mixed Ethers are formed when the hydrogen 
of an alcoholic hydroxyl is replaced by an alcohol radical. Hence 
these bodies are oxides of the radical, standing in the same 
relation to the alcohols as potassium oxide does to caustic potash. 
These bodies can be obtained by a variety of reactions : 
(1.) The alkali-metals dissolve in alcohols with evolution of 
hydrogen. Sodium and ethyl alcohol thus form sodium ethylate, 
CjHj.ONa, and if this be warmed with ethyl iodide, ethyl oxide 
or diethyl ether is obtained : 

Ethers which contain the same radical twice are termed 

simple ethers, whilst those which contain two different alcohol 

radicals are termed mixed ethers. If in the above reaction ethyl 

CH ) 
iodide be replaced by methyl iodide, methyl-ethyl ether, p xf f O, 

is obtained. 

(2.) Ethers are also formed when the alcohols are heated 
with concentrated sulphuric acid. In this case the alcoholic 
hydrogen sulphate is first formed, and this is decomposed by 
the excess of alcohol, as follows : 

The mixed etliers may also be obtiined in this way. Thus 

* Nifilcrist, Liebiga Ann, clxxxvi. 388 \ cxcvi. 349. 



MIXED ETHERS AND TUIO- ALCOHOLS. 167 



methyl-ethyl ether is ohtained hy heating hydrogen ethyl 
salphate with methyl alcohol. 

(3.) When an alcohol is heated with an iodide, an ether is also 
formed, and this occnrs when concentrated hydriodic acid is 
heated with an excess of alcohol, the following reactions taking 
place: 

(1) C,H„.OH + HI « C,Hi,I + HgO. 

(2) C,H,,I + C,H,,OH = (C,H J,0 + HI. 

A small quantity of hydriodic acid suffices to convert a large 
quantity of alcohol into ether. The reaction continues until 
a certain quantity of water is formed, when a condition of 
equilibrium is attained. 

Hydrosulphides and Sulphides. The hydrosulphides are also 
termed the thio^lcohoh, as they are obtained (1) from the 
alcohols by the substitution of sulphur for oxygen, thus by 
acting on the alcohols with phosphorus pentasulphide : 

SC^HgOH + P2S5 = oCgH^SH + Tfi,, 

Free phosphorus pentoxide is, of course, not formed, out the 
thio-phosphates, such as (02H5)2HP02S2 and (C2H5)3 POgSj. 

(2.) The hydrosulphides are also formed by the action of an 
alcoholic chloride on potassium hydrosulphide : 

CgHgCl + KSH = C,H,.SH 4- KCl. 

(S,) Also by heating a solution of the latter compound with 
potassium ethyl sulphate : 

KSH -f K(C2H,)S0, = C2H5.SH + K2SO,. 

The thio-alcohols are, like many volatile sulphur compounds, 
distinguished by their disagreeable smell. They stand in the 
same relation to common alcohol as sulphuretted hydrogen does 
to water, and resemble this compound inasmuch as they act as 
weak acids, and as one atom of hydrogen can easily be replaced 
by metals. Amongst these metallic compounds those with 
mercury are the most characteristic. They are formed when a 
hydrosulphide is brought in contact with mercuric oxide : 

2 C,H,SH + HgO = (C,H5S),Hg + H.O. 
In consequence of this relation the thio-alcohols have been 



158 COMPOUNDS OF MONAD ALCOHOL RADICALS. 

termed mercaptans (mercurium captaiis), and their metallic 
compounds vicrcaptides} 

The SuljMdcs or Thio-Ethers are always formed in the pre- 
paration of the mercaptans from the chlorides, the following 
reactions taking place: 

(1) C2H5SH + KSH = CgH^SK -f SHj. 

(2) C^H^SK + C,H,C1 = (C,H5)2S + KCl. 

SiUphine Compmirtds} The sulphides unite with the iodides 
and bromides of the alcohol radicals to form crystallisable salts 
such as triethylsulphine iodide, S(C2H.)3l. These substances 
are not attacked by alkalis, but when freshly precipitated 
hilver oxide is added to their aqueous solutions, the corre- 
sponding hydroxides are formed, such as triethylsulphine 
hydroxide, S(C2H5)30H. These latter are difficultly crystallis- 
able, they are deliquescent, and possess alkaline and caustic 
properties like caustic soda. They also resemble the alkaline 
hydroxides, inasmuch as they precipitate metallic salts, expel 
ammonia from its compounds, and form, with acids, neutral salts, 
amongst which the chlorides unite with platinum chloride 
to form soluble double salts, such as [S(C2H5)3C1]2 + PtCl^. 

104 Sidphonic Acids. These acids are easily formed by oxi- 
dation of the mercaptans and other sulpho-compounds of the 
alcohol-radicals : 

^[ercaptan. Ethylsulphonic acid. 

C2H5.SH + 30 = C2H,.S02.0H. 

They possess the same composition as the corresponding acid 
sulphites of the alcohol radicals, which, however, are not known 
in the free state, as they decompose with extreme ease, whilst 
the sulplionic acids are very stable and powerful acids. They 
may be heated pretty strongly without decomposition, are not 
altered by boiling caustic alkalis, and only oxidised by nitric 
acid with difficulty, forming the acid sulphates. 

The sulphonates are also formed when an iodide is brought 
in contact with a solution of a normal sulphite : ^ 

C,H,I + SO3 I J^ = S0o| ^2^5 + KI. 

• Zcine asimmed the existence in the«e bodies of the radical CoHsS, to which 
he giive the name of mercnptum (mcrcurio a^itum). See I^rzvlius, JeUiresbcr, 
xiv. 334. 

• V, Ot'frlo, Ann. Chrm. Pharm, cxxvii. 370; cxxxii. 82. 

• StDTkcr, ^)m. Chrm, Phnrm. cxlviii. 90; Hemilian, 16. rlxviii. 185. 



COMPOUND AMMONIAS. 150 



Phosphorus pen ta chloride coDverts them into sulphonic chlorides : 

SO2 { g^^^ + PCI, = SO. I g|^5 + KCl + POCI3. 

And if this latter compound he treated with sodium ethylate 
the ethyl-ether of ethylsulphonic acid is produced : 

SO2 { §"^ -h NaOC,H. = SO, I g|?|^ + NaCL 

This ether is isomeric with ethyl sulphite, which is formed by 
the action of thionyl chloride on ethyl alcohol : 

SO I g{ + 2HOC2H, = SO I ^^2^6 4. 2HC1. 
Cold caustic potash converts the latter compound into alcohol 

r oc H 

and potassium ethyl sulphite, SO -I ^^ ^' which is isomeric 

with potassium ethyl sulphonate, from which it differs, inasmuch 
as its aqueous solution is easily decomposed with formation of 
hydrogen-potassium sulphite and alcohol. The rational con- 
stitution of this compound is not known. The easy conversion 
of mercaptan into sulphonic acid renders it very probable that 
in the latter the alcohol radical is in direct linking with sulphur. 
The alcohol radicals also form compounds with selenium and 
tellurium, the more important of which will be hereafter 
described. 

X05 The Compound Am fnonids or Amities are formed by heat- 
ing the haloid ethers, or the nitrates of the alcohol radicalsy 
with ammonia under pressure, when the following consecutive 
reactions take place : 

Primary Monamines. 

(1) CH.Cl + N-^H=N.^H + HCl. 

(H (K 



.Secondary Mouamiiies, 



ran, (C^Hj 

2) C,H,C1 + N -.' H' = N -^ C»H. + HCl. 

(h jrf 



Tertiary Monamines. 



(:5) CJI/'l + N -j C;h; = N-«( C4H6+HCI. 



no 1 2 U 

H (C,H, 



ICO COMPOUNDS OF MONAD ALCOHOL RADICALS. 



The amines containing the lower members of the series of 
alcohol radicals are gaseous at the ordinary temperature ; the 
higher ones are mostly liquids. They possess a peculiar 
ammoniacal smell, but generally this is accompanied by a fish- 
like odour. They precipitate many metallic salts, and combine 
directly with acids to form crystallisable compounds. Their 
chlorides unite with platinum chloride, like sal-ammoniac, 
whilst their sulphates yield alums with aluminium sulphate. 

The three groups into which they may bo divided are 
distinguished by the following reactions. 

(1.) The primary amines are converted into alcohols by means 
of nitrous acid. If a solution of hydrochloride of ethylamine 
be warmed with silver nitrite, the following reaction takes place : 

HJNHO.NO ^^ 

(2.) The secondary amines under similar circumstances give 
rise to nitroso-products : 



C^H, ^ N + HO.NO C^H, V N + H,0. 



0«Hk ) CgH 

^N+ HO.NO C^H, ^ 
HJ NOj 



The nitroso-diethylanune thus obtained is again converted into 
diethylamine on heating with aqueous hydrochloric acid. 

(8.) The tertiary amiiics are not affected by nitrous acid. 
They combine readily with the iodides of the alcohol radicals, 
giving rise to an iodide of a compound ammonium, such as 
tetramethylammonium iodide, ?s(CH3)^I. These decompose, 
on heating, into the compounds from which they have been 
formed, just as sal-ammoniac dissociates into hydrochloric acid 
and ammonia. In both cases re-combination takes jJace on 
cooling ; and hence the compound ammonium iodides apjxjar 
to distil without decomposition. They «are not deconj posed by 
alkalis. Moist silver oxide converts them into liydroxides, 
which are non-volatile, crystalline, very soluble bodies analogous 
in properties to the caustic alkalis. Thus they destroy animal 
matter such as the skin, sjiponify fats, precipHate many metallic 
compounds, &c., and form crystallisable salts with acids. Their 
chlorides yield, with ]>hitinum chlori<lo, compounds analogous 
to ammonium-})latinum chloride, Jind their suljihates give rise 
to alums. 



HYDRAZINE COMPOUNDS. 16f 



It has alreaxly been stated that frequent cases of isomerism 
occur amongst the amines. Thus, for instance, the hydrogen 
atoms in ammonia may be replaced by one, two, or three 
radicals, and thus a vanety of isomeric compounds result, and, 
by the above reactions, it is easy to distinguish whether we 
have to do with a primary, secondary, or tertiary compound, 
Tlie simplest case in which isomerism can occur is that of 
(1) propylamine, (2) methylethylamine, and (3) trimethylamine. 
If these bodies be treated with ethyl iodide as long as this 
substance produces any action, the following compounds aro 
formed : 

(1) Propyl triethylammonium iodide, N(C3H-.)(C2H.)3l. 

(2) Methyl triethylammonium iodide, N(CH3)(C2H5)3l. 

(3) Trimethylethylammonium iodide, N(CH3)3(C2Hg)I. 

It is only necessary to detennme the quantity of iodine con- 
tained in the body formed to ascertain which of these compounds 
is under examination. 

xo6 Hydrnzim Compounds, Just as the amines are derived 
from ammonia, NHg, so the hydrazines are derived from the as 
yet unknown body hydrazine or diamide, HgN — NH^. Com- 
pounds analogous to this are to be found in the liquid hydro- 
gen phosphide HgP — PHg, and in dimethylarsine (cacodyl), 
(CH3)^s - As(CH3)2. 

The hydrazme compounds as yet known are obtained by 
replacement of one or two atoms of hydrogen in hydrazine, 
H^N — NHg, by alcohol radicals. So far, only derivatives with 
one or with two alcohol radicals are known. In order to prepare 
mono-ethyl hydrazine, H^N — NH(C2H5), it is necessary to 
start from diethyl-urea, a secondary amine. This is treated 
with nitrous a<jid, giving rise to the nitroso-compound No. (1), 
and then this product is acted upon by nascent hydrogen, 
yielding the hydrazme-compouud No. (2) : 

Dicthylurea. (1). (-2). 

PH NH>^^0 >00 >C0 

1^,11,. IS n/ aH,.N -NO C,H-.N -NH.,. 

If the compound No. (2) be heated with alkalis or acids, it 
is decomposed like all ureas, yielding carbon dioxide, ethylamine, 
and ethyl hydrazine, as follows : 

VOL. in. u 



IGi COMPOUNDS OF MONAD ALCOHOL RADICALS. 



C4H..NH. H CjHj.NH., 

P H N >C^ + O = CO, 

^Hj.JN /jjjj^ jj (C,H5)H.N-NH,. 

Nitroso-amiues containing acid radicals, e.g. like 



So}^~^^' 



C.,H 
C 



give on reduction no corresponding hydrazines, but the amides 
are regenerated : 

Hydrazines containing two radicals, or Dihydrazines, are 
obtained by the reduction, with zinc dust and acetic acid, of 
the nitroso-dcrivatives of secondary amines : 

C.H.|N-NO + 2H, = g:S;}xN-NH, + H,0. 

The hydrazines are volatile liquids possessing an ammoniacai 
odour, and uniting with acids to form salts. 

Dihydrazincs unite with the iodides of the alcohol radicals, 
giving rise to azonium iodides, such, for instance, as triethyl- 
azonium iodide H2N.^(C2H5;3l. These are converted into 
powerfully alkaline hydroxides by means of moist silver oxide. 
Weak oxitlising agents resolve the dihydrazines into secondary 
amines with evolution of nitrogen, whilst stronger reagents 
give rise to Tetvazoncs, such as tetraethylazone, N^(C2H5)^ : 

H,N-N(0.,H,)o ^ o N-NCaH^), 

The tetrazones are non-volatile, oily, alkaline liquids possessing 
a garlic-like smell.^ 

X 07 Cya n id^a of the A hoJwl Eadicah. Those bodies are formed 
when an alcoholic iodide is heated with silver cyanide, or 
when a mixture of chloroform and an amine is treated with 
alcoholic potiish : 

CH3NH. + CHCI3 = CH3.NO 4- 3HC1. 

The compounds obtained in this way are usually termed 

» E. Fisolier, Liihigs Annalen, cxc. 67. Hid. rxcix. 281. 



CYANIDES OF THR ALCOHOL RADICALS. 1G3 



isocyanidcs or carbami?ies, in order to distinguish them from the 
isomeric compounds which had previously been prepared. They 
are poisonous liquids possessing a penetrating and highly 
unpleasant odour. Aqueous acids decompose them easily into 
formic acid and an amine : 

CH3NC + 2H2O - CHjNHj + COH.OH. 

When heated in closed glass tubes, they are converted into 
the isomeric nitrils, which bodies are also formed, together 
with small quantities of the carbamines, by heating an iodide 
with potassium cyanide, or by heating the latter compound 
with a hydrogen sulphate of an alcohol radical : 

NCK + ^ § } SO^ = NC.C2H5 + K.SO,. 

In this reaction a carbamine is doubtless first formed, and this 
is decomposed at the high temperature into a nitril. 

The pure nitrils possess a strong but not unpleasant smell. 
They are not changed by the action of dilute aqueous acids, 
but are converted into the fatty acids and ammonia in the 
presence either of strong aciucous mineral acids or of caustic 
potash. Thus methyl cyanide or acetonitril, when treated in 
this way, yields acetic acid : 

CH3.CN -f HCl + 2H2O = CH3.CO.OH + NH,a. 

On treatment with nascent hydrogen, the nitrils form amines : 

CH3.CN + 2H, = CH,.CHyNH,. 

And this reaction proves that in the nitrils the cyanogen is 
linked with the alcohol radical by the carbon atom, whilst in 
the carbamines it is nitrogen which connects these two, act- 
ing in this case, as in sal-ammoniac and similar bodies, as a 
pentad. All these compounds decompose on heating, with 
formation of bodies in which nitrogen is triad. The pentad 
nitrogen in carbamine is also converted on heating into the 
triad form, and hence we may assume that the compound first 
decomposes into cyanogen and the alcohol radical, and that these 
tben unite again : 

C=N-CH3 = N^C-»<r-CH3. 

Cyanates and Isoqfanates, The cyanates of the alcohol radicals 

M 2 



164 COMPOUNDS OF MONAD ALCOHOL RADICALS. 

are very unstable liquids, formed by the action of cyanogen 
chloride on a solution of sodium in an alcohol : 

NCCl + NaOC^Hj = NCOC^H, + NaCl. 

These bodies are decomposed in contact with the alkalis into 
an alcohol and a cyanate. They undergo polymerisation with 
extreme ease, and give rise to crystalline cyanuratcs. 

Isoq/anates, Carbimidcs, or Carbonylamines, are bodies isomeric 
with the cyanates. They were formerly believed to be the 
true cyanates. They are, however, distinguished from these 
by the fact that alkalis decompose them into carbon dioxide 
and an amine : 

^{ C(?' + ^^O = N j g^^s + CO,. 

This is the reaction by means of which the amines were dis- 
covered by Wurtz. Aqueous acids also decompose them in the 
same way. 

Ethyl carbimide is formed when potassium cyanate is dis- 
tilled with potassium ethyl sulphate. Probably ethyl cyanate is 
first produced, but this is converted by molecular rearrangement 
into ethyl carbimide. The other carbimides are formed in a 
similar way. They are obtained from the carbamines by oxida- 
tion with mercuric oxide, and are volatile liquids possessing a 
penetrating smell which causes a flow of tears, and they are 
easily converted into crystalline isocyanurates, 

io8 Co)i\i)oviul^Urcns or Carbamides. These bodies are de- 
rived from urea by the replacement of the whole or a portion 
of its hydrogen by alcohol radicals. They may be formed m 

{NH C H 
^TT* ^ ^ is ob- 
tained by the action of cyanic acid on ethylaniine, as also by 
treating ethyl carbimide with ammonia. If ethylamine bo 
employed instead of ammonia, a symmetrical diethyl-carbamido 
is fonned, which is also obtained by the decomposition of the 
carbimide with water: 

CO /N\ 

+ H.O = CO " + CO- 
CO \N/" 
^N-C.,H, \CM, 



r 



COMPOUITO UREAS. 165 



A compound isomeric with this may be prepared by acting 
with cyanic acid on diethylamine, whilst triethylcarbamide, 

^^ i N^OtI ^^' ^^ formed from diethylamine and ethyl car- 

bimide. The triamines do not undergo alteration when treated 
either with cyanic acid or with the carbimides, but the simple 
substituted carbamides are obtained by the action of diamines 
on carbonyl chloride. The compound ureas all unite with 
acids to form crystallisable salts. 

Uretluines or Carbamic Ethers. Carbamic acid, CO <f , is 

not known in the free state (VoL I. p. 646), and only a few of 
its inorganic salts have been prepared, but many of its com- 
pound ethers, or the urethanes, are well-defined substances. 
They may be prepared in several ways. Thus, if ethyl car- 
bonate be treated with aqueous ammonia, ethyl carbamate is 
formed : 

COJggl: + NH3 = C0{^H,^^ + HOAH, 

By the prolonged action of ammonia, ethyl-urethane is con- 
verted into alcohol and urea, whilst, on the other hand, if pure 
alcohol be heated with urea to 100°, urethane is formed. These 
compounds are also formed by the action of cyanogen chloride 
upon an alcohol : 

/NH, 
CI - C = N + 2HO.C2H5 = CO -h C2H5CI. 

\OC2H, 

The urethanes are solid crystallisable compounds, which are 
decomposed by alkalis, with formation of ammonia, alcohol, and 
a carbonate. 

AUaphanates. The ethers of allophaiiic acid stand to biuret 
(Vol. I. p. 652) in the same relation aa the urethanes (carbamic 
ethers) to urea, thus : 

(Allophanic Amide). Allophanic 



Urea. 


Uretlvane. 


Biuret. 

/NH, 
CO 


Ethylether. 

CO 


\NHj. 


CO 
\O.C4H. 


CO 


CO 
\O.CjH5,. 



1C6 COMPOUNDS OF MONAD ALCOHOL RADICALS. 



These allophanic ethers are formed by the action of the vapour 
of cyauic acid upon the anhydrous alcohols, thus : 

2C0.NH + CA-OH - NH { gg;^'^^^ 

They may also be prepared by heating a chloro-carbonate with 
urea: 

/OCaH. rCO.NHa 

NH-CO-NH2+CO - NH^ + IICl. 

H \C1 ( OO.OCjHj 

Free allophanic acid is not known, but in addition to the 
ethereal salts a few unstable compounds have been prepared, 

such as the following : NH < n(\Qn tj 

Compound Oiuinidines. These bodies are formed by the 
action of cyanamide upon a hydrochloride of a monamine, as 
guanidine itself is obtained by the action of cyanamide upon an 
ammonium salt (Vol. L p. 680) : 

N(CH3)H.HC1 
C^N I 

I ^ + N(CH8)H3Cl = C = ^^1I. 

MI, I 

Guanidines containing two alcohol radicals have, as yet, not 
been prepared, although some containing three such radicals have 
been obtained. These arc formed with separation of carbon 
dioxide, when an isocyanuride is heate<l with an alcoholic solu- 
tion of sodium ethylate, as also if a disubstituted thio-carbamine 
be heated with a monamine and mercuric oxide : 

CSCNH.CsH.), + JLX.C'JI, + HgO - CiN.C.H^KNlLC.Hj), + ll^jS -i- Ufi. 

Tlie cnmpoimd guanidines resemble guanidine itself in acting 
as {)owerfuI bases. 

109 77(45 Tlkiocya nates and Isotliiocyanntcs, The first of these 
classes of bodies is formed in a similar way to the other ethereal 
salts. Thus, for example, ethyl thiocyanato is obtained on heat- 
ing potassium thiocyanato with ethyl iodide or |>otassinm ethyl 
Bulpliatc. They arc most unpleasant-smelling liquids, which 



COMPOUND TIlIO-UREAa 167 

are decomposed by alkalis with formation of alcohols and a 
•thiocyante. 

The isothiocyanates or ihiocarbimidcs are also known as 
mustard-ails, because the oil of mustard belongs to this group, 
and the various members possess a similar strong pungent 
smelL They are formed by a general reaction. Thus ethyl 
mustard-oil, SCNCgH^, is obtained by mixing an alcoholic 
solution of ethylamino with carbon disulphide, when an ethyl- 
thiocarbimic acid is formed, and this, on heating with a salt of 
mercury or silver is converted into the thiocarbimide : 

NH.C,H, N.aH, 

I II 

OS + HgCL = OS + HgS + HCl 4 

I Etliyl 

8(NH3. C^H,) thiocarlimicle. NH3(C2H5)C1. 

Iodine acts in a similar way with formation of iodic acid and 
free sulphur. Dilute sulphuric acid decomposes these mustard- 
oiJs with formation of an amine and carbonyl sulphide : 

N I ^^ + H,0 = N -[ ^^^^ + COS. 

Compound Thio-Ureas. These are formed by the action of 
ammonia or an amine on the mustard-oils. They are crystalline 
bodies forming salts with acids. 

no The NitrO'ParaffiTis. These compounds are isomeric with 
the nitrites of the alcohol radicals, and arc formed together with 
the latter, when an alcoholic iodide is acted upon by silver 
nitrite. They act as weak acids, and contain one atom of 
hydrogen capable of replacement by a metal, whilst the 
nitrites are neutral bodies, and easily converted by alkalis 
into an alcohol and a nitrite. Nascent hydrogen converts the 
nitro-paraffins into compound ammonias, whilst the nitrites 
in the same way yield alcohols. This last reaction indicates 
the constitution of these two classes of compounds : 

Nitro-ethane. 

/O /H 

(1) C4H..N I + 3H» = QH5.N 2H.,0. 

* \0 \H 

Ethyl nitrite. 

(2) C,H..O— NO + 3H. = CJTj.OH + Nil, + H,0. 



tC8 COMPOUNDS OF MONAD ALCOHOL RADICALS. 



Phosphorus Bases or Plwsphines. These compounds are 
pioduceJ by the replacement of hydrogen in phosphuretted 
hydrogen (phosphine) by alcohol radicals. In their chemical 
properties these compounds exhibit great analogy with phos- 
phine itself, and are classed as primary^ secondary, and tertiary 
phosphmes (the name having become generic). The last-named 
combine with the iodides of the alcohol radicals to form phos- 
plumium iodides, which compounds, as well as the bodies derived 
from them, closely resemble the corresponding ammonium 
compounds. 

The alcohol radicals also form corresponding compounds with 
arsenic and antimony, as well as with baron. 

Ill Compounds of the Alcohol Badicals unth Silicon. Silicon, 
like carbon, is a tetrad. The analogy of the compounds of 
these elements has already been pointed out in the first 
volume. Hence, it is not surprising that the compounds 
of silicon with the alcohol radicals exhibit a close similarity 
to the paraffins. For this reason silicon ethyl, Si(C2H5)^, has 
been termed siliconanane, SiCgHgQ, that is, it may be con- 
sidered to be nonane in which one atom of carbon has been 
replaced by silicon.' Silicononane is not attacked by nitric 
acid. Chlorine gives rise to substitution-products, especially ta 
silico-nonyl chloride, SiCgH^j^Cl, which compound can be con- 
verted into the alcohol, ethereal salts, and other derivatives, all 
containing silicon. 

Compounds of the Alcohol Badicals with Metals. Only a few 
of the metals combine directly with the alcohol radicals. Of 
these, the more important are the metals of the magnesium 
group, aluminium, mercury, lead, and tin. The compounds 
thus formed are all licjuids, and most of them volatile. Those 
of the magnesium group and aluminium inflame spontane- 
ously when brought in contact with air, and are decomposed 
by water with the formation of the hydroxides of the metals, 
and the paraffins. The other compounds do not undergo 
alteration in the air, and are not decomposed by water ; they 
are, however, att'icked by acids. When tlie alkali metals act 
upon the zinc compounds, a portion of the zinc is replaced, 
and a Ixxly having a composition such as NaCgH^ + Zn(C2Hj2 
is formed. It has hitherto not proved possible to isolate the 

* The Tiew held by Duinan that eren car1)on may nnderflo substitution, a view 
to powerfully riiliruleii by Lichig, has thus proved to be true, although not 
exactly in the form anticipated by us author. 



ORGANO-METALLIC BODIES. 169 



compound of the alcohol radical with the alkali metal from this 
zinc compound. 

In general the metallic compounds of the alcohol radicals 
correspond to the chlorides of the metals, though this is not 
always the case, as is shown in the following table : 



NaCl 


NaCjHy 


ZnClg 
HgCl, 
PbCl, 


Hg(C,HJ,. 


SnjCl, 
SnCl, 


Sn,(C,U,),. 
Sn(C,H^,. 



THE ALCOHOLS AND THEIR DERIVATIVES. 

112 These compounds may be divided into three distinct 
classes or groups, primary, secondary, and tertiary alcohols and 
their derivatives. 

rriniary Alcohols and Fatty Acids, The primary alcohols, 
when slowly oxidised, first lose two atoms of hydrogen, and 
are converted into aldehydes (alcohol dehydrogenatum ^), and 
these again readily pass into the fatty acids by the addition of 
one atom of oxygen, the acids being derived directly from 
the alcohols by the replacement of two atoms of hydrogen by 
one atom of oxygen : 

The reactions by which the constitution of the acetic acid 
thus formed has been elucidated, have already been referred to, 
namely, by the electrolysis of the acid and by its synthetical 
preparation from the methyl compounds. Thus we saw that, 
when an electric current is passed through a concentrated 
solution of potassium acetate, the salt which is best suited to 
the purpose, it first decomposes, like an inorganic salt, into 

* Liel»ig, Ann. Chcm. Phann, xiv. 133.* 



170 THE ALCOHOLS AND THEIR DERIVATIVES. 



CgHgOj + K. The liberated metal, however, at once acts upon 
the water, and hydrogen is evolved at the negative pole, whilst 
at the same time the group of atoms liberated at the other pole 
decomposes into carbon dioxide and methyl, CHj, two of the 
latter groups uniting to form ethane, C2Hg. All the other fatty 
acids decompose in a similar way according to the equation : 

SCnRnOg = H, + 2CO2 + (C„.aH2„.0r 

If n-i be written m, "^^ obtain for the hydrocarbon the ex- 
pression (CmH2ni + i)s = C!nH2n + 2, which IS the general formula 
for the paraffins. 

The fatty acids can be obtained synthetically from the alcohols 
containing one atom less carbon by replacing the hydroxyl by 
cyanogen and thus obtaining the nitril, which, when boiled 
with caustic potash, yields the potassium salt of a fatty acid 
This reaction is expressed by the following general equation : 

CnH2n + 1 
CnHjn f 1 I 

I H-KOH + HOH = C=0 4- NH,. 

OK 

The following scheme represents the electrolysis of the fatty 
acids: 

CnHiii + 1 CnH-m + 1 

1 I 



CO, 



H H 



CO,. 



It is then clear that the fatty acids are compounds of the 

t 
organic radicals with carhoxyl, HO — C = O, this latter being 

t 
formed from methoxyl, HO — CH,, this latter group being 

characteristic of the primary alcohols. 

Hence a primary alcohol may bo defined as a body derived 

from a paraffin by the replacement of an atom of hydrogen in 

the methyl group by hydroxyl. Or the alcohols may be con- 

nidered as methyl alcohol in which one atom of hydrogen is 

replaced by an alcohol radical. Hence the following bodies 

arc primary aIcoh<»ls: 



PRIMARY ALCOHOLS. 



171 



Ethyl alcohoL 

CH, 



A 



Hj.OH. 



Butyl alcohol. 

CH. 



■^8 



Isobutyl alcohoL 

CH 



CH. 



h 



HgOH. 



CH2.OH. 



Inactive amyl alcohol. 

H«C CH, 
CH 



■■8 



Active amyl alcohol. 

H3C CH2.OH 

CH 



ca 



CH.,.OH. 



ca 



CH3. 



Kolbe ' has proposed a general nomenclature for the alcohols, 
under which not only the primary but also the other groups 
may be classed, as derivatives of methyl alcohol. To this 
latter compound he gives the name of carbinol, and classes the 
primary alcohols as follows : 



Ethyl alcohol 
Butyl alcohol 
Isobutyl alcohol. 
Amyl alcohol (inactive) 
Amyl alcohol (active) 



Methyl carbinol. 
Propyl carbinol. 
Isopropyl carbinol. 
Isobutyl carbinol. 
Pseudobutyl carbinol. 



This nomenclature has not been generally adopted, although the 
suggestion is not without merit. 

The primary alcohols may not only be distinguished by their 
products of oxidation, but they likewise may be detected by 
the following very delicate reaction.* The alcohol is first con- 
verted into the iodide, and a few drops of this are brought into 
a distillation flask, having a capacity of a few cubic centimeters, 
in which a mixture of silver nitrite and white sand has pre- 
viously been placed. As soon as the violence of the reaction 
has subsided, the liquid is distilled off, and the nitro-paraflBn 
which has been formed is dissolved by shaking with caustic 
potash, and then dilute sulphuric acid added drop by drop, 
when a dark-red colouration takes place. This colour dis- 
appears as soon as the liquid becomes acid, but again makes its 

1 Zei/sch. Chcm. 1866, 118. 

• V. Meyer, Lxebiga AnncUcn^ clxxx. 139. 



172 THE ALCOHOLS AND THEIR DERIVATIVES. 



appearance when the liquid is rendered alkaline by caustic 
potash. So far this reaction has only been applied, in the series 
of piimary alcohols, as high as octyl-alcohol, and thus far with 
success.^ This reaction depends on the formation of a nitrolic 
acid in the following way : 



CH3 CH3 



A 



H2 + ON.OH = C = N.OH + H.O. 

I 
NOo NO. 



2 



A nitrolic acid is also formed when a nitro-paraffin is con- 
verted into the dibromo-compound, and this is acted upon by 
hydroxylamine : 



Ciig CHg 



A 



Br^+H^N.OH = C = N.0H + 2HBr. 



NO2 NOj 

The nitrolic acids are colourless, and crystallise well, forming 
with alkalis dark-red salts, which explains the production of 
the above reaction. They are extremely unstable compounds, 
decomposing easily with formation of a fatty acid. V^hen 
heated with sulphuric acid, this simple decomposition takes 
place, pure nitrogen monoxide being evolved : 

CH3 CH3 



i 



J = N.OH = C = + N,0. 



r 



NOj OH 

113 Aldehydes. It has already been stated that these bodies 
occur as intermediate products in the oxidation of the alcohols 
to fatty acids. They are oxides of dyad radicals, and in their 
formation the first step is, in the cases of acetaldehydes, the 
production of ethidenc alcohol : 

CH, CH3 



CH..OH C] 



!H(OH),. 
Thisi however, like all other compounds containing two hydroxyl 

1 Gutknccht, Ber. Dcuttch. Chcm. Of*, xii. 622. 



ALDEHYDES. 173 



groups, combined with one carbon atom, splits up with separation 
of water, and we have the anhydride or oxide left ; in the above 
case ethidene oxide or acetaldehyde being formed : 

Ethidene alcohol. Acetaldehyde. 

^^3 CH, 



^^\0H HC=0 



That the above formula expresses the constitution of this 
compound is seen from the fact that by the action of phos- 
phorus pentachloride it is converted into ethidene chloride or 
dichlorethane : 

CH3 CJH3 

I + PCI5 = I + POCI3. 

CHO CHCl, 

We may, however, acording to the theory of radicals and of 
types, consider aldehyde, CgHgO.H, as the hydride of an acid 
radical having the general formula CnHgn-iO. All the alde- 
hydes are characterised by possessing a peculiar suffocating 
smell, whilst another peculiar characteristic of these bodies is 
that they unite with the hydrogen sulphites of the alkali-metals 
to form crystalline compounds, which are generally diflScultly 
soluble, and are decomposed by acids with separation of the 
aldehyde, and hence this property is frequently made use of 
for the purification of these bodies. 

On oxidation the aldehydes yield the fatty acids, and if 
fireshly precipitated oxide of silver be employed as the oxidising 
agent, the following reaction takes place : 

2 CH3.COH + SAgP = 2 CH3.CO.OAg + HgO + 2 Ag.^ 

When heated with ammoniacal silver solution a similar reaction 
occurs, and if the aldehydes are soluble in water, metallic silver 
is deposited on the sides of the containing vessel in the form^of 
a bright mirror. 

114 Haloid Campoiinds of the Acid Radicals. The chlorides 
and bromides of the acid radicals are easily formed by the 
action of the cliloride or bromide of phosphorus on the acid : 

3 CH3.CO.OH + PCI3 = 3 CH3.COCI -f P(0H)3. 



174 THE ALCOHOLS AND THEIR DERIVATIVES. 



These bodies are, as a rule, liquids which fume strongly in 
contact with the air, and possess a powerful acid smell, depending 
on the fact that they are rapidly decomposed by water into the 
corresponding fatty acid and the hydracids : 

CH3.COCI + Ufi = CH3.CO.OH + HCl. 

The iodides, which as yet have been but slightly investigated, 
are not formed by the action of iodide of phosphorus on the 
acids, inasmuch as a further decomposition takes place witli 
separation of iodine. They may, however, be prepared from 
the anhydrides, and are decomposed by water in a similar way 
to the ddorides and bromides. The haloid compounds of the 
acid radicals can thus be distinguished from those of the alcohol 
radicals, and this explains the fact that the former cannot be 
obtained by the action of the hydracids on the acids as the 
alcoholic chlorides are prepared by the action of the hydracids 
on the alcohols. They may, however, be obtained in this w^ay 
in presence of phosphorus pentoxide : ^ 

CH3.CO.OH + HCl + P2O5 = CH3.COCI + 2 HPOj. 

115 Ethereal Salts or Compound Ethers, The fatty acids are 
monobasic, and the one atom of hydrogen can be replaced not 
only by metals, but also by acid radicals, and thus the bodies 
formerly known as compound ethers are obtained. These are 
now generally termed the ethereal salts, and they may be 
prepared in a variety of ways: 

(1.) An alcohol is brought in contact with an acid chloride : 

Ethyl Acetate. 
C2H5 \^ , CpHj^O ) C2H5 ) ^ xrpi 

(2.) An acid is allowed to act upon an alcohol : 

C2H5 } r) , C2H3O ) Q _ C-Hr, ) Q TT Q 

In this case the formation of the ethereal salt takes place 
slowly in the cold, but more quickly when heated. When a 
certain quantity of water is formed, the reaction becomes feeble, 
and at lost steps. On the other hand, the ethereal salts are 
decomposed by water into the alcohol and the acid. 

^ Friedel, Contpi, Rend, Ixviii. 1557. 



ETHEREAL SALTS. 175 



(3.) When hydrochloric acid is passed into a mixture of the 
acid with alcohol, the formation of the ethereal salt takes place 
more perfectly and more quickly. Tins depends partly on the 
fact that hydrochloric acid acts as a hygroscopic agent, but 
partly, no doubt, because hydrochloric acid increases the 
yield by the fonnation of the acid chloride, which then acta 
according to equation No. 1, as these chlorides will attack the 
alcohol more readily than water. It is, moreover, possible 
that the alcohol is first converted into the chloride, which then 
acts again upon the acid : 

C2H5 ) CoH.,0 1 r\ C/oHf 



Cl 



} + '''%}o = ^;g:o}o + Ha 



Indeed, perhaps the whole of these reactions come into play.* 

(4.) Concentrated sulphuric acid acts in a similar way to 
hydrochloric acid. Hence the ethereal salts are frequently 
prepared by mixing the acid or an alkaline salt of the same 
with the alcohol and concentrated sulphuric acid and heating, 
or, again, a mixture of equal molecules of the acid and alcohol 
is allowed to run into a warm mixture of the alcohol with an 
excess of sulphuric acid, when the ethereal salt is formed to- 
gether with water, and both distil over. The following equation 
represents the reactions which take place : * 

(b) C2H5 1 gQ^ _^ C^H^O I Q ^ ^C^H, J Q ^ g^gQ^ 

(5.) Ethereal salts are lastly formed by heating the salt of a 
fatty acid with (a), a haloid ethereal salt, or (6), with a hydrogen 
sulphate of an alcohol radical : 

* Demole, Ber. DeuUeh. Chem, Qe$. 1877, 1790 ; Henry, tft. 2041. 

* Markownikoff, Ber, DeuUch, Chtm, Ofs. ▼!. 1176. 



176 THE ALCOHOLS AND THEIR DERIVATIVES. 



Ii6 Anhydrides or Oxides of ilie Add Radicak^ These com- 
pounds stand in the same relation to the acids as the ethers 
of the alcohol radicals do to the. alcohols. 

Tliey are formed by the action of the haloid salts of the acid 
radicals on the salts of the acids : 



2^3^ ) . C2H3O ) o - ^2^3^ I O 4- NaCl 
21/ ^ Na/ ^ " CgHjOj^ + ^^^^• 



C.H 

CI 



The anhydrides are insoluble in water, but when placed in 
contact with it, they decompose slowly in the cold, and more 
quickly when heated, yielding two molecules of the acid. This 
decomposition takes place more rapidly in presence of alkalis or 
in presence of alcohol, when an ethereal salt is formed : 

Hydrochloric acid decomposes the anhydrides in the following 
way: 

cSS } O + HCl = W^Oj } 4- ""'^^ ] O, 



and the phosphorus compounds of the chlorine group act 
similarly : 

117 ThtO'Cornjwinids of the Ami Radicals, Thio-Acids are 
formed by the action of phosphorus pentasulphide on the fatty 
acids : 

The phosphorus pentoxide which is thus formed acts on a 
portion of the thio-acid with formation of other products of 
uncertain composition. 

The thio-acids which have hitherto been investiimtcd are 
liquids possessing an unpleasant smell, and forming salts of 
which some, such as the lead and silver BsAts, are easily dccom- 
po.sed with formation of the sulphide of the metal. 

T/ic TliiO'Anhydrides or Sulphides of the Acid Radicals are 
obtained by the action of sulphi<le of phosphorus on the oxides. 



AMIDES. 177 



These arc also unpleasant smelling liquids, which are decomposed 
by water in the following way : 

The thio-acids also give rise to compound thio-ethereal salts 
obtained by heating the ordinary acid ether with sulphide of 
phosphorus, as also by decomposing the salts of the thio-acids 
with haloid ethers, and lastly by the action of the acid chlorides 
upon the mercaptides : 



CgH 



f^}s + ^*'fe?}H = C;h;o}s + NaCl. 



Ii8 Amides, The acid radicals are capable of replacing 
hydrogen in ammonia, thus giving rise to compound ammonias 
which, in order to distinguish them from the amines, are termed 
amides. In order to prepare these bodies the following 
reactions are employed : 

(1.) The acid chloride or the anhydride is treated with dry 
ammonia : 

(a) C2H3OCI + 2NH, = C2H3O.NH2 4- NH.Cl. 

Qj) {G^YLf>\0 + 2NH3 = C2H3O.NH2 + O0H3O2NH,. 

(2. ) An ethereal salt is treated with alcoliolic ammonia : 

*^7???l0 + NH, = CHaO.NH, + aH^.OH. 

(3.) The ammonium salt of the acid is heated : 
C.HgO.ONH, = CgHoO.NHg 4- H,0. 

When the amides are heated with phosphorus pentoxide 
they yield nitrils with liberation of water. Phosphorus penta- 
sulphide also produces the same reaction : 

5aH,0.>'H. + P.S, = r)C),H„.N + r)HoS4PoO.. 

If the salt of a monamine be employed in reaction No. 3, 

instead of an ammonium compound, an amide is obtained in 

which one atom of hydrogen is replaced by an alcohol 

vor^ III. M 




178 SUBSTITUTION PRODUCTS OF THE FATTY ACIDS. 



Such compounds are also formed by acting with a carbimide 
on a fatty acid : 



N 



jCA ^ C,H30|o = n|^H, 4- CO,. 



The amides containing two or three acid radicals have as yet 
been but slightly investigated. The first is formed when a 
nitril is heated with a fatty acid : 



an^o.oH H- 



'2*^3 



( C2H30 

C.HjN = N^aH30 



And if instead of the acid, the anhydride be employed, a triamide 
is produced : 

(C,H80)20 + C^HjN - NCCaHaO),. 
The anhydride and a carbimide yield the following reaction : 



^^{cb^* ^ c:h;S}o = n|c|:8 



+ COo. 



Wlien ureas, thio-ureas, and similar compounds are treated 
with an acid chloride, one atom of hydrogen is also replaced by 
an acid radical. 

119 Substitution Products of the Fatty Acids, Chlorine and 
bromine attack the fatty acids, especially when heated, or in 
presence of iodine, the hydrogen in the alcohol radical being 
replaced. Thus acetic acid yields : 

Monocliloraoctic ncid. Dicbloracctic acul. Trichloracetic acid. 

CH.,C:.CO,H CHCU.CO,H CCI3.CO2H. 

In the higher members, this substitution invariably takes place 
in connection with the carbon atom which is combined with 
the carboxyl. Thus propionic and butyric acids yield as first 
substitution products : 

a Chlorpropionic acid. a Brombatyric acid. 

CHj CH, 



CHCl CH, 



CO.OH CHBr 

I 

oo.uu 



SYNTHESIS OF THE PRIMARY ALCOHOLS. 



179 



Iodine does not. form direct substitution products. In order to 
obtain these bodies the ether of the chlorinated or brominaited 
acid must be heated with potassium iodide, and the acid set 
free from the product. When such an iodo-acid is heated with 
hydriodic acid, a fatty acid is again formed, from which it is seen 
why free iodine cannot act upon these bodies : 

CHgl.CO.OH + HI = CH,,CO.OH + 1^. 



SYNTHESIS OF THE PRIMARY ALCOHOLS AND 

THE PATTY ACIDS. 

120 Whilst almost all the members of the homologous series 
of fatty acids have been long known, our knowledge respecting 
the corresponding alcohols has only recently been rendered 
complete. 

As the alcohols may be so easily converted by oxidation into 
the fatty acids, a method of realising the inverse reaction, and 
of converting the acids into the alcohols, did not appear diflScult 
of attainment. This problem attracted the attention of many 
chemists, but the first attempts proved abortive, and it was not 
until after Mendius * had discovered that the nitrils can unite 
with hydrogen to form the amines, that this question was solved. 
This method promised, moreover, likely to yield results of more 
general interest, inasmuch as it seemed that by this means the 
whole series of acids and alcohols could be synthetically built 
up. For Frankland and Kolbe,^ as well as Dumas, Malaguti, 
and Leblanc,* had shown in 1847 that the nitrils or cyanides of 
the alcohol radicals can be converted into the fatty acids by 
boiling with potash, and Hofmann * had converted the amines 
into the corresponding alcohols by the action of nitrous acid. 

Now the lowest member of the nitril series is hydrocyanic 
acid or formionitril, and this combines directly with hydrogen 
to form methylamine. But methyl alcohol can be obtained 
from this latter compound, and this again can be converted into 
methyl cyanide or acetonitril, which, in its turn, can be made 
to yield acetic acid and ethyl alcohol. Here, however, the 
simplicity of the reaction ends, for when the same operation is 
conducted in the next group, a mixture of isomeric alcohols is 



' Ann. Chen. PJiarm, cxxi, 129. 
' Compt. Rend, xxv. 442, 656. 



' Chem. Soc, Journ. i. 60. 
* Chem. Hoc. Journ. iii. 231. 



180 LIE3EN AND ROSSI'S SYNTHETIC METHOD. 



obtained, and these cannot readily be separated. The cause of 
this will be explained later on. 

Other general methods may, however, be employed for the 
synthetical formation of the alcohols and acids corresponding to 
the normal paraffins. 

In I80I Williamson * showed that when a mixture of a for- 
mate and a salt of a fatty acid is heated, the aldehyde of the 
latter is produced : 

Five years later this was confirmed by the experiments of 
"Limpricht^ and Piria,^ and when Wurtz* in 1862 had dis- 
covered that the aldehydes combine directly with nascent 
hydrogen to form the alcohols, no further obstacles were seen 
to present themselves to a systematic construction of the homo- 
logous series of the acids and alcohols. Many unperceived 
difficulties were, however, met with in the practical carrying out 
of the process, and it was not until the year 1860 that Lieben 
and Rossi ^ sufficiently perfected the methods, by means of 
v/hich, beginning with ordinary alcohol, the whole series of 
normal primary alcohols and the corresponding acids could be 
synthetically obtaine<l. 

Lichen and Iiossi*8 Method. The first step of this process is 
the preparation of propionic acid from ethyl alcohol by means 
of acetonitril, and then heating its calcium salt with calcium 
formate. In this way propioaldehyde is obtained, and this com- 
bines directly with hydrogen to form propyl alcohol. From 
this latter propyl cyanide (butyronitril) can be prepared, and 
tliis again, in a similar way, yields butyr-aldehyde and butyl 
alcohol, &c. 

Fatty acids are also formed by the action of carbon dioxide 
on the compounds of the alcohol radicals with the alkali 
metals (Wanklyn) : " 

(^,H,Na + CO., = (^H,.CO.Na. 

Frankitind nrul Dnppa's Method, Another metho<l discoveretl 
by Frankland and Duppa and imiT(»vc<l by other chemists, not 

» i'hrui, Soc. Journ. iv. 13S. = Ann. Chem. Diarm, li. 201. 

' Ami. Ckim, xlviii. 113 : Ann. Chem. Pharm^ c. 104. 
* Compt. RrniL liv. IH4. 

' Ann. Chnrt. Phann. rlviii. 137 ; rlix. .'JS, 70 : tlxv. 109; olxvii. 203 ; I it-lien 
an I .Taii»'«*ok, ih. ilxxwi-. \'1*\. •• Wanklyn, f"hr,ii. Si>c. Joitrn. xi. 1(»3. 



FRANKLAND AND DUPPA'S METHOD OP SYNTHESIS. 181 



only enables us to prepare the fatty acids synthetically, but also 
the other series, and a variety of other compounds.^ This 
depends upon the fact that the hydrogen of the methyl in 
acetic acid can be replaced by a carbon-containing radical. For 
this purpose, sodium is dissolved in acetic ether, when sodium 
aceto-acetic ether and sodium ethylate are formed : 

(;h, CH 



CO.OCH, CO 

f iNa^ = I -f NaOCgH, + H... 

CH, CHNa 



I 



O.OC2H, CO.OCoH,, 

In this reaction, however, little or scarcely any hydrogen is 
evolved in the free state, as this, in the nascent condition, 
reduces a portion of the acetyl in the acetic ether to ethyl, 
forming sodium ethylate. If acetic acid be added to the solid 
product, aceto-acetic ether is formed. This possesses slightly 
acid properties due to the presence of two carbonyl groups, and 
when acted upon by sodium, yields the original compound in 
the pure state. The sodium in this body may readily be sub- 
stituted by an alcohol radical on treatment with an alcoholic 
iodide, and in this compound the second atom of hydrogen can 
be substituted by sodium, and this in its turn again replaced by 
an alcohol radical.^ 

All these compounds, like acetic ether itself, are decomposed 
by concentrated caustic potash, in the following way : 

CH3 CH, 



CO CO. OK 

I + 2H0K = + HO.C»H,. 

CXY CHXY 



2 o' 



CO.OGM, CO.OK. 

In these formulsB X and Y represent either hydrogen or an 
alcohol radical It is clear that by this reaction not only homo- 
logous acids but many isomeric acids may be built up, as, for 
example, in the following instances : 

* Concerning the history of this subject, see Wislicenus* ** Synthesis of Aceto- 
acetic Kthers,** Li^, Ann. clxxxvi. Idl. 

* Ob tliis suhject see Conrad and I impach, Lich, Ann cxcii. 153. 



182 SECONDARY ALCOHOLS AND KETONE& 



Pt'utylic acid. 


Valerianic acid. 


Methyl-ethyl acetic acid. 


CH 






1 


CHo Cxia 


CH, 


CHj 
CH, 


V 

1 


CH, 


M 


CH, 


CH CH,. 


CH, 






mt 


CO.OH 


CO.OH 


CO.OH 







Pentylic acid is obtained by replacing one atom of hydrogen 
in acetic acid by the primary radical propyl, whereas secondary 
propyl yields valerianic acid. In order to obtain the third acid, 
sodium aceto-acetic ether is, in the first place, treated with 
iodide of ethyl, the ethyl compound is then acted upon by 
sodium, and the body thus obtained converted, by means of 
methyl iodide, into methyl-ethyl aceto-acetic ether, and this 
finally decomposed by caustic potash. 



SECONDARY ALCOHOLS AND KETONES. 

lai The secondary alcohols, the existence of which was pre- 
dicted by Kolbe * in 18GG, may be regarded as methyl alcohol, in 
which two atoms of hydrogen are replaced by alcohol radicals. 
The first of these secondary alcohols, CjHgO, was prepared by 
FriedeP by the action of hydrogen (2) on acetone, CjH^O, 
obtained on the dry distillation (1) of calcium acetate : 

(I) CH3.C().0 ) ^, _ CHgX.^^ rvPOs 

<2) g{5«}C0 + H, = g{j3lcH.0H. 

Other fatty acids yield ketones when treated in a similar way, 
and these are also formed, as Freund ^ has shown, when an 
acid chloride acts upon the zinc compound of an alcohol radical. 
Thus acetyl chloride and zinc ethyl give mcthyl-ethyl-kctone : 

Zn(C.,HJ, + 2CICO.CH3 = 2CjH,.CO.CH3 + ZnCI,. 

» Zeitsch. Cktm. I.<i6«, 118. « rnmpt. Rend, Iv. 50. 

^ Ann, f.'hem. Phnrin. rxviii. 1. 



SECONDARY ALCOHOLS. 183 



The same compound^ together with dimethyl ketone and diethyl 
ketone, is obtained when a mixture of calcium acetate and 
calcium propionate is heated. The formation of the ketone 
from the &tty add is, therefore, exactly analogous to that 
of the aldehyde from a mixture of the salt of a fatty acid and 
a formate. Whilst just as the aldehydes were formerly con- 
sidered to be hydrides of the acid radicals, so the ketones were 
looked upon as compounds of the latter with alcohol radicals. 

Another general method for the preparation of the ketones 
is the decomposition of the acet-acetic ethers by baryta water : 

I CH3 

CO I 

I + Ba(0H)2 = CO + HOCoH, -t BaCO,. 

c: 



CO. 



IHXY 



OCjH, 



The ketones combine directly with nascent hydrogen with 
formation of secondary alcohols. 

The secondary alcohols can also be obtained by various other 
reactions. Thus all the olefines which contain the groups 
— CH = CHg and — CH = CH — dissolve in sulphuric acid 
with formation of an acid ethereal salt, which when heated with 
water yields the alcohol : 

^^\>CH.0.S02.0H + H,0 = ^g3\cH.0H 4- HO.SO2.OH. 

These olefines also combine with the hydracids to form the 
haloid ethereal salts : 



CH3 

CHj 

CH 

1 

CHj 






CH„ 

•• 

CHj 


+ 


r 1 

HI 


CHI 

GHn. 

•1 


(JH, 






CH, 


CH 

II 
CH 


+ 


'h} " 


CHT 
CH., 



CH« CH, 



184 SECONDARY ALCOHOLS AND KETONES. 



By the action of chlorine upon the paraffins, secondary as 
well as primary chlorides are formed, whilst with bromine only 
secondary bromides are produced.^ 

Secondary iodides are formed when the alcohols of polyvalent 
radicals are heated with concentrated hydriodic acid and 
amorphous phosphorus. Thus, glycerin, 03115(011)3, yields 
secondary propyl iodide ; 

OH2.OH OH3 

OH.OH + 5HI = OHI + 3H.0 + 2L. 



OHo-OH OH3 

Phosphorus is added for the purpose of preventing the liberation 
of iodine: 

2 OjHgOg + 2 HoO + P, + Ig = 2 O3H7I + 2H3PO,. 

From these iodides, the alcohols may be obtained by the action 
of freshly precipitated oxide of silver. 

The alcohols may likewise be obtained by heating the iodides 
with concentrated acetic acid and anhydrous acetate of lead in 
closed tubes, the ethereal acetates thus formed being decomposed 
by caustic potash. This latter reaction is also employed in 
order to convert the chlorides and bromides into alcohols. 

By the action of silver nitrite on the secondary iodides, nitro- 
paraffins are obtained. These dissolve in caustic potash, and 
when sulphuric acid is added to this solution a deep-blue 
colour is produced. When shaken with chloroform this coloured 
compound dissolves, and on evaporation of the dark-blue solu- 
tion, colourless crystals of a pseudo-nitrol arc obtained : 

Propyl-pseudonitrol 
]i)0-nitro ])ropanc. or Nitro-nitro80-proi>anc. 

CH3 C;H3 

I J /NO.. 

CH— (NO.,) + NO.OH = c; ' + H.,0. 

I, ' |\^'^ 

CH., CH.. 

Small traces of a secondary compound can be recognised by 
this reaction, but it is only applicable to the lower terms of 
the series.- The pseudo-nitrols are colourless in the solid state, 

» Srhorlemmer, /Vii7. Tnins. rlxii. (1^72) 111 : Ih. dxix. (1878) iO. 
' Meyer and Locher, Lieb. Ann, clxxx 139. 



CONSTITUTION OF SECONDARY ALCOHOLS. 186 



but when fused or in solution they possess a deep-blue colour. 
On oxidation they first form ketones : 

Propyl-pfiendonitrol. Dimethyl-ketone. 

CH3 CH3 

O = N— C— NO., + H2O -r 30 = CO 

1^ ' I 42HNO3. 

The secondary alcohols also easily form ketones on oxidation, 
and these on further oxidation decompose in such a way that 
the carbonyl remains in combination with one alcohol radical, 
whilst the other yields oxidation products like its corresponding 
alcohoL* Hence dimethyl ketone yields acetic acid and formic 
acid, the latter however, readily undergoes decomposition into 

p2 5^ and 

( OH 
methyl propyl ketone, CO •} n ijf > hot-h yield acetic and propionic 

acids, whilst from methyl iso-propyl ketone, CO -J npr/pij \ 

first acetic acid and then dimethyl ketone is obtained, which 
latter is further oxidized as before described. 

From this it would appear that the simplest alcohol radical 
always remains ip combination with the carbonyl. This is, how- 
ever, not always the case. Thus, for example, from tri methyl - 

carbylmethyl ketone, CO -! p/rvrj \ ^vc obtain trimethylacetic 

^^ 1 rOOH^ *^^ formic acid. 

Hence, in many cases, the constitution of the secondary 
alcohols can readily be recognised by their products of oxida- 
tion. Thus, for example, a secondary alcohol is obtained from 
mannite, CoHg(OH)g, which, when completely oxidized, yields 
acetic and butyric acids, and, therefore, must bo considered ikh 

methyl butyl carbinol, ^^^ \ CO.OII. 

The ketones act in many respects, like aldehydes, as oxides 
of dyad radicals. Phosphorus pentachloride converts them into 
the dichlorides : 



3} CO 4 rci, = f^Jl'CCi, + P0CI3. 



CH 

CH3f^^^' -r -•. = (jHJ 

' Popofl", Ann. Chcm. Phann. clxi. 28ri. 



186 TERTIARY ALCOHOLS. 



Many ketones also combine with the hydrogen sulphites of 
the alkali metals to form difficultly soluble crystalline com- 
pounds which are decomposed again by an excess of acid or 
alkali. Hence this reaction is often employed for the purification 
of the ketones. 



TERTIARY ALCOHOLS. 

122 A general method for the preparation of these alcohols, 
the existence of which was also predicted by Kolbe, has been 
discovered by Butlerow.^ This consists in placing an excess of 
the zinc compound of an alcohol radical in contact with the 
acid chloride for severpJ days, when a crystalline mass is 
formed : 



CH, 



CH, 



i 



4- 2(CH3)JZn = CH3— C— O— Zn— CH3 

joci *■ I ^ 7 fCl 

CH3 ^ tCH3. 



We may assume that as in the case already mentioned, 
(p. 182) a ketone is hero first formed, and that this unites with 
one molecule of the zinc compound, in a similar way as it does 
with hydrogen to form a secondary alcohol. If the above com- 
pound be next treated with water, tertiary butyl alcohol, or 
trimethyl carbinol, is obtained, and this is the first member of 
this scries : 

(CH3)3C.O.ZnCH3 + 2H,0 = (CH3)3C.OH + Zn(0H)2 -h CH,. 

The tertiary alcohols are also formed by the direct union witli 
water of the olefines containing the groups 

— [;y: = OH, and Zc/f' = ^^H— 

CII3 CH3 CH3 CH, 

\/ \/ ' 

Thus: -h H>C) = OOH 

II I 

» Zfitjtrh, r^hnn. 1864, 3«r». 702. 



OXIDATION OF TERTIARY ALCOHOLS. 187 



This combinatiou takes place with especial ease in presence of 
sulphuric acid or nitric acid.' 

The same defines readily unite with the hydracids to form 
tertiary haloid ethereal salts. 

The tertiary alcohols are at once broken up on oxidation in 
such a manner that the carbon atom which holds the group 
together remains in connection with one alcohol radical forming 
a fetty acid, whilst the two other alcohol radicals yield the 
same oxidation products as their corresponding alcohols do. In 
this way ketones frequently occur as intermediate products. 
Thus trimethyl carbinol first yields formic acid and dimethyl 
ketone, and the latter readily splits up into water, carbon dioxide 
and acetic acid. This last product is also obtained from methyl 
diethyl carbinol, whilst propionic acid is also formed from the 
isomeric dimethyl propyl carbinol. It is a singular tsyct that in 
these oxidations a small quantity of a fatty acid is obtained 
which contains as much carbon in the molecule as the tertiary 
alcohol. This is, however, not difficult to explain. The tertiary 
alcohol easily decomposes into water and an olefine, and these 
latter, as we have seen, readily combine with water to form a 
tertiary alcohol. It is also possible that, under certain circum- 
stances, a primary alcohol may be produced, and the formation 
of isobutyric acid from trimethyl carbinol may be explained by 
the following equations : 

(CH3)2C(OH)CH8 = (CH3),C : CH^ + HgO. 

(CH3)2C : CH2 4- H.3O = (CH3)2CH.CH20H. 

Isobutyl alcohol is thus obtained, which, on oxidation, yields 
isobutjnric acid.2 

123 Tertiary nitro-paraffins are formed with difficulty. They 
do not possess any acid properties, and hence they do not 
dissolve in alkalis and do not give any reaction with nitrous 
acid. 

The reason that these tertiary compounds do not act as acids 
is not far to seek. In order that a replacement by a metal can 
occur, the carbon compound must contain acid-forming or 
negative elements or radicals united to a carbon atom, which 
latter must also be united to an atom of hydrogen or hydroxy!. 

* Butlerow, Lieb. Ann. clxxx. 245. 

* Butlerow, Zcitsch. Chan, 1871, 484; Lich. Ann. clxxxix, 173. 



•i 



188 



TERTIARY ALCOHOLS. 



Hence acetic acid is an acid. Its anhydride (acetyl oxide) is, 
however, not an acid. The same reasoning applies to the 
uitro-paraiBns. 



Nitro-e thane. 

CH3 

CH, 



Secondary 
Nitropropane. 

CH3 



NO.. 



CH.NO, 
CHo. 



Tertiary 
Nitrobutane. 

CH3 CH3 

C.NO. 



CH3. 



Bromnitro-ethane. Dibromnitroethane. 



CH3 

CHBr 

NOo. 



CH 



8 



CBr. 



Secondary 
Bromnitropropane. 

CH3 

BrC— NOo 



NOo. 



CH3. 



The two first of these bodies only act as weak acids, whilst 
bromnitro-ethane, obtained by the replacement of hydrogen by 
negative bromine, is a strong acid. All the other compounds 
are, however, perfectly neutral.* 

It has already been stated that a mixture of isomeric alcohols 
is obtained by the action of nitrous acid upon primary amines 
which contain more than two atoms of carbon. The fact that 
in this case the alcohols produced are not homogeneous had 
been overlooked, and it was thought that propylamine, for 
example, was converted by the above reaction into secondary 
propyl alcohol, and isobutylamine, in like manner, into tertiary 
butyl alcohol.- As soon, however, as the fact of the production 
of a mixture of alcohols became apparent, a somewhat far-fetched 
hypothesis was made use of, until at last a very simple explana- 
tion was found,^ namely, that the reaction goes on quite nonnally 
up to a certain point, and that a primary alcohol is pro- 
duced from propylamine, but another ]K)rtion of the propyl- 
amine is converted into propyleno, which is jMirtly evolved as 
a gas and partly combines with water to form a seconilary 
alcohol : 



* V.MeycT, Lub. Ann, clxxx. iii. 
- Liuneinanii, Ann, Chem. Phann, clxi. ATt ; clxii. 3. 

=* Mover and Forstcr. Drutsch, f'hrin. Ors. Bcr. ix. .^:j.1 ; Mrvor, Bubicri, and 
F<irstir, X. l.'^M. 



NITRO-PARAFFINS. 189 



CH3 CH3 

I I 

CHo + HO.NO = CH + N^ + 2H<,0. 



CHj.NHo • CH., 

CHj CHj 

I I 

CH + HjO = CH.OH 

II I 

In a similar way isobutylamiDO yields isobutyl-alcohol, iso- 
butylene, and trimethylcarbinoL 



190 THE METHYL GROUP. 



THE METHYL GROUP. 

METHANE OR METHYL HYDRIDE, CH^. 

Z24 The existence of this substance was observed by the an- 
cients, as Pliny noticed the occurrence, in several localities, of jets 
of combustible gases. In later times we find that Basil Valentine, 
in describing the outbreaks of fire which occur in mines, men- 
tions a suffocating damp which is noticed before such an outbreak. 
He does not, however, appear to consider that the gases issuing 
in such emanations are combustible, but rather that the fire 
comes out of the rock and drives out the poisonous air. Libavius, 
likewise, gives an account of an explosive fire-damp ; and during 
the seventeenth and eighteenth centuries a large number of 
descriptions arc found of explosions which occur in mines, and 
especially in coal-pits. At the same time no distinct statement 
is made of the nature of this inflammable fire-damp, which, like 
other combustible gases, was not at that time distinguished from 
hydrogen. 

Fire-damp as well as the gas of marshes was then con- 
sidered to be poisonous, nor was it until the year 177G that 
Volta^ pointed out the inflammable nature of the latter gas. 
He showed that marsh gas differs from hydrogen, in requiring 
twice its volume of oxygen for combustion, as well as in giving 
rise to carbondioxide, whilst ordinary inflammable air needs only 
half its volume of oxygen for combustion and yields no carbon- 
dioxide. In 1785 BerthoUct investigated the properties of marsh 
gas more accurately, and found that it contains both carbon and 
hydrogen, and that it usually occurs mixed with nitrogen. All 
the naturally occurring infliimmable gases were, however, con- 
sidered to be identical with the gases obtained artificially by the 
dry distillation of organic matter, a.s well as with the substance 

* JSuir aria injlamniabilc )ui/mi dcUt jmludi. MiUno. 1777. 



METHANE OR METHYL HYDRIDE. 191 

known as defiant gas, until William Henry,* in 1805, proved 
that the gases obtained by the destructive distillation of coal, 
oil, and wax, contain two distinct gaseous hydrocarbons, viz., 
defiant gas and carburetted hydrogen (marsh gas) mixed with 
carbonic oxide gas. Shortly afterwards Dalton,* Davy, and 
Berzelius confirmed the existence of two distinct gaseous com- 
pounds of carbon and hydrogen, which, from their difference in 
specific gravity, were termed light, and heavy, carburetted hy- 
drogen, the former being marsh gas and the latter olefiant gas. 
The first of these was afterwards looked upon as methyl hydride, 
and the name methane given to it by Hofmann. 

125 Properties, Methane is a colourless inodorous gas which, 
according to Cailletet, can be liquefied under a pressure of 180 
atmospheres at a temperature of — ll^ Its specific gravity 
was determined by Thomas Thomson ^ to be 0*555. 

Marsh gas is not poisonous, and colliers who frequently 
breathe air containing 9 per cent, of this gas do not appear to 
suffer. When the percentage increases above this point, pressure 
on the forehead and eyes is noticed, which, however, disappears 
again on gaining the open air. 

Methane is readily inflammable, burning with a slightly lumin- 
ous flame, which in the upper part has a yellow, and in the 
lower a blue, colour. When mixed with double its volume of 
oxygen, and fired by an electric spark or by a flame, it explodes 
more violently than the same volume of electrolytic gas, and a 
mixture of marsh gas with from seven to eight volumes of air 
also explodes with great violence. Mixtures of air and marsh 
gas varying from this proportion bum with a weaker explosion, 
and if one constituent be present in large excess the electric 
spark does not explode the mixture (Davy). 

Methane is but slightly soluble in water; its coefficient of 
absorption, according to Bunsen, for temperatures between 0** 
and 26** is obtained from the following interpolation formula : 

c. = 0-05449 - 0011807t + 0000010278t*. 

It is more soluble in alcohol, the following formula giving its 
solubility in that liquid between 2"^ and 24** : 

c = 0-52258G - 00028655t + 00000142t2. 

* Nicholswi's Jiunuil, xi. p. 65. * Vol. I. p. 612. 

'^ NicholsorCs Journal, 1807. 



192 TUE METHYL GROUP. 



It has already been mentioned that methane occurs in nature.* 
Thus it forces its way out together with petroleum at various 
points on the earth's surface. Tlie sacred fire at Baku consists 
of burning marsh gas containing admixtures of nitrogen, carbon 
dioxide, as well as of the vapour of petroleum (Hess). The gas 
issuing from the mud volcanoes at Bulganak, in the Crimea, on 
the other hand, consists, according to the analyses of Bunsen, of 
perfectly pure methane. It has already been stated in the first 
volume (p. G08) that the gases which escape in large quantities 
from the oil wells of Pennsylvania contain marsh gas and its 
homologues, together with hydrogen. 

Marsh gas not only occurs in these sources and in very large 
quantities in the coal measures, but it is also found in many 
sulphur springs in the neighbourhood of active volcanoes, and it 
is likewise evolved in the boric acid fumeroles in Tuscany. 
Moreover, methane is a never-failing constituent in the pro- 
ducts of the dry distillation of organic matter, and hence it is 
found in large quantities in coal gas.^ 

126 Preparation, Methane is obtained when either acetic acid 
or acetone is heated with an excess of caustic alkali. In order 
to prepare it, an intimate mixture of one part of sodium 
acetate and four parts of soda-lime is made and then heated 
in a flask or tube of hard glass, or, still better, in one of copper 
or iron, until the gas is evolved. In this way, however, the 
formation of a certain amount of free hydrogen (according to 
Kolbe^ about eight per cent.), as well as of ethylene, cannot be 
avoided. This latter may be removed by passing the gas through 
U tubes containing pumice stone moistened with strong suN 
phuric acid. 

According to C. A. Brindley the best mode of preparation is 
to mix 750 grams of caustic soda dissolved in 800 cbc. of water 
with 750 grams of acetate of soda, and, when this is dissolved, 
to add 1,250 grams of coarsely-powdered quick-lime. The 
mixture is then evaporated to dryness, and afterwards gradually 
heated to redness in an iron bottle. In this way 125 litres of 
marsh giis are obtained. 

Methane is fonned from acetic acid according: to the following 
ecjuation : 

CII,.CO.ONa + NaOII = CII, + CO(ONa),. 

^ Vol. I. pages 608-10. 

- IVwoz, lUrue SciaUif. i. 51 ; Dumns, Amu Chiin. /7ii/j. Ixxiii. 02. 

* Aits/. Lrhrb, Org. Chrm. i. 273. 



SYNTHESES OF METUANE. 103 



In order to prepare it in the perfectly pure state, zinc methyl 
is decomposed \vith water. ^ 

Zn(CH3)2 + 2H0H = Zn(OH), H- 2CH,. 

The synthetic formation of methane is of great theoretical 
interest. Berthelot* obtained it thus by passing a current of 
sulphuretted hydrogen, saturated with the vapour of carbon 
disulphide, over ignited metallic copper, when the following 
reaction takes place : 

CS2 -;- 2H2S 4- 8 Cu = CH, -f 4 CU2S. 

By this means about one-fifth to one-tliird of the total 
hydrogen in tlie sulphuretted hydrogen is converted into marsh 
gas. In order to separate tlie methane, he agitated the 
gas with alcohol, in which, as has been stated, marsh gas is 
tolerably soluble. By warming the alcoholic solution the pure 
gas is driven off. 

Methane is also formed by submitting a mixture of hydro- 
gen and carbonic oxide gas to the action of electricity in an 
induction tube, round which the electricity passes : 

CO -I 3H, = CH, + H,0. 

After the induction current has acted for five hours, about 
6 per cent, of marsh gas is produced.^ Although methane can 
be produced in this way, it is decomposed into its constituents 
at once, when subjected to the direct action of the electric 
spark. This decomposition, however, is not a complete one. 
The action of the induction spark ceases after half an hour, the 
original volume does not become quite doubled,* whilst a certain 
proportion of acetylene is formed. This latter gas, together 
with naphthalene, Cj^Hg, is also formed, according to Berthelot, 
when methane is exposed to a very high temperature, a portion 
of the gas being at the same time converted into its elementary 
constituents. 

Like all the paraffins, methane is a very stable body, unacted 
upon by cold concentrated nitric acid, and even by fuming sul- 
phuric acid at a temperature of 150°. On the other hand, 
chlorine attacks it so easily that when the mixed gases are 

» FranklanJ, Phil Trans. 1853, cxUi. 417. 

« C<y7npt. llend. xliii. 236. 

^ lirodic, Proc, Ttoy. Soc. xxi. 245. 

^ Ruff and Hofmaim, uimi. Chan. Pharm. cxiii. ]*-IJ). 

VOL. III. O 



194 THE METHYL GROUP. 



exposed to the sunlight an explosion may occur with separation 
of carbon, whilst in diflfused daylight a series of substitution 
products is formed. 



METHYL ALCOHOL, 

CH3OH. 

127 Boyle, in his Sccjytical Chemist (1 GG 1), constantly insists 
upon the fact that bodies cannot be resolved into their ulti- 
mate constituents by means of fire, a view which was generally 
held at .that time, and one which was supported by a mass 
of strange experimental evidence, respecting the truth of which 
the cautious Boyle gives it as his opinion *' that he that hath 
seen it hath more reason to believe it than he that hath not.** * 
In particular he states that the volatile product obtained by 
the dry distillation of wood is not a simple body, but that 
it consists of an acid-, or acetous-, and an indifferent or an 
adiaphorous (from aSm<^opo9, iudifferont) spiiit, which latter 
he showed to be inflammable.^ These two products he sepa- 
rated as follows : " I took eight ounces of the rectified spirit of 
box (wooil), wherein the acetous and neutral spirit remained 
confounded, as they had been in the first distillation ; and 
having poured this upon a quantity of calcined coral, sufficient 
to satiate the acid corpuscles (which quickly fell to corrode it 
with noise and bubbles), we gently distilled it to dryness in a 
glass head and body, by which means we obtained of adiaphorous 
spirit but eight grains less than seven ounces and a haltV* 

It was not until the year 1819 that this S])irituous liquid again 
attracted the attention of chemists. C<din believed it to be 
acetone, whilst Dobereiner in 1821 stated that he found it to 
contain common alcohol. Upon this Taylor^ remarked that so 
early as 1812 he had examined this body, to which he had 
given the name of pyrol igneous ether, because it was a sub- 
stance which, althou^di it possesses great similarity with ordi- 
nary alcohol, still differs from this body, inasmuch as it does 
not yield sulphuric ether on treatment with sulphuric acid. 
This property was confirmed by Macaire and Marcet (1824), by 
Gmelin (1829), and by Liebig (1832). A complete investigation 

' Boylo, Ojtrra^ \. 4S6, f«K»tiiotc. 

' •*Nrw OhscrvatioiiB about the Adiaphorous Spirits of AV(kx1s and divrrs 
other bo<lic8,*' i^jM-ra^ i. 61 G. 
* Tillochs, Phil, Mag. Ix. 315. 



IVIKTHYL ALCOHOL. 195 



of wood -spirit was made, in the year 1834, by Dumas and 
Peligot,* who were the first to point out the striking analogy 
existing between this body and common alcohol, an analogy 
which has exerted a marked influence on the progress of or- 
ganic chemistry. 2 They gave to this compound the name of 
methyl alcohol (from $ii6v, wine ; i/Xi;, wood). Their analytical 
results, however, did not agree with those obtained by Liebig, and 
hence Berzelius suggested in 1839 that wood-spirit must contain 
diflferent bodies, and this supposition was soon confirmed. 

Methyl alcohol is also formed when wood is heated to the 
boiling-point of mercury, with an equal weight of caustic 
potash and a small quantity of water,^ as well as when wood 
is heated with water to a temperature of 200°.* It is also 
produced in the dry distillation of other organic materials, and 
is likewise contained in the products of the action of heat on 
calcium formate (CH02)2Ca.^ 

Methyl alcohol does not occur in the free state in nature, 
although the methyl ethereal salts are contained in a variety of 
plants. Thus, for instance, the wintergreen oil obtained from 
Oavltheria procumbejis, a plant indigenous to New Jersey and 
various other parts of the United States, consists entirely of 
methyl salicylate, CHgCyH^Og.^ This compound is also the chief 
constituent of the ethereal oils of other species of Gaultheria, as, 
for instance, the G, jnuictata and Icucocarpa, which grow on the 
top of the extinct volcanoes of Java," and also of the Andromeda 
leschcnanUiiy indigenous to the Neelgherry Hills.* The ethereal 
oils from the seeds of AnthriscAts cerefolium, Pastinaca sativa 
and Heraclcum giganteum, cont^iin the ethereal salts of various 
alcoholic radicals, amongst which small quantities of a methyl 
compound, probably methyl butyrate, occur.® 

128 Commercial Pr€2)aration, Methyl alcohol is prepared on 
the large scale from the aqueous liquid obtained in the dry dis- 
tillation of wood. This contains a variety of other compounds, 
together with methyl alcohol and acetic arid. The most volatile 

^ Ann, Chim. Phj/s. Iviii. 5 ; Lxi. 193. 
' Kopp, Ocschichie der Chemic. iv. 330. 
' Peligot, Ann. Chim. Phys. Ixxiii. 218. 

* Greville Williams, Chcin^ News, xxvi. 231, 293. 

^ Lieben and Patenio, Ann. Chim. Pharm. clxvii. 293 ; Frieilol ami Silva, 
Cirm.pL. Rend. Ixxvi. 1545. 

* Cahonrs, Compt. Jimd. xvi. 853 ; xxxix. 255. 

'' De Vrij, Pharm-. Joiirn. Trans. [3], ii. .'503 ; Brr. DcuUich. Chem. Ges. xii. 246. 
" Bron^hton, Pliarm. Journ. Trans, [3J, ii. 281 ; Kuhlor, Per. Deutsch, Chem, 
Gfs. xii. 246. 

* Gutzeit, Licbia^i Attn, clxxvii. 344. 

o 1 



1% THE METHYL GROUP. 



portions are first distilled over, and these repeatedly recti- 
fied over quicklime in order to remove as much as possible 
acetic acid, water, and tarrj' substances. The wood-spirit thus 
obtained contains together with methyl alcohol, acetone, allyl 
alcohol, methyl acetate, homologiies, and condensation products 
of acetone, together with oily bodies and other compounds. The 
pure alcohol is obtained by first heating with caustic soda in 
order to convert the methyl acetate into alcohol. The disagree- 
able smelling impurities are then destroyed by a weak oxidising 
agent, and the product subjected to a systematic fractional dis- 
tillation, for which purpose an arrangement is used similar to 
that employed in the rectification of common alcohol.* The pro- 
duct obtaine<l in this way, freed as much as possible from acetous 
and allyl alcohol, constitutes the wood-spirit of commerce. 

Methyl alcohol is now largely obtained as a by-product in the 
beetroot sugar industry. In this industry, as in the manu- 
facture of cane-sugar, large quantities of molasses or treacle 
remain behind after the whole of the crystallisable sugar has 
been withdrawn. These molasses are invariably employed to 
yield ordinary alcohol by fermentation. Now the juice of the 
beet as well as that of cane-sugar contains, in addition to the 
sugar, large quantities of extractive and nitrogenous matter, 
together with considerable quantities of potash salts. In some 
sugar-pnxlucing localities tlie waste liquor or spent-wash from 
the still.s, termed "vinasse** in French, is thrown away; but 
in France it has long b(?en the custom of the distiller to eva- 
porate these liciuids to <lryness and to calcine the mass in a 
reverbcratory funuice, thus destroying the whole of the organic 
matter, but recovering the alkaline salts of the beetroot. In 
this way 2,000 tons of carbonate of potash are annually pro- 
duced in the French distilleries. For more than thirty years 
the idea hiis been entertained of collecting the ammonia water, 
tar, gas, and oils, given off when this organic matter is calcined; 
but the practical realisation of the project has only quite re- 
cently been accomplished, and a most unexpected new field of 
chemical industry thus opened out through the persevering and 
sagacious labours of M. Camille Vincent ^ of Paris. In this 
pro<*ess the spent-wash, after evaporation, is submitted to dry 
distillation. The distillate consists of a complex mixture of 

* litr. Knttr. I'hfin. I ml. ii. 277. 

" Comjif. Rend, Ixwiv. 211; />V//. Sm'. Chim. [2], xxvii. IIS; Kxpos. I'liiv. 
1S7H, rnnl. Chilli. groiijM* ;'•, rbtsM* 47. 



PREPARATION OF METHYL ALCOHOL. 197 

chemical products, resembling in this respect the corresponding 
product in the manufacture of coal-gas. It is, however, dis- 
tinguished from this, and approximates in composition to the 
products of the dry distillation of wood, by containing not only 
ammoniacal salts, but especially trimethylamine, acetonitril,and 
methyl alcohol. The distillate having been neutralised by sul- 
phuric acid, is evaporated in retorts, when the two latter com- 
pounds distil over. The nitril is decomposed by rectification 
over lime into acetic acid and ammonia, and the distillate 
contains dilute methyl alcohol, which may be dehydrated by 
a second treatment Tvith caustic lime. 

The best commercial wcod-spirit contains about 05 per cent., 
the more common varieties 75 to 00 per cent, of the pure alcohol, 
whilst some samples may contain only from 85 to 40 per cent, of 
pure substance.^ Besides water, it contains acetone and other 
bodies. 

129 Preparation of pure Methyl Alcohol. In order to prepare 
pure methyl alcohol the method suggested by Wohler ^ is best 
employed. This consists in preparing from the commercial 
article crystalline methyl oxalate, (€113)2020^, a body which 
boils at 162'', is easy to purify, and is readily converted into oxalic 
acid and pure methyl alcohol by heating with w^ater. According 
to Erlenmeyer ^ this ethereal salt is best obtained by dissolving 
anhydrous oxalic acid in boiling w^ood-spirit. The crystals which 
separate out on cooling are then washed with water by means 
of a filter-pump, until the liquid which runs off does not 
give the iodoform reaction. It is then boiled with water in 
a flask connected with a reversed Liebig's condenser, in order 
to decompose the ethereal salt completely, for which purpose the 
ebullition must continue for at least three hours; an addition of 
caustic soda facilitates the decomposition. According to Carius,* 
methjl benzoate, CH^.C-H^Og, may be employed instead of the 
oxalate. This is obtained easily by saturating a solution of 
benzoic acid in methyl alcohol with hydrochloric acid, and then 
removing the more volatile ethereal product by distillation. 
The residue is washed with water and thou decomposed by 
heating with caustic soda. 

It has already been mentioned that the ethereal oil of the 
Gaultheriu prorvmhenji chiefly consists of methyl salicylate, 

* Bardj ami Rordet, Bull. Soc. Chim. xxxii. 4. 

* Ann. Chem. Phanu. Ixxxi. 37G. 

* K. Itep. Phnrm. ex. 209. * Ana. Chem. Pharm. ex. 209. 



198 TUE METHYL GROUP. 



CHyC-H-Oj, boiling at 224°. Tiiis was formerly employed for 
the preparation of pure methyl alcohol. As salicylic acid is 
now prepared on a large commercial scale, the artificial salt may 
be made use of instead of benzoic acid for the purification of 
wood-spirit. 

Purified wood-spirit, as we have seen., frequently contains 
acetone, a body boiling at 56°, or 9° lower than methyl alcohol. 
This compound may, however, be almost completely separated 
by fractional distillation, and the product thus obtained, termed 
in French methyltncs dc queue, easily yields pure methyl alcohol 
by converting it into methyl formate, CH3.CHO2, a body which 
boils at 32°, and which is readily decomposed by caustic soda.* 

Pure methyl alcohol obtained according to one or other of 
these methods may be distilled from a water-bath in order to 
remove the water with which it is mixed, and then allowed to 
stand over ignited carbonate of potash for a long time, and 
afterwards rectified over either freshly burnt lime or anhydrous 
potassium ferrocyanide. The product thus obtained still con- 
tains small (juautities of water which can only be got rid of by 
rectification over metallic sodium or phosphorus pentoxide. 

130 Properties, Pure methyl alcohol is a colourless mobile 
li([uid possessing a pure vinous smell similar to that of common 
alcohol and having a specific gravity of 081 42 at 0° (Kopp). 
The boiling point as given by various observers varies from 58°*G 
to 6C^'5. This is jwirtly to be explained by the fact that the early 
exi)erimenters operated upon an impure compound, and partly 
also because the substance retains water with the greatest 
avidity. The perfectly anhydrous compound boils, according 
to Dittmar and Stewart* at 55°1, whilst Kopp^ formerly found 
the l)oiling point to he 54^*0 to 55*^-2. The vapour density of 
methyl alcohol was lirst determined by Dumas and Pi'ligot, and 
found to be 112. 

Methyl alcohol is misi'ible with water in aU proportions, a 
contraction and consequent evolution of heat occurring, this 
Iwing greatest when the relation of caie molecule of methyl 
alcohol to three of water is preserved. On ignition it burns 
with a jMile blue flame, like common alcohol, which it alt^o 
resembles, inasmuch as it acts as a solvent for manv substances 
which arc insoluble in water, such ns fats and volatile oi's, 

* Kramer and (JioJ/ki, U*r. htuf-^h f'ftcm. Or^. ix. 11»:JS; Ikiidy hikI Ilonlet, 
/?*///. Sor, Chim. xxxi. 531. 

* f'hem. Xnrx^ xvxiii. :^'». ^ .fi/n. Chrm. Phftmi. xr'iv. 'Jb7. 



PKOPEKTIES OF METHYL ALCOHOL. 199 



camphor, resins, &c. The alkalis and various salts are also 
soluble in this menstruum, whilst bodies which do not dissolve 
in common alcohol, such as potassium carbonate, potassium 
sulphate, &c., are likewise insoluble in methyl alcohol. Potas- 
sium and sodium dissolve in methyl alcohol with evolution of 
heat and liberation of hydrogen. Crystals separate out from such 
solutions which consist of compounds of the corresponding 
methylate with methylic alcohol. The potassium salt possesses 
the composition CH3OK + CHgOH.^ These bodies are instantly 
decomposed by water, with formation of caustic potash and 
methyl alcohol. Anhydrous baryta dissolves in pure methyl 
alcohol with evolution of heat, and on evaporating the solution 
in a vacuum, crystals of BaO + 2CH4O are deposited (Dumas 
and Peligot). When thallium ethylate CgH^OTl, a liquid obtained 
by the action of ethyl alcohol on thallium is poured into excess 
of methyl alcohol, tliallium methylate, CH3OTI, separates out 
in the form of a white granular precipitate, which when ignited 
bums with a beautiful green flame. This compound is soluble 
in ether and alcohol, and is decomposed by water with formation 
of thallium hydroxide (Lamy). Anhydrous calcium chloride 
dissolves in methyl alcohol with evolution of heat. Six-sided 
tables of the compound CaCl^ 4- 4CH^0 separate out on cooling 
the concentrated solution. These are very deliquescent and 
quickly decomposed by water, but may be heated in dry air to 
] 00° without losing methyl alcohol (Dumas ani P(51igot). Hence 
this compound was formerly used for the purification of wood- 
spirit. "* The raw product was saturated with calcium chloride, 
and this then distilled on a water-bath until the excess of wood- 
spirit, acetone, and other easily volatile constituents had passed 
over. The residue was then heated with water and distilled, 
when the purified wood-spirit first came over, and this was 
afterwards dried as above described. Similar compounds with 
lithium an<l magnesium chlorides, containing respectively three 
and ^ix molecules of methyl alcohol to one molecule of metallic 
chloride, have been prepared by Simon.^ 

Purified wood-spirit was formerly employed instead of spirit 
of wine as a source of heat, and as a solvent for various gums 
and resins. At the present day it is very largely used in the 
manufacture of aniline colours, and it is important for this 

^ Wiedmaun and Schweizer, Jouru. Pr. CJum. xxiii. (i. 
- Kane, PhiL Mag. [3], x. 45, 116. 
'^ Ba-. Vcutsch. ('firm. OV.v. xii. 1281. 



200 THE MP:THYL GROUP. 



manufacture to be able to determine the quality of the com- 
mercial product by a simple method. If the substance should 
only contain water the matter is easy enough, for mixtures of 
methyl alcohol and of ethyl alcohol with water exhibit, as Deville ^ 
has proved, almost the same specific gravity for equal percentage 
mixtures, and hence tables made for the purpose of obtaining 
the strength of dilute spirit of wine may be employed for wood- 
spirit. Dup:*6 2 has also determined the specific gravity of dilute 
aqueous solutions of wood-spirit of various strengths. More 
commonly, however, acetone and other ketones are present, as 
well as water, in common wood-spirit, and this lowers the value 
of the commercial article, not only by dilution, but also because 
their presence acts prejudicially on the colour. For the purpose 
of analysing commercial wood-spirit it is usual to prepare methyl 
iodide from it, and determine from the quantity of this com- 
pound obtained, the value of the methyl alcohol. This metho<l, 
first proposed by Krell,* has been worked out by Kramer and 
Grodzki,* as well as by Bardy and Bordet.^ 



METHYL OXIDE OR DI-METHYL ETHER, 

131 This compound was first prepared in 1885 by Dumas and 
Peligot ® by heating the alcohol with sulphuric acid, and termed 
by them hydrate of methylene. Ebelmen ^ afterwards showed 
that boron trioxide may be employed instead of sulphuric acid. 
It was then supposed that methjl oxide was formed by the 
withdrawal of the elements of water from the alcohol. This, 
however, is not the case, as will be afterwards explained (see 
Etherification, under " Ethyl Ether "). 

In onler to prepare this compound, a mixture of thirteen 
parts of methyl alcohol an<l twenty of sulphuric acid is gently 
heated to a temperature of 140** in a flask provided with a 
reversed condenser. The gtus which comes otf is washed 
through caustic soda in order to remove sulphur dioxide and 
carbonic acid, and then passed into sulphuric acid, which 
absorbs GOO times its own volume. It appears that in this 
case the comi>ouiul H.^S(\ + (CH,)^ or SO(OH)2(OCH3)2 is 

> Ann, Chim. Phfis. [3], v. 131». « Proc. Ro}i. Soc„ xx. 33i5. 

' Bcr, DcuUch, Chem, tha, 187^. l.Jlo. * Jhi,l. 1874. 1493. 

» /;«//. Soc Chim. xxxii. 4. « Ann, Chim. Phys, [2]. Iviii. ]y. 

' Ibid, [3], xvi. 138. 



1)I-METIIYL ETHER. 201 



formed. This may be preserved without alteration, and when 
it is allowed to drop into an equal volume of water methyl 
oxide is evolved.^ 

Methyl ether is now prepared on a large scale for the pro- 
duction of artificial cold. For this purpose one part of sulphuric 
acid is mixed with rather more than one part of anhydrous 
wood-spirit, and the mixture, which must be of specific gravity 
1'29, heated to a temperature of 125** to 128**, care being taken 
that the temperature does not rise above 130°. As soon as no 
more ether is evolved, the liquid is allowed to cool, and a suffi- 
cient quantity of wood-spirit added to the residue to bring up 
the specific gravity to 1'29. By repeating this operation, a large 
quantity of methyl ether can be obtained by the employment of 
a small quantity of sulphuric acid. The gas during its evolu- 
tion is washed by passing through caustic soda solution and 
over chloride of calcium, and being thus freed from carbonic 
acid, sulphur dioxide, and water, is then condensed to a liquid 
by pressure.^ 

Methyl ether is an agreeably smelling gas which, when 
ignited, burns with a bluish flame, and which maybe condensed 
by pressure or cold to a mobile liquid boiling at — 21° (Ber- 
thelot). Methyl ether is readily soluble in wood-spirit, spirit 
of wine, and common ether ; it is less soluble in water, which, 
however, absorbs at 18° about thirty-seven times its volume, 
acquiring a burning taste. If methyl oxide be brought in con- 
tact with dry hydrochloric acid in a freezing mixture, a colour- 
less mobile fuming liquid is formed which begins to boil with 
decomposition firom —3° to — 1"*, and which contains thirty-seven 
to thirty-nine per cent, of chlorine, nearly corresponding to the 
formula {CK^fi^ilCl.^ Water decomposes it instantly into its 
constituents. By the action of chlorine on this ether, substitu- 
tion-products are obtained, of which the first is monochlor- 
methyl ether, CHgOCHgCl, boiling at 59°-7, and the last 
perch lormethyl ether, (€013)20, a liquid which on heating 
yields tetrachlor-methano, CCl^, and carbonyl chloride, COClg. 

' Erlenmeyer and Kriechbaiimcr, DeiUsck, Chem, Oes. Bcr. vii., 699. 

' Tellier, Arch, Phann. x. 57. 

• Friedel, Cmnpt, Rerid, Ixxxi. 152. 



202 THE METHYL GROUP. 



ETHEREAL SALTS OF METHYL. 

132 Methyl CJUoride, CH3CI, was discovered by Dumas and 
Pcligot, who prepared it by heating a mixture of one part of 
wood-spirit, two parts of common salt, and three parts of 
sulphuric acid. The compound thus obtained is, however, not 
pure, but contains methyl oxide and sulphur dioxide. 

In order to prepare pure methyl chloride, zinc methyl is 
dissolved in double its weight of wood-spirit, and hydrochloric 
acid led into the boiling liquid contained in a flask furnished 
with a reversed condenser.* Methyl chloride is also obtained 
when the so-called basic cacodyl sesquichloride (Bunsen) and 
cacodyl dichloride (Baeyer) are heated. It is likewise formed as 
the first substitution-product when chlorine is allowed to act 
upon methane in diffused daylight (Dumas). 

It was formerly believed that the body obtained by this last 
process was an isomeride of methyl chloride, as it was said to 
exhibit a peculiar reaction with water. Bcrthelot,^ however, has 
shown that the substances obtained by these various processes 
are identical, and that the last preparation, like the chloride 
obtained in other ways, yields methyl alcohol when heated to 
100*" with caustic potash, whilst when treated with sulphuric 
acid and sulphate of silver or mercury, methyl sulphuric acid is 
formed, and this on heating with sodium acetate and acetic 
acid to 200"* yields methyl acetate. 

Methyl chloride has recently been obtained, as has been 
stated, on a large scale in the dry distillation of the beetroot 
" vinasses," which contains a large quantity of trimethylamine. 
This base is neutralised with hydrochloric acid and the con- 
centrated solution heated to 260^ when a regular evolution 
of methyl chloride and trimethylamine commences : 

:\ N(CH,\ CIH = 2CH3CI -h 2N(CH3)., -h CH3XH, + HCl. 

Tlie residue, which also contains hydrochloride of methylamine 
jis well as sal-ammoniac, is either worked up for the methyl base, 
or by heating it to 300**, mcjre methyl chloride can be obtained 
together with methylamine and ammonia. The methyl chloride 
thus obtained is si'paratcd from the alkaline compounds bv 

* (irovi'S, Jouiti, Chnn. So^-. r**74, 641. 



ETHEREAL SALTS OF METHYL. 203 



treatment with hydrochloric acid ; and after drying over calcium 
chloride it is condensed by pressure and preserved in cylinders 
made of strong wrought iron or copper. A mobile ethereal- 
smelling liquid is thus obtained which boils at —23°,^ and when 
ignited burns like other organic chlorine comjwunds, with a 
green bordered flame. Its specific gravity is as follows : 

At - 30° = 0-9990 
-25" = 9915 
- 0° = 0-9523 
-f 15° = 0-9247 

The tension of the vapour being : 

At 0^ = 2*48 Atmospheres. 
15° = 4 11 



20° = 4-81 


f} 


25° = 5-62 


}} 


30° = 6-50 


)» 


35° = 7-50 


>i 



The vapour density of methyl chloride was first determined by 
Dumas and Peligot and found to be 1 -736. Methyl chloride 
is only slightly soluble in water, but dissolves readily in alcohol. 
The neutral solution is not precipitated by silver nitrate. It 
forms with water at 6° a solid hydrate which separates out in 
amorphous flakes when the gas is led into cold water, but may 
be obtained in large crystals by the cooling of the aqueous 
solution. 

It has already been mentioned that methyl chloride obtained 
from marsh gas was formerly supposed to be an isomeric 
modification; this was not only because it was believed to 
be less soluble in water that the chloride obtained by other 
means, but also that it did not, like the latter, yield a hydrate. 
The observations upon which this conclusion was l)ased no 
doubt depend on the fact that by the action of chlorine upon 
methane a mixture is obtained which contains not only unaltered 
marsh gas, but also higher substitution-products. 

Methyl chloride is largely used for the preparation of various 
aniline colours, as well also as a means of producing artificial 
cold. For this latter purpose it will doubtless prove of great 
service both in the laboratorv and on the lar^^cr industrial 

^ Vin.f lit iiw\ D'^la«lianal, Bull. Sor. t'him. xxxi. 11. 



... -.r.' '.i\L i.;iiui:i'. 

^„.^; * .^lU'WfJ to escape from the receiver 
, vj;ni» to boil, and Ja a few moments 
.K- '.utuiU ia lowered by the ebullition to 
..i:.ji vmiut of the chloride. The liquid 
!iiv;ih of time in a (luiescent state, and 
v\Ainj{ agent. By increasing the rapidity 
m«>Uf« i>f a current of air blown through 
l'_\ pliu'htg the li<nii(l in connection with 




Km. fit. 

\ ^%- .\ III |<iiitil> 'h" It'iiiJoTiitiirp of the liquid can in n 
ii w mmm «n • I'l- n tini'i'il I" ■'''' i f ""' I'lrgo nina.io.'i of mercury 
. , .!^ miIl.IiIIoI rill' fiiiiBtriii'timi "f a small freezing m.ichino 
. iiiiiKw. .H\i M rmillli' Viui'i-nl is shown in Fig. CI. Itconsists 

I 1 ilmKI, i.iwil mi'iui' (I'.HHi'l, iN'twt'cn the two Citsings of 
vv'... It vl<«' iHi-ilnl ilil'iiili' I A) i;* int.r<Hlnce<l. The central sj^ce 

M* ..Hill. I will t" li.|iii'l H'irh tw alcohol, incai>nblc of w.Ii- 

.'...i „i.>n \'\w ilil.iiidi' lit' iiu'lhyl ii sillowi-d to enter from iU- 



METHYL CHLORIDE. 205 



cylindrical reservoir (P) by the screw tap (B), the screw (S) being 
left open to permit of the escape of the gas. As soon as the whole 
mass of liquid has been reduced to a temperature of — 23^ 
ebullition ceases, the screw (S) may be replaced, and if a tem- 
perature lower than —23** be required, the tube (B) placed in 
connection with a good air-pump. By this simple meaDs a litre 
of alcohol can be kept for several hours at temperatures either 
of —23** or — 55^ and thus a large number of experiments can be 
performed for which hitherto the expensive liquid nitrous oxide 
or solid carbonic acid was required. 

M. Yincent has recently constructed a much larger and more 
perfect and continuous form of freezing machine, in which, by 
means of an air-pump and a forcing pump, the chloride of methyl 
is evaporated in the freezing machine and again condensed in the 
cylinders. This enlarged form of apparatus will probably com- 
pete favourably with the ether and the sulphurous acid freez- 
ing machines now in use, as it can be simply constructed, and as 
the vapour and liquid do not attack metal and are non-poisonous, 
and the frigorific effects which it is capable of producing are 
most energetic. 

133 Methyl Bromide, CHgBr. Tins substance was first pre- 
pared by Bunsen,* by gently heating basic cacodyl super- 
bromide, as (CHj)^ (0H)2Br. It is a colourless gas which at 
—17^ condenses to a colourless liquid. Pierre * obtained it by 
acting with ordinary phosphorus on a well-cooled mixture of 
wood-spirit and bromine. According to him it is a sweetly 
smelling ethereal liquid which boils at + 13° and has a specific 
gravityat 0%f 1CG4. 

Amorphous phosphorus is now generally employed in this, 
as in the preparation of other bromides and iodides.' In 
this instance 133 grams of amorphous phosphorus and 
800 grams of methyl alcohol are mixed in a large retort sur- 
rounded by ice-cold water and furnished with a reversed con- 
denser. To this 800 grams of bromine is gradually added by 
means of a stoppered funnel After leaving the amorphous 
phosphorus in contact for several hours, the liquid is distilled, and 
the vapour condensed in a receiver surrounded by a freezing 
mixture. The product is washed with alkaline water and dried 
over calcium chloride. The bromide thus obtained has a specific 
gravity of 1*73 at 0° and boils at 4/5. Morrill explains the 

^ Ann. Chem Plunna. xlvi. 4i. - Jhu. ('htm. Phm. [31, xv 325. 

» Merrill, Jour.i. Pr. Chen. [2], xviii. 21^3. " 




20G THE METHYL GROUP. 



difference between his results and those before described, by the 
supposition that Pierre's compound contained water. 

Pure methyl bromide has a pleasant ethereal smell, resembling 
that of chloroform, and a burning taste. Its vapour density 
is 3*253 (Bunsen). When a flame is brought near the gaseous 
compound it bums with a greenish-brown, slightly luminous 
flame, giving off vapours of bromine and hydrobromic acid. 
When the source of heat is removed the flame is at once 
extinguished. It forms with water a white crystalline hydrate 
which does not exist above 4*" and probably consists of 
CH3Br + 20H2O (Merrill). 

134 Methyl lalide, CH3I, was first prepared by Dumas and 
Peligot by the action of iodine on common phosphorus and wood- 
spirit. This compound, like many iodides, easily undergoes 
double decomposition with other bodies, and therefore is largely 
used for the preparation of other methyl compounds. It has 
consequently been a matter of some importance to discover the 
most economical method of preparation.^ 

At the present day methyl iodide is prepared on a large scale 
by the use of commercial amorphous phosphorus. To a mixture 
of 35 parts of purified wood -spirit, 100 parts of iodine and 10 
parts of amorphous phosphorus are gradually added : 

10 CH3.OH + 5 I2 4- Po = 10 CH3I -f 2 P0(0H)3 -h 2 H2O. 

It is here seen that the phosphorus is in excess. A somewhat 
smaller quantity may be employed, but the excess appears to in- 
crease the rapidity of the reaction, and that which is not used 
can easily be regained. The mixture is allowed to stand over 
night, and then the methyl iodide distilled off, the distillate 
beinff washed with dilute caustic soda and dried over calcium 
chloride. Like the chloride and other methyl compounds, the 
iodide is largely employed in the manufacture of the various 
aniline colours. 

Methyl iodide is a colourless, powerfully refracting liquid, liav- 
ing a specific gravity of 2'20i) at 25"* and bailing at 42^" 5 (Linne- 
mann). Its vai)our density was found by Man-hand to be 
5*417.* It pissosses a |>eculiar ethereal smell, and on exposure 
to light turns brown from lil>enition c»f iodine. Whcjn heated 
with sixteen times its volume uf water for eight hours to 100^ it 

* Lindolt, ^Mw. CJinn. Pharm. Ixxxiv. 44 ; Hofmann, Quart. Journ, Chem, 
Soe. xiii. 69. 

• Journ. Frock. Chrm. zxxiii. 186. 



METHYL IODIDE. 207 



is decomposed with formation of methyl alcohol and hydriodic 
acid.' 

Methyl iodide can be inflamed only with difficulty, and bums 
when a flame is brought into its neighbourhood with a steel-grey 
coloured flame and with evolution of dense violet fumes of 
iodine. 

Methyl Fluoride, CH3F, was first prepared by Dumas and 
Peligot* in 1836, by heating potassium fluoride with potassium 
methyl sulphate. It is a colourless gas with an ethereal odour, 
which takes fire and bums with a blue flame with formation 
of hydrofluoric acid. 

135 Normal Methyl Sulphite, (CHg)^ SO3, is formed by the 
action of thionyl chloride, SOCU, on wood-spirit. It is a pleasant 
smelling liquid boiling at 121°'5 and having a specific gravity 
at Iff* of 10456.* Ebelmen and Bouquet found the vapour 
density to be 4*78. If a small quantity of caustic potash be 
added to its alcoholic solution, needles of potassium methyl 
sulphite, K(CH3)S03 are deposited. 

Hydrogen Methyl Sulphate, or Methyl Sulphuric Acid, 
H(CH3)S04, was obtained by Dumas and Peligot by mixing one 
part of methyl alcohol with two parts of sulphuric acid, when 
the mixture becomes hot and the following reaction takes place : 

CH3.OH + HgSO, = H(CH3)S0, + HgO. 

A limit is placed on the reaction by the formation of water, 
and for this reason the liquid always contains free sulphuric acid 
and methyl alcohol. In order to remove these, the mixture is 
diluted with water, neutrab'sed with barium carbonate, filtered, 
and sulphuric acid added to the solution until all the barium is 
thrown down. The filtrate, on evaporation in a vacuum, is said 
to yield methyl sulphuric acid in deliquescent crystals, although 
this statement is denied by Claesson.* He obtained the anhy- 
drous acid by allowing methyl alcohol to drop into chlorsulphonic 
acid cooled by ice : 

SO, I ^ + HO.CI-I3 =1 SO, I 2Jf J.J + HCl. 

The product, which contains eonie free sulphuric acid 
together with hydrochloric acid and methyl chlorosulphonate, 

' Xiedeiist, Lichiys Annalen, cxcvi. 349. 
2 Ann. Chim. Phys. [2], Ixi. 193. 

* Carius, Ann. Chew. Phann. ex. 219 ; 9x1. 97. 

* Joiirn. Pr. Chcm. N. F. xix. 231 



208 THE METHYL GROUP. 



S02Cl(OCH3), is an oily liquid which does not adhere to glass 
and does not solidify at —30*. If its aqueous solution be 
allowed to evaporate in a vacuum no crystals are obtained. 
On heating methyl sulphuric acid with methyl alcohol, methyl 
oxide is fonned, this substance being also produced, as has 
been stated, by the action of sulphuric acid upon the alcohol : 

Methyl sulphuric acid is monobasic, forming salts, most of which 
crystallise well. 

Potassium Methyl SuIpJiate, 2K(CH3)SO^ + HgO, forms deli- 
quescent monoclinic tables. 

Calcium Methyl Sulphate, Ca(CH3)2(SOj2» crystallises in 
deliquescent octohedrons. 

Barium MeHiyl Sulphate, Ba(OH3)o(SOj2 + SH^O, forms 
monoclinic tables and possesses a sweet taste. 

Lead Methyl Sulphate, Pb(CH3)2(SO^)2 + HgO, crystallises in 
long prisms ; it decomposes on heating into lead sulphate and 
normal methyl sulphate. 

Normal Methyl Sulphate, (0113)280^. This compound, which 
has also been called sulphuric methyl ether, was prepared by 
Dumas and Peligot ^ by distilling 1 part of methyl alcohol with 
8 to 10 parts of sulphuric acid. Acconling to Claessen,* how- 
ever, this method yields only a small product, as a large pro- 
portion of the alcohol is decomposed by the sulphuric acid 
with formation of sulphurous acid even when carefully heated. 
A better method is to heat anhydrous methyl sulphuric acid 
under diminished pressure to a temperature of 130° to 140**, 
when the sulphate distils over : 

2 H(CH3)S0, = H,SO, -f (CH3)2SO,. 

It is a colourless liquid possessing a smell resembling pepper- 
mint antl boiling at 187"* to 188°, undergoing slight decomposi- 
tion, but distilling unaltered in a vacuum. Its specific gravity 
is 1*327 at 18°. When heated with water it decomposes into 
methyl alcohol and methyl sulphuric acid, which on further 
boiling yields alcohol and free sulphuric acid. 

Methyl y it rite, CH3NO2, was first obtained by Strecker^ by 

* Ann. Chim, Vkm. Iviii. TA. ' Jottrn. /V. Cffm. X. F. xix. 243. 

' Ann. f'h'.in. Phtinn, xci. 70. 



METHYL NITRATE. 2C9 



heating wood-spirit and nitric acid together with copper or 
arsenic trioxide. The nitro^ren trioxide which is fonned acts 
upon the alcohol as follows : 

2 CH3.OH + N2O3 = 2 CH,.N02 + H^O. 

It is also produced when nitric acid acts upon brucine. It is 
an ethereal-smelling gas, which condenses at a low temperature 
to a colourless liquid boiling at — 12^ 

136 Methyl Nitrate^ CH3.NO3. According to Dumas and 
Peligot * this ether is formed in small quantity by heating nitric 
acid and methyl alcohol. A larger yield was obtaine<l by adding 
a freshly-prepared mixture of sulphuric acid and wowl-spirit to 
saltpetre, the heat evolved in the reaction being sufficient to 
vaporize the compound. The product obtained was, however, not 
pure. It began to boil at 60**, whilst the portion coming over 
at 66° possessed approximately the composition of the nitrate. 
That it chiefly consisted of this substance is s^.*en by the fact 
that on the addition of alcoholic potash, cr)stals of nitre were 
rapidly formed. Carey Lea,^ however, could not obtain methyl 
nitrate in this way. He succeeded in preparing it by employing 
the method suggested by Millon for the prejiaration of ethyl 
nitrate. Nitric acid alone acts chiefly as an oxidizing agent 
with formation of nitrous fumes, and converts the alcohol into 
nitrite. This action is, however, avoided by the addition of 
urea, which at once destroys the nitrous acid formed. In order 
to prepare methyl nitrate, 150 cc. of pure nitric acid, having a 
specific gravity of 1*31, are brought into a retort together with 
40 grams of nitrate of urea, and to this 200 cc. of methyl 
alcohol are added and the mixture carefully distilled to one-third, 
130 cc. of nitric acid and 170 cc. of wood-sjnrit are then added, 
and the mixture again distilled to one-third, and at last 
10 grams of nitrate of urea, 110 cc. of nitric acid, and 150 cc. 
of methyl alcohol, and this is again distilled to one-third. The 
distillates are then mixed and shaken up with a solution of 
common salt, the ether which separates out being washed with 
a dilute solution of potassium carbonate. Methyl nitrate is 
also easily obtained by adding 2 parts of a cold solution of 
methyl alcohol and sulphuric acid to a cold mixture of 1 part 
of nitric acid and 2 parts of sulphuric acid. 

' Ann. Chim, Phys. Iviii. 37. 

* Sillitnan's Am/Journ. [2], xxxiii. 227. 

VOL. III. P 



tlj MEIIiYL O :-iU*_'l*M<5. 



Mibdiji iiiuaie ia a liqiiid of an eih^real odoor, wLkrh at ^O"" 
ha^ a specific gravinr of 1'1^± Wken ignhe*i it boms with a 
bright Te:IloT dame, azid its vapc^nr exploJes when heated aboTe 
150' with such f.rce that a cast-iroa bc*iler, in which a glass 
hailrxm containing 2>>0 ca of vap>ar was placed, was fractured 
bj the explosion ; whikt Dumas and Pcligc*t f^ond that when a 
flame waa bronaht u* the month of a glass bolb containii^ the 
rapoftir placed in a {Matintim crucible, not onlv was the bulb 
broken but the platinum crucible was torn to piecesL The 
hqaid abo detonates on percussion. If a piece of filter paper 
be impregimted with the liquid and then struck with a hammer 
on an anvil, an explosion takes place as violent as that caused 
by nitro-glycerin /Girard). 

Carey Lea, in 1S62, showed thai this cMupound may be used 
instead of the much more expensive iodide of methyl in the 
preparation of io^line^violet and iodine-green, and for a long 
time it was employed for this purpose. It is, however, no 
\iA%%*:x UiM^d, owing to the series of &tal explosions which have 
ft^milietl from its employment. 

137 liuMphUe of Mflhifl. As yet only the methyl phosphorous 
add P(0H;2^0CH^ ia known. This is obtained by acting on 
nf^;thyl alcohol with phosphorous trichloride and forms a syrupy 
\*:Ty add liquid which cannot be prepared in the anhydrous state 
an on h«;ating it decompr^ses into alcohol and phosphorous acid. 
It j» monobaiiic ami forms a series of salts which have been 
ofily iilj;(htly investigated.* 

J'hjHphatfH of Mdhyl. The orthophosphate, P0(0CH3)j, has 
not \fiii'.u prejifircd. When phosphorous oxychloride acts on 
meth)l ftlcohol, bibasic methyl phosphoric acid, P0(0CH3)(0H)j, 
ati/J mowjUiti'ic dimethyl phosphoric acid, PO(OCH3)2(OH), are 
{onut'A, VjittU of these yields a series of salts investigated by 
Belli ff.' Tlio free acids are only known in solution as thick 

ar'irl ItqiliflM. 

AfrfJit/l ArscniU, As(OCHj)g, is obtained by the action of 
mxUxiui ethylatr* on arsenic tribromide, in the form of a liquid 
wliii'li Uiiln at 128" to 129^ and is instantly decomposed by 
Wttt^jf iiiUi tirmnic trioxide and methyl alcohol. 

Mdlii/l Artie fuUt\ AsO(OCH3)3, is obtained by the action of 
methyl iodide on silver arsenate. It is a liquid which under- 
gocM |Kutiai d(f('oiii[>o8ition on distillation between 213° and 

' Srhirr, ^Inn. Chnn. PItann, nu. 104. 
• .tun. Chrm. I'futrm. cii, 3U4. 




SALTS OPMETHVL. 211 

faCttuia without decompositioB. 
arsenic acid and methjrl 

E normal ether, or methyl ortlio- 

1 by Ebelmen and Bouquet ' by 

ide into wood-spirit. The samoconi- 

len pure anhydrous methjl alcohol is 

toxide.' It is a powerfully-smelling liquid, 

nviiig a specific gravity of O-i at 0°. When 

with a very britliant green-colon red flanie, 

t ibun that of the corresponding ethyl compuund. 

B preferable to use wood-spirit instead of cointnon 

ting for boric acid. 

I Borate, BOjCHj, ia also formed by the aclioii 

iotide ou methyl alcohol, together with the normal 

"his ia a syrupy Dquid which also bums with a bright 

I fiamc and decomposes on beating into the orthu-ctliur 

tagUissj residue consisting of the compound B^OnCHj. All 

ethers decoTnpnsc water with formation of methyl alcohol 

aad boric acid, and for this reason methyl orthoborate becomes 
turbid on exposure to moist air. 

139 Methyl Ortkomllmie, Si(OCHa)^, is formal by the action 
of silicon tetrafiuoridc on anhydroua methyl alcohol. It ia u 
liquid of ethereal odour, boiling at 120° to 122° and having a 
specific gravity at 0° of 10589. It is tolerably readily solublo 
in water, gelatinous .tilicic acid separating out from the solution 
after some weeks. If afjueoua methyl alcohol be employed in 
the above reactions ethyl disilicato, SijOfOCHj)^, is formed. 
This ia also a pleasantly-smelling liquid, boiling between 201" 
and 202°- .), and having a specific gravity at 0° of 11441,* The 
vapour density is 919. 

140 Curlonntci of Methyl. The normal ether {Cll^fiO^ has 
not yet been prepared. If a solution c f anhydrous baryta in 
methyl alcohol be treated with carbon dioxide a precipitate of 
pearly plates separates out This consists of barium methyl 
carbonate, Ba(CH3).,(COs)2, easily soluble in cold water. This 
solution gradually decomposes in the cold and more quickly on 
Iieating, with formation of barium carbonate, methyl alcohol, 
and carbon dioxide (Dumas and Peligot), 

' Cnifta, BulL Soc. Chem. xiv. 89. 

» Ann. Chim. Phgs. [3], xvii. 50. 

'■' H. Schiff, Aim. Chtm. PAarm. Suppl. Bd. *. 16*. 

' Bull. Soe. Chim. [2], ui. 836. 



iV2 METHYL CO^IPOUNDS. 



By iictii»c^ on methyl alcoliol with carbonyl chloride, methyl 
chlorocarbonate is formed : 

CO I ^[ + HO.CH3 = CO I ^^^ + HCl. 

This is an irritating-smelling liquid which is insoluble in water, 
but gradually decomposes in contact with this into carbon 
dioxide, hydrochloric acid, and methyl alcohol. 

Methjjl Carbamate, or Methyl Urctlcane, CO ■! Qp A • This was 

first obtained by Dumas and Peligot by dissolving the fore- 
going compound in aqueous ammonia. It is likewise formed 
by passing the vapour of cyanic acid into methyl alcohol.* In 
order to explain this reaction we must assume that the unstable 
cyanic acid decomposes into an isomeric carbimide and this acts 
as follows on the alcohol : 

N I ^g + HO.CH, = N I CO.OCH3 

Methyl carbamate is also obtained by acting on methyl alcohol 
with cyanogen chloride.'- It easily crystallizes in large deli- 
(luescont tables which melt at oo", and the liquid boils at 177'. 

Mdhyl AUo2fha?mte, NH -j nQQnjj » is also formed together 

V. 3 

with uretliaue by the action of cyanic acid on wood-spirit. This 
c<»nip:)UTid stands in the same relation to biuret asurethane does 
to nrra. It is difiicultly soluble in water and crystallizes in 

n(.'tMlK\s, 

Methyl Thiocarhonatey (0113)2083, is a yellowish disagreeably- 
smelling liquid boiling at about 250'' and is obtained by distilling 
concentrated solutions of calcium methyl sulphite and potassium 
tliiociibomiti' (CJahours). 



SULPHUR COMPOUNDS OF METHYL. 

141 Mdhyl Hydroaulphide or Methyl Mercaptan, CH3.SH, was 
dis*c»vercd by Dumas and Peligot, who obtained it by heating 
jH)tassium hydrosuljJiide with methyl sulphate. It was after- 
wurds more thoroughly examined by Gregory,^ who prepared it 

* Lkbi;; ami Wiihlff, Jnn, ("hem. Pharm, liv. 870; rifihanit and I.aureiit, 
i'finftt. JUiul. xxiii. 4r»7 ; l^icbif?, Ann. f%'M. Pharm. Iviii. *iO«>. 
- Kilu'varri;!, IhiiK Ixxix. IIU. ' Amu Phiirm. xv. 23i». 



SULPHUR COMPOUNDS OF iMETHVL. 213 



by distilling concentrated solutions of potassium hydrosulphide 
and potassium methyl sulphate. It is a colourless unpleasantly- 
smelling liquid, boiling at 2V and quickly uniting with mer- 
curic oxide to form mercury methyl mercaptide, (CH3S)2Hg, 
a compound which crystallizes from hot alcohol in glistening 
white plates. 

Methyl Sulphide, (CHj)^^. In order to prepare this substance, 
Begnault * recommends a solution of caustic potasli in methyl 
alcohol to be divided into two nearly equal parts. The smaller 
of these is saturated with sulphuretted hydrogen and then 
mixed with the other part, so that potassium monosulj^hide 
is formed together with a little free potash but no potassium 
hydrosulphide. This solution is then saturated with gaseous 
methyl chloride, the solution gently warmed whilst the gas is 
being passed in, and the volatile product collected in a reservoir 
surrounded with ice. The distillate, which consists of a mixture 
of methyl sulphide and methyl alcohol, is next washed with 
water which dissolves the alcohol, the sulphide remaining in- 
soluble. This latter is again repeatedly washed with water, 
and at last dried over calcium chloride. 

Methyl sulphide is a colourless mobile liquid possessing an 
extremely unpleasant odour. It boils at 41°, and has a specific 
gravity of 0*845 at 21°. When allowed to drop into dr}^ chlorine 
gas it takes fire and bums with a red flame with separation of 
carbon. Substitution-products are however formed by a more 
gradual action of chlorine, the last of which, perchlormethyl 
sulphide, (€013)28, is a red liquid which decomposes on heating.^ 
Methyl sulphide combines with mercuric chloride, mercuric 
iodide, platinic chloride, and other haloid salts, and these 
compounds can be obtained beautifully crystallized from hot 
alcohol.^ 

142 Dimcthyl'Sulphinc Compounds, Methyl sulphide combines 
directly with bromine to form the dibromide, (CH3)2SBr2, a 
compound which crystallizes from water in amber-yellow octo- 
hedrons. If methyl sulphide be dropped into well-cooled fuming 
nitric acid, and the solution allowed to evaporate, colourless 
deliquescent needles of the nitrate, (CH3)2S(OH)N03, are 
obtained. If these are decomposed by barium carbonate, or if 
the bromide be decomposed by freshly precipitated oxide of 

1 Ann. f'him. Ph^/s, [2], Ixxi. 391. 

- Kiche, Ann. C/um. rhi/s. [3]. xliii. i.'l)2. 

3 Loir, JhU/. xxxix. 448 ; liv. 42. 



MKrilYL a>MPOUNDa 



ix... linu I.IIW .lul^khtno oxide, (0113)280, is formed. This is 
...ivtUi >>4 \\.«tv t iuul alivhol, and on evaporation and cooling 
...ivliii* ' u* i I vkKauU\>4 and inodorous mass. If the nitrate be 
U, .l^ I ».» \00 . vlnuothvl-sulphone (0113)2802. is formed. This is 
..^•iviM\ Lu waUu uud nitric acid, and crystallizes from the latter 

MUtUt>u lu ^m.^inaft which melt at 109'^ although at lOO"" they 
l«. >;u» 1^1 wiliitiliao. The liquid boils at 238°.* 

I U i\i fHi i/ij/isiitph ine Compoxnids} Methyl sulphide combines 
w i*liU vMth UKthyl iodide to form (0113)38!, a compound crys- 
i.tlti \\\., \\^^\^\ ui)U(H»us Holution in large colourless prisms, and 
III nil aUohiil iu rh(tn)bic tables which soon become brown on 
,i^|miikii> til uii'. It is also formed when the sulphide or 
iti* lut u-4i'tuh irt htwited to 100'' with hydriodic acid : 

^1) li^CUg^S + HI « {0H3)3SI + OH38H. 

[±) :um3.sH + HI = (CH3)3Si + 2H2S. 

h 1.1 likuwirto obtained by the action of methyl iodide on 
tui lit.J ihiocyunate. 

liu'. iiiilidi) is decomposed by moist silver oxide with forma- 
\yKx\\ ul tiiiiiothylsulphine hydroxide, (OH3)3SOH. The solution 
ti( ikiia v'on))M)und is strongly alkaline, and on evaporation yields 
\\i^K\ ^bu as an oil having the smell of an isonitril.^ On neu- 
V« \luUiou with acids a series of trimethylsulphine salts are 
■ll iikual, hiimo of which may be prepared by the action of silver 
^11 1 MM iUm iodiile (Letts). The chloride crystallizes in de- 
l^iMt' •tv-^tl' I'li'^HiH, and combines with platinic chloride to form 
S\\v \l»»ultlM »-*»lti -(,<'H3)3SC1 + PtCl4, crystallizing from boiling 
\y\\\\ \\\ ^lillti^Mnh red combinations of the cube and octohedron. 
\\\\. \\\v l"««i» li»|»idly absorbs carbon dioxide, giving rise to a 
M wii^'i**^'' iiiiimiuilM. Its solution readily absorbs sulphuretted 
Iml^m^^u \\\\\\ liirnmtitin of the hydrosulphidc, S'OHjijSH, 
\\\\\\\\ \'<hil'H*i till Hm* reactions of the hydrosulphidos of the 
\\\\U\^ II *'»»' hyilioxido be added to this solution, trimethyl- 
A\\y\\\\\v ».Ml|i|ihhs hOllaljSJjS, is produced. This solution 
\lu \u\^H»**4 »• »»H i'nni'0Mliiiti«>n with formation of three molecules 
A \\\\\\\\\ »«mI|»I«I«I»v '!''»** nqueous solution of the sulphide 
\\\\\U \\\v rhHM»*t»'» !»•<••' H'lirtions of the sulphides of the alkali 
\\\\\^\\^ rhu« n- dl"ii"lv«'n antimony trisiilphido, is coloured 

» ^\\\\\\ 4*«'» •'*'**• /•*•!» »•■ «'»Jiv. 148. 

\ .,l..iui.' **».'.* ■> • •■'•»"• r-l« i^- ^*' 5 -'''''• '''*""■ ^^"^' ^'^' ^' ^^' ^*'^'°» 



METHYL SULPIIOXIC ACID. 215 



deep violet by sodium nitropnissido, and is decomposed by acids 
with evolution of sulphuretted hydrogen.* 

Melhyl Disxdphide, (CH3.)oS2, is obtained by acting on methyl 
chloride with alcoholic solution of potassium disulphide. It is 
a yellowish unpleasantly-amelling liquid boiling at 11 2^ It is 
likewise obtained by employing a higher sulphide of potassium, 
when the trisulphide of methyl is formed at the same time. 
This body closely resembles the disulphide, but boils at 200"*. 

144 Methyl Sulphonic Acid, CH3.S()j,H. Tliis aci<l was dis- 
covered by Kolbe ^ in 1845, and originally termed methyl liypo- 
sulphuric acid. Berzulius and Marcet had found in 1813 that 
carbon disulphide on treatment with moist chlorine yielded the 
compound CCl^SOg, to which substance they gave tlie name of 
sulphite of chloride of carbon. Tnis is also readily obtained 
bv treating carbon dioxide with hydrochloric acid and manganese 
dioxide, and is, as Kolbe showeil, trichlorniothyl sul})honic 
chloride, CClj.SOgCl. If this is heated with baryta water, barium 
trichlormethyl sulphonate,(CCl3 S03)2Ba,is produced and the free 
acid can easily be obtained from this as a white deliquescent mass. 
It is easily reduced by nascent hydrogen, one atom of chlorine 
after the other being replaced by hydrogen, and thus methyl 
sulphonic acid is formed. The same substance is i)roduced 
when methyl mercaptan, methyl disulphide, or methyl thiocya- 
nate is heated with nitric acid. On evaporation on the water- 
bath the acid remains as a thick syrup w^hich still may contain 
some free sulphuric acid. In order to obtain the pure acid, the 
barium salt is decomposed with sulphuric acid, or the lead suit 
with sulphuretted hydrogen. This substance has not been 
obtained in the crystalline state, but only as a strongly acid 
thick colourless inodorous liquid, which when heated above 130** 
becomes brown and begins to decompose. It may be boiled with 
ordinary nitric acid without undergoing change, and chlorine 
even in the sunlight does not act upon it. Its salts arc all 
soluble in water .and almost all crystalline. 

Potassium Methyl Sulphonale, CH3.SO3K, is not only formed 
by neutralizing the acid with potash, but also by heating methyl 
iodide with an aqueous solution of normal potassium sulphite. 
It is easily soluble in water, and crystallizes from hot alcohol in 
finely interlaced threads. The double compound, CH3.SO.K -f 
CH,^.S03H, separates in deliquescent prisms when a mixed 

^ Cniin-Brown an«l lilaickio, Ch^m. Knrny xxxvii. 130; xxxix. fil. 
- ^tinu Cht'm. I'll It nn. liv. 174. 



21G METHYL COMPOUNDS. 



L 



solution of the sulphonate and of the free acid is placed in a 
vacuum over sulphuric acid. 

Barium Methyl SidplvancUe, (CH3.S08)2Ba + H^O, forms 
fine transparent rhombic tables which are unalterable in 
the air. 

Lead Methyl Sulphonate^ (CH8.S08)2Pb+H20, crystallizes in 
large prisms, also unalterable in the air. 

Silver Methyl SulpJionate, CHg-SOjAg, forms fine transparent 
tablets which have a sweet metallic taste, and remain unaltered 
on long exposure to the air. 

Methyl StUphonw Chloride, CHj.SOgCl, was obtained by 
Carius ^ by acting on the acid with phosphorus pentachloride : 

SO2 1 q2» H- PCI5 = SO2 1 gf^3 + POCI3 + HCl. 

It is a powerfully-smelling liquid boiling at 150'' to 153^ It is 
slowly decomposed by water into hydrochloric acid and methyl 
sulphonic acid. On heating with phosphorus pentachloride to 
150'-1G0°, the following reaction occurs : 



SO 



)CH 



, I ^p + PCI5 = SO.Cl + CH3CI + POCI3. 



SELENIUM COMPOUNDS OF METHYL. 

145 Methyl Selenide, (0113)280. By distilling a solution of 
potassium methyl sulphate with potassium selenide, Wohler and 
Dean obtained a reddish-yellow highly offensive liquid which, 
until recently, was held to be the above compound. It is, 
however, most probably the diselenide. Methyl monoselenide 
is obtained by heating potassium methyl sulphate with caustic 
potash and phosphorus pentaselenide : 

P^5 + 10 K(CH3)S0, -h 16 :\aOH = 
6 (CH^^Se + 5 K^O, -f- 5 Na,SO, + 2 Na3P0, -h 8 H.O. 

It is a ooIourlefB strongly refracting liquid, heavier than water, 
possessiiig a most unpleasant smell, and boiling at oH'''2. It 
decomposes in contact with water in the cold, and more quickly 
on bailings with separation of selenium. 

* Jhh. Chcm, Pharm. cxiv. 140. 



TELLURIUM COMPOUNDS OF METHYL. 217 



MethyUeleni-nitratey (CH3)2Se(N03)OH, is formed by dissolv- 
ing the selenide in strong cold nitric acid. It crystallizes out 
from water in long prisms, melting at 90°'5, and volatilizing 
below 100^ 

Methylsekni'dichhruh, (CH3)2SeCl2, is precipitated by hydro- 
chloric acid from a concentrated solution of the nitrate. It 
crystallizes from alcoholic solution in mother-of-pearl scales, 
which have an unpleasant smell, and melt at oO^'S. 

The corresponding bromide and iodide are known, and also 
mcthylseleni'platinie chloride, 2(0113)280 + PtCl4, obtained by the 
direct combination of its constituents, and crystallizing in yellow 
feathery needles from alcohol.^ 

Methyl Scleiwnic Acid, CHj-SeOgH, is obtained by oxidizing 
the diselenide with nitric acid. It crystallizes in prisms which 
melt at 122^ having an unpleasant smell and a metallic taste. 
It forms a series of crystalline salts.^ 



TELLURIUM COMPOUNDS OF METHYL. 

146 Methyl Telluride, (€113)2X6, was obtained by Wohler and 
Dean' on distilling potassium tellurido with a concentrated 
solution of potassium methyl sulphate. It is a light-yellow mobile 
liquid which boils between 80° and 82^ yielding a yellow vapour, 
and has a very unpleasant garlic-like odour, which is so per- 
sistent, that when working with the substance the breath 
becomes persistently tainted with tlie smell. 

Methyl Tellurium Oxide, (CH,)2TeO. Methyl telluride dis- 
solves in strong cold nitric acid with the formation of the 
nitrate, (CH3)2Te(N03)OH, which crystallizes in large colourless 
prisms. Hydrochloric acid throws down the chloride, (CH3)2TeCl2, 
from this solution, in the form of a thick white precipitate, 
which crystallizes from solution in hot water in long thin 
prisms. When heated with water and freshly precipitated 
silver oxide, a solution of the oxide, or more probably of 
the hydroxide, (0113)2X0(011)2, is obtained. A distinctly crys- 
talline mass is produced on evaporation which deliquesces on 
exposure to air, and absorbs carbon dioxide. It possesses a 

^ C. T-,oriD*? Jackson, Liehitfs Avualrn^ clxxix. 1. 
- AVbhlcr and Dean, Ana. Chcm. r/uinn. xcvii. t). 
' Ibid, xciii. 233. 



218 METHYL COMPOUNDS. 



most unpleasant taste, but is odourless. Its solution turns red 
litmus-paper blue, and it liberates ammonia from sal-ammoniac 
at the ordinary temperature, and gives a blue precipitate with a 
solution of copper sulphate. 

Sulphur dioxide precipitates methyl telluride from its 
solutions : 

(CH3)2TeO + SO2 + H.O = (CH3),Te + H^SO,. 

The oxide forms, with acids, salts which have been examined by 
Wohler and Dean, and also by Hceren.* They are, as a rule 
soluble in water, and crystallize well. 



NITROGEN BASES OF METHYL. 

METHYLA^nNE, N(CH3)H2. 

147 Methylamine was discovered by Wurtz,^ in 1849, who 
obtained it by the action of caustic potash on methyl isocyanato, 
or isocyanurate (see p. 225). Hofmann ^ then prepared it by 
heating methyl iodide with ammonia, and Carey Lea,* as well 
as Juncadella,^ showed that it is also easily obtained when 
methyl nitrate is used instead of the iodide. This base is also 
formed by various other reactions, of which the following are 
the most important. 

Mendius^ found that methylamine is pro<luced when hydro- 
cyanic acid is acted upon with dilute sulphuric acid and zinc ; and 
Debus" showed that it is likewise produced when a mixture of 
hydrogen with the vapour of hydrocyanic acid is jjassed over 
platinum bhick heated to 110°; again Bert helot® obtained it 
by heating methyl alcohol with ammonium iodide to 100^ cr 
with sal-amnxmiac to 3()0^ According to Dusart and Bardy,*^ 
only a small quantity of the base is formed when sal-ammoniac 
alone is utod, but if hydrochloric acid be added, and the mix- 
ture heat<?d for thirty hours to a tem]H>rature of 20o*'-20S'*, :i 
better yield is obtained. On the other hand, "VVeith ^^ found 
that when an excess of methyl alcohol is employed, the sal- 
ammoniac can be completely methylateti. On heating two 
grams of this salt with 12 cbc. of pui*e methyl alcohol 

' CTirm. Centra^b, ISOl, OIG. • Ann. Chim. Phys. [3], xxx. WW. 

» PhU, Tmn». 1851. p. 381. * Chfm. JNVir«. vi.'48. 

* OmpL Rend. zItiu. 342. * Ann, Chfm, Pkarm, rxxi. 130. 

' GUm, Soe. Joum. xvi. 240. • Ann. Chim. Phyn, [3\ xxxviii. CO. 

^ roM|if. Bemd, Iiiiv. 180. >* Ber. JkuUeM. Cktm, O*. viii. 45S. 



METHYLAMINE. 219 



to 280°-285'' for ten liours, methyl ether, hydrochloride of 
trimethylamine. and tetramethylammonium chloride were 
formed. On heating three grams of sal-ammoniac with 12 
cbc. of methyl alcohol for six hours to the same tem- 
perature, hydrochloride of methylamine was obtained in 
addition to the above compounds. 

Methylamine occurs in nature in Mereurialis annua and 
Af. perennis,^ being formerly known in the impure state as 
mercurialine. It is also found in herring brine, and occurs 
frequently as a product of the decomposition of the alkaloids, 
and similar compounds. It has likewise been observed by 
Anderson in the products of distillation of animal matter, and 
also of that of wood (Camille Vincent), and it is now obtained 
on the large scale in Vincent's process. It has already been 
stated (p. 202) that hydrochloride of trimethylamine decom- 
poses, at a temperature of about 285°, into methyl chloride 
and trimethylamine which volatilize, and hydrochloride of 
methylamine, which remains behind. This is always mixed 
with some sal-ammoniac, from which it may, however, be 
separated by solution in absolute alcohol ; the spirit is then 
distilled off, and the residual salt decomposed with caustic 
soda. 

Methylamine is a colourless gas condensing at a few degrees 
above 0°, to a mobile liquid which does not solidify on exposure 
to the temperature obtained by a mixture of ether and solid 
carbon dioxide. It has a strong ammoniacal, but also a slight 
fish-Uke smell, and is more soluble in water than is ammonia, 
which it resembles very closely. At 12°*5 one volume of water 
dissolves 1,150, and at 25^ 059 volumes of the gas. It is easily 
combustible, and may in this way readily be distinguished from 
ammonia. It burns with a bright yellow flame, forming water, 
carbon dioxide, and nitrogen. If an insufficient supply of air be 
present, small quantities of cyanogen and hydrocyanic acid are 
also formed. Tins latter compound is produced, together with 
ammonium cyanide, when the gas is led through a red-hot tube 
filled with pieces of porcelain. When it is heated with potas- 
sium, potassium cyanide is formed, with evolution of free 
hydrogen. 

Like ammonia, the aqueous solution precipitates many 
metallic salts, and these precipitates partially dissolve in an 
excess of the reagent. Silver chloride also dissolves in excess 

' Schmidt, Licbig's Ann. cxciiL 73. 



220 METHYL COMPOUNDS. 



k 



of inetbylamine. On the other hand, the hydroxides of cadmium, 
nickel, and cobalt do not do so, and these reactions serve as 
another means of distinguishing it from ammonia, and in addi- 
tion we have the fact that aluminium hydroxide dissolves in 
methylamine but is insoluble in ammonia. 

Hydrochloride of Meihylamin4^ or Jdctftyl-ammonium Chloride, 
N(CH3)H3C1, crystallizes from alcohol in large iridescent tablets 
which deliquesce on exposure to moist air. It forms with gold 
chloride the double salt N(CH3)H3Cl + AuCl3+H20, which 
crystallizes in splendid large golden yellow needles, whilst the 
platinum salt, [N(CH3) H3Cl].,PtCl4, forms golden yellow scales or 
large hexagonal tables, soluble in water but insoluble in alcohol. 

Sulphate of Meihylamiiie or Methyl-am monium Sidplvatc, 
[N(CH3)H3l2SO^, is easily soluble in water but insoluble in 
alcohol. It crystallizes in deliquescent stellar needles. It 
forms an alum with aluminium sulphate, [N(CH3)H3]2SO^ + 
Al2(SO^)8+24H20, which crystallizes in large regular octo- 
hedrons. 

Nitrate of Methylamine or Methyl 'ammonium Xttrate, N(CHg) 
H3NO3, forms orthorhombic prisms which are deliquescent and 
easily soluble in alcohol. 

Carbonate of Methylamine or McthyUammonium Carhoimte, 
[X(CH3)H3]2C03, is produced on distiilation cf a mixture of 
calcium carbonate and hydrochloride of methylamine. It has, 
however, not yet been obtained in the pure state. It forms 
hard prisms which are very deliquescent, has a strongly alkaline 
reaction, and undergoes volatilization at the ordinary tem- 
perature of the air. At the s^inie time, methylanimonium- 
methylcarbamate is formed. This also is ]>roduced by the 
direct union of methylamine and carbon dioxide. 

With platinous chloride, methylamine forms several com- 
pounds corresponding to certain of the platinanmionias 
(Wttrtz). 

DlMETHYLAMINE, N(CH3)2H. 

148 This was discovered by Hofmann, who obtained it by 
heating methyl iodide with an alcoholic solution of am- 
rnonia^ when the hydriodides of ammonia, methylamine, 
dimethylamine, and trimethylamine, as well as tetra- 
methylamnionium iodide are formed. The last salt is, 
however, soluble in alcohol, and it, therefore, can be readilv 
Mparated from the other four. These are then distilled 



DI- AND TRI-METHYL AMINE. 221 



with caustic potash, and the vapours led into a well-cooled tube, 
when tiimethylamine, dimethylamine, and a portion of the 
methylamine are condensed, the remainder of the last-named 
substance passing forward with the ammonia, and being afterwards 
absorbed in hydrochloric acid. The mixture of the three bases 
is then treated with ethyl oxalate, 020^(02115)2, which does 
not act upon the trimethylamine, whilst the methylamine is 
converted into dimcthyloxamide, 0203(^11.0113)2, and the 
dimethylamine into the ethyl ether of methyl oxamic acid. 
This latter can be separated by cold water from the difficultly 
soluble diethyl oxamide ; on distillation with caustic potash 
it is converted into potassium oxalate, alcohol, and dimethyl- 
amine : 

CA { N^l\+^ KOH=CA { g| + HO.C,H. + N { g^*)^ 

The alcoholic solution is neutralized with hydrochloric acid, 
evaporated down, and the residue, on distillation with potash, 
yields dimethylamine. 

This base is also formed on distillation of the so-called 
sulphite of aldehyde-ammonia with lime. This product, how- 
ever, was at one time supposed by Hofniann to be its isomeride, 
ethylamine.^ 

Dimethylamine also occurs in Peruvian guano 2 as well as in 
the products of distillation of wood (Oamille Vincent). It 
is an ammoniacal -smelling, readily inflammable liquid boiling 
at between 8° and O"*. 

Hydrochloinde of Dimethylamine or iJimrfhyl-ammonivm CMo- 
ride, N(OH3)2H201, is a white deliquescent mass crystallizing 
in scales, and forming with gold chloride, and platinum chloride, 
crystallizable compounds. 

Trimethylamine, N(0H3)3. 

149 This occurs somewhat widely distributed in nature. Thus, 
for instance, it is found in various plants, as the Chenopodium 
mdvaria. Arnica montana, Mercurialis annua, the bloom of the 
hawthorn, that of the wild cherry, and of the pear, as well as 
in ergot, and other fungi parasitic ou cereals. It also occurs 
in various animal liquids, and especially in herring- brine. It 
is likewise found as a product of decomposition of various 

* rjossmaiiii and Petersen, Ann, Chem. Pharm, cii. 317. 
- Lucius, IbUL ciii. 105. 



222 METUYL COMPOUNDa 



alkaloids, and amongst the products of the dry distillation of 
nitrogenous organic matter and of wood. 

Before Hofmann's investigation on the amines it was believed 
that the base occurring in nature was the isomeride, propylamine. 
He prepared it first according to the method described, and 
afterwards he and Winkles ^ obtained it in larger quantity by 
distilling herring-brine, in which Wertheim * had first found it, 
together with lime.. 

It has lately been prepared in large quanties by Vincent in 
the distillation of the **vinasses" of the French beet-root 
sugar refineries. A solution of the sulphates of ammonia and 
trimethylaminc is thus obtained from which the first salt can 
be partially separated by crystallization. The darkly-coloured 
mother-liquor is then distilled with lime, and the product passed 
into hydrochloric acid. This solution is then boiled down until the 
temperature reaches 140°. The sal-ammoniac present crystallizes 
out on cooling, and the mother-liquor is drawn off from this, and 
further evaporated until the boiling-point rises to 200° ; the 
residue thus obtained consists of commercial hydrochloride 
of trimethylaminc, from which the free base can be readily 
prepared by treatment with an alkali. 

Trimethylaminc is a mobile liquid boiling at from 9° to 10** 
and having a specific gravity of 0*673 at 0° (Rlennard). It 
has a powerful and penetrating characteristic fish-like smell. 
It is very soluble in water and the concentrated aqueous solu- 
tion, as well as the pure base, is easily combustible. Devillier 
and Buisine^ found from 5 to 10 per cent, of this base in the 
commercial trimethylaminc, together with 50 per cent, of 
dimethylamine, whilst the remaining, and about equal part, 
consisted of ethylamine, propylamine and iso-butylamine. 
According to Vincent* this depends upon the fact that the 
*' vinasses " of different preparations do not always yield the 
same products, and that their relative amount depends upon the 
circumstances under which the distillation is conducted. 

Trimethylaminc is now used for the purpose of preparing 
pure potassium carbonate from potassium chloride, the process 
adopted being exactly similar to that described in Vcl. II. 
Fkrt I. p. 152 as the ammonia-soda process. The reason that 
anunonia cannot be employed in the preparation of potassium 
carbonate is that sal-ammoniac and hydrogen potassium 

» Chem. ftoc, Joum, v. 28<». ' Wicn, Akad, Brr. vL 113. 

> Ompt, Bend, lixxix 4m. * Ibid, Ixxxix. 238. 



TETRAMETHYLAMMONIUM COMFOUNDS. 22:^ 

carbonate are about equally soluble in water, whilst the hydro- 
chloride of trimethvlaniine is a much more soluble salt. In 
addition to this, it has been employed in medicine, and is said 
to have been of value in cases of acute rheumatism and gout. 

Hydrochloride of Triraethylavihie or Trimethylammonium 
Hydrochloride, N(CH3)j,HCl, forms deliquescent crystals, and 
serves, as has been mentioned, for the preparation of methyl 
chloride. It unites with platinum chloride to form the com- 
pound 2N(CH3)3HC1 + PtCl^, crystallizing in orange-coloured 
octohedrons. The sulphate forms, with aluminium sulphate, 
the alum [N(CH3)3H]2SO, + Al2(SO,)3 + 24H2O, crystallizing 
in transparent octohedix>ns, possessing an astringent taste, and 
smelling of herring-brine. Trimethylamine combines with 
carbon disulphide, yielding, with considerable evolution of 
heat, the compound CS2,N(CH3)3, which crystallizes in rhom- 
bic needles from alcoholic solution, and is decomposed by both 
alkalis and strong acids into its constituents. Dilute acids, on 
the other hand, unite with it to form salts. When it is brought 
in contact \^ith an equal number of molecules of hydrochloric 
acid, the neutral compound, CS2,N(CHg)3,HCl, is formed, 
which, when in contact with more acid, yields the compound 
2CS2,N(CH3)3, 3HC1. 

Nitric acid and sulphuric acid form corresponding compounds.* 

TETRAMETnYLAMMONIirM COMPOUNDS. 

150 The iodide, N(CH3)4l, as har, been mentioned, is the 
chief product of the action of ammonia on methyl iodide, and 
is readily formed by the union of the latter compound with tri- 
methylamine. It crystallizes from hot water in shining white 
needles, which possess an intensely bitter taste. On heating, it 
decomposes into trimethylamine and methyl chloride, which, 
however, reunite on cooling. The iodide possesses the property 
of yielding, with chlorine and iodine, several crystalline poly- 
chlorides and polyiodidcs, which easily undergo decomposition. 
When freshly precipitated silver oxide is added to a solution of 
the iodide, the hydroxide, !N(CH3)40H, is formed. This yields 
on evaporation in a vacuum, a crystalline mass, which rapidly 
absorbs water and carbon dioxide from the air. It acts as a 
powerful caustic, is strongly alkaline, and generally resembles 
the fixed caustic alkalis in its behaviour. On neutralization 

^ Blennard, Compt. IteruL Ixxxvii. 1040. 



226 METHYL COMPOLXLa 



ether of cyanic acid. It is obtained by distilling a mixture of 
freshly - prepared potassium cyanide with potassium methyl 
sulphate, and it is a mobile liquid which has an excessively 
suffocating odour, its vapour vigorously attacking the mucous 
membranes. Aqueous acids and alkalis decomposes it with 
formation of carbon dioxide and methylamine : 

When dry, ammonia acts upon methyl carbimide, methyl urea 
18 formed, and this is likewise produced when the vapour of 
cyanic acid is passed over methylamine, or when a solution of 
potassium cyanate is evaporated with sulphate of methylamine. 
The formation from the carbimide occurs as follows : 

M(»tliyl urea forms long transparent prisms easily soluble in 
wiitor, and combining with acids to form cry stall izable salts 
(Wilrt/J. 

WIhmi nirthyl carbimide is brought in contact with water, 
Jimffliyl'Hirn in formed : 

•j(-().N(Cir3) + H,o : 0.1) 1 5i[!'|y[[ + m^ 

Tlin HtiUM^ compound is proilucfd by acting on cyanic acid 
Willi innthj'Iiunine. Dimethyl-uroa forniH crystals which melt 
III. jOO", find it boils without decomiMisition at 270". It is 
MMttily Mnlubh? in water, and combines with iwids (Wlirtz). 

Ti'tmeihi/l Ttncarhimide, CjOjCXCH,),, is a polymeric modi- 
rti'iilinii of carbimide formed in the preparation of the latter 
i<otii|»oMtid, and also produced when this sulstanco is allowed 
|o mImihI. It iM likewise obtained, as above described, from 
I III* ryiuiunito, iiM well as when potassium cyanurat^j is distilled 
with iHitim>«iinn mothyl sulphate. It crystallizes in sliort prisms, 
wliicli do not diMm>Ive in cold water, are slightly soluble in hot 
WMtiT, anil cnwily wihiblo in alcohol. They melt at 175" and 
boil III 271". 

Alft/n/f Thinn/tnwtf, NO.SCH^.was first obtained byCahours' 
on difitilling a <*onc(*ntratiHl solution of equal parts of potas- 
ntuni thi(N'yanat(« and cah'ium methyl sulphate. It is a colour- 

> Ann. iltim. /7ij/j». p). xviii. 281. 



XITRO-COMPOUNDS OF METHYL. £27 



less alliaceous-smelling liquid. At O'' its specific gravity is 
1-088, and it boils at 133". 

Methyl Thiocarbimide or Methyl Mustard Oil, CS.NCH,. When 
methylamine is brought in contact with carbon disulphide, 
metbyl-thiocarbamic acid, CS(NH.CH3)SH, is produced, the 
silver salt of which, when heated with water, decomposes as 
follows : 

CS ( si^^^'^ - 2N { ^^3 + Ag,S + H,S. 

Methyl thiocarbimide is a white crystalline solid, which melts 
at 34'' and boils at ll9^and smelh strongly of horse-radish. 
It combines with ammonia to form crystalline methyl thio- 
carbamide, CS(NCH3.H)NH2. The crystalline hydriodide is 
isomeric with methyl thiocarbamide iodide, CS(NH2)2CH3T, 
obtained by the union of carbamide with methyl iodide. It 
possesses the characters of a sulphino compound, yielding 
with silver oxide and water a strongly alkaline hydroxide, 
CS(NH2)2CH3.0H, which yields well crystallizable salts with 
adds.* 



NITRO-COMPOUNDS OF METHYL. 

152 KitrO' Methane, CH^NOg, is formed when concentrated 
solutions of potassium nitrate and potassium chloracetate arc 
boiled together : 

CH.Cl.CO.K + KNO2 + H2O zr CH3NO2 + KCl + HKCO;,. 

The compound thus formed was termed by Kolbo - nitro-car- 
binol. About the same time V. Meyer and Stiibcr ^ obtained 
the same compound by acting on methyl iodide with silver 
nitrite, when a violent action occurs. 

Nitro-methane is a heavy liquid, possessing a peculiar smell, 
and boiling at 101°. It acts as a weak acid, solidifying with an 
alcoholic soda solution to a mass of fine needles, having the 
composition CHgNaNOg + CoHgO. These, when dried over 
sulphuric acid, fall to a light powder, which detonates on 
heating, and undergoes spontaneous decomposition when kept. 
Its concentrated aqueous solution is still more unstable, for 

' Bernthsen and Klingcr, Bcr. Dculsch. Chem. Ges. xi. 492. 

- Journ, frac. Chem. [2], v. 42 7. 

3 Drr, Deutsrh. Chcvi, Ocs, v. .'514 : Liehv/s Ann. clxxi 




228 METHYL COMPOUXD& 



after a few moments it suddenly suffers decomposition with 
evolution of heat. 

The freshly prepared solution gives characteristic precipitates 
with many metallic salts. Of these, the yellow mercury com- 
pound is the most singular, as it is extremely explosive, deto- 
nating strongly if merely touched, when in the dry state, with a 
glass rod. Two milligrams of the compound when heated on a 
platinum cover explode with a noise equal to that of the 
discharge of a pistol. 

On heating nitro-methane with fuming sulphuric acid, carbon 
dioxide and hydroxy lam ine are formed.^ 

CH3 NO2 = CO + NOH3. 

When nitro-methane is dissolved in caustic potash, and some 
potassium nitrate added and then dilute sulphuric acid, a deep 
red solution is obtained, the colour of which disappears on addi- 
tion of more sulphuric acid, and is reproduced on the addition 
of alkalis. This reaction depends on the formation of methyl 
nitrolic add, CH(N02)N0H, of which the alkaline salts have a 
deep red colour (see p. 171). The free acid forms large glisten- 
ing crystals, soluble in water, alcohol and ether. It is an ex- 
tremely unstable body decomposing on standing. When heated 
to 64** it melts with evolution of red fumes, whilst formic acid 
remains behind. This latter compound is also formed on boiling 
with dilute sulphuric acid, when nitrogen monoxide is evolved.* 

CHjNjOg = CH2O2 + NjO. 

If nitro-methane be heated with alcoholic solution of caustic 
soda, a crystalline mass of sodium methazonate is formed, which 
is permanent in the air and highly explosive. 

Mdhazonic acid, CjH^NjOj, obtained from this, can be ob- 
tained from solution in ether or benzol in large crystals, which, 
on heating, decompose with explosive violence^ and at the ordi- 
nary temperature undergo rapid change with formation of a red 
colour.* 

' Pn'ibisch, Joum, Prac Chem, [2], viii 816. 

• Meyer, Licbigs Ann, clxxv. 97 ; Tachernink, ibid, clxxx. 166. 

» Frkae, Btr, DciUsch. Chem. Get. ix. 894 ; Lecco, Hid. 705. 



METHYL PHOSPHINE. 220 



PHOSPHORUS COMPOUNDS OF METHYL. 

153 Paul Thenard ^ in 1846 examined the properties of several 
volatile compounds containing phosphorus which he hail ob- 
tained by acting on calcium phosphide with methyl chlorido. 
Amongst these occurred trimethylphosphine, P(CH3)^and tetra- 
methyldiphosphine, "2^(01^^. In 1855 Cahours and Hofmunn ' 
investigated the substances obtained by the action of methyl 
iodide on sodium phosphide, and discovered, in addition to the 
two bodies just mentioned, tetramethylpbosphonium iodide, 
P{CIl3)4T. They likewise found that by this process explosive 
bodies are produced, and, for this reason, the investigation is 
not without danger. On this account they sought for and suc- 
ceeded in finding a better method of prcjnration, which will 
afterwards be described. 

Monomethylphosphine and dimethylphosphine were discovered 
by Hofmann in 1871.* 

Methyl Phosphine, V{GK^Y{^, is formed by the action of 
phosphonium iodide on methyl iodide in the presence: of zinc 
oxide : 

2 CH3I + 2 PHJ + ZnO = 2 PCCigH^I + Znl,-f- H/). 

The secondary base is formed at the same time, according to 
the equation : 

2 CH3T -f- PI I J -f- ZnO = PCCiygH^I + Znl^ + H^O. 

In order to prepare these compounds, the materials are mixed 
in the proportions indicated by the fir:st equation, placed in 
carefully closed tubes, and then heated from six to eight hours 
to 100°. After this operation, the contents of the tubes fonn a 
crystalline mass* consisting of the two double zinc salts. The 
primary base is obtained from these by decomposition with 
water, whilst the diniethyljibospbine salt remains unaltered, but 
may be decomposed by alkalis.* 

In order to prepare the free bases, the product of the reaction 
is brought into the vessel A, Fig. 62, filled with hydrogen, and 
water is allowed to drop upon the mass. Methyl phosphine gas 

' Compt, Rend. xxv. 289. 

« Fhil. Trans, 1857, 575 ; see also Chein. Soc. Joiim. xiii. 289 ; xiv. 73, 316. 

• Proe. Eoy. Soc, xx. 221. 

* llofmano, Ber. Dcutsch. Chem. G(8. iv. 605. 



SltTBVL COMPOLSI^, 



u then evolved willi liUsio^ and effenescence ; tLU is allowed 
to pass tliFOugb a spiral tube surrouudcid by a freezing mixtore 
into tbe vessel H, aUo well cooled, in wLicb it is ooodensed. 
Wlieu lit t:v-;>!iitioD of ^as lakvs place oq farther addition of 
wau^r, tiie cri.'stalline mass is heated until the whole is dissolved, 
when a t-udfJen torrent of gas is frequently given off, and hence 
the receiver is connected with a condenstug flask, K, containing 
crjnceiitnited byilii'jdic acid, in wliich any uncoadeosed gas 
v.'liiclt riii^ht otherwise escape i:i absorbed. 




Methyl phosphinc itt a colourless gim, possessing an cxi'essivcly 
poweiful odour It condenses on cooling or under pressure to n 
liiliitd I»oiliii^' ut -14°, and its vapour density is 1GS7. On 
lixposurc to air, it evolves white fumes, and takes firo even when 
hut slightly warmeil. In contact with chlorisc, bromine, or 
nitric oirid, it burns with a bright flame. It f'lrins with acids 
a well-dufmed Hcrics of salts which, like those of pliosphurotted 
hy(Iro;ieu, are dcconipoitcd by water, and possess moreover the 



PHOSPHORUS COMPOUNDS OF METHYL. 131 



singular property of bleaching vegetable colours like chlorine, 
a reaction which is not exhibited by the free base. This may 
be well shown by bringing a piece of litmus-paper, half moist- 
ened with water and half with acid, into the gas, when the latter 
lialf only will be bleached. 

Methyl Phosphonium Chhride, P(CH3)H3C1, is formed by the 
union of its two anhydrous constituents. It crystallizes in four- 
sided tables, which are so volatile that their ethereal solution 
evaporates as a whole. 

Methyl Phosphonium Iodide, P(CH3)H3T, separates from con- 
centrated hydriodic acid in large compact crystals, and can 
easily be obtained pure by sublimation. 

Methyl PJiosphinic Acid, P(CH3)0(0H)jj, is obtained when the 
base is passed into concentrated nitric acid. It forms a hygro- 
scopic, spermaceti-like, crystalliue mass, which melts at 105°, is 
easily soluble in water, and posse&ses a purely acid taste. Being 
a dibasic acid, it yields two series of salts.* 

Phosphorus pentachlorido decomposes it into the chloride, 
P(CH3)OCl2, a white crystalline body which melts at 32° and 
boils at 163°, and is decomposed with explosive violence by 
water.* 

This compound is isomeric with metliylphosphorous acid, 
from which, however, it is sharply distinguished by its 
properties. 

154 Diniethylphosphine, P(CH3)2H. If caustic soda solution bo 
added to the liquid from which methyl phosphino has been ob- 
tained, the secondary base is liberated, and separates out in a 
layer on the top of the liquid. It is a colourless liquid, boiling 
at 25°, and taking fire instantly on exposure to the air, burning 
with a very luminous, phosphorus-like flame. If the atmo- 
sphere of hydrogen in which it is prepared contains even a trace 
of air, this is instantly observed by the formation of a white 
cloud, and dangerous explosions may ensue in the preparation of 
this body, unless great care le taken. It forms with acids ea:?ily 
soluble salts. The hydrochloride yields with platinic chloride a 
well crvstallizable double salt.^ 

Nitric acid oxidizes the base to dimethylphosphinic acid, 
P(CH3)20.0H, a white paraffin-like mass, melting at 7G°, and 
volatilizing without decomposition. It is a monobasic acid, and 
yields a well-defined series of salts.* Phosphorus pentachloride 

» Hofiimjiii, />Vr. Deutsch. Chcm. Grs. v. 104. ^ Ibid. vi. 303. 

» m-f. iv. (qo. -» Hid, V. 108. 



232 MKTHYL COMPOUNDS. 

couverts it iato tho chloride. P(CHj)jOCl, a cryatalline body 
melting at 66", aud boiling at 204>°, and being slowly decomposed 
by water.' 

155 Trimethyl PkospUne, P(CH,)j, is obtained by acting on 
pboaphorus trichloride with zinc methj'l : 

3 Zn{CH,)^ + 2PCI, = SZuCI, + 2 PCCHg),. 

The apparatus employed for preparing this substance 13 
shown in Fig. C3. A pipette furnished with a stopcock contains 
phosphorus trichloride, and the retort a mixture of ether and 
zinc methide. This is connected with a bent tube, in which a 
few drops of phosphorus trichloride are placed, whilst to this is 




attached a cylinder (c) containingdry carbon dioxide, the whole of 
the apparatus being filled with the s»nie gas before thu beginning 
of the experiment from the evolution flask (a). The tricldorido 
is then allowed to pa^s drop by drop into the retort, when 
a reaction takes place as violent as that observed when sul- 
phur trioxide acts on caustic baryta, so tluit the zinc methyl 
is partly volatilized, and cnrriod forward not only into the re- 
ceiver but into the bent tube, where it meets with the phosphorus 
trichloride, and is absorbed. The drop of trichloride scr\-es also 
as an indicator of the prt^nress of the reaction. After a time the 
action Ifccomes less violent, and when no further evolution of 
' H.-fiiiunn, B/^r. Ik-iilxh. rhnn. fir,, vi. 307. 



TKIMETHYL PHOSPHINE. 233 



beat takes place, it is complete. In the receiver and bent tube, 
and sometimes even in the cylinder (c), two layers of liquid are 
found, of which the upper one consists of a mixture of ether and 
phosphorus trichloride, which may again be employed in a 
second preparation of the base ; the second and heavy layer is a 
compound of trimethylphosphine with zinc chloride. For the 
purpose of obtaining the free base, solid caustic potash is added 
to this liquid, and water gradually allowed to drop in, when so 
much heat is evolved that the base distils over ; this then is dried 
over caustic potash and rectified. These operations must be 
carried on in an atmosphere of carbon dioxide. 

Trimethylphosphine is also easily formed by heating methyl 
alcohol with phosphonium iodide in sealed tubes. ^ 

3CH3.OH -f PH,I :=z P(CH3)3HI 4- 3H2O. 

If it is desireil to prepare it according to this process, two 
molecules of the iodide are added to only five molecules of 
alcohol in order to avoid the formation of tetramethyl phospho- 
nium iodide. In this case, however, large quantities of phos- 
phine are formed by a secondary reaction, and hence it is 
necessary to employ strong and well fused tubes, which must 
be beated for many hours to 180^ The product thus obtained 
yields the firee base on treatment with caustic soda solution. 

The formation of this compound by heating phosphonium- 
iodide with carbon disulphido to 150° is of great theoretical 
interest : * 

SCS^ + 4PH,I = P(CH3)3HI + ;3H,S -f 3PSI. 

Trimethylphosphine is a light, mobile, powerfully refracting 
liquid, which boils at from 40° to 42°, and has a most indescrib- 
able and penetrating odour. It fumes in the air, and on ex- 
posure becomes surrounded by a crystalline crust of trimethyl- 
phosphine oxide, P(CH3)30, and frequently takes fire. It also 
combines directly with sulphur, selenium, and the elements of 
the chlorine group, as well as with carbon bisulphide. The 
compounds thus obtained closely resemble the corresponding 
triethylphosphines. 

156 Tctramcth/lphosplionium Iodide , Pi'CHj)^!, is formed by the 
union of methyl iodide with trimethylpliosp'.iine, and, together 

* llofmann, Bcr. Dcittsch, Chem. Gcs, iv. 205, 372. 

* Drcchsel, Joxmu Proc. Chcm, ['!], x. 180. 



234 METHYL COMPOUNDS. 



with the tertiary base, by heating methyl alcohol with 
phosphonium iodide : ' 

4 CH3.0H + PH,I=P(CH3),I + 2H20. 

It crystallizes from hot alcohol in beautiful glistening white 
crystals, which assume a reddish colour on exposure to air. A 
strongly alkaline hydroxide is obtained by acting with moist 
silver oxide on its aqueous solution, and this decomposes on 
distillation into methane and trimethylphosphine oxide : 

P(CH3),01I =CH, + P(CH3)30. 

Tetraniethyl Dipliosphidc, P2(CH3)^. This compound, cor- 
responding to liquid phosphuretted hydrogen, was, as has been 
stated, discovered by Paul Thenard, and then observed by Cahours 
and Hofmann. It is a thick, colourless liquid, possessing a most 
unpleasant smell, boiling at 250°, and flaking fire on exposure 
to air. 



ARSENIC COMPOUNDS OF METHYL. 

157 In the year 17G0, the French chemist Cadet observed that 
a mixture of equal parts of acetate of potash and white arsenic, 
when heated, yields, together with white arsenic and acetic acid 
containing arsenic, a heavy brownish-red liquid which has a 
most frightful smell, and fumes strongly in the air.^ This fact 
was confirmed by Duraude,^ whilst Thdnard * investigated this 
compound, which was termed Cadet* s fumhuj arsenical liquid, 
and gave to it the name of *'acetiie oho-arsenical" It is, however, 
to the classical research of Bunsen,^ carried on for many years 
under circumstances of no slight danger, that we owe an exact 
knowledge of the arsenical methyl compounds. 

Bunsen showed that Cadet's liquid, as well as its numerous 
derivatives, contains a radical having the formula C^H^As, 
and that this substance, in its chemical relations, exhibits 
striking analogies with a metal. He succeeded in isolating this 
body, and as we have already seen, this discovery contributed 
largely to the development of the theory of compound radicals. 

* Hofmann, Brr, Deutsch, Chcm. Gts. iv. 20.'». 

• Mi in, lie Math, et Phys. Pres. ikn Savants £iranff. iii. 6U3. 

• Xvurfaii Chilli. Prnc. Thcor. iii. 89. 

* Jun, dc Chim. Hi. f)!. 

' Ann. f'hriii. Ph(tn>i. xxiv. 'J?! ; xxvii. 14S ; xxxi. 175 ; xxxvii. 1 ; xlii. 14 ; 
xlvi. 1 ; and Clum. Sjc. Man, 1M41, i. 4l» ; Phif, May. [:tj, xx. 180, 395 ; xxii. 180. 



ARSENIC COMPOUNDS OF METHYL. 235 



This body, like most of its compounds, possesses a frightfully 
offensive odour, so much so that the air of a room contain- 
ing even a trace of the vapour is rendered so unbearable as 
frequently to cause vomiting. For this reason the name 
cacodyl {KaKwSrj*:, stinking) was given to this compound by 
Berzelius. 

Various hypotheses have been put forward respecting the 
constitution of this radical. Kolbe * first suggested the view 
that it was arseU'dimethyl, As(CH.^)2. This was rendered very 
probable by the experiments of Frankland,^ and this view was 
afterwards corroborated by Cahours and Riche.^ The latter also 
<liscovered trimethylarsine and the tetravidhijlarsonium com- 
pounds. But it is to Baeyer,* who at a later period, in a 
masterly investigation, first prepared the arsai-jnoTwrnethyl com- 
pcninds, that we are indebted for the full explanation of the 
relations which these various bodies bear to one another. 

The arsenic compounds of methyl and of the other alcoholic 
radicals played an important part in the development of theo- 
retical views, not only because they furnished us with the first 
example of an isolable organic radical, but also because they 
served Frankland ^ and Kekule ^ as a means of more exactly 
illustrating the meaning of the term ''chemical valency." 

The arsenic compounds of methyl may be considered as being 
derived from arsenic trichloride by the partial or complete 
replacement of the chlorine by the alcohol radical : 

Arsenic trichloride. Arsen-methvi dichloriile. 

( Cl ( CH3 

As-|Cl As-^Cl 

( 01. ( Cl. 

Arseii- dimethyl cliloride. Triniethylai-siiie. 

As^CH, -JCH3 

Cl. V CH.w 



The chlorine of these compounds may be replaced by other 
elements or radicals, and for this reason arsen-monomethyl is 

1 IlaiidworUrh. iii. 442 ; iv. 222. • Joum, Chem, Soc. ii. 297. 

* Compt. Jitmi, xxxvi. 1001 ; xxxix. 541 ; Ann. Chem. Pharm. Ixxxvili. 316, 
xc-ii. 3G1. 

* Ann, Chem, Phann. cvii. 257. 

' Phil. Trans. 1852, p. 440; or L'jcjKrimaiht I Pc'scarchc^^lSS, 
'' Ann. Chan. Pharm. cvi 120. 




236 MKTHYL COMPOUNDS. 



considered as a dyad, and arsen-di methyl as a monad radical. 
These arsenic compounds are, as Baeyer has shown, mutually 
convertible. They combine like phosphorus trichloride, with 
one molecule of chlorine, and the bodies thus obtained easily 
decompose with evolution of methyl chloride. The compound 
of arsen-mouomethyl is, however, so unstable that it can only 
be preserved in a freezing mixture : 

As(CH3)3Cl2 --= CH3CI + As(CH3)2Cl. 
As(CH3)2Cl3 = CH3CI + AsCChJcIj. 
As(CH3) CI, -^ CH3CI + ASCI3. 

THmethylarsine, As(CH3)3, is obtained, together with cacodyl 
and tetramethylarsonium iodide, by the action of sodium 
arsenide on methyl iodide (Cahours and Riche). It is produced 
on treating arsenic trichloride with zinc methyl : ^ 

2ASCI3 + SZnCCHy), = 2As:CH3)3 + SZnClj. 

In place of arsenic trichloride, cacod}l iodide may be 
employed. It is, however, best prepared by distilling potash 
with tetramethylarsonium iodide or one of its double salts,^ 
which will be described hereafter. It is a strongly refracting 
liquid, boiling at about 70"*, and possessing a highly penetrating 
and disagreeable odour. It does not form salts with acids, but 
on exposure to air becomes heated, without taking fire, owing 
to its absorption of oxygen to form a crystalline oxide. It also 
unites directly with sulphur and the elements of the chlorine 
group, yielding crystalline compounds. 

Tetramethylarsonium Compounds, The iodide, As(CHj),I, is 
the chief product, of the action of methyl iodide on sodium 
arsenide, and remains behind as a white crystalline mass when 
the trimethylarsine and cacodyl, which are formed at the same 
time, are removed by distillation in an atmosphere of carbon 
dioxide. It is also forrped by the action of methyl iodide on 
cadodyl : 

(CHj^As., + 2CH3I = (CH3),AsI -f (CH3)2AsI. 

When treated with silver oxide, the aqueous solution yields 
the corresponding hydroxide, As(CH3),0H. This substance 
has a strongly alkaline reaction, and, on evaporation, is de- 
posited in the form of deliquescent tabular crystals. When 

* Cahoan and Kiche, Compfrji Jlenfius, xxxix. 5*1. 
'"' Cahouris ComfittM llendtu^ I. 1022. 



THE CACODYL COMPOUNDS. 237 



arsenic is heated with methyl iodide to 200°, the compound 
As(CH3)^I + Aslg is obtained, crystallizing from hot alcohol in 
red glittering needles. On heating arsenide of zinc with methyl 
iodide to 180**, the double salt AsCCHj)^! + Znig is obtained, 
and this separates from hot alcohol in white needles. A 
corresponding cadmium compound is also known. 

When zinc methyl acts upon tetramethylarsonium iodide, and 
the product thus obtained is distilled, a considerable quantity of 
trimethylarsine passes over first, and then a liquid which, 
according to Cahours,^ is pentamethylarsine, As(CH3)5. It is de- 
composed by iodine into methyl iodide and tetramethylarsonium 
iodide whilst hydrochloric acid yields the corresponding chloride, 
together with marsh gas. This singular body deserves further 
examination. 



The Cacodyl or Dimethylarsine Compounds. 

158 The point of departure of these bodies is Cadet's liquid, 
or alcarsin, as Bunsen termed it, giving it this name because he 
at first believed it might be considered as a polymeric alcohol, 
oxygen being replaced by arsenic. 

According to Baeyer, the best mode of preparing this sub- 
stance is to heat equal parts of white arsenic and anhydrous 
sodium acetate in a retort in quantities of about 3 kg. at a 
time, allowing the vapours to pass through a Liebig's condenser 
into a receiver containing water. Highly poisonous gases are 
thus given off, which must be allowed to pass up a flue into 
the open air. The heavy oily liquid consists chiefly of cacodyl 
oxide, which is formed according to the following equation : 

4CH5.CO2K + AS2O3 r_- [(CH3)2As]20 + 2K/JO3 + 2C0,. 

In addition to this, some free cacodyl is formed by reduction, 
and this it is which gives to the crude product the property of 
spontaneous ignition. Acetic acid, acetone, marsh gas, ethylene, 
water, and arsenic occur as by-products. For the purpose of 
purification, the crude oil is distilled with several times its 
weight of hydrochloric acid and corrosive sublimate. In this 
way pure cacodyl chloride can be obtained, w^hich may be 
converted into the pure oxide by distillation with caustic 
potash. 

^ Ann. Chtm. Pharm. cxxii. 338, 



i 



238 METHYL COMPOUNDa 



Cacodyl Oxide or Dimethylarsine Oxide, /pTj^\*A f ^- '^^*^ 

is a colourless, heavy liquid, which is not soluble in water, but 
dissolves in alcohol and ether. It boils at about 150^, and solidifies 
a few degrees below —23°, forming a crystalline mass ; it does 
not fume in the air, but its vapour, when mixed with air, explodes 
if heated above 50°, It possesses a frightfully irritating smell, 
destroying the mucous membrane and producing insensibility, 
and acts as a very powerful poison. Although it does not 
possess an alkaline reaction, it is a very strong base readily 
uniting with acids to form salts. 

Cacodyl Chloride,- (CH3)2AsCl. When the oxide is heated 
with hydrochloric acid alone, not only is the chloride formed 
but also the oxychloride in considerable quantity; the pro- 
duction of this latter being avoided by the employment of 
corrosive sublimate. Cacodyl chloride is a heavy, colourless, 
transparent liquid which boils at a temperature not far from 
100^ yielding a vapour whose density is 4 56. The vapour 
ignites spontaneously on exposure to air, burning with a 
pale arsenic-like flame. Heated in oxygen it explodes most 
violently. It does not fume on exposure to air but absorbs 
oxygen, forming crystals the composition of which has not been 
ascertained. Its smell is very penetrating and stupefying, far 
surpassing in this respect the smell of the oxide. Inhaled in 
even moderate quantity it produces such inflammation of the 
mucous membrane of the nose that the vessels swell up, and 
the eyes are congested with blood. Cacodyl chloride forms double 
salts with various metallic chlorides such as sal-ammoniac. The 
platinum compound, 2 (CH3)2AsCl + PtCl^, is obtained as a 
red precipitate by mixing alcoholic solutions of the chloride and 
platinum chloride. When this is dissolved in hot water yellow 
needles of cacoplatylchloride, (CH3)4A520.PtCl2 -f HgO, and 
from this other cacoplatyl compounds can be obtained. 

Cacodyl Trichloride, (6113)2 ASCI3. Cacodyl monochloride takes 
fire in chlorine gas. If, however, it be dissolved in carbon 
disulphide and chlorine led on to the surface of the liquid the 
trichloride crystallizes out in transparent prisms which decompose 
at 40° into methyl chloride and methyl-arsen-dichloride. 

The compounds of cacodyl with, the other members of the 
chlorine group chxdjr rciiio bte the chl<mdea. ^ 

Cacodyl CJy04l4b^G|U|^ffll)|)» ii fonned by distilling the 
oxide milytfiHiJ^^^^HliHrflL^^ m well as by acting 



THE CACODYL COMFOUKDS. 239 



on llie same substance with mercuric chloride. It crystallizes in 
large glistening four-sided prisms which can be sublimed. They 
melt at 33^ and boil at about 140^ This compound is scarcely 
soluble in water though easily so in alcohol and ether. When 
heated in the air it takes fire and bums with a reddish-blue 
flame. This substance is extraordinarily poisonous, and for this 
reason its preparation and purification can only be carried on in 
the open air ; indeed even under these circumstances it is neces- 
sary for the operator to breathe through a long glass tube 
open at both ends, and thus to ensure the inspiration of air 
free from impregnation with every trace of the vapour of this very 
volatile compound. If only a few grains of this substance be 
allowed to evaporate in a room at the ordinary temperature, the 
effect upon any one inspiring the air is that of sudden giddiness 
and insensibility amounting to complete unconsciousness. These 
symptoms, however, last only for a short time, and are without 
subsequent evil effects, provided the operator withdraws himself 
in good time from the action of the poison (Bunsen). 

Cacoilyl Sulphide, /pxr*!^ a c S, was obtained by Bunsen by 

distilling the chloride with a solution of barium liydrosulphide. 
It is a colourless liquid which does not fume in the air, and 
possesses a highly disagreeable and unpleasant smell, reminding 
one at the same time of mercaptan and alcarsin, and one which 
remains attached to articles with which it has been in contact 
for a great length of time. It boils far above 100®, but volati' 
lizes together with aqueous vapour, and is very easily inflam- 
mable. It is decomposed by acids with evolution of sulphuretted 
hydrogen, and it yields, with solutions of various metallic salts, 
precipitates like those produced by sulphide of ammrnium. It 
combines with sulphur to form the disulphide (CH3)^As2S2, 
crystallizing from alcohol in large clear rhombic tables 
possessing an unpleasant smell, and fusing at 50°. 

Cacodyl Selenide, Ivilt x^ I Se, is obtained by distilling the 

(l^Jrlg^gAS ) 

chloride with sodium selcnide. It is a yellow liquid which in 
smell resembles the sulphide, but, at the same time, has an 
aromatic odour. It behaves towards solutions of the metallic 
salts like the selenides of the alkali metals. 

159 Dicacodijl, (CH3)^As2. This is the free radical of the 
dimethylarsine compounds. It is easily formed by heating the 
chloride with zinc from 90** to 100°: 






- z 



'I ■' '"i* ■■ II"*- T ■• -r 

.■\ w i : ".. : . i's 1 . V ■■• [ 

• f iiriii'is|)l:.:-ri :'.- -.- 
•' : «.'* . Tliv \>:.i> 

■■ ■« :; tii..xi(.le. Tlit- 
v-jMunp into tlio 



J' 



^ 







1 ■ « 






1 • ■ ■ ^ 



- • • ■ I - ; 






■ * ■ 



« I 1 f 1- 



CACOmXlC AOD. 341 



Dicacodyl is a heaTT, clear, moMe, Miu n ^ f niaamiz iitpbi 
which smells like the oxide, and undexgoes tnch a xkieBt oxiiia- 
tiou on exposure to air that when it is attenqned to drop ihe 
liquid firom a bottle the liquid takes firebefoteitleaTesthegiiw 
When air is allowed to con:e into contact with it alow It, it iocms 
a thick white cloud, and is conrerted into caoodjl oxide ai>l 
cacodylic acid. It boils at 170' and aolidines at —0^. f-rnusz 
large quadratic prisms. The Tapour density of caoodTi chkriie 
is 7'101. It bums in oxygen with a pale bhie flame, an>i 
when thrown into chlorine bums with a bright light with 
deposition of carbon. Shaken up with chlorine water it f.>nns 
cacodyl chloride. It also combines directly with sulphur and 
other elements yielding the compounds which hare been alneady 
described, and for this reason Bunseo correctlv obser\'es that this 
radical in every respect plays the part of a simple electro- 
positive element, and that it is indeed a true oryfinie fUment. 

With the haloid salts of the organic radicab it forms the 
arsenium compounds : 

(CH3J,Asj -f 2CJl5a = (CH^u(aH5)5AsC-l -h (CH3;:jAsCL 

CncoHylic Acid or Dinuthylarsenic Acil, AsOiCH^uOH, is 
formed by the further oxidation of the oxide in the air. It may 
be obtained more rapidly by pouring water on the last-named 
compound mixed with mercuric oxide : 

(CH3),A.%0 + 2 H-0 -f H^O = 2 (CH3),AsO.OH + 2 Hg. 

It is easily soluble in water, has an acid reaction, is odourless, 
and crystallizes from alcoholic solution in deliquescent oblique 
rhombic prisms. It is not attacked by fuming nitric acid or 
even by aqua regia, and according to Bunsen it is not poisonous, 
although the experiments of Lebahn and Schultz ^ have not alto- 
gether corroborated this statement, as they found that doses of 
four decigrams act fatally upon a rabbit. Phosphorus penta- 
chloride decomposes cacodylic acid into arsendimethyl trichloride : 

(CH.). AsO.OH + 2 PCI5 := (CH3)2AsCl3 -f 2 POCI3 + HCl. 

Concentmted hydrochloric acid converts cacodylic acid into the 
compound (0H3)As(OH)2Cl, to which Bunsen has given the 
name of cacodyl perchloride, as it is also obtained by the action 

^ Dcr, DjiitKk. Chtm, Ges, xii. 22. 
VOL. III. U 



2« 



THE llETHVL liROi 



of moist air oa the trichlorido. Water 
niiitioa of cacodvlic aci J. The salts of c: 
in vater ami crvstallize wiili difBcu 
(CHjijOAs-OAg, separates out from lio 
groups of needles. 



MOSOMETHVL ArSISE Co 

i6o Cacothl trichloriJe decoiikposes, as 

when heated to 4l>'-50° ioto inetiiyl el 

liieUaridf, As,CH,iOL wUicli compound 

heating cacoilylic acid in a current of h; 

A5,CH,.U>.0H + 3 HCl = AsfOH^jC 

It is a heavy, mobile, strongly rt'fractii 
Itd.>cs not fume in the nir and is not d 
which ii dissolves with tolerahle readine; 
Kxly attack the mucous membrane ii 
manner. If even smelt, the eyes, tlie i 
strell n'insidenibly. and a peculiar pierc 
the tbioat iBaeyen. The crvstalline te< 
is formeii when this boily is treated wit 
ivniivund is stable outy at a low ten 
dtivmji,>ses into methyl chloride and ara 
div-h!\*ride be saturatinl mulor water wi 
;;.:,W fAd,.. ../^ As CHjiO, is formed v 
eviilvi>vl, Slethylarsenoxide is soluble i 
and varbiui disulphide, and may be ol 
s.>lvent in lar^^ crvstals, apparently cuhi 
the repilar system. These melt at 95' 
itsafu'-tida. In a short time they uud< 
jK'iwUin-Iike mass, and in this respect 
jkrsv'nio trk>xidi- ; indeed in its general pi 
ai^penrs to hold a middle place betwe< 
ca^wtyl oxide. It fcnnswith hydriodic ac 
As,OHj'I,. crystallizing in long gHtteri 
s«-ssin): im smell, which melt at 25°, 
without d<.xt>niji<^siti.>n altove 200°. 

.Vit.\i\,-^us»lfJiu{.; M{CH^)S. is fo 
siOplmn-tt»>l hydi\>-;:eu on the chloride, f 
■.\vUol iToarlvn disulpliide in glittering 
»•' -h U.we a faint smell of us-tfcetida 



246 THE METHYL GROUP. 



ZinC'Methyl or Zinc Methide, Zn(CH3)2. This important body 
was discovered, together with its homologue, zinc-ethyl, in 1849, 
by Frankland.^ By this discovery our science was enriched 
with a new class of bodies, not only of the highest impoi-tance 
for the development of our theoretical knowledge, but also 
serving as the means of preparing a number of highly interesting 
carbon compounds, such as those of the alcohol radicals, with 
boron, phosphorus, and silicon, the tertiary alcohols, and many 
other bodies, some of which have already been described, and 
many others which will be mentioned in the sequel. 

Frankland obtained these zinc compounds by heating the 
corresponding iodides with zinc to a temperature of 150^ and 
subjecting the crystalline product of the reaction to dry dis- 
tillation. In the case of methyl iodide the compound obtained 
is Zn(CH3)I, and this when heated decomposes as follows : 

He also found that this reaction easily takes place at 100* in 
the presence of anhydrous ether, but then the ether cannot 
readily be separated from the zinc-methyl. If, however, the 
compound thus obtained be repeatedly heated with zinc and 
methyl iodide, nearly pure zinc-methyl can be obtained.^ 

Butlerow, who has employed large quantities of zinc-methyl 
in his researches, found it advisable to employ granulated zinc 
which had previously been treated with acid. This was then 
quickly dried and placed with the iodide in sealed tubes, which 
were afterwards heated to 100** until the whole of the liquid 
had disappeared.' 

Another method for the preparation of zinc-methyl in 
quantity consists in heating mercury-methyl, (CH3)2Hg, which 
can be readily prepared, with a large excess of zinc for twenty- 
four hours to 120V 

It is, however, most readily obtained according to the process 
described by Gladstone and Tribe.* These obser\*ers found that 
when copper is present under certain conditions, the reaction 
takes place very readily. For this purpose they make use of a 

' Journ. Chem. So^. ii. 297. 

* Wanklrn, Joum. Chem Soc. xiii. 124. 
» ZcitKh,/. Chem. 1863, 497. 

* Fmnkland and Duppa, Joum, fhnn. SW. xvii. 29. 

* Joum. Cfifm. /^or. 1879. i. 107. 



ZINC-METHYL. 247 



"copper-zinc couple/* prepared in the following way: Thin 
zinc foil, of which about 9 square dm. weigh about 2 grams, is cut 
into small pieces. These are then brought into the flask which 
serves for the preparation of the zinc-methyl. Eighty-four cbc. 
of a solution of sulphate of copper containing 2 per cent, of the 
anhydrous salt is then poured in, and in this way a spongy coating 
of copper is deposited upon the zinc. The zinc sulphate formed 
is then poured off, the metal washed with water, alcohol, and after- 
wards with ether, and dried in a current of coal gas or hydrogen. 
To this, methyl chloride is then added, and the crystalline zinc 
methyl iodide is formed slowly at the ordinary temperature, but 
quickly when warmed. This is then distilled in an atmosphere 
of carbon dioxide, and thus pure .zinc-methyl obtained. The 
same chemists have lately given a simpler method for preparing 
the " copper-zinc couple." Copper oxide is reduced in a current 
of hydrogen at as low a temperature as possible. One part of 
the metal thus obtained is brought into a flask with 9 parts of 
coarsely divided zinc filings, and the mixture, constantly shaken 
and turned round, is warmed over a gas-flame until the zinc 
filings begin to alter their form and become yellow. Then the 
powder is once more strongly shaken, and if the experiment 
succeeds the product must be a dark powder having a metallic 
lustre.^ 

In order to prepare zinc-methyl the apparatus shown in 
Fig. 66 is best employed. The flask (a) in which the mixture 
is contained is always connected to a reversed condenser, the 
upper end of which is placed in connection with a small bulb 
apparatus containing mercury, in order to prevent the access of 
air. Before the vessel is heated, the whole apparatus is filled 
^vith carbon dioxide. The end of the reaction is easily ascer- 
tained by no more methyl iodide running tack. The flask is 
then connected with the upper end of the condenser and the 
zinc-methyl distilled off and collected in a receiver filled with 
carbon dioxide and shut off from the air by means of mercury. 

165 Properties. — Zinc-methyl is a colovirless, mobile, strongly 
refracting li([uid, boiling at 46° and having a specific gravity 
at 10°-5 of 1-386. Its vapour density is 3*29 (Wanklyn). It has 
^ strong disagreeable odour, and instantly takes fire when 
bi:ought in contact with the air, burning with a bright greenish- 
blue flame with formation of thick clouds of zinc oxide. It bums 

^ Journ. Chan. Soc, 1879, i. r»»57. 



248 THE METHYL GKOUP. 

explosively in oxygen, and is decomposed with great violeiMs 
by water with evolution of marsh gas : 

Zn(CHj), + 2 H,0 := 2 CH, + ZnfOH),. 

Henco it 18 necessary in the preparation to avoid the presence 
of all moisture. 

According to Frankland, the accidental inhalation of its vapour 
produces symptoms of poisoning indicated by its powerful action 




Fiu. «<. 

on the nervous system. Friedel and Crafts ' also considered it 
highly poisonous. On the other hand, Wanklyn and Butlerow * 
state that it is not poisonous. The latter chemist ^vho, as has 
been said, lias worked for a long time with tliis material, men- 
tions thnt although it possesses an unpleasant smell, and for 
some time exerts a disagreeable sensation in the throat, and 
gives rise to dlHicuIty of breathing and violent coughing when 
inhaletl, these symptoms disappear after a few hours without any 
■ B^l. .Sot. Ciiiu. 1S45. ii 3.'.'. > ..^nti. CA^m. P/iann. •iliv. 8». 



ZINC-METHYL. 249 



visible effects remaining. By the action of methyl iodide or of 
zinc-methyl iodide at a high temperature, ethane is formed : 

(1) Zn J ^^8 + 2 CH3T = 2 C^H, + Ziil^. 

(2) Zn I ^^"3 ^ CH3 =. C,H, -f ZnT,. 

It is therefore necessary in the preparation of zinc-methyl 
that an excess of metal should be present, but in spite of this 
almost always some quantity of ethane, as well as of marsh gas, 
is formed, inasmuch as it is impossible to obtain either the 
apparatus or the material absolutely dry. 

When dry air is slowly brought in contact with zinc-methyl a 
crystalline mass smelling like camphor is obtained, having tho 
composition Zn(CCH3)CH3. This is decomposed by water into 
methyl alcohol, marsh gas, and zinc hydroxide. The same com- 
pound is also formed when zinc-methyl is acted upon by a small 
quantity of methyl alcohol, whilst when an excess is employed 
a second solid compound, Zn{OCH3)2, is formed (Butlerow). 

Iodine converts zinc-methyl first into zinc-methyl iodide, 
CHjZnl, a body already mentioned, and this on further treat- 
ment with iodine yields methyl iodide and zinc iodide. It has 
already been stated that the formation of zinc-methyl is assisted 
by the presence of ether, but that it is not possible to separate 
these two bodies by fractional distillation. This is not in con- 
sequence of the two substances boiling at nearly the same 
temperature, but because a distinct compound of the two is 
formed, having the composition 2 Zn(CH3)2 + (C.fl^)fi. Frank- 
land has proved this by emj loying, instead of common ether, 
methyl ether, which boils at 21°, and he thus obtained the homo- 
logous compound 2 Zn(CH3)2 + (CH3>20, which boils at the 
same temperature as zinc-methyl itself. Zinc-methyl readily 
absorbs sulphur dioxide with formation of methyl-zinc-sulpho- 
nate, (CH3.S02)2Zn, a compound examined by Hobson,^ who 
described it first as zinc-methyl- dithionate. He aloo prepared 
a series of other salts by double decomposition. Zinc-methyl 
combines slowly with nitric oxide, giving rise to a colourless 
crystalline body having the composition Zn(CH3)2(N02)2. which 
oxidizes so quickly on exposure to air that it readily takes fire. 
It is at once decomposed by water with formation of marsh gas, 

^ Joiirn. Chrvi. Soc. x 243. 



250 THE METHYL GROUP. 



zinc hydroxide, and ziiic dinitromethylate, Zn{CB[3)2(Nj02)2 + 
HgO, which yields, with sodium carbonate, the corresponding 
sodium salt Na(CH3)N202 + HgO. This separates from its alco- 
holic solution in crystals which on heating deflagrate powerfully. 
The constitution of these singular bodies is not known. The 
following formulae and equation may, however, probably express 
their composition : 

Zn(CH3)2 + 2 NO HZ CH3.Zn.O.N:N.O.CH5. 
2 CH3.Zn.0.N : N.O.CH3 + 2 H^O z= Zn^Q JJ ; ^ q c& 

+ 2 CH, + Zn(0H)2. 

When sodium is allowed to act on an ethereal solution of 
zinc-methyl, sodium methyl, NaCH3, is formed. This body 
has probably not yet been obtained in the pure state. Its 
existence is, however, proved by the products obtained by the 
action of carbon dioxide on this substance, when heat is 
evolved and sodium acetate is produced : ^ 

NaCHg + CO, ^ NaCO^CHj. 

x66 Mercury-Mcthyl, Hg(CH3)2, was discovered by Frankland, 
who obtained it by the action of light on methyl iodide in 
presence of mercury, when the crystalline compound, mercury 
methyl iodide, Hg(CH3)I, is formed, and this, when heated 
with zinc-methyl, is converted into mercury-methyl. The same 
compound is obtained by the action of zinc-methyl on mercuric 
chloride, and Frankland and Duppa ^ discovered another very 
simple method by which this body can be obtained in any 
desired quantity. Sodium amalgam does not act upon methyl- 
iodide in the cold, but if methyl acetate be added, heat is 
evolved and mercury-methyl is formed : 

2CH3I + HgNa, =r HgCCH^), + 2Nal. 

In order to prepare it according to this method s(j<liuni amal- 
gam containing one per cent, of the alkali met-xl is gradually 
added to a mixture of ten volumes of methyl iodide and one 
volume of methyl acetate, and the mixture shaken. In the 
first instance it is necessary that this should be well-cooled, and 
as soon as a sufficient quantity of sodium methyl is formed to 
render the mass syrupy the volatile portion is distilled olf on a 

» Wauklyn, /Vor. Hoy, Soc. (lftr»J»), x. 4. « Jomn, (.'htm, ^Vw. xvi. 41.';. 



METALLIC COxMPOUNDS OF METHYL. 251 

water-bath, and the amalgam again heated until no further 
action takes place. The products of the reaction are then 
distilled with water, and the mercury-methyl which passes over 
is shaken with caustic potash in order to decompose any ethyl 
acetate wliich may be present ; then washed with water, and 
lastly dried over calcium chloride. The part which the ethyl 
acetate plays in the reaction is not understood, it appearing to 
undergo no alteration. 

Mercury-methyl is a transparent liquid having a specific 
gravity of 3 0C9, boiling at do"", and possessing a pecuh'ar, 
rather sweetish odour, which becomes exceedingly unpleasant 
on long acquaintance. It is unalterable in the air, but can 
however be readily inflamed, and burns with a luminous flame, 
with evolution of mercury vapours. On heating with other 
metals the mercury can readily be replaced, and compounds 
are thus obtained which can only with difficulty be otherwise 
prepared. Unfortunately mercury-methyl is a very poison- 
ous substance, and a prolonged inspiration of its vapour 
produces phenomena of chronic poisoning which are afterwards 
fatal 

According to unpublished experiments* performed in the 
Physiological Laboratory of Owens College, Dr. Gamgee has 
found that, when an atmosphere saturated with mercuric 
niethide is inhaled, the respiratory movelnents of both frogs 
and mammals cease. The action is apparently one exerted on 
the respiratory centre in the medulla oblongata. There is no 
paralysis of muscles or nerves. The heart is unaffected. 

Mercury-Methyl Chloride, Hg(CH3)Cl, is formed when methyl 
iodide is heated with an excess of corrosive sublimate. It is 
also obtained by the action of concentrated hydrochloric acid 
on mercury-methyl : 

Hg I gJJ* + HCl -^ Hg I gj^3 + CH,. 

It forms colourless crystals, and yields, by double decomposition 
with silver nitrate, the corresponding nitrate, which crystallizes 
in tablets and is very soluble in water. 

Mercxcry-Methyl Iodide, Hg(CH3)I, is easily obtained by the 
action of methyl-iodide on mercury in the sunlight, as well as 
by treating mercury -methyl in alcoholic solution with iodine : 

HgiCH.,), + 1, ■'- Hg(CH,)r -f C^HJ. 



252 THE METHYL GROUP. 



It is soluble in water, and crystallizes in colourless tablets, 
having an unpleasant smell and taste. It melts at 143°, and 
volatilizes at a higher temperature. It sublimes, however, at 
the ordinary temperature of the air, and when it or the chloride 
is treated with moist silver oxide a solution of the hydroxide, 
having a strongly alkaline reaction, is obtained. 

Mcracry-Mcthyl Sulphate, {¥LgCK^^O^, is obtained in the 
form of crystals, together with marsh gas, by the action of 
concentrated sulphuric acid on mercury-methyl. 

The solutions of all these salts yield a yellow precipitate, with 
sulphide of ammonium, oi Tnercury-methyl sulphide (Frank laud.) 

167 Aluminiuvi'Methyl, A1(CH3)3. By heating methyl iodide 
with aluminium foil Cahours obtained a colourless liquid, 
which contains iodine, and is spontaneously inflammable, and 
this, when treated with zinc-methyl yielded aluminium-methyl. 
The same body is obtained more simply by heating aluminium 
with mercury-methyl. It is a colourless mobile liquid, crystal- 
lizing a few degrees above 0° to a mass of white tablets. It 
takes Are instantly on exposure to air, and is decomposed with 
great violence by water. Its vapour density at 160° corresponds 
nearly to the formula Al2(CH3)g ; it diminishes, however, when 
the temperature is raised, and at 220'' closely corresponds to the 
formula Al(CH3)8.i 

Lead-Methyl, Pb(CH3)^, was obtained by Cahours ^ by acting 
with methyl iodide on an alloy of lead and sodium, as well as 
by the action of zinc-methyl on chloride of lead : 

2PbCl2 + 2Zn(CH3)2 -^ PKCHg), + 2ZnCl^ + Pb. 

According to Butlerow,* who has carefully examined this sub- 
stance, it is a mobile liquid, unalterable in the air, and having 
a slight smell resembling raspberries. It toils at 110°, and has 
a specific gravity at O'' of 2*034, its vapour density being 9G. 
Methyl is withdrawn from this substance by the action of the 
haloid elements or their hydroxides, and crystalline salts of 
lead-trimethyl are formed. The iodide, Pb(CH3)jI, forms h»ng 
colourless needles difficultly soluble in water. When this body 
is distilled with solid caustic potash the hydroxide, Pb(CH3)30H, 
isobttiined as a mustard-like smelling liquid, solidifying to acute 
prisms, and acting as a strong alkali (Cahours). 

' Buck ton and Odling, Proc, lioy^ Soc. xiv. 19. 
' Ann. Chim. Phfs. [31, Ixii. 285. 
* Zriti*ch. Chrm. Pharm, 18tf3, 497. 



METALLIC COMPOUNDS OP METHYL. 253 



i68 Tin Tetramethyl, Sn(CH3)^, is produced when methyl iodide 
is heated together with an amalgam of tin and sodium. It is 
an ethereal-smelling liquid, boiling at 78°, and having a specific 
gravity at 13° of 1'187.^ Its vapour density is GOO. By the ac- 
tion of iodine tin trimdhyl iodide, Sn(CH3)3l, is obtained, a liquid 
smelling like mustard-oil, boiling at 170°, and having at 0° a 
specific gravity of 21 432. Caustic soda converts it into the 
corresponding hydroxide, Sn(CH3)30H, which crystallizes in 
colourless prisms, slightly soluble in water, yielding a strongly 
alkaline solution, and gives rise to crystalline salts when brought 
into contact with acids. It is volatile without decomposition ; 
but if it is heated for some time near its boiling-point it loses 

water and is converted into the oxide, O ^ o /nir^x 

( Sn(CH3)2. 

Tin Dimethyl or StannO'teiramethyl, Sn2(CH3)^. According to 
Cahours this substance is formed in the reaction already de- 
scribed together with tin tetramethyl. Ladenburg, however, 
could only obtain a few drops of a liquid which was probably 
this compound. 

Tin Dimethyl Iodide, Sn(CH3)2l2, is formed together with 
zinc trimethyl iodide when tin foil is heated with methyl iodide 
to 160^ It crystallizes in yellow oblique rhombic prisms which 
melt at 22°, and dissolve in water and still more readily in 
alcohol. It boils at 228° and is decomposed by ammonia with 
formation of the amorphous oxide Sn(CH3)20, which does not 
dissolve in water but is soluble in caustic potash and yields with 
acids a series of crystalline salts. 



OTHER DERIVATIVES OF METHYL. 

169 The methyl compounds are mono-substitution-products of 
methane. If, however, two or more atoms of hydrogen in this 
body be replaced, substances are obtained which may be regarded 
as compounds of dyad or polyvalent radicals. Though these 
belong to other groups of carbon compounds, yet they exhibit 
but slight analogy with other groups and are best considered in 
this place. 

Dichlormethane or Methylene Dichloride, Cfl2^K* ^^ ^^^ 
obtained by Regnault " by acting on methyl chloride with 

* Ladenburg, Ann. Chcm. Pharm. Siijipl. Btl. viiL 60. 

* Ann. Chim. Phyx. Ixxi. 879. 



254 THE METHYL GROUP. 



chlorine in the sunlight. It was after-rards more thoroughly 
examined by Perkin ^ and Butlerow.* It is not only formed ac- 
cording to Regnault's procc^ss, but also by treating an alcoholic 
solution of chloroform with zinc and sulphuric acid (Geuther) or 
with zinc and ammonia (Richardson, Williams, Perkin) as also 
by the action of chlorine on di-iodomethane. 

Dichlormethane is a colourless liquid boiling at 40° possess- 
ing a smell similar to that of chloroform and having a specific 
gravity at 0° of 1*360 and a vapour density of 3*012. The 
inhalation of its vapour produces the same effects as that of 
chloroform. 



Trichlobmbthane or Chloroform, CHCI3. 

170 Chloroform was discovered in 1831 by Liebig,^ who ob- 
tained it by the action of alkalis on chloral (trichlor^etaldehyde) 
and by treating acetone and alcohol with bleaching powder. 
Almost at the same time Soubeiran * obtained it by the latter of 
these reactions and termed it &her bicIUoriqtie. This chemist was 
considered to be the discoverer of the substance until Liebig* put 
forward his claim as having first prepared the compound, although 
he originally believed it to be a new chloride of carbon. It is to 
Dumas^ (1834) that we owe the recognition of the fact that the 
compound contains hydrogen, and the determination of its true 
formula.^ Regnault then proved that it is the second substitution- 
product of nielhyl chloride. 

Chloroform is likewise produced by the action of bleaching- 
powder on a large number of organic substances, but not on 
pure methyl alcohol, sodium acetate, or methyl oxalate, as was 
formerly believe<l to be the case.® (Sec Iodoform). 

rreparation. — Chloroform is manufactured on the large scale 
by warming an aqueous solution of bleaching powder with 
alcohol. Many processes are given for its manu&cture, all of 
which recommend that bleaching powder should be well stirred 
up to a thin paste with water, and this then heated with strong 
alcohol. A gowl yield is obtained when 10 parts of bleaching 

Joum. Chem. Soc. xxii. 2fi0. ' ZeiUch, Ckem. 18(J9, 27(J. 

• Pogg. Ann, xxiii. Hi ; Ann. Pharm, i. 81, 198. 

* Ann Chitn. Phys. [2], xlriii. 131 ; Ann. Pharm. i. 272. 

* Ann. Chem. Pharm. clxii. 161. 

• Ann. Chim. Phyg. Ivi. 115 ; Ann. Pharm. xvi. 164. 
' IhUL [21. Ixxi. 353. 

■ BclohonWk, Wien, Akad. Htr. Ixvi. 188. 



CHLOROFORM. 265 



powder are rubbed up with 40 parts of hot water and 1 part of 
alcohol of specific gravity 0*834 added, the temperature of the 
mixture being 65°. A violent reaction then takes place, and 
the larger portion of the chloroform distils over without further 
heating, the rest being driven over by passing steam into the 
vessel. The chloroform is then washed with water and dried 
over calcium chloride, or rectified over concentrated sulphuric 
acid. 

Of late years a large quantity of chloroform has been ob- 
tained by the action of caustic soda on chloral hydrate, which 
is now prepared on a commercial scale, formic acid being 
produced at the same time : 

CCl3.CH(OH)2 + NaOH r= CCI3H + CHNaO^ -f H^O. 

The formation of chloroform from spirit of wine cannot be 
represented by means of a simple equation. Bleaching powder 
acts upon this substance both as a chlorinating and as an 
oxidizing agent. The mass froths strongly from evolution of 
carbon dioxide, and for this reason large vessels have to be used 
in its preparation. The following ec^uation serves fairly to 
represent the principal reaction that takes place in the conver- 
sion of the alcohol into chloroform : 

3 CgH^O + 8 Ca(0Cl)2 = 2 CHCI3 + 30aC03 + COg 

+ 8 H2O -f 5 CaCl^. 

171 Properties. — Ciiloroform is a colourless mobile liquid, 
possessing a peculiar ethereal smell and a burning taste. It 
boils at 61** (Liebig, Regnault), and has a specific gravity at 0° of 
1'5252. Its vapour density was determined by Dumas to be 
4*20. Chloroform is almost insoluble in water, but is miscible 
in all proportions with ether, alcohol, and other organic liquids. 
It rejvdily dissolves phosphonis, bromine, iodine, and many 
organic substances. For this reason it is employed in analytical 
processes, as well as in the preparation and purification of a large 
number of compounds. It is not inflammable, but colours the 
non-luminous flame green, and an alcoholic solution bums with 
a smoky flame, evolving fumes of hydrochloric acid. 

This discovery of the amesthetic properties of chloroform was 
made by Sir James Simpson of Edinburgh in 1848,^ and since 

* " All. 'esthetic and other Therapeutical Effects of the Inhalatiou of Chloro- 
form," £diiir. Monthhj Jouni, of Med. Science, viii. 41.'>. 



266 THE METHYL GROUP. 



that time the inhalation of the vapour of chloroform has been 
largely practised for the purpose of procuring insensibility to 
pain in the case of surgical operations. Chloroform is likewise 
used as a medicine. 

Chloroform used for medicinal purposes must, of course, be 
pure, and this is often not the case with the commercial article. 
It sometimes contains hydrochloric acid, and even free chlorine ; 
the presence of both of these can be detected by the action of 
such impure chloroform upon litmus, as well as by the fact that it 
renders silver nitrate solution turbid, whilst the pure substance 
does not do so. If a cold solution of potassium dichromate 
in dilute sulphuric acid be coloured green by chloroform, the 
presence of alcohol or other easily oxidizable bodies is indicated. 
Pure chloroform is not coloured brown either by caustic potash 
or by sulphuric acid. It does not attack bright metallic sodium 
even at the boiling point, and if this metal should, under these 
circumstances, become covered with a white coating of chloride, 
the presence of other chlorine compounds, such as dichlorethane 
or ethylene dichloride, may be presumed. These same im- 
purities may also be recognised, inasmuch as when heated with 
alcoholic potash the impure chloroform evolves a combustible 
gas, viz. ethylene. When chloroform is evaporated on a watch- 
glass without warming it or blowing air upon it, it ought not 
to leave a residue either of water or of bodies possessing a strong 
smell. Should the latter be found to be the case, the chlorofonn 
has been prepared from alcohol containing fusel oil. 

It has already been stated that monamines can easily be 
detected by the help of chloroform (p. 162). So inversely the 
latter compounds may be employed for the detection of small 
quantities of chloroform. As the most easily obtainable amine, 
aniline is used for this purpose ; a few drops of this liquid being 
heated with the substance under investigation together with 
alcoholic caustic soda solution. The characteristic smell of 
carbamine is observed, according to Hofmann, in solution con- 
taining one part of chloroform to 6,000 parts of water. 

Chloroform undergoes a series of decompositions which will 
be described under the corresponding bodies, only a few of the 
more important being mentioned : 

(1) When heated with concentrated sulphuric acid and 
potassium bichromate, carbonyl chloride, COClg (see Vol. I., 
p. 621) is formed. 

(2) When heated with alkalis chloroform is converted into 



TETRACHLORMFniANE. -257 



formic acid, and for this reason it was tbrmerly termed formyl 
chloride : 

CHCi, + 4 KOH = CHO.OK + 3 KCl + 2H2O. 

(3) Wlien heated with alcoholic ammonia, ammonium cyanide 
is formed : 

CHCl, + 6NH3 = ON(NH,) + 3 NH.Cl ; 

(4) On treatment with bromine, brom-chloroform, CBrClg, 
is produced as a colourless li([uid boiling at 104*', which has a 
specific gravity at 0° of 2060 (Paterno, Frie<lel, Silva). 

17a TetraMcrmdhane or Carbon Tetrachloride, CCl^. This 
compound, the final product of the chlorination of niarsli gas, wiis 
discovered by Regnault^ in 1839, .and obtaincnl by the action of 
chlorine on chloroform in the sunlight. It is also fonned when 
a mixture of carbon disiilphide and chloroform is passed through 
a porcelain tube filled with pieces of porcelain heated to redness.^ 
It is best prepared by acting with chlorine gas on a boiling 
mixture of sulphide of carbon containing some antimony penta- 
chloride, the latter compound serving fis a carrier of I'hlorine. 
The liquid is then distilled, and the portion boiling under lOO** 
separated and treated witli boiling caustic potash in ortler to 
remove chloride of silver, trichloride of antimony, and undecom- 
posed carbon bisulphide.' Tetrachlormethanc^ is also formed 
when chloroform is heated with chloride of io<line to 160** — 170° 
(Hpfmann). 

It is a colourless liquid boiling at 78", having a specific gravity 
at 0** of 1*6298, and possessing a smell similar to that of chloro- 
form. Its vapour has a density of 5*24 (Kolbe). 

Dibrommethane or Methcne Dihromidr. CH.,Br.„ is formed 
by the action of bromine on the corresponding io<lidc, and 
together with tribrommethnne by acting with bromine on 
methyl bromide for some hours at a temperature of 150°. It 
is a liquid which boils at 80''-82'* and at ll°r) has a specific 
gravity of 2*0844,* its vapour density Ix'in/ .") 0.") (Steiner). 

173 Tribrommethanc or Bromoform, CHBra. This compound 
was discovered by Lowig,^ in 1832, who prepared it by de- 
composing bromal (tribrom-acetaldehyde) witli aqueous alkalis. 

* v^wn. Chim, Phys. Ixxi. 377. ' K«»Hx', ,//*//. Chcm. Phann.\\y. 41 , 
' Hofmann, Chan. Soc. Juuni. xiii. &2. 

* Steiner, Ber, Deufsch. Vhrm. Or^. vii. 507. 
^ Ann. Phami. iii. 29.1. 

VOL. III. 8 



258 THE METHYL GROUP. 



Lowig considered it to be a bromide of carbon, but Dumas * 
ascertained its true composition, and obtained it by the action 
of bromide lime upon spirit of wine, or on acetone. It is also 
produced when bromine is added to alcohol, or better, when 
bromine is poured into an alcoholic solution of caustic potash. 
It is likewise found in crude bromine.^ Bromoform smells 
and tastes like chloroform; it boils at 149°-150'', and has a 
specific gravity at l^'^'b of 2775,* and a vapour density of 
8-63 (Cahours). 

Tetrab7'07nmethane 07* Carbon Tetrahromide, CBr^, was discovered 
by Bojus and Gi oves * and is formed by heating carbon disulphide, 
bromoform, iodoform or bromopicrin with bromine in presence 
of bromide of iodine or certain metallic bromides. 

In order to prepare it, 2 parts of carbon bisulphide, 14 parts 
of bromine and 3 parts of iodine, are placed in a sealed tube and 
heated for 48 hours to a temperature of 250'', and then the 
contents of the tube distilled with caustic soda. When water 
is added to a mixture of bromoform and bromine, tetrabrom- 
methane is also fonned on exposing the mixture to daylight; 
but the reaction only takes place slowly, whereas if some 
caustic soda be added, it proceeds much more rapidly, inasmuch 
as the hydrobromic acid formed is at once neutralized.^ 

It crystallizes from hot alcohol in white glistening tablets, 
which have a sweetish taste, and an ethereal smell. It has a 
specific gravity at 14° of 3*42, fuses at 91°, and boils with 
partial decomposition at 189*''5. It may, however, be sublimed 
without change by careful heating. 

174 Di-iodomctlmne or Methylene Di-iodUley CHgIg, was first 
prepared by Butlerow ® by acting on sodium ethylate with 
iodoform. This chemist showed that the body formerly ob- 
tained by Brlining by the action of iodoform on caustic potash 
is identical with this compound. It is also formed when 
chloroform is brought in contact with concentrated hydriodic 
acid : " 

CHCls + 4 HI = CHjIj + 3 HCl + I^. 

This bcxly, wliich is used for the preparation of several other 

» Ann. Chim. Phy$. [2], Ivi. I'JO. 

^ Hermann, ^mji. Ch-m, Phann, xcv. 211. 

3 Sclimidt, Ber. DeuOtch, CKem, Oea. x. 193. 

* Chcm, Soc. Jonrn. xxiii. 164, 161 ; xxiv. 773. 

* Habermann, Ber. Drutsch. Chftn, Otn. vi. 549. 

* Ann. Chem. Pharm, cvii. 110; cxi. 242. 

" Lwb«n, ZfUiith. Chem. 1868, 712 ; BIjuducho. Ibid. 1S71. 258. 



lODOFOR^r. 259 



compounds, is, however, best obtained by the following method 
proposed by Baeyer.* An upright condenser is fixed to a liter 
flask by means of a wide tube, the upper end of which is 
connected with a T-tube, so that the materials can be brought 
in by the one limb whilst the hydriodic acid formed can escape 
by the other. 200 grams of hydriodic acid, having a boiling 
point of 12T*, are brought into the flask, and to this 50 grams 
of iodoform are added, and the mixture is then heated to the 
boiling point, and phosphorus added little by little until no 
further evolution of iodine takes place. Then 100 grams of 
iodoform and the necessary quantity of phosphorus are 
added alternately. The formation of the di-iodomethane is ex-' 
plained by the following reaction : 

CHI3 + HI = CH^Ig + Ig. 

Di-iodomethane is a yellowish strongly refracting liquid, boiling 
with partial decomposition, at 181°, solidifying to glistening 
tablets at 2°, and possessing a specific gravity at 5** of 3*342. 

175 Tri'iodmnethane or Iodoform , CHI3. This compound 
was discovered by Serullas^ in 1822 and termed by him 
** carbide d*iode." It is to Dumas^ that we are indebted for first 
pointing out that this compound contains hydrogen. There is 
no substance in which the hydrogen can be so readily overlooked 
as in this, for iodoform of all known compounds contains the 
relatively smallest quantity of this element, namely 0*26 per 
cent 

Iodoform is formed by the action of iodine upon alcohol in 
presence of the caustic alkalis or their carbonates. Instead of 
alcohol a number of other substances may be used ; these will 
be mentioned hereafter. A number of processes are given for its 
preparation ; the following, recommended by Filhol,* is usually 
employed. Two parts of crystallized carbonate of soda are 
dissolved in ten parts of water, one part of alcohol poured into 
the solution, and then one part of iodine gradually added to 
the liquid heated to 60°-80*', when iodoform gradually begins to 
separate out. The liquid is filtered, and the above mentioned 
(juantity of carbonate of soda again added to the filtrate heated 
to 80**. Chlorine is then passed into the liquid, which is shaken 
from time to time, the object being to decompose the iodide of 

* Ber, Deutsch. Chein. Oes. v. 1094. 

* Ann. Chim, Phys. [2], xx. 165 ; xxii. J 72 ; xxv. 311 ; xxxix. 230. 
» lUd, IvL 122. ♦ Journ, Pharm. vii. 267. 

S 2 



i*'*i» TIIK MKTITYL GROUP. 



SiVili\nn wliirli i> t^viuiNi. :uui to obtain the iodine in a £>e!r 
t)i\i.liul ^t•)(r Wlu^n no more iodoform separates am 
current o\' ihlovnto im Mopixni, tlio liquid allowed to 
it Invonu's roIo\itIrss. i\\\\\ thou, on cooling, theiodofonn 
ou a tilUT iuul \\it^)uHi with oold water. 

A gi^Hl vioKl is aiNo oht-ainod by warming toge^sba Hat 
follow iui^ oonsiittionijt until tito liquid becomes 
i^^line. S:2 ]vu'ts; iH^tJiMsiutn oarUmato, 32 parts; 95 
al'/obol. li»)vii*t.s; Avatvi S() f^vrt.s. The liquid is then pooTBd 
off from thi* iiviot'onn whioh is (io)H)sited, and the foUowixig is 
cviJcJ to tholiqniii: )>otjuss\nm diohromate 2 to 3 parts^ hjdio- 
c:.joric aoivl li» to l*i |vut,s. This 8t>rves to decompose the 
irjhkZf: and iinliilo nnd to liln^nUo iinline. The whole is then 
r.ei:r:Jizeil hv tho !ul«liiiou of :i2 {kuI.s of carbonate of soda» 6 
j/^r.i: '.f i«:Klino, and \k\ \M\\'ts of* ahnthol. the liquid again panned 
/ff from the iixlofonn. and thcst' o|>oralions repeated until the 
.>^'iid contaius tint hu^o a ipiantitv of salt in solution.^ The 
f'/nfiAiiun of iiHlofonn is i\'j«\»si»nt4Hl hv the following equation: 

rif,CH^0H + 4L^ i\K.n\ iMn, + OHKO, + 5KI + 5H,0. 

In luJditiuu to this. oXhvY jmnhtits ai\» fonneil, such as potas- 
^ilirfJ i<i<Iate. acetic ethrr. Ac. 

I'>iof<»nn is insoluble in water. b\it dissolves readily in alcohol, 
'TVbtallizing from this menstni urn in largi* lemon-yellow bright 
hix-isided tables whieh melt at XW^' and sublime when strongly 
Le:jite<l. undergoini; {Kirtial iiei*onq>osition with formation of iodine 
\ajxjurK. It may, howtxrr, Ih» volatiliziHl without decomposition 
iji u current of steam. It (Htssessi's a si)tVron-like smell, and a 
hv.<-i.-t t*»st4.\ In the ywYv state* it diH»s not \uulergo alteration on 
<-x|><iMire to ii^lit. but its s«>hition in bisulphide of carbon is ex- 
cessively sensitive to hj^ht, quirk ly lHH*t>ming iH>loured violet 
owiij;^: to sejianitiou n( free imline.- 

It has alreadv been mentioned that manv other bodies, in 
addition to aleohol, yield iodofi»rm. Amongst the simpler of 
thes<*, ethyl ether an<l jicetic acid have fn^quently been classed. 
Liebeu,^ in a very complete series of exiHTiments, has, how- 
ever, shown that these substam-es, if perfectly pure, do not 
vield the slightest trace of iinlofonu. On the other hand, the 
nonnal primary and si'Condary alcohi»l9as well as their aldehydes 

> I'hnnn. Jouni. Trans. [rJ], iv. riS»3. 

- HuTnln-rt, ./. urn, I'nann. Chim, |.M], x\ix. S.'2. 

' yimi. f%t". P/i(i -i'l, Su|»|il vii. '.M^ ami o77. 



NITROCHLOROFORM OR CHLOROPICRIN. 261 



and ketones all yield iodoform, but their isomerides do not 
Hence the formation of iodoform serves as an excellent means 
in many cases for ascertaining the purity of these bodies, and 
also as a test for their presence even in very small traces. 
Thus, for example, if water containing only T^nnr^^ P*"^ ^^ alcohol 
be gently warmed with crystals of iodine, and then caustic soda 
added, and the liquid allowed to stand for some time, a distinct 
precipitate is observed, and this when examined under a micro- 
scope exhibits the six-sided tablets or stellar crystals characteristic 
of iodoform. 

Iodoform possesses anaesthetic properties, acting especially on 
the muscles. It is used as a medicine and has been employed for 
outw^ard application, especially in cases of cancer. 

Chloriodoform, CHIClg, is a yellow oily liquid, boiling at 131*, 
obtained by heating iodoform with the chlorides of lead, mercury 
or tin. 

Tetra-iodomethane ar Carhmi Tetra-iodide, CI^, was obtained 
by Gustavson ^ by acting on aluminium iodide with tetrachlor- 
methane in presence of carbon disulphide. It crystallizes in 
large regular octohedroDs, which decompose slowly in the air 
at the ordinary temperature, but quickly at 100°, into iodine 
and carbon. 

176 CMoniUrom^thave, CH2C1(N02). To prepare this com- 
pound, sodium nitromethane is brought in small quantities into 
saturated chlorine water, and when no further action takes place 
the mixture is distilled. It is a colourless oily liquid, having 
a penetrating smell, boiling at 122°-123°, and possessing a 
specific gravity at 16° of 1*466. It easily dissolves in alkalis, 
and gives the nitrolic acid reaction like other primary nitro- 
compounds (see p. 171).* 

177 Tricldoi'nitroTrutlmiie, Nitrochlorofoi-^n, or Chloropicrin, 
CCl^{l!^0^, was discovered by Stenhouse,* who obtained it by 
distilling an aqueous solution of picric acid (trinitrophenol), 
CgH2(N02)s.OH, with bleaching powder. Its correct composition 
was first recognised by Gerhardt.* Chloropicrin is also formed 
by a similar reaction from many other aromatic nitro-compounds, 
and may also be prepared as Geisse ^ has shown, by the following 
reactions : 

' Coinpt. Reiid. Ixxviii. 882. 

- Tschemiak, Ber. Dcutsch. CJum. (Jes. viii. 608, 

3 PhU, Maq. [3], xxxiii. 53. 

< Compt. Rend Trav. Chivi. 1859, 34. 

' Ann. CJirm, Pliann, cix. 282. 



'ic,t THE METHYL GROUP. 



{\) Cyhloral (trichlordcctaldehyde) is distilled with fuming 
iiiiri<; a<'i(l : 

i)i\yA)\\ + 3HO.N02= CCIjCNO,) + 2H,0 + CO,+N,0,. 

it) Methyl alcohol is heated with nitre, common salt, and 
Mil|iliiiri<; acid : 

i\\\j^)\\ + NO^OII + 201^ = CClaCNO^ + 2H,0+HCL 

(\\) Alroliol and <'ommon salt are distilled with nitric acid. . 
It JK likowiw; obUiiucd, though with greater difficulty, by 
iH'utiiig ('hloi'oforiii with concentrated nitric acid :^ 

(;ilC:i, 4- NO^-OH - C(N02)Cl3 + H,0. 

Ai'^/idiii^ \m ilofiiiann''' the following is a useful method of 
|^i<r|Miiiii.ioii : ."»() kilos of freshly-prepared bleaching-powder are 
uk\i^i'A to It thirk |>iiHto with cold water and placed in a still 
teiiiii/iiii<|i'<l l»y cold water. To this, a saturated solution of 
\it kilo.i of |)icri(: lU'id heated to 30"" is added. After a few 
wwwwVi-^ ii violnit rcfu'tion tiikos place, and the greater part of 
\\\i: « liloio|iiriiii iliMtilH «»vi!r. The remainder is driven oflF by 
li'Mitiiipf thn nlill 

riiloiopii'iiii JN a mobile liquid, boiling at 113^ having a 
blHriiir ^mvily ol' I (l(ir»7, and possessing a very penetrating 
MiiH'll ii'ioiiibliii^^ that of chloride of cyanogen. Its vapour 
iM'i.i |H»woi fully oil ihn fyoH and mucous membranes, but the 
iiritiition ilocM not Inst lon^. IIeate<l in tlie form of vapour it 
(Icconi|Hm('H with explosion. It is insoluble in alkalis, and is 
not atUicki'il by Hulplmric or nitric acid even when boiled. 
When treaU^d with iron filings and acetic acid it is converted 
into methylamine : 

CCIjCNOJ \- 6Hj = (JHjCNH.^ + 3 HCl 4- 2H2O. 

Heated with ammonia under pressure it yields guanidine* 
(Vol. I. p. G80) : 

C(N02)Cl3 + 7 NH3 - CXNH)(NH2)2 4- 3 NH.Cl + 2 Hp + >%. 

Dichlordinitrometluinc, ^^^(NOj)^, was di.'^covered by Mari- 
gnac,* who obtained it by distilling naphthalene tetrachloride, 

' Mills, Joum, Chem. Sor, xxiv. 641 ; Coma, Gas. Chim. Ital. 1872, 181. 

' Chem, Sor. Joum, xix. 249. 

' Hofriiano, B^r. Dfu'srh. f'hew. ^V« i. I4f>. 

* Jjin. '"hr.ii. rhnrm. xxxviii. 14. 



TRINITROMETHANE OR NITROFORM. 263 



Cj^HgCl^, with concentrated nitric acid, and hence it was 
formerly known as " Marignac's oil." It is a colourless liquid, 
smelling like chloropicrin, and having a specific gravity at 16° 
of 1'685. It is easily volatilized in a current of steam. 

Manobramnitromethane, CH2Br(N02), is formed by the action 
of bromine on sodium-nitromethane. It is a colourless, very 
strongly-smelling liquid, boiling at 146°-14T', and is soluble in 
alkalis. 

Dibromnitromethaiiey CHBr2(N02), is obtained by the action of 
bromine upon a freshly-prepared solution of the foregoing com- 
pound. It is an oily, strongly-smelling liquid, which decomposes 
on distillation, and possesses acid properties.' 

Tribromnitromethane or Broinopia^in, CBr3(N02), was obtained 
by Stenhouse ^ by distilling a solution of picric acid with bromide 
of lime. It is also formed when nitro-methane is treated alter- 
nately with bromine and caustic potash.* It is a liquid closely 
resembling chloropicrin, and when strongly cooled forms prismatic 
crystals, melting at 10*''25. Its specific gravity at 12°*5 is 2*811. 
It may be distilled in a vacuum without decomposition, but 
decomposes even when carefully warmed under the ordinary 
circumstances with formation of tetrabrommethane, carbon 
dioxide, the oxides of nitrogen, and other bodies.* 

Chlordibromnitromethane, CClBr2(N02), is obtained when 
chlomitromethane is dissolved in caustic potash and bromine 
added. It is a liquid possessing a similar smell to chloropicrin, 
having at 15° a specific gravity of 2421, and being volatile in 
a current of steam .^ 

178 Trinitrom^tliaiu or Nitroform, CH(N03)2, was discovered 
by Schischkoff^ in 1857, who prepared it by heating trinitro- 
acetonitril with water. This substance dissolves with violent 
evolution of carbon dioxide, and the yellow solution contains 
the ammonium salt of trinitromethane : 

{ CN ^"^^ + 2 H2O = C(N02)3NH, 4- CO2. 

Under certain conditions, which are not well understood, this 
action of water on trinitroacetonitril may be accompanied by 

^ Tschei'uiak, Bet. DeuUtch. Ckem, Gis. vii. 916. 

- Phil. Mag, [4], viii. 36. 

' V. Meyer, Bcr, DetUsch, Cliem. Ges. \aii. 816. 

* Bolas and Groves, Jaum. Ckcm. Soc. xxiii. 153 ; xxiv. 773, 

^ Tscherniak, Bcr. Dctctuch. Chon. Gca. viii. 608. 

^' Ann. Chm. Phorm. ri. 213 ; riii. 364 : rxix. 247. 



fM THE HETHYL GKOUP. 



leriofu expktfknuL^ On eTipondon ihe sah sepumtes oat in 
jellow moDoduiic prisms. If dihite caosde potaaii be used 
instead of vater, the jellow ciTBtaDine polaainm ttlt is ob- 
tained ; and if solphmic add be added to anj of these salfts* 
nitrofbrm separates oat in a liquid lajer, which on coding 
stdidifies to a mass of laige obliqae crjrstalsu It has a bitter 
taste and disagreeable 8ii»ell, is t^t inflammable, and when 
wanned begins to decompose under IWf with rapid eTolation 
of gas, exploding violendy when qoicklj heated. Its yellow 
salts are also eTflotive, and frequently decompose spcxitaneously 
with evolution of ga& 

When a mixture of nitroform and bromine is exposed to sun- 
light, bromnitro/orm, C(NO,)^r, is formed as a colourless liquid, 
which crystallixes at 12^ and is decomposed at 140^ but may be 
▼olatiliied in a current of steam. 

Tetmniiromethane, C(SO^^, is formed when a continuous 
current of air is passed through a mixture of nitroform, con- 
centrated sulphuric add, and nitric add heated to 100^ On 
addition of water to the distiUate, this compound separates uiit 
as a colourless mobile liquid, which crystallizes at 13^, boils at 
12(r, and is neither explosive nor inflammable. If, however, it 
be dropped on to glowing charcoal it bums with a bright flash. 

179 Metheru Digulphonic Acid, CH^(SOJS)^ This compound, 
which was formerly called methionic acid, was first prepared by 
Licbig,^ together with other products, by the action of sulphur 
trioxide on ether. Buckton and Hofmann' obtained it by 
treating acetonitrii (methyl cyanide) with concentrated sulphuric 
add, acetic add, carbon dioxide and ammonia being formed 
at the same time. It may also be obtained from sulphoaceUc 
acid, acetamide, and lactic add, and also by heating chloroform 
with a solution of potassium sulphite.^ In this case, methene 
dichloride is first formed, which is then converted into potassium 
methene dinulphonate : 

(a) 2 CHCl, + 3 K^SO, + H,0 = 2 CH.a, + 2 K,SO^ + 2KC1 + SO^ 

{h) CH,a, + 2 K^, := CH,(SO,K), + 2 KCl. / 

The free acid is best prepared by the action of sulphuretted hy- 
drogen on an aqueous solution of the lead salt. On evaporation 

' V. Meyer, Ber, DeulsrA. Chfm. Ges. vii. 1744. 

* Ann, rharm. xiii. 85. 

* nkem Sor. Joitrn. iz. 241. 

* Stn'ckfT, Ann, Chem. Pharm. cxlviii. 00. 




METHINE TRISULPHONIC ACID. 265 



in a vacuum it may be obtained in the form of a deliquescent 
striated crystalline mass. It is a very strong acid, and forms a 
series of well crystallizable salts. 

Methine Triaulphonic Add, CH(S03H)3, is formed when dry 
calcium methyl sulphate is heated to 100'' with a large excess of 
fuming sulphuric acid. The free acid is obtained by decompos- 
ing the lead salt with sulphuretted hydrogen; it forms long 
deliquescent colourless needles, and is a tribasic acid. It decom- 
poses chlorides and nitrates, and forms well crystallizable salts. 

Fbtasaium Methine Trisulphoriate, CH(S03K)3, crystallizes in 
small hard glistening prisms, and is formed when chloropicrin is 
heated with a concentrated solution of potassium sulphite. As 
an intermediate product potassium nitro-methene distdphancUe, 
CH(N02)(S03K)2 is formed as a crystalline slightly soluble 
powder which deflagrates on heating.^ 

Barium Methine Trisulphonate, [CH(S03)3]2Ba3, crystallizes 
from boiling water in glistening tablets. Its solution throws 
down the insoluble lead salt from a solution of acetate of lead.^ 

Methyl-mercaptan Trisulphonic Add, C(S03H)3SH. If bi- 
sulphide of carbon be treated with manganese dioxide and 
hydrochloric acid, a reaction takes place which becomes more 
rapid on the addition of a small quantity of iodine ; and besides 
thiocarbonyl chloride, CSClg, and trichlor-methyl sulphonic 
chloride, CClg-SOgCl, the compound, percMar-methyl mercap- 
tan, CCI3.SCI, is fonned. This latter compound is a golden 
yellow, very powerfully-smelling liquid, boiling at from 146'' to 
147°.* It acts on an aqueous solution of potassium sulphite 
giving rise to the salt C(S03K)3SH, which forms large, hard, 
colourless triclinic crystals. The same salt is formed by the 
action of potassium sulphite on thiocarbonyl chloride : 

CSClj -f 3 K2SO3 -f H2O = C(S03K)3SH 4- 2 KCl + KOH. 

It gives a white precipitate with basic lead acetate, from 
which the free acid can be obtained by treatment with sul- 
phuretted hydrogen. In a concentrated state this forms a 
thick very deliquescent ayrup. Its dilute solution gives a deep 
blue coloration with ferric chloride. The free acid and its 
salts are readily decomposed in presence of water, with forma- 
tion of sulphuric acid and viethyl-mcrcaptan-disulphonic acid, 

' Kuthke, Ann, Cfum. Pfiaj^n. clxi. 149 ; clxvii. 219. 
- Thcilkuhl, Ann. Chem. Pharm. cxlvii. 134. 
^ Ratlike, Bcr. Dcutsch. Chnn. Gcs. iii. 858. 



206 THE FORMYL GROUP. 



CH(S03H),SH. This forms crystallizable salts, and is a dibasic 
acid. The hydrogea which is combined with the sulphur can, 
however, be replaced by metals possessing a strong aflSnity for 
sulphur, such as lead. This is not the case with the trisul- 
phonic acid. By the action of nitric acid on the potassium 
salt of the latter compound potassium methyl oxytrisulphonate, 
C(S08K)30H, is formed, crystallizing in strongly refracting 
monoclinic prisms. The free acid is a deliquescent mass, and 
the salts crystallize well.' 



THE FORMYL GROUP. 

Formic Aldehyde, COHg. 

i8o This interesting body may be regarded as the aldehyde 
and ketone of formic acid, or as the oxide of the dyad radical 
methene. Many attempts to prepare this substance have been 
unsuccessfully made, inasmuch as the oxidizing agents usually 
employed for the preparation of aldehydes yield at once formic 
acid. Hofmann was the first, in 1867, to succeed in pre- 
paring the substance by passing the vapour of methyl alcohol 
together with air over ignited platinum. For this purpose he 
employed the following apparatus. A three-necked flask of 
about two liters capacity is filled about five cm. high with 
warm methyl alcohol. One of the necks of tlie flask is 
furnished with a cork, and a tube which passes to the surface 
of the liquid. The other necks are furnished with open glass 
tubes ; the middle one carries a spiral of platinum wire fastened 
to a loosely-fitting cork, the spiral being brought nearly to the 
surface of the methyl alcohol. The third opening is connecte<l 
with the upper end of the condenser, the lower end of which is 
fastened into a two-necked receiver; this receiver is in its turn 
connecteil with a series of wash-bottles, and the last of these 
communicates with a water-jet aspirator, by which a rapid current 
of air can be dniwn through the whole system. The platinum 
spinil is next heated and lowered into the bottle, when the 
flameless combustion of the methyl alcohol begins to manifest 
itself by the evolution of vapour powerfully affecting the nose 
and eyes. Gradually the tempeniture of the apparatus rises 
and drops of a colourless lic^uid are soon rondeiised in the 

' Albrorht, .luii. Chem. Vhnmi. dxi. 12i». - /V^-. /»W. Sf*>'. wi. l.'.t;. 




FORMrC ALDEHYDE. 267 

-, anil if the apj^ratus be properly constructed a solution 
of aldehyde in dilute methyl aIc;)hol is obtained 
whilst the portion which is not collected here 
passes into the wash-bottles. At the begoinnig 
of tiie experiment a sharp explosion sometimes 
takes place, which drives the cork with the 
spiial out of the bottle. In order to prevent 
this, an improved apparatus has been su^ested 
by Volhard.' This consists of a Davy's glow- 
lamp shown in Fig. 67, tilled with methyl 
alcohol, over which a funnel is placed connected 
with a condenser as before. A stream of air 
can now be regulated so that the ignition of the platinum 
spiral is not visible in the daylight. 

The solution of aldehyde, prepared by one or other of these 
means, only contains about 1 per cent, of formic aldeliyde. In 
order to prepare a more concentrated solution, a regulated 
mixture of air and methyl alcohol vapour is passed through a 
tolerably wide platinum tube contiiiuing a bundle of iiue 
platinum wires. By gently heating this, a current of formic 
aldehyde is obtained. This can be condensed to a liquid, which 
however does not contain more than 5 per cent, of aldehyde ; 
biit this apparatus when in proper action may be kept going 
for several months without intermission. If the methyl alcohol 
be driven out of the solution by distillation a certain amount of 
aldehyde passes over with it. A better plan is to expose the 
residual liqiiid repeatedly to a freezing mixture, the ice formed 
being each time removed ; the residual liquid contains 10 per 
cent of formic aldeliydc.^ 

A solution of formic aldehyde possesses a very penetrating 
smell, and when warmed with ammoniitcal silver solution, a 
mirror-like deposit of metallic silver is formed. Ammonium 
formate is in this case produced. Up to the present time the 
separation of the aldehyde from its solution has not proved 
possible. If it be evaporated in a vacuum over sulphuric acid, 
part of the aldehyde passes into the state of vapour with the 
water, whilst another portion assumes a polymeric modification.' 
i8i Para/ormaldekyde, C^H^Og, has been known for some 
time, and was first obtaineii by Butlerow,* by acting on silver 

' Ann. Clicm. ri'a.ui. clixvi. 128. 

' Hofmann, Ber. PriiMi. Vhcm. 6rv. li. 1GS.1. ^ Ihi't. ii. 153 



268 THE FORMYL GROUP. 



oxalate with methene di-iodide, and was described as dioxy- 
methylene: 

3 CHjI, + 3 AggCgO, = CjH^Og + 6 Agl + 3 CO^ + 3 CO. 

This substance is, however, best prepared by heating glycollic 
acid with sulphuric acid to 160**, when it sublimes: 

3 CH,(OH)CO.OH - 3 CjHeOg + 3 CO + 3 H^O. 

Paraformaldehyde is a white indistinctly crystalline body, 
which is insoluble in water, alcohol, and ether. It possesses no 
smell and sublimes at 100^ melting, however, at 152^. Heated 
more strongly it dissociates into three molecules of formic alde- 
hyde, the irritating smell of the gas being at once perceived. 
If this gas be collected over mercury and allowed to cool, it 
gradually disappears with formation of the trimolecular form. 

Wheu paraformaldehyde is heated with much water in a 
closed tube to 130''-150'' it enters into solution again, splitting 
up into the simpler molecule. This solution does not under- 
go change in absence of air, probably because the aldehyde 
is combined with water, methylene alcohol, CHjCOH),, being 
formed. 

Farathioformaldehyde, CgH^Sg, was first described by Girard,^ 
who obtained it by the action of nascent hydrogen on carbon 
disulphide. It has likewise been prepared by heating methene 
di-iodide with sodium sulphide,' as well as by treating the 
solution of formaldehyde or the para-compound with sul- 
phuretted hydrogen, and then heating with hydrochloric acid. 
It is also formed by treating thiocjranic acid with nascent 
hydrogen : * 

CH, 



A 



3SCNH + 6Hj = I I 4- 3NH,. 

ILC CH, 

S 

This compound crystallizes in a shining white crystalline mass 
which melts at 216°. It combines with silver nitrate to form 
the crystalline compounds C,HjSj + AgNO, and CgH^S, + 
SAgNO,, whilst with platinic chloride it forms yellow needles 
of 2 CjHeS, + PtCl^. 

* Comjifn/ Jlf-ndusy xliii. 306. ' Iliujciiiaiin, Ann. Chem. Pharm, cxxri. 201. 

3 Ilijfniunu, ZciUch. Chcm, [2], iv. 689. 



FORMIC ACID. 269 



FORMIC ACID, 

x8a In the sixteenth century Brunfels, and at the beginning 
of the seventeenth Baukin, noticed that red ants have the 
power of emitting an acid liquid which turns vegetable blue 
colours red. Formic acid was first obtained by John Ray 
in 1670, by distilling red ants, and he observed that this 
substance has the power of forming with white lead a kind 
of sugar of lead, which, like ordinary sugar of lead, pos- 
sesses an astringent taste. Hence he concluded that the acid 
in question is similar to acetic acid.^ About the same time 
a German chemist, Samuel Fischer, is said to have pre- 
pared formic acid. These observations were confirmed by 
Hiame, Homberg, and Marggraf, the latter of whom found that 
this acid does not precipitate the salts of silver, lead and 
mercury, or nitrate of lime, and he adds that this shows that it 
is neither hydrochloric acid nor vitriolic acid. Calx of silver 
however dissolves in it, and calx of mercury on being warmed 
with it yields metallic mercury.^ From this time forward, the 
acid compound obtained from ants was looked upon as a 
peculiar acid. Arvedson and Oehm described the acid and its 
salts more exactly in a Dissertatio de addoformicarum in 1777, 
but even in 1802 it was stated by Fourcroy and Vauquelin ithat 
it was simply a mixture of acetic acid and malic acid. This 
statement was however contradicted by Suersen in 1805 and by 
Gehlenin 1810. 

In addition to its occurrence in ants, this acid is also found in 
bodies of a caterpillar {Boinhyx processionea), in common stinging 
nettles, in the fruit of the soapnut-tree (Sapindtis saponaria), in 
tamarinds, and in shoots of various pines. It also occurs in small 
quantity in various animal liquids, as sweat, urine, the juice of 
muscle, &c. It is remarkable that this substance occurs together 
with other fatty acids in the putrefaction of diabetic urine, and 
that it occurs together witli acetic Jicid and other homologues in 
small quantities in various natural mineral waters. It is likewise 
produced in the dry distillation of various organic substances, 
as well as by the oxidation of a large number of such bodies. 

In his investigation on manganese in 1774 Scheele remarks 

» Phil. Trans. 1670, Jan. 13. * Bfriiu Akad. 1749. 



♦270 THE FORMYL GROUP. 



that when a mixture of this substance and sulphuric acid is 
Iieated with sugar or gum an acid vapour is evolved which when 
<'ollected in a receiver turns out to be vinegar. Westrumb then 
mentions in 1785 that acetic acid is produced by the dephlo- 
gistication of tartaric acid by means of oxide of manganese, 
upon which Dobereiner in 1822 showed that the acid produced 
in this reaction is really formic acid. This observation gave rise 
to the process for its artificial production. 

Starch was found to be the best material for the preparation 
of this acid, and, according to Liebig's receipt, 100 parts of 
starch, 370 parts of finely-divided oxide of manganese, and 300 
parts of water are mixed together, and 300 parts of concen- 
trated sulphuric acid added to the mixture whilst it is being 
stirred. By careful distillation the strongly frothing mixture 
yields about 33o parts of dilute formic acid, of which 100 parts 
saturate 15 parts of dry carbonate of sodium. This method, how- 
ever, as well as other similar processes are now no longer used, 
formic acid being always prepared from oxalic acid, which, when 
heated, splits up directly into carbon dioxide and formic acid : 

Gfifi, = CO, + CHjO^ 

Gerhardt found that, when oxalic acid is mixed with fine 
quartz sand, a better yield of formic acid is obtained, but even 
in this case, and especially when the oxalic acid is heated 
alone, a large quantity of oxalic acid passes over undecom- 
posed, whilst a part of the formic acid decomposes with 
formation of carbon monoxide and water. On the other hand, 
the above reaction takes place much more completely if the 
oxalic acid be carefully heated with glycerin. On this observa- 
tion Berthelot has founded a method which now has come into 
general use for the preparation of formic acid, the details of the 
process having been carefully worked out by Lorin. According 
to this method, anhydrous glycerin is gradually heated with 
crystftllized oxalic acid to a temperature of 75*'-90'' until the 
whole of the carbon dioxide has been evolved. Oxalic acid is 
Again added and the mixture heated as before, this process 
being capable of repetition for any number of times. At the 
beginning of the reaction very dilute formic acid passes over, 
and this becomes stronger on each addition of oxalic acid until 
at last a liquid containing 56 per cent, of the acid distils over. 
Crystallized oxalic acid, CgH^O^ + 2YI/), first decomposes into 
water,fiHhD|^dioxide, and formic acid, which in the nascent 




SYNTHESIS OF FORMIC ACID. 271 




+ COH.OH = CA- 



s-"« 



state acts upon the glycerin, CjH5(0H)j, with formation of 
monofonnyl ether or monoformin : 

roH 

OH + HjO. 
lO.COH 

If oxalic acid be again added, the water of crystallization 
decomposes a part of this ether with formation of formic acid 
and glycerin, but, at the same time, a fresh quantity of the 
ctber is produced, and this continues until the liquid is 
saturated with monoformin, at which point both reactions 
take place simultaneously, and the acid of the above strength 
distils over. If anhydrous oxalic acid be employed, the 
reaction begins at 50'', and is accompanied by violent frothing ; a 
dilute acid first distils over, triformin, CsHj(CH02)3, is formed 
which soon saturates the liquid, and an aqueous formic acid, 
containiDg from 87 to 88 per cent, of the pure acid, distils 
over. When, however, a certain quantity of oxalic acid has 
been employed, the normal reaction does not hold good. 

In place of glycerin many other polyatomic alcohols may be 
employed for the preparation of formic acid from oxalic acid. ^ 

183 Synthesis of Formic Acid. The various methods for the 
synthetical formation of formic acid are of great theoretical 
interest. 

(1) Berthelot has shown that it is formed when carbon mon- 
oxide is treated with caustic potash or other alkalis : 



CO + g}o = ^^5}o. 



This reaction requires about seventy hours to complete it at a 
temperature of 100°, whilst it is completed in ten hours at a 
temperature of 220°.^ According to Merz and Tibirica,^ the 
action proceeds more quickly when moist carbon dioxide is 
passed over porous soda-lime loosely arranged in large U-tubes, 
and heated to about 200° in an oil-bath. Above 220° decom- 
position commences, with evolution of hydrogen and formation 
of carbonate. 

(2) When moist carbon dioxide (which may be regarded as 
carbonic acid) acts upon potassium at the ordinary temperature, 

^ Loriu, Bull. Sor. Chim. [2], v. 7, 12; xx. 2il ; xxiv. 22 and 436. 
^ Ann. C/ir.m. Pharm. xcvii. 12r» ; Compt. Jfrml, xli. 9f)5. 
5 Bcr, Jkutsch. Chem. Gcs. x. 2117, IhUl. xiii. 23. 



:«:: 



THE rORMYL GROUP. 



a mixtore of potaaBimi caibooate and puUeinm fonnate is 
produced:* 

(3) In a nmilar way, sodium fomiate is produced when a 
' uriution of carbonate of ammonia is treated with sodium 
amalcam.* 

(4; If carbon disulphide be heated with water and iron borings 
at 100^ kmfUB fcvmate is produced, together with sulphide of 
iron, carbon dioxide, and other bodiea' 

(5; A small quantity of the acid is likewise formed by the 
direct union of carbon dioxide and hydrogen under the influence 
of the silent electric dischaige. Thus, if the electric dischaige 
be paved through the mixed gases by a Siemens induction- 
tube, small drops of an add liquid are formed, together with 
carbon monoxide and a small quantity of marsh gas, this liquid 
exhibiting the chaiacteristic reactions of formic add.^ 

(6) Hydrocyanic acid, HCN (Vol. I. p. 659), is the nitril of 
formic acid, and therefore, in the presence of alkalis or adds, it 
easily passes into the latter compound by absorption of water : 

HCN + 2 HjO + HCl = HCO.OH + NH.Cl. 

(7) Formic acid is likewise produced when chloroform is 
heated with caustic potash : 

CHCI3 + 4 KOH = 3 KCl + CHKO, + 2 H,0. 

184 Preparation of Anhydrous Formic Acid, In order to 
obtain pure anhydrous formic acid, the lead salt is prepared from 
the dilute add, and this, when completely dried, is brought into 
a wide glass tube or retort and dry sulphuretted hydrogen 
passed over it. The lead salt is then gently heated just 
to the point at which the acid distils over, inasmuch as at 
higher temperatures disagreeably smelling sulphur products aro 
formed.^ Amongst these a body crystallizing in colourless needles 
is obtained, the exact naturo of which has not yet been properly 
ascertained.^ The distillate thus prepared usually contains some 

• 

^ Kolbe and Schmidt, Ann, Oum, Phcvrm. cxix. 251. 
« Maly, PhU. Mag. [4], xxx. 860. 

* Lotw., Bet, DeuUch Chan. Oes. xiii. 824. 

* Brodie, Proe, JUfy. Soc, xzi. 245. 
' lieb^. Ann. Pkarm, xvii. C9. 

* Wdhler, Ann. Chnju Pkarm. xci. 125 ; Limprecht, Ibid, xcvil 861 ; Hurst, 
Joum. Chem. Soc. zv. 278. 



PROPERTIES OF FORMIC ACID. 273 



sulphuretted hydrogen, and this can be best got rid of by recti- 
fication over powdered lead formate (Landolt). Concentrated 
formic acid may also be obtained by distilling the anhydrous 
sodium salt with anhvdrous oxalic acid/ 

A strong acid, containing 77*5 per cent., may be obtained by 
simply distilling the dilute acid obtained from crystallized oxalic 
acid, a weaker acid passing over first. If anhydrous oxalic acid 
bo dissolved in this warmed acid, it takes up the water, and then, 
when the cold liquid poured oflf from the crystals which are 
separated out is distilled, an almost anhydrous acid is obtained, 
from which, as well as from the distillate obtained by the other 
methods, pure formic acid can be obtained by cooling, the 
aqueous liquid being poured off from the crystals of formic acid 
which are deposited (Lorin). 

185 Properties. — Formic acid is a colourless, slightly fuming 
liquid, possessing a penetrating acid smell, and acting so power- 
fully on the skin that one or two drops produce extreme pain and 
swelling, leaving a white blister, which afterwards forms a painful 
wound. The dilute acid has a peculiar acrid smell, and a purely 
acid taste (Liebig). The anhydrous acid boils at 99°'9, and at 
20* has a specific gravity of 1*2211.^ The vajDour density at 
lir-5 is 2-38; at 1G0^ 1-81; and at 214°, 1-62.8 At a low 
temperature formic acid solidifies to a mass of crystals which 
melt at S'^C* 

Mere traces of water lower the melting-point considerably, 
whilst, on the other hand, the boiling-point is raised by tlie 
presence of water. According to Liebig, the hydrate CHgOg + HgO 
boils constantly at 106^ This compound has been termed 
orthoformic acid, CH(0H)3, inasmuch as corresponding ethers 
such as ethyl orthoformate, CH(OC2H5)3, are known, this latter 
body being obtained by the action of sodium ethylate, CgH^ONa, 
on chloroform. Roscoe ^ has, however, shown that this hydrate 
does not exist, and that a mixture of formic acid and water behaves 
like the various other aciueous acids. On repeated distillation 
under the ordinary pressure, a final product is always obtained, 
containing 77 per cent, of formic acid, and boiling constantly at 
107*'l, whether a dilute or concentrated acid be employed. That 



* Lorin, Bull, Soc. Chim. [2], xxv. 519. 

* LoDdolt, Pogg. Ann. cxvii. 3C2 ; ami Aim. Chem. Pharm. Sujfjil. vi. 170. 
' Petersen and Ekstrand, Ber, Dcutsch, Cfipm, (k*. xiii. 11^4. 

* Berthelot, Bull. Soc. Chivu [2], xxii. 440. 

* Joum, Chcm. Soc, xv. 270. 

VOL. UL T 



27-J 



a mixture of pota*. 
pnxJucc'd : * 

"^^ (OH ^ 

(}i) In a siniil I 
solution of carl' 
amalgam.* 

(4) If carbon •! 
at 100'', ferrous 
iron, carbon <li«».\ 

(5) A small < 
direct union of 
of the silent <•. 
be passctl tin 
tube, small •:* 
carbon monox 
exhibiting tli 

00 Hj-chv 
formic acid, 
easily jiassi'- 

IK 

(7) For: 
heated vvi» 



184 / 
obtain )• 
the dilir 
a wid«' 
passed 
to th»- 
highei 
foniH 
is olit 

ascci'f 

' K 
M 

• r 

* I: 

T 
( 



- - v' ATI 

-..-:• ml 

-* -.:.:. is 

. -•• 'y]itn 

• ".rriijir, 

J :«LVnt3 

f txj'laiijs 



* ^1 

• •• 'l ,• 



• 

i.rioulty in 

> . :. •-♦■.•lihi:, 

'.' -> ' • Ik' n.'- 

. :..'. M- .sahs 

•..:^r. It is 
.■•.vstallizabK- 

m 

.:*• rradilv in 

>^ ^> .1 o»ol and 

. '.tv r aiid for- 

., .\^::;jMsition 

. \.%v* raii«»n ot 
r^- r!i.>iid»i«' 



•- \ 1 



THE FORMATEa 276 



cxystals, which dissolve in from eight to ten parts of cold and in 
not much less hot water, and are insoluble in alcohol. 

Barium Formate, (CH.O^^Sk, forms transparent rhombic 
prisms, which are soluble in four parts of water, but do not 
dissolve in alcohol. 

Lead FomuUe, (CH02)j)Pb, a very characteristic salt of formic 
acid, crystallizes in glistening white prisms, which are isomor- 
phous with the barium salt. It possesses a sweet styptic taste, 
dissolves in sixty-three parts of cold and 5*5 parts of boil- 
ing water, but, like the foregoing salt, is insoluble in alcohoL 
When the solution is warmed with oxide of lead, the following 
basic salts are obtained : 

O I ?Jf^l^* O I Pl»C!HO, (J f PbCHO, 

t PbCHO, j pjj \^^ 

^ { PbCHO. ^ { 



°{ 



Pb 

PbCHOy 



These are soluble in water, exhibit an alkaline reaction, and 
crystallize in needles.* 

Copper Formate, (CKO^JOn + 4H2O, crystallizes in light-bine 
monoclinic prisms, and yields with formic acid the compound 
(CiaO^fiM + 2CH2O2 + 3H2O, which also crystallizes in the 
monoclinic system.^ 

Silver Formate, CHOjAg. Silver oxide or silver carbonate 
dissolves in cold formic acid, although silver is reduced when the 
acid is hot. On evaporating in a vacuum, small six-sided 
rhombohedral tables are obtained, which are also deposited 
when a concentrated solution of silver nitrate is mixed with one 
of sodium formate. From concentrated solutions it separates 
out as a curdy precipitate. It blackens easily even in the dark, 
and especially when moist, and decomposes on heating according 
to the equation : 

2 CHOjjAg = 2 Ag + CH,0, + CO,. 

Mercuric Formate, (CH02)2Hg, is obtained by dissolving mer- 
curic oxide in cold dilute formic acid, and remains, when the 
solution is evaporated in a vacuum at 0^ in the form of a white 
granular crystalline mass easily soluble in water. 

^ Barfoed, Joum. Pr. Chem, CYiii. 1. 
3 V. llauer, Wien, Akad, Ber, zliii. 548 




276 THE FOR^nrL GROUP. 



Mercurom Formate, (CHOJjHgj, is formed when the solution 
of the foregoing salt is gently warmed : 

2 (CH02)2Hg = (CH02)2Hg2 + CH^O, + CO^ 

It crystallizes in microscopic four-sided or six-sided tables, and 
dissolves at IT'' in 520 parts of water. Like the silver salt, it 
blackoDS even in the dark, and, when heated with water, decom- 
poses into mercury, carbon dioxide, and formic acid. The dry 
salt deflagrates slightly when it is quickly heated, and decomposes 
on percussion. 

187 Methyl Formate, CH02(CH3). This ethereal salt was first 
prepared by Dumas and Peligot by distilling methyl sulphate 
with sodium formate. Vol hard ^ recommends the following 
method : 130 parts of hydrochloric acid recently saturated with 
wood spirit are added gradually to 100 parts of calcium formate. 
As soon as the somewhat violent reaction is over, the distillate 
found in the cooled receiver is poured back into the retort, the 
whole warmed for a short time and then distilled on a water- 
bath. The liquid which passes over is washed with a saturated 
solution of common salt containing a little carbonate of soda, 
and then dried over a large quantity of finely powdered anhy- 
drous calcium chloride, with which substance the ethereal salt 
combines on slightly warming, forming an apparently dry mass. 
This is then again distilled from a water-bath, and the first 
portions, which contain chlorine, are collected apart. According 
to Bardy and Bordet, ^ it is better to use a mixture of methyl 
alcohol and aqueous hydrochloric acid, and to act with this upon 
dry sodium formate. Methyl formate is also readily obtained by 
digesting methyl alcohol with concentrated formic acid,^ as well 
as by acting upon hydrocyanic acid with wood spirit saturated 
with hydrochloric acid (Volhard) : 

HCN + HO.CH3 + HCl 4- HgO = NH.Cl + HCO.OCH3. 

Methyl formate is a mobile liquid possessing a peculiar smell, 
boiling at 30°'4 under a pressure of 712 mm. and having a 
specific gravity at 0° of 0-9928 (Volhanl), and a vapour density 
of 2084 (Dumas and Peligot). If its Tapour be passed through 
a red-hot tube, it decomposes almost completely into carbon 
monoxide and methyl alcohol : 

HCO.OCH3 - CO + HO.CHj. 

' Licbi(i*n Ann. clxxvi. 12S. ' RuH. Sor. f*h'm, xxxi. 631. 

' Kracmer and Grodzki, JJrr. /kuf^tch, Chtm. Ucs, ix. 1928. 



FOBMAMIDE. 277 



Acted upon by chlorine, it yields as the last product jMreUor- 
methyl formate, CICO.OCI3, a powerfiiUy smelling liquid, boiling 
at 180'', which when heated to 320"* splits up by intermolecular 
interchange into two molecules of carbonyl chloride, COCl^ 

Methylorthqformatc, GTiI(pGJI^^, is prepared by the action of 
chloroform on a solution of sodium methylate, and is a colour- 
less, mobile liquid, with a pleasant odour, and boiling at 101^ 
to 102^^ Substitution-'products of fonnic acid are unknown, as 
the acid is decomposed by chlorine : 

CH2O2 + CI2 = 2HC1 + COy 

The chlorocarbonic ethers, however, obtained by the action of 
carbonyl chloiide on the alcohols, may be regarded as ethers 
of monochlorformic acid. Of these the methyl compound, 
CClOgCCHj), has been already described. It is also formed by 
the action of perchlormethylformate on wood spirit. The formyl 
chloride, corresponding to formic acid, is likewise unknovm, for 
by the action of phosphorus pentachloride on formic acid only 
carbon monoxide and hydrochloric acid are obtained. The 
anhydride is consequently unknown, nor has thioformic add 
been prepared. 

Formamide, N(C0H)H2, was discovered by Hofmann * in 1863. 
He obtained it by heating ethyl formate, saturated with 
ammonia, for two days at 100^ in sealed tubes : 

Behrend ' prepared it by heating two parts of ammonium formate 
with one of urea to 140^ as long as ammonium carbonate 
escaped. The ammonium salt thus decomposes into formamide 
and water ; the latter, which would retard the reaction, at onoe 
combines with the urea to form ammonium carbonate, and thus 
becomes inactive. Lorin^ has found that it can be readily 
obtained through dry distillation of ammonium formate, and 
also occurs as one of the products of the distillation of am- 
monium oxalate. It is a colourless liquid, soluble in water and 
alcohol, but insoluble in pure ether, and boiling at 192* to 196**, 
with partial decomposition. This takes place in two directions, 

^ Ber, Detitxh Ckem, Oes. xii. 117. ^ Joum. Okem, 

* Ann, Chem, Pharm, cxxviii. 383. ^ Compi* Bend, 




278 THE FORMYL GROUP. 



one part decomposing into water and formionitiil (hydrocyanic 

acid): 

COH 

H = H.0 + NCH, 



.1 



and another part splitting up into ammonia and carbonic oxide. 
Under diminished pressure it volatilizes without decomposition 
at 140' to 150*. Phosphorus pentoxide withdraws water from 
this compound, forming hydrocyanic acid, and concentrated 
caustic potash decomposes it in the cold with formation of 
potassium formate and ammonia. 

(COH 
Methyl Formamide, N < CH3 This body, metameric with 

(H. 

acetamide, is obtained by evaporating an aqueous solution of 
methyl ammonium formate to a syrupy consistency and dis- 
tilling the residue. On the addition of potash to the distillate 
the amide separates out, and it is purified by rectification. It 
is a thick inodorous liquid, having a specific gravity of 1011, 
and boils under a pressure of 740 mm. at 190^ It is soluble 
in water and alcohol, but insoluble in ether. It is inflammable, 
burning with a purple-bordered flame. Phosphorus pentoxide 
acts violently upon it, decomposing it into carbon monoxide 
and methylamine, and at the same time some hydrocyanic acid 
is formed.' 

lieactions of Fomiic Acid and the Formates. Some of the 
more important reactions by which formic acid and its salts 
can be recognised have already been given. 

On heating with concentrated sulphuric acid, pure carbon 
monoxide is evolved without any blackening, this gas burning, 
when ignited, with its characteristic pale blue flame. Ferric 
chloride colours neutral solutions of a formate a red brown with 
production of ferric formate. This reaction is, however, ex- 
hibits! by acetic acid and the sulphites, but formic acid can 
readily be distinguished from these, inasmuch as its solution, 
when warmed with silver solution, evolves carbon dioxide, finely 
divided silver being at the same time precipitated and deposited 
in a mirror on the tube. 

^ Liiincrnaiin, Bcr, U'i^n Akad, Ix. 44. 



7f . ■ • 



;our. 



KS48 by FranklancI and 

nil on moist acctonitril 

upon as the free radic«al 

>•' showed that this same 

■ sis of acetic acid (methyl 

i.se obtained it by heating 

sure. When the truth of 

V recoimised bv chemists, 

d, and for some time tliis 

It was believed to diflfor 

;ias had been obtained by 

with zinc and water. The 

was, however, afterwards 

ily to agree exactly in their 

;il properties, inasmucli as 

iiose various processes all 

with chlorine as the first 
I 

i\'nsylvanian petroleum^ as 
"Ived from the oil wells.^ 
■'1 in many ways. Of these 
as yield it easily and in a 
a stated that Kolbe obtained 
111 acetate. The ap[)aratus 
ihes as follows : ^ A small 

« JbuL n. ir,7. 

ti'lM of Ethyl," Chi-.ia. fiitc, Jtmrn, 



Siidtler, AmtTi 




1707 



TOE ETHYL GEOCP. 



glass cvltnd«^r t^^.Fig. 6S. open at both eoild, is finulv bstened by 
& piece of shc«t c&ontt-houc to tb€ top of a. small porous cell (a) 
of the same diameter. The cylinder is ' 
, closed a: the top with a well-fittii^ cork, 

to which two thin glass tubes are fixed ; 
down one of these a stout fdatinum wire 
passies. to the lower end of which is attached 
a piece of platinum foil, bent as shown by 
the doited lines, and serving as the electrode. 
The second tube (0 is connected with a gas- 
ilelivery tube. The whole apjMratus stands 
ill a wide glass cylinder open at the top (rr. 
Fig. (>!•', and is sumHuujed by a cylindrical 
pittv of sheet copper placed outside the porous 
Ki>t. es. i.vll, anil sei^'ing as the other electrode. Both 

vessels aiv filled to the same height with 
a solution of a«.x>tate of {totash ; the liquid is poured into the 
inner one by means of the tube until the columns of liquid 
inside and outside stand about two inches above the top of the 





huiid of riiiiiitcliiiiK'. 'I'lio MiliiMi'ii of |K'tiuuiiini acetate must 
1m) tolerably i-i.iirriitnitj-il nml U'" fi""i chlorine. If the nega- 
tive jiolc of n luiHmy 'if f'ltn Ifniioeii's 'lemunts be connected 
with lluf copiK-r I'ImtriMir . ni»l (liu |Krtitive with the platinum 



ETHANE OR ETHYL HYDRIDE. 281 



cylinder, pure hydrogen is first evolved, and afterwards a mix- 
ture of carbon dioxide and ethane, and this gaseous mixture 
passes through the bulb-tubes (/) filled with potash solution. 
The ethane is still mixed with another gas possessing a peculiar 
smell, whose nature has not yet been properly ascertained. To 
separate this gas, the ethane is next passed through the bulb- 
tube (g) containing fuming sulphuric acid. The gas is after- 
wards washed by passing through the bulbs {h) containing 
caustic potash, and again dried by passing through the bulb (i) 
containing strong sulphuric acid. The gas thus purified and 
consisting of a mixture of 66 volumes of hydrogen with 28 8 
volumes of ethane is next passed into the smaU mercury gas- 
holder (k), which is so arranged that by gradually raising the 
inner bell-jar any excess of pressure in the apparatus may be 
avoided. 

Pure ethane can also be obtained by allowing zinc ethyl to 
pass drop by drop into water. The reaction is very violent, and 
the liquid must be well cooled to begin with (Frankland). 

It is likewise easily formed by the action of sulphuric acid 
on mercuric ethyl, according to the following reaction : 

2 Hg(C,Hs), + HjSO, = 2 C^ + (CjH5Hg)^0,. 

In order to purify the gas thus obtained from traces of mercuric 
ethyl which evaporates with it, it is led through fuming 
sulphuric acid and then through water (Schorlemmer). 

According to ScTiutzenberger ^ it is also obtained by the 
action of barium dioxide on acetic anhydride, according to the 
following equation: 

2 cS::CO } O + BaO, = g|» } + g5gg;0 } Ba + 2 CO, 

Darling,^ who endeavoured to prepare it in this way, only suc- 
ceded in obtaining a gaseous mixture containing less than 
one-fifth its volume of ethane, the remainder consisting of 
marsh gas and a small quantity of carbon monoxide. 

189 Properties. — Ethane is a colourless odourless gas condensing 
to a liquid under a pressure of 46 atmospheres. It is a singular 
fact that the vapour-tensions of ethane, CgH^ ethylene, CjH^, 
acetylene, CjHg, stand in the same relation to one another as 
the quantities of hydrogen contained in their molecules do, 
that is as 3:2:1.' 

* Conipt. Reiid. Ixi. 487. » Loc. eit, 

» Cailletet, Compt, Rtnd, Ixxxv. 861. 



282 THE ETHYL GROrP. 



Ethane is easily iuflammable, burning with a faintly luminous 
flame. It is slightly soluble in water, according to Schicken- 
dantz, its absorption-coeflScient is represented by the following 
expression : 

C = 0094556 - 0-0035824 1 + 000006278t'. 

At the ordinary temperature alcohol dissolves about its own 
volume of this gas. 



ETHYL ALCOHOL. 

190 Fermented drinks were known in very early times. Wine 
is mentioned in Homer and in the Old Testament, and the 
Egyptians, Gauls, and Germans, and other ancient nations, 
understood the art of brewing beer from malted grain, whilst 
the northern peoples prepared mead from honey. The exist- 
ence of alcohol in all such substances was first recognised after 
the Alexandrians had perfected the extremely rough methods 
of distillation which had up to their times been employed. 

Distillation. — This appears to be a fitting place to give some 
account of the history of distillation,^ a process constantly 
employed by chemists. Aristotle refers to the fact that sea- 
water can be rendered fit for drinking by evaporation, but he 
does not explain by what means the vapour is condensed. Still 
there can be little doubt that this was effected by means of the 
cover of the vessel, for Alexander of Aphrodisias writing in the 
third century describes an apparatus of this kind. 

Both Dioscoridcs and Pliny mention that an oil can be obtained 
from rosin by heating it in a vessel in the upper part of which 
some wool is placed for the condensation of the oil. The first- 
named author also mentions that quicksilver is obtained by 
heating cinnabar in an earthenware pot together with iron, a 
cover termed a/i/8tf being placed over the pot. An important 
improvement in distillation was made by the Alexandrians, as 
they employed two vessels, one for evaporating the liquid and 
the other for condensing the vapour. The forms of apparatus 
which they employed are shown in Figs. 70 and 71. In prin- 
ciple they are similar to those used at the present-day. 

The two parts of the distilling apparatus were, first the 

» Kopp, OfAch. Her Chemir, ii. 26, iv. 273; BtUrajt, i. 217. 



HISTORY OF DISTILLATION. 



283 



body, or still, and secondly the head, from which either 
one or several tubes passed to the receiver. The Arabians 
termed the head or cover alavibic or alembic, and this word 
was subsequently employed to designate the whole apparatus.^ 
The invention of the retort, a long-necked flask in which the 
neck was bent back (Betorta, ampvlla), we also owe to the 
Arabians. 

Basil Valentine was the first to mention a tubulated retort, 
and he illustrates its form by a figure. The cooling-vessel 
and condensing-worm wete also first described by Valentine. 
Fig. 72 represents a form of distilling apparatus from a German 
edition of Geber's works dated 1710. 




Fio. 70. 



Fio. 71. 



Other improvements in the arrangements for distillation will 
be described under the manufacture of alcohol. 

igi The discovery of a combustible spirit of wine soon led 
to attempts to obtain it of a greater strength than was found 
possible by repeated distillation. Raymond Lully described 
this method, and also noticed that a still stronger spirit can be 
obtained by rectification over dry carbonate of potash, whilst 
Basil Valentine states, more precisely than Lully, the method 
to be adopted for obtaining strong spirit by means of calcined 
tartar and subsequent distillation. Thus in the Offenharung 
der Handgriffe, &c., p. 487, he says: "Having now prepared 

* See E. "Wiedemann, Zur Cliemie der Araber, Deuhch, Morgenldnd. Oes. 1878. 



284 THE ETHYL GROUP. 

this aqua vitm by distillation and rectification (take care that 
thou comest not near with a light during the process, and doest 
thyself damage), place in a still to every quart of this prepared 
aqua vUm a quarter of a pound of well calcined sal tartari. 
Adapt to this a good sized alembic (headj, and distil in a 
RM. (water-bath)." 

Robert Boyle likewise specially describes the means necessary 
ba obtaining " depbl^^ed spirit of wine " from ordinary spirit. 
He recommends ' for this purpose not only the use of " white 
calx of tartar," but also of quick-lime. He atatos that on careful 
distillation " the phlegmatic part of the spirit of wine is soaked 
up by the alcalizate salt, and the inflammable part is freed from 




it ; " adding, " therefore, this alcohol of wine we peculiarly call 
the alcalizato spirit of wine." Basil Valentine also mentioos the 
use of freshly-burnt lime, but this process was used by him 
rather with the view of making the lime stronger than of 
preparing a more active spirit 

Bectification at a low temperature was, however, a much 
more common mode of dehydration than the use of potashes 
or lime, tn order to condense the vapours completely they 
were passed through long cooling tubes, often curved and bent 
in on extraordinary fashion. Not unfrequently the head was 
■ Doj'lc, Oftm. i. 333. 



ALCOHOL : HISTORY OF ITS PREPARATIOX. 285 

raised high above the body of the still in order to retard the 
passing over of aqueous vapours. Indeed Michael Savonarola, 
in his treatise, De Arte Confidendi aquam Vitos Simplicem et 
compositam (1532), relates that a friend of his had built a still 
having its body in the cellar and its head under the roof of 
the house. 

zga Alcohol was formerly designated by very different and often 
by most fanciful names. Thus, for instance, Marcus Grsecus, 
who is said to have lived in the eighth century, calls it aqua 
aniens, and the Latin translators of Geber's writings term it 
aqua vitas; and in addition to these names, of which the 
latter has come into general use, we also find aqua vitis (beet- 
root water), spiritus vivus, mercurius vegetahUis, and a number of 
other pharmaceutical names. Moreover, as it is used as one of 
the most important medicines, Raymond Lully terms it con- 
solatio ultiriia corporis humani. The name of spirit of wine 
(spiritus vini) first occurs in Basil Valentine, and the name 
alcohol was first used in the sixteenth century. It has 
already been stated in the second volume (Part II., p. 301) that 
the word was first employed for designating the native sulphide 
of antimony (speissglass), and was afterwards made use of to 
denote any finely divided, but especially metallic, powder. 

It is difficult to say how it came to be applied to spirits of 
wine. Libavius, in his Alchf/mia, published in 1594, says: 
** Quando vini spiritus rectificatur per suum salem (that is, 
carbonate of potash prepared with cream of tartar), sou potius 
exasperatur, nominant vini alcool, vel vinum alcalisatum." 
In Johnson's Lexicon Chymicum, published in 1657, pages 12 
and 13, we find the following explanation : *' Alcohol, est 
antimonium sive stibium." And again, " Alcohol, vini, quando 
ominis superfluistas vini k vino separatur, ita ut accensum 
ardeat, donee totum consumatur, nihilque faecum aut phlegmatis 
in fundo remaneat." 

The extract from Libavius, and that already cited from 
Boyle, appear to point to the fact that strong alcohol was 
formerly termed vinum alcalisatum (that is, wine strength- 
ened by means of alkali), and that, perhaps by some misun- 
derstanding, this came to be written innum alcoholisatum, from 
which afterwards it became alcolcol vini. 

Another derivation which appears to bo about as probable as 
the one just stated, is that the word alcohol, after its general 
employment to signify a very finely divided body, was made use 



28G THE ETHYL GROUP. 



of to designate spirits of wine^ because this was wine freed from 
all grosser particles. 

193 Manvfadure of Alcohol, — The manufacture of alcohol on 
a large scale is carried on by distillers, and forms an important 
branch of industry, the gradual development of which haa 
exerted no inconsiderable influence upon the history of civili- 
zation. Of all chemical compounds, alcohol is the one which 
has most materially affected human progress. Alcohol was 
originally obtained, as has been remarked, by the distillation 
of wine, and the fact that it was contained in beer naturally 
led to its preparation by the action of yeast upon malted grain. 
Up to the end of the fifteenth century, alcohol was used as 
a medicine, its taste being rendered agreeable by admixture 
of sugar, herbs, aromatic berries and essential oils, and so 
it gradually came into general demand, inasmuch as it was 
believed that, if daily taken in small doses, it had the effect 
of preserving youth and health, and thus it was that brandy 
soon became a recognised drink throughout Europe. 

As soon as alcohol began to be used in the arts and manu- 
factures, means were taken to find a cheaper method of preparing 
it than from malted grain, and for this purpose not only were 
potatoes and beet-root employed, but also cane-sugar, beet-root 
sugar, and molasses. The marcs, or residues of the wine presses, 
and sweet fruits, such as cherries, plums, all of which contain 
both sugar anil starch, are also used for the preparation of spirit 
of wine, whilst, in the East, rice and sorghum are the chief 
sources, and in America, spirit is obtained from potatoes and 
Indian corn. The materials which are thus used in the pre- 
paration of spirit of wine may, therefore, be arranged in three 
groups. In the first of these are classed the grape and other 
sweet fruits which contain fermentable sugar, or glucose, 
C^jHjjO^j. The juice of such fruit enters into fermentation 
spontaneously on exposure to air, under the action of a ferment 
contained in the nitrogenous constituents of the juice, the sugar 
thus being converted into alcohol. Further remarks on this 
subject will be found in the chapter on Fermentation. 

The second group includes substances which contain common 
or cane-sugar, C^^^ifiiv ^^^ order to bring this into a state of 
fermentation, the ferment, yeast, must be added to a dilute 
solution, the first step in the process being the formation of 
fermentable sugar by assumption of the elements of water. 

To the third class bcl<»ng the variuusi kinds of grain, ]><>tatoes, 



THE MANUFACTURE OF ALCOHOL. 287 



and other substances containing starch, (CgHi^,05)n. This sub- 
stance is insoluble in cold water, but forms a gelatinous mass 
when boiled with water, and can then be converted into fer- 
mentable sugar by the addition of malt or malt extract. This 
contains a peculiar ferment termed diastase, which is also 
formed in the process of malting the grain. Dilute sulphuric 
acid also possesses the power of effecting this* same change, 
converting the starch meal into sugar on boiling with water. 

Grain Spirit is usually prepared from barley, rye, wheat, or 
oats, but maize and rice and other grain are likewise employed 
for the purpose. In general, a mixture of several sorts of grain 
is made use of, inasmuch as it has been shown that when two 
kinds, such as barley and oats or wheat, are used, the yield of 
spirit is larger than when one kind is treated by itself. To 
1 part of malted barley 2 to 3 parts of unmalted grain 
[termed the grist) are usually added, but in some cases the 
proportion of the latter is still larger. The grain is broken up 
tolerably finely, either between ordinary grindstones, or, in the 
case of the softer malted grain, between rollers of a suitable form. 

Mashing, — The crushed grain and malt is next run into the 
mash-tun, where it is mixed, in the proportion of 1 litre to 
1 kilo of malt, with water having a temperature of about 
GO* and carefully stirred so as to avoid the formation of lumps. 
After the first mash has stood for about half an hour, the liquid 
is drawn off, a second supply of water added, and the mash 
warmed by passing in steam until the whole is raised to a 
temperature of about 65°. The tun is then covered for some 
hours and allowed to stand, in order to permit the complete 
conversion of the starch of the grain into sugar by means of 
the soluble diastase of the malt. The cold wort is then brought 
into a fermenting vat and yeast added, in the proportion of 2y 
to 3 kilos of dry brewer's yeast for every 100 kilos of grain. 
The fermentation begins after a few hours, and should last four 
or five days. The attenuated wort, the specific gravity of which 
ought to be nearly equal to that of pure water, is then sub- 
mitted to distillation with as little delay as possible ; and at 
the conclusion of the operations 100 kilos of grain should yield 
about 28 litres of pure alcohol. 

Spirit of wine is largely obtained from potatoes, especially 
in Germany. The roots are first softened with steam, then 
rasped on a machine with warm water. Malt is then added to 
convert the potato-starch into sugar, and the processes of 



2d8 THE ETHYL GBOUP. 



mimhing, infusion, and fennentation carried on as in the 
mannfactore of grain spirit. 

Beet-root is worked up in different ways. The root is ruhhed 
down and the juice pressed out ; or the root is cut into slices 
and the sugar washed out hy hot water, or hy the residue of a 
distillation of a former operation. To the liquid, yeast is added, 
and the liquor allowed to ferment Alcohol is also manu£Eu> 
tured from the molasses ohtained in the cane and beet-root 
sugar industries. The syrup, after sufficient dilution with 
water, is allowed to ferment, and on distillation a spirit, known 
as rum, is obtained. 

Z94 Lavoisier, and at a later date Gay-Lussac, showed that 
the alcoholic fermentation of sugar proceeds according to the 
following equation : 

CeH^Oe = 2 0,11^0 + 2 CO^ 

Pasteur afterwards found that the whole of the sugar does 
not undergo the above change, but that from 5 to 6 per cent, 
is converted partly into glycerin, CjHgO,, and succinic acid, 
C^H^O^ and partly used up for developing the growth of the 
ferment In addition to this, and under conditions which are 
not yet properly understood, the alcoholic fermentation gives 
rise to higher homologues of common alcohol, fatty acids, and 
ethereal salts, which impart to the various spirituous liquors, as 
well as to plain spirit, its peculiar smell. These bodies, all 
of which boil higher than common alcohol, are classed together 
under the name of fusel-oil, though sometimes the name is 
applied uiiiiply to those which impa4 to the spirit a disagreeable 
odour. 

195 The first crude forms of distillating apparatus have already 
been described. As soon as spirit was required in larger quan- 
tity these stills were increased in size, and made of copper and 
other metals instead of pottery. A simple apparatus which was 
formerly in general use and is still employed on the small scale 
for the manufacture of the more valuable kinds of brandy 
(from the old German Brandewein), is shown in Fig. 73. The 
wort is heated on the body of the still, and the vapour is con- 
densed in the worm. 

The distillate consists of a dilute alcohol termed "low 
wines " or " singlings,'* and from this, by a second distillation 
or "doubling," a stronger alcoholic distillate is obtained. 
This process is carried on until the spirit begins to acquire 



RECriFICATlON OF SPIRIT ^89 

a (lisagreeable taste and smell, and to tliis the name of 
"faints" is given. By repetition of this operation, strong or 
rectified spirit is made, and at last a highly rectified spirit, con- 
taining 80 per cent, or more of alcohol, is obtained. The older 
operations for separating the spirit from tJie water are tedious 
and costly, and hence a simpler and cheaper method for efiTecting 
this object became a desideratum. The first apparatus of this 
kind was iovented by Adam, in France, and introduced into 
industry by Bernard.' This original apparatus waa soon im- 
proved, and has now been brought to a high degree of perfection. 
The stills employed at the present day consist essentially of 




Fro. 73. 



two parts, (1) the analyzer, and (2) the rectifier. The action of 
the first depends upon the fact that when mixtures of the 
vapours of alcohol and water arc cooled down by suitable 
arrangements, the condensed liquid is separated into two parts, 
one containing a large quantity, and the other a small quantity, 
of alcohol. This principle is made use of on the small scale in 
laboratories in the process of fractional distillation, when Wurtz's 
distillation -bulbs are employed (see p. 150). In the second 
part of the apparatus, the vapours are condensed in a rectifier, but 
none of the liquid is allowed to run back, as in the first part, 
the whole being heated by a current of steam to the boiling- 
point of the hquid, when vapour richer in alcohol is given off. 
Thi.s is condensed in a second vessel, again brought to the 
' am. Ann. xxiu. 129, 
VOL. III. U 



2ao 



THE ETHYL GROUP. 



boiling-pomt by action of steam, and condensed in a third vessel 
ID the fonn of stron*,' alcohol, and thb process repeated. This 
principle is likewise applied on the small scale for fractional 
distillatioD in the laboratory'. 




ig6 The nppanitus uacd for rectifying is constructed in very 
different ways. Of these various forms we shall first describe 
the Iarfj;e apparatux of Pislorius with direct heating, formerly 
iiHirh iisoil in flonnany, as it serves as the point of de- 
(Mirture fur almost all tin- oilier forms of stills and rectifiers 
now in use. At tin- ivtinnienconiciit of the i>perntiou the first 



THE RECTIFICATION OF SPIRIT. 291 

charge of wort is allowed to enter by the pipe {h/) (Fig. 74), 
passing first into the heater (c), thence by the pipe (y) into 
the first boiler (b), and from this into the second boiler 
(a). The second charge is then brought into (b), the third 
remaining in the heater (c). The wort in boiler (a) is 
now heated to the boiling-point, the liquid being constantly 
stirred with the chain (/) to prevent it boiling over. The 
vapours from this pass through the tube (ff) into boiler (b), 
which is warmed by the waste heat from the fire (g), and the 
contents are soon raised to the boiling-point The vapours 
here given off pass by the tube (f) in the head of the still into 
the rectifying vessel (c). In this vessel a considerable portion 
of the water or weak spirit is condensed, flowing down to the 
lower portion, where it coUeets, and is from time to time allowed 
to enter the boiler (b). The vapour of the strong spirit passes 
through the tubes (vv') into the condenser (d), where again 
weaker spirit runs back, and the uncondensed vapour passes into 
a second and third condenser (not shown in the drawing), until 
at last it comes to the tube (d"), whence it passes into a large 
condensing worm, placed in a tub of cold water, from the end 
of which it runs into the receiver. 

Fig. 75 represents a Pistorius still, worked, as is now usual, by 
steam instead of an open fire. The boilers (a) and (b) are placed 
vertically above one another, (c) is the rectifier and (d) the con- 
denser. The direction taken by the vapour is indicated by arrows. 

197 When very large quantities of spirit have to be distilled, 
and especially in this country, where, owing to Excise regula- 
tions, large distilleries are the rule and grain-spirit is alone 
manufactured, an arrangement known as " CoflFey's still " is em- 
ployed. It consists of two columns (a) and (b) (Fig. 76) placed 
side by side. These are made of wood 5 or 6 inches thick, and 
are lined with copper. The "analyzer" (a) is divided into 12 
small compartments by 11 horizontal plates of copper (a) per- 
forated with numerous holes and furnished with valves opening 
upwards. Dropping pipes (6 b) are also attached to each plate, 
the upper end of the pipe being an inch or two above the 
plate, and the lower end dipping into a shallow pan (c) placed 
on the lower plate. 

The second column or " rectifier '* (b) receives the spirituous 
vapours passing from the column (a) through the pipe (ff). 
This column is also divided into compartments like (a), but 
there are 15 instead of 12. The 10 lower diaphragms (/) are 

U 2 



THE KTHVL GROUP. 




"COFFEVS" STILL. 




294 THE ETHYL GROUP. 



pierced with small holes and furnished with drop-pii)es, whilst 
the upper 5 have only one large opening surrounded by a ring 
to prevent the finished spirit from returning. 

Between each of these compartments passes a bend of a long 
zigzag pipe (n n n"), one end of which is attached to the pump (w), 
whilst the other end discharges the contents of the pipe into 
the top of the column (a), as indicated by the arrow. The 
following is the working of the appsuratus. In the first place, 
the fermented liquor or wash is pumped up by the pump (m) 
until the zigzag pipe is filled and the wort flows over the com- 
partments (a a a). Steam is then admitted into the analyzer 
by the pipe {d) and heats the wash, which is deprived of all its 
alcohol by the time it reaches the bottom of the cylinder and 
flows off by (e/) as spent wash. The sti"ong spirituous vapour 
passes through (^) to the rectifier, and at last through the worm 
(c) of the refrigerator into the receiver. 

198 In order to separate completely the spirit of wine from 
the strongly scented fusel-oil, the crude spirit may be filtered 
tlirough freshly ignited and finely divided wood-charcoal, or, its 
vapoiir may be passed through a cylindncal vessel provided with 
a he<a(l, containing a large number of perforated plates upon 
whi(^h coarsely divided charcoal is placed. 

Experience has however shown that the spirit may be freed 
from fusel-oil by bringing it up to a concentration of 90 per 
cent, of alcohol by rectification, as the fusel-oil boils higher than 
alcohol. Hence the simplest means of removing the fusel-oil is 
to concentrate the spirit. Coffey's still answers these require- 
ments, producing a pure neutral spirit up to 68° over proof, and 
free from fusel-oils. In France and Germany, where Coffey's 
still is pot used, a second distillation is carried on in a rectifying 
still. Fig. 77 shows the construction of such a still, much used 
on the continent and known as the French column apparatus. 
It consists of a boiler (a) heated by a steam-pipe ; the vapours 
pass through the rectifier (b), then pass to the condenser (c), and 
tluj highly concentrated spirit condenses in the refrigerator (d), 
whilst the ** phlegma " (or aqueous portion) flows by the tube (e) 
back into the rectifier. 

Various products are obtained in the foregoing process. The 
first portion of the distillate serves to wash out the apparatus ; 
It contains bodies which are much more volatile than alcohol, 
such as aldehyde.^ Next comes the fine spirit, containing from 

' KninitT and Pinnvr, Btr. DeuttcK Chem. Ots, iii. 75. 



THE FRENCH COLUMN APPARATUS. 296 

90 to 95 per cent, of alcohol according to the more or less 
complete manner in which the apparatus works ; and after this 
common spirit, containing 85 to 86 per cent., comes over, and 
lastly the " faints" containing the strong-scented fusel-oil. The 
first and last niDnings are generally mixed together, and either 
sold as common spirit or worked up a^ain by the distiller. 




199 "^^^ preparation of rice-spirit, or shochu, is conducted in 
Japan accordii^ to the following primitive plan. Rice is allowed 
to undei^o a peculiar kind of fermentation : this yields the 
beverage called sak^ (from ki, spirit), containing from 11 to 
15 pet cent, of alcohoi The residue, after pressing out the 
sak4 moistened with some poor qualities of sak^, is then 



Tw TuMh * j itvi!:^ Ji. *. -ah ;B"TTU*=i ■wnn i yni i TMgrf . 

- - r 






""Jc ^OICE. T3ji:3. 'ai3L Mlt- 
• i "iu: awl ~ ■ <i!pC 'SkiL 

jiiii tie itx^ 3 . Tie 



'p^ '^^A.ftiii^ *wr,r 6".nv Vjt r^jiKCe ■■:ii::az3i!i: in. !';ittaii:o 

j»7^ -i-^i *,. ;:ij-,n fj» ia,; ir^tar^L a 11:111 ^aa; h .-'.aaianl 
•■.;fr>'.v,.-.j', v.i.'i '*tt,7i wilir. irii- I.:-.: \ b»:«rr fc-cn:*i s» Jbtt 
•"w"^. -,^ •iv.pf.:-..'i<*. «rwi -,r. i^,c.,L. icii wiiai wora oeased 
m.ff. 9\rfr f^ji* klrr,i.r,i uA iiilpc^irv: SiZLi.' Tbis iaipocuai 
'.t^H^iTituxt »f»ri^>fli r/T;! l.-.f.;* ^-jui-re •^z.-zl «cirni*«i by Ber- 
'i',*;/.' ,'. I <-'.' ■ Tr.U lr.rt*3ijO ■■■»« :ii* Mt step in th* frnthestt 

f'ttstt. iui;f.tj^. '^1, \^ '.>jtair,*»i by direct <~j[LLbioAdon of iu 
t:$tf,'i.'*. xiA 'iiit rliia r-ottiyinad ombines with iusc«iit 
'•/''"*'*■ *'' ^''"> 'rtfiy!«ifc. The aunt cLemift also pr^pand 
>l",K'>i l,y ',(.(« f/jt^.h'/l fr',t»i '.-ool-^aa, an-J riDrt: that time many 
f>t'fj^)*i\' }•*■■•■: \^ntti ;o»rl«; u> fAtry '*ut tliL* reaction on s large 
w*l'-. Tti'/ tiAV: liow';vi;r liith«ru> pTovot unEnutful. an.i will 

*H|ii-f 'yril.fi"v;<i nf tt\'j<iii,\ bavt already been Ji«tribed 

.,, m, 

%bt Ak'iliul '((-(iir« ill iiatrir':, although in small quantities, in 
tin- v('Ki'inlilc V\u'fi\'tM. TliiiB it iH fotiDii Ixjth in the free slate 
ttuA ' <.M,ln(i«-(l t^, furff) r-iltyl Imtyratc aiwl other ethereal salts, in 

' -On «<■■» ('iiini'niii'U iif ( •rUrt, mi-l lljdrofftn,'' Wi/. TVom, 182J. 4tS. 
■ '■ "I, ih. MtiiMil A'lii,!. '.r Miilt-I'ilnr Arid aii'l Alcohol, "mi7. Tmiu. 18S4^ 
• A»*. Ckim. P/igt. (3], xliii 985. 



PREPARATION OF ABSOLUTE ALCOHOL. 297 



the unripe fruit of Heracleum ffiganteum;^ also in those of 
Anthriscus cerefolium and Pastinaca mtiva, which also contains a 
volatile ethyl compound, probably the butyrate.^ Ethyl 
alcohol is also formed in small quantity in the dry distillation of 
organic substances. Thus, for instafice, it occurs in coal-tar* 
and in bone-oil,* as well as in wood-spirit.*^ It also occurs in 
bread, being formed by the fermentation of dough, and not being 
completely removed in the process of baking. According to the 
experiments of Bolas,* new bread, made with yeast, contains on 
an average 0*314 per. cent., whilst in slices of bread a week old 
012 to 13 per cent, of alcohol was found. Ethyl alcohol is 
also said to occur together with acetone, in the urine of diabetic 
patients,^ and, according to B^champ, it is found in small quan- 
tities in several of the animal fluids, and in larger quantities in 
their products of decomposition. 

202 Preparation of Absolute Alcohol. — Although ethyl alcohol 
is a more volatile liquid than water, it cannot be obtained in the 
anhydrous state from an aqueous spirit by fractional distillation. 
In order to prepare anhydrous or absolute alcohol, substances 
must be added which possess a more powerful attraction for 
water than alcohol itself. It has already been stated that 
Raymond LuUy employed potashes in order to strengthen 
alcohol, and the later chemists used the same means. As, for 
this purpose, they employed the air-dried salt which still contains 
water, they were unable thus to obtain anhydrous alcohol, 
which was first prepared by Lowitz in 1796, by the use of 
freshly ignited potashes. In the same year Richter showed that 
fused hydrochlorate of lime (calcium chloride) may be used for 
the same purpose. Caustic lime is however much more effective 
than either of these salts, and this substance too, it seems, was 
used in early times for strengthening spirit. 

In order to prepare absolute alcohol a retort or flask is two- 
thirds filled with freshly burnt lime broken into small lumps, 
and so much spirit is poured on as not quite to cover the solid 
lime. The whole is allowed to stand overnight, and is then 
distilled from a water-bath. The distillate is usually not 

» Gutzeit, Ber, Deutach. Chtrn. Gcs. xii 2016. 

* Gutzeit, Litbigs Ann. clxxvii. 344. 

* O. Witt, Ber. Deutsch. Cfiem. Oes. x. 2227 ; Vincent and Delachanal, 
Comptes RenduSf Ixxxvi. 349. 

* Richard, Bull Soc, Chim. xxxii. 486. 

* Hemilian, Ber, Deutsch. Chan, Oes. viii. 661. 

* CTiem. News, xxviL 271. 

^ Markownikoff, Liehigs Annaieiiy clxxxii. 362. 



298 THE ETHYL GROUP. 



anhydrous, and for this reason the treatment must be repeated, 
or, the whole may be boiled for an hour with a reversed con- 
denser and then the alcohol distilled off. In this last process, 
however, a spirit should be used which does not contain more 
than 5 per cent of water. If a weaker alcohol be employed, the 
distillation over lime must be repeated several times, and indeed, 
if too much water be present, less than half the retort must be 
filled with lime, as otherwise the vessel may burst from the 
expansion and heat caused by the slaking of this substance. 

Anhydrous caustic baryta acts like lime. It is however much 
more costly, but a small quantity added to lime is useful, inas- 
much as it possesses the property of dissolving completely in 
anhydrous alcohol, giving a yellow-coloured solution, and in this 
way the point when the last traces of water disappear may be 
easily recognised.^ 

The absolute alcohol of commerce, obtained from over-proof 
spirit by use of lime, usually contains half a per cent, of water, 
which can be got rid of by treating the alcohol with sodium.^ 
This metal is also employed for separating the last traces of 
water from alcohol prepared by other methods, but in tliis case 
care must be taken not to add as much sodium as is needed to 
convert the whole of the water into caustic soda, otherwise a 
distillate is obtained which is weaker than the original alcohol 
This singular result has been explained by Lieben.* It depends 
upon the fact that caustic soda partially decomposes in contact 
with anhydrous alcohol with formation of sodium ethylate and 
water. If only a small quantity of sodium be dissolved in 
anhydrous alcohol a decomposition takes place between the 
caustic soda and sodium ethylate, and at first a strong, but still 
not absolutely anhydrous, alcohol passes over ; and if this treat- 
ment be repeated, the production of absolute anhydrous alcohol 
may be approached as near as is desired. 

In order to ascertain whether alcohol contains water, it was 
formerly customary to add to the liquid white anhydrous copper 
sulphate, a substance which has also been employed for the 
preparation of absolute alcohol This however is not suitable 
for the latter purpose, although it may be used as a test, as it 
quickly absorbs water from aqueous alcohol, thereby acquiring a 
blue colour.* 

' Mendelejeff, Pogg. Ann, cxxxviii. 246. 
3 Ber. Chem, Industrie, ii. 278. 
' Ann, Chan. Pharm, clviii. 151. 
* Caasoria, Jaum, Ch^tm, Med. 1840. 



PROPERTIES OF ALCOHOL. 290 



Pure anhydrous alcohol does not give any turbidity when 
shaken up with benzene ; ^ it mixes in every proportion with 
carbon disulphide, and the more water it contains, the less 
carbon disulphide does it take tip, the point of saturation 
in this case being rendered evident by a distinct turbidity 
occurring.^ Another very delicate reaction for the presence of 
water in alcohol is a solution of caustic baryta in absolute 
alcohol, which instantly throws down a precipitate of barium 
hydroxide when brought in contact with alcohol containing 
water.* 

203 Properties. — Pure ethyl alcohol has a peculiar pleasant 
smell, and when dehydrated by means of lime, it possesses ac- 
cording to Mendelejeff a somewhat ethereal smell, which however 
after several distillations is said to disappear. When anhydrous 
alcohol is cooled with a mixture of solid carbon dioxide and ether, 
it assumes a thick viscous condition, but even when exposed to 
the still lower temperature obtained by use of liquid nitrous 
oxide, alcohol does not freeze. Alcohol is easily inflammable, 
bummg with a blue non-luminous flame, and depositing soot 
only when burnt with an insufficient supply of oxygen. That 
its vapour mixed with air forms an explosive mixture is a fact 
which was known to Basil Valentine. 

The physical constants of pure and aqueous alcohol have 
been determined with the greatest care by many investigators. 
According to Mendelejeff, absolute alcohol boils under the 
normal pressure at 78°'3, and has the following specific gravity 
compared with water at S'^'O : 

0* 5' 10* 16« 20' 25" 30* 

0-80625 0-80207 079788 0-793G7 0*78945 078522 078096. 

For the purpose of calculating the specific gravity at other 
temperatures, Kopp*s* formula may be employed, in which 
t? at 0^ = 1 : 

V = 1 -h 000104139 1 + 0000007836 t^ + 0000000001768 i\ 

The specific heat, latent heat, and vapour-tension have been 
determined by Regnault.^ The vapour density of alcohol has 
been found by Gay Lussac * to bo 1*6133. 

* Gorgen, Compt. Rend xxx 691. 

* Tuchschmidt and Follenius, Ber, DtuUch. Chem. Oea. iy. 583. 
' Berthelot, Ann. Ckim. Phys. [8], xlvi 180. 

* Pogg. Ann. Ixxii. 1 and 223. 

* Mim, Acad, xxvi .701. « Ann, Chim. [1], xcy. 311. 



330 THE ETHYL GKOCP. 



AbscJute alcohol is a very hjrgroocopic sabstance, quickly 
absorbing water from the air, and hence care most be taken in 
its preparation that only dry air can find its way into the dis- 
tilling apparatus. A pecaliar obeenration was made by Som- 
mering/ namely, that aqneons alcohol contained in a bladder 
and hung up in a warm room loses water by evaporation, 
nearly absolute alcohol remaining behind. This observation 
has been confirmed by other persons.- 

Boyle mentions in his Erperimental History of Cold that 
when strong spirit of urine "drawn off from quick-lime, the 
better to dephlegm it," is mixed with snow^ a freezing-mixture 
is formed ; ' whilst Boerhave in 1732 observed that when spirit 
is mixed with water a rise of temperature occurs ; and Reaumur 
showed, in the following year, that a diminution of volume 
likewise takes place. This contraction is greatest when one 
molecule of alcohol is mixed with three molecules of water 
(Mendelejefl). In order to exhibit this contraction a long glass 
tube is half filled with coloured water, and then strong spirit 
poured carefully on to the surfBu^e until the tube is nearly 
filled and the volume of the two layers indicated. The liquids 
are then mixed by shaking and reversing the tube, and the 
diminution of volume noticed. 

It has already been stated that alcohol and water, in spite 
of the difference in their boiling-points, cannot be completely 
separated by distillation. By means of a suitable fractionating 
apfiamtus, spirit containing 96*5 per cent, of alcohol may, how- 
ever, 1x5 obtained. On the other hand, a residue of almost abso- 
lute alcohol can be procured, as Sommering observed long ago, by 
diHtilling weaker alcohol off first. Thus by using fractionating 
tuW'S containing 33 cups of wire-gauze a spirit containing 98 
per cent, of alcohol yields a distillate containing 97*4 per cent, 
and a ronidue c^nitaining 99 5 per cent, of alcohol. Hence it is 
ch.*ar that a mixture of ninety-seven parts of alcohol and three 
parts of water Ixnls without any alteration in composition.* 

» Iknkachr. Akad. AfUnchni, 1811, 1814, 1820, 1821 

« GwrMn'i HamWook, viii. 260. 

» Boyl<?$ Works, ii. 611. 

« Lc IW, Compt, Rend, bucxviil 912. 



THE PROCESSES OF ALCOHOLOMETRY. 301 



ALCOHOLOMETRY. 

204 The commercial value of alcoholic liquids, except those 
Dvhicb are used as beverages, depends as a rule on the percentage 
of alcohol which they contain. Hence a means by which the 
strength of spirit could be readily ascertained became a matter 
of importance at an early date. Raymond LuUy considered 
alcohol to be pure when a cloth moistened with it took fire 
after the alcohol had burnt oflF, "id est aqua vitae rectificata 
ut ardeat pannus madefactus in ea." 

This method was employed until the introduction of gun- 
powder into Europe, which then was used instead of the cloth. 
This powder-test was in common use during the last century, 
and from this is derived the name of proof -spirit, to which we 
shall have to refer hereafter. Basil Valentine supposed that 
alcohol was pure when it left no water behind after it was 
burnt. This test was long used, and C. J. Geoffrey in 1718 
suggested that the alcohol should be burnt in a graduated 
cylinder in order to compare the volume of the spirit with that 
of the residual phlegm. Bergmann, in 1775, also recommended 
this process. 

The so-called oil-test was likewise in common use. Michael 
Savonarola (p. 285) explains this test by stating that the alcohol 
is poured on to the surface of oil, and notice is taken as to 
whether it remains on the surface or not. In a work published 
by Michael Schrick in 1483 we find, " Oil poured on to the 
surface of brandy falls to the bottom." Even at the beginning 
of the eighteenth century this method was in vogue, being 
believed to be a fairly accurate one. 

Tables representing the contraction which ensues when 
alcohol is mixed with water, as well as the specific gravities of 
these mixtures, were given by R^umur in 1733-5, and also by 
Brisson in the Memoirs of the Paris Academy for 1768. The first 
complete investigation which had for its object the determina- 
tion of the composition of aqueous spirit from the specific gravity 
was, however, made at the suggestion of the English government 
in the year 1790 for Revenue purposes, and Sir Charles Blagden 
was employed to draw up these tables from the results of ex- 
periments made by Gilpin and published in the Philosophical 



302 



THE ETHYL GROUP. 



Transactions for 1794. Gilpin's experiments were so numerous 
and so remarkably accurate that they form, even at the present 
day, the foundation of the processes of alcoholometry, notwith- 
standing the &ct that absolute alcohol was at that time 
unknown. On the discovery of anhydrous alcohol by Lowitz 
and Richter (p. 297), it was shown by Tralles,^ in 1811, that 
Gilpin's normal alcohol contained 10*8 per cent, of water. 
He re-calculated Gilpin's numbers, and the tables thus obtained 
are those which are now in use. Tralles likewise made a series 
of experiments himself for the purpose of controlling Gilpin's 
results. 

In France the standard alcoholometric tables are founded on 
experiments made by Gay-Lussac, the results of which have 
only been recently published.* These agree closely with 
Gilpin's, as Gay-Lussac's normal alcohol contained 10*86 per 
cent, of water. Several other investigations on this subject have 
since been made. Of these we may mention those of Drink- 
water,* Fownes,* and Baumhauer,^ and these very careful re- 
searches entirely confirm the experiments of Gilpin. More 
recently Mendelejeff ® has investigated the matter again, dis- 
cussing the errors of the various experimenters, and he finds that 
in the case of the most accurate of these older measurements the 
specific gravity is determined to within a mean error of 002, 
and the percentiige of alcohol to within an error of '025. In 
his experiments Gilpin employed the Fahrenheit thermometer, 
which then was, as it now is, chiefly used in this country, whilst 
iu Germany the measurements of temperature for alcoholometric 
purposes were made on Reaumur's scale. 

205 The proportion between spirit and water contained in the 
aqueous spirit may be stated either by weight or by volume. 
For scientific purposes the former expression is always used, as 
this is independent of change of temperature. In commerce, 
however, it is usual to employ the proportion by volume, 
inasmuch as spirituous liquors are generally sold by measure. 

Hence it is important to be able to calculate the composi- 
tion by volume from that by weight. For this purpose some 
normal temperature must be chosen, and 60"* Fahr. orlS'^o C. is 
the one adopted in Gilpin and Tralles* determinations, whilst 
( lay-Lussac's experiments were made at l^C 



* Gilbcrtt Annalcn, xxxviii. 349. 
3 Phil. Mag. [3J. xxxii. 123. 



Poffg. Ann. ex 659. 



• Pi>iiillet. M^m. Accul. xxx. 1859. 
** Pharm. Journ. Trans, viu 375. 

* Piiffg Ann. cxxxviii. 103 and 280 



A LCOHOLOMETR Y. . 303 



Let ^=8pec. grav. of the aqueous spirit; a the weight in 
grains of alcohol in 100 parts of the same; F=the volume of 
the alcohol expressed in cbc., then 100 — a = the weight of the 
water, and 

100 = V,S. 

If further s = spec. grav. of alcohol (compared with water at 
the same temperature) then the volumes of alcohol and water 

contained in the spirit are - and 100 — a respectively, and hence 

the percentage vohimes of alcohol and water in the spirit are 

a 100 ^ ^ r 1 u 1 

- • -jjr~ or a. - volumes ot alcohol, 

SYS 

(100 — a) . -- or (100 — a) S volumes of water. 



and 



For the purpose of accurately determining the percentage of 
alcohol in aqueous spirit, its specific gravity must be determined 
by means of a specific gravity bottle. For excise, and general 
purposes, on the other hand, hydrometers are employed, special 
instruments being manufactured in which the percentages of 
alcohol by volume are marked on a scale. Thus for example 
80 per cent. Tralles means that 100 volumes of such a spirit 
measured at 60° F. contain 80 volumes of absolute alcohol 
at the same temperature, but not that, when the latter quantity 
is mixed with 20 volumes of water, an alcohol of the above 
strength is obtained, as a contraction ensues when these liquids 
are mixed. 

In England the normal temperature adopted at the present 
time is 5V F., and the spirit is not valued according to its 
percentage of absolute alcohol, but according to the amount 
of proof spirit it contains. This term is defined by the Act 58 
George III. as " being sucli as shall at a temperature of 5V F. 
weigh exactly j|ths part of an equal measure of distilled 
water." Proof spirit, therefore, contains 49*3 per cent, by weight 
or 57 09 per cent, by volume according to Tralles. Weaker 
spirits are termed underproof, and stronger spirits overproof. 
Thus 25** over proof means that 100 volumes of this spirit 
diluted with water yield 125 volumes of proof spirit, whilst 25° 
under proof means that it contains in 100 volumes seventy-five 
volumes of proof spirit. 

The hydrometer chiefly used in England and sanctioned by the 



THE ETHYL GROUP. 



^cifie Weight (8.) and CapaHly (C.) of Alcohol, at 60° P., relalire to WaU 
0/6O' P. at unify (more exaeUy 12^" R. or ISg" C), at 12-6° R.-lfrS' C. 



', L'ontenta of Alrohol by PeKdUtage I. b, Contenla of Alcohol by Peicsutagc 
ofVolanie. 7. ;] ofWeighr. ■/. 



% 


3. 


C. 


7, [ »■ 


c 





roooo 


1-0000 


50' 0-9343 


1-0703 


1 


0-998S 


1-0016 


51, 0-9323 


1-0726 


2 


0-9070 


1-0030 


62 0-9303 


1-07*9 


3 


O'Bese 


1-0044 


53, 0-9283 


1-0772 


1 


09942 


1-0058 


64, 0-0263 


1-0795 


5 


0-9928 


10073 


65 0-0242 


1-0820 




0-9915 


]-008fl 


66, 0-0221 


1-0845 


7 


0-9902 


1-0099 


57, 0-9200 


1 -08-0 




0-9890 


1-0111 


68 0-9178 


1-0896 


9 


0-9878 


1-0124 


69 0-9150 


1-0922 


10 


0-9866 


1-0138 


60 0-9131 


1-0948 


11 


0-9854 


1-0148 


61 11-9112 


1-0975 


12 


0-9813 


1-0180 


82 0-9090 


l-lOi.l 


13 


0-9832 


1-0171 


63 0-9067 


11029 


U 


0-9821 


1-0182 


01 0-9044 


1-1057 


15 


0-9811 


1-01B3 


65 0-9021 


1-1085 


16 


0-980U 


1-0204 


66; 0-8907 


1-1115 


17 


0-9790 


1-0216 


67, 0-89T3 


1-1145 


18 


0-9780 


1-0225 


68 0-8949 


11175 


19 


0-9770 


1-0235 


69 0-8925 


1-1201 


20 


0-»7«0 


1*0246 


7'i O-8900 


1-1330 


21 


0-9750 


1-0256 


71 0-8876 


1-1368 


22 


0-9740 


1-0267 


72 0-8850 


1-1299 


23 


0-9729 


1 -0279 


73, 0-8825 


1-1332 




0-9719 


r02S9 


74 0-8799 


1-1305 


25 


0-9709 


1-0300 


75 0-8773 


1-1399 


20 


0-9698 


1-0311 


79 0-8747 


1-1433 




0-9688 


1 -0323 


77 0-8720 


1-1468 


2S 


0-9677 


1-0334 


78 0-8603 


1-1504 


29 


0-9fifi6 


1-0345 


79 0-8660 


1-1511 




O-91I55 


1-0357 


80 0-8639 


1-1577 


■31 


0-9043 


1-0370 


81 0-8611 


1-1013 


;32 


0-91131 


1-0383 


82 0-8583 


1-1051 


33 


0-91118 


1-0397 


83 0-8655 


1-1689 


\;u 


0-9605 


r0411 


84 0-8526 


1-1729 


■ 35 


0-9592 


1-0435 


85 0-8406 


11770 


3'! 


0-9579 


1-0440 


86 0-8466 


1-1812 




0-9565 


1 0155 


87 0-8136 


1-1854 


31- 


0-9550 




88 0-8105 


1 1898 


39 
10 


0-9535 
9519 


1-0488 
1-0505 


89 0-8373 

90 0-8339 


1-1943 
1-1992 


41 


0-9503 


1-05-23 


91 0-8300 


1-2040 


43 


0-9487 


1-0541 


92 0-8272 


1-2089 


43 


0-9470 


1-C560 


93 0-82.17 


1-2140 


■41 


0-9452 


10580 


94 0-82O1 


1-3194 


i45 


0-9435 


1-0599 


9B 0-8164 


1-3340 


141 


0-9417 


1-0019 


96 0-8135 


1-3308 


M' 


0-9399 


1-0639 


97 0-8084 


1-2370 


IS 


0-9381 


1-0660 


98 0-8tiir 


1-2136 


|4fl 


0-936-2 
09343 


1-0683 
1-0703 


99 7995 
100 0-7916 


1-2308 
1 ■2.185 



1-0000 
00981 
0-0963 j 
0044 



17 


U-9751 


IN 


0-9739 


19 


0-9727 


20 


0-9714 


21 


0-9702 


22 


0-96911 


?3 


0-9677 


24 


0-9664 


H5 


0-8651 


V6 


0-9837 


V7 


0-9622 


?N 


0-9607 


W 


(1-9592 


30 


0-9577 


31 


0-8560 


32 


0-9644 


33 


0-9520 


34 


0-9508 


36 


0-9490 


30 


0-9472 


37 


0-9453 


;iH 


0-9433 




0-9113 


40 


0-9394 



46 I 0-9309 

47 I 0-9210 
18 0-9337 



53 0-9116 

54 0-9091 

65 0-9072 

66 0-9019 

57 0-9027 

58 0-9001 
69 0-8981 

60 0-8958 

61 0-8935 

62 0-8811 
03 0-8888 
S* 0-8805 



07 0-8795 
68 0-8772 


1-1370, 
1-1400 1 


09 0-8748 


11131 


70 0-8724 


11493 


71; 0-8700 


1-1494 


72 0-8676 


1-15-20 


73 0-8652 


1-1558 


71, 0-8629 


1-1589 


76 0-8605 


1-1621 


70, 0-8681 


1-165* 


77 0-8667 


11686 


78 0-8533 


1-1719 


79 0-8509 


11753 


80 0-8484 


11787 


81 ; 0-8468 


1-1822 


82 0-8435 


1-1856 


83, 0-8409 


r!802 


84 0-8386 


1-1929 


85' 0-8350 


1-1963 


80 0-8333 


1-2000 


87 0-8307 


1-2038 


88 0-8282 


1-207* ; 


80 0-82,W 


1-2112 1 


90 0-8229 


1-2152! 


91' 0-8203 


1-2191 


B2 0-8170 


12231 


93 0-8149 


1-2272 


94 0-8122 


1-281 a 


95 0-809* 


1-23.55 


90 0-8O65 


1-2309 


97 0-8030 


1-244* 


98 0-8006 
09 O-TllTA 


1 -2*91 
1 -2537 



SYKES'S HYDROMETER. 



Excise is known as Sykes's hydrometer, Fig. 79. It is mado of 
metal, and has a four-sided st«m divided into ten equal parts, 
fitting into a brass ball, carrying a small 
conical stem, terminating in a pear-shaped 
loaded bulb. The instrument is also pro- 
vided with nine circular weights numbered 
10, 20, 30, 40, 50, 60, 70, 80, 90, each 
having a slit by which it cau be fixed on 
to the stem. The instrument is so 
adjusted as to float with the zero of the 
scale coincident with the surface of the 
liquid when it is immersed in spirit having 
a specific gravity of 0-82.J at 60°, this being 
the standard alcohol of the Excise. If the 
alcoholometer be placed ia weaker spiiit 
than this, it will need to be weighted, in 
order to bring the zero point to the level 
of the liquid; and the sum of weights, 
together with the number on the scab at 
the level of the spirit, give by reference to 
a table the quantity of proof spirit con- 
tained in the sample. 

As the alteration of volume effected in 
spirit by the variation of a few degrees of 
temperature is considcmble, the reading 
on the hydrometer will only be correct at 
the normal temperature. As. howevcf, 
this point is dlHicuIt to attain, Gilpia 
determined the specific gravity of aqueous 
spirit of diflferent strengths at differeut 
temperatures. All these tables were re- Fio. 79. 

calculated by Tralles, and have since his 

time been corrected by the investigations of Brix, ' von Kupffer,* 
and others.^ 

By the help of these results, a table of corrections is obtained, 
by means of which the true percentage of alcohol contained 
in any spirit at any given temperature may be ascertained 
from its apparent percentage iis read off on the hydrometer 
{sfe Tables pp. 306-7). 

' Das AlhMlnin^tet, he., IV'rliii, 1864. 

• na«Ah. AU-olmhmclrir, B.-llill, 1865. 

• Stc alio Watts'M nictionan-, vol. i. nrticlf " Akoholoinplry." 



THE ETHYL GBOUP. 



IS 
iS 



j t 



hi- 

III I 






S eTw"-;=-c»of«^-»=-«'Vrf'w-^'-o- o.--Mef rfV-o 


" «■«-•=■ cT a «t--oB.-,oVn-n-r--o- <=n,-ef««»>o 




3 , 1 2"«-SS2-rf"-"°-S-«-v«-«-S--2- o---3S«-"-S 


a , ; B-M--^-o-ffl.c't--<-»0'r'nei-».'--o' <=-^-e»'rf-.fV«i- 


' g »-,**.--.-o*o«f<-J.--<D-o*-«««-o' o'-'M-n-VrfB 


, 3 -'««* 2 ;:£"•■ »-"»>«"«''■««'-■= <9"-«« Vvf«- 


'= ' «-.-n'rrn-S'S-s-»-^-5s^'«-S"-3- sr-S'B-52-s- 


' B 1 ' 2 iss's'sn's'* '■'■■'= "-■''""■"''=' 'f-c*'>^"«» 




n ■ .i2''^"2'H'::s"=--""'-'-"-'""^"'* ?"'"«"5 


1 1 <"- 1- 5E IS 'o i.-n,-ni ,.-1 n ei m Ti rj CT " "'■- ■- — — = o» 


£. i b«c:i = cce-me:>-'e»o?> «.<=F.a>-»« 



ALCOnOLOMETRY. 





s 


Mil, r,TrriTi ,-| - , , 


o'of-'-*—* wef 
















s 


|NiMMiS5;.5-.:.:.53 


oo^-- ««-«-, 




s 


M ' ' 1 1 oV*»«»Mo.-.--^-o-o- 


o-o«---er«-rf 




s 




e,„^o„„„ 






1 




s 

-i 

-1 


[11''! «.■«'«-• V «■«■*■ 5- --5 5- 


^•53355;- 


^ 


! l55~-S5S5S5;:-5335; 


1 


< 


=■ S' B »' L- .- 5 iTo .- * « IN ,! -■ = =• 


^■s-:-3S5v 


s-5a:-5:!-;;-5s-:-:-«-s-3:-5s- 


p..... 


T 


si 


=- o'oTb «■ tC«- o «■ «- ,-« no.-- = o- 


o =---««' W 














"S 


; -■ a »■»- «- r.'.~' o « « *' *-«- el nJ *- 3- 


~ M a r- v-w n ri 
oo'r--ei-«---.o 


■ 


ll. 


[ So-o-SSS'-So'c-^J^SSSS 



M j 


^- = ='a «r« r.- o o-« ^- ^' » «• -* o'o- 


oo-^-eJ«^-« ■ 










i-i 




t"""" 


-! 


— ;-.- ^T--*-w «-i,TT^-BS-«*-«-BO-o.- 
















I M -- =- o" a aTr-'t-' o « «■ »'»' « ^- ^' e 


o--'n-«Vo- 






'=..^.„ 






o -r--ef «--*-«- 








u : 


i S-^"^'o-a'S'S-'-S-S3-Vn-S---3S- 


-0,2 

i|b 

2.9 
8,7 

6|6 


1 


t> r'"-""""""""""-- 


22L~2SSS 1 



308 THE ETHYL GROUP. 



206 Determination of Alcohol in Beers and Wines. — The 
percentage of alcohol contained in liquids such as beer, wine, &c., 
in which other materials besides water and alcohol are present in 
solution, cannot be directly ascertained by the use of the hydro- 
meter. In such cases the simplest plan is to take a measured 
volume of the liquid and to prepare pure aqueous alcohol from 
this by distillation, and then to determine its volume and specific 
gravity. For the purpose of making such estimations, which often 
require to be quickly and accurately carried out, an apparatus has 
been devised by Descroizelles, which was afterwards improved by 
Gay-Lussac, and others. Savalle uses an apparatus, the construc- 
tion of which depends upon the same principle as the rectifica- 
tion of spirit and is shown in Fig. 80. The liquid to be exa- 
mined, several liters of which should be used, is brought into the 
still, a, and heated with gas to the boiling point. The vapour 
passes through the tube 5, to the worm c, cooled by the water 
d. When the water in c becomes warm, the vapours condense in 
the cooler, and the distillate is collected in the cylinder e. For 
liquids which do not contain more than 16 per cent, of alcohol it 
is only necessary to distil off one-third ; if they contain more, a 
larger amount must be driven off. In this way 5 liters of wine 
give 751 cbc. of a distillate containing 56*99 per cent, and hence 
the wine contains ""^^^^ = 856 per cent. By means of this ap- 
paratus the amount of spirit in weak alcohols can be ascertained 
even when they contain as little as 0*01 per cent. 

If only a small quantity of liquid be at disposal, Gay-Lussac's 
wine-tester as modified by Mohr may be employed, and by 
means of this instrument the quantity of alcohol in so small a 
volume of liquid as ten cbc. may be determined with tolerable 
accuracy. For this purpose 10 cbc. or a larger volume, is 
measured out in a pipette, and brought into the flask. Fig. 81, 
an equal volume of water added, and the whole distilled over 
into a small wide flask upon the neck of which a mark is made, 
indicating exactly the same volume of distillate as that of the 
original wine or beer. In order to prevent the liquid from 
bumping it is advisable to add a small quantity of tannic acid, 
and to distil the liquid until the distillate comes nearly up to 
the mark. The distillate is then cooled to the normal tem- 
perature, and water added to fill up to the mark, and the 
whole again weighed. The weight in grams divided by the 
number of cubic centimeters gives the specific gravity. Another 
arrangement for distilling wines is shown in Fig. 82. 



KffriMATION OF ALCOHOL IN WINEa 



307 The ebullioscope is an iD&trument by means of which the 
amount of alcohol in a liquid can be determined by ascertaining 
its boiling point, na this is higher the less alcohol is contained 
in it. YariouA kinds of instruments of this sort have been 
made. Fig. 83 shows the construction of Fohl's ebullioscope. 




Usually the thermometer has an empirical division from which 

the percentage amount can he directly read off. According to 

Griessmaycr ' the ebullioscope of UalHgand * is the best for the 

' DiDgler, Polyl. Journ, ccxHii. 282. ' Campt. lUnd. Ixm.-llll. 



TEsrriNa of wines akd beeks. 



determinatioD of the amouut of alcohol contained id beer and 
wine, icasmuch as the process is much simpler and quicker 
than by the method of distillation. For over-proof spirit this 
method is, however, perfectly useless, because the difference in 
boiling-point becomes very slight for a considerable difference 
in the percentage of alcohol. 




Fig. H^ shows Crockford's patent spirit indicator, as described 
in Tliudicumand D up re's treatise on wines. A small condenser 
13 fixed on the top of the boiler to prevent loss of alcohol during 
boiling. 

208 Another instrument designed with the same object 
depends upon the determination of the tension of aqueous alcohol 
at 100° as determined by Plucker.' The instrument, shown in 



THE ETHVL GROIT. 



Fig. Hq, has been made by the well-koown glass-blower Gelssler,* 
and termed by him the raporitneUr. The tube (o) Fig. 85 
lirst contains merairy up to the mark, and then is filled 
completely with the beer or wine to be examined. It is then 




fMtene<l tnt^i lh<: ground neck of a Ryphon barometer tube 
(B), ibtH lifiiin placed in a vertirnl position, and then 
exposed t> the action of steam coming from boiling water, 
when the ]i<]ui<l evolves a large quantity of vapour and 
the nierniry in the tube if) driven up tn a certain height 

' P-liri. C'almlh. 1S34, 14^8. 



CBOCKPORD'S PATENT SPIRIT ISDICATOR. 



according to the amouot of alcohol contained in the liquid. 
An empirical scale is placed on the barometer tube by 




Tta. 85. 



means of which the percentage of alcohol can be rend off. 
Should the liquid under examination contain carbon dioxide. 



THE Ermx GRorp- 



tbis gas must, of cuurse, be removed before tbe opention, 
aiid this is best effected by ahaking it with 
freshly barnt lime. If the solution contain 
a large quautitr of dissolved matter, the re- 
sults are usually inexact, and, in this case, a 
given vulume of the liquid is distilled off and 
this treated as abovK described. 

Alcohol expands on warming much more 
rapidly than water; and founded upon this pro- 
perty Silbermann* has described an inatniuent 
termed a dUaiomeUr (Fig. 86). This conaista 
of a thermometer tnbe baring a scale etched 
upon it, into which a certain volume of the 
liquid is brought at £5°, and the expansion 
•jbser\'ed which this undergoes in heating to 

.-,o\ 

Many other methods are employed for de- 
tenniuing the strength of alcoholic liquidB. 
For a (lescription of these wo must refer to 
the uiidermentioued works.* 
''"'■ *^- 309 The following table gives the percentage 

4if alrohul cuntaiuc-d in vatiou.o wines and other fermented 

liqiK 



P. It (old bottled) . 
,, (newly bottled) 
Montilla sherry (1S.'>4 
Fine Marsala 
Madeira , . . . 
Jit-auue .... 
< iberingelliciuit r 
Asiiman nshiiuacr 
( 'hatcAU-Latitte 
Urdiuary Bordeaux 
.loliannisborger (\mi] 
Kiidosilieimer 
Aucrbachcr ... 
Burton Ale . . 
Kiliiibur^h Alo . . 
London Porter . . 
Munich Lagcrbicr . 
Sflienkbier . . . 
BiTlin Weissbier 



io-i 



161 

13:> 

9 + 



;V7 to 61 
5 -t to 6-9 



i. 2A7 ; Slammer, BnttkHltrrinbrftitif 



ALCOHOL IN WINES AND BEERS. 315 



The value of a wine does not, as is well known, depend upon 
its percentage of alcohol. Thus, the price of Chateau Lafitte 
containing only 8*7 per cent, is much higher than any ordinary 
port containing about 20 per cent. So, too, the percentage of 
sugar and of acids contained in the wine may be almost 
identical in the case of different wines of the same class, as for 
instance, in clarets, but the value of these various clarets may 
be very different. On the other hand, it appears that the total 
amount of solid constituents contained in a pure wine bears a 
very distinct relation to its value, which is also of course greatly 
determined by its bouquet 

In order to show the presence of alcohol in beer or wine the 
liquid may be boiled in a flask having a tube 1^ m. long and 
1 cm. wide fastened to it, and which serves as a rectifying 
column so that the alcohol vapour becomes so concentrated that 
it may be lighted at the end of the tube.^ 

When pure alcohol is taken in small quantities in the form 
of good beer or pure wine it appears to improve the diges- 
tion by an increase of the secretion of the gastric juice. 
Especially for old persons and those having weak digestions 
it is useful, and indeed wine and spirits are frequently termed 
the milk of old age. In large doses however it acts as a 
powerful poison. 

After the imbibition of alcohol small quantities of this sub- 
stance are found in the urine. ^ 

The feeling of warmth experienced after indulgence in alcohol 
is a subjective phenomenon, as the temperature of the body sinks 
under such circumstances from O^'o to 2°'0, according to the 
quantity of alcohol taken. ^ If alcohol be taken during a 
meal no such diminution of temperature is observed.* 

The higher homologues of ethyl alcohol exert a still more 
distinct physiological action than common alcohol does, and to 
these is especially to be ascribed the evil effects which ensue 
from an indulgence in common brandy.^ Manufactured wine 
also produces, even when taken in small quantity, headache 
and unpleasant symptoms, whilst pure wine does not produce 
these effects unless it is taken in excess. Wine is manufactured 

' Tollens, Bcr. Deutsch, Chem. Ges. ix. 1540. 

' Lieben, Ann. Chem, Pharm. SuppL vii. 236 ; Dupre, Pi'oc, Roy, Soc. xx. 
2..8. 

» Binz. Ber. Daitsch. Chem. Ges. v. 1082. 

* Parkes, Proc, Hoy. Soc, xxii. 172. 

^ DnjardinlWaumetz and Audige, Compt. Rend. IxxxL 1/>2. 



316 THE ETHVL GROUP. 



bj Gall s proces bj the adibcion of starch sugar before fer- 
mentation to a grape-must poor in sugar. The starch sugar i^ 
obtained from potato-starch, and is. hoirever, not pore, but leaves 
behind a qoantitv of unfermentaUe residue, which, as experi- 
ments with dogs have shown, acts in a similarly poisonous 
manner to potato fusel oiL^ 

2IO Uses of Alcohul in tlur Ari^ — Pure as well as impure 
spirit of wine is used for a great variety of purposes. In the 
first place, strong alcohol is largely employed as a fuel, as 
it rearlily bums with a non-luminous and smokeless flame. 
Before Bunsen invented his well-known gas-lamp, spirit-lamps 
were in general use in almost all laboratories. 

In the second place, it is largely emjdoyed both in the arts 
and in scientific investigations as a solvent, and as a means of 
separating one substance from another. This depends on the 
fact that many bodies which are insoluble or difficultly soluble 
m water, dissolve in alcohol, and, on the other hand, that mxay 
substances readily soluble in water do not dissolve in this 
menstruum. Thus, for example, the carbonates and sulphates 
of the metals are insoluble in alcohol; whilst some chlorides, 
bromides, and iodides readily dissolve, others again not possess- 
ing this property. Raymond Lully observed long ago that this 
substance creates a turbidity in a solution of ammonium 
carlK>nate : ''Hie etiam spiritus (animal is) habet proprietatem 
congelandi spiritus vegetabilis vel aquam vitae perfecte rectiti- 
catum. Nam earn in salem convertit, qui plurimas proprietates 
et virtutes excel lentissimas habet." Boyle showed in 1675 that 
stron;( alcohol precipitates a saturated solution of common salt, 
and Boulduc in 1726 employed alcohol for the separation of 
salts in mineral-water analysis. In 1762 Macquer determined 
more exactly the solubility of many salts in alcohol, and 
Lavoisier, as well as Bergmann, used this solvent in their 
analytical researches. At the present day its employment in 
analysis is somewhat restricted. It is, however, used in 
qualitative analysis for the separation of strontium chloride 
from barium clilori<le, an<l in quantitative analysis for washing 
preci])itates which are slightly soluble in water, such as lead 
HuI])hato, lea^l chloride, potassium platinichloride, ammonium 
platinum chloride, &c. 

Sjiirit of wine is likewise employed in the laboratory for the 
purification of commercial caustic potash which dissolves in it, 

» Schmidt, Bitderm. Ctntralbl, 1879, 712. 



METHYLATED SPIRIT. 317 



leaving a residue of carbonate, sulphate, alumina, &c. Amongst 
the solid and liquid elements, phosphorus and sulphur dissolve 
slightly in alcohol, and iodine and bromine to a much larger 
extent 

Some gases are absorbed by alcohol even in larger quantity 
than by water. In this respect the hydrocarbons are especially 
distinguished. The coefl&cients of absorption of the different 
gases in alcohol have been determined by Carius.^ 

Alcohol is used as a solvent especially for ethereal oils, resins, 
alkaloids, and many other carbon compounds which are insoluble 
or difficultly soluble in water. For this reason it is em- 
ployed in the preparation and purification of such compounds, 
and it is also used for the manufacture of tinctures, essences, 
liqueurs, perfumes, colours of various kinds, varnishes, lacs, 
polishes, &c. 

Methylated Spirit, — For most of the above purposes methylated 
spirit is employed instead of pure alcohol. In this country a 
heavy excise duty on spirit of wine has always existed, and 
the manufiacture and sale of this aiticle is placed under strict 
supervision. Hence many branches of manufacturing industry, 
as well as the investigations of the scientific chemist, were, in 
this country, much impeded, until in 1856 the late Mr. John 
Wood, Chairman of the Board of Inland Revenue, obtained 
Government permission for the manufacture of methylated spirit 
which is sold by licensed dealers free of duty. This substance 
is a mixture of 90 per cent of spirit of wine of density not less 
than 0830 sp. gr., and 10 per cent, of purified wood-spirit. Such 
a mixture is unfit for human consumption, and the wood- spirit 
cannot again be separated from the spirit of wine by any 
commercial process. 

Methylated spirit is largely used instead of pure spirit in the 
manufacture of the aniline colours as well as of ether, chloro- 
form, fulminating mercury, iodide of ethyl, olefiant gas, and a 
number of other substances. The same mixture is used for the 
preservation of anatomical preparations, and of small animals 
and other zoological specimens. 

The possibility of thus obtaining cheap alcohol has moreover 
beneficially influenced the recent progress of organic chemistry 
in this country.^ 

* Ann. Chem. Phann, xciv. 129. 

' " Report to the Chairman of Inland Uevenue on the Supply of Sprit free 
from Duty," hv Professors Graham, Hofroann, and Redwood, Quart. Jmim. Chatu 
iS'oc. viii. 120 (1856). 



318 THE ETHYL GKOUP. 



211 Detection ofAkolwh — In order to detect small quantities of 
alcohol in an aqueous liquid, it is gently warmed, a few crystals 
of iodine added, and then so much caustic potash that the 
solution just becomes colourless, when, either at once or after a 
short time, a bright yellow precipitate of iodoform is thrown 
down. In this way one part of alcohol may be detected in 
2,000 parts of water, but in the case of such dilutions the liquid 
must be allowed to stand for a night in order to allow the pre- 
cipitate to subside. The deposit consists of microscopic six- 
sided tablets or six-sided stellar groups.^ 

Alcohol may be detected in presence of ether, chloroform, &c., 
by withdrawing it from such liquids by shaking with water, and 
then acting on the aqueous extract as above described. It must, 
however, not be forgotten that several other substances yield 
iodoform by the same reaction. 

Another good reagent for alcohol is benzoyl chloride. K a 
few drops of this be added to dihite alcohol and the mixture 
gently warmed, ethyl benzoate is formed. As, however, the 
chloride is only slightly decomposed by water, it is better to add 
caustic potash when the characteristic smell of the ether is 
rendered evident. By means of this reaction 01 per cent, of 
alcohol may be detected.^ It must, however, be remembered 
that other alcohols treated in the same way yield ethers 
possessing a similar smell. 

If large quantities of an aqueous liquid have to be examined 
for alcohol, it is, of course, best to fractiouate the liquid, the first 
portions coming over being collected and concentrated, until, 
on addition of potassium carbonate,' a layer of light liquid 
separates out, which then can be further examined (Lieben). 

In order to (hitect the presence of fusel oil in spirits of wine, 
the simplest plan is to pour a fow drojw on to the hand and rub 
the palms together, when evaporation takes place, and the more 
dithcultly volatile fusel oil remains on the skin and can readily 
be detected by its unpleasant smell. A more reliable process, 
however, is to allow the liquid gradually to evaporate in an 
open glass dish, and then to notice the smell of the residue. 
As fusil oil consists chiefly of higher homologues, the spirit 
under examination may be oxidized by the action of a solu- 
tion of potassium dichromate in dilute sulphuric aci«l, when 
acetic acid is mainly produced, together, however, with it«? 

- Hcrtlu'lttt, *'*nttftt. limti, ly.xiii. 4i»»J. 



DETECTION OF ALCOHOL. 319 



homologues, if fusel oil be present. These latter, in contradistinc- 
tion to acetic acid, distil over first with the aqueous vapour, and 
from the smell of the first portions of the distillate it ia often 
possible to detect the presence of the higher homologues of 
acetic acid. A more certain plan is to saturate the acid dis- 
tillate with baryta-water, and to determine the quantity of 
baryta contained in the salts produced.^ 

It sometimes happens in this country that the unpleasant 
smell of the methylated spirit is partially removed by means of 
acids or oxidizing agents, and that the spirit thus obtained, 
though still containing methyl-alcohol, is sufl&ciently tasteless 
to be used for adulterating the commoner kinds of whisky and 
other alcoholic liquors. According to Dupr^ such an adultera- 
tion may be detected by Geissler's vaporimeter, as the tension 
of methyl alcohol is much higher than that of spirits of wine. 
Its presence may also be ascertained by oxidizing the spirit as 
above described ; in presence of methyl alcohol an evolution of 
carbon dioxide is, under these circumstances, observed. 

Methyl alcohol, as well as its various derivatives, are largely 
used (as has been already stated) for the preparation of aniline 
colours. The wood-spirit used for this purpose must, however, 
not contain any ethyl alcohol, as the presence of this substance 
greatly influences the shades of the colours produced. In order 
to detect its presence the alcohol is treated with permanganic 
acid, which oxidizes the methyl alcohol to carbonic acid and the 
ethyl alcohol to aldehyde. The mixture is then distilled, and a 
solution of rosaniline, rendered acid by sulphuric acid, added 
to the distillate. If the methyl alcohol be pure this will 
remain yellow, but in the presence of aldehyde it becomes 
violet or blue coloured.^ The alcohol to be tested may also be 
heated with double its volume of concentrated sulphuric acid, 
whereby the methyl alcohol is converted into methyl ether, and 
this is readily soluble in water and concentrated sulphuric acid, 
whilst ethyl alcohol is almost entirely resolved into olefiant gas, 
which is only slightly soluble in water and dissolves but slowly 
in sulphuric acid, and is easily recognised, and its quantity ascer- 
tained by its reaction with bromine. The other bodies usually 
present in common wood-spirit do not yield any ethylene, and in 
this way 1 per cent, of alcohol may be readily detected.^ 

^ Dupre, Pharm. Journ. Tram. (3) vi. 867. 
^ liiche and Bardv, Compt. Rend, Ixxxii. 768. 
^ Berthelot, rompt. nnid. Ixxx. 103i'. 



320 THE ETHYL GROUP. 



212 Decompositions of Alcohol, — ^Alcohol serves as a point of 
departure for all other ethyl compounds. These can be obtained 
from it by various reactions, and hence the action of chemical 
agents on alcohol has been most carefully examined. In some 
of these, the radical ethyl remains unchanged, whilst in other 
reactions, however, the radical undergoes alteration. Thus, 
for example, by a moderate oxidation, aldehyde, CjH^O, and 
acetic acid, CjH^O,, are formed. This change can also be 
brought about by the oxygen of the air, but not immediately, 
for concentrated as well as dilute spirit of wine are not at- 
tacked at the ordinary temperature by oxygen. If, however, 
platinum-black be mixed with alcohol, or if this powder be 
placed on paper and moistened with alcohol, oxidation takes 
place, accompanied by an evolution of heat and followed by 
ignition of the alcohol. Addition of water diminishes the 
intensity of this action. Upon this observation of Edmund 
Davy's, Dobereiner founded his vinegar-lamp. This consists 
of a flask filled with alcohol, in the neck of which is placed a 
glass funnel, upon which slightly moistened platinum-black 
is spread, whilst a piece of cotton wick brings the alcohol into 
contact with this powder. The flask or bottle stands on a 
dish, over which a glass bell-jar is so placed that a small 
amount of air is allowed to enter. In this way the alcohol 
undergoes oxidation, the vapour of acetic acid being formed, 
and this gradually collects on the inside of the bell-jar. Accord- 
ing to Dobereiner, platinum-black used in this way is an 
excellent means of detecting small traces of alcohol. If a drop 
of alcohol be allowed to evaporate in 50 or 60 cbc. of air and 
a small quantity of platinum-black put into this, the formation 
of acetic acid can be readily noticed.^ 

When strongly heated platinum wire or platinum foil is 
brought into a mixture of air and alcohol vapour, the metal 
gradually becomes heated to redness (Vol. II. Part II. p. 307). 

Whilst pure alcohol does not undergo spontaneous oxidation 
on exposure to air, beer or wine soon becomes sour with 
formation of acetic acid. This depends on the presence of nitro- 
genous Ixxlies, which act as carriers of oxygen from the air to 
the alcohol. 

Oxidizing bodies, according to their nature and the mode in 
which they act, convert alcohol into other products in addition 
to alcohol and acetic arid. Thu.s, for exam])le, if strong nitric 

* Ginclin's Unndbookf viii. *J07. 



ALCOHOLATES AND ETHYLATES. 321 



acid be added to alcohol, an explosive action takes place, and, 
in addition to the oxides of nitrogen and the above-named com- 
pounds, we find amongst the products ethyl nitrate, fonnic acid', 
oxalic acid, hydrocyanic acid, &c. A more moderate action 
yields chiefly glycollic acid, and aldehydes of oxalic acid. 

A mixture of dilute sulphuric acid and manganese dioxide, 
as well as a solution of chromium trioxide, yield acetal, 
CjH^COCoHJg, together with aldehyde and acetic acid. If, 
however, strong alcohol be dropped on to dry chromium tri- 
oxide, ignition and complete combustion take place. 

Alcohol is also readily acted upon by chlorine and bromine, 
oxidation-products being first formed and then substitution- 
products being produced, the description of which will be found 
later on. 

Alcohol vapour may be heated to 300° without decomposition 
occurring. At a red-heat, however, dry distillation commences, 
hydrogen, marsh gas, ethylene, acetylene, benzene, naphtha- 
lene, carbon monoxide, aldehyde, acetic acid, phenol, &c., being 
produced (Berthelot). 



The Alcoholates. 

a 13 This name was given by Graham to compounds discovered 
by him in 1828,^ and formed by the combination of anhydrous salts 
with alcohol, the latter substance playing the part of water 
of crystallization. Other chemists have increased our know- 
ledge of these compounds,- and from these investigations it 
appears that only those salts form alcoholates which are easily 
soluble in water, and which usually contain water of crystal- 
lization. The following are some of the more important of 
these : 

LiCI + 4C2H^O, is formed with evolution of heat when lithium 
chloride is brought into contact with absolute alcohol. It 
crystallizes on cooling in nacreous glistening prisms. 

CaClg+^CgHgO, is produced in the same way as the foregoing ^ 
compound, and forms a white crystalline mass. 

MgClg + GCgHj^O corresponds closely to the lithium compound 
and is very deliquescent. 

» Phil. Mag iv. 26,'>, 331. 

^ Cboilncw, Ann. C/o:m. Pharm. Ixxi. 241 ; I-.€vy, Ann. Chim, Phys, [3], xvi. 
309 ; Robiquet, Journ. dc Pharm, [3], xxvi. 161 ; (le JiUyncs, Joiim. Pr. Clitin, 
Ixxx. 503; Bauer, ih. Ixxx. 3r»l ; Simon, ih, [2J. xx. 371. 

VOL. III. Y 



y&*t TliE ETHYL GEOr?. 



Mg'NO^j-rCCjH^O forms a peariy orysiaLiae 
In ^^YvCihu to these, manT other chlorides and nitrates, as well 
as certain bromides, form alooholates. 



Ethtlates, 

214 Tbe^se componnds are formed from alcohol by the re|daoe- 
ment of the hydrogen of the hydroxyl by metals, and this may 
be accomplished in a variety of ways. The ethylates are readily 
decompose'l by water with formation of alcohol and the cor- 
responding hydroxide. 

Potavnt/m Ethjflate, C^H^OK. Potassium dissolves in abso- 
lute alcohol with evolution of heat and liberation of hydrogen. 
Tran.sparent colourless crystals separate out on cooling the con- 
centrat^.'fl solution, and these contain alcohol of crystallization. 

fi/xlium Ethylnte, C^H.ONa, is obtained in a similar way,* 
and forms a mass consisting of transparent needles, which 
liave the composition C^H^ONa 4 2C2H^O. The alcohol of 
crystallization is easily lost in a vacuum over sulphuric acid. 
Wanklyn obtained crystals of the formula C\H.ONa + 3CjH^O, 
melting at 100' without losing their alcohol of crystallization, 
which, however, escapes at a higher temperature, and is com- 
pletely rlriven off on heating to 200'. The comjx>und, free from 
alcohol, is a light amorphous powder, which, when prepared in 
:i\mtu('M of air, is perfectly white, and may Ik? heated to 290*^ 
without any <lecoinposition taking plar e.- 

ThnU'uivi KthylcUr, C2Hr,0Tl, is formed by the action of 
alcohol vapour on finely divi»led thallium. It is a colourless liquid 
having a sjKJcific gravity of 3*5."), and possessing a refracting 
pr)w<»r as strong as that of carbon disulphide. It solidifies at 
-.T, ;ind is easily inflammable, burning with a bright green 
flame. ^ 

linrivm Ethyl ntc, (C2H.0)^Ba, is formed by dissolving anhy- 
drous baryta in al)solute alcohol and boiling, when a precipitate 
is thrown down. This must be dried at 100"* in a current of 
hydrogen, and is difficult to obtain in the pure state.* 

Zinr Etkyhte, {fj^r())Jun, is a white amorphous mass formed 
by the slow oxi<lation c»f zinc etliide, 

^ (viH'riti Varn*. Journ. S'-irnfr Phijs. iil 273. 
- Wanklyn, Phil. Mmj. [41, xxxvii. 117. 
' Lnniv.*'W»;>/. nnvi. Ixv.' 8-J»5 ; lix. 780. 
* llerllii'lot, //«//. Si^. rfiim, [21, viii. 389. 



ETHYL ETHER OR ETHYL OXIDE. 323 



Aluminium Uthylate, (C2iifi)QA\^ This is formed by the 
action of iodine and fine aluminium foil on alcohol, hydrogen 
being given oflf, whilst the compound (021150)3 Algl, is also formed 
in small quantities ; when the whole is heated to 270°, the latter 
compound decomposes into ethyl iodide and alumina. If the 
residue be distilled in a vacuum, or under diminished pressure, 
aluminium ethylate passes over, solidifying to a yellowish white 
mass, melting at 115°, and boiling at the same temperature as 
mercury.^ It is somewhat soluble in absolute alcohol, and is 
quickly decomposed by water. 



ETHYL ETHER OR ETHYL OXIDE. 

a 15 Raymond Lully, as well as Basil Valentine, examined 
the action of sulphuric acid upon spirit of wine, and hence it is 
generally assumed that they were acquainted with ethyl oxide, or 
ether, as it is still generally termed. This is possible, for Basil 
Valentine speaks gf a spirit obtained in this way which has 
a " subtle, penetrating, pleasant taste, and an agreeable smell." 

We owe our special knowledge of the existence of ether to 
Valerius Cordus, a German physician, who died in Italy in 
1544. His process for the preparation of this body was pub- 
lished by Conrad Gessner in 1552, and occurs in the later 
editions of the first German Pharmacopoeia, this work, which 
was first published in 1535, having been re-edited by Cordus 
at the request of the Council of Nuremberg. Accordmg to 
this receipt, equal parts of thrice rectified spirit of wine 
and oil of vitriol are allowed to remain in contact for two 
months, and then the mixture is distilled from a water- or sand- 
bath. The distillate consists of two layers of liquid, of which 
the upper one is the oleum vitrioli dulce vcrum. 

Various chemists mention this body, but at the beginning 
of the eighteenth century the details of its preparation appear 
to have been almost entirely lost, although, at this period, a 
mixture of spirit of wine and ether was used in medicine ; 
indeed it seems not improbable that Paracelsus employed such 
a mixture. It was, however, first brought into commerce by an 

' GlaUstone, Joum, Chem, Soc, 1876, i. ir»8. 

Y 2 



324 tup: ethyl group. 



apothecary in Halle, under the name of Panacea Vitrioli, and 
afterwards having been recommended by Hoffmann, it received 
the name of Liquor anodymi8 Hoffmanni, or Hoffmann s drops. 
Under this name it soon became generally known, and even to 
the present time is thus designated in Germany. The pre- 
paration of this medicine was long kept secret, and the positive 
existence of ether was not proved uutil it was first prepared 
free from spirit of wine, and then it was found that it swiius 
on the surface of water, and is not miscible with this liquid. 

In 1730 Sigismund Augustus Frobenius published a memoir 
in the Pliilosophical Transactions,^ entitled, " Of a spiritits vini 
athereuSy* in which he describes, in general terms, the pre- 
paration of this compound, though without giving any details. 
Ho manufactured the ether in Godfrey Hanckewitz*s laboratory, 
and as he sold it at a high price, he endeavoured to keep the 
process a secret one, and in forwarding some of the new substance 
to St. F. Geoffrey, he writes, after extolling its virtues, as 
follows : " Paratur ex sale volatili urinoso, plantarum phlogisto, 
aceto valde subtili, per summain fermcntationem cunctis sub- 
tillissime resolutis et unitis." On the 18th November, 1731, 
he made experiments with ether and phosphorus before a 
meeting of the Royal Society, which are thus described 
by Dr. Mortimer, the secretary : ^ " He took a solution of 
phosphorus in the ethereal spirit of wine, which he called 
Liquor lurninosds, and poured it into a tub of warm water, 
whereuj>on it gave a blue flame and smoke, attended with so 
small a degree of heat as not to burn the hand if put into it 
He i>oured some of his ethereal spirit of wine upon a tub of 
cold water and set it on fire with the point of his dagger (which 
being first heated a little, he touched with it a ])iece of phos- 
phorus lodged beforehand on th6 side of the tub). After the 
deflagration the water was cold." 

In his second oommunication to the Societv he described 
more fully his method for the preparation of ether ; this descrip- 
tion was, however, at his request not made public until after his 
death in 1741, when the following receipt was published by the 
secretarv : ^ 

*' Take 4 lbs. in weight of the best oil of vitriol, and as much 
in weight (not measure) of the best alcohol, or the highest 
rectified spirit f'f wine. 

» xxxvi. 2ji3, Fcl). 19. 17-J0-3O. = Phil. Trans, Al.sJr. ix. .M72. 

=* Phil, Tram. Abiitlg. ix. :5M>. 



HISTORICAL COXCEllXIXG ETHKI^. S26 



** 1. First, pour tho alcohol into a chosen glass retort, then 
pour in, by little and little, ^ of oil of vitriol ; then shake the 
rotort till the two liquors are thoroughly mixed, when tho retort 
will begin to grow warm; then pour in more of the spirit of 
vitriol, and shake it again; then the retort will become very 
hot. Do not pour in the spirit of vitriol too fast, or too much 
at a time, lest the glass rotort, by being heated too suddenly, 
should burst; you must allow about an hours time for pouring 
in the spirit of vitriol, not pouring in above an ounce at a time, 
and always shaking the retort, till the whole quantity of the 
jwnderous mineral spirit is intimately united with the light 
inflammable vinous spirit. 

" 2. In the next place, examine witb^our hand the heat of 
the glass retort, and have a furnace ready, with the sand in 
the iron pot heated exactly to the same degree as acquired 
by the mixture of the two liquors ; take out some of the 
sand, and, having placed your rotort in the middle of the iron 
pot, put in the hot sand agaia round the retort, and apply a 
capacious receiver to it ; set it into cold water, and wTap it over 
with double flannel dippe<l in cold water. 

" Raise your tire gradually, that the drops may fall so 
fast that you may count Ave or six between each, and that, 
iK'Side this quick discharge of the drops, the upper hemisphere 
of your receiver ap{x?nr always filled with a white mist or 
fumes; continue this heat as long as they emit the scent of 
true marjoram. As soon as the sn)ell changes to an acid, 
suffocating one, like that of brimstone, take out the fire 
and lift the retort out of the sand, and change the receiver, 
for all that aiises afterwards is only a mere gas of brimstone, 
and of no use. 

" If you do not use the greatest precaution, the liquor in the 
retort will run over ; the fire must cease as f oon as the ethereal 
spirits are gone over, for there remains behind an oleirm vini, 
v.hich is extracte<l by the foice of the acid out of the spirit, 
which will arise, run over, and often cau.se explosions. 

" The second day, when your gla.ss is cold, infuse the 
remainder with half as much alcohol, and distil again as 
before, and you will have the same ; the third day again 
with as much, and proceed as at first, it gives it again. Go 
on as long as you can obtain any (of the ethereal spirit) 
till all turns to a carlo ; then separate it, and alcalize it with 
spirits of sf/if. ffnna/iitfr made without spirits of wine, till all 



:;2C THE ETHYL GROUP. 



c-nen'esceDce ceases, and distil it once more € Balneo Maria; 
M> is it ready for experiments.'* 

This mode of making ether was soon pretty generally adopted ; 
various German and French chemists having occupied them- 
strives with the preparation of this body. Amongst the more 
complete d^.-scriptions of the substance may be mentioned 
Baume's Dis^iertation sur lether (1757). 

By reason of its easy inflammability it was also called at this 
time ** naphtha/' a name originally given to rock-oil, whilst at 
the same time it was termed vitriolic ether, sulphuric ether, or 
ellur suiphnricus, and vitriol-naphtha, or naphtha vitrioli, inas- 
much as it was obtained by the action of sulphuric acid on 
;dcohol in much the same way as other similar volatile etliereal 
liquids are prepared by the action of other acids on alcohol. 

In 1800 Valentin Rose^ showed that the name sulpburic- 
ethc-r is a mihlearliug one, inasmuch as this substance does not 
contain any sulphur or sulphuric acid. Fourcroy* was the first 
to pro[K>und the idea that ether is formed from alcohol by the 
withdrawal of the elements of water; and he and Vauquelin' 
endeavoured to enforce this view by experiments, the results of 
which wcrrj confirmed in 1807 by Saussure's analysis of ether, 
and subsequently by Gay Lussac's analysis in 1815. It was then 
lif;Iieved tli.it the action of sulphuric acid upon alcohol could be 
simjily I'Xplainod by the fact that this acid removed from the 
alcohol either the elements of water, or water already present 
in the conqiouiKl. Many facts, however, contradicted this view. 
Thus, as we have seen, Frobenius had observed that the 
residue in the manufacture of ether may again be employed 
for a further ronversion of alcohol into ether, a fact which was 
confirmed by many other chemists, and especially by Cadet 
in 1774. 

By tlio introduction of a simple process of manufacture the 
price of ether was considerably diminished, as is seen from a 
discussion between Beaume and Cadet, in which the former 
criticised the new method of Cadet, and the latter stated that 
whilst Beaunir sold tin* compound at twelve livres per ounce, 
he char^^t^d <m\y forty sous for the sani»? quantity. 

It is to Boullfiy* that we owe the discovery of the continuous 
process now univrrsully employc«l for the manufacture of ether, 
clcpending on the t:u-t that a small quantity of sulphuric acid 

' Si'hrnr. Jt^itm. iv. •2.'».'{. - Khiurnf.s fT/ftJifniiu' Xnfur-'f** rf dr ('/ii)tn>, 

■* Srhn-r. Jntnn. vi. <'". * .'•*'/;», }'hnf},i. \. 07. 



THEORIES OF ETHERIFICATION. 327 



is suflScieut to convert a large quantity of spirit of wine into 
ether. From this observation it appears very improbable that 
sulphuric acid acts in this case simply as a hygroscopic sub- 
stance ; indeed, it soon became evident that this explanation was 
insufficient, because it was found that the whole of the water 
produced in the reaction distils over together with the ether, 
and it can scarcely be imagined that the sulphuric acid first 
exerts its power of removing water from the alcohol and then 
immediately parts with the water again which distils over with 
the ether. 

216 Theories of EtJierification, — As in many other reactions 
where a sufficient explanation is wanting, chemists (as well as 
other men) have long been in the habit of taking refuge in a 
name, and this peculiar action of the sulphuric acid was termed 
a catalytic or contact action, 

** Denn eben wo Begriffe fclilen. 
Da stellt ein Wort zur rechten Zeit sich ein." 

This catalytic hypothesis was first proposed by Mitscher- 
lich,^ and Berzelius gave his adhesion to the view. These 
observers omitted, however, to notice that the first action 
of sulphuric acid on alcohol, in the manufacture of ether, is 
the production of sulphovinic acid (hydrogen ethyl sulphate). 
This fact did not, however, escape the observation of Hennell, 
who found that a concentrated solution of this acid yielded 
ether on distillation ; whilst a dilute solution, on similar treat- 
ment, yielded only alcohol. This subject was more care- 
fully investigated by Liebig,^ who came to the conclusion 
that ethyl sulphuric acid which is first formed, decomposes at 
a temperature of 126° to 140° into ether, sulphuric acid, and 
anhydrous sulphuric acid (sulphur trioxide), this latter com- 
bining instantly with the water formed in the reaction with 
production of sulphuric acid ; this again forming ethyl sulphuric 
acid with the alcohol, which is being constantly added. This^ 
according to Liebig, accounted for the continuous nature of the 
reaction. The simultaneous evolution of water and of strong 
sulphuric acid was explained by assuming that this latter only 
combined with the water in its immediate neighbourhood, whilst, 
in the other parts of the liquid, the passage of the ether vapour 
carried away some aqueous vapour with it. The singular fact 

' Fogg. Ann. xxxi. 273 ; liii. 95 ; Iv. 209 ; Taylor, Sc M>'m. iv. 1. 
" Ann. Phanti. Ix. 31 : xxiii. 39 , xxx. 129 



328 THE ETHYL GROUP. 



that ethyl sulphuric acid should be both formed and decomposed 
at the same time and in the same liquid was explained hj 
Heinrich Bose, by the suggestion that a diminution of tempera- 
ture sufl&cient to permit of the formation of ethyl sulphuric add 
took place at the point where the alcohol flowed in, but that 
the other portions of the liquid were sufficiently hot to cause 
the decomposition of this acid. Mitscherlich soon rendered this 
hypothesis untenable by showing that the continuous formation 
of ether may be carried on under circumstances in which no 
such local diminution of temperature can occur, as it 13 pro- 
duced equally well when a current of the vapour of alcohol is 
passed in, in place of the liquid.^ Upon thisj Leopold Gmelin 
remarked that at the point where the vapour enters tlie liquid 
we have an excess of alcohol present, and there the formation 
of ethyl sulphuric acid may take place more easily in conse- 
quence of the presence of this excess of alcohol. Qraliam next 
proved that ethyl sulphuric acid when heated by itself to 140* 
does not yield any ether, and that on addition of water only 
alcohol ia formed, whereas ether is produced when the ethyl 
sulphuric acid is heated with alcohol to 140^ It has already 
been stated that Hennell also found that when the acid is 
heated with water it yields alcohol, whilst a concentrated 
solution gives rise to ether; and the same fact was also ob- 
served by Sertiirner. In the latter case we must assume that 
alcohol is also formed, but that it contains a small quantity of 
water only, and forms ether with the excess of ethyl sulphuric 
acid present, which when dilute it cannot do. Still no com- 
pletely satisfactory theory of the formation of ether could be 
established upon the facts which were then known. In order 
to understand this it must be remembered that the equivalent 
weights were then in general use, and that the following 
formulae were adopted : 

Alcohol. Etliyl Snlphuric Acid. Ktker. 

217 Williamson's Theory of Ethcrijication, — Graham, like Mit- 
scherlich and Berzclius, assumed the existence of contact action, 
but shortly afterwards the classical researches of Williamson « 
placed the true theory of the continuous etherificatiou process 
on the firm basis of experiment. This theory of the fonnation 

"^ Jtmrn Chew. Soc. iii. 24, 

" Brit, AssiK, JirjHtrfs, 1850, p. 65 ; 2'hil. Mug, [-3] xxxvii. 850. 



WILLIAMSON'S ETHERIFICATION THEORY. 329 



of ether has played a most important part in the development 
of our theoretical views ; the recognition of its truth has rendered 
it possible to explain a large number of similar reactions, and 
it has moreover led to the discovery of many new groups of 
compounds. 

Williamson, adopting the views of Laurent and Gerhardt, 
gave to ether the molecular formula C^H^^^O, according to which 
this substance contains the radical ethyl twice. But according 
to the theory of types^ alcohol is derived from water by the 
replacement in it of one atom of hydrogen by ethyl, and hence 
ether, according to Williamsons view, must be regarded as 
alcohol in which the second atom of hydrogen is replaced by 
ethyl. To prove the truth of this he made the following experi- 
ment. By dissolving sodium in alcohol he first prepared sodium 
ethylate, or, as he termed it, ethylate of soda ; and upon this he 
acted with ethyl iodide, by which reaction he obtained pure 
ether : 

Naj"+C,H,J-C,H5J*'+Na /• 

This proof, however, did not satisfy him, for, according to the 
old theory, it might happen that in this reaction two molecules 
(or atoms as they then were termed) of ether, each containing 
half the number of carbon atoms, had been. formed. Williamson, 
therefore, acted with ethyl iodide on sodium methylate, and with 
methyl iodide on sodium ethylate, and in both cases he obtained 
a single compound, viz. methyl -ethyl-ether, and not a mixture 
of two compounds, viz. methyl-ether and ethyl-ether. In a 
similar way he obtained amy 1-ethyl- ether or the seven-carbon 

ether, J^^JJ^ ] ^ 

The formation of ether from alcohol and sulphuric acid could 
now be readily explained. Ethyl sulphuric acid is, in the first 
place, formed, and alcohol acts again upon this substance : 

(1) %^ } o - J{ j so, = ^'^JJ-. I so, + « } o. 

(^)clJo-^''^S^)«'^-c!ll:^--3iso,. 

Water and ether distil over, whiUt the sulphuric acid which is 
reproduced yields ethyl sulphuric acid again on contact with 



3o0 THE ETllYL GROUP. 



more alcohol, and bcuce the formation of ether becomes con- 
tinuous. That tliis is the true explanation of the process was 
clearly proved by Williamson by first preparing amyl-sulphuric 
acid and then treating this \s'ith common alcohol as in the 
ordinary continuous process. At first amyl-ethyl-cther distils 
over, then common ether, and the residue no longer contains 
amyl-sulphuric acid, but consists entirely of ethyl-sulphuric 
acid. As a further proof of the truth of his theory, Williamson 
used a mixture of ethyl and amyl alcohols and allowed this 
to act on sulphuric acid exactly in the same way as common 
alcohol is used in the ordinary preparation of ether, when, as 
he predicted, he obtained a mixture of amyl-ethyl-ether and 
amyl-ethor. 

Further confirmation of the correctness of Williamson s Wews 
was afterwards given by Berthelot.^ By heating 222 grams of 
ethyl bromide with alcoholic potash, this chemist obtained 
12 grams of ether ; whilst if according to the old view the ether 
had been obtained by a simple replacement of bromine by 
oxygen, only 7'o grams could have been produced. Hence it 
is clear that alcohol must take a part in the reaction : 

Br f + H J ^ ^ U / ^ " CM, / ^ ^ H / ^ ^ Br I 

According to this equation 15 grams of ether should have been 
formed, lut owing to the nature of the experiment it was 
impossible to avoid a certiiin amount of loss.* 

2i8 Ether can be prepan»d by a great number of other 
processes. Thus, for example, it is formed with evolution of 
heat by the action of ethyl iodide on dry silver oxide : 

2 C,H,I + Ag.O = (C.H,),() + 2 Agl. 

Til jJace of silver oxide, so<rium oxide, Na^O, may be used. 
The reaction then does not occur until a temperature of 180* is 
reaclKMl.^ 

Ktluris also formed when a haloi»l ethereal salt is heated 
with alcohol, or with a small quantity of water under pressure. 
If, however, the water be present in excess, al(M>hol is produced. 

The action of the hytlracids of the chlorine group on alcohol 

' Jiiunnil iff P/niriintrir^ {:lj^ xxvi, 2'», 

' Wmtz, AnH. fhihi. rhus. (:i], xlvi. *1'1'1. 

• t.r.i'iH'. liiiU. >'.-■. Chint. I'J), xxix. I.'i»». 



PREPARATION OF ETHER. 331 



also gives rise to ether, but this only when the latter is present 
in excess, as in the opposite case the haloid ethereal salts are 
formed. This reaction serves as an excellent example of the 
action of mass, to which Bertholet, in his classical Essai de 
Statique Chiniique,^ first drew attention. When two bodies act 
chemically upon one another they may give rise to various 
products according to the quantitative relations in which they 
stand to one another. And hence reactions which take place 
under certain circumstances may under other conditions be even 
reversed. Thus, for example, alcohol when heated with an 
excess of hydriodic acid yields water and ethyl iodide, but if a 
large excess of water be allowed to act on ethyl iodide, alcohol 
and hydriodic acid are formed : 



aH.oH 4- HI = an J + h,o. 



^'■■B^-^^ ' ^^* ^2"6 



If, in the first case, the quantity of alcohol be largc^ the ethyl 
iodide acts upon it t^o form ether : 

When ethyl iodide is heated with a small quantity of water, 
alcohol is first formed, and this is then converted into ether. 

From the foregoing it is distinctly seen that a small quantity 
of a haloid ethereal salt or its corresponding acid is able to 
convert a large quantity of alcohol into ether, and moreover 
that the water which is constantly formed will gradually retard 
and ultimately stop the reaction, inasmuch as the various 
products will then be held in a condition of equilibrium. 

Many chlorides, bromides, and sulphates convert alcohol 
into ether,^ but usually only at a high temperature. In this 
case the free acids doubtless are also fonned, together with 
basic salts ; and it is these acids which then act in the manner 
already described in the process of etherification, this reaction 
being brought to an end by the presence of the water which 
is formed, and the acid again uniting with the basic salt. 

The change of alcohol into ether can also be brought about 
by phosphoric and arsenic acids. The reaction is in this case 

» Paris An. xi. (1803). 

* Mnsson, yinv. Cheni. Phnrm. xxxi. 63 ; Knhlmann, ih, xxxiii. 97 and 192 ; 
Keyuoso, Ann, Chim. Phys. [3], xlviii. 386. 



;i;U THE ETHYL GliOUP. 

I'Kiully llic Siuiif us that of sulpliunc iioiil. In coiiseqiieiicc of 
Uhm iiiiiIkkI i>f i>R'piUiiti.)ii ctlier was at one time also termed 
nixi'iiii- mill jiliosptioi'ic ether. 

aig Mit nil I'll rltirt <\f Klhcr hij the Guniinnons Process. — For the 
[>ri')Hii'!ili<iii ><f I'lhtT on the hu^e or small scale the method 
i;iiijiliiyiiil hy BimHay 13 always adopted. A misture of sul- 
jilniiif iLi'iii and al-uhol is made hi such proportions that the 
lii]iiiil bulls at about 140°, the lulatioii varying accoriliug to 




lhl<»IIVll-lh ..t 


il,>> .« nstiimmt.. A 1 


ixmii' of .') parts of 


1111 |K'. .vnl,„ 


nil niili !> {Kirls nf (miii'i.-ii 


ralL'il snlplmrif a(;id 


i« H vi'iv ii'O- 


i.i,-. Till.- is l.catnl it, 


!i H:isk or L-ast-intn 


U.il..r. Tl..' .1 


■.■k ..fll>.. iK-k (Ki-. S7, " 


till' opi'niii^' of the 


Uiilvt 1- I'nriuK 


»:\ niih lh|-.'.-4ulH'S. Into 


oiiL'.if tlK'soa tuh.<- 


tw\\\v\ iH littfi 


I lli.'i' is <-i>iiiii'<'I<m1 with 


a niiidi'iisiiii,' app:i- 


tikUH. winl-i 


1 Mil- third iiiK'nin:.; a thi 


riioniotcr is plai-iil. 



PUOPERTIES OF ETIIKK. 3?,3 



which must dip into the liquid. The mixture is then heated 
to the boiling-point, and alcohol allowed to flow from the bottle 
(e) through the tube-funnel (which must also dip into the liquid) 
in such jjuantity that the temperature remains nearly constant. 

According to theory an unlimited quantity of alcohol can be 
thus converted into ether. Practice has, however, shown that 
the operation must be interrupted when a quantity of alcohol 
about six times the volume of that originally contained in the 
vessel has been added. This depends chiefly oh the fact that 
the materials used are never anhydrous, and therefore, that the 
mixture in the retort becomes after a while so diluted with 
water that the reaction comes to an end. Besides, the liquid 
does not wholly consist of sidphovinic acid, but always contains 
free sulphuric acid, and this gives rise to secondary reactions, 
blackening occurs, sulphur dioxide and water are formed, and 
the presence of this latter exercises a further retarding influence 
on the reaction. 

The distillate, which, together with ether and water, contains 
alcohol and sulphur dioxide, is then treated with milk of lime 
or caustic suila, and rectified from a water-bath, when the ether 
first passes over, still, however, containing some alcohol and 
water. To remove these, the distillate is allowed to stand over 
fused chloride of calcium, a method described by Lowitz in the 
year 170(5. The ether is then poured otf from the chloride of 
calcium and again rectified, when it is found to be pure enough 
for all technical purposes and for general laboratory use, although 
it still contains sniall traces of water and alcohol. This latter 
is extremely ditiicult to remove, and can only be completely got 
rid of by repeatedly shaking the ether with a small quantity of 
water, and continuing this operation until the wash-water no 
longer gives the iodoform reaction. It is then dried over 
calcium chloride, and the liquid poured off from this treated 
with sodium until no further evolution of hydrogen takes place, 
and again distilled from a water-batli. In this purification of 
ether a considerable quantity dissolves in the wash-water. 
This may, however, be regained by rectification. 

220 Properties. — Ether is a very mobile liquid having a pecu- 
liar odour which affects the head, and a burning taste. It boils 
at 84"0 (Kopp, Andrew^s) ; at O"" it possesses a specific gravity 
of 07:35(18, and at 15*" of 070240. It volatilizes quickly not 
only at the ordinary temperature, but at a much lower ix)int. 
The tension of ether vapour is as follows: — 



3i.^4 rzz 5 



^^" 






:::u5 'L^zi^. "T.-r Tic^iir. Trli-.-c. frrzi it* Lizt jpecinc ffiavity 
n:.iy >: r<-:ril rr.ii :::-* ^frj^ifl z-: iH-.Tl-ir li^e '."sirboQ dioiide, 
!,r:v.<. t*"1:l .ir i :J,':/.t rirli-jf^r r-iirirr. ir.«i care is needed 
::; w.;"k.:::_- '^i'.'z, lirj-r ^-iii.::::-f:f :: rth-rr. r:o llaaie bein^ per- 
!..:::^' ::. i> :i-.i,:.>. irl -liL I: i -i^^^ ^riii: wiry vf ether be 
:i.l- w^ i :. -I'-ii* ri:- :- \ •:'. ^-l 5T*A»->r a i^Lx:urr is obtained 
w :;:j-. tl \t ^« tr-s - ::L :lv :'. : >. ■: : r"--!:*- "^ i-rr. Tr.e hi^h specific 
cni^i^y v! 1:: -r Vij- -.7 :.. .j :*..- >:rik:=.^"v iL:-*"!: is f-.UowsL A 
sn.:vr. viUA'-:iv.- :" r::-rr :- :r "iji.: :-:: ;% iksk al-I :be short end 
of a i:'-^>> svr.':. i. 15 :r. i/:.: lv x-nTiriLrvr ic*:Te the surface 
of iho liiiuivi. I: 'l-r .ir-:?::^ ir.i I :i^ ol..: t :Lt: syphon be 
i:o\\ svwkvl '. u:. v::.-.r v;.T-:ur -A-ill :::"»■ i.-.v^ iri a continuous 
Mucuu. auvl a >::.^11 rv':i..iTr nv^v j>r r:l!«:i "v with it and the 

Kv»urv'ivY aiiii Vm; ^ivliL .<:^:^- rh'i* other when exiled to — 31* 

snstiUtiA s in Ion J wL:>:- ^'ii^tvi^ih^' tAo- :>. which, at — 44" form 

ii ^viiliuuvms s^uiJ crystal -iiic- ma?s, ThvL;irJ aiui )[itchell were 

\iiuMc 10 ivnrinn tl.is ?rai«.i:i-nt, aT.i 'Ax- latttr f un I that 

i»uiv othor rv^muins li«|ui»l a^ — '.t.V.i TLi- .fustir.n has lately 

twu iuvoslis:?^tod by Fran-Iiirn-'Ut,- and hi< «v.nohisioDs agree 

\fcUh Uuv^* ^*^ ^'*^* ^^^'^ latter ch».iiii>t<. H..- f..und that moist 

^hci\ ^lu*»^ i\H4od, dep<.»sit< crystals, ]»roba]i!y c«iii>isting of ii^e, 

huA be vli>l u\U obtain a solid mass at - 44 . This may be 

MVM^tK\l b^ the f:u't that not eiK.uJi watur was present, as, 

,^^^^w. ^^* Oiuthno, otlRT unites with ice t" torm a «^ryuhydrate. 

;j^^ A v\^4vwml. having the formula C\H,.p + i>H^O, was 

\|^ i i^^ ^ Hv Vnurx^t by quickly evaporating eilior on filter paper. 

% :w J -- J"^ ^. whicli is the minimum temperature obtained 

•, xxii. 259 • Brr. IkHtavh, Ckem, Gff. x. 830. 

• iym^fn Ii^ndu% Izxxvi. 7^>. 



DECOMPOSITIONS AND USES OF ETHER. 335 



It was formerly believed that ether, like oil, is insoluble in 
water, until Lauragnais showed, in 1 758, that ten parts of water 
was sufficient to dissolve the ether completely. According to 
Boullay, on the other hand, one part dissolves in fourteen parts, 
whilst Draper states that ten volumes of ether dissolve, in 100 
parts of water, at 11°. Concentrated hydrochloric acid dissolves 
it in much larger quantities than water. ^ On the other hand, 
one part of water dissolves in about thirty-four parts of ether. 
Ether is miscible with alcohol and wdth almost all other hydro- 
carbon derivative compounds as well as with carbon dioxide. 
Many solid bodies, such as resins, fats, alkaloids, &c., dissolve 
easily in ether. Some of these are soluble in aqueous ether but 
not in absolute ether. This is the case with gallic acid, and this 
reaction is so characteristic that it may be employed to ascertain 
the presence of water in ether. If the latter liquid contains only 
a little moisture the dry powder balls itself up ; if more be pre- 
sent it deliquesces to a thick syrup, which does not mix with 
the layer of ether above, and consists of a solution of tannic 
acid in aqueous ether.'* Many inorganic substances are soluble 
in ether; thus sulphur dissolves slightly, and phosphorus dis- 
solves in rather larger quantity. This latter solution, which 
becomes yellow on exposure to light, was formerly known as 
JEthcran phofqifwratus. Ether dissolves iodine and bromine in 
larger quantity, as well as chromium trioxide, ferric chloride, 
mercuric chloride, auric chloride, platinum chloride, several 
other chlorides and iodides, and some few salts. Various gases 
are also absorbed by ether, such as ammonia, which is taken up 
in considerable quantity, other gases being less soluble. Accord- 
ing to Regnault, ether undergoes a change when preserved even in 
well- closed vessels, assuming a different vapour- tension. If ether 
be contained in a flask with air, acetic acid is formed after some 
time ; this change taking place more quickly in presence of 
an alkali. On the other hand, Lieben states that pure ether, 
either alone or in contact with potash, lime, or sodium, does not 
undergo any alteration on standing, but that if water or fused 
sodium chloride, or calcium chloride, or anhydrous sulphate of 
copper, be present, a slow change takes place, the liquid 
exhibiting the iodoform reaction.'^ 

221 Drrrmfpoaitioiis of Ether. — When ether is heated with 
water and a trace of sulphuric acid to a temperature of 150 



-> g\0 



^ Draper, Chrm. x\>?r^, xxxv. 87. ' Bolley, Ann, Chenu Pharm. cxv. 63. 

■•* Brr. Dcutsch, Chrm. iv. 75S. 



i. ziz. r. x.iii. ' sLm .■ 



-.' IS.' :: := L-rr-^i :l:. \I lL-/ I: ^:L^.t W tr^rauJ with 
7 In .:. I : : ^:^ i: a T-rL.r-rr^vire o: '/ to 4\ ale. hoi an«l 



T - 



< ;H. I ■ * I I - "Hi* * ■ I)^- 

Mis-:; c.L-ts ir-.- 'iiv::..:^- v i ::i i siriiilai 'K^ay. the ra^lical 

c I." if:.::, J ::.r r.. ?: -.Xirl. :. ' ►ri:.^ cori-.vrred iniv* an aloohol.^ 
Iv.l.yl :.::':- i-? .:>> :-.r:..rl ::. :i vileii: rc:iotivu, pr.ibably 

r ::-.•.":. r vi-h xvvtiivl ,il :::.::/. -jiii i...i:.!v. '.\Kfch Li5 alreaJv 

- • • • 

]■•-:!. >::'-:T' i • 'Ah.:-!: vri.rr :* l-r-'irht :n .■■»ut:u-t with ic^.liue 



fll. I. r.K. i ... 



Ti.v '.r :::* rv . x: iiziii,' .i::on:s ;:':vrr '.vitliotlirr tho <amv prixhirts 
ft- *A :*h a!:- 1. i. I: - •:.:•:- ».rli'. r h- -ir. pi»*:-ii . .-i ro plaiinuiii-blaok, 
i.Tii": li t;.k'- j: - •, rii; i •.vK* n ■■: rV--^- -ir. p- r»r'.- ail" we* 1 to t-vajMj- 
r:^.- ::i :i b-:.'ik':r-_li-s : :;'i ri i: : 5|.iral of i "lit mum wire place J 
::!'■*>: iv T.liO hjiir i ' 'litiiiii'-s •• u'^'W. a ]>!i"sph«.«rtr>«:-fnt light 
b'.iii.' ii"tiO''l •-v-r III': vrirr iii tri-- ■i:trk ;is so<'!ias tIil- ^'low ceases 
H. I.)iivv . Wl^.rii MZ'-Liz- '1 •iX\\:in is !c.l into ether, each 
bubljli.- I Tijilii'*-.- u vi'.l»,iit P.-: -t: li. :iii«l a soluTiijii is thus ob- 
tain*:- 1 r'.'rit^iiniii,' r-xrili*; fui'l. '.«••■ io a' i^i, liV'.lri'.rfii ilioxidf. ami 
a small quaiitit.y •-f tniiiji'- a«i'l 'A. W. Wrii^'Iit". 

If ethor v;ip.iur l»'j p't.--;l «jVi-r ]uMti:«l ptitash, lime, or 
carbonate "f pMr-H-iuni, uiar.-li uas and livilrogeu are formed, 
but neither rH*ti«- :i'i'l n-T furniio a* i«l l>unias and Stas). 
This r«acti"ii i- ]iiol.iably ilu«- ti tii«- ]irrviuus f«.»rmation of 
}X)tassiuni aretnt-- a«'«'ordinu' t'» tliO »iju;in«'n : 

C.H.J ) -r '1 K( »H ^ H/) - iM '..H K( », - 4 H., 

and this ai ••tato is tlicn d«iMnip<>s*.d int • carbt-naie and marsh 
uas in the presence <»f alkali. 

222 fVx. — Ether is kir-tlv u>fd m the labomtorv ns well as 
in the arts and m:inufa'ture.s n-: a polwiu, f^r the prej)aration 
of 4*olKKlion, the extract inu nf tannic acid. \*c. Fmni its <:jreat 
volatility it has also I i-en usi-d in the manufacture of 'ww If 
bn.night in the form uf a tinr spray upon tlic skin it produces 
such a degree of cold a-^ to in»luie cotuplt'te in^^rnsibihty, anil 
LȣSice the employn\ent of the ether-spray has been projnjsed 
5 r effevlins; lo.^al ana-sthosia. 

^Ler va|¥>\ir when inlialnl jiroduci-s simil:ir etVccts to nitn»us 

* Fjl*nmever ami Tm Inpi"'. /■ /'>■•/.. c'A. «». I *»•;<. \\{'\. 



DECOMPOSITIONS AND USES OF ETHER. 537 



oxide. This appears to have been first observed in 1818 by 
Faraday who was investigating the subject. The introduction 
of ether as a general anaesthetic agent is due to Dr. C. Long of 
the United States in 1842. He did not however publish any- 
thing until three years later, when two dentists, Messrs. Morton 
and Jackson, made independent observations on the subject, and 
suggested the employment of ether for this purpose* The 
inhalation of ether was soon widely adopted in medicine. In 
Europe Sir James Simpson of Edinburgh was especially active 
in its introduction, and he showed that this body under certain 
conditions might be employed without any danger, especially in 
obstetric cases. The employment of this and other anaesthetics 
met with much opposition from a certain class of persons, but 
all such objections were successfully overcome by Simpson's 
energy and determination. 

223 Ether unites with bromine to form the compound 2C^HjqO 
+ 6 Br, when the two liquids are brought together in the cold. 
This compound is a crystalline mass somewhat resembling 
chromium trioxide, possessing a strong smell, and being decom- 
posed by water into its constituents. It is a very unstable 
compound, and on standing decomposes spontaneously with 
formation of water, hydrobromic acid, ethyl bromide, tribromal- 
dehyde, C2HBr30, &c.^ Various metallic chlorides and bromides 
also form compounds with ether. One of the first of these was 
obtained by Kuhlmann by bringing together anhydrous ether 
and stannic chloride. It forms a feathery crystalline mass of 
the composition 2 C^Hi^O + SnCl^, which distils at 80**, yielding 
glistening rhombic tables which are decomposed by water.* 
Various other compounds of ether with metallic chlorides and 
bromides have been obtained by Nicklfes.^ These are mostly 
crystalline, and some are volatile without decomposition, as for 
instance AlgBr^ + 2 C^HjqO, which sublimes in yellow needles. 
The trichloride and tribromide of antimony and of arsenic form 
similar compounds. Ether combines with antimony penta- 
chloride to form a greyish white crystalline mass, SbClg + C^Hj^O, 
a very unstable compound.* With titanium chloride it also 
forms the body TiCl^ + G^-^qO, crystallizing in small yellow 
tables melting at 42*^ to 45°, and boiling at 118" to 120.** Ether 

^ Schutzenberger, Compt. Bend. Ixxi^lSll. 

' Lewy, Canipt. Rend, xxi. 371. 

» Ann, Chim. Phys, [3], Ixii. 280 ; Campt. Rend, lii. 306; iTiii, 537 ; Ix. 800. 

* Williams, Joum, Chem. Soe^ 1876, ii. 468. 

VOL. III. Z 



338 THE ETHYL GROUP. 



al:^|^ cuiiiLincs >vitli vanadium oxychloride. By distilliog the 
produL-t under dimiuished pressure large steUated crystals 
having the formuhi C^H^^O + VOCl, are obtained, appearing 
redJish-hrowu by tnmsniitted but green by reflected light. 
Thoy melt below 100^ and are decomposed by water into ether, 
hydrochloric acid, and vanadium pentozide.^ 



Chlorine SrBSTrruTioy-PEODUCTS of Ether. 

224 Clilorino acts violently upon ether. If a few grams of 
othiT b? jKMirod into a flask filled with chlorine gas white fumes 
aro after some time given off, and then an explosion takes place, 
M» ^N^m|uni«.'J by tlame and considerable deposition of charcoal 
{ 'mik>h:r.;k\ If chlorine gas be led into ether, every bubble 
M t-i lire t«^ the ithor. which becomes heated throughout, and is 
nlniu.»tt'i\ *vn\ erte^l into a black tany mass. If, however, chlorine 
|i.. iM.M\l. v>iH vi.r.ly in the dark, into ether, very well cooled, 
1. ,. u ur..M\ i^v, il;;^''s arc f^Tnu-d. These have been investigated 
U^ I '.M K.i:nault/ Malaguli/ Lichen,^ Abeljanz,* and 

■*', ' . .V : ; ir:.,V or MomKhlorcthcr, C.HoClO. This, 

, ,,, .1 ^, .^^s^u. is the first pro^luct of the reaction, and 

"'.|\„.. ,1 ^^^^\^ ^\w .vmivunds which FrapolU and Wurtz» 

\ \^ ,, \y ..1m »iu, ,i 1^\ :i»c a.iiou of hydrochloric acid on a 
[\\,,[, , ,1.. U.S. /i,,.V./.a:Kl:.LK!.yae, and which they believed 

I", , ...J 1 ..»,!„ :»:;rrsubs:ancv with ethyl chloride. It 

,, , i, »,,.n iU '^ i." '.^S.x\hioh is decomi»sed by sulphuric 

,',! ,.,,u i. ,.i .. .1 V;,iJ.xdc. Imlnvhloric acid, and ethyl 

^^, I,,,,, ., 1 1 ^^\..l■^ yx u\x s^sliv.m othvLue it yields acetal, 
J ,1 '» ll^»n II ., U...U ,i.-.M?lva undiT the ethidene com- 
.,.^,,,1. II,. .. »,.».*!. n.u A m.u.vl;lorothyl oxide as well as 
„.n,,.i. .1 I. r...ui /..^!;xa.^^U;i.'h is ethidene oxide, is 

\\\'\ I u»M ji, f I III no - ^ll,^llO^ ^_ ,1^, 






CHLORINE SUBSTITUTION-PRODUCTS OF ETHKR B30 



Dicldor-Ethyl Oxhide, C^HgClgO. For tho preparation of this 
compound Lieben recommends that chlorine should be passed 
into ether cooled to 0** and the temperature giadually allowed 
to rise to 20^ It is then distilled off on the water-bath and the 
distillate again treated with chloriDe. By repeating these 
operations, the above compound is at last obtained as a strongly 
smelling liquid which boils with decomposition at 140** to 145** 
and has a specific gravity of 1*174 at 23° and burns on ignition 
with a luminous green-mantled flame. By the moderate action 
of zinc ethyl on dichlorinated ether, ethyl chlorinated ether, 
C^HgCl(C2H5)0, is obtained. This possesses a pleasant ethereal 
smell, boils at 141**, and has a specific gravity of 0*9735 at 0^ 
Heated with an excess of concentrated hydriodic acid in closed 
tubes to 100** it forms ethyl iodide and secondary butyl iodide. 
The formation of this compound shows that substitution has 
not taken place in both of the ethyl groups, as was originally 
supposed ; and Lieben explains this by the following equations : 

CjHgClCC^I^) I o + 2 HI = CgHjCKCgHJI + C^H^I + lip. 

C3H3C1(C,H,)I + HI = C,H3C1(C2H,)H + I,. 
C2H3C1(C2H5)H + HI = C2H,(C.H5)I -t HCl. 

By the further action of zinc ethyl on ethyl chlorinated ether 

or more simply if iodide of ethyl and zinc be heated with it^ 

the so-called di-ethyl ether, C^H3(C2H5)20.C2H5, is obtained, a 

body which boils at 131** and is a compound ethyl hexyl ether, 

yielding, on heating with hydriodic acid, ethyl iodide and 

secondary hexyl iodide. By the action of sodium ethylate 

on dichlorinated ether, etliTjl-ojcide-chlorinatcd-ethcr is formed. 

This is identical in composition with monochloracetal, CHgCl. 

CH(OC2H5)2, and for this reason dichlorinated ether" must 

.1 •■• GHoCrCHCl ) r\ 

possess the composition ^ (Ml i 

TricMor-Ethyl Oxide, C^HyCljO, is not known in the pure 
state. If the residue boiling above 153** obtained in the pre- 
paration of dichlorinated ether be heated with sodium ethylate 
it dissolves, and from the product of the reaction dichloracetal, 
CHClyCHCOC^Hg),, separates out, and hence it would appear 
that a trichlorinated ether exists having the composition 
CHCUCHCl ) ^ 

z 2 



340 THE ETHYL GROUP. 



Tetrachlor-Ethyl Oxide, C^H^Cl^O. This body was discovered 
by Malaguti, and first termed chlorinated ether and afterwaids 
bichlorinated ether. It is formed by the continued action of 
chlorine upon ether, when the liquid is gradually heated to 100'. 
The chlorine is absorbed quickly to begin with, then, however, 
a stormy evolution of hydrochloric acid takes place, so that the 
liquid requires to be cooled. After this chlorine is again led in, 
and then the whole heated to 140** until the mass begins to 
blacken. It is then mixed with water, dried in a vacuum over 
lime and sulphuric acid, and thus a thick liquid is obtained 
which has a pungent smell and a specific gravity of 1 5. It has 
no constant boiling point, but decomposes when heated. Alco- 
holic potash yields acetic acid together with other products, 
and on heating with sulphuric acid, trichloraldehyde or chloral, 
CCI3.CHO, is formed, and from this it appears that Malaguti s 
chlorinated ether is a mixture which contains the compound 

This latter body was first prepared in the pure state by 
L. Henry,* by the action of phosphorus pentachloride on the 
so-called chloral alcoholate (see Ethidene Compounds) : 

CC1,CH(0H) J Q ^ p(,,^ ^ CCI3.CHCI I Q ^ pQ(.,^ ^ jj(,j 

The same compound is likewise formed when chlorine is 
allowed to act on the monochlorinated ether obtained from 
aldehyde.^ It boils at 188"* to IOC*', possesses a specific gravity 
at 15** of 1*4211, and has a sweetish-bitter taste and a pungent 
camphor-like smell. 

rcntachlor-Ethyl Oxide, C^HgClgO, is obtained, according to 
Jacobsen, by the further action of chlorine on Malaguti's com- 
pound. It is a thick liquid having a specific gravity of 1*645, 
which is probably, however, a mixture. It gives ethyl com- 
pounds by various reactions, and probably, therefore, contains the 
compound C2Cl5(CjH5)0. This latter compound is also obtained 
from the last described tetrachlorinated ether ; by the action of 
alcoholic potash the compound CCij = CCLOCjHg is produced, 
and this unites with chlorine directly to form pentachlorinated 
ether, a liquid boiling at 190"* — 210** with partial decomposition 
being obtained. 

* Ber, Deuisch. Chim. Gts. iv. 101. 435; vii. 762; Comptfs Rendut^ xlvil 418. 

* Vogt and Wurtz, Comp. Reml Ixxiv. 777. 



CHLORINATED ETHER. 341 



The bromine compound, CCloBr.jCClBr.O.CgHg, is obtained 
as a colourless, heavy liquid having a pleasant smell, by the 
action of bromine on the latter body, and this on cooling crys- 
tallizes in large clear crystals, which melt at IT*} An isomeric 
pentachlorinated ether was obtained by Henry * by acting with 
phosphorus pentachloride on a compound also belonging to the 
ethidene series obtained by the union of chloral and ethylene 
chlorhydrate (monochlorethyl alcohol). 

This latter compound corresponds to the above-mentioned 
chloral alcoholate. 

This pentachlorinated ether is a colourless, thick liquid, pos- 
sessing a sweetish taste and a strong camphor-like smell. It 

possesses the constitution pyT pi prj \ 0. 

Fcrchiarinated Ether, C^ClioO, is the last product of the action 
of chlorine on ethyl oxide, and is formed only in the sunlight. 
It is a solid body, possessing a penetrating camphor-like smell, 
and crystallizes from alcohol in orthorhombic crystals which 
melt at 69", and have a specific gravity of 1*9. In its pre- 
paration, hexchlorethane, Cg^l^,, and trichloracetyl chloride, 
CCljj.COCl, are usually formed, and the perchlorinated ether 
decomposes completely into these compounds on heating to 300^ 
By the action of an alcoholic solution of potassium sulphide^ a 
compound is formed termed by Malaguti chloroxcthosc : 

cSy0 + 2K,S=gg}0 + 4KCH-S, 

This is a liquid boiling at 210°, which unites with chlorine 
in the sunlight to form perchlorinated ether, and with bromine 
to yield the compound C^doBr^O. If chlorine be allowed to act 
in presence of water on chloroxethose, trichloracetic acid is 
formed as follows : 

CCr=CCl } O + 2 Cl. + 3 HOH = 2 CCI3.CO.OH + 4 HCl. 

CH I . . . 

Mcthyl'Etlujl'Ether, p t| > 0, is a liquid possessing a smell 

resembling that of ethyl oxide, and boiling at 11*. It is best 
obtained by the action of ethyl iodide on sodium methylate. 
This compound is also produced by treating sodium ethylate 
with methyl iodide (Williamson), and it was originally termed 

* Busch, Ber. Ikutsch, Chem. Gca, xi. 445. * Ih. vii. 762. 



342 THE ETHYL GROUP. 



by Lim the three-carbon ether. It may also be obtained by 
distilling together potassium ethyl sulphate and potassium 
methylate,^ and by the action of dry silver oxide on a mixture 
of the iodides of ethyl aud methyl (Wurtz). 



THE ETHEREAL SALTS OP ETHYL, 
OR ETHYL COMPOUND ETHERS. 

Ethyl Chloride, C^H^Cl. 

225 This compound was first obtained in alcoholic solution by 
Basil Valentioe, who thus describes its preparation : ^ " This I 
also say that, when the spirit of common salt unites with spirit 
of wine, and is distilled three times, it becomes sweet, and loses 
its sharpness.*' In his Last Testament he also says :* "Take of 
good spirit of salt which has been well dephlegmated and 
contains no watery particles one part ; pour to this, half a part 
of the best and most concentrated spiritus vini which also 
contains no phlegma or vegetable mercury." He goes on to 
state that this mixture must be repeatedly distilled, and then 
"placed in a well-closed bottle, and allowed to stand for a 
month or until it has all become quite sweet, and has lost its 
acid taste. Thus is the spirit us salts et vini prepared, and may 
be readily extracted." 

The mixture thus obtained of alcohol and ethyl chloride, or 
sweet spirit of salt, was well known to the later chemists. 
Thus Glauber speaks of it in 1648 in describing strong hydro- 
chloric acid : " When dephlegmated spirit of wine is poured 
into such strong spirit of salt and digested for a long time, the 
spirit of wine makes a separation and kills its sal volatxU, bo 
that a fine clear oleum vini swims on the top, which is not the 
least potent of the cordials." 

Pott then showed in 1730 that this sweet spirit of salt could 
bo obtained by the action of butter of arsenic or butter of 
antimony on 8i)irit of wine, and other chemists found that 
other metallic chlorides may be employed for the like purpose. 
Ludolf, in his work on Medical Chcmistnj, states in 1749, that 
on heating spirit of wine with sulphuric acid and common salt a 
distillate is obtained which when treated with lime yields an ether, 

* C-hancc1, Conij>f. Jir,id. xxxi. 621. 

• Winirrftnhtn^ ilrn 7rf»*w« Sf*'inji drr urtiftrn /fV /V/i, cJ. Petracus, p. 72. 
' Sasilius J'ulciitinHs, ed. Petracus p. 73'». 



THE ETHEREAL SALTS. 343 



but ho vainly endeavoured to obtain a similar compound by the 
action of muriatic gas on spirit of wine. Beaum^'s experiments 
in this direction also did not succeed, but Woulfe * obtained 
hydrochloric ether in this way, and it was afterwards prepared 
and sold by an apothecary in Germany and known as Bassets 
hydrochloric ether. This same compound was afterwards termed 
light liydrochloric ether, in order to distinguish it from the 
BO-called heavy hydrochloric ether obtained by heating alcohol 
with common salt, manganese dioxide, and oil of vitriol. This 
latter body, which was prepared in 1782 by Westrumb, and after- 
wards observed by Scheele, is however a mixture of various 
oxidation-products. 

Colin and Robiquet- were the first to point out the true 
composition of ethyl chloride. The above-mentioned method 
of distillation has been used until recently in order to obtain 
this compound, although it is not in every respect satisfactory. 
Boullay found that, when obtained by means of common salt 
and sulphuric acid, the product usually contains a small quantity 
of ethyl oxide. 

Pure ethyl chloride is" prepared by passing hydrochloric acid 
gas into strong spirit of wine. The saturated solution is allowed 
to stand for some time, and then distilled oflf on a water-bath. 
The yield is, however, not more under the most favourable 
circumstances than corresponds to 15 per cent, of the alcohol 
employed. The alcohol may, as Groves^ has shown, be com- 
pletely converted into the chloride, if zinc chloride be added 
and hydrochloric acid gas passed into the boiling solution; this 
gas is then completely absorbed, and when the liquid has 
become saturated, pure ethyl chloride is evolved, the reaction 
going on until the whole of the alcohol has been converted. 

According to the experiments of Krllger,* ether is likewise 
formed in this process when the mixture is heated to begin 
with. This can be avoided by saturating the solution of one 
part of zinc chloride, and 82 parts of spirit with hydrochloric 
acid in the cold, and then heating to the boiling-point, the 
gas being passed in so long as ethyl chloride is formed. The 
evolution-flask must, of coui-se, be connected with an inverted 
condenser in order to retain the alcohol vapour, whilst the more 
volatile chloride of ethyl passes into a vessel surrounded either 
with ice or a freezing mixture, where it is condensed. In this 

* Phil Trans. 1767, p. 520. • Ann. Chim. Phys. i. 848. 

* Joum, Chcm, Soc, 1874, 636. ** Joum. Prakt. Chein. [2], xiv. 193. 



344 THE ETHYL GROUP. 



^ay it is easy to obtain a kilogram of the compound in a few 
hours, and this method serves admirably as a lecture illustration. 
The action of hydrochloric acid on alcohol is explained by the 
following equation : 

CgHg.OH + HCl = CaH^Cl + H^O. 

Hence the conclusion that zinc chloride simply acts as a strong 
hygroscopic agent would not appear improbable, but this is not 
the case, inasmuch as it cannot be replaced by other equally 
efficacious hygroscopic agents such as chloride of calcium or 
sulphuric acid. Its peculiar action depends upon the fact that 
the alcohols very easily decompose, with elimination of water, into 
the defines, that is the hydrocarbons of the series CjfH2n, which 
unite with hydrochloric acid to form the monochlorides. Accord- 
ingly, in the preparation of ethyl chloride according to Groves s 
method two reactions take place ; one part is produced by the 
direct action of hydrochloric acid on alcohol, and the other part 
by the union of ethylene in the nascent condition with hydro- 
chloric acid. The truth of this explanation is proved by the 
fact that when amyl alcohol is thus treated, a considerable 
quantity of the s^coudary chloride is found, together with the 
primary chloride, and this, as we know, can only be obtained 
from the olefine amylene CgHj^,. * 

Ethyl chloride is also formed by the action of phosphorus 
pentachlorido on alcohol (Wurtz), and, together with other 
products, when alcohol is treated with chlorine, and this accounts 
for the production of this substance in considerable quantity 
in the manufacture of chloral. 

226 Fropcrtics, — Ethyl chloride is a colourless mobile liquid 
having a peculiar and pleasant odour, and a sweetish, burning 
taste. It does not solidify at — 29°, boils at 12°*5 (Regnault), at 0* 
possesses a specific gravity of 0*9214 (Pierre) and its vapour density 
is 2*219 (Thenaid).* It is but slightly soluble in water, though 
dissolving readily in alcohol, strong spirit taking up half its weight. 
This solution may easily be kept in well-stoppered bottles, and 
chloride of ethyl may readily be separated out from such a 
solution by gently warming it and freeing the gas from alcohol 
vapour by passing it through sulphuric acid (Groves). 

Ethyl chloride is easily combustible, burning with a luminous 
green-mantled flame. When its vapour is passed over heated 

* Seborlemmer, Joum, Chtm. Soc, 1875, 808. • Ann, Chim, Ixiii. 49. 



ETHYL CHLOniDE. 345 

80<j&-liine, oleEaQt gas is formed, according to Stas, whilst 
h. Meyer ' finds that in this reaction a mixture of hydrogen 
and marsh gas is obtained together with sodium acetate and 
carbonate : 

(«) C.H5CI + 2 KOH = C2H3KO, + KCH- 2 Hy 
(i) C»HjKO, + KOH = KjCO, + CH.. 




Substitution-products are formed by the action of chlorine on 
ethyl chloride. Tbese will be described hereafter. 

Tho appamtus shown in Fig. 88 serves to exhibit, in the case 
'-,<itit. Chem. Fham. ciisix. 28B. 



S40 THE ETHYL GEOCP. 



of ethyl chloride, the passage from the liquid to the gaseous 
state, and rice rtrtd.^ In order to liqaefy the gas contained in 
the shorter and stoppered limb of the syphon tube, mercuiy 
must be poured into the longer limb and the compressed gas 
cooled by pouring some ether over the shorter limb. On allow- 
ing the temperature to rise, and on permitting the mercuiy to 
run out by the lower stop-cock, the liquid will be seen to boil, 
and the whole again assume the gaseous condition. 

227 Ethyl Bromide, C^H^Br, was first prepared by SeruUas' in 
1827 by gradually adding bromine to a miicture of alcohol and 
phcsphorus. It is also formed, together with other products, 
by the action of bromine on absolute alcohol (Lowig), as well as 
by heating spirit of wine with strong hydrobromic acid and by 
various other reactions. In order to prepare it, Personne's* 
method is probably the best. For this purpose 40 parts of 
amorphous phosphorus and IGO parts of absolute alcohol are 
brought into a flask connected with a reversed condenser, and 
gradually 100 parts of bromine allowed to flow in, the flask 
being first well cooled in order to moderate the violenoe of the 
reaction. As soon as this has been added, the mixture is 
distilied on a water-bath, the distillate being shaken up with 
water and the bromide which separates out being then dried 
over chloride of calcium or potassium carbonate and afterwards 
purified by distillation. 

Ethyl bromide is a liquid resembling the chloride in its 
smell and taste, boiling at 38°'37 (Regnault), and having at 0** 
a specific gravity of 1*4733 (Pierre), whilst at 15** it is 1*4189 
(Mendolc jeff;. Its vapour density was ascertained by Marchand * 
to 1)0 3 754. It bums, when ignited, with a fine green smoke- 
less flame, evolving vapours of bromine. 

228 Ethyl Iodide, CgH^I, was discovered by Gay-Lussac* 
in 1815, and is formed by heating together spirit of wine and 
hydriodic acid, as well as by the simultaneous action of iodine 
and phosphorus on alcohol ^ (Serullas) : 

5 CjH/JH + 5 1 + P = 5 G,H,I + H^PO^ + H,0. 

This last reaction is now always employed for the preparation 
of this import!int substance. It is largely used in the arts and 

* Hofmftnn, Der. Dentwh. Chem, Ge», xii. 1123. 

■ Ann. Chim. Phftn. xxxiv. 99. ' Cmnpt. lUnd, Hi. 468. 

* Joum, Pntki. t'hrm, xxxiii. 186. * Ann.Chim, Phys. xcL 89. 

* /»«JUY. 3*23; xlii. 119. 



ETHYL BROMIDE. 347 



manufactures, and for the preparation of other ethyl compounds. 
Formerly, of course, common phosphorus was employed, and 
a number of receipts were given for this purpose. In all of 
these, precautions had to be taken to avoid explosions due to the 
violence of the reaction, and to prevent loss of substance. 

Personne ' was the first to suggest the employment of 
amorphous phosphorus, and Beilstein and Rieth,^ who especially 
worked out this method, found the following proportions to be 
the best. Ten parts of red phosphorus and 50 parts of spirit 
are brought into a tubulated retort connected with a Liebig'a 
condenser, and to these 100 parts of iodine are gradually added. 
After standing for 24 hours, the ethyl iodide is distilled oflF. Of 
course the iodine and spirit may be mixed to begin with, and 
the phosphorus then added from time to time, and in this case 
G7 parts of this latter body are sufficient. The distillate is 
washed with dilute caustic soda and water, and the iodide of ethyl 
which separates dried over calcium chloride. The residue in 
the retort consists chiefly of ethyl phosphoric acid, and, for this 
reason, an excess of alcohol, as is shown in the above pro- 
portions, must be used. 

Ethyl iodide is also formed when potassium iodide is distilled 
with a saturated solution of hydrochloric acid in spirit of wine,* 
or when concentrated hydriodic acid is heated under pressure 
together with ethyl chloride.* Another remarkable reaction 
is its formation on heating ethyl nitrate with potassium iodide.* 

Ethyl iodide is a colourless, strongly refracting liquid, possess- 
ing a peculiar ethereal and somewhat pleasant smell, boiling at 
71**'3 (Andrews), or at 7l"'6 (Frankland). Its specific gravity at 
0° is 1-9755 (Pierre), and at 15", 1-9309 (Mendelejeflf) ; whilst 
its vapour density was found by Marchand to be 5'417. Ethyl 
iodide is almost insoluble in water, but is miscible with alcohol 
and ether. It is only difficultly inflammable, burning with evolu- 
tion of iodine vapours. When heated with fifteen times its 
weight of water to 100^ it gradually dissolves with formation of 
alcohol. Chlorine decomposes it with formation of ethyl chloride 
and separation of iodine, and, like many other organic iodides, 
it is also decomposed when exposed to the action of light, iodine 
being set free and the liquid becoming gradually red and after- 
wards brown. This decomposition takes place especially quickly 

* Compt. Rend. lii. 468. ' Ann. Chem. Pharm. cxxvi. 250. 

' De Vrij, Joum. PJunvrn. xxxi. ir>9. * Lichen, Zri/sr/i, Chcm, 1868, 712. 

• Jnucadella, Cmnpt. Rend, xlviii. 315. 



ETHYL IODIDE. 349 



231 Ethyl Sulphite, (CgHJoSOg, was first prepared by Ebelmen 
and Bouquet^ in 1845 by acting on absolute alcohol with 
sulphur monochloride. It is also formed when thionyl chloride is 
brought in contact with alcohol.- For the purpose of preparing 
this substance, an excess of absolute alcohol is added to well- 
cooled chloride of sulphur or thionyl chloride, the product being 
purified by fractional distillation. Its formation* from thionyl 
chloride is explained by the equation : 

SO { cl + 2 HO.C2H, = SO I ^g^Hs ^ 2 HCI. 

When alcohol is treated with chloride of sulphur, thionyl 
chloride appears to be first produced, and this acts again on the 
ethyl hydrosulphide formed at the same time : 

(1) S,Clj + HO.C.Hj = SOClj + HS.C2H5. 

(2) 3 SOCU + 4 HS.CjH5 = SOCOaHj)^ + 2 C^H^Cl + 4 HCI 

+ 2Sj. 

According to this reaction the sulphur monochloride may be 
regarded as a sulpho-thionyl chloride (Carius). 

Ethyl sulphite is a mobile liquid which smells of peppermint, 
and has at first a cooling but afterwards a burning sulphurous 
taste. It has a vapour density of 478 (Ebelmen and Bouquet) 
and a specific gravity of I'lOGS at 0°, and boils at ICl^'-S.^ It 
is combustible Avith diflSculty, and can be inflamed only when it 
has been previously warmed. 

Ethyl Sulphurous Acid, H(C2H5)S03, is not known in the 
free state, and of its salts, potassium ethyl sulphite is the only 
one which has been prepared. This is formed when a solution 
of caustic potash in five parts of water is gradually added to well- 
cooled ethyl sulphite, so that the liquid always remains colour- 
less. The mixture is then allowed to stand until the whole of 
the ethyl sulphite is dissolved, and the solution next saturated with 
carbon dioxide and the whole allowed to evaporate in a vacuum. 
The residue is dissolved in 90 per cent, spirit, this evaporated, 
and the residual salt crystallized from boiling absolute alcohol. 
It forms delicate silky glistening crystals easily soluble in water. 
The yield is only small, as the body is very readily decomposed, 

' Ann. Chim, Phys, [3], xvii. 06, 
' Carius, Ann, Chem. Pharm. cxi. S3. 
3 Carius, Journ, Prakt. Chem, [2], ii. 285. 



360 THE ETUYL GROUP. 



and much potassium sulphate is formed during its preparation. 
Freshly prepared, it is odourless, but after some time it acquires 
the smell of ethyl sulphite, and the aqueous solution contains 
potassium sulphate.^ 

Hydrogen Ethyl Sulphate or Ethyl Sulphuric Acid 

H(C,HJSO,. 

232 The calcium and barium salts of this acid were obtained 
in 1802 by Dabit from the residues of the preparation of ether. 
These were, however, regarded as salts of an acid having 
a composition intermediate between sulphurous and sulphuric 
acids. These observations remained unnoticed until 1819, when 
Sertlimer remarked, from experiments made in 1806, tliat spirit 
of wine unites with sulphuric acid, forming a compound to 
which he gave the name of sulphovinic acid. He showed more- 
over that other acids were also able to form similar vinic acids. 
Vogel,^ in 1819, then investigated sulphovinic acid and its salts 
more accurately, and came to the conclusion that the acid pre- 
pared by Sertumer's method may be considered as a compound 
of hyposulphuric acid with a heavy ethereal oil, and is identical 
with Dabit's acid. Gay-Lussac, in 1820, came to the same 
conclusion, and so indeed did BouUay and Dumas, whilst 
Hennell looked upon it as a compound of sulphuric acid 
with a hydrocarbon, having the composition of olefiaiit gas. 

In 1828 SeruUas proved that the compound might be re- 
garded as an acid sulphuric ether, and its salts as compounds of 
sulphates with the then unknown normal ethyl sulphate. This 
view was adopted by the supporters of the radical theory, by 
whom ethyl sulphuric acid was considered as a compound 
analogous to bisulphate of potash containing as its constituents 
sulphuric acid and neutral sulphate of ethyl oxide : 

KO.SO^-\-nO,SO^. 
KO.SO.^ + C^ff^O,SO^. 

Preparation. — In order to prepare ethyl sulphuric acid, con- 
centrated oil of vitriol is quickly but carefully mixed with 
strong alcohol, and the mixture heated for some time on a 
water-bath : 

SO, 1 2 + C,H,.OH = SO, I J? j^ + H,0. 

» Warlitx, Ana. Chem. Pharm, cxliii. 72. • Gill. Ann. Ixiii. 81. 



ETHYL-SULPHURIC ACID. 351 

The product always contains free sulphuric acid and unaltered 
alcohol, both when equal molecules are employed or when an 
excess of either compound is used, and even if the hcatin::^ be 
carried on for any length of time. Hennell,^ who used equal 
parts by weight of alcohol of specific gravity of 0*82 and oil of 
vitriol, found that 56 per cent, of the latter is converted into 
ethyl sulphuric acid. Berthelot,* in mixing equal molecules of 
acid and alcohol of 94 per cent, strength, obtained the following 
yields : 

After 40 hours 56 per cent. 

„ 90 „ 57-4 

„ 20 days 59 „ 

„ 147 „ 58 8 



When alcohol containing 20*7 per cent, of water was employed, 
the production of the acid weot on much more slowly, and after 
a lapse of 147 days the liquid contained only 54 8 per cent, of 
ethyl sulphuric acid. Oa the other hand, by using absolute 
alcohol, the yield can, according to Claesson,' be raised to 77'4 
per cent. This last-named chemist heated a mixture of alcohol 
and pure sulphuric acid on the water-bath, and employing, to 
one molecule of acid, varying quantities of alcohol, expressed in 
molecules, obtained to 100 parts of sulphuric acid the yields as 
noted below : 

0-5 1 1-5 2 2-5 8 4 

731 571 596 65 72 77*4 774. 

From this it appears that, when equal molecules of acid and 
alcohol are employed, 57 1 per cent, of ethyl sulphuric acid is 
formed. This yield increases, however, with an increase in 
the quantity either of acid or of alcohol. 

Ethyl sulphuric acid is also formed when sulphuric acid, 
warmed on a water-bath, is saturated with ether vapour : 

2 SO, { g 4- (C,R^f> ^ - SO, { ^ jj -f- H,0. 

In order to prepare ethyl sulphuric acid from the product 
obtained by one or other of these reactions, the mixture is 
allowed to cool completely, then several times its volume of 
water is added, and the whole is neutralized with barium 

* Phil. Trans, 1828, ii. 365. ' Bull. Soc. aiim. xix. 227. 

" Joum. Prakt, Chem. [2], xix. 246. 



352 THE ETHYL GROUP. 



carbonate or white-lead. In all these operations a rise of tem- 
perature must, as much as possible, be avoided. The soluiioii 
of the barium salt is then carefully acted upon with the requisite 
quantity of sulphuric acid, or the lead salt is decomposed with 
sulphuretted hydrogen, and the filtered liquid evaporated in a 
vacuum over sulphuric acid. A colourless, oily, very acid liquid 
.is thus obtained which has a specific gravity of 1*035 to 
1*037. This is insoluble in ether, and is decomposed on long 
continued exposure to sulphuric acid in a vacuum. On heating 
a little ether is given off (Hennell, Sertiirner). This is explained 
by the fact that the acid cannot be obtained quite anhydrous, 
inasmuch as some alcohol is formed, and this acts in the usual 
way on the ethyl sulphuric acid. 

Its dilute aqueous solution decomposes slowly on standing, 
and quickly when warmed or boiled, into sulphuric acid and 
alcohol. 

Anhydrous ethyl sulphuric acid is obtained, according to 
Claesson, by slowly dropping chlorsulphonic acid into well- 
cooled alcohol. Like the corresponding methyl compound, it is 
an oily liquid which does not adhere to the suiface of glass. 

The Ethyl Sulphates. 

233 Ethyl sulphuric acid is a monobasic acid forming a series 
of salts, all of which are soluble in water, and usually crystallize 
well. Some are very stable compounds, whilst others decom- 
pose on standing. Their dilute solutions can be boiled without 
decomposition, but in concentrated solution they decompose with 
formation of alcohol, sulphuric acid, and a sulphate. This 
decomposition does not take place in the cases of the salts of 
the alkalis or alkaline earths, provided an excess of alkali be 
present. 

Potassium Ethyl Sulphate, K,{Cfi^^O^, is obtained from 
the barium or calcium salt by double decomposition with 
potassium carbonate. It is usually obtained in tablets closely 
resembling those of boric acid, but when slowly crystallized, it 
yields large transparent monoclinic tables. At 17** it dissolves 
in 8 part of water. It is also soluble in spirit, but not m 
absolute alcohol, and deliquesces on exposure to moist air 
When fused with caustic potash, alcohol is formed, and, on 
heating with dilute sulphuric acid, ether is produced. This 
salt is frc([uently employed for the preparation of other ethyl 



THE ETHYL SULPHATES. 353 



compounds, because this, as well as other ethyl sulphates, when 
heated with salts of other acids, yields a new ethereal salt by 
replacement of the metal by ethyl. 

Sodium Ethyl Sulphate, Na(C2H5)SO^ 4- HgO, is formed as 
a cauliflower-like deliquescent mass, which is soluble in alcohol. 

Amraonium Ethyl Sulphate is easily soluble in water, alcohol, 
and ether, depositing from solution in lar^e, colourless, deli- 
quescent crystals, which fuse without decomposition at G2°. 

Calcium Ethyl Sulp)iate, (^di(fl^\i^^O^\ + 2H2O, is obtained 
by saturating crude ethyl sulphuric acid with chalk. The 
solution thus obtained, which contains gypsum, may be con- 
veniently used for the preparation of the foregoing salts. It 
crystallizes in tablets, and also in transparent monoclinic crystals, 
which are unalterable in the air and easily soluble in water. 

Barium Ethyl Sulphate, ^di{G,^^0^^-\-2Hfi, is isomorphous 
with the calcium salt, and crystallizes in colourless glistening 
tables or prisms, which dissolve at VJ"" in 0*92 part of water, 
and is also soluble in spirit, but not in absolute alcohol, which 
on boiling removes from the salt one molecule of water. 

Lead Ethyl Sulphate, Pb(C.,H5S0J., -f- 2H.3O, crystallizes in 
large colourless tables, soluble in water and spirit. These lose 
water easily, and decompose slowly on keeping, with formation 
of lead sulphate, sulphuric acid, ether, and ethyl sulphate, for 
which reason the salt attains a pleasant smell. When its 
solution is saturated with lead hydroxide, a liquid having a 
neutral reaction is obtained, and this on evaporation in a 
vacuum leaves a residue of a basic salt, (PbCgHgSOJgO, as an 
amorphous mass. This is much more permanent than the 
normal compound, although very hygroscopic and easily soluble 
in water. 

Silver Ethyl SulpJiate, Ag (05115)804 + HgO, forms small 
glistening tablets, readily soluble in spirit. 

Besides the compounds above described, various other ethyl 
sulphates are known. 

Normal Ethyl Sulphate, (C^H^gSO^. 

234 This compound was examined by chemists in the last 

century, but its nature has only quite recently been ascer- 

'tained. Formerly this ether was prepared by distilling spirit 

of wine with oil of vitriol. This operation was conducted 

in a retort heated in a sand-bath, and as soon as the ordinary 

VOL. HL A A 



354 THE ETHYL GROUP. 



ether had come over, the receiver was changed and normal 
ethyl sulphate, or, as it was termed, wine-oil or oleum vttrolii 
duke, collected. Concerning the formation and composition 
of this body, very different views were held. Towards the 
end of the last century it was generally assumed that wine- 
oil is ether rendered impure by the presence of a large 
quantity of sulphuric acid, for Wiegleb stated that common 
ether is obtained in large quantities when this substance is dis- 
tilled with caustic potash. In the year 1797 the difference 
between wine-oil and common ether was distinctly pointed out 
by Fourcroy and Vauquelin, who assumed that the first com- 
pound stood in the same relation to ether as ether does to 
alcohol. This view was generally adopted until Hennell, in 
1826, proved that the compound contains sulphuric acid, and 
that it is to be considered as a compound of this acid with 
carbon and hydrogen, in which the latter elements are present 
in the same relative quantities as in ether itself. He also 
showed that, when wine-oil is heated with water or with alkalis, 
sulphovinic acid is formed, whilst a liquid hydrocarbon is 
liberated. This in some cases crystallizes, and possesses the 
composition of olefiant gas. These facts were fully confirmed 
by the subsequent investigation of Sorullas,^ Marchand,^ and 
Liebig.' Serullas found that, when wine-oil undergoes distilla- 
tion, it yields the salts of ethyl sulphuric acid, and liebig 
gavo to it the formula (02115)2804 + C^HgSOj, and termed it 
sulphovinate of wine-oil. 

According to the recent experiments of Claesson,* wine-oil 
consists chiefly of ethyl sulphate, generally mixed with a larger 
or smaller quantity of the polymers of ethylene, a fact already 
observed by Hennell ; this latter chemist distinguishing 
between wine-oil, a liquid boiling at 280^ and etherin, a solid 
crystalline mass obtained when the wine-oil is allowed to stand 
for some days. 

The first attempt to obtain pure normal ethyl sulphate was 
made by Wetherill,* who passed the vapour of sulphur triozide 
into ether or alcohol He thus obtained a colourless liquid 
smelling like peppennint which decomposes on heating, and 

which, as Krlenmeyer afterwards showed, is a mixture of normal 

( OH 

ethyl sulphate and ethyl isothionate, C^H^ -j ^.^ p „ 

* Ann. Chitn. Phy.n. xxxix. ir»8. ■ Joum, Pmki. Ch^n, xr. 8. 

■ Poyg, Ann. xxi. 40. « Jaum, Pmki. Chfm. [2], xix. 265. 

* Ann, Chevi. Pttarm. Ixvi. 117. 



NOIIMAL ETHYL SULPHATE. '355 



Ethyl sulphate was first obtained iu the pure state by Claesson 
in acting on alcohol with ethyl chlorsulphouate, a body which 
will be described immediately. Ho also prepared it by the 
action of sulphuric acid on absolute alcohol. If ice and then 
water be added to the cold mixture and the liquid shaken up 
with chloroform, the sulphate is dissolved and left behind on 
evaporation. Ethyl sulphate is also formed when silver sulphate 
is heated with ethyl iodide to 150^^ Claesson obtaining a 
satisfactory yield in this way. 

Ethyl sulphate is a colourless liquid, insoluble in water, 
possessing a pleasant peppermint-like smell ; it boils at 208" 
with slight decomposition, but may be distilled unaltered under 
diminished pressure. At 19"* it possesses a specific gravity of 
11837. It is only very slowly decomposed by cold water, but 
boiling water decomposes it more or less quickly according to 
the amount present, alcohol and ethyl sulphuric acid being first 
formed. If ethyl sulphate be heated with alcohol, the following 
reaction takes place : ^ 

^^* t c.H, + rf r ' \ C2H5 + an, / ^• 

Hthyl CMorsulphonatc, CI.SO.2.OC2H5, was first prepared by 
Kuhlmann,^ and afterwards more carefully examined by William- 
son* and Purgold.* According to the latter chemist, the com- 
pound is an oily, strongly smelling liquid, which can be distilled 
in a vacuum. The same compound is obtained purer and more 
readily, as was found by Miiller,® by leading ethylene gas into 
chlorsulphonic acid. In order to purify the crude product, it is 
either distilled in a vacuum or mixed with ice-cold water and 
dried over anhydrous copper sulphate. The pure compound 
boils under ordinary pressure with slight decomposition at from 
151° to 154° (Claesson). It has a penetrating pungent smell, 
and acts very violently upon the eyes. When absolute alcohol 
is allowed slowly to run into this compound, a violent reaction 
occurs, which, according to Claesson, may be represented as 
taking place in two directions : 



* Stempnewsky, Bcr. JJcutsch, Chem. Ges. xi. 514. 
' Erlenmeyer, Ann. Chem. Pharm, clxii. 373. 

' Ann. Cfiem. Pharm. xxxiii. 108. 

* Quart. Jcum Chem. Soc. x, 97. 

* Ber. Deutsch. Clwm Gca. vi. 502. 

* Ikid. vi. 227. 

A A 2 



2SA THE ETHYL GROUP. 



'' ^'^ [S;,H, + ^'AOH = S0,{ gJ?H^+ C3.CL 

If alcohol bo added to ethyl chloreulphonate, ethyl chloride, 
hydrochloric a^nd, and a small quantity of ethyl ether is formed, 
and a considerable quantity of ethyl sulphate : 

^r { OC,H, + «0^'*H* = SO^ { 00:2: + HCL 

235 Jlydrogen Ethyl Srlemtc, H(C2HJSeO^ is formed when 
equal parts of spirit of wine and concentrated selenic acid arc 
heated together for some time to 100^ In order to purify the 
pHNlnct, it is diluted with an equal volume of water, neutralized 
with lead carbonate, and allowed to evaporate to one-half in a 
vacuum. Tlie greater portion of tlie lead is then thrown down 
in combination with selenic acid, and the rest precipitated as 
sulphide with sulphuretted hydrogen, and thus an aqueous, 
strongly acid liquid, containing ethyl selenic acid, is obtained. 
It very roa^lily decomposes, and forms a series of salts which are 
aUo very prone to decomposition.* 

Potasaium Ethyl Selenate, K(C2H5)SeO^ forms small talc-like 
tablets which possess a sweetish saline taste. 

Lead Ethyl Selenate also crystallizes in tablets, and is so 
unsUible that it has not been analyzed. If a solution of 
lead ethylsulphate be added to its solution and the mixture 
cvajKiratcd in a vacuum, tablets having the composition 

3 [Pb(C,H,SO,)j + 2 H,0] + 2 [Pb;C,H,SeOjj + 2 H,0] 
are dep^jsited. The normal ethyl selenate is not known. 



Ethyl Nitrite, C^HgNOg. 

236 Ruynioud Lully is generally said to have been the dis- 
coverer of this compound, which was formerly known as nitric 
ether, and it is certainly true that ho was acquainted with the 
violent action which nitric acid proiluces on alcohol, but in his 
process he allowed the ether to escape. Later chemists who speak 
of the ftjnritus nitri dulcis s.dnlcijicatus, understood by this term 
the residue which n.'mains behind after the reaction. Hugens 

* Faliinn, Ann. ('firm. Pharm. Suppl. i. 241. 



ETHYL NITRITE. 357 



and Papin^ showed that when alcohol and nitric acid are mixed 
together under the receiver of an air-pump, an elastic fluid 
is formed, Kunkel,^ however, was the first to observe that 
a liquid which swims on the surface of water may be obtained 
from such a mixture. This observation remained unnoticed, 
because the so-called nitric ether, largely used as a medicine, 
was obtained by distilling a considerable quantity of alcohol with 
a small quantity of nitric acid, and was, therefore, only obtained 
in dilute alcoholic solution. Navier, a physician at Chalons 
sur Mame, observed in 1742 the fact already noticed by Kunkel, 
namely, that an ethereal smell is perceived when nitric acid and 
spirit of wine are mixed together, and that when a mixture of 
equal volumes of these liquids is placed in a vessel and allowed 
to stand for ten days, an ethereal liquid swims on the top. 
This fact was communicated to the French Academy by Duhamel 
in the above year, and the liquid thus produced was believed to 
be closely allied with Frobenius's ether. 

Another method of preparing nitric ether which was after- 
wards largely employed, especially by Berzelius, was suggested 
by Black in 17C9. It consists in pouring nitric acid, water, and 
spirit of wine into a tall vessel, in alternate layers one above 
the other, when nitric ether is formed by the gradual mixture of 
the liquids. Tielebein, in 1782, stated that the best yield was 
obtained when the process of Navier was adhered to, and strong 
nitric acid and spirit of wine mixed in the cold, the vessel being 
quickly closed. This proposal gave rise to the publication of a 
great number of receipts on the best means of preparing nitric 
ether, all of which, however, depended on the alcohol being 
gradually added to nitric acid, and the separation of the nitric 
ether, which is formed, from the rest of the liquid either by 
pouring off or by distillation. 

The compound formed by this action of nitric acid on alcohol 
is, however, not ethyl nitrate as was formerly supposed, but 
ethyl nitrite, one part of the alcohol being oxidized, and the 
nitrogen trioxide, thus formed, combining with another part of 
the alcohol in the following way : 

2 C2H5OH + N2O3 = 2 C2H5NO2 + HgO. 

Ethyl nitrite thus obtained always contains oxidation-products 
of alcohol, especially aldehyde, and this turns alcoholic potash 
brown when shaken up with the liquid. 

* Phil, Trails, 1676 " FpUtola contra spiritu in vini siitr acido, 1681, 



ETUYL NITRATE. 369 



penetrating ethereal smell, resembling apples or Hungarian 
wine, and a peculiar pungent taste. It boils at 18^, and has 
a specific gravity of 0*900 at 15°5 and a vapour density of 2*627 
(Dumas and Boullay). When ignited in contact with air it 
bums with a bright white flame. The pure ether can be kept 
for many years without undergoing any change, but if impure, 
and especially if it contains water, it soon becomes acid and 
gradually evolves oxides of nitrogen in such quantities that the 
bottle containing it frequently bursts. Alkalis, especially in 
alcoholic solution, decompose it quickly, with fiarmation of 
alcohol. Ammonium sulphide acts violently upon it according 
to the following equation : 

C.Hg.O.NO -f 3 (NH,).S = CoH,.OH + TNHj + Ufi 4- 3S. 

No trace of an ethyl-base is formed in this reaction (E. Kopp ; 
Carey Lea). 

The alcoholic solution of ethyl nitrite is known under the 
name of spiHtus aetlieris 7iitrosi and is used as a medicine. 
According to the British Pharmacopoeia it is prepared as 
follows : To 1 pint of rectified spirit of wine add 2 fluid 
ounces of sulphuric acid, stirring them together : then add in 
the same way 2^ fluid ounces of nitric acid. Put the mixture 
into a retort into which 2 ounces of fine copper-wire (No. 25) 
has been introduced and into which a thermometer is fitted. 
Attach a condenser and apply gentle heat ; let the spirit distil 
at a temperature from 170° to 175° (Fah.) until 12 fluid ounces 
have passed over. Then add half an ounce more nitric acid to 
the residue in the retort and distil as before until the whole 
product makes up fifteen ounces. Mix this with two pints of 
rectified spirit, or enough to bring the specific gravity to 0*845. 

In former days this sweet spirit of nitre stood in high repute 
amongst physicians, and is now used as a pleasant and mild 
irritant. 

Ethyl Nitrate, C2H5NO3. 

237 It has already been stated that common nitric acid acts 
as an oxidizing agent on alcohol, and the more violently the 
more nitrous acid it contains. Millon^ showed in the year 
1843 that this oxidizing action does not take place, and that 
nitric ether is fonned, provided that the lower oxides of nitrogen 

» Ann. Chim. Phijs. [3], y\\\. 233. 



»> TEE LTEYL GLOUP. 



pivaeBt ill th*: Lkric -j^yA W •i-estrovtrtl bv the addition of a 
biisSxA quaittity ct urea, iL^: deoi^oipoeidon effected by the iixea 

CO NIL,;, ^ 2 HNO. = 3 H.0 n- CO, + 2 >V 

lo order to prepare ethyl nitrate accc^rding to Millon's prooesB 
a mixture of (?) to 7-5 grams of spirit of specific gravity 0-854, 
and a like quantity of nitric acid of sp^?ific gravity 1-4, is dis- 
tilled with 1 to 2 grains of nitrate of urea at a gentle heat. 
The receiver is charged as s*-.on as ethvl nitrate be<nDS to 
distil over instead of aqueous alcohol, and this point may be 
recogni-jed by the- peculiar odour of the distillate. When seven- 
eighths of this have come over, the operation is stopped, the 
distillate mixed with dilute caustic potash and water, and the 
ether dried over calcium chloride and rectifie<l. 

Carey Lea ^ has improved this method inasmuch as he dis- 
solves from four to five times the quantity of urea recommended 
by Mill^'U in warm alcohol, adding an equal quantity of nitric 
acid of s[Kjr':ific gravity 1*401 and distils the mixture until one- 
fifth of the whole has passed over. To the residue, alcohol and 
nitric a'^id arc again ad«led, and thtrse operations are repeateil 
Foveral times until the whole of the urea is decomposeil. 

Acfording to Heintz- the best pr«.»i>ortion is as follows: 
SO grams of nitric acid of specific gravity 1*4 aro warmed 
with some nitrate of urea, and to this, when it is coM, (10 grams 
of hjnrit of specific gravity O'Sl and lo grams of nitrate of urea 
are ahh.d, and the mixture distilled to one-eighth. A similar 
method has been descnbed by Bertoni^ for the prei>aiation of 
large quantities of the nitrate. 

Ethvl nitrate is also formed, as Porsoz* has shown, when to 
20 grams of j>erfectly pure highly concentrated nitric acid 
eooled ill a mixture of ice and siilt, 10 grani:^ of absolute 
alcohol an? added drop by drop, the mixture being continually 
stirred. In order to sejjarate the other, ice is then added. 

Chajunan and Smith * have not found this method advan- 
tageous and have suggested the following. Two volumes of 
con«'ent.nited sulphuric arid and one volume of fuming nitric 
aci<l, of KjHicific gravity 1*30, which has previously been heated 

* .ViV/iwi. Amri-, Jnuni. (2), xxxii. 178; xxxiiL 8C. 

• Ann, i'li^m. Phinn, i-xxvii. 43. • /At. Drut^tch, Chnn. Ors. ix. 161»2. 

* I'nmpf. linut, Iv. [til, * JoHl-H, Cfwtfl. &>C. XX. 5l*l. 



ETHYL NITRATE. 361 



with a small quantity of urea, are mixed together. To the cold 
mixture a few grams of urea are added, and then gradually one 
part of alcohol for every three parts of the mixture, the whole 
being then well stirred. The nitrate then separates out as a 
light layer. Champion ^ states that ethyl nitrate can be more 
simply obtained by bringing a cold mixture of one part of strong 
nitric acid and two parts of sulphuric acid into a well-cooled 
mixture of sulphuric acid and strong spirit. 

Ethyl nitrate is also formed by the action of ethyl iodide on 
silver nitrate.^ 

Ethyl nitrate prepared according to one or other of these 
various processes, is well washed with water and dried over 
chloride of calcium or ignited carbonate of potash. It is a 
mobile liquid possessing a pleasant smell which how^ever is 
quite diflferent from that of the nitrite. It has a sweet taste, 
but a bitter after-taste. It boils at 86°'3, and has a specific 
gravity at 0** of 11322 (H. Kopp). When ignited it burns with 
a bright white flame. Whilst Millon was ascertaining the 
vapour density of nitric ether according to Dumas's method and 
attempted to seal the neck of the bulb containing the vapour, 
heated above its boiling point, with a blowpipe flame, a violent 
explosion took place which broke the bulb. The vapour, when 
heated to a lower temperature may, however, be inflamed with- 
out explosion. Concentrated caustic potash does not act at 
ordinary temperatures on ethyl nitrate, but an alcoholic solution 
quickly decomposes it with separation of crystals of nitre. 



Phosphites and Phosphates of Ethyl. 

238 Hydrogen Ethyl Phosphite or Uthyl Phosphorous Add, 
HgCCgH^jPOg, is formed when phosphorus trichloride is allowed 
to fall drop by drop into well-cooled spirit of wine of specific 
gravity 0'850.^ 

PCI3 + 2 C.3H,0H -I- H.,0 = H2(C,H5)P03 4- C^H^Cl + 2 HCl. 

The solution is then gently heated in order to drive oflF the 
hydrochloric acid and chloride of ethyl, and the residue is 
allowed to evaporate to a syrupy consistency in a vacuum. The 

^ Vompt. Eciid. Ixxviii. 1150. 

2 Warster, Bcr Dcutsch. Cfcm. Ga^. v. 406. 

« Wurtz, Ann, Vhim. Pkys. [3J, xvi. 218, 



362 THE ETUYL GliOUP. 



acid thus obtained very readily decomposes into alcohol and 
phosphorous acid. The salts, which however do not crystallize 
well, are more permanent than the acid. In order to obtain 
the barium salt, the acid solution is saturated with barium 
carbonate, and filtered from the barium phosphite. The 
other salts can be obtained from the barium salt by double 
decomposition. 

Potassium Ethyl Phosphite forms a thick syrup. 

Barium Ethyl Phosphite, Ba < tj^O^H iPO^* ^^ ^^ amorphous 
deliquescent friable mass. 

Lead Ethyl Phosphite, Pb - urr^H^ipO^* crystallizes in unc- 
tuous, shining scales, unalterable in the air. Its aqueous solution 
gradually deposits lead phosphite. 

Normal Ethyl Phosphite, (C2HJ3PO3. is obtained by acting on 
absolute alcohol with phosphorus trichloride, or better by dis- 
solving sodium in alcohol, evaporating to dryness, and gradually 
adding the calculated quantity of phosphorus trichloride. In 
order to diminish the violence of the reaction, which otherwise 
takes place with evolution of light, the mixture is diluted with 
five volumes of pure ether. The mixture is heated during the 
operation to the boiling point of ether, until no further acid 
vapours are evolved. The ether is then distilled off on a 
water-bath, and the ethyl phos[)hite is obtained by subsequent 
distillation from an oil-bath. It is purified by rectification in a 
current of hydrogen as it undergoes oxidation in the air.^ 

Ethyl phosphite is a colourless disagreeably smelling liquid 
which boils in an atmosphere of hydrogen at 188"* and in the 
air at 191°. It has a specific gravity of 1075 at lo^'o, is easily 
inflammable and burns with a bluish-white flame. It is not 
only soluble in spirit of wine, but also in water. Heated with 
the exactly requisite quantity of baryta it forms alcohol and 
barium diethyl phosphite [P03(C2Hg)2].,Ba, which remains as a 
deliquescent crystalline mass. Other diethyl phosphites may 
be obtained from this by double decomposition ; these are all 
soluble and difficultly or non-crystallizable. When diethyl 
phosphite is heated with an excess of baryta solution the soluble 
barium salt of dibasic ethyl phosphoric acid, PC)3(C2H^)Ba, 
crystallizes out. The other salts of this acid do not crystallize. 
The existence t^f two ethyl phosphoric acids, the one monolxi.sic 

* Hailtoii, C/u/n, Soe. Joum, vii. 210. 



PHOSPHITES OF ETHYL. 363 



(Wurtz) and the other dibasic (Railton), can be explained by the 
following formulae ; 

Wurtz's Acid. Ilailton*s Acid. 

/H /C2H5 

O = P-OH O = P-OH 

NOCgHj, \0H 

According to this, the latter acid should be identical with 
ethyl phosphinic acid obtained by oxidizing ethyl phosphine, but 
this is not the case. Whilst the latter is a very stable compound, 
the dibasic ethyl phosphoric acid cannot be isolated, and if the 
barium salt be boiled with water, barium phosphite and alcohol 
are formed.- These compounds require re-investigation. 

Chloride of Ethyl Phosplwrous Add, P(0C2Hg)Clg, is formed 
when absolute alcohol is allowed to run into the calculated 
quantity of phosphorus trichloride.^ It is a strongly refracting 
fuming liquid, boiling at 117® and having a specific gravity 
at 0° of 1*31G. Water acts violently upon it with formation 
of phosphorous acid, hydrochloric acid and alcohol. By the 
further action of alcohol it is transformed into the compound 
P(0C,H^,C1. 

The three compounds obtained by the action of phosphorus 
trichloride on alcohol, yield with chlorine or bromine, the ethyl 
group in the form of haloid salt : 

P(OC2H,)3 4- CI2 = PO(OC2H,)2Cl -f CgH.Cl. 

In this case the chloride of diethylphosphoric acid is ob- 
tained, whilst the chloride of diethylphosphorous acid yields 
dichloride of ethyl phosphoric acid, PO(C2H50)Cl2, and the 
chloride of ethyl phosphorous acid is converted into phosphorus 
oxychloride.*^ 

Acid Ethyl Pyrophoffjyhite, O < p/rjp^xj'*N(-\fi» is not known in 

the free state, but its zinc salt is produced together with other 
products when zinc ethyl is heated to 140° with phosphorus 
pentoxide. The barium salt has the composition P205(C2H5)2Ba.^ 
239 Fhosphaies of Ethyl, Tribasic orthopho.^^phoric acid forms 
three ethyl compounds, two acid and one normal. 

( OH C OH ( OC2H. 

po ' OH po \ ocH. po I oan 



I 



' Mentschutkin, Ann, Chcni. PJiarm. exxxix. 313, 
- W^ichelhaus, Ann. Chnn. Phann. Sum)!, vi. 257. 
^ Dilling, ^cifsch. Chan, [2], ui. 266. 



36 1 THE ETHYL GROUP. 



Ethyl Fhogphoric Acid, VOfifi^{OW)^ was discovered in 
1820 by Lassaigne^ and afterwards investigated by Pelouze* 
and Liebig.^ In order to prepare it, equal parts of vitreous 
phosphoric acid and strong spirit are heated for some minutes to 
from GO** to 80^ After standing for twenty-four hours the liquid 
is diluted with eight vohimes of water, neutralized with barium 
carbonate, and boiled in order to drive oflF the excess of alcohoL 
When the liquid has cooled down to 70", it is filtered and allowed 
to stand in order that the barium salt may crystallize out The 
aqueous solution is then decomposed with the requisite quantity 
of sulphuric acid. The lead salt may also be prepared, and 
this decomposed by sulphuretted hydrogen. The filtrate is 
first evaporated over a lamp, and is then concentrated by stand- 
ing over sulphuric acid. An oily odourless liquid is thus 
obtained which possesses a biting acid taste. When heated, 
it evolves the vapours of alcohol and ether, and afterwards 
ethylene gas. Its aqueous solution may be concentrated by 
boiling up to a certain point without decomposition ensuing. 

Ethyl phosphoric acid is also formed when ether is treated 
with concentrated phosphoric acid.* It may also be prepared 
by acting with phosphorus oxychloride on aqueous spirit (Schiff), 
as well as by the action of iodine and phosphorus in the 
preparation of ethyl chloride (Reynoso). 

The ethyl phosphates of the alkaline metals are deliquescent, 
and crystallize imperfectly. 

Barium Ethyl Phosphate, BaCgH^PO^, crystallizes in short 
quadratic prisms or six-sided tables, and possesses an unpleasant 
bitter saline taste. It loses its water of crystallization at 120^ 
Its solution saturated at 40° deposits crystals both on cooling 
and on heating. 

Lead Ethyl Phosphate, PbC2H5P04 + HgO, is the least soluWe 
of all the ethyl phosphates, and is therefore easily obtained by 
precipitating the foregoing salts with sugar of lead. It can be 
obtained in the crystalline state from solution in boiling 
water. 

Anenic Ethyl Phosphate, As2(C2HgP04)3, is formed by dis- 
solving arsenic trioxide in a boiling solution of the acid, and 
forn)8 fine feathery needles. 

Chloride of Ethyl Phosphoric Acid, P02(C2H5)Cl2, is not only 
formed by the methods above described, but also when equal 

> Ann. Chhn. PhyH. [2], xiii. 294. • Ih. Hi. 87. 

' Ann. Phnnrt. vi. \A\), * Vugeli, Ann. Chrm, Pharw, Ixix. 180. 



PHOSPHATES OF ETHYL. 365 



molecules of alcohol and phosphorus trichloride are allowed to 
act upon one another. It is an oily, readily decomposable sub- 
stance, which, when distilled in a current of hydrogen, boils 
pretty constantly at 167^ 

Diethyl Phosphoric Acid, 11(02^^5)2^04. In order to pre- 
pare this acid, phosphorus pentoxide is allowed to deliquesce 
under a bell-jar in the vapours of anhydrous alcohol or ether. 
After one or two weeks a syrupy liquid is formed which con- 
tains the above compound, together with phosphoric acid, ethyl 
phosphoric acid, and frequently traces of triethyl phospliine. 
The easily soluble lead diethyl phosphate Ls then prepared, and 
this decomposed by sulphuretted hydrogen, the filtrate being 
allowed to evaporate in a vacuum over sulphuric acid, when the 
acid is obtained as a non-crystallizable syrup. The diethyl- 
2)hasphates are soluble in water and easily crystallizable. 

Lend Diethyl Phosphate, Pb(C2H5)4(P04)2. If the impure 
acid obtained as above described be saturated with white-lead, 
and the filtrate evaporated, tablets of a difficultly soluble lead 
salt first separate out, and the solution becomes acid. If this 
be again neutralized with white-lead, an insoluble lead pre- 
cipitate is thrown down, and the filtrate yields on evaporation 
crystals of lead diethylphosphate, which may be purified by 
recrystallization. The salt is deposited in needles easily soluble 
m water and in hot spirit. They melt at 180% and the fused 
salt cools to a stellar crystalline mass. 

Chloride of Dicthylphosphoric Acid, P03(C2H5)2C1, has been 
already mentioned (see p. 363). It is formed by the action of 
phosphonis oxychloride on the calculated quantity of alcohol, 
and is a liquid decomposing on distillation. 

Normal Ethyl Phosphate, {O^^^O^, was first obtained by 
Vogeli by heating lead diethyl phosphate to 190° : 

Pb(C,H,),(PO,), =. (C2H,),(P0,) + PbC,H,PO,. 

It is also formed when silver phosphate is heated to 100**^ 
with ethyl iodide, as well as when phosphorus oxychloride,- or 
pentachloride * acts on sodium ethylate or absolute alcohol : * 

POCI3 + 3 HO.C2H5 = PO(OC2H5)3 + 3 HCl. 
It has already been stated that small quantities of these 

1 Clermont, Ann, Chim. Phys. [3]» xUv. 330. 

* Linipricht, Ann. Chcm. Pharm, cxxxiv. 347. 

* Geuther and Bischoff, Joum, PrakL Chtm [2], vii. 101. 

* Schiff, Ann. Chrm. Pharm. ci. 299. 



366 THE ETHYL GROUP, 



compounds are also formed when alcohol vapour acts upon 
phosphorus pentoxide. If the reaction be allowed to take 
place quickly, a considerable quantity is formed. According to 
Carius^ the pentoxide should be mixed with three or four times 
its volume of anhydrous ether, and then half the theoretical 
cjuantity of alcohol added, and the ethyl phosphate separated 
from the diethylphosphoric acid by distillation. 

Ethyl phosphate is a colourless liquid possess! n<^ a peculiar 
pleasant smell and a burning taste, having at 12° a specific 
gravity of 1072 and boiling at 215°, though towards the end of 
the distillation the boiling-point reaches as high as 240^ and a 
black acid residue remains. In a current of hydrogen, on the 
other hand, it boils constantly at 203** (Wichelhaus). It is 
miscible with water, and the solution soon becomes acid with 
formation of diethylphosphoric acid (Carius) ; this decomposition 
\akes place, however, very slowly (Limpricht). 

Ethyl Pyropliospliate, {G^^^jd^, is obtained by heating 
silver pyrophosphate with ethyl iodide to 100°, as an oily liquid 
possessing a peculiar smell and a burning taste. It is soluble 
in water, alcohol, and ether, and its aqueous solution soon 
becomes acid.* 



i 



The Arsenites, Arsenates, and Borates of Ethyl. 

240 Ethyl Ar senile, {C^^^PisO^, is formed by the action of 
ethyl iodide on silver arsenite, as well as by heating together 
ethyl silicate and arsenic trioxide to 200°, when silica or an ethyl 
polysilicate separates out. It is, however, best obtained by 
treating arsenic tribromide with sodium e thy late, an excess of 
the latter substance being carefully avoided, as it acts at once 
upon the ethereal salt with formation of common ether. In 
order to decompose the excess of arsenic tribromide, the re- 
sulting material is treated with dry ammonia, which unites with 
the bromide to form a compound insoluble in spirit and in ether. 
It is then filtered off, and the arsenite purified by distillation. 
It is a colourless liquid boiling at IGa** to 1 GG*', and having a 
specific gravity of 1224 at 0^ It is quickly decomposed by 
water, with separation of arsenic trioxide.' 

^ Carins, Ann. Chem. Pharm, czxxWi. 121. 

• Clemiont, Ann, Chem Pharm. xci. 376. 

* Clennont, Bull. Soc, C'Aim. [21 viii. 20^; xiv. ^9 



ARSENITES, ARSENATES, BORATES OF ETHYL. 367 



Ethijl Arsenate, (CgHJgAsO^, is obtaiaeJ by beating silver 
arsenate to 100'* with the calculated quantity of iodide of ethyl 
diluted with ether. It is a colourless liquid, which boils under 
the ordinary atmospheric pressure, with slight decomposition at 
235° to 238**, but may be distilled in a vacuum without de- 
composition. It dissolves in water with decomposition, the 
solution yielding all the reactions of arsenic acid.^ 

Ethyl Orthoborate, (0.2115)3603, was discovered by Ebelmen in 
1845, and investigated by this chemist and Bouquet. They 
obtained it by saturating alcohol with gaseous boron trifluoride.^ 
These experiments were afterwards corroborated by Bowman,' 
and H. Rose noticed that ethyl borate could also be easily pre- 
pared by distilling a mixture of two parts of anhydrous borax 
and three parts of potassium ethyl sulphate.* Frankland em- 
ployed this reaction in his investigation on the organic com- 
pounds containing boron,^ and found that from the distillate, 
which contains a large quantity of alcohol, ethyl borate could 
be best separated by the addition of one-fourth part its weight 
of fused calcium chloride ; after this has dissolved, two layers of 
liquid make their appearance, of which the upper one contains 
the whole of the ethereal salt, and this can be purified by 
fractional distillation. It also is formed by heating boron trioxide 
with alcohol for some time to 120°, and may be readily obtained 
from the portion of the distillate coming over above 100°, by 
addition of a small quantity of sulphuric acid. 

Ethyl borate is a thin colourless liquid boiling at 120°, having 
a specific gravity of 8G1 at 26°'5, a vapour density of 5*14, 
j\nd burning with a green flame. It has a peculiar pleasant 
smell and a hot bitter taste. It is easily decomposed by water, 
with separation of boric acid. When heated with boric trioxide, 
ethyl metabarate, (CaHJ^BaO^ is formed as a thick colourless 
liquid, converted at 200° into orthoborate and ethyl tribarate, 
C2H5B3O5. This latter is a gummy mass, which, like the other 
borates is decomposed by water, with separation of boric acid.*^ 

» Clermont, Bull. Soc. Chim. [2], viii. 206 ; xiv. 99. 

* Ann. Chim, Phys. [3], xvii, 65. 
3 Fhil, Mag. [3], xxix. 546. 

* Fogg. Ann. xcviii, 245. 

» Ann. Ghem. Pharm. cxxiv. 129 ; Phil. Trans. 18C2, 1C7. 

* Scliiff, Ann. Chcm. Pharm, Sappl. v, 154. 



36ft THE ETHYL GROUP. 



compounds arc also formeil when alcohol vapoar acts apon 
phosphorus pentoxide. If the reaction be alloweil to take 
place quickly, a considerable quantity is formed. Acconling to 
Carius^ the pentoxide should be mixed with three or four times 
its volume of anhydrous ether, and then half the theoretical 
r|uantity of alcohol added, and the ethyl phosphate separated 
from the diethylphosphoric acid by distillation. 

Ethyl phosphate is a colourless liquid possessing; a peculiar 
pleasant smell and a burning taste, having at 12"* a specific 
gravity of 1072 and boiling at 215**, though towards the end of 
the distillation the boiling-point reaches as high as 240", and a 
black acid residue remains. In a current of hydrogen, on the 
other hand, it boils constantly at 203"* (Wichelhaus). It is 
miscible with water, and the solution soon becomes acid with 
formation of diethylphosphoric acid (Carius) ; this decomposition 
\akes place, however, very slowly (Limpricht). 

Ethyl Pyrophosphate, (CjHj)^?^©^, is obtained by heating 
silver pyrophosphate with ethyl iodide to 100°, as an oily liquid 
possessing a peculiar smell and a burning taste. It is soluble 
in water, alcohol, and ether, and its aqueous solution soon 
becomes acid.- 



The Arsenites, Arsexatks, and Borates of Ethyl. 

240 Ethyl Arsenitc, (C2H5)3As03, is formed by the action of 
ethyl iodide on silver arsenite, as well as by heating together 
ethyl silicate and arsenic trioxide to 200°, when silica or an ethyl 
polysilicate separates out. It is, however, best obtained by 
treating arsenic tribromide with sodium ethylat^, an excess of 
the latter substance being carefully avoided, as it acts at once 
ujKm the ethereal salt with formation of common ether. In 
order to decompose the excess of arsenic tribromide, the re- 
sulting material is treated with dry ammonia, which unites with 
the bromide to form a compound insoluble in spiiit and in ether. 
It is then filtered off, and the arsenite purified by distillation. 
It is a colourless liquid boiling at 165° to 1 GG°, and having a 
specific gravity of 1*224 at 0°. It is quickly decomposed by 
water, with separation o'f arsenic trioxide.^ 

' TarinR, Ann, Chem. Pharm, czxzvij. 121. 

• <'liTmont, Ann. Chnn Pharm, xci. S76. 

* i'lennont, HulL Soc, Chiin. [2], viii. 20^; xiv. ^9 



ARSENITES, ARSENATES, BORATES OF ETHYL. 367 



Ethyl Arsenate, (C2H5)3AsO^, is obtaiued by beating silver 
arsenate to 100'' with the calculated quantity of iodide of ethyl 
diluted with ether. It is a colourless liquid, which boils under 
the ordinary atmospheric pressure, with slight decomposition at 
235° to 238°, but may be distilled in a vacuum without de- 
composition. It dissolves in water with decomposition, the 
solution yielding all the reactions of arsenic acid.^ 

£thyl Orthohorate, (02115)3608, was discovered by Ebelmen in 
1845, and investigated by this chemist and Bouquet. They 
obtained it by saturating alcohol with gaseous boron trifluoride.* 
These experiments were afterwards corroborated by Bowman,' 
and H. Rose noticed that ethyl borate could also be easily pre- 
pared by distilling a mixture of two parts of anhydrous borax 
and three parts of potassium ethyl sulphate.* Frankland em- 
ployed this reaction in his investigation on the organic com- 
pounds containing boron,^ and found that from the distillate, 
which contains a large (Quantity of alcohol, ethyl borate could 
be best separated by the addition of one-fourth part its weight 
of fused calcium chloride ; after this has dissolved, two layers of 
liquid make their appearance, of which the upper one contains 
the whole of the ethereal salt, and this can be purified by 
fractional distillation. It also is formed by heating boron trioxide 
with alcohol for some time to 120°, and may be readily obtained 
from the portion of the distillate coming over above 100°, by 
addition of a small quantity of sulphuric acid. 

Ethyl borate is a thin colourless liquid boiling at 120®, having 
a specific gravity of 8G1 at 26°*5, a vapour density of 5*14, 
i^nd burning with a green flame. It has a peculiar pleasant 
smell and a hot bitter taste. It is easily decomposed by water, 
with separation of boric acid. When heated with boric trioxide, 
ethyl mctaborate, (CoHJ^BgO^, is formed as a thick colourless 
liquid, converted at 200° into orthoborate and ethyl triborate, 
C2H5B3O5. This latter is a gummy mass, which, like the other 
borates is decomposed by water, with separation of boric acid.* 

» Clermont, Bull. Soe. Chim, [2], viii. 206 ; xiv. 99. 
^ Ann. Chim. Phys. [3], xvii, 65. 
8 phii^ jijag. [3], xxix. 546. 

* Fogg. Ann. xcviii. 245. 

» Ann. Chem. Pharm, cxxiv. 129 ; Phil. Trans. 18C2, 167. 

• Scliiff, Ann, Chem, Pharm, Snppl. v. 154. 



368 THE ETHYL GROUP. 



Ethyl Silicates. 

241 Ethyl Orthosilicatc, (CgHJ^SiO^, is formed, as Ebelmen* 
has shown, by the action of silicon chloride on absolute alcohoL 
It is a mobile pleasantly smelling liquid, having a strong taste of 
peppermint, boiling at 165°-5, and having at 0° a specific gravity 
of 967(). This ethereal salt is easily inflammable, burning 
with a brilliant white flame, depositing clouds of very finely 
divided silica, which is insoluble in alkali. It is slightly 
attacked by water, in which it is insoluble. On exposure to 
moist air, it gradually decomposes, and a small quantity which 
Friedel and Crafts^ had kept for three years in a badly stoppered 
bottle was completely converted into a mass of silicic acid, 
which was so hard that it scratched glass. Absolute alcohol 
dissolves this ethereal salt without alteration, and aqueous 
spirit decomposes it quickly, with formation of ethyl polysiU- 
cates. When ethyl silicate is heated with silicon chloride in 
a closed tube to 150^ one or other of the following chlorhydrins 
are formed, according to the quantities of the constituents 
present : 

Boiling-point. 

Si(OCjH5)3Cl .... 155°-7 to 157° 
SiXOCjHJ^CIj. . . . 136° to 138° 
Si(0CjH5)Cl, .... 103° to 105° 

These compounds are colourless liquids, easily decomposed by 
water, and converted by the action of ethyl alcohol into ethyl 
silicate, whilst the other alcohols give mixed ethers, as, for 
example, the following: 



Boiling-point. 

SiCOC.HJgOCHs. . . . 155° to 157 
Si(0CJHj)j(0CH3), . . 143° to 147 
Si(OCjH5)(OCHj32. . . 133° to 135 



■»NwO 



"O 



Ethyl Disilicate, (CgHJ^SijOy, is formed by the action of 
silicon chloride on alcohol containing a small quantity of water, 
and is hence usually formed in the preparation of the ortho- 
silicate : 

2 SiCl, + 6 HO.CgH, + H.0 = O I ||[oc'h'J' + ^ "^'• 

^ Ann. C^im. Phyt, [3], xvi. 144. * Bulh S(*e. Chim. v. 174, 288. 



ETHYL OXALATE. 369 



It is an oily liquid, resembling the orthosilicate in its smell ; 
is easily inflammable, boils between 233** and 234'', and possesses 
at 0** a specific gravity of 10196 (Friedel and Crafla). 

Ethyl MetdsiliccUe, (€2115)28108. This is formed, according to 
Ebelmen, by the action of silicon chloride on aqueous alcohol. 
It is a slightly smelling liquid, which boils at 350'', and is de* 
composed by water. Heated with a small quantity of water, a 
gummy mass is obtained, which on cooling forms a glassy solid, 
and is said to have the composition (02115)281^0^. Friedel and 
Crafts were unable to obtain this compound 



Ethyl Carbonates. 

242 Hydrogen Ethyl Carbonate or Ethyloarbonic Add, 
H(C2H5)C03. This compound is not known in the free state, but 
its corresponding potassium salt has been obtained by Dumas 
and Feligot* by passing dry carbon dioxide into a solution of 
caustic potash in absolute alcohol, the solution being well cooled : 

CO2 + C,H,.OH + KOH = CO { Q J^j + H2O. 

At the same time both normal and acid potassium carbonate 
are formed. In order to separate these^ the liquid, as soon as a 
considerable quantity of precipitate has been formed, is shaken 
with an equal volume of ether and the solid mass collected on a 
filter. From this mass absolute alcohol dissolves only the ethyl 
potassium carbonate, and this may be obtained, on addition of 
ether, in the form of a pearly crystalline precipitate, which is 
decomposed slowly by aqueous alcohol, but quickly by water : 

CO j ^^^j + H2O = CO-f ^5 + HO.C2H5. 

The corresponding sodium compound is formed, according to 
Beilstein, as a white precipitate, when carbon dioxide acts, on an 
alcoholic solution of sodium ethylate,^ and when normal ethyl 
carbonate is heated with sodium ethylate to 120** (Geuther) : 

Norninl Ethyl Carbonate, (G^^\CO^. This body was dis- 
covered by Ettling' in 1836, and obtained by him, 



Ann, Chim. Phya, Ixxiv. 9. ' Ann, Chefn, Pharm, 

' Ann. Phartn, xix. 17. 



VOL. in. B 






370 THE KTHYL GROUP. 



with carbon monoxide and other products, by heating pure ethyl 
oxakte, (€2115)20204, with sodium. Cahours^ then showed that 
it was also formed when the metal potassium was employed. 

This peculiar reaction has not as yet found any satisfactoiy 
explanation. Ethyl oxalate is indeed distinguished from ethyl 
carbonate by an increment of CO, but as in the formation of 
this latter compound the alkali metal disappears, the decompo- 
sition cannot, as Gmelin^ remarks, be explained by the supposi- 
tion of a catalytic action. Hence it is probable that the following 
reaction takes place : 

2 (Cfi^^Cp^ + Nag = (CjH^aCOa + 2 CoH^ONa + 3 CO. 

The other products which have been observed are formed by 
the action of sodium ethylate on ethyl oxalate. Geuther,' who 
has investigated this subject carefully, states that oxalic ether 
can also be converted into ethyl carbonate when it is treated 
with sodium ethylate, and Dittmar and Cranston* came to the 
same conclusion, finding that, when one molecule of sodium 
ethylate was used with four molecules of ethyl oxalate, three 
molecules of ethyl carbonate, and three molecules of carbon 
dioxide, together with about 0*4 molecule of alcohol, as well 
as other products not exactly examined, w^ere formed. Accord- 
ing to Geuther, ethyl formate is also produced, as well as a 
small quantity of a crystalline acid and two different brown 
amorphous bodies having an acid character. 

Ethyl carbonate is prepared by distilling a mixture of ethyl 
potassium carbonate and ethyl potassium sulphate,* as well as 
by acting on ethyl iodide with silver carbonate.^ It is a colour- 
less, pleasantly smelling liquid, boiling at 120**, and having a 
specific gravity of 9998 at 0° (Kopp) and a vapour density of 
4*09 (Cahours). It is easily inflammable, burning with a blue 
flame. Treated with chlorine, it yields substitution-products, of 
which the last is perchlorethyl carbonate, (02015)2005.' This 
crystallizes in small white needles; which haTe a faint smell, melt 
at 85** — 8G^ and may bo partially distilled without decomposition, 
though yielding at the same time carbon dioxide, hexchlore thane, 
and trichloracetyl chloride.^ 

* Jnn. Phafm. xlvii. 291. • BandboitJc, ix. 182. 

> Zeitsch, Chem, 1868, 662. * Joum, Chrm, Soe. (2J, vil 441. 

» Chancel, Compt, Rend, xxxii. 687. • Clennout, ib, xxxix. 338. 

" Cahoura, Ann. Chem, Pharm. xlvii. 291. 

' Malaguti, Ann. Chim, Phys, [3], xvi. 80. 



ETHYL OBTHOCARBONATE. 371 



CO { qS'cJ' = CjCl, + CO, + CClj^CGCl. 

X 2 5 

Ethyl OrtJuHXLrbonate, CiOG^H^)^ was discovered by Basset,^ 
who prepared it by the action of sodium on a solution of chloro- 
picrin in absolute alcohol : 

4NaOC2H^ + CCI3.NO, = CCOCjHg), + 3NaCl + NaNO^ 

It is an aromatic-smelling liquid, boiling at 158** — 159^ and 
easily decomposed by alcoholic potash, with formation of potas- 
sium carbonate. When heated for six hours with boron trioxide 
to 100®, the following reaction takes place : ^ 

(C^H^.CO, + 2 B,03 = (C^H^gCOs + {G.U^^Bfir 

( CI 
Hthyl Chlorocarbonate, CO -J Qp tt . This compound was 

first obtained in 1833, by Dumas,* by the action of carbonyl 
chloride on absolute alcohol : 

C0{ g[ + HOC,H, = CO { gJ.^H^ = HCl. 

It is a colourless mobile liquid, boiling at 94^ and having a 
specific gravity of 1*133 at 15^ It possesses a suffocating and 
irritating odour, but if the vapour be mixed with a large quan- 
tity of air, it possesses a pleasant smell. In contact with warm 
water, partial decomposition occurs, with formation of hydro- 
chloric acid, and with alcohol it decomposes slowly, with forma- 
tion of ethyl carbonat^.^ This last ether is also formed when 
ethyl chlorocarbonate is treated with sodium : 

2C0 { gi^^H, + ^S = CO { gg;H» + CO + 2 NaCl. 

A similar reaction also occurs when this chloro-ether is acted 
upon with sodium ethyl carbonate : * 

CO { OC,H, + CO { ggf * = CO { gg;«; + CO, + NaCl. 
243 Ethyl Carbamate, QO < Qptx was obtained by Dumas,^ in 



* Joum, Chem, Soc, [2], ii. 198 ; Ann, Chem. Phamu czxzii. 54. 

* Ann. Chim. Phys, [2], liv. 226 ; Ann, Phamu x. 277. 
' Batlerow, Zeitsch, Chem, 1863, 484. 

* Wilm and Wischin, Ann. Chem, Pharm, cxivii. 160. 

* Wyss, Ber. Deutsch. Chem. ties. ix. 847, 

* Ann, Chim, Phys. liv. 225. 

BBS 



rs 



372 THE ETHYL GROUP. 



1833, by acting with ethyl chlorocarbonate on ammonia, and he 
termed it urethane, because it may be considered as a compouad 
of urea with ethyl carbonate. This name was afterwards changed 
in accordance with the usually adopted nomenclature for the 
carbamine salts. Ethyl carbamate is also formed when the 
carbonate is allowed to remain in contact with cold ammonia, 
whilst when heated, urea is formed.^ It is also produced by the 
action of cyanogen chloride on alcohol.* 

CICN 4- 2 C^H.OH = C0H5CI + (. 2 O* } ^^• 

Ether may be also employed instead of alcohol, the reaction 
then taking place slowly.^ It is also formed together with ethyl 
allophanat^, when the vapour of cyanic acid is passed into 
alcohol or ether : * 

HO.CN + C.,H,.OH = ^ ^^ \- CO. 



_ NHa 
- C AO 1 



In order to prepare this compound, ethyl carbonate is allowed 
to remain in contact with an equal volume of aqueous ammonia 
until the ether has all dissolved, and then the liquid is allowed 
to evaporate in a vacuum. In this way fine transparent crystals 
are obtained, easily soluble in water and alcohol. Ethyl carba- 
mate melts below 100^ and on cooling, again soli<lifies to a 
spermaceti-like mass. When perfectly dry, it boils without 
decomposition at 180°, subliming, however, at a lower tempera- 
ture. In the moist state it partially decomposes on heating, 
with formation of ammonium carbonate. 

Ethylamidomcihyl Carbonate , CO i ^i/ it , is formed by 

acting on ethyl chlorocarbonate with a strong aqueous solu- 
tion of methylamine. It is a colourless not unpleasantly 
smelUng ethereal liquid, lighter than water, and boiling at l70^ 
The ether produced in a corresponding way from ethylamine is a 
ver^ similar body, boiling between 175-G°.* 

' Cahoum, Compt, Rend. xxi. 121>. 

« Wtirta, Compt. Rrnd. xxii. 503. 

» Oqoz, JnsL 1857, 207 

^ Licbi^ nnd Wohler, Ann. Vhem. Pharm. liv. 870 ; Iviii. 260. 

' Schn>inrr, Joum. PmU. Chem. (2|, xxi 1:J1, 



ETHYL ALLOPHANATE. 373 



Ethyl Allophanate, C2N2H3O8.C2H5. 

244 This ether was first obtained by Liebig and Wohler, in 
1830, by passing the vapour of cyanic acid into alcohol, and 
described by them under the name of cyanic ether.^ Fifteen 
years later they found that this compound contains neither 
cyanic acid nor cyanuric acid, but a new acid, for which they pro- 
posed the name of allophanic acid, because it is a substance 
different from that which from its mode of formation might 
have been expected.^ Absolute alcohol absorbs the vapour of 
cyanic acid with such avidity that the liquid begins to boil. 
Hence it is best to dilute the alcohol with an equal volume of 
ether, and to allow the saturated liquid to stand for twenty- 
four hours, when the compound crystallizes out in fine prisms, 
having a pearly lustre. These are best obtained by saturating 
ether with cyanic acid, evaporating, and then adding 95 per 
cent, spirit, and allowing the solution to stand. 

Ethyl allophanate is also formed when a solution of potassium 
cyanate in aqueous alcohol is acidified,^ as likewise, together 
with ethyl carbonate, when ethyl chlorocarbonate is brought 
into contact with potassium cyanate and absolute alcohol : * 

2 CICO2C2H5 + 2 KOCN 4- 3 HOC2H, = 2 KCl 
+ 2 (C,Ufi)fiO + C2H3N3O3C2H,. 

Ethyl allophanate is tasteless and odourless, only slightly 
soluble in cold water, alcohol, and ether, but more soluble in the 
warm liquids. It also dissolves without alteration in hot nitric 
acid and dilute sulphuric acid. It melts at 190-1*, and decom- 
poses when it is allowed to stand at this temperature for some 
time, with formation of alcohol and cyanuric acid (Amato). Its 
constitution is recognised by the fact that it is also formed when 
ethyl chlorocarbonate acts upon urea : ^ 

/NH^ /NH2 

CO + CICO.OC2H, = CO + HCl. 

NNH^ \NH-CO.OC2H5 

It is also formed by the direct union of cyanic acid and ethyl 

• Fogg, Ann. xx. 396. ' Aiui. Chem. Pharm. lix. 291 

• Amato, Oatz. Chim. Ital. iii. 469. * Wilm, Lkbig's Ann, czcii. 24 

• Wilm and Wischin, Ann, Chan. Pfutrtn, cxlvii 150. 




374 THE ETHYL GROUP. 



carbamate, which is the first product of the action of cyanic 
acid on alcohol (par. 243).^ 

/NH- /NH-CO-NH, 

CO + NCOH = CO 

\OC2H5 XOCjH^. 

On the other hand, the allophanate is decompoeed into two 
molecules of ethyl carbamate by heating it with spirits of wine 
to 160°. If ethyl allophanate be heated with ammonia to 100* 
biuret is formed : 

/CO.NIL /CO.NHL 

NH + NIL = NH + HO.C.H,. 

\CO.OC0H5 \CO.NH, 

Hence biuret (Vol. I. p. 652) is the amide of allophanic acid, 
a substance which does not exist in the free state, although a 
series of ethers and a few unstable salts are known. These 
latter are obtained by the action of alkalis and alkaline earths 
upon the ethers, and their aqueous solutions decompose very 
easily on heating with formation of urea. 

Diethyl CijanamidocarboncUe, N(CN)(CO.OC^5)2, is formed 
by the action of ethyl chlorocarbonate on sodium cyanamide 
(Vol. I. p. 676). It is easily soluble in alcohol, separating 
from the solution in large glistening crystals. When heated 
with sodium ethylate the sodium salt, N(CN)(C0.0C2HJNa, is 
formed, crystallizing in glistening crystals which melt at 241®. 
Concentrated sulphuric acid acting upon this latter compound, 
yields the monethyl ether, N(CN)(CO.OC2H5)H, a yellowish 
syrupy liquid having an acid reaction and a burning taste. This 
is decomposed by boiling water into carbon dioxide and alcohol 
If the sodium salt be heated with ethyl iodide, an ether is 
formed, having the composition N(CN)(CO.OC2H5)C2H5; this 
is an oily liquid boiling at about 213°.* 

Diethyl Guanidine Carbonate, CNHCNH.CO.O.CjHj),, is 
formed by the action of ethyl chlorocarbonate on guanidine 
(Vol. I. p. 680) : 

NH- NH.CO.OC.H. 

I I 

C=NH + 2CICO.OC0H, = C-NH + iHCl. 



i 



Hj NH.CO.OC2H5. 

* Hofmnnn, Ber, l>ufitrh, Chem. Gen. iv. 262. 
3 Ranler, Journ. Pnkt. Chrm, [2], xvi. 120. 



ETHYL FORMATE. 375 



This compound is insoluble in water, but dissolves readily in 
alcohol, crystallizing in colourless crystals melting at 162°. 
When heated with alcoholic ammonia to 100^ the monethyl 
compound of urethane is produced : 

NH.CO.OaH, NR 



'2"5 -J' "2 

C=NH + NH3 = C=NH + NH2.CO.OC2H5 

NH.CO.OaH. NH.i 



..^.CO.OC,H,. 



This monethyl ether is a powerful base, crystallizing from 
aqueous solution in rhombic tablets and forming a series of 
"well-crystallizable salts.^ 



Ethyl Formate, C2H5CHO2. 

345 In the communication already referred to under formic 
acid, Arfvedson, in 1777, states that when formic acid is distilled 
with spirit of wine, oily drops of a liquid appear, the properties 
of which he did not further investigate. Five years later 
Bucholz obtained this ether in the same way, separating it from 
the alcoholic distillate by means of water. 

According to Kopp^ ethyl formate is best prepared by 
bringing 8 parts of anhydrous sodium formate into a retort and 
pouring on it a mixture of 7 parts of 88 per cent, spirit and 
11 parts of sulphuric acid, so much heat being evolved that the 
ether distils and may be collected in a well-cooled receiver. 
This ether is also formed as a by-product in the preparation of 
ethyl oxalate (Lowig), and also by heating hydrogen ethyl 
oxalate, (C2H5)HC204, with glycerin to 100^ the reaction which 
here takes place being exactly analogous to that of the formation 
of formic acid from oxalic acid. It is not necessary for this 
purpose to prepare pure ethyl oxalic acid, but the crude product 
obtained by heating oxalic acid for a long time with alcohol 
may be employed.^ A still more simple method is to heat 
anhydrous glycerin with equal molecules of alcohol and oxalic 
acid, connecting the flask with a reversed condenser until com- 
plete decomposition has occurred ; the oxalic acid then requires 
to be warmed and the ether distils over.* 

' NeiK'ki, Bf-r. Dfutsrh, Chrm. Ges. vii. 1588 ; Jourti. Pralt. Cluia, [2], xvii. 
237. 

' Ann. Chein, PhannAv.no. - Church, /*/(?/. i/r/y. [4 J, xi. 527. 

* Lorin, Bull, Soc, Chim \2\, v. 12 



366 THE ETHYL GROUP. 



compounds are also formed when alcohol vapour acts upon 
phosphorus pentoxide. If the reaction be allowed to take 
place quickly, a considerable quantity is formed. According to 
Carius^ the pentoxide should be mixed with three or four times 
its volume of anhydrous ether, and then half the theoretical 
quantity of alcohol added, and the ethyl phosphate separated 
from the diethylphosphoric acid by distillation. 

Ethyl phosphate is a colourless liquid possessin<( a peculiar 
pleasant smell and a burning taste, having at 12** a specific 
gravity of 1072 and boiling at 215°, though towards the end of 
the distillation the boiling-point reaches as high as 240°, and a 
black acid residue remains. In a current of hydrogen, on the 
other hand, it boils constantly at 203° (Wichelhaus). It is 
miscible with water, and the solution soon becomes acid with 
formation of diethylphosphoric acid (Carius) ; this decomposition 
\akes place, however, very slowly (Limpricht). 

Etkyl Pyrophosphate, {G^^^fi^, is obtained by heating 
silver pyrophosphate with ethyl iodide to 100°, as an oily liquid 
possessing a peculiar smell and a burning taste. It is soluble 
in water, alcohol, and ether, and its aqueous solution soon 
becomes acid.* 



The AnsENiTRs, Arsenates, and Borates of Ethyl. 

240 Ethyl Arsenite, (C2H5)3As03, is formed by the action of 
ethyl iodide on silver arsenite, as well as by heating together 
ethyl silicate and arsenic trioxide to 200°, when silica or an ethyl 
polysilicate separates out. It is, however, best obtained by 
treating arsenic tribromide with sodium ethylate, an excess of 
the latter substance being carefully avoided, as it acts at once 
upon the ethereal salt with formation of common ether. In 
order to decompose the excess of arsenic tribromide, the re- 
sulting material is treated with dry ammonia, which unites with 
the bromide to form a compound insoluble in spiiit and in ether. 
It is then filtered off, and the arsenite purified by distillation. 
It is a colourless liquid boiling at 165° to 166°, and having a 
specific gravity of 1*224 at 0°. It is quickly decomposed by 
water, with separation of arsenic trioxide.* 

' Tarini, Jnn, Chem. Pharm, cxxxvii. 121. 

• ('h'rniont, Ann, Chem Pharm, xci. 376. 

* C'lrnnont, Huil. Soc, Chitn, [2], viii. 206; xiv. j)9 



ARSENITES, ARSENATES, BORATES OF ETHYL. 367 



Ethyl Arsenate, [C^^^PisO^, is obtaiQed by heating silver 
arsenate to lOO** with the calculated quantity of iodide of ethyl 
diluted with ether. It is a colourless liquid, which boils under 
the ordinary atmospheric pressure, with slight decomposition at 
235** to 238**, but may be distilled in a vacuum without de- 
composition. It dissolves in water with decomposition, the 
solution yielding all the reactions of arsenic acid.^ 

Ethyl Orthoborate, (02115)3603, was discovered by Ebelmen in 
1845, and investigated by this chemist and Bouquet. They 
obtained it by saturating alcohol with gaseous boron trifluoride.^ 
These experiments were afterwards corroborated by Bowman,* 
and H. Rose noticed that ethyl borate could also be easily pre- 
pared by distilling a mixture of two parts of anhydrous borax 
and three parts of potassium ethyl sulphate.* Frankland em- 
ployed this reaction in his investigation on the organic com- 
pounds containing boron,^ and found that from the distillate, 
which contains a large quantity of alcohol, ethyl borate could 
be best separated by the addition of one-fourth part its weight 
of fused calcium chloride ; after this has dissolved, two layers of 
liquid make their appearance, of which the upper one contains 
the whole of the ethereal salt, and this can be purified by 
fractional distillation. It also is formed by heating boron trioxide 
with alcohol for some time to 120°, and may be readily obtained 
from the portion of the distillate coming over above 100°, by 
addition of a small quantity of sulphuric acid. 

Ethyl borate is a thin colourless liquid boiling at 120*", having 
a specific gravity of 8C1 at 2G°'5, a vapour density of 514, 
ivnd burning with a green flame. It has a peculiar pleasant 
smell and a hot bitter taste. It is easily decomposed by water, 
with separation of boric acid. When heated with boric trioxide, 
ethyl meiahoi^ate, (02115)2620^, is formed as a thick colourless 
liquid, converted at 200° into orthoborate and ethyl triborate, 
C2H5B3O5. This latter is a gummy mass, which, like the other 
borates is decomposed by water, with separation of boric acid.^ 

* Clermont, Bull. Soe. Chim. [2], viii. 206 ; xiv. 99. 
^ Ann. Chim. Phys. [3], xvii. 55. 

3 Phil, Mag. [3], xxix. 546. 

* Pogg. Ann. xcviii. 245. 

« Ann, Chem, Pharm. cxxiv. 129; Phil. Trans. 1862, 167. 

* Schiir, Ann, Chem, Phann. Suppl. v, 164. 



378 THE ETHYL GROUP. 



SULPHUR COMPOUNDS OF ETHYL. 

246 Ethyl ffydrosiUphide or Ethyl Mercaptan, CgH^JSH. This 
compound was obtained by Zeise in 1833 by distilling caldom 
ethyl sulphate with a solution of barium hydrosulphide : 

CaCSO.CjHg), + Ba(SH)2 = 2 C,HySH + CaSO, + BaSO,. 

Mercaptan, as Zeise named this substance, is also formed when 
an alcoholic solution of potassium hydrosulphide is saturated 
with ethyl chloride and then the product distilled, the current of 
ethyl chloride being continued.^ According to Liebig,* it is 
best obtained by saturating caustic potash of specific gravi^ 
IS with sulphuretted hydrogen, adding an equal volume of a 
solution of calcium ethyl sulphate of the same specific gravity 
and distilling. It is likewise easily obtained by acting with 
phosphorus pentasulphide on alcohol.^ For other methods of 
preparing mercaptan the original memoirs may be consulted.* 

In order to purify the crude product it is first separated from 
water, dried over chloride of calcium, and distilled. The first 
portions passing over consist of almost pure mercaptan, whilst a 
quantity of ethyl disulphide formed at the same time remains 
behind. This latter substance is not formed when the mercaptan 
is prepared according to Regnault's method. 

In order to free it from sulphuretted hydrogen, which is 
difiicult to remove, it is best to rectify it over mercury mercap- 
tide. It may also be obtained in the pure state by the decom- 
position of this same compound, a description of which will be 
found in the sequel (Zeise). 

Ethyl hydrosulphide is a colourless liquid having a penetrating 
garlic-like smell, and unpleasant taste. It boils at 36**2, has at 
21** a specific gravity of 0835, and possesses a vapour density 
of 2" 188 (Rcgnault). A drop solidifies on a glass rod exposed 
to a current of air, yielding a white mass which soon melts and 
evaporates (Liebig). When mixed with water, and the mixture 
cooled to + 2°, crystals are formed which melt again at 12', 
decomposing into mercaptan and water. ^ The.se jwssess the 
composition CjHgS + I8H2O (Clae.sson). Mercaptan forms 

* Regnault, Ann. Chim, Phys. [2], Ixxi. 8ftO. 
' Ann, Pharm, xi. 14. 

' Kekale, Ann. Chtm. Pharm. xc, 810. 

* Sace, Ann. Chcm. Pharm. li. 348 ; E. Kof.p, ih. Ixiv. 320 ; Delui^ fh. Ixxii. 
18 ; Ixxv. 121 ; Carius. ih. ixii. 190 ; Schiff, ib, oxviii. J>0. 

» H. Miillcr, Arch. Pharm. [2J, cl. 147, 



ETHYL MERCAPTAN. 379 



two compounds with titanium chloride, of which the first, 
TiCl^ -I- CgHgS, is deposited in blackish-red crystals, whilst the 
other, TiCl4 + 2CjHgS, has a bright scarlet-red colour, and 
crystallizes well.^ Mercaptan is easily inflammable, burning with 
a blue sulphur-like flame. Nitric oxide is quickly absorbed by 
this substance giving rise to a dark blood-red solution. Ethyl mer- 
captan, both in the pure state and in solution in water, possesses 
a neutral reaction. The hydrogen which is combined with the 
sulphur may readily be replaced by metals with formation of 
compounds termed mercaptides. 

Potassium Mercaptide, CgH^SK, is formed with evolution of 
hydrogen, when potassium is dissolved in mercaptan; and it 
remains behind, when the excess of the volatile liquid is evapo- 
rated, in the form of a granular mass, which, when heated, 
undergoes decomposition. 

The sodium compound, prepared in a similar way, forms a 
snow-like mass.^ 

Lead Mercaptide, (C2H5S)2Pb, is thrown down on mixing 
idcoholic solutions of mercaptan and lead acetate as a yellow 
crystalline precipitate, which dissolves in an excess of lead ace- 
tate and crystallizes from solution in needles. It is unaltered 
by caustic potash. 

Capper Mercaptide, (C2H5S)2Cu, is a pale yellow precipitate 
obtained when a solution of potassium mercaptide is brought in 
contact with one of copper sulphate. 

Silver Mercaptide, Cg^^S Ag. Mercaptan acts upon silver oxide 
so violently, even when it is diluted with alcohol, that ignition 
may take place. Mercaptan produces a snow-white precipitate 
in solution of silver nitrate, but this precipitate appears always 
to contain nitric acid. 

Mercuric Mercaptide, (C2H5S)2Hg. Mercaptan acts violently, 
with evolution of heat, on solutions of mercuric salts yielding 
a precipitate of the above compound. In order to prepare it, 
mercury oxide is added in small quantities to ethyl hydrosul- 
phide well cooled with ice, and the mass thus obtained 
recrystallized from boiling alcohol. Glistening, colourless, 
transparent tablets are obtained, which melt at 80°, and then 
solidify to a solid mass. This compound is decomposed above 
130® with formation cf vapours which attack the eyes power- 
fully. It dissolves in concentrated hydrochloric acid without 

^ Demaryav, BuU. Soc. Chim, [2], xx. 127. 

2 Claes»on,' Bull Soc. Chiia, [2], xxv. 184 ; Joarn, Frakt, Chem. [2], xv. 193. 



380 THE ETHYL GROUP. 



decomposition, and on cooling the dilute boiling acid, it separates 
out in glistening crystals. It is also unattacked by caustic 
potash. It forms a difficultly soluble compound with meivaiic 
cliloride (C2H5S)2Hg + HgClj, obtained in the form of glistening 
tablets from boiling alcoholic solution. 

Bismuth Afercaptide, (CgH^S^jBi, is obtained by the actkm 
of bismuth nitrate, and crystallizes in elastic yellow needles 
easily soluble in acids and alcohol, and precipitated when the 
acid solution is neutralized (Claesson). 

Gold Mercaptide, CgH^SAu. Mercaptan does not act upou 
gold oxide so violently as upon silver oxide. If dilute aqueous 
solutions of aur'c chloride and mercaptan are mixed, a semi- 
solid mass of aurous mercaptide is formed, the chlorine which is 
evolved decomposing a portion of the mercaptan. This com- 
pound, when dried, forms a light amorphous mass resembling 
aluminium hydroxide. 

Platinum Mercaptide, (C2H5S)2Pt, is a pale yellow precipitate, 
which on exposure to air becomes heated nearly to incandescence, 
leaving a black residue of sulphide of platinum. 



Ethyl Sulphide, {C^^^. 

247 This was first obtained in 1833 by Dobereiner,' and 
afterwards more fully examined by Regnault.* In order to 
obtain it, gaseous ethyl chloride is passed into an alcoholic 
solution of potassium hydrosulphide, and the operation conducted 
exactly as described under methyl sulphide. It may also be 
easily prepared by distilling an alcoholic solution of potassium 
monosulphide with potassium ethyl sulphate.^ It is further 
obtained by the action of phosphorus pentasulphide on ether,* 
and, together with mercaptan, when the pentasulphide is 
allowed to act upon alcohol. The metallic sulphides, which 
are decomposed by hydrochloric acid, also yield this compound 
when they are heated with the haloid ethyl ethers,* and some 
ethyl sulphide is likewise formed when these sulphides are 
brought together with a mixture of hydrochloric acid and 
alcohol.* 

' Srhurifjij, J^urn, Jxi. 377. 

* Ann. Chim. PKyn. [2J, Ixxi. 387. 

* Holwon, Quart, Joum, Chin. Hfc. x. 56, 

* RGckmanii, Journ, Prali, Chem. [2], xvii. 4M. 
" Kei^iiault, /or. eit. 

* Loir, Jnn, Chim, Phtfn. [3], xxxix 441 ; liv. 42. 



ETHYL SULPHIDE. 381 



To prepare pure ethyl sulphide the crude liquid is washed 
with water, dried over chloride of calcium, or, better, over 
phosphorus pentoxide, and then carefully distilled. It is a 
colourless liquid, having a strong garlic-like smell, but some- 
what less unpleasant than mercaptan. At 0° its specific gravity 
is 0*8367 ; it boils at 92**,^ and its vapour has a density of 3*10. 
(Regnault.) 

If chlorine be passed into cold ethyl sulphide in the dark, 
substitution-products are formed, which have been investigated 
by Regnault* and Riche.^ Ethyl sulphide also combines with 
many metallic chlorides and iodides.* 

Ethyl StUphide Mercuric Chloride, {C^Ii^^S,lIgC\2, is obtained 
as a white crystalline mass, when an aqueous solution of corro- 
sive sublimate is shaken up with ethyl sulphide. It is soluble 
in alcohol and ether, and crystallizes from solution in the latter 
solvent in fine monoclinic prisms melting at 90°, and possessing 
an aromatic smell. These lose ethyl sulphide on exposure to 
air, alid become opaque. 

£thyl Sulphide Mercuric Iodide, (03115)28. Hgig, is formed by 
heating the foregoing compound, or mercuric sulphide, with 
alcohol and ethyl iodide to 100° for several' hours. It is depo- 
sited in yellow needles soluble in alcohol and ether, melting at 
110** and decomposing at 180°. 

Ethyl Sidphide Titanium Chloride, 2(C2H5)2S.TiCl^, forms fine 
dark-red crystals. Another compound of a similar constitution 
is known, which does not crystallize well, and has a rose-red 
colour, (02^5)2^ + TiCl, (Demar(;ay). 

Ethyl Sulphide Platinum Chloride, SCCaHJgS.PtCl^, is ob- 
tained in a similar way to the mercury compound, and 
crystallizes in yellow needles. 

Ethyl Methyl Sulphide, 03115(0113)8, was first obtained by 
Carius^ by heating ethyl dithiophosphate with methyl alcohol 
to 150*. It is also formed when the alcoholic solution of 
sodium ethyl mercaptide is heated with methyl iodide.^ This 
compound is a disagreeably smelling liquid boiling at 68°, and 
forming a crystalline compound with mercuric chloride. 

« Beckmann, loc. at. « Ann. Chirn, Phys [2], Ixxi. 387. 

' lb. [3], xliii 2S3 * Loir, loc, cii, 

* Ann. Chem, Pharm. cxix 313. 

• Kruger. Journ Prakt. Oicm. [2], xiv. 206 



382 THE ETHYL GROUP. 



Ethylsulphine Compounds. 

248 Diethylsulphine Compounds. When ethyl sulphide is 
added drop by drop to well-cooled nitric acid of specific gravity 
12 it dissolves, and forms a nitrate corresponding to the methyl 
compound. This is a thick liquid. The compound has not been 
obtained in the pure state. By the action of barium carbonate 
on its aqueous solution, diethylsulphine oxide, {fi^^^O, is 
obtained. 

This is a thick colourless liquid soluble in water, alcohol and 
ether, which on cooling yields a crystalline mass, and decomposes 
on heating.^ When treated with hydriodic acid, or with adnc 
and sulphuric acid, it is reduced to ethyl sulphide, and when 
warmed with fuming nitric acid it is partially converted into 
diethylsulphoiie, (02115)2802. This latter compound may be 
obtained in the pure state by shaking ethyl sulphide with a 
solution of potassium permanganate.* It forms rhombic tables 
soluble in water and alcohol, melting at 72^, and subliming at 
100"*, though not boiling till 248°.^ On treatment with zinc and 
sulphuric acid it remains unaltered, and is likewise unacted upon 
by hydriodic acid and phosphorus pentacliloride (Beckmann). 

Triethylsulphine Compounds. These bodies were discovered 
by Oefele,^ and afterwards investigated more carefully by Dehn* 
and Cahours.* The iodide is easily formed by heating ethyl 
sulphide with ethyl iodide. 

Triethylsulphine Hydroxide, (02115)38011, is obtained by the 
action of freshly precipitated silver oxide on an aqueous solution 
of the iodide. The solution when dried in an exsiccator leaves 
a crystalline extremely deliquescent mass. This possesses a 
strongly alkaline reaction, attacks the skin like caustic potash, 
decomposes ammoniacal salts, precipitates the solutions of 
metals, and dissolves aluminium hydroxide. 

Triethylsulphine Chloride, (02115)3801, is obtained from the 
hydroxide by saturation with hydrochloric acid. It crystallizes 
in deliquescent needles difficultly soluble in alcohol, and com- 
bines with a number of metallic chlorides to form double salts 
such as 2(03115)3801 + PtOl^. This latter is deposited from 
solution in hot water in yellowish-red monoclinic prisms. 

> Beckmann, Joum. Praki, CTtem, [2], xvii 452. 

* Oefele, Ann, Chtm. Pharm. cxxWi. 370 ; cxxxU. 82. 

» lb. cxxxii. 88. * Loe. cU, 

» Ahh. Ch£m. Phann, Suppl. iv. 85. • Ann, Chim. Phtft. [5], x. 18. 



ETHYL SULPHINB COMPOUNDS. 383 



Triethyhulphiru Bromide, (C2H^)3SBr, is obtained on heating 
ethyl bromide with ethyl sulphide to a temperature of 130** — 
140^ It forms colourless rhombic crystials, easily soluble in 
water and difficultly soluble in alcohol. 

Triethylsulphine Iodide, (€2115)381, is easily formed by heat- 
ing ethyl sulphide with ethyl iodide in a flask connected with 
an inverted condenser. It is easily soluble in water and boiling 
alcohol, and crystallizes in colourless and odourless rhombic 
crystals which have a disagreeable taste. 

TriUhylsulphine Nitraie, (C2H5)3SN03, is obtained by decom- 
posing the iodide with silver nitrate. It crystallizes in extremely 
deliquescent needles, and forms with silver nitrate the double 
salt {G^^^l^O^ + AgN03. This latter compound crystallizes 
in tablets difficultly soluble in alcohol. 

Triethylsulphine Sulphate, [(C2H5)8S]2SO^, crystallizes imper- 
fectly and is easily soluble in water, but dissolves with difficulty 
in alcohol. 

Triethylsulphine Cyanide, (CgHgjgSCN, is obtained by heating 
a solution of the iodide with silver cyanide, and forms, on con- 
centration, a thick syrup, which on long standing in the 
exsiccator yields deliquescent needles. Caustic potash decom- 
poses it into ethyl sulphide, propionic acid, and ammonia.^ 
Several triethylsulphine salts of organic acids are known. 
JHethylmethylsulphine Compounds. When ethyl sulphide is 
heated with methyl iodide, diethylmethylsulphine iodide is 
formed. This is not crystallizable, and decomposes easily with evo- 
lution of ethyl sulphide. When its solution is heated with moist 
silver chloride the corresponding chloride is obtained, and this is 
also a very unstable compound. Its solution evaporated in a 
vacuum yields a thick sjrrup. The hydroxide obtained from the 
iodide by means of silver oxide does not crystallize, and the salts 
obtain^ by the action of acids are also mostly non-crystallizable. 
On the other hand, the chloride yields well-defined double salts. 
Diethylmethylsulphine Platinic Chloride, 2(C2H5)2CH3SC1 + 
PtCl^ crystallizes from water in bright yellow cubes, octohedrons, 
tetrahedrons, and other forms of the regular system. These on 
drying fall to a yellow powder, and they melt at 214'' with 
evolution of unpleasantly smelling vapours. 

Diethylmethylsulphine Mercuric Chloride, (C2H5)2CH3SC1 -f 
6HgCl2, forms colourless apparently hexagonal crystals which 
melt at 198°. 

1 Ciaiitre, ZeiUcK Cluim. 1868, 622. 



384 THE ETHYL GROUP. 



EthyhntthyUthyhulphine Compounds, The iodide, CsHj(CH^ 
C2H5SI, is obtained by the union of ethyl iodide and methjl 
ethyl sulphide, and crystallizes in long, very deliquescent needln^ 
and yields a non-crystalline chloride. 

Etkylmethylethylsulpkine Platinie Chloride, 2C^lL^{Ctl^ 
CgH^SCl + PtCl^, is a dark-red precipitate insoluble in alcobtd. 
It crystallizes from aqueous solution in long, apparently mono- 
clinic prisms which on drying fall to a rose-red powder, melting 
with decomposition at 186°. If crystallized frequently from 
water, or warmed for a long time on the water-bath, this com- 
pound is converted into the isomeric diethylmethyl compound, 
which, however, cannot be reconverted into the compound under 
discussion. 

Ethylmethylcthylsidphine Mercuric Chloride, C^^{j(!^H^ 
CgHgSCl -f 2HgCl2, is a difficultly soluble white precipitate 
crystallizing from hot water in rhombic tables melting at 112*. 

Besides these, other double salts belonging to both series are 
known.^ 

Ethyl-thiocarhamide Iodide, CS(NH2)2C2H5l, may be con- 
sidered in connection with the triethylsulphine compounds. It is 
obtained by heating ethyl iodide with sulphur-urea (VoL I. p. 
G54), and yields with water and silver oxide a strongly alkaline 
solution from which rhombic crystals separate on addition of 
hydrochloric acid and platinie chloride.* 

Constitution of the Sulphine Compounds. — Two explanations 
have been given respecting the constitution of the sulphine 
compounds According to one of them, these compounds are 
to be regarded as built up of two molecules, and the isomerism 
of the two groups above mentioned can in this way be readily 
explained. Moreover this explanation is in accordance with 
the fact that triethylsulphine cyanide on heating with alkalis 
acts as if it were a compound of ethyl sulphide aiid ethyl 
cyanide. 

According to the second hypothesis, these bodies arc not mole- 
cular compounds, but contain tetrad sulphur. Much may bo 
said for this view. If the iodides are heated, they do not 
decompose into the constituents from which they were obtained. 
One part volatilizes without decomposition, but the larger 
portion decomposes with formation of free iodine, hydriodic 
acid, and other products. 

* KriigtT, Journ. PnU't, C/rw. [2J, xiv. 193. 

■' ncrntbscn and Kl»n.«»«»r, Ber. IhutKh. Chem, Or». xi, 492. 



ETHYL DISULPHIDE. 386 

If the first view of their constitution he accepted, the hydr- 

ddes must he regarded as compounds of a sulphide with an 

icohol, and they, therefore, ought easily to decompose into these 

^hen heated. This, however, is not the case ; they yield, on the 

x>ntrary, various other products of decomposition, which as yet 

aave not been properly investigated. If the sulphines are 

regarded as atomic compounds, we must assume that the four 

combining units of sulphur are unsymmetricaL On this point 

the subsequent chapters on theoretical chemistry must be 

consulted. 



Ethyl Bisulphide, (G^^^\S^. 

249 This compound was obtained first by Zeise ^ by distilling 
calcium polysulphide with potassium sulphovinate, and was 
termed by him thialoL It is also formed by various other 
reactions, of which the most important theoretically is the action 
of iodine on sodium mercaptide . ^ 



+ 2 Nal 



Ethyl disulphide is also formed when mercaptan is heated for 
six hours at ISO"* with the requisite quantity of sulphur :^ 

2 CjH,SH + S, = {C,ll,)^S, + SH,. 

In order to prepare it a mixture of 2 parts of potassium disul- 
phide, 3 parts of potassium ethyl sulphate, and 5 parts of water 
are distilled, water being added from time to time so long as 
any oily drops are carried over. It is a colourless liquid having 
a strong garlic-like smell, boiling at 151"*, and possessing a 
vapour density of 4*270 (Cahours). When heated with dilute 
nitric acid it forms diethyl-disuljyJiO'dioxidc, (0.2115)28202, a 
body which is the first oxidation-product of mercaptan, and is a 
colourless oily liquid possessing a penetrating smell and volati- 
lizing in presence of aqueous vapour, (\austic potash decomposes 
it into ethyl disulphide, ethyl sulphonicacid, and ethyl sulphinic 
acid * (pars. 254-5), and if it be treated with zinc-ilust and water 

* Ann. Pharm. xi, 1. 

* KekuU and LiDncmann, Amu Cliem. Pharm, cxxiii. 273. 
^ M. Muller, Jaum. l*rakt. Ckem. [2], iv. 39. 

* Pauly and Otto, Ber. DeutHch. rhem. Grs. xi. 2073. 

VOL. III. c ( 



NaSCjH, 


SCjHj 


+ I2 


= 1 


NaSCjHj 


SCJgH^ 



38G THE ETHYL GROUP. 

the zinc compound of mercaptan and ethyl sulphinic add ve 

obtained : 

2 ^*2»sO } S + 2Zn - (C,H,S)^ + (C^jSO,)^ 
Ethyl Tliiomljyhuric Acid, SOj •{ en tt » is J^o* known in the 

V So 

free state, but salts of this acid are known. The sodium com- 
pound, SoOgNaCgHj, is obtained by heating ethyl bromide with 
an aqueous solution of sodium thiosulphate. It crystallizes in 
thin six-sided tablets, and when the aqueous solution is wanned 
with hydrochloric acid, sodium sulphate and mercaptan aie 
formed : 

SO2 1 SC H "^ ^2^ ^ ^^* { OH^ "^ HS.C2H4. 

The silver and mercury salts are difficultly soluble precipitate^* 
which quickly blacken. If the sodium salt be added to barium 
chloride decomposition tiikes place in a few hours, common salt, 
barium dithionate, and ethyl disulphide being formed.* 

Ethyl Trisulphidc, (ColIJg^S' ^^ obtained by Cahours* in 
the impure state by distilling potassium trisulphide with potas- 
sium ethyl sulphate. It is also formed when the disulphide 
is heated with sulphur (M. Miiller). It is an unpleasantly 
smelling liquid which decomposes on heating, but may be 
distilled in presence of water. 

Ethyl TctrasiUjjhide, {0^11^)25^, is obtained by the action of 
sulphur chloride on mercaptan : 

2 CJTj.SH + S^Clg = (C,HJ,S, + 2 HCl. 

It is a heavy colourless oil having a most unpleasant smell and 
decomposing on heating into sulphur and the disulphide. 

Ethyl Pejiiasidphide, {CJilr^,Ji^, is f )rmed when the foregoinir 
compound is heated with sulphur to 150^ It is said tt) be an 
elastic mass, but it has not been obtained in the pure stjito.* 

Ethyl Thwphosphite, (021158)3?, is obtained by the action of 
phosphorus trichloride on mercaptan. It is a heavy oily liquid 
possessing a jx?netr:iting and unplejisant smell, and on heatlnj 
splitting up into pliospln>rus and ethyl disulphiile.^ 

^ Bunte, Ber. Dnitvh. CJinn. Orn. vii. r,4»l. 

* Hiinisav, Journ. Ch^m, Siic, xxviii. 687. 
' /;////. .SV. Cfiim. [-2]. XXV. 181. 

* riai-«son, null, SiK. ChiM. [2], xxv. IS.".. » /■■/'./. 



f 
o 



ETHYL THIOPHOSPHATES. 387 

Hthyl Tetrathiophosphate, (C2H5S)3PS, is formed by the action 
of phosphorus pentasulphide on mercaptan : 

6 HS.C2H5 + P2S5 = 2 PS(SCaH5)3 H- 3 H^S. 

It is an oily liquid having a very disagreeable smell. In small 
quantities it may be distilled undecomposed at 200°. Water 
decomposes it with formation of sulphuretted hydrogen, mer- 
captan, and ethyl thiophosphoric acid. In the preparation of 
this thio-ether, diethyltetrathiophosphoric acid, H(C2H5)2PS4, 
is formed, a body which is very unstable in the free state, 
but which forms a series of crystallizable salts.^ 

Intermediate between these thio-compounds and the phosphoric 
ethers several compounds exist containing both oxygen and 
sulphur. These, as well as the foregoing compounds, have been 
investigated by Carius, and amongst them we shall here only 
mention the normal ethers. 

Mhyl TrithiophoispJiatc, (CgH^gPSjO, is formed by heating 
mercaptan with phosphorus pentoxide : 

roH 

5 HS.C2H5 + P2O5 = POCSCgHJa -f PO ^ SCgH, H- 2 H^O. 

This compound may be separated from phosphoric acid and from 
ethyl dithiophosphoric acid, which are formed at the same time, 
by means of water. Ethyl trithiophosphate is an oily liquid, 
which has a peculiar alliaceous smell, and decomposes with 
violence on heating to loO"*, ether, ethyl sulphide, and ethyl 
disulphide being evolved, and an unpleasantly smelling mass 
containing phosphoric acid remaining behind. Water decomposes 
this compound with formation of ethyl thiophosphoric acid. 

£thyl Dithiopho^hate, (CgHJgPSgOg, is formed by the action 
of phosphorus pentasulphide on alcohol : 

5 HO.C2H5 + PjS, = PO-5 odjH, + PO J Oil % HjO -[. SHj 



( SCgHg ( SCgHg. 



Ethyl dithiophosphoric acid, formed at the same time, is also 
obtained (as has been stated) when mercaptan is brought in 
contact with phosphorus pentoxide. It might have been ex- 
pected that in these two distinct reactions isomeric compounds 
would have been produced, of which the one would contain the 

^ Carins, Ann. Chem. Pharrti. cxix. 289. 

C 



388 THE ETHYL GROUP. 



radical phosphoryl, PO, and the other the radical thiophos- 
phoryl, PS ; tliis, however, is not the case, either in this or other 
similar reactions. 

Ethyl dithiophosphate is a colourless oily liquid possessing a 
faint garlic-like smelL When heated or placed in contact with 
water it acts like the foregoing compound. When heated with 
sulphuric acid eihyl perUathiqpha8pfuite,{C fi^S)^O.S.'PO{SCfi^^ 
is formed. This compound yields large monoclinic crystals 
having a fatty lustre melts at Tl''^, and possesses on warming 
an unpleasant smell. 

Mhyl Monothtophosphate, {C^^^^O^ is obtained by heating 
thiophosphoryl chloride with absolute alcohol. It is a colourless 
not unpleasantly-smelling oil, which can be distilled without 
alteration in a current of carbon dioxide. This same compound 
was obtained by Chevrier ^ by acting on phosphorus thiochloride 
by sodium ethylate. It also has an unpleasant smell like decom- 
posing turnips. On boiling this with water, ethyl monothio- 
phosphoric acid, H(C2H5)2PS03, is formed, and this body may 
be obtained in the same way with evolution of sulphuretted 
hydrogen from dithiophosphoric acid. If a salt of ethyl mono- 
thiophosphoric acid be warmed with phosphorus oxychloride, 
an oily, slightly smelling liquid, ethyl dithiopyrophosphate 

Ethyl Thioarsenite, (C2HgS)3As, is formed by the action of 
sodium mercaptide on arsenic trichloride diluted with ether. 
It is a heavy, oily, very unpleasantly smelling liquid, which on 
heating decomposes into arsenic and ethyl sulphide.* 

Uthyl Tf-ithiocarboneUe, (C2HgS)2CS. This compound was 
discovered by Sclnveizer' in 1844, and obtained by acting upon 
ethyl chloride with potassium thiocarbonate. It was more care- 
fully investigated by Debus.* According to Huscmann,* it is 
best prepared by shaking up sodium thiocarbonate with two to 
three times its weight of alcohol, and rather less than the 
e(iuivalent quantity of ethyl iodide. A reaction then occurs 
witlj considerable evolution of heat. In place of the iodide, 
bromide of ethyl may also be employed,® 

> Bull Soe. Chim, [21. xii. 372. 

« Clacsson, Bull, Soe. Chim. [2], xxv. 185. 

' Junm. Ihrakt, Chrm, xxxii. 54. 

^ Ann. Chem. Pharm. Ixxv. 147. 

* Ann. Chrm, Pharm. cxxiii. 66 

• Suloiiion, Jtwrn. Prakt. Chan. [2], vi 433. 



XANTHIC ACID. 389 



Sulphocarbonate of ethyl, as this compound was formerly 
called, is a yellow liquid possessing an alliaceous smell and a 
pleasant sweetish taste, resembling anise. It is scarcely soluble 
in water, and boils at 240°. Ammonia decomposes it with 
formation of ethyl mercaptan and ammonium thiocyanate. 

£ihyl Orthotetrathiocarhonaie, C(SC2H5)^ is formed by the 
action of sodium mercaptide, CgH^SNa (page 379), on tetra- 
chlormethane, CCl^. It is a light-yellow, peculiarly smelling 
oil, which decomposes on heating.^ 

Intermediate between these ethers and the ethyl carbonates a 
series of compounds exist, which may be divided into two classes 
according as they contain the radical carboxyl, CO, or thiocar^ 
bonyl, CS.2 

Xanthic Acid, or Etuyl-Oxydithiocarbonic Acid, 

cs { gg^H. 

250 The potassium salt of this acid is easily obtained by the 
action of carbon disulphide on an alcoholic solution of potash.^ 
In order to prepare this salt a solution of caustic potash in 
absolute alcohol is mixed with an excess of carbon disulphide, 
and the crystalline mass which is soon deposited brought on to 
a filter, quickly washed with ether, and dried over sulphuric acid.* 

Potassium XantliatCy Yi{G.^^G^Jd, forms colourless silky 
needles, which become yellow on exposure to moist air. It 
possesses a peculiar faint smell and a strongly sulphurous taste. 
It is easily soluble in water, more difficultly in alcohol, and 
colours the skin yellow. When heated with water this compound 
decomposes in the following way : 

2 KCCoHJCSgO H- 2 H,0 = K^CSg -h 2 HO.C.H^ + H^S + CO.^ 

The potassium salt when treated at 0° with dilute sulphuric 
or hydrochloric acid yields xanthic acid as a heavy, colourless 
oil, which must be- quickly washed with water and dried over 
chloride of calcium, and then may be kept in a cold place with- 
out decomposition. It has a penetrating smell somewhat re- 
sembling sulphur dioxide, and a sharp penetrating astringent 
taste. On warming it decomposes into carbon disulj)hido and 

^ Claesson, Journ. Prakt. Chan. [2], xv. 193. 

2 Salomon. 16. [2], vi. 433. 

' Zeise, Schitcig. Journ. xxxvi. 1 : xliii. 100 ; r(>(jg. Ann. xxxv. 487. 

* Slice, Ann, Chcm, Pharm, li. 345. 



/ 



390 THE ETHYL GROUP. 



alcohol ; this decomposition begins at 24•^ the liquid becoming 
turbid, and at last beginning to boil with evolution of diauljAiide 
of carbon. Xanthic acid decomposes the carbonates and fonna 
a series of salts, some of which possess a very chaiacteristic 
colour, such, for instance, as the fine yellow and very staUe 
cuprous salt, (C2H5COS2)2Cuj, from which, indeed, the name 
of the acid is derived {J^avdo^. yellow). This is obtained by 
precipitating the potassium salt, best in alcoholic solution, by 
means of cupric chloride, when a blackish-brown precipitate 
falls, consisting probably of the cupric salt, and this soon changes 
into fine yellow flocks and other products. 

Amongst other salts the following may be described : 

Ammonium XanthatCy G^^i^^^CO^^ can be obtained by 
double decomposition w^ith other salts, or by satmrating the 
free acid with ammonia. The solution yields, on evapora- 
tion in a vacuum, glistening crystals, resembling those of urea, 
which easily decompose and volatilize in a current of steam 
(Debus). 

Lead Xanthate, (C2H5.COS2)2Pb, is a crystalline precipitate 
insoluble in cold water. 

Ferric Xanthate, {CM^.CO^^^q^, is obtained by boiling 
ferric chloride with a potassium salt and carbon disulphide. It 
forms largo regular glistening black monoclinic crystals, of which 
the smallest quantity imparts to carbon disulphide a very deep 
colour. 

The chromic salt which can be prepared in a similar way 
from the violet chromic chloride, forms dark-blue glistening 
crystals which dissolve in carbon disulphide, imparting to the 
liquid a violet-blue colour. 

Arnenic Xanthate, {Q^^CO^^^PiS, is formed by the action of 
arsenic trichloride on the potassium salt. It forms large thick 
monoclinic tables without colour and odour, which melt easily, 
and on cooling yield a crystalline mass. 

The antimony salt may bo prepared in a similar way. It is 
dejiosited in large glistening, bright-yellow crystals, whilst the 
bismuth salt crystallizes in bright golden-yellow tables.^ 

Ethyl Xanthatc, or Ethyl Oxymlphocarhonatc, Csi^^^'^'is 

obtained by the action of ethyl chloride, or better of ethyl 
bromide, on the ]>otassium salt. It is a colourless liquid boiling at 
£00^ and possesses a strong unpleasant smell and a sweetish ta^te. 

^ llliuiwotz, Ann, Chem, Pharm, cxxii. 87. 



ETHYL XANTHATE. 891 



By the action of ammooia it is transformed into xanthamide or ethyl 

monothiocarbamide, CS < ^p Vr , a body crystallizing in modified 

monoclinic pyramids, which melt at SC", and are easily soluble 
in alcohol, but dissolve with greater diflficulty in water, and on 
heating are converted into mercaptan and hydrocyanic acid. By 
the action of nitrogen trioxide in presence of water this body is 
converted into the compound (Cfi^fi^^^i^* *^ which Debus 
has given the name of (xci/'SulpfiocyaniC'Cthyl-oxide.^ It crystal- 
lizes in thin white prisms, which melt at 100'', and on boiling 
with baryta-water form barium carbonate, ammonia, sulphur, 
and alcohol 

JCanthic I>i8vJphide, 02028^(02115)2. This compound was dis- 
covered by Desains * and examined by Debus,* who termed it 
ethyl bioxysulphocarbonate. It is formed by the action of 
chlorine or iodine on the xanthates according to the following 
equation : ^ 



OC,H, 
CS 




OC.H^ 
CS 


\k 




\ 

s 


+ 

SK 


I2 


+ 

s 


ci 




& 


^C^, 




^C,H,. 



2KI. 



Xanthic disulphide is insoluble in water, crystalliziDg from 
alcohol in glistening white prisms, which do not smell un- 
pleasantly, possess a biting taste, and melt at 28°. When heated 
to 210* they decompose into sulphur, carbon monoxide, carbon 
disulphide, ethyl xanthate, and the following compound. 

Ethyl Dioxythiocarbanate, 0S(002H5)2, is a pleasantly smelling, 
strongly refracting liquid, boiling at 160°, and converted by 
ammonia into alcohol and ammonium thiocyanate : 

OS { ^^2^5 4. 2 NH3 = 2 HOO2H5 + NOS(NH,). 

251 Ethyl Monothiocarbonic Acid, 00(002H6)SH. This com- 
pound is not known in the free state, but its potassium salt is 

' Ann. Chew. Pharm. Ixxxii. 270 ; Chem. Soc. Joum. iii. 84. 

« lb. Ixiv. 325. > Ih. Ixxii. 1 ; Ixxv. 121 ; Ixxxu. 255. 

* Kekulu and Liiincmano, Ann. Chem Phann, cxxiii. 273. 



Sta THE ETHVL GirOCP. 



fonneii by the aini:>a of alcjbi>Iic piHash on ethyl y^ntKat^ 
fJjehus^, when the folio wixig peculiar acdcm oocurs : 

CS[^?A. 2KOH = CO-f^A+HO.CA + KSH. 

It is soluble in waierand alcohol, and appears to be isomoTphoos 
with potassium xanthate. Acids decompose it into alcohol, car- 
bon dioxide, acd sulphoietted hydrogen, and when its aoluticHd 
:5 bjiIe*J. alcijhol. carbonyl sulphide, potassium sulphide, and 
potasidum carbonate are formed.^ 

\^lien a 5«jlution of lead acetate is added to its solution, a white 
precipitate of lead ethyl monothiocarbonate, (COj-CjH^^jSjPhi 
is formed, and this crystallizes from hot alcohol m needles. 
Ic^iine acts up^n these salts as it does on the xanthates 
with the furmation of the ethyl ether of dithiocarbonic acid or 

fUdhi/learhoxydistdjJti'U, < c poOO'H* '^^ w acolourless^ 

strongly refracting oil, heavier than water.* 

The monosulphide, S^COj-C.HJj, corresponding to the former 
compound, was obtained by Victor Meyer by acting on ethyl 
cliL^rocarlxinate with sodium sulphide. It was termed by him 
etliyl dicarbothiunate. It is a colourless liquid, boiling about 
180\ and possessing a peculiar, but faint smelL* 

£thi/l Thio,cijcarhoivitt\ COlOC^H^iSC^Hj, is obtained by 
acting with ethyl bromide or potassium ethyl monothiocarbo- 
nate, and also when sodium mercaptide is treated with ethjrl 
chlorcarbonate : 

CO I ^['2^5 + NaSaH, = CO | g J^^s + NaCl. 

It is a colourless, strongly refracting iiquid, boiling at 156'. It 
IK)sses8es a smell like that of decaying fruit, and has an aromatic 
Uiste. Cold ammonia decomposes this compound, which is 
isomeric with ethyl dioxythiocarbonate into mercaptan and 
urethane : 

On heating with water to luir, alcohol, carbon dioxide, and 
mercaptan an; formed/ 

> TWn<U>r, Ann, Chfitu Pharm. cxiviii. 137. 

' Debus, Ann. Chan. Pharm, 

» lUr. Dfuttifh. Chcux. Oes. ii. 297. 

* ::Valomoii, Joum. Prukt. Ckem. [2], \l 433. 



ETHYL THIOCARBONATES. 893 

JEthyl JDithioxycarbonate, CO(SC2H5)2. This compound, iso- 
meric with ethyl xanthate, was discovered by Schmitt and Glutz,^ 
and obtained by the action of sulphuric acid on ethyl thio- 
cyanate, and termed by the discoverers carbonyl disulphodiethyl. 
It is also formed by the action of sodium mercaptide on 
carbonyl chloride : ^ 

CO { ^} + 2 NaS-C^Hg = CO { |§«^5 + 2 NaCl. 

In this reaction the chloride, COC^SCgHg), a liquid boiling 
at 136^ is first formed. Ethyl dithioxycarbonate is a strongly 
refracting liquid possessing a garlic-like smell, and boiling at 
196^ Ammonia decomposes this ether into mercaptan and urea. 

252 The following table exhibits the composition of the thio- 
carbonates compared with ethyl carbonate : 

Ethyl Carbonate. B.P. 

Ethyl Thioxycarbonate. B.P. Ethyl Dioxythiocarbonate. B.P. 

Ethyl Dithioxycarbonate. B.P. Ethy^i%fuh&o°nate. ^■^^ 

C0{|S«5s 196' ^^{ocfl^ 2^^" 

12 6 ^25 

Ethyl Trithiocarbonatc. B.P. 

CSJiS^H" 240° 

V 2 6 

Some similar compounds of the methyl series are also known, 
as well as others which contain both methyl and ethyl.^ 

NH. 

/ . 

253 Ethyl Thiocarhaniate, CS , is formed by the action 

of xanthic ether on ammonia : 

o.an. NH, 

CS + NH, = CS + C,H,.HS. 

\ \ 

S.C2H5 O.CgHij 

* Bcr. Vcutsch. Chem. Gcs. i. 16C. 

' Salomon, Jouni. Pra\t. Chcm. [2], vii. 252. 

' Salomon aud Mnuitz, Joum. Prakt, Chcm, [2], vili. 114. 




394 THE ETHYL GROUP. 



It is a crystalline compound, and combines with many salts 
of the heavy metals. On warming it splits up into mercaptan 
and cyanic acid, and, on boiling with alkalis^ into alcohol and 
thiocyanates. 

Ethyl TkioallophancUe, CgHjNgSgO.CjHg, is formed by the action 
of hydrochloric acid on a hot concentrated alcoholic solution of 
potassium thiocyanate, thus : 

2 CNSK + 2 HCl + CH5.OH = C0.SC2H,(NH)CS.NH^ 

Ethyl ThioallophanAte. 

Recr}'stallized from hot water and ether, this compound forms 
white needle-shaped crystals, which are odourless, possess a 
bitter taste, and melt with decomposition between 170** and 
175^1 

By the action of ammonia, in the cold, on ethyl thioallo- 
phanate the foUowmg decomposition takes place, furnishing the 
clue to the constitution of this ether : 



SCjjHg 






NH +2 NH. 


NH, 

= do + 


CS + 


/ 
CS.NH, 


\h. 


^Hy 



4" HS.CoHj 



8**6 



Ethyl Sulphonic Aero, (CjHJSOjH. 

254 This was discovered by Lowig and Weidmann* in 1839, 
and prepared by the oxidation of ethyl mercaptan with nitric 
acid. It was aften\'ard8 more fully investigated by H. Kopp.* 
It is also formed by the oxidation of ethyl disulphide, as well as 
of the higher sulphides of ethyl, and also of ethyl thiocyanate.* 

In order to prepare it, liver of sulphur, obtained by fusing 
potashes with sulphur, is distilled with solution of potassium 
ethyl sulphate, and the impure disulphide thus obtained oxi- 
dized with an equal volume of nitric acid.* This reaction is 
best carried out in a retort of which the neck is placed in an 
upward position and connected with the lower part of an in- 
verted condenser The reaction is, to begin with, extremely 

* Blankenhoni, Joum.. Pntlct. Chem, [21, xvi 358. 

* Pitijij Ann. xlvii. 153; xlix. 329 ; Li>wi;r, An%, Chtm. Pharm. Ixxv 349. 
^ Ann. Chcm. Phami. xxxv. 343. * Muspratt, CKem, Sue. Joum, i. 45. 
'" M. Miiller. Journ, J'rukL C/um. [2], iv 39. 



ETHYL SULPHOXIC ACID. 396 

violent, but afterwards it must be aided by warmth, and lastly, 
the mass must be gently boiled until it is all dissolved. The 
product is heated on a water-bath, to drive off nitric acid, until 
it possesses a syrupy consistency. The residue is dissolved in 
water, and neutralized with lead carbonate in order to separate 
the excess of sulphuric acid formed. The amount of this, how- 
ever, if the sulphuric acid be not too strong, is not large. The 
filtered solution is then evaporated, and the ethyl sulphonic 
acid is thus obtained as an oily liquid of specific gravity 1'3, 
and crystallizing in the cold. It rapidly absorbs water from the 
air, is odourless, has a strong acid taste, and on heating to a 
high temperature decomposes with evolution of vapours of 
sulphuric acid and sulphur dioxide. 

Ethyl Sidphonic Chloride, C2H5SO2CI, was discovered by 
Gerhardt and Chancel,^ ^^nd is formed by the action of 
phosphorus oxycliloride or phosphorus pentachloride on ethyl 
Bulphonate : 

2 SO2 1 ^^^ + 2 PCI5 = 2 SO J §^«4- 2 NaCl + 2 POCly 

It is a colourless liquid, smelling like mustard-oil, boiling at 
l7T'o,^ and having a specific gravity of 1*357 at 22'''5. It 
fumes slightly in the air, and is slowly decomposed by water 
with formation of ethyl sulphonic acid and hydrochloric acid. 
Nascent hydrogen converts it into mercaptan.^ When heated 
with phosphorus pentachloride to 120^ phosphorus oxychloride, 
ethyl chloride, and thionyl chloride are formed : 



SO 



fan 



2 1 qI "« + PCI5 = POCI3 + C^H.Cl H- SOCI2. 

When kept for any length of time it decomposes into sulphur 
dioxide and ethyl chloride.* 

Ethyl sulphonic acid forms a series of stable Siilts, oLtaiued 
by neutralizing the free acid with an oxide, as well as by other 
methods. 

Potassiiim Ethyl Sulphoiiatc, C2H5SO3K -|- HgO, crystallizes 
in hygroscopic tablets, which lose water on heating, melt at 
120°, and on cooling yield the anhydrous salt in the form of a 
crystalline mass. If it be more strongly heated it becomes 

* C(mipL Jknd. xxxv. fiOO. ' Carius, Jaum, Prakt, Chevi. [2], ii. 262. 

* Vojrt, Ann. C%m. Ph/tnn. cxix, 152; Kndemann, ib, cxI. 333. 

* Carius, Ann. Chcm. riuirm. cxi. 93 ; cxiv. 140, 



396 THE ETHYL GROUP. 



■^ 



brown, evolves unpleasantly smelling vapours, and leaves a 
residue of potassium sulphide. 

Sodium Ethyl SulpJumate, CgHgSOjNa, resembles the potas- 
sium salt, and is very deliquescent It contains water of 
crystallization which it loses at 100°, and when a concentrated 
solution of sodium sulphite is heated with ethyl iodide to from 
ISO** to 150", the double salt 4C2H5S05Na + Nal is formed. 
This crystallizes from alcohol in silky needles.^ 

Avimoiiium Ethyl Sulphonaie, CgHgSOjNH^, is a crystalline 
deliquescent mass, obtained by boiling ethyl iodide with a 
solution of ammonium sulphite. This reaction is well suited 
for the preparation of ethyl sulphonic acid. The product of this 
reaction is boiled with lead oxide as long as ammonia is evolved, 
and the solution filtered and decomposed with sulphuretted 
hydrogen.'^ 

Barium Ethyl Sulphonaie, (C2H5S03)jBa + H^O, crystallizes 
in oblique rhombic tables which effloresce readily, and have an 
unpleasant taste. 

Lead Ethyl Sulphoiiate^ (C2H5S08)2Pb+H20, is soluble in 
water and alcohol, crystallizing from hot aqueous solution in 
tablets. 

Silver Ethyl Salplwnate, CgH^SOjAg, crystallizes from hot 
water in scales. It is also soluble in alcohol, melts when 
warmed, and may be heated to a tolerably high temperature 
without undergoing change. 

Besides these, various other ethyl sulphonates have been 
prei)ared. 

Methyl-Ethyl Sulplionate, C2H5SO3CH3, is obtiined by acting 
on ethyl sulphonic chloride with sodium methylate. It is a 
colourless, slightly smelling liquid boiling between 197° 5 to 
200°-5. 

Diethyl Sulpkoiiatey or Ethyl Sulphonic Ethyl Ether, 
C2H5SO3.C0H5, is prepared in an analogous way to the fore- 
going compound, and has a smell not unlike its isomeridc, ethyl 
sulpliitc.'* It is also formed when ethyl iodide is allowed to 
act on silver sulphite.* It boils at 213°. 

255 Ethyl Sulphinic Acid, CgH^SOj;!!. By the action of sul- 
phur dioxide on zinc ethyl Hobson * obtained the zinc compound 
of an acid to which he gave the name of ethyl trithiouic acid, 

* [kndcr, Ann. Chrm. Pharm. oxlviii. 90. ' lleniilian, 1^. clxviii. 145. 

=» Carins Journ. PrakL Chnn, [2], ii. 262. 

* Kurbatow, Bcr. Dculxh, Chem, 6«. vi. 197. * Chctn, Sue Jonrn. x. 58. 



ETHYL SELENIDE. 397 



and, according to his analyses, it possessed the formula, CgH^SgOg. 
Neither Wischin^ nor Zuckschwerdt ^ could obtain this com- 
pound, bnt when the experimental conditions were somewhat 
altered, zinc ethyl sulphinate, (C2H5S02)2Zn, was obtained. 

This is difficultly soluble in water, and may be obtained in 
soft pearly scales from alcoholic solution. The same salt is also 
formed when ethyl sulphonic chloride is brought in contact with 
zinc-dust and water.^ By decomposing with baryta-water 
barium ethyl sulphinate, (C2H5S02),Ba, may be obtained. This 
18 easily soluble in water, and on evaporation in a vacuum is 
deposited in crystals. Besides these, other crystalline com- 
pounds have been prepared. When a solution of the barium 
salt is treated with sulphuric acid ethyl svlphinic add is obtained. 
This has a pleasant sweet taste, and remains, on evaporation 
in a vacuum, as a syrupy liquid. If the acid or the zinc salt 
be oxidized with nitric acid a crystalline compound is obtained, 
together with ethyl sulphonic acid, and this crystallizes from 
hot alcohol in large glistening tablets melting at 81°*5 and which 
when carefully heated may be sublimed without decomposition. 
This body possesses the formula CgHjgSgOyN, and when boiled 
with alkalis, or heated with hydrochloric acid, it is converted 
into ethyl sulphonic acid and ammonia, some sulphuric acid 
being always formed. Hence this body is tmethyl sulphonic 
nitric oxide, (C2H5S02)3NO, which probably decomposes in 
contact with water into sulphonic acid and hydroxylamine, 
NOH3, and this latter compound acts as an oxidizing agent and 
ammonia is reduced. 



COMPOUNDS OF ETHYL AND SELENIUM. 

256 Ethyl Hydrosehnidcy CoH^SeH, was discovered by 
Siemens,* who prepared it by distilling a solution of potassium 
hydroselenide with potassium ethyl sulphate. It is a colourless 
liquid boiling below lOO*', and possessing a most unpleasant 
smell resembling that of cacodyl, which is doubtless caused by 
the presence of a small quantity of ethyl diselenide. It forms 
with mercuric oxide a yellow amorphous selenium mercaptide. 

* Ann. Chein, Pharm. cxxxlx. 364. ' Ber. Deutsch, Chem. Gen, vii. 292. 

• Fauly, Ber, Deutsch. Chcm. Ocs, x. 941. * Ann. Chcm. Pharm, Ixi. 860. 



398 THE ETHYL GROUP. 



Ethyl Sclenidc, (02115)286, was first prepared by Lowig^ in 
1830 by distilling ethyl oxalate with potassium selenide, and 
afterwards more accurately examined by Joy ^ who obtained it 
by distilling potassium ethyl sulphate with potassium selenide. 
He was, however, unable to complete his experiments owing 
to the intolerable odour which the body possesses. This, as was 
afterwards shown by Rathke,^ is due to the presence of a small 
quantity of ethyl diselenide. In order to prepare the mono- 
selenide, the best plan, according to this latter chemist, is to 
take a pure solution of caustic potash and distil it with 
potassium ethyl sulphate, to which a small quantity of selenium 
phosphate is added, which, however, must contain no free 
selenium. In this way potassium phosphate and potassium 
selenide are formed, and on distillation a mixture of mono- 
selenide and diselenide is formed, the latter being formed by 
the action of oxygen on the former compound. They may 
be then separated by fractional distillation. It is, however, 
simpler to treat the distillate again with half the quantities 
of potassium ethyl sulphate, caustic potash, and water, which 
were originally employed, and to add to this a small piece 
of ordmary sulphur. On distillation for several hours with 
a reversed condenser this compound is obtained in the pure 
state.* 

Ethyl selenide is a colourless, easily mobile, strongly re- 
fracting liquid, boiling at 108**, and having a peculiar but 
not unpleasant smell. It dissolves easily in dilute nitric acid 
with formation of the nitrate (02H5)2Se(OH)N03, which is 
decomposed on concentration. Hydrochloric acid precipitates 
ethyl selenium dichlorido, (02H5)2SeOl2, as a yellowish oil, 
slightly soluble in water, but rather more soluble in hydro- 
chloric acid. Aqueous ammonia converts it into ethyl selenium 
oxychloride, (02H5)^Se200l2, which crystallizes from alcohol in 
glistening colourless cubes, and is converted, in presence of 
hydrochloric acid, into the original compound. Hydrobromic 
acid precipitates ethyl selenium bromide, (02H5)2SeBr2, from 
solutions of the nitrate, in the form of a light yellow coloured 
soluble oil ; the iodide prepared in a similar way is a yellow 
lustrous liquid somewhat resembling bromine. 



* P<>00- -^^n. xxxvii. C/>2. 

• Ann, Chern^ Pftann. Ixxxvi. 35. 

• Anit. Cfinn. Phamu clii. 210. 

* rieverling, LUb. Ann. clxxxv. 331 ; Ber. Deutsth. Chnu, Oes. ix. 1460. 



ETHYL TELLURIDE. 399 



TrUihyl Seleniodide, (C2H5)3SeI, is fonned by the combination 
of the foregoing compound with ethyl iodide.^ It forms glistening 
Yrhite crystalline needles closely resembling Epsom salts, and very 
soluble in water. They decompose, on heating, into their consti- 
tuents which on cooling gradually again unite with one another. 
Moist silver oxide acts on the solution of this body as it does 
on the corresponding sulphine iodides. The hydroxide thus 
formed is left on evaporation in a vacuum as a syrupy liquid, 
which is as alkaline and caustic as potash. Its salts are, most 
of them, deliquescent, possessing an alliaceous smell, and having 
a bitter and burning taste. The platinichloride, (CgHJ^SegPtCl^ 
crystallizes on evaporating the hot saturated solution in glistening 
red acute rhombohedrons with basic terminal faces (Pieverling). 

Ethyl IHseknide, (02115)2862, which is formed as a by-product 
in the preparation of the above-mentioned selenium compounds, 
was first obtained by Wohler and Dean,^ mixed with some 
monoselenide, by heating potassium selenide (obtained by 
heating potassium selenite and carbon together) with potassium 
ethyl sulphate. Rathke has however shown that when a selenite 
is heated with carbon, polyselenides are formed, scarcely any 
monoselenide being produced, the reaction beginning before the 
moisture in the carbon is driven off and this then acting as an 
oxidizing agent. 

Ethyl diselenide is a heavy brownish-red oil, boiling at 180**, 
and having a frightful smell, and acting as a poison (Pieverling). 
When it is dissolved in nitric acid, and hydrochloric acid is 
added, the compound C2H5SeS02H + HCl is formed, crystallizing 
in fine monoclinic prisms (Rathke). 



COMPOUNDS OF ETHYL AND TELLURIUM. 

257 Hthyl Telluride, (Q^^^e, was first obtained in 1840 by 
Wohler' by distilling potassium telluride with barium ethyl 
sulphate. It was then prepared by Mallet,* and afterwards more 
exactly investigated by Wohler.^ In order to prepare it, one 
part of tellurium is treated with 10 parts of ignited cream of 
tartar in a porcelain retort to the neck of which a bent glass 
tube is attached. When no further evolution of carbon dioxide 
takes place, the glass tube is placed in a large flask filled with 

' Cahours, Comptcs JiCiuhis, Ix. 620. * Ann. Chcm. Pharm. xcvii. 1. 
' yinn, Chcni. Pharm, xxxv. 111. * Chan. Soc. Journ. v. 71. 

* Ann. Clicm. PJutnn. Ixxxiv. Gl), 



400 THE ETHYL GROUP. 



carbon dioxide, in order to prevent the entrance of air into the 
apparatus, and then, after the vessel has cooled, the requisite 
quantity of concentrated solution of potassium ethyl sulphate 
dissolved in water free from air is added, and the whole warmed, 
the contents of the retort being brought into a flask filled with 
carbon dioxide and the whole distilled in a current of this gaa. 
These precautions are necessary in order to prevent the oxida- 
tion of the potassium telluride, but in spite of this a quantity 
of ethyl ditelluride is usually formed, and this comes over 
towards the end of the distillation. 

Ethyl telluride is a thick red liquid boiling at 98^^ and 
yielding a deep yellow-coloured vapour. It is heavier than 
water, possesses a strong, very unpleasant smell, reminding 
one at the same time of ethyl selenide and telluretted 
hydrogen. Its vapour attacks the lungs and appears to be 
poisonous. During the whole time that Wohler was occupied 
in this investigation his breath was tainted with the un- 
pleasant smell of this compound. When a small dose of 
potassium telluride, namely, from 04 to 005 gram, is taken, 
the breath after a few minutes becomes for a length of time 
tainted with this unpleasant odour.* Ethyl telluride is easily 
inflammable, and burns with a bright blue flame evolving clouds 
of tellurium dioxide. Exposed to the air it soon becomes 
covered with a white crust, and the whole mass gradually 
changes to a white earthy solid. This oxidation occurs so 
quickly in sunlight that the liquid begins to fume, without 
however taking fire. 

Ethyl Tellurium Oxide, {Q^^^qO, has not yet been obtained 
in the pure state. Its solution, prepared by treating the chloride 
or oxychloridc with silver oxide, turns turmeric paper brown, and 
absorbs carbon dioxide from the air. On evaporation, decom- 
position occurs. When saturated with an acid, ethyl tellurium 
salts are obtained, the point of departure for which is the nitrate. 

Ethyl Tellunum NUrate, T:(i{C^^,{0^)^0^, is formed by 
dissolving ethyl telluride in nitric acid. It forms monoclinic 
crystals, which on heating deflagrate like gunpowder. 

Ethyl Tclluriuvt Chloruk, Te(C2H,)2Cl2, is obtained from the 
solution of the nitrate by the addition of concentrated hydro- 
chloric acid, when an oily licjuid is formed, possessing an un- 
pleasant smell, and volatilizing at a high temperature without 

][ Heercn. Chcm. CciUr. 1861, 916. 

- liansM.'!), Ann, Chan, Pharm. Ixxwi. 208. 



NITROGEN BASES OF ETHYL. 401 

decomposition. When it is dissolved in warm ammonia and the 
liquid allowed to evaporate, the oxychloride, Te2(C2H5)^OCl2, is 
formed in glistening six-sided prisms, which are difficultly 
soluble in water but readily so in ammonia and alcohol. 

The bromide is a light yellow oil, and the iodide an orange- 
yellow precipitate. Treated with ammonia they both yield 
crystallizable oxy-compounds. 

£thyl TeUurium Sulphate, Te2(C2H5)^(OH)2S04, is obtained by 
decomposing the oxychloride with silver sulphate, or by acting 
with lead dioxide and dilute sulphuric acid on ethyl telluride. 
It crystallizes in colourless prisms. 

Hthyl Tellurium Carbonate, Te2(C2H5)^(OH)2C03, is obtained 
by saturating the solution of the oxide with carbon dioxide, or by 
decomposing the oxychloride with silver carbonate. It forms 
small well-defined crystals. 

Various ethyl tellurium salts of organic acids are also known. 

Ethyl Ditelluride, (C2H5)oTe2, is always formed in the prepa- 
ration of the mono*«lluride ; it is a dark-red liquid having a 
high boiling point. 

Triethyl Tellurium Iodide, (C2H5)3TeI, is a crystallizable body 
obtained by the combination of ethyl iodide with ethyl telluride.i 
It crystallizes from aqueous solution in a vacuum in bright yellow 
monoclinic prisms, which melt at 90** — 02°. On distillation it 
decomposes into its constituents which after some hours unite 
together on standing (Pieverling). J3y treating the aqueous 
solution of this body with silver oxide, a liquid having an alka- 
line reaction is obtained, and this, when saturated with hydro- 
chloric acid and treated with platinum chloride, yields an 
orange-yellow crystalline precipitate of [(C2H5)3Te]2PtClg.^ 



NITROGEN BASES OF ETHYL. 

The Ethylamine Compounds. 

258 Ethylamine, NH2C2H5, was first prepared by Wurtz ^ in 
1848, by distilling ethyl isocyanurate with caustic potash, and 
Hofmann * soon afterwards obtained the other ethyl bases. 
These discoveries not only exerted a great influence on the 

' Cabours, Ball, Soc. Chim. [2], iv. 40. 

* Becker, lAehig'g Ann. clxxx. 262. 

' Comptes JRejidvSj xxviii. 22.3 ; Ann, CJiim. Phi/s [3], xxx. 443. 

* P?i)l. Trans. 1850 [1], 93; Ann. Chem. Pharm. Ixxiii. 91. 

VOL. II r. D D 



402 THE ETHYL GROUP. 



progress of theoretical chemistry but also on the industrial 
application of the science, inasmuch as by their means an 
important branch of the manufacture of aniline colours was 
called into being. In order to prepare the ethyl bases, a 
haloid salt of ethyl is heated with ammonia. The ethyl 
ethers of other inorganic acids, such for instance as the 
nitrate (Juncadella), the sulphite (Carius), the sulphate 
(Strecker), and the phosphate (Clermont), are attacked in a 
similar way by ammonia, but in all these cases the three other 
bases are formed together with the primary base.^ 

In order to prepare large quantities of these compounds, the 
method proposed by Hofmann^ is the best. For this purpose 
the crude ethyl chloride obtained as a by-product in the prepa- 
ration of chloral is employed. This contains higher substitution- 
products, but these may afterwards be readily separated. One 
part of this crude ethyl chloride is digested with three times its 
volume of spirit, containing 95 per cent, of alcohol, previously 
saturated with ammonia at 0**. For this purpose a wrought iron 
digester is usually employed, the whole being heated for an hour 
in boiling water. On cooling, the liquid deposits sal-ammoniac, 
this is filtered off, and the liquid distilled on a water-bath. The 
higher chlorinated chlorides of ethyl pass over first, and then al- 
cohol containing ammonia, which after a further saturation with 
ammonia may be used in a second preparation. As soon as the 
distillation is complete, the residue left in the retort is evapo- 
rated m a basin until all the alcohol is removed. On cooling, 
the liquid solidifies to a feathery crystalline mass of the ethyl- 
amine hydrochlorates, with which a small quantity of sal- 
ammoniac is mixed. Concentrated caustic soda is now added, 
and the liquid layer which separates out, consisting of a 
mixture of the three bases, is drawn off and dried over solid 
caustic soda. Although the boiling points of the three bases 
differ very considerably, they cannot be separated by fractional 
distillation, and in order to obtain them in the pure state a plan 
similar to that adopted in the case of the methyl compounds 
must be employed. The product is, therefore, treated with ethyl 
oxalate, when the triethylamine remains unaltered, and may 
be distilled off from the water-bath. The residue consists of a 
mixture of solid diethyloxamide, Cp,(NH.C3H5)j, and liquid 
diethyl oxamic ethyl ether, C202N(C,H5),OC,H^ which is then 

> Hofmann, Proc. Roy. Soc, xi. S6, Carer-liet, Siliim. Am. Journ, [2], xxxiL 
26 ; xxxir. • Ber. DeuUek. Ckem. Ot$, iii. 109. 



RTHYLAMINE. 403 



washed and mechanically separated, and then purified as hereafter 
described.^ Duvillier and Buisine have described a modification 
of this method of separation.^ 



Ethylamine, CgHg.NHj. 

259 In order to obtain this compound pure, diethyloxamide is 
recrystallized from hot water and then distilled with caustic 
potash : 

CjOj(NH.C2H,), -f 2 HOK = 2 NH2.C2H4 + Cj02(0K),. 

Pure ethylamine is also obtained by reducing nitroethane. 

It is a mobile liquid boiling at 18°*7, and having a specific 
gravity of 0*6964 at 8^ It possesses a strong ammoniacal smell 
and a powerful caustic taste. It is miscible in all proportions 
with water with evolution of heat, and when ignited it bums 
with a yellow flame. 

Ethylamine is also formed when sal-ammoniac and ammonium 
iodide are heated with alcohol to 400°,* as well as when sal- 
ammoniac is fused with crystallized sodium ethylate.* 

Ethylamine is so powerful a base that it decomposes ammoniacal 
salts, and, like ammonia, throws down many metallic hydroxides. 
It is, however, distinguished from ammonia by the fact that 
precipitated aluminium hydroxide redissolves in excess of 
ethylamine. This base may, therefore, be employed for the 
separation of ferric oxide and alumina.^ Other points of 
difference are that cupric hydroxide dissolves only with diflB- 
culty in excess of ethylamine, whilst the salts of cadmium, 
nickel, and cobalt yield precipitates which are insoluble in 
excess. 

Ethylamine Hydrochloride, or Ethylammonium Chloride, 
N(C2H5)H3C1, crystallizes from water in fine very deliquescent 
prisms, and from hot alcohol in tablets. Stas obtained it in 
large crystals by allowing a mixture of ethyl chloride and an 
ethereal solution of ammonia to stand for some time exposed to 
the action of the sun's rays.' According to Groves this salt is 
best obtained by heating a mixture of one volume of ethyl 

* Hofmann, Proc Roy. Soc, xi, 66 ; Ber. DcuUch. Chem. Ges. iii. 776 ; Ber. 
Berlin. Acad., 1871, 26. * Compi. Rend. IxxxviiL 81, 

3 V. Meyer, Lichigs Ann, clxxv. 88. 

* Berthelot, Ann, Chim. Phys, [3], xxxviii. 64, 

• Kiihler, Ber. Deutsch. Chem. Ges. xi. 2093. 

• E. Aleyer, Joum, Praki, Chem. Ixvii. 147. ' Kekule, Lehrbuch, i 

D I) 2 



404 THE ETHYL GROUP. 



chloride and three volumes of strong alcoholic ammonia for seven 
hours to 100^^ It melts at 76^ — 80° and on cooling solidifies to 
a crystalline mass. Heated from 315" to 320°, it evolves vapours, 
and on cooling forms a milk-white amcrphous mass melting at 
260°. It forms double salts with metallic chlorides. 

The bromide and iodide closely resemble the chloride but 
have not been more exactly described. According to Wohler 
and Diinhaupt pure ethylamine hydriodide is obtained when 
a boiling mixture of equal volumes of ethyl iodide and absolute 
alcohol is saturated with dry ammonia and then allowed to stand 
until water produces no further turbidity.* 

Ethylammonium Sulphate, (NC2H5)2HgSO^ is an uncrystalliz- 
able deliquescent mj^ss, easily soluble in alcohol. It forms double 
salts with the sulphates of magnesium, copper and aluminium. 
Aluminium ethylammonium' alum, A1^(S0^^ + (NCgHJ^H^SO^ 
+ 24H2O, crystallizes in octohedrons. 

Ethylaminmiium Nitrate crj-stallizes only with difficulty in 
very deliquescent scales. 

Ethylammonium Carbonate is obtained by distilling the anhy- 
drous chloride with dry carbonate of soda. It is obtained as 
a liquid which solidifies to a cryst-alline mass. It has a strung 
smell of ammonia and is deliquescent. Its composition closely 
corresponds to that of the normal salt. 

Ethjlammonium Carhamatc, CO < oxvfi H ^H ' ^^ ^ W'hite 

powdery mass obtained by passing dry carbon dioxide into 
ethlyamine. It is soluble in water and its solution precipitates 
calcium chloride on stan<Ung. 

Ethylammonium Cliloraiiratc, N(C2H..JH3AuCl^, is obtained 
by evaporating a solution of the hydrochloride with gold chloride, 
and crystallizes in fine golden-jellow prisms, soluble in water, 
alcohol, and ether. 

Ethylammonium Plaiinichloride, 'ifj^C^^H r^JI^T tCl^^ is formed 
as a yellow precipitate when concentmted solutions of its two 
constituents cure mixed and alcohol added. It crystiillizes from 
hot water in obtuse rhombohedrons, which were long supposed 
to be cubes (Schabus). 

riatodiethylammonium Platimchloridi\ Pt(NC.H,Ho)4PtCl^. 
This compound, which corresponds to Magnus h green salt, is a 
reddish insoluble powder, obtained by Wtirtz by acting on ethyl- 
amine with platinous chloride. When it is heated with a 

* Quart. Journ. Chrm, »St>c. xiii. 331. - Jun. Chem. Phann, Ixxxn. 371. 



ETHYLAMMONIUM SALTS. 405 

solution of ethylamine it dissolves, frequently leaving a residue 
of an insoluble black powder, and on evaporating the solution, 
fine colourless prisms of platodiethylammoniura chloride, 
Pt(NC2H5H2)^Cl2 (see Vol. II. Part 11. p. 412), are obtained. 

Corresponding palladium compounds are also known,^ and 
in addition to those already described, several other ethylamine 
salts have been investigated by E. Meyer.- 

Ethylammoniurri Hydrosuljphide is obtained by acting with 
sulphuretted hydrogen on ethylamine cooled with ice. It forms 
fine colourless crystals which become yellow-coloured on exposure 
and deliquesce. Its solution dissolves antimony sulphide. 

D-icJdorethylamine, ovEthylatcd Chloride of Nitrogen, NCgHgClg. 
This singular compound was first obtained by Wurtz,^ by 
acting with chlorine on an aqueous solution of ethylamine. 
In order to prepare it, 250 grams of bleaching powder are 
rubbed up with water to a thick paste and placed in a two-liter 
fiask, 100 grams of ethylamine hydrochloride being added in 
four portions, a strong evolution of heat occurring. The mix- 
ture is then distilled so long as oily drops pass over, and the 
product is subjected to a second treatment with bleaching 
powder. The distillate is then washed with water, shaken up 
with 50 per cent, sulphuric acid, washed with dilute caustic 
soda, dried over chloride of calcium, and fractionated.* Di- 
chlorethylamine is a strongly refracting golden-yellow liquid, 
having a highly penetrating smell resembling chlorpicrin and 
hypochlorous acid. It boils at 88°— 89°, and at 5° has a 
specific gravity of 1'2397. By the action of zinc-ethyl it is 
converted into triethylamine : 

\C2H5 ^^2^6 XCgH, \C1- 

Wlien kept. It frequently decomposes with formation of 
hydrochloric acid, sal-ammoniac, ethylamine hydrochloride, 
chloroform, acetonitril, and acetyl chloride.^ This decomposi- 
tion, however, only takes place when the body is not perfectly 
pure.® 

Di'iodoethylamine, CgH^NIg. This ethylated iodide of nitrogen 
was obtained by Wurtz, together with ethylamine hydriodide, 

' H. Muller, Ann. Chcm, Pharm, Ixxxvi. 367. 
' Joum, Prakt. Chem, Ixvii. 147 ; Ixviii. 279. ^ Compt, Bend, xi. 810, 

* Tscherniak, Ber. Deutsch. Chem. Ocs. ix, 146. » Kohler, ih, xiL 1869. 

« Tscherniak, B^, Deutsch, Cfu:m. Ges. xii 2129. 



406 THE ETHYL GROUP. 



bj treating an aqueous solution of ethylamine with iodine. It 
is a dark blue liquid which decomposes on heating with 
carbonization and evolution of iodine vapours. 

Ethyl Formamide, N < COH, is obtained by distilling an 

(h 

aqueous solution of ethylamine formate, and separates from the 
distillate on addition of potash.^ If ethylamine be brought in 
contact with chloral, a crystalline compound is formed, 
which on distillation decomposes into chloroform and ethyl 
formamide : - 



OH 





/ 


// 


CCL.CH 


CCLH + CH 


\ 


\ 


N(C,HJH 


N(C,H5)H. 



Ethyl formiimide is a thick, almost odourless liquid, boiling 
at 199'' and having a specific gravity of 0*952 at 21'' 

DiETIIYLAMINE, N(C2H^2H. 

260 Diethylamine is obtained by distilling the before-men- 
tioned ether of diethyloxamic acid with potash : 

<^A { oc^lf'^' + ^ ^^" ■ ^»^« I OK + N(C,H5).H + 

H0.C2Hg. 

In order to obtain this ether in the pure state, the cnide oil 
is cooled to 0°, poured off from the diethyl oxamide which 
separates out, and distilled, when the pure ether comes over 
at 2G0^ 

Diethylamine is a colourless liquid boiling at 57'*'5, pos- 
sessing a strongly ammoniacaJ smell, and being easily soluble 
in water. It is distinguished from ethylamine by the fact that 
copper hydroxide dissolves only very slightly in excess, whilst 
rinc hydroxide is altogether insoluble (Carey Lea). Its salts 
have been but slightly investigated. The platinichlorido, 
[^(CjHg^jHJjl^tCljj, forma large orange-red monoclinic crystals 
resembling octohedrons (Miiller, Sohabus). 

Ifilrosodicthi/laminr, ^^(CgHJjNO, was obtained by Gcuthor 

' Liniii'innnn, Wirn. Akad. B^r, 2to Abth. Ix. 44. 
s Hnfiiiann, /^*r. ikuUch, Chem, Gea. v. *J47. 



DIETHYL AMINE AND TRI ETHYL AMINK 407 

by acting on a concentrated solution of potassium nitrite with 
a perfecUy neutral solution of diethylamine hydrochloride : 



'{ 



an. + HO.NO = N^ CjH^ + ILO. 
H (NO 



This compound, to which he gave the name of nitro-diethylin, 
and which has likewise been termed diethyl-nitrosamine, is 
a yellowish oil having an aromatic smell and a burning taste, 
boiling at 177^ and having at 17°*5 a specific gravity of 0*951. 
When acted upon by hydrochloric acid in presence of water it 
dissolves, and on heating forms diethylamine hydrochloride, 
whilst nitric oxide is evolved, produced from the decomposition 
of the nitrous acid formed. Dry hydrochloric acid gas also 
converts it with evolution of nitrosyl chloride into diethylamine 
hydrochloride, and when it is treated with water and sodium 
amalgam the following reaction takes place : ^ 

2 N(C,H,)2N0 + 3 H, .= 2 NCC^H J^H^ + N^O + H,0. 

Diethyl Fonnamide, N(C2H5)2COH, is formed by distilling 
diethylamine formate, as a thick odourless liquid boiling at 
175**- 178^ and having at 19° a specific gravity of 0*908 
(liinnemann). 

Triethylamine, N(C2H5)3. 

a6i This is a colourless, oily, pleasantly smelling, strongly 
alkaline liquid, boiling at 91"*, lighter than water, and slightly 
soluble in this liquid. It precipitates many metallic salts. The 
precipitates are, however, not soluble in an excess of the reagent, 
with the exception of silver oxide, which dissolves sparingly, 
and of the aluminium and stannic hydroxides, which are readily 
soluble, in excess. 

Triethylamine Hydrochloride, N(C2H5)3HC1, is an inflammable 
substance crystallizing in feathery non-deliquescent scales 
which may be sublimed without decomposition. It forms with 
platinic chloride the compound [^(C2H5)3H]2PtClg, easily 
soluble in water, and yielding, on evaporation, large red rhombic 
crystals. 

Triethylamine Hydrobramide, 'N (0.271^^1131, forms large 
feathery crystals resembling sublimed sal-ammoniac. 

The sulphate is a very soluble salt crystallizing with diflSculty. 

^ Joum. Prakt. Chem. [2], iv. 435. 



403 THE ETHYL GROUP. 



Triethylamine Nitrate, N(C2H5)3HN03, is, according to Lea, 
uucrystallizable, whereas V. v Lang mentions that it forms 
rhombic crystals which are isomorphous with those of nitre.^ 



The Tetraethylammonium Compounds. 

262 TetraethylamTitonium Hydroxide, N(C2H5)^OH, is obtained 
by gradually adding freshly precipitated silver oxide to a weak 
warm solution of the corresponding iodide. If the filtrate be 
evaporated first on a water-bath and then in a vacuum, long 
very deliquescent needles are frequently obtained. These 
disappear on further evaporation, the compound drying up to 
a semi-solid deliquescent mass which in its reactions closely 
resembles caustic potash, with the exception that chromium 
hydroxide is insoluble in an excess of this reagent. 

When heated with ethyl iodide, alcohol is formed : 

N(C2H,),0H -h C^H.I = N(C2H^,I + G^YL,,011. 

The hydroxide when heated alone decomposes into triethyl- 
amine, ethylene, and water. 

Tetraethylammonium Chloride, li{(u^^fj\, is obtained by 
saturating the hydroxide with hydrochloric acid. It is crystal- 
line but very deliquescent, and forms with various metallic 
chlorides crystallizable double salts. 

The bromide is a very siniiliar body, uniting with bromine to 
form the tribromide, N(C2H5)^Br3, crystallizing from alcoholic 
solution in bright yellow needles which melt at 78"* without 
decomposition.^ 

Tetraethylammonium Iodide, ^[G^^^. This forms the 
starting-point for the preparation of the tetraethylammonium 
compounds, and is formed, as has already been stated, by the 
action of ethyl iodide on ammonia or on the ethylamines. If 
iodide of ethyl be mixed with triethylamine the mixture soon 
becomes hot, and, after some days, solidifies to a white crystal- 
line mass. The combination takes place more rapidly when the 
mixture is heated in sealed tubes to 100^ The iodide is 
easily soluble in water, and separates on evaporation in fine 
well-formed crystals. When heated it decomposes into ethyl 
iodide and triethylamine which distil over separately, but, on 
cooling, ngjiin unite. It is insoluble in caustic potash, and 

* Z^Uwch. r/,r„u 1867, ^05. » Marquart, Jkr. lk\U9ch. Chem, Ocs. iii. 284. 



TETRAETHYLAMMONIUM COMPOUNDS. 409 



hence separates out when caustic potash is added to iU sohition, 
without undergoing the slightest decomposition. Exposed to 
the air, tlie salt changes to the tri-iodide, ^^{C^^)^^, a fact 
first observed by Hofmann, but afterwards more exactly 
examined by Weltzien.^ This compound is also obtained by 
treating the product of the reaction of iodide of ethyl en 
ammonia with iodine. It crystallizes from hot alcohol in 
feathery needles, but is deposited from a solution in potassium 
iodide in quadratic piisms which exhibit a fine blue lustre by 
reflected light, and a reddish-brown colour by transmitted light. 
On addition of water to the mother-liquor, a brownish oil 
separates out, probably the pentaiodide. By the action of 
iodine monochloridc on tctraethylammonium chloride, the com- 
pound N(C2H5)^Cl2l is formed in fern-shaped crystals like 
sal-ammoniac.^ 

TetrcLethylammonium Chloraurate, N(C2H-)^AuCl^, is a 
lemon-yellow crystalUne precipitate deposited from solution in 
hot water. 

Tetraethylammonium Plallnuhloride, N2(C.»H5)yPtClg, is 
exactly analogous to the corresponding potassium compound, 
and crystallizes from hot water in octohedrons. 

Besides these bodies, a large number of other tetraethyl- 
ammonium salts exist. Those have been examined by Hofmann 
and by Classen.* 

Methyltricthylammonium Iodide, NCH3(C2H5)3l, is easily 
formed by the combination of methyl iodide with triethylamine. 
It is obtained in crystals which are exceedingly soluble in 
water, and which, in chemical reaction, exhibit great analogy 
with tetraethylammonium iodide.* 

Dimcthyldicihylammonium Iodide, N(CHj,)2(C2Hj2T. is formed 
by the prolonged action of ethyl iodide on dimethylamine, as 
also by acting on diethylamine w^ith methyl iodide. In its 
properties it closely resembles the other ammonium iodides. If 
the corresponding chloride be heated it decomposes into methyl 
chloride and methyldiethylamine, N(CH3)(C2HJ2.^ Hence we 

( CH3 C C2H, 

see that the salts, N \ CH, -*- C.,H,C1 and X-^ C2H: + CH.Cl 

(C2H, - • (CH3 

* Ann. Chnn. Ph/irm. l.xxxvi. 292 ; xci. 33, 
2 Tildcn, Jonrn, Chrm. Soc. [2], xix. 145. 

' Joum. Prakt, Chm. xciii. -146. 

* Hofmann. Phil Trans. 1851 (ii.) 357. 

* Meyer an«l Lecco, Antu Ckem, P/utrnt, v\xxx. 173. 



410 THE ETHYL GROUP. 



are idcDtical and cannot be considered as molecular compounds, 
one of which contains ethyl chloride and the other methyl 
chloride. Hence it also follows tJiat in all the ammonium 
compounds nitrogen acts a^ a pentad} 

Ethyl Hydrazines. 

263 These compounds (see ante, p. 161) were discovered by 
E. Fischer * and carefully investigated by him. 

Ethyl Hydrazine, CjHyNgHy Diethyl urea, COCNH.CjH^)^ 
is the starting point for this compound, being first converted by 
means of nitrogen trioxide into the nitroso-compound CON, 
(NO)(C2H5)2H. This is next treated with acetic acid and zinc 
dust, diethyl semicarbazide being formed, and this, on boiling 
with hydrochloric acid, is converted into ethyl hydrazine, carbon 
dioxide, and ethylamine : 

HN.CjH. 
CO + H,0 = COjj + HjN.CjHg + 

H,N— N. CgHg. HjN— HN.CjH^. 

As soon as the decomposition is complete, the solution is 
cooled by ice and saturated with hydrochloric acid, when hydra- 
zine hydrochloride separates out as a crystalline mass. Wlien 
concentrated caustic potash is added to the dry salt, a solution 
of the base is obtaine<l, which separates out as an oily liquid on 
the addition of powdered caustic potash. It may be completely 
dehydrated by the addition of anhydrous baryta. 

Ethyl hydrazine is a mobile colourless liquid possessing an 
ethereal slightly ammoniacal smell, and boiling at OO''^ when 
the barometer stands at 709 mm. It is very hygroscopic, and at 
the ordinary temperature possesses a high vapour-tension, and, 
for this reason, it emits thick white fumes on exposure to moist 
air. It dissolves in water and alcohol with evolution of heat ; 
it is very caustic, in a short time destroying cork and caoutchouc. 
With acids two series of salts are formed, of which the hydro- 
chloride is the only one hitherto carefully examined. The acid 

^ In pars. 34 niid 35 of Vol. I. it is stated that the elements of the nitrogen 
group arc trivHlmt, but that they possess the peculiarity of acting as pentads in 
certain coniix)un(ls. The facts a))Ove stated, as well as others, such as the existence 
of a stable nhosphonis |>entafluoride, prove that these elements do not possess a 
constant valency. The coni{K>und8 in which they arc pentads decompose more or 
less reailily into two ihdIccuIcs. 

' Lifbig a Annate)^ cxcix, *2>1. 



ETHYL HYDRAZINE& 411 



salty C2H5.N2H3(C1H)2, forms white needles, and its aqueous, as 
-well as its alcoholic solution, has an acid reaction. When this 
solution is evaporated, or when the dry salt is heated to llO'', 
the neutral compound is obtained as a homy deliquescent mass. 
The neutral sulphate is very soluble in water, and crystallizes 
from hot alcohol in fine glistening tablets or scalea 

Ethyl hydrazine is only slowly attacked by oxidizing agents 
in acid solution, but it is quickly destroyed in alkaline liquids. 
It reduces Fehling's solution in the cold with evolution 
of nitrogen mixed with a combustible gaa The oxides of silver 
and mercury act in a similar way, the latter with formation of 
a small quantity of mercuric ethide. Ethyl hydrazine behaves 
like ammonia with respect to the salts of lead, nickel, cobalt 
and iron. The cobalt precipitate, however, is prevented from 
oxidation by the reducing action of the base, and hence it 
preserves its blue colour for a long time, whilst the precipitated 
ferric hydroxide is rapidly converted into the black hydroxide 
on warming. Heated with alcoholic potash and chloroform 
hydrazine gives the carbamine reaction (see p. 413), whilst with 
ethyl iodide it forms diethyl hydrazine and other ethylated bases. 

Potassium Ethyl Hydrazine Sulphonate, C2H5.NH.NH.SO3K, is 
formed by warming the base with potassium disulphate. It 
is very soluble in water, and separates out on addition of alcohol 
in fine glistening scales. When boiled with hydrochloric acid it 
decomposes into the base, and acid potassium sulphate, and 
when its concentrated solution is treated with mercuric oxide 
potassium diazoethane sulphonatc, CgHgNrrN.SOgK, is formed. 
This crystallizes in scales or needles which deflagrate strongly 
on heating when dry, and on treatment with zinc-dust and 
acetic acid is again converted into the original compound. 

264 Diethyl Hydrazine, (C2H5)2N2H2, is obtained by the 
action of zinc-dust and acetic acid on an aqueous solution of 
nitrosodiethylamine, when at the same time ammonia and 
diethylamine are produced : 

(C2HJ2N-NO + 2 H2 = (C2H,)2N-NH2 + H2O. 

(C2HJ2N-NO + 3 H2 = (C2HJ2NH + NH3 + H2O. 

In order to separate it from the diethylamine formed at the 
same time, it is converted into the difficultly soluble urea, which 
will be afterwards described, and which is decomposed by hydro- 
chloric acid into diethyl hydrazine, carbon dioxide, and ammonia. 
The base dried over caustic baryta is an easily mobile colourless 



412 THE ETHYL GROUP. 



liquid which possesses an ethereal and faint ammoniacal odour. 
It boils at 96'* to 99° and is easily soluble in water and alcohoL 
It is a monacid base, and forms soluble salts which as a rulo 
crystallize with difficulty. The platinichloride, (C2H5)^N^Hg 
PtClg, separates out in yellow needles on addition of platinic 
chloride to the alcoholic solution of the hydrochloride. Fehling's 
solution is reduced by the free base only on warming, with 
evolution of nitrogen and formation of diethylamine. This 
reaction may be employed to detect the presence of a nitros- 
amine in aqueous solution. It is heated slowly with zinc-dust 
and acetic acid to the boiling point, filtered and warmed with 
Fehling's solution after saturation with an alkali. The smallest 
quantity of the hydrazine which is formed may be detected by 
the precipitation of cuprous oxide. This reaction is only of course 
available when no other substances are present which either alone 
or by the action of nascent hydrogen act as reducing agents, 
such for example as the hydrazine bases, hydroxylamine, and 
the nitrogen acids, which latter yield bases. In such cases these 
bodies must be removed by distillation, either with an alkali or 
with an acid. 

265 Truthylazoninm Iodide, (C2HJ3N2H2I. This is formed 
by the union of diethyl hydrazine with ethyl iodide. It is easily 
soluble in water, and crystallizes from hot alcohol in white 
needles, which yield with silver oxide a strong alkaline 
hydroxide analogous to tetraethylammonium hydroxide, and 
this when heated with water yields diethyl hydrazine and 
ethylene. If its aqueous solution be treated with zinc-dust 
and -dilute sulphuric acid on a water-bath, triethylamine, hydri- 
odidic acid and ammonia are formed. This decomposition is a 
further proof that ammonium compounds contain pentad nitro- 
gen, for this reaction can only be explained under the supposition 
that the iodide possesses the following composition : 

N-OJL 

H.x/ \c:h, 

Tetracihf/l-Te(razon(\ (CjHJ^N^, is formed by the action of 
yellow mercuric oxide on a cold aqueous solution of diethyl 
hydrazine : 

2 (C.Hj)„N-NH4 + 4 1 1 «( ) = * " *^ l| + 2 Hg,0 + 2 H,0. 



CYANOGEN COMPOUNDS OF ETHYL. 413 



This compouDd is an almost colourless oil insoluble in water 
but soluble in alcohol, possessing a peculiar alliaceous smell. It 
does not solidify at — 20°. It volatilizes in aqueous vapour but 
cannot be distilled by itself, and when quickly heated partially 
decomposes with deflagration into diethylamine and nitrogen. 
It is easily soluble in acids, but its salts are very unstable. Thus 
the hydrochloric acid solution when heated to 70° — 80° decom- 
poses with a rapid evolution of nitrogen : 

This reaction is remarkable for the ease with which the ethyl 
group separates from the nitrogen and is converted into aldehyde, 
in order to yield the hydrogen necessary for the formation of the 
amine. 

The platinichloride, (C.2H5)8NgH2PtClQ, separates out from 
alcoholic solution in small golden yellow prisms. It dissolves in 
cold water without alteration, but like the chloride, decomposes 
on boiling. 

Tetraethyl-tetrazone acts as a strong base, decomposing many 
salts of the heavy metals. If a solution of this substance be 
brought in contact with silver nitrate, an almost instantaneous 
evolution of nitrogen takes place with formation of a silver 
mirror. Warmed with water and silver oxide the same phenom- 
enon takes place, silver acetate being at the same time formed. 
When shaken with a solution of iodine in potassium iodide a 
dark oil separates out which deflagrates when slightly warmed 
under water. 



CYANOGEN COMPOUNDS OF ETHYL. 

266 Ethyl Carhamine, CN.CgHg. If a mixture of ethylamine, 
chloroform, and alcohol be poured into a retort containing 
powdered caustic potash the liquid soon begins to boil violently 
and ethyl carbamine distils over together with ethylamine, 
chloroform, alcohol, and water, the first-mentioned substance 
being separated by repeated fractional distillation.^ It is, how- 
ever, obtained in the pure state more readily by acting with 
one molecule of ethyl iodide upon two molecules of silver 
cyanide in presence of some ether, the mixture being heated in 
sealed tubes for several hours to 130' — 140^- The crystallized 

^ Hofmann, Aim. Chem. Phnnn. cxlyi. 107. 

» Gautier, BuU, Soc. Chim. [2 J, viii. 216, 39r>, 400. 



414 THE ETHYL GROUP. 



compound CNAg + CNCjH^ is then formed, and this is distilled, 
after the evaporation of the ether, with half its weight of potas- 
sium cyanide and some water, the product being subsequently 
dried over calcium chloride and rectified.^ 

Ethyl carbamine is a colourless liquid having a repulsive 
penetrating odour. The inhalation of its vapour produces 
headache and giddiness. It possesses a slightly alkaline re- 
action, boils at 78** — 80**, and is converted into ethylamine 
formate when heated with water for twelve hours to 180^ 
Anhydrous hydrochloric or hydrobromic acid is absorbed ¥rith 
such avidity that a tarry mass is formed. In presence of ether 
the salts of ethyl carbamine are obtained, of which the hydro- 
chloride possesses the composition (CN.C2H5)2(C1H)3.* It forms 
white scales having a bitter taste. It is deliquescent and its 
solution quickly decomposes with formation of ethylamine and 
formic acid. If, however, it be treated with concentrated caustic 
potash in the cold, ethyl formamide is obtained as the chief 
product. This is also formed together with acetic anhydride 
when the carbamine is mixed with anhydrous acetic acid, con- 
siderable heat being evolved : 

Ethyl carbamine is also formed in small quantity by distilling 
the isomeric propionitril, a body to bo afterwards described, and 
it is converted mto this substance when heated in closed glass 
tubes to 180°. 

267 Ethyl Cyanate, NC.OCaH^ the normal cyanic ether, was 
obtained by Cloiiz' by acting with cyanogen chloride on a 
solution of sodium ethylate in a mixture of ether and alcohol. 
It was called by him cyanetlwlin in order to distinguish it from 
the isocyanate which was then supposed to be the tnie cyanic 
ether. 

It is a colourless oily liquid, possessing an ethereal smell and 
a sharp bitter taste, having a specific gravity of 1*1271 at 15°. 
Caustic potash decomposes it with formation of alcohol and 
potassium cyanurate. If hydrochloric or hydrobromic acid be 
passed into the solution, a thick mass is obtained which becomes 
solid within twenty-four hours, and on slightly warming yields 

* r.autier, Bull Soc, Chim, [2], ix. 211. 
• Bull. 8oc. Chim. (21, ii. 212. » Comjd. Rend. xliv. 42S. 



ETHYL CARBIMIDE. 416 

a distillate of ethyl chloride or bromide, cyanuric acid remaining 
behind.^ Ethyl cyanate decomposes easily into a crystalline 
mass which is a mixture of the two following compounds : ^ 

Diethyl amidocyanurate, C3N3(OC2H5)2NH2, crystallizing in 
slender white prisms, melting at 97^ 

Ethyl diamidocyanurate, 03N3(OC2H5)(NH2)2, a white crys- 
talline mass fusing above 190°. 

268 Ethyl Isocyanate, or Ethyl Carbimide, CO.NC2H5, was 
obtained by Wurtz' by distilling a mixture of one part of freshly 
prepared and well-dried potassium cyanato with two parts of 
potassium ethyl sulphate. The reaction begins at 180'', and is 
completed at 250^ The distillate is a mixture of ethyl iso* 
cyanate and isocyanurate, and these can be readily separated 
by distillation. Ethyl carbimide is a mobile liquid, boiling at 
60*, and having a specific gravity of 898. It possesses a 
suffocating, very irritating smell. It is converted by the action 
of water, ammonia, and the amines into the ethylated ureas. 

The following reaction takes place when it is heated with 
caustic potash : 

n|^^6 + 2HOK = CO(OK)2 + N-Jh ' 

It has already been stated that this was the reaction by which 
the amines were first obtained by Wurtz (see p. 401). 

Ethyl carbimide combines with anhydrous hydrochloric acid 
to form ethyl carhonyl ammonium chloride, N(C0)(C2H5)HC1, a 
liquid possessing a penetrating odour, boiling at 98**, and 
decomposed by water into ethylamine hydrochloride and carbon 
dioxide.* It forms similar compounds with hydrobromic 
acid.* 

Ethyl Isocyamcrate, C303(NC2H5)3, is easily formed from the 
foregoing compound, as also when potassium cyanurate and 
potassium ethyl sulphate are heated together to 200*. It 
crystallizes from boiling alcohol in rhombic prisms, which melt 
at So** and boil at 276° (Limpricht and Habich). When 
heated with ammonia it does not undergo change, whereas 
on treatment with potash, it decomposes with formation of 

* Gal, CompL Rend. Ixi. 527. 

' Hohnann and Olshausen, Ber. Deutsch, Chcm, Qes, iii. 269. 

* Ann, Chim, Phys. [3], xlii. 43. 

* Limpricht and Habich, Ann. Chem. Phami. cix. 107. 
» Gal, Bull, Soc. Chim. vi. 439. 



416 THE ETHYL GROUP. 



ethylamine and potassium carbonate. On the other hand, 
boiling baryta- water decomposes it into triethyUhiuret : 

CO— N.C2H5 CO— Nac^5 

C^H^.N CO + HoO = C2H5.N + CO, 

\ / \ 

CO— N.CaH^ CO— NH.C2H5. 

Ethyl isocyanurate is a thick oily liquid, which when heated 
yields diethyl-urea and ethyl carbimide.^ 

IHtthyl'isocyanuric Acid, C303N3(C2H5)2H, is contained in 
combination with ethylamine in the crude product obtained by 
distilling potassium cyanurate w^ith potassium ethyl sulphate, 
and is prepared from the mother-liquors of ethyl isocyanurate 
by boiling with baryta-water until ethylamine is evolved. 
Carbon dioxide is then passed through the liquid, and the 
filtrate evaporated, when triethyl-biuret first separates out 
and then the barium salt of diethyl -cyanuric acid ; this latter 
is then decomposed by sulphuric acid. The free acid crystal- 
lizes in hexagonal prisms or obtuse rhombohedrons. It melts 
at 173°, and volatilizes without decomposition. If silver 
nitrate be added to a hot ammoniacal solution, the salt, 
C303N3(C2H5)2Ag, separates out in needles (Limpricht Mid 
Habich). 

JUthyl Ferrocyanide, (C2HJ^(C^N3)^Fe2 + I2H2O. When an 
alcoholic solution of ferrocyanic acid is saturated with hydro- 
chloric acid, the compound (C2H5)g(C3N3)^Fe2 + 4C2H5CI + 
I2H2O is formed. This is deposited in colourless crystals which 
rapidly become blue on exposure to air. If these be dissolved 
in alcohol, and ether added, ethyl ferrocyanide separates 
out in pearly crystals which readily turn blue on exposure to 
air.^ 

Ethyl Platinocyayiide, (C2H5)2Pt(CN)^ + 2H2 O, is obtained 
by passing liydrochloric acid into a concentrated alcoholic solu- 
tion of platinocyanic acid (Vol. I., p. 417). It crystallizes in 
quadratic pink needles which easily decompose in the air with 
formation of alcohol. When heated on a water-bath they 
become lemon-yellow with fonnation of the anhydrous platino- 
cyanic acid : ^ 

(C.H^^PKCN), + 2 H2O = H,Pt(CN),+ 2C2H5.OH. 

* Limprirlit and Habieh, loc, eif. 

« H. L. Ruff, Ann. (.%'m, Pharm. xci. 2r»3. 

* V. Thann, Ann. t%m, Pharw, cvii. 315. 



ETHYL THIOCYANATE. 417 



Ethyl Cyanamidc, ^{C^^G^H, is formed by passing 
cyanogen chloride into an ethereal solution of ethylamine 
when a neutral syrupy liquid is obtained which, when dissolved 
in water and evaporated, and these operations frequently re- 
peatedy is converted into the polymeride, triethyl cyanuramide, 
NjHj(C2H5)3(CN)3. This has an alkaline reaction and 
crystallizes in needles. When heated with hydrochloric acid 
it is converted into triethyl isocyanurate. Both theso 
amides decompose when heated, solid ethyl dicyanamidc, 
(^C)^^^^^^, being left behind, and dieihylcyanamide, 
QiC)JS{C^^2f distilling over.^ This latter is also formed when 
ethyl iodide is heated with silver cyanamide (Vol. I., p. 67G). 
It is a liquid, boiling at 180", and decomposing when heated 
with strong hydrochloric ac^id as follows : - 

rex rH 

N \ an, + 2 H,0 = N \ C.H, + NH« + CO... 



( C0H3 ( c 



5 ^ "'''8 

2H. 



269 Ethyl Tliiocyanate, NC.SCoHg. Cahours ^ first obtained 
this compound by distilling a concentrated solution of potas- 
sium thiocyanate with potassium ethyl sulphate, and Lowig* 
prepared it by the action of ethyl chloride on potassium 
thiocyanate. It is also ea.sily fonned by heating ethyl iodide 
togetiher with many metallic thiocyanates, of which the mercury 
salt is however not one.^ In order to prepare it, an alcoholic 
solution of potassium thiocyanate is heated with ethyl iodide. 
The compound is separated out by the addition of water, and 
washed with a concentrated solution of common salt, as its 
specific gravity is very nearly e([ual to that of water. It is then 
dried over chloride of calcium.^ 

It is a mobile liquid possessing a penetrating alliaceous smell 
and sweet taste, boiling at 141*" — 2'' when the barometer is at 
733"*,^ and having at 0" a specific gravity of 1*033, and a 
vapour-density of 3018 (Caliours). P^tliyl thiocyanate is 
oxidized by nitric arid with formation of ethyl sulphonic 
acid, and on boiling with an alcoholic solution of potassium 



• Caboure and Clooz, Compt. liAnd. xxxviii. 354 ; Hofmann, Ber, Deutsch, Ch^m. 
0e3. ii. 600 ; iii. 264. 

• Fileti and Scliiff. Ber. Deuisch. Client, Oca. x. 427. 

» Ann, Chim. I'hys. [3], rv-iii. 264. *• Poriri, Ann. Ixvii. 101. 

• SchlagdenhaufTen, Ann. Chini. Phys. [3], Ivi. 207. 

• Baudrimont, Bull. Soc. CJiim. ' V. Meyer, Lichig's Ann clxxi. 47. 

VOL.. III. E E 



418 THE ETHYL GROUP. 



sulphide it is converted into potassium thiocyanate and mer- 
captan. Caustic potash converts it into potassium cyanide, 
potassium cyanate and ethyl disulphide.^ 
The latter reaction is represented as follows : 

2 NC.SCgH, + 2 KOH = j l^^gs + NCK + NCOK + H,0. 

V 2 6 

270 Ethyl Thiocarbimide, or Hthj/l Mustard Oil, CS.NCjHj. 
An alcoholic solution of ethylamine becomes waim on addition 
of sulphide of carbon, and fine six-sided tables separate out from 
the neutral solution consisting of ethylammonium ethylthiocar^ 

{NH C H 
^n/pVt ^H W^^^ acted upon by caustic soda it 

yields, with evolution of ethylamine, the sodium salt of ethyl 
thiocarbamic acid. This latter, on addition of hydrocl Joric acid, 
separates out hs a clear light oil, solidifying after some time to a 
saponaceous crystalline mass, whilst if a larger quantity of hydro- 
chloric acid be added it dissolves, carbon disulphide and ethyl- 
amine hydrochloride being formed. If the ethyl-ammonium salt 
above mentioned be heated under pressure to 110* — 120^ sul- 
phuretted hydrogen is evolved, and diethylthio-urea is formed 
(see p. 422), which, when heated with phosphorus pentoxide 
yields ethyl thiocarbimide : ^ 

This compound is more easily obtained by boiling the ethyl- 
ammonium salt of ethyl thiocarbamic acid and water with silver 
nitrate, mercuric chloride, or cupric chloride. The corresponding 
metallic salts of the thiocarbamic acid are first formed, and these 
decompose with production of a metallic sulphide, 8uphurette<l 
hydrogen, and ethyl mustard oil.^ Instead of the metallic salts 
an alcoholic iodine solution may be employed : 

^^ { SN^b^H^H + ^2 = CS.NC2H, + HI + S + N(C,HJH3l. 

As soon as the colour of the iodine has disappeared, the liquid 
is distilled and the thiocarbimide precipitated from the distillate 
by water.* 

* Briining, Jnn, Chem, Pharm. cir. 198. 
' Hofmann, Her. DriUsch, Ckem, Ots, i. 25. 
> Ber. Jkvtsch, Chcm. Ges, I 1C9. 
< 76. u. 452. 



ETHYLATED UREAS. 419 



Ethyl mustard-oil is also formed when ethylamine is heated 
with thiocarbonyl chloride, CSCIg.^ 

Ethyl thiocarbimide is a mobile liquid boiling at 134"^ and 
possessing a very irritating smell, and when dropped on the 
skin producing a burning sensation. The specific gravity of 
its vapour is 2*98. 

Heated with absolute alcohol to 110*' monothioeihylurethanc 
is formed : 

CS.NCoH, -f HO.C^H, = CSJ^^^^fi)^ 

This is a liquid possessing an alliaceous smell, boiling at 
204"* — 208**, and decomposed by dilute acids with formation of 
alcohol, ethylamine, carbon dioxide, and sulphuretted hydrogen. 
A compound isomeric with this is obtained when mercaptan 
is heated with ethyl isocyanate. It smells like the foregoing 
compound, boils at the same temperature, but is decomposed by 
dilute acids, as might be expected from its mode of formation, 
into mercaptan, carbon dioxide, and ethylamine. Its constitution 

is, therefore, CO | g^^^^^^^ 

When mercaptan is heated together with ethyl mustard oil a 
combination takes place, and a body is obtained resembling the 
foregoing. This cannot, however, be obtained in the pure state, 
as on distillation it decomposes into its constituents. This body 

is doubtless dUhioethylur ethane, CS \ o A A ^' 



ETHYLATED UREAS. 

271 Ethyl Carbamide, CO.N2H3(C2H5), is formed by the action 
of cyanic acid on ethylamine, and also by acting upon ammonia 

with ethyl carbimide : 

CO.NCoH, + NH3 = CO I ^§^2H5)H 

In order to prepare this body a solution of ethylamine sul- 
phate is boiled down to dryness with potassium cyanide, and 
the residue treated with alcohol. Ethyl urea crystallizes in 
striated monoclinic prisms, easily soluble in water and alcohol, 

* Rathke, Ann. Chem. Pharm. clxvii. 211. 

* Hofmann, Bcr, DciUsch. Cfum, Ges, ii. 116. 

E E 2 



420 THE ETHYL GROUP. 



melting at 92°, and decomposing at a higher temperature with 
formation of diethyl cyanuric acid (p. 416). When heated with 
caustic potash, potassium carbonate, ammonia, and cthylamine 
are formed.^ It absorbs hydrochloric acid gas with formation of 
the salt CO.N2H^(C2H^)Cl. The corresponding nitrate crystal- 
lizes in short thick prisms and, like the oxalate, it is slightly 
soluble in water. The hot aqueous solution of the urea 
dissolves freshly precipitated mercuric oxide, and on heating 
this solution, small needles separate out of the compound 

(.Q f N(C,H,)H 

"I NH ) 

r NH i ^o ' which is almost insoluble in cold water.* 

^^ { N(C,H,)H. 

a-Diethyl Carbamide, CO(NH.C2H5)2, is formed by the 
decomposition of ethyl isocyanato by water, as well as by the 
union of this substance with ethy lamine. 1 1 crystallizes from 
water in flat prisms, and from alcohol in silky needles. It melts 
at 112°o and boils at 2G3°. Heated with caustic potash it 
decomposes with formation of ethylamine, and combines with 
nitric acid to form a deliquescent nitrate (Wurtz). 

^'Diethyl Carbamide, CO < ;v/r?iT \ , is formed by the com- 
bination of die thy lamine and cyanic acid. The only reaction 
of this substance with which we are acquainted is that when 
heated with caustic potash it yields potassium carbonate, 
diethylamine, and ammonia. 

Tridhyl Carbamide, ^^ \ ^tn^ysx , is obtained by dropping 

ethyl isocyanate into diethylamine. It forms white crystals, is 
soluble in water, alcohol, and ether, mt^lts at 63°, and boils at 
223°. It decomposei with alkalis with formation of ethylamine 
and diethylamine.* 

Tetraethyl Carbamide, CO I ^in^\\^y 's not produced by the 

action of ethyl isocyanate upon triethylamine (Hofmann),* but is 
formed by passing carbonyl chloride mixed with double or 
treble its volume of jxitroleuin-spirit into dilute diethylamine. 
It is a pleasantly-smelling licjuid, boiling at 205°, dissolving in 
acids, and again separating out on the addition of alkalis.* 

* Wurtz, Compt.Rend, xxxii. i\A \ Rfp. Chim. Pure. iv. IflO. 

* Lpuckart, JoMm. Pmkt. Chrm. [2], xxi. 1. » Wurtz, lirp. Chim. Pure. iv. 199. 

* Hofiiiann, J'hil. Trans. 1851, ii. 370. 

* Michler, Ber, DniUch. Chrm, Oca. viii. 1664. 



ETHYL SEMICARBAZIDES. 421 



ETHYL SEMICARBAZIDES. 

272 The Dame azide has been given by Fischer to compourds 
formed by the replacement of the hydrogen in the hydrazine 
group by acid radicals. The corresponding ureas must, there- 
fore, be termed carbazides, and if these contain only one amido- 
group they are called semicarbazides.^ 

Ethyl Semicarhazide, or Ethylhydrazine Urea, CgHg.NH — 
NH.CO.NH2. In order to prepare this compound, an equivalent 
quantity of pure potassium cyanatc is heated to boiling with 
ethyl hydrazine hydrochloride in concentrated aqueous solution. 
On cooling, the urea, which is easily soluble in water, separates 
out on careful addition of solid caustic potash. The crystallized 
mass is dissolved in chloroform, the solution concentrated and 
ether added, when the compound is deposited in thin gUstening 
tablets melting at 105° — 10G°.^ 

a-Diethyl Semicarhazide, C.;PL^.^Qsn)^.CO.^{Pfi^)Yi. For 
the preparation of this compound, nitrosodiethyl-urea is employed. 
This latter body was discovered by v. Zotta,^ but its constitution 
was first recognised by E. Fischer."* It is obtained by passing an 
excess of nitrogen trioxide into an ethereal solution of diethyl- 
urea^ It is a yellow oil insoluble in water, from which solution 
transparent tablets separate at a low temperature. It possesses 
a burning taste and decomposes suddenly on heating. When 
brought in contact with phenol and sulphuric acid it colours the 
liquid first brown, then green, and finally a bright blue.^ By the 
action of acetic acid and zinc- dust it is converted into diethyl- 
hydrazine urea, an oily liquid which is easily soluble in water 
and alcohol, and can with difficulty be obtained crystallized. 
Its hydrochloride crystallizes in needles, and forms a difficultly 
Eoluble platinichloride. When this urea is boiled with con- 
centrated hydrochloric acid it at once decomposes into carbon 
dioxide, ethylamine, and ethylhydrazine (p. 410). 

^'Diethyl Semicarhazide, {C..fi^%'^ - KH. - CO.NHg. This 
urea forms the point of departure, as has already been stated, for 

* Ber. Deutsch. Ch^m. Ges, ix. 883. 

' Fischer and Troschke, Lichiys Ann. cxcix. 294. 

' Ann, Chem. Phann. clxxix. 101. * lb. cxcix. 283. 

• This reaction depends upon the liberation of nitrou-s a'^id. It was discovered 
by Liebcrmann {Ber. Deutsrh. Cfwrn. Gcs. vii. 247, 1008), an<l o(;curs in the case 
of almost all nitroso-compounds. 



NITRO-COMPOtJNDS OF ETHYL. 423 

diethyl carbamide (p. 420) is formed. If, however, ethylamine 
be present at the same time triethyl gvAxnidine is formed : 

Diethyltbiocarbamide. Ethylamine. 
Triethylguanidine. 

This latter compound is also formed by the action of sodium 
cthylate on ethyl isocyanurate/ and by heating chlorpicrin with 
ethylamine. It is very soluble in water. Its solution is 
caustic and alkaline, and it solidifies gradually on exposure to 
air by absorption of carbon dioxide. At a high temperature 
it distils, and partially decomposes with formation of ethylamine 
and a-diethyl carbamide. Hence it contains one molecule of 
water in very persistent combination, and, therefore, as it is a 
monacid base it is probably an ammonium hydroxide. 



NITROCOMPOUNDS OF ETHYL. 

• 

274 Nitroethane, CgHgNOg, was discovered by V. Meyer, and 
Stuber,* who obtained it by the action of ethyl iodide on silver 
nitrite, when together with this nitro-com pound about the same 
quantity of isomeric ethyl nitrite is produced. In order to 
prepare it on the large scale the foUowmg process may be 
adopted : 2090 grams of dry silver nitrite are brought into a 
large flask connected with a reversed condenser, and to this 
1700 grams of ethyl iodide are gradually added by means of 
a stoppered funnel, so that the liquid boils quickly but not too 
violently. As soon as all the ethyl iodide is added, the liquid 
is heated for some time on the water-bath, and then the 
condenser is turned round and the liquid distilled in the water- 
bath as long as any liquid comes over. It is next heated in 
an oil-bath, and the distillate collected separately. The residue 
in the flask, which consists of silver iodide and silver nitrite, 
is then finely powdered, and, on to this residue, the distillate 
which came over at 100° is poured, and the whole again digested 
in the manner described, when a further quantity of nitro- 
ethane is obtained. This is now added to the first portion, 

' Hofmann, Proc, Roy, Soc. xi. 281. 

' Brr. Deutsche Chem, Gcs. v. 399 ; Ann. Chtm. Pharm. clxxi, 1. 



424 THE ETHYL GROUP. 



and, in order to remove any ethyl iodide which may be present 
it is digested with an inverted condenser with 10 gnuns of silver 
nitrite, the whole being heated to boiling. The product is then 
purified by fractional distillation, when about 340 grams of 
nitroethane are obtained. 

Nitroe thane is a colourless strongly-refracting liquid having 
a pleasant peculiar ethereal smell. It boils at 113** — 114"* under 
a pressure of 737 mm. and has a specific gravity at 13* of 
1'0582, that of its vapour being 2-557. When ignited it bums 
with a pale flame. Its vapour cannot be heated above the 
boiling point without exploding. 

In contact with nascent hydrogen it is converted into 
ethylamine. This latter compound can be obtained in a 
perfectly pure state by digesting nitroethane in a flask with 
an excess of iron filings, and then adding acetic acid and a few 
drops of water, the whole being warmed until a reaction takes 
place, after which the flask is placed in cold water and the 
reaction is so regulated that the liquid does not boil. The 
liquid is then distilled with caustic potash, and a large yield of 
the base is thus obtained. If nitroethane be employed which 
contains a small quantity of ethyl nitrite, some ammonia is 
formed at the same time, and this can readily be removed by 
collecting the distillate in hydrochloric acid, evaporating over 
sulphuric acid, crystallizing, and treating with alcohol, when the 
insoluble sal-ammoniac remains behind. If nitroethane be 
heated with hydrochloric acid of specific gravity 1*14 it is con- 
verted into hydroxylaminc and acetic acid : 

{cS>o, + H«o = ^^(«H)H^ + {cabH. 

That nitroethane acts as a weak acid might bo expected from 
the fact that it contains the nitro-group (see p. 188). 

Sodium-nit roethanc, CoII^NaXOg, is obtained by acting on 
sodium with nitroethane diluted with benzene, or on nitroethane 
alone with alcoholic soda, when a white solid mass is obtained. 
This may be washed with absolute alcohol and dried on a 
water-bath. This compound is so slightly soluble in alcohol that 
very small quantities of nitroethane produce a precipitate with 
alcoholic solution of soda, whereby it may be readily detected. 
Alcoholic potash or ammonia however do not give any precipitate. 
Sodium nitroethane is a white light amorphous powder, which 
on heating in the open air burns off like gun-cotton, but when 
heated in a narrow test-tube detonates loudly. If kept 



NITROETHANE. 425 



for a length of time it becomes brown, and it deliquesces 
quickly on exposure to air. The aqueous solution gives a 
blood-red colour with ferric chloride, and a deep green colour 
with sulphate of copper. Silver nitrate gives a white pre- 
cipitate which soon becomes brown and afterwards black from 
separation of metallic silver. Mercurous nitrate gives a dirty 
green precipitate, whilst mercuric chloride added to the con- 
centrated solution of the sodium compound yields, after standing 
for a few moments, a crystalline mass consisting of a very stable 
compound having the composition ClHgCgH^NOg, the constitution 
of which is represented by one of the following formulae : 

It is soluble in water with difficulty, and acids separate nitro- 
e thane from its solution. 

275 MondbroinnitroetJiane, CgH^BrNOg. When nitroe thane is 
dissolved in an equivalent quantity of caustic soda or potash, and 
bromine added drop by drop, the colour of this substance dis- 
appears, and, on cooling with water, the addition of bromine may 
be continued until the liquid appears yellow, when a heavy oil 
separates out. This is a mixture of nitroethane, monobrom- 
nitroethane and dibromnitroethane, and from this the pure 
monobromnitroethane can be obtained only with difficulty. 
It is, however, easily prepared by adding little by little to the 
calculated quantity of bromine a solution of nitroethane in 
caustic potash.^ The explanation of the fact that when 
bromine is added in excess at the commencement of the opera- 
tion only the monobrom compound is formed, but that when 
it is added little by little the dibromnitroethane is produced, 
may be readily explained. The constitution of nitroethane and its ^ 
bromine substitution-products is given by the following formulae : 
CHjj CHg CH, 



i: 



CH2NO2 CHBrNOg CBrgNOo. 

and from these it is easy to understand why bromnitroethane 
is a stronger acid than nitroethane, whilst dibromnitroethane 
possesses no acid properties (p. 426). The following equation 
represents the change which occurs when bromine is added to 
potassium nitroethane : 

C,H,KNO, + Br^ = CgH.BrNOg + KBr. 

^ Tscherniak, Lifbig's Ann, clxxx. 126. 



426 THE ETHYL GROUP. 



The bromnitroethane, however, at once decomposes a corre- 
sponding quantity of the potassium salt, and nitroethane is 
liberated, upon which the bromine does not act, whilst the 
potassium compound of the bronmitroethane produced is acted 
upon by bromine.^ According to this explanation only nitro- 
ethane and dibromnitroethane should be formed. The occur- 
rence of the monobrom-compound is accounted for by the 
fact that the potassium nitroethane is more slowly attacked by 
the brom-compound than the potassium salt is by bromine 
itself. The decomposition takes place more slowly, and a 
certain excess of the monobrom-compound must be present, 
so that the quantity of the dibrom-compound obtained depends 
entirely upon the length of time during which the reaction 
proceeds. If this time be reduced to a minimum, a pro- 
duct is obtained which boils at 140** — 149°, from which the 
pure compound boiling at 146° — 147° may be easily obtained 
by fractional distillation. It is a very heavy oily liquid 
having an extremely penetrating smell, is easily soluble in 
alkalis, and yields a crystalline compound with caustic soda, 
whilst with alcoholic ammonia it unites to form a mass of 
glistening crystalline scales. These salts cannot, however, be 
obtained in the pure state, as they decompose easily with 
formation of a bromide. 

Dibromnitroethane, CgHjBrgNOj. In order to obtain this 
compound the requisite quantity of bromine is added to nitro- 
ethane, and a small quantity of water poured on to the top of 
the liquid, and to this mixture (which must be cooled down and 
shaken) dilute caustic potash is added until decolorization 
ensues. The dibromnitroethane which then separates out is 
removed, and bromine again added to the aqueous solution until 
it becomes yellow-coloured, when a further quantity of the 
dibrom-compound is obtained. The raw product is decolorized 
by shaking with caustic potash and adding it to that obtained, 
mixed witb "water, dried over chloride of calcium and distilled.^ 

Tlfis substance is a colourless mobile liquid, having a very 
penetrating odour, and boiling at 165°. 

376 Dinitroethane, C2H^(N02)2. To prepare this com- 
pound, bromnitroethane is dissolved in twice its volume of 
alcohol, and the liquid shaken up with a solution of potassium 
nitrite dissolved in its own weight of water. Alcoholic caustic 

1 Meyer and Tschcrniak, Li^iga Ann. rlxxx. 114. 



Meyer anc 
V. Meyer, 



Lifbig'n Ann, clxxv. 128. 



DINITROETHANE. 427 



potash is then added, the liquid being cooled, and a mixture of 
potassium bromide and the potassium salt of dinitroethane 
separates out, as is seen by the following equation : 

CH3 + KOH + KNO2 = CH3 + KBr + H^O. 
CHBrNOo C] 



'2 



IKCNO^), 



The crystalline mass is washed out with ether, and then the 
dinitroethane separated by means of dilute sulphuric acid. 

It is a colourless strongly-refracting liquid, having a faint 
alcohol-like smell, and a peculiar sweetish taste, boiling at 
185**— 186^ and having a specific gravity of 1-3503 at 2S''5. 
It is somewhat soluble in water, and is a tolerably strong acid 
which decomposes carbonates, although not very easily. It is 
converted into hydroxylamine, ammonia and acetic acid, by 
the addition of tin and hydrochloric acid, and the product also 
contains some aldehyde. This decomposition is represented by 
the following equations : 

CH3 CH3 



i 



+ 4>B^= I + 2 N(OH)Hj + HjjO. 
H(NOjj)j CHO 



CH3 CH3 



d 



+ N(0H)H2= I +NH8. 

HO CO.OH 



Dinitroethane forms well crystallized salts. The potassium 
compound, C2H3K(N02)2, is obtained by adding alcoholic potash 
to a solution of dinitroethane in alcohol. It forms pure 
yellow, brightly glistening crystals, which become opaque and 
red on exposure to air, but regain their colourless appearance 
when again placed in the dark. On quickly cooling the hot 
aqueous solution, the compound separates out in the form of 
tiibles or long needles, and by evaporation, or by slow cooUng, 
it is obtained in fine monoclinic prisms. It explodes very 
violently by a slight blow, or even at the touch of a warm 
object, with formation of red vapours. 

The yellow salts which dinitroethane forms with sodium, 
ammonium, barium and calcium, are also soluble in water and 
crystallize well. The silver salt, C5jH3Ag(N02)2, is a fine 
yellow crystalline precipitate, which is deposited from warm 



428 THE ETHYL GROUP. 



solution in bright metallic-glistening scales, and is as explosive 
as the potassium compound.^ 

Bromdinitroetliane, C2H3Br(X02)2, is formed when an 
aqueous solution of potassium dinitroethane is shaken with 
the calculated quantity of bromine water. It is a colourless 
heavy oil having an extremely pungent smell. It is volatile 
in presence of aqueous vapour, but when it is heated alone it 
decomposes suddenly with formation of bromine vapours. It 
is decomposed by caustic potash as follows (ter Meer) : 

C2H3Br(N02)2 + 2 KOH = C2H3K(NO,)2 + KBr -h H^O + O. 

277 Ethyl Nitrolic Acid, C2H3(N02)NOH. This compound, 
discovered by Victor Meyer,^ is easily formed when an alkaline 
solution of nitroethane is mixed with potassium nitrite and 
then acidified with dilute sulphuric acid : 

CH.3 CH3 

CH2 4- ON.OH = CN.OH + H^O. 



NO2 NO2 

It also occurs when an aqueous solution of hydroxylamine is 
well shaken with dibromnitroethane dissolved in alcohol for 
the purpose of fine division : 

I I 

0Br2 + N(0H)H2 « CNOH + 2HBr. 

In order to prepare it, nitroethane is dissolved in the requi- 
site quantity of weak caustic soda, an excess of potassium 
nitrite added, and the whole acidified, so that nitrous fumes 
are evolved. Alkali is then added in excess, the reddish - 
brown solution again acidified, and this process repeated three 
or four times.* The liquid is then shaken up several times 
with ether, which dissolves the nitrolic acid, and this separates 
out in crystals on evaporating the ethereal solution. A single 
crystallization from water suffices to yield it chemically pure. 
It crystallizes in splendid pale-yellow transparent rhombic prisms 

* ter Meer, Lubig'n Ann. rlxxxi. 1. * LUbig'n Ann. clxxr. 88. 

• ter Meer, LUbig*i Ann, clxxxi. 1. 



ETHYL NITROLIC ACID. 429 



having a bright lustre and a slight bluish fluorescence and re- 
sembling in general appearance crystals of saltpetre. This body 
has an intensely sweet taste. It is so much more soluble in hot 
than in cold water that if a solution be saturated by the warmth 
of the hand, crystals at once form when the hand is removed. 
Nitrolic acid dissolves in solutions of the alkalis and alkaline 
earths with an intense red colour. The salts which are thus 
formed are, however, extremely readily decomposed, and have 
not been obtained in the pure state. Their solutions yield, 
with various metallic salts, coloured precipitates, which are also 
very unstable. Nitrolic acid gradually decomposes on keeping, 
leaving acetic acid containing the oxides of nitrogen, and when 
heated it begins to melt at 81° and decomposes quickly, often 
with explosive violence, according to the equation : 

2 C2H4N2O3 = 2 CoH.Og + NOo + N 

If it be heated with water, or better with dilute sulphuric acid, 
nitrogen monoxide is obtained, together with aoetic acid, and the 
same reaction takes place with concentrated sulphuric acid in 
the cold. In this way two successive reactions take place. At 
first acetic acid, hydroxylamine, and nitrous acid are formed : 

CHj CHq 



h 



=NOH + 2 H,0 = C=0 + N(OH)H. + NO.H, 

I I 

NOj OH 

and the latter two compounds mutually decompose as follows : 

NOH3 + NO,H - 2H2O + NjO. 

Sodium amalgam and water also give rise to acetic acid and 
nitrous acid, together with ammonia formed by the reduction 
of the hydroxylamine. It is clear that hydroxylamine is pro- 
duced in this decomposition, because if zinc and dilute hydro- 
chloric acid be employed for the reduction, only acetic acid 
and hydroxylamine are obtained : ^ 

CH3 CH3 

I I 

C=N.OH + H.,0 + 2 IL = 0=0 + 2 H»N.OH. 

I • 

NOj OH 

* Meyer and Locher, Lichig a Ann. clxxx. 170. 



432 THE ETHYL GROUP. 



The separation and purification of the phosphlnes is accom- 
plished without any difficulty, these bodies thus exhibiting a 
marked difference from the amine bases, the separation of which 
is difficult and tedious. In the first place it must be borne in 
mind that under the above conditions a tertiary base is not formed. 
In order to separate the ethyl phosphine, the contents of the tube 
are brought into an apparatus filled with hydrogen (Fig. 62)» 
into which a slow current of water, free from air, is allowed to 
enter. This decomposes the salt of the primary base, correspond- 
ing to the iodide of phosphonium, into ethyl phosphine and 
hydriodic acid. The first of these is condensed by passing 
through a spiral tube surrounded by ice and dried over caustic 
pota.sh. As the current of hydrogen carries away a con- 
siderable quantity of the very volatile ethyl phosphine, the 
gas is passed through a concentrated solution of hydriodic 
acid. At last the whole is warmed, and when no further 
evolution of ethyl phosphine takes place, a strong solution 
of caustic soda is allowed to run into the retort, when so 
much heat is evolved that diethyl phosphine volatilizes; and 
this is then condensed by an ordinary cooling apparatus in 
an atmosphere of hydrogen, and also dried over caustic potash. 

Ethyl phosphine is a very mobile colourless liquid, in- 
soluble in water, and possessing a strong refractive power. 
It boils at 25^, and does not act on vegetable colouring matters. 
Its smell is most overpowering, closely resembling that of the 
carbamincs, and its vapour, like that of the latter bodies, 
produces an intense bitter taste on the tongue and in the 
throat. The vapours bleach cork like chlorine, and caoutchouc 
brought in conUict with them is rendered translucent and loses 
its elasticity. Ethyl phosphine ignites in contact with 
chlorine, bromine, and fuming nitric acid, and yields with 
sulphur and carbon disulphide volatile compounds. 

Ethyl phosphine is a weak base, which unites with concen- 
trated \vdracids and the elements of tlie chlorine group to form 
salts which are quickly docomi)osud by water. The hydrochloride 
forms a i)latinichloride which crystallizes in fine crimson-red 
needles. Ethyl phosphonium iodide is a splendid salt, crystal- 
lizing in shining white four-sided tables slightly soluble in con- 
centrated hydriodic acid. On the addition of ether it separates 
out in large woll-forniod tables, which are so thin that they 
exhibit iridescence. Heated in an atmosphere of hydrogen they 
sublime at 100"*, forming a mass resembling sal-ammouiac. 



TRIETHYL PHOSPHINE. 433 

280 Ethyl Phosphmic Add, P(C2H5)03H2. This substance is 
obtained by the action of fuming nitric acid on ethyl phos- 
phine, and may be regarded as orthophosphoric acid in which 
hydroxyl is replaced by ethyl. It is separated from the 
phosphoric acid, which is* formed at the same time, by boiling 
the solution with oxide of lead, and treating the mixture 
of the lead salts with acetic acid, which leaves the lead phos- 
phate insoluble. Sulphuretted hydrogen is then passed through 
the solution, and the filtrate evaporated on a water-bath. The 
residual oily liquid solidifies on cooling to a spermaceti-like 
mass, which melts at 41° and can easily be distilled. Although 
it is very soluble in water, it is only with difficulty moistened 
by this substance. It is dibasic ; the silver salt, P(C2H5)03Ag2, 
is an insoluble yellow powder.^ 

Diethyl Phosphine, P(C2H5)2H, 

is a colourless liquid, lighter than wat^r and having a high 
refiractive power. It boils at 85®, and possesses an extremely 
penetrating smell, but one quite diff'erent from ethyl phos- 
phine. It absorbs oxygen with great avidity, becoming thereby 
so hot that inflammation may ensue. It dissolves very easily in 
acids. Its salts, which are not decomposed by water, crystallize 
only with difficulty, with the exception of the hydriodide and 
the platinichloride, the latter forming fine large orange-yellow 
prisms, "which however are very unstable. 

Diethyl phosphine combines with sulphur and carbon di- 
sulphide to form liquid compounds. Nitric acid oxidizes the 
base to diethyl phosphinic acul, 'P{C^^fi^, a liquid which 
does not solidify at — 25^ and yields a silver salt, P(C2H5)202Ag, 
which is precipitated from its aqueous solution in fine silky 
needles. 

Triethvl Phosphine, P(C2H5)3. 

281 This was first prepared by Cahoursand Hofmann,^ by the 
action of zinc ethyl on phosphorus trichloride, in a similar w^ay 
as the corresponding methyl compound (see p. 232). Hofmann 
afterwards found that it is better to decompose the double 
compound of triethyl phosphine and zinc chloride, formed by 
the continued action of concentrated caustic potash, and to 
distil the base from this mixture.^ This compound is also 

' Hofmann, Brr. DciUsch. Chcm. Ges. v. 110 ; Chfm. Soc. Jmim. xxv. 422. 
« Chan. Hoc, Joimi. xi. 01. ' Phil. Trans. 1860, 410, 

VOL. III. F F 



430 THE ETHYL GROUP. 



278 Dinitroethylic Acid} (C2H5)N202H. Nitric oxide is very 
slowly absorbed by zinc ethyl. The reaction may, however, be 
accelerated by working underpressure. The first product of this 

reaction is ethyl zinc dinitroethylate, NgOg-j y^p^xr which 

may be obtained when an ethereal solution is employed, in 
large colourless transparent rhombohedral crystals which oxidize 
in the air, and are decomposed by water with evolution of gas, 
as follows : 

2N A { Z^C^H/ ^^^ " ^^*^ "^ NjO,(C,H02 Zrx + Zn(OH)^ 

Zinc hydroxide is, however, not precipitated, but a basic salt is 
formed which yields an opalescent solution having a strong 
alkaline reaction and a peculiar bitter taste. When car- 
bon dioxide is passed into the liquid the normal zinc salt, 
2N^O^(C2H5)2Zn.+ H2O, is formed, crystallizing in thick 
rhombic prisms (Zuckschwerdt). If this be decomposed with 
dilute sulphuric acid, and the liquid distilled under diminished 
pressure, a solution of the free acid is obtained, possessing 
an acid reaction and a pungent taste. It is an extremely 
unstable compound, decomposing even at the ordinary tem- 
perature with evolution of nitrogen, of the monoxide and 
dioxide of nitrogen, and of ethylene. 

The sodium salt is easily prepared by passing nitric oxide into 
sodium zinc ethyl, Na Zn (02115)3.2 

A series of other salts have been prepared from the zinc salt, 
of which those of the alkalis and alkaline earths deflagrate like 
guiipowder ^en heated below a red-heat, and the zinc salt 
when quickly warmed to 300* bums with a fine bluish-green 
flame. The copper salt, 2N^O^(C2H5)2Cu + HoO, crystallizes 
from a fine purple-coloured solution in long needle-shaped four- 
sidfid prisms of the same colour. Nascent hydrogen converts 
dinitroethylic acid into ammonia and ethylamine : ' 

N202(C.,H,)H + 4 H2 = NH3 + C2H5.NH2 + 2 H2O. 
From this it appears that the acid contains one atom of 



1 Frankland, Phil. Trans. 1857, p. 68. 

* Frankland and C. C. Graham. Joum. Chem. Sor. 1880, I. 578. 

• Zuokschwerdt, ytnn. Chem. Pharm. clxxiv. 302. 



ETHYL PHOSPniXE. 431 



nitrogen in direct combination with ethyl, and that the foUow- 
ing formula represents its constitution : 

C,H,— N— X— OH. 

O 

Diazodhoxane, (C^^^Jd^, is produced by the action of ethyl 
iodide on silver hyponitritc (Vol. I. par. 2:17) ; it is a light, colour- 
less liquid, possessing a peculiar ethereal odour. Although it is 
almost as explosive as nitrogen chloride, it was found jx^ssible 
to determine its vapour density, which is 41. Hydrogen in the 
nascent state converts it into alcohol and nitrogen gas. Hence 
its constitution is most probably expressed by the formula : 

CjHg -0-N = N-0- C0H5.1 

PHOSPHORUS BASES OF ETHYL. 

279 Ethyl Phofiphim, P(C2H0H2. This compound, discovered 
by Hofmann,* is obtained by a method analogous to that employed 
for the preparation of the corresponding methyl compounds 
(p. 229). A mixture of five grams of zinc oxide, twenty grams 
of phosphonium iodide, and twenty grams of ethyl iodide, is 
heated in a closed glass tube of about 50 cbc. capacity for from 
six to eight hours to 150^ It is best first to bring the phos- 
phonium iodide into the tube, then the oxide of zinc, and lastly 
the iodide of ethyl. Mixed in this way the bodies do not attack 
one another in the cold ; and the tube may be easily sealed up. 
On opening the tube, after tlie operation is o^er, a disengage- 
ment of gas takes place, as various gaseous bodies are formed 
in the reaction, amongst which ethane is probably contained, 
and also frequently phosphuretted hydrogen. Tlie chief product 
of this reaction is ethyl phosphonium hydriodide, which forms a 
double salt with the zinc iodide also formed : 

2C.^HJ + 2PH,I + ZnO = 2 PCCUyHjI + Znl, + HoO. 

This reaction is accompanied by another one, in which diethyl 
phosphine is produced, this body combining directly with zinc 
iodide : 

2 CoHJ + PH4I -f ZnO = P( C,H,),H J, Znl, -h H,0. 

* Zom, Ber. Dcvtach. Chrm. (7at. xi. IfiSO. 

■ lier. Deuisch, Chcm. Ors. iv. 430 ; Ch-m^ Sor. Joum, xxiv. 713. 



TUIETUYLPHOSPHINE COMPOUNDS. 437 

insoluble in ether. If an aqueous solution of the hydro^ 
chloride be mixed with a slight excess of platinic chloride, and 
heated to boiling, the red precipil^ate which at first forms 
disappears, and light yellow crystals separate out from the con- 
centrated solution, having the composition Pt[P(C2H5)3]^PtCl4, 
and therefore analogous to Magnuses green salt (Vol. II. part ii. 
p. 411). This compound is readily soluble in ether, and crys- 
tallizes from ethereal solution in large amber-yellow transparent 
mouocliuic prisms, which melt at 150^ and may be heated to 
250'' without decomposition. Together with this compound 
an isomeric body is formed, crystallizing in small white prisms. 
K the yellow compound be heated with triethylphosphine and 
water, colourless crystals having the composition [PCCgHj) J^PtCIj 
are formed, which are easily converted with separation of tri- 
ethylphosphine into the white compound already mentioned, and 
give with silver oxide and water a strongly alkaline solution, 
from which other salts corresponding to the plato-diammonium 
compounds can be prepared.^ 

283 TrUthylplwsphine Sulphide, P(C2H5)3S. If a piece of sul- 
phur be thrown into a test-tube containing triethylphosphine it 
melts with evolution of heat, running about on the top of the 
liquid until at last it disappears. On cooUng, the liquid solidifies 
to a splendidly crystalline mass. This experiment requires care, 
inasmuch as the vapour of the base when brought in contact 
with air forms an explosive mixture. In order to prepare the 
sulphide in larger quantity, flowers of sulphur are heated in a 
dilute ethereal solution of the base as long as they dissolve. 
Thfe ether is then evaporated off and the residue crystallized 
from boiling water. On cooling, it separates out in long glisten- 
ing needles or hexagonal prisms, which melt at 94°, and are 
volatile in a current of steam. When heated with sodium, tri- 
ethylphosphine is produced, whilst nitric acid converts this 
compound into the oxide. 

Triethylphosphine Selenide, P(C2H5)3Se. Selenium combines 
directly with this base, but with less energy than sulphur. 
The compound crystallizes from aqueous solution with the same 
ease with which the sulphide does, and is decomposed in contact 
with the air. 

Triethylpliosphine Carbonyl Sulphide, T^C^^^fiS^^ This mag- 
nificent and characteristic compound is formed by the direct 
union of the base with carbon disulphide, the combination 

» Cahours and fJal. /?»/// *SV. rhim. [2], Niv. 3S6. 



438 THE ETUYL GROUP. 



taking place so energetically that an explosion may occur. It 
is, therefore, better to prepare the compound in an alcoholic or 
ethereal solution. It is insoluble in water, difficultly soluble in 
ether, but easily dissolves in hot alcohol, from which, on cooling, 
it is deix)sited in red needles resembling chromium trioxide^ 
whilst by the spontaneous evaporation of the ethereal solu- 
tion large deep-red monoclinic crystals are obtained exhibiting 
dichroism, melting at 95* and evaporating at 100^ The com- 
pound is soluble in strong hydrochloric acid, and this solution 
yields, with platinic chloride, a yellow amorphous compound, 
[P(C2H^)3H]2PtClo, which is insoluble in alcohol, and very 
easily decomposed. When an alcoholic solution is boiled with 
silver oxide or silver nitrate the following reaction takes place : 

PraH5)3CS, + 2 AgoO = AgjS + Ag, + C0« + P(C,HO,S. 

Moist air gradually produces a similar change. If, however, it 
is heated with water to 100** the following reaction occurs : 

4 P(aH,)3CS, + 2 HP = 2 P(aH,)3S + P(aH,)30 + 

P(aH,)3(CH3)OH + 3CSo. 

The methyl triethyl phosphonium hydroxide thus formed yields 
a platinichloride crystallizing in splendid octohedrons. 

The formation of the red compound takes place so easily and 
sa quickly that it may be used as a means of detecting the 
smallest trace cither of carbon disulphide or of triethyl phos- 
phine.* If it is desired to test for the latter body, the liquid is 
poured on to a watch-glass, and the vapour of carbon disul- 
phide allowed to How on to it from a bottle containing this 
liquid, when the glass becomes covered with a network of red 
crystals. By help of the triethylphosphine the presence of 
exceedhigly small tmces of sulphide of carbon may be detected, 
as, for example, in the most carefully purified coal-gas.* 

The constitution of this peculiar compound is probably as 
follows : 

I p-c;h 
s=c/ \aa 



'2 "-5 



^\^len heated with a saturated solution of sulphuretted hydro- 
gen to 100" it decomposes into carbon disulphide, trietliyl- 
phosphine sulphide, and yellow crystals having the formula 

• Tho otliLT UTtiiiry )»1iob{)hiiirb form Himilur coiuimiuikLs. 
' ^r»flnuul^ Phil. Trans, lS6o, |i. VH. 



TETRAETHYLPHOSPHONTUM COMPOUNDS. 439 

CgHjgPS^ insoluble in ether, and probably having the constitu- 

tion CS -J GT>/ri^Tj N XT If these be heated with water, carbon 

disulphide is separat id, and an alkaline solution is formed which 
yields with acids well-defined salts. The difficultly soluble 
iodide crystallizes in long needles, having the composition 
P(SCH3)(C2H,)3U 

Tetraethylphosphonium Compounds. 

284 Wlien trietliylphospliine is mixed ^vith ethyl iodide a 
violent reaction takes place in a few moments. The liquid froths 
up, and solidifies on cooling to a white crystalline mass of 
tetraethylphosphonium iodide. Tliis compound is also formed 
together with triethylphosphine, when absolute alcohol acts on 
phosphonium iodide (Vol. I. p. 477) : 

4C2H5.OH + PH,I = P(C2H5),I + 4H2O. 

It is exceedingly soluble in water, less so in alcohol, and 
insoluble in ether. If ether bo added to an alcoholic solution 
until the white crystalline powder which begins to separate 
dissolves on boiling, finely formed crystals are deposited on 
cooling. If silver oxide bo added to its solution, silver iodide 
is quickly formed, and a strongly alkaline liquid which retains 
some silver oxide in solution. If this be allowed to dry over 
sulphuric acid, metallic silver separates out in the form of a black 
powder or in that of a mirror, and a crystalline mass of the 
hydroxide is obtained, which is odourless, and possesses a bitter 
taste somewhat resembling that of phosphonis itself. Its solu- 
tion exhibits most of the reactions of caustic potash, except 
that it does not easily dissolve the oxides of zinc and alumi- 
nium. On dry distillation it is decomposed into triethylphos- 
phine oxide and ethane. The chloride, sulphate, and nitrate 
prepared from this are crystalline, but extremely deliquescent 
bodies. The platinichloride is an orange-yellow precipitate, 
which is difficultly soluble in boiling water. The aurichloride 
crystallizes from hot water in glistening golden needles. 

Tricthylmcthylphosplionium Iodide, P(C2H5)3(CH3)I. If methyl 
iodide bo brought together with triethylphosphine, it unites 
with it vdi\i such force that an explosion may occur, and hence 
it is necessary to dilute with other. The compound resembles 

* Hofraanii, Vroc, Rcty. Soc. xi. 283. 



440 IHE ETHYL GROUP. 



that of tetraethylphosphonium, and, like this, yields a stroDgly 
alkaline hydroxide and a platinichloride which has already been 
mentioned. 



ARSENIC COMPOUNDS OF ETHYL. 

285 These bodies exhibit close analogy with the corresponding 
methyl compounds. But, with the exception of the triethyl- 
arsino, they have not been so carefully examined as the latter 
series. 

Triethylarsine, Aa(C2ii^^ occurs together with arsendi- 
methyl, As2(G2H5)4, as the principal product of the action of 
ethyl iodide on sodium arsenide : 

AsNag + 3 CsjHgl = AslC^Hg), + 3 Nal. 

The product is subjected to distillation, and the distillate 
rectified in an atmosphere of carbon dioxide.^ Triethylarsine 
is also formed by the action of zinc ethyl on arsenic trichloride.* 
It is a highly refracting mobile liquid possessing a disagreeable 
smell, boiling at 140** and having a specific gravity of 1*151 
at 16°7, whilst that of its vapour is 5**-278 (Landolt). It 
fumes in the air and takes fire when slightly warmed. When 
the air is allowed to act slowly upon it, tabular crystals 
having an acid reaction are formed. The composition of these 
has however not been determined. Triethylarsine is decomposed 
by concentrated nitric acid with evolution of light and heat, 
but an acid of specific gravity 1*42 converts it into triethyl- 
arsine nitrate, which forms deliquescent crystals. 

Triethylarsine Qjtiiky A&((^^^fi, is formed, together with 
other bodies, when an ethereal solution of triethylarsine is 
allowed to evaporate in the air, as well as when the correspond- 
ing iodide is heated with caustic potash. It is a liquid 
insoluble in water, which may be distilled without decomposi- 
tion, and possesses an irritathig smelL When warmed with 
concentrated hydnx'bloric acid it evolves a most unbearable 
odour, ])robably due to the formation of a chloride which 
however has not yet been isolated. 

Triethylarsine Dromide, ^iS^^^^v^y is produced when an 
alcoholic solution of its constituents is allowed to evaporate. 

' biuilolt, Ann, Chtm. Phann, Ixxxix. 801 ^ xcii. 361. 
2 Cnhours an<l llormrinn, Compt, liend. xli. 831. 



ARSENIC COMPOUNDS OF ETHYL. 441 

It forms yellow crystals which have a bitter taste and excite 
saeezing. 

Triethylarsiru Iodide, As(C2H5)3lj, is obtained as a yellow 
precipitate by adding iodine to an ethereal solution of triethyl- 
arsine. By the action of platinic chloride on triethylarsine 
the salt Pt[As(C2H5)3l^PtCl^ is produced which is isomor- 
phous with the corresponding phosphine compound (p. 437). 
An isomeride is also formed at the same time in long 
light yellow prisms. Both bodies are converted into the salt 
[As(C2H5)3]^PtCl2 by the further action of the arsenic base 
(^Cahours and Gal.) 

Tridhylarsiiie Suljyhide, As(C2H5)3S, is produced when an 
ethereal solution of triethylarsine is warmed with flowers of 
sulphur. It crystallizes in fine prisms soluble in hot water and 
melting a little above 100°. It has a bitter taste. Hydro- 
chloric acid decomposes it with evolution of sulphuretted 
hydrogen, and its solution precipitates black sulphide of silver 
from silver salts, but it has no action on those of copper 
and lead. 

Tbtraethylarsonium Compounds. 

a86 The iodide, As(CoH,j)^I, is readily produced by gently heat- 
ing ethyl iodide with triethyl arsine. It is easily soluble in 
water and alcohol, and crystallizes in long colourless needles 
which turn brown on exposure to air. When distilled 
with caustic potash it decomposes into the bodies from which 
it is formed. It unites with iodine to form the periodide, 
As(C2H5)^l3, a body which in appearance resembks potassium 
permanganate. A compound with arsenic tri-iodide, As(C2H5)^I 
+ Aslj, may be obtained by heating arsenic with ethyl iodide 
to 180° ; it forms red tables and crystallizes from alcohol 
in needles, and is decomposed by caustic potash with forma- 
tion of tetraethylarsonium iodide, and distilled with this body 
ir. yields pure triethylarsine. 

If an alloy of arsenic and zinc be heated with ethyl iodide 
to 175°— 180^ the compound 2As(C2H5)J + ZnIg is ob- 
tained crystallizing from alcohol in fine prisms. A correspond- 
ing cadmium compound has also been prepared. Both bodies 
are decomposed by caustic potash in a similar way to the 
arsenic iodide compound. ^ 

' Caboure, Compt, Eend. xiix. 87 ; 1. 1022. Ann. Chem. Pharm, cxii. 228; 
cxvi. 364. 



442 THE ETHYL GROUP. 



Tctraethylarsonium Hydroxide, As(C2H5)^OH, is obtained by 
acting with silver oxide on an aqueous solution of the iodide. 
A strongly alkaline caustic liquid is left behind, which on 
evaporation in a vacuum yields the hydroxide as a deliquescent 
crystalline mass, and this when saturated with hydrochloric 
a(id gives the chloride, As(C2H5)^Cl + 4H2O, a crystalline 
substance soluble in water and alcohol and uniting with 
mercuric chloride and platinic chloride to form crystalline 
compounds. 

Various other tetraethylarsonium salts are known. More- 
over diviethylethylarsine, diethylmcthylarsine, and their com- 
pounds and derivatives have been prepared.^ 

Diethylarsinc or Ethyl Cdcadyt, As^{Cfi^^. In order to 
prepare this body, a mixture of one part of sodium arsenide and 
five parts of quartz sand is placed in a number of small flasks 
and each moistened with ethyl iodide. As soon as the energetic 
reaction is over, the mass is heated in connection with a 
reversed condenser and ethyl iodide again added until all the 
triethylarsine is converted into the arsonium iodide. Tho 
product is then extracted with ether in an atmosphere of 
carbon dioxide, the Eolution mixed with absolute alcohol and 
the ether distilled off. On addition (f water free from air 
to the residue, diethylarsine separates out, and this is dried and 
rectified in a current of carbon dioxide. The same compound 
is also formed when diethylarsine iodide, As((u^}i^J,, is distilled 
with zinc amalgam.* 

Diethylarsine is a heavy highly refracting liquid having an 
unbearable alliaceous (dour and boiling at 185** — 190°, and 
oxidizing quickly in the air without however taking fire. In 
this cat:e diethyluisine oxide, a substance which has not yet 
been fully examined, is produced. It unites a'so with the 
elements of the chlorine group and with sulphur, forming 
fconqx)untl3 which closely resemble the corresponding methyl 
compounds but have not been further examined. 

aUiyl Cacoilylic Acid, AfiO(C2H^20H, is formed by the 
action of air on the foregoing compound in the presence of 
water, or, more rapidly when diethylarsine is shaken up with 
water and mercuric oxide, when a readily soluble and crystalline 
mercuric salt is formed. This is decomposed by baryta-water, 

* CttliourM, Amu Chtm, PKarm. c\\\\. 192, 329 ; Ann. Cliim. Phya. [3], Ixii. 
291. 
^ Cuhuurd and RicLc, Commit. R* nd. xxxvL 1001 ; xxxix. 541. 



ANTIMONY COMPOUNDS OF ETHYL. 443 



the liquid treated with carbon dioxide, and afterwards the 
barium exactly precipitated with sulphuric acid. On evapora- 
ting this solution, the free acid is obtained in glittering scales 
or tables which have an acid reaction and a bitter taste. They 
melt at lOO"" and are not attacked by concentrated nitric acid or 
even by aqua-regia (Landolt). The same compound is also 
formed when diethylarsine iodide is treated with silver oxide 
and water : 
2 AsCCgHj),! +3 AgaO+HgO = 2 AsO{CJI,)j011 + 2 Agl + 4 Ag. 

Mondhylarsine Compounds are but little known. The iodide 
is formed by the action of iodine on diethylarsine iodide : 

As(C,H,),I + I, = As(C,H,)I, 4- C,H,I. 

It may also be prepared in a similar way from diethylarsine. 
Its properties have not been fully examined. When treated 
with silver oxide and water it forms a crystallizable arsenvuyiw- 
ethylic acid, AsO(C2Hg) (OH)^ (Cahours). 

Some compounds are also known which contain both methyl 
and ethyl, but they have not been more definitely examined 
(Cahours). 



ANTIMONY COMPOUNDS OF ETHYL. 

287 Triefhylstihinc or Stiheihyl, Sb(C2Hj3. In order to pre- 
pare this compound, ethyl iodide is allowed to act on potassium 
antimonide,^ mixed with three times its weight of sand, in an 
atmosphere of carbon dioxide. The violent reaction which 
takes place must, to begin with, be moderated by cooling down 
the flask, which is afterwards gently warmed and the products 
of the reaction distilled off. In this case not only stibethyl 
but also tetraethylstibonium iodide is formed, and hence 
the crude product is rectified over potassium antimonide. It is 
perhaps better to prepare triethylstibine iodide, which will be 
hereafter described, from the crude product and to decompose 
this with zinc. Triethylstibine is also easily formed by the 
actiou of ziuc ethyl on antimony trichloride.* 

Triethylstibine is a highly refracting thin liquid possessing 

^ Potassium antimonide is obtained by igniting five parts of croani of tartar 
with four parts of antimony, when a crystalline regulus is obtained, having a 
bright metallic lustre, und containing twelve per cent, of potassium (C. Lowig 
ami E. Schweizer, Ann. Chcm, Pharm. Ixxv. 315^. 

« A. W. Hofmann, PhiL Mag. [4], xv. 147 



444 THE EIHYL GROUP. 

an unpleasant alliaceous odour, boiling at 158''*5 under a pressure 
of 730 mm. and having a specific gravity at 16"* of 1'3244, that 
of its vapour being 7*438. It fumes strongly on exposure, and 
takes fire in the presence of excess of air as well as in oxygen, 
burning with a luminous flame. By the action of alcoholic 
solution of platinic chloride on triethylstibine a fine crystalline 
compound, Pt[Sb(C2H5)3]^PtCl^, is obtained (Hofmann). 

Triethylstibine Oxide, Sh(C^H.^fi, is formed by the slow oxi- 
dation of triethylstibine in the air or under water, as well as by 
evaporating its alcoholic solution. It is best obtained by acting 
on silver oxide with an aqueous solution of the iodide or oxy- 
iodide.^ It can also be prepared by decomposing the sulphate 
with baryta water. The aqueous solution gives, on evaporation in 
a vacuum, a syrup which gradually solidifies to an amorphous 
mass. Its solution has a bitter taste and, like the alkalis, 
precipitates many metallic salts. With acids it forms salts which 
have a bitter taste, but do not act as emetics. 

Triethyl$tibi7ie Chloride, Sb(C2H5)3Clj. Triethylstibine takes 
fire in chlorine gas. In order to prepare the chloride, the oxide 
or one of its salts is treated with concentrated hydrochloric acid, 
when the above compound is precipitated as an oily liquid 
which smells like turpentine and has a specific gravity of 
1-540 at 17". 

Triethylstibine Bromide, Sb(C2H5)3Br2, is obtained by adding 
an alcoholic solution of bromine to a well-cooled alcoholic 
solution of triethylstibine, and precipitating the product with 
water. It is a colourless, highly refracting liquid, having a 
specific gravity of 1*953 at IT*, and possessing an unpleasant, 
turpentine-like smell, and on warming giving off a vajMur 
which excites te'irs and sneezing. Like the chloride, it decom- 
poses when strongly heated. Its alcoholic solution acts on 
metallic salts like potassium bromide. 

Triethylstihiiu Iodide, ^^{p^^^^^ In order to prepare this 
compound, iodine is added to an alcoholic solution of triethyl- 
stibine so long as the colour disappears. The solution is 
allowed to evaporate, and crystals separate out, which may be 
purified by recrystallization from alcohol and ether. Tliis body 
forms colourless transparent needles, which melt at 70°'5, and 
begin to volatilize at 100^ though they decompose at a tem- 
perature slightly above this. Triethylstibine iodide dissolves in 
water, and is easily soluble in alcohol and ether. It acts 

> 31erk, //»». Chem. Pharm, xcvii. 822. 



TRIETHYL8TIBINE COMPOUNDS. 446 

towards chlorine, concentrated sulphuric acid, and metallic salts 
like potassium iodide. By the action of zinc ethyl on the iodide 
a pasty mass is obtained which, on distillation, yields a heavy 
liquid, probably pentaethyl-stibine. 

TrUthylstihine Oxyiodide, Sb2(C2H5)gOl2, is formed by allow- 
ing an alcoholic solution of triethylstibine iodide, to which 
ammonia has been added, to evaporate spontaneously. It is 
also produced by the union of the iodide and oxide in alcoholic 
solution, or by adding hydriodic acid to a solution of the oxide 
in ether until a turbidity occurs.^ The oxyiodide deposits in 
hard, colourless, glassy, odourless octohedrous or tetrahedrons. 
When treated with an aqueous solution of mercuric chloride, 
the corresponding chlorine compound is fi^rmed, consisting of 
a striated crystalline, very deliquescent mass.* 

Triethylstibine Stdphafe, Sh(Gfi^.^SO^ is best obtained by 
acting with copper sulphate on triethylstibine sidphide. It is 
very easily soluble in water, and separates out from the syrupy 
solution in small white crystals. When decomposed by baryta 
water, and the filtrate evaporated, a soluble compound of tri- 
ethylstibine and baryta remains behind, which is soluble 
in alcohol ; thLs solution is decomposed by carbon dioxide 
with .formation of triethylstibine oxide.^ The basic salt, 
[Sb(C2H5)3]2(OH)2SO^ is formed by decomposing the oxyiodido 
with silver sulphate. On drying the solution in a vacuum over 
sulphuric acid, a gummy mass remains. 

Triethylstibine Nitrate, 8^02^^6)3(^03)2, is obtained by dis- 
solving triethylstibine or its oxide in nitric acid. It is easily 
soluble in water, and crystallizes in large rhombic prisms 
melting at 62°'5, having an acid reaction, and deflagrating on 
heating. The basic salt, Sb(02HJ3(OH)N03, is formed by the 
decomposition of the oxyiodide with silver nitrate, and forms 
a striated crystalline mass which is not deliquescent, though 
readily soluble in water. 

Triethylstibine Antimonite, Sb(C2H-)3(Sb0.^)j,, is obtained, 
together with the oxide, when triethylstibine is slowly oxidized. 
In order to prepare it, an ethereal solution of the latter com- 
pound is allowed to evaporate by exposure to air. The residue 
is then extracted with a mixture of alcohol and ether, and the 



* Backton, Quart. Joum. Chem. Soc. xiii. 115. 
' Strecker, Ann. Chan. Pharm. cv. 3(J8. 
> Ibid, 



446 THE ETHYL GROUP. 

antimonite obtained aa an amorphous powder, easily soluble in 
water and alcohol^ 

Triethylstibine Sulphide, ^h{0^^^, is formed by dissolving 
flowers of sulphur in an ethereal solution of triethylstibine and 
evaporating the filtrate. It is also produced by the action of 
sulphuretted hydrogen on the oxide, and forms a light crystal- 
line mass, having a silver-white colour, and smelling like mer- 
captan. It has a bitter taste, is easily soluble in water, and is 
decomposed by dilute acids with evolution of sulphurctteil 
hydrogen. When boiled with a solution of potassium cyanide, 
triethylstibine and potassium thiocyanate are produced, and its 
aqueous solution behaves towards metallic salts like potassium 
sulphide (Buckton). 

Triethyhtihine Thioantimonite, Sb(C,H5)3(SbS2)2, is obtained 
as a pale yellow amorphous precipitate when sulphuretted 
hydrogen is passed into a solution of the antimonite, and it is 
also formed when freshly precipitated sulphide of antimony 
containing free sulphur is added to an alcoholic solution of 
triethylstibine. Dilute sulphuric acid decomposes it with 
separation of antimony trisulphide and evolution of sulphu- 
retted hydrogen. 

THethyhtihitu Selcniile^ Sb(C2H5)3Se, is formed in an analogous 
way to the sulphide, which it closely resembles. 



Tetraethylstibonium Compounds. 

• 

288 These were discovered by R. Lowig,- and termed by him 
stibethylium compounds. The point of departure for these is 
the iodide obtained by the combination of ethyl iodide with 
triethylstibine. 

Ti'traethyldihonium Hydroxide, ^h(fjfi^fy^, is obtained by 
the action of silver oxide on an aqueous solution of the iodide. 
The filtrate is first evaporated on a water-bath and then in a 
vacuum, and it leaves the compound as an oily liquid which 
does not solidify, is easily soluble in water, has a strong alkaline 
reaction, and behaves like caustic potash towards the metallic 
salts, &c. 

Tetraethylstilxmium Cldoride, Sb(CoHJ^Cl, is obtained by 
neutralizing the hydroxide with hydrochloric acid. It crj's- 

* C I.<6wiji;, j4nH, Chem, Pharm, IxrxviiL 323. 
' Ann. Chrm. Pharm. xcvii. 822. 



BISMUTH COMPOUNDS OF ETHYL. 447 



tallizes in deliquescent needles, and unites with platinic chloride 
and other metallic chlorides. 

The bromide is a similar substance, but is not deliquescent. 

Tetraethylstibajiium Iodide, Sb(C2H5)J + 3H20, is obtained by 
heating ethyl iodide, triethylstibine, and water together to 100". 
On slowly evaporating the solution, the compound crystallizes 
in hexagonal prisms, but separates out in needles, when a hot 
solution is quickly cooled. This compound is always formed as 
a by-product in the preparation of triethylstibine. 

Other salts of this group have been prepared. They are 
crystal lizable, but have not been accurately investigated. 

Tctraethylstiboimcm HydrosiUphide, ^h{C'fi^^^y is obtained 
by the action of sulphuretted hydrogen on the hydroxide. It 
is an oily liquid, misciblc with water, which behaves towards the 
metallic salts like potassium hydrosulphidc. 

In addition to the above, certain Mcthyltviethylstihonmm com- 
pounds have been prepared and examined by Friedlander.^ 



BISMUTH COMPOUNDS OF ETHYL. 

289 Triethylbisviuthine, Bi(C2Hg)3, was obtained by Breed * by 
the action of ethyl iodide on an alloy of bismuth and potassium, 
and afterwards examined more particularly by Diinhaupt.* It 
is a mobile liquid having a specific gravity of 1*82, possessing a 
very unpleasant smell, and producing, when inhaled, a burning 
taste on the tip of the tongue. Exposed to the air, it evolves 
thick yellow fumes, which ignite with a slight explosion. It is 
not volatile, but if it is heated by itself it begins to decompose 
at 50** to G0°, with separation of bismuth and evolution of a 
combustible gas, and when the temperature reaches ISO*' — 160** 
a sharp explosion takes place. 

Mhyl'Bisinvih Oxide, Bi(C2H5)0, is obtained from the corre- 
sponding iodine compound by precipitation with caustic potash as 
an amorphous yellow powder, which takes fire on exposure to air. 

Ethyl'BismiUh Chloride, 'BiiG^^GU, is formed by the action 
of a warm alcoholic solution of corrosive sublimate on a dilute 
solution of triethyl bismuthine in alcohol : 

Bi(C,H^8 + 2 HgCl, = Bi(C,H,)CIj + 2 Hg(C,H5)Cl. 

^ Jaunt, PraJd, Chem. Ixx. 449. ' SilL Journ. [2], xiii. 404. 

3 Journ. Prakt. Cliem, Ixi. 399. 



448 THE ETHYL GROUP. 



On cooling, ethylmercury chloride first separates out, and 
then the mother-liquor yields on evaporation small white crystals 
of ethylbismuth chloride. 

Ethyl-Bismuth Iodide, 'R\{C^^l^ is formed by the double 
decomposition of the chloride with potassium iodide. It is 
scarcely soluble in water, and crystallizes from alcohol in yellow 
six-sided scales. 

Ethyl'BismiUh Nitrate, Bi CgHg (NOj^g, is obtained by the 
action of an alcoholic solution of silver nitrate on the iodide. 
When evaporated on the water-bath, the solution deposits basic 
bismuth nitrate, but on evaporating the liquid in a vacuum, a 
striated crystalline mass, having an unpleasant metallic taste, is 
obtained. This has a smell of rancid butter, and decomposes 
with deflagration when heated to 40^ 



BORON COMPOUNDS OF ETHYL. 

290 These compounds, discovered and investigated by Frank- 
land,^ have a special interest, inasmuch as they have not only 
led to the recognition of the quantivalence of boron, but have 
also pointed the way to a new method for determining this 
element quantitatively. 

TrU'thy/fwrine or Borethyl, 'B{G^^^, is formed by the action 
of zinc ethyl on ethyl borate (see p. 367) : 

3 Zn(C,H^, + 2 B(0C,H,)3 - 2 B(C,H^, + 3 Zn(OC,H,V 

Triethylborine is also formed when the vapour of boron 
trichloride is passed into zinc-ethyl. 

It is a colourless, easily mobile liquid, having a penetrating 
smell. Its vapour acts violently \x\yoii the mucous membrane, 
and provokes a copious flow of tears. It boils at 95*, and at 2.T 
has a specific gravity of 0*69G1, that of its vapour being 3*400. 
Wlien the vapour comes in contact with air, it forms a slight 
bluish -white smoke, which when in the dark is seen to be 
caused by a lambent blue flame. The li(|uid is spontaneously 
inflammable in air, burning with a beautiful green and some- 
what fuliginous flame. In contact with oxygen it explodes. 

Boron Didhylctharid*-, ^{O^^j^Q^l^, is formed when one 
molecule of ethyl borate is acted upon by two molecules of zinc- 
ethyl. It is a colourless, mobile liquid, possessing an ethereal 

^ Phil. Tttnis. ISdil, jwirt i. p. 107; Proc. Iloy, Sue, xxy, lfi5 (1876). 



BORON COMPOUNDS OF ETHYL. 449 

smell, and a sharp taste. It boils at 102**, and takes fire on 
exposure to the air, burning with a green, slightly luminous 
flame. The specific gravity of its vapour is 3'914. In contact 
with water it is converted into Boroii I>icthylhydr(xcide, 
6(02115)20 H, a liquid which also takes fire spontaneously, and 
decomposes on heating ; it has an ethereal smell, and a sharp, 
pungent taste. 

This latter body slowly absorbs oxygen on exposure to air, with 
formation of Boron Ethyl-hydroxethoxide, 'B(pfi^{OC^^O'B., 
a colourless and mobile liquid, which crystallizes about 8**, and 
smells like borethyl, and has a sharp taste. On treatment 
with water, it decomposes with formation of alcohol and ethyl 
boric acid, B(C2H0(OH)2, a crystalline and volatile body, pos- 
sessing an intensely sweet taste and a pleasant ethereal smell. 
When heated in a current of carbon dioxide to 100°, it sublimes 
in splendid crystals closely resembling those of napthalene. 
Although the compound has an acid reaction no salts have been 
obtained from it. 

Boron Etho-diethoxide B(C2H5)(OC2Hg)2,is formed by the slow 
action of the air on borethyl. It is a colourless liquid, which 
may be distilled under diminished pressure with only partial 
decomposition. It is decomposed at once by water with forma- 
tion of alcohol and ethylboric acid, which was first obtained in 
this way. 

jyihoron Eth<ype7Udlioodde, 'B^{0^^{OQ^^^, is formed by heat- 
ing two molecules of ethyl borate with one of zinc ethyl. It 
is a colourless mobile liquid, having a sweet taste, and a 
faint ethereal odour. It boils at 112°, and distils without 
decomposition, but its vapour-density, which was found to be 
2*78, indicates that its vapour is a mixture of ethyl borate, and 
boron ethodiethoxide : 

B2(C,Hj)(OC,H,)5 = (CjH,)B(0C2H,), + BCOC^H,),. 

Water decomposes it into boric acid, ethylboric acid, and 

alcohol. 

Ammonio^boric Ethide, B(C2H5)3NH3. Borethyl absorbs 
ammonia with avidity with formation of the above compound, 
which is an oily liquid, having an aromatic smell and an 
alkaline reaction. Carbon dioxide does not act upon it even 
in the presence of water, but it is decomposed by ax;ids. Its 
vapour-density has not been determined, although that of 
ammonio-boric methide has been ascertained, and in this case 

VOL. 111. G Q 



i50 THE ETHYL GROUP. 



tike rafOUT-dtumtj oorresponds to that of a mixture of equal 
molecules of its oompouents. From this, as well as from the 
Tapoor-demitj of the pentaethylate, it would appear that tziad 
boron mav, like the elements of the nitrogen group, occur in 
the pentatomic condition. Hence the above compounds in the 
liquid state have the following constitution : 

Ammoiiio'boroii Methide. Boron«etiiopentethoridf. 

H CH, OC.H5 OC^i 



aj J J 



H— N = B— CH, C,H,— B =- B— OC^ 

OCA OCA 



k k 



SILICON COMPOUNDS OF ETHYL. 

291 Silicon Tetraethide, Si(C,H5)^ was discovered by Friedel 
and Crafts/ and is obtained by heating zinc-ethyl with silicon 
chloride to 160^: 

2 Zn(C,H^, 4- SiCJ^ - 2 ZnCl, + SiCCjHg)^. 

The reaction is complete in three hours, and on opening the 
tube a considerable quantity of a gaseous hydrocarbon issues, 
which bums with an almost non-luminous flame. The residue, 
on distillation, yields silicon-ethyl, whilst zinc chloride and 
metallic zinc remain behind. The distillate, which also con- 
tains silicon tetrachloride and a hydrocarbon, is treated with 
water, dried, and the liquid subjected to fractional distillation. 

Silicon-ethyl is a colourless liquid, lighter than water, boiling 
at 152"* — 154**, and possessing a specific gravity of 0*8341 (Laden- 
burg), whilst the specific gravity of its vapour is 5 13. It is 
easily inflammable, and bums with a luminous flame, emitting a 
white cloud of silica. It is not attacked either by potash or 
nitric acid, and with cldorine it forms substitution products. 
In these properties it closely resembles the paraffins. It may, 
indeed, be regarded as nonane, C^H^q, in which one atom of 
carbon is replaced by silicon, and may therefore be termed 
ailico-nonane, or tetraethyl-silicomcthane. 

A Bull Soc. Chim. t. 174, 238 ; Ann. CMm. 7%ys. [4], jdz. 834. 



SILICON COMPOUNDS OF ETHYL. 451 



Silicon Hexethyl or HexethyUsilicoethane, (fifi^^i — Si(C2Hg)3, 
IS formed by the action of zinc-ethyl on silicon tri-iodide (vol. i. 
563). It is an oily liquid, in smell somewhat resembling silicon 
tetraethyl, and boiling at 250"— 253^' 

Silico-nonyl Compounds, — The chloride, SiCgHiQCl, is the first 
product of the action of chlorine on silicon-ethyl. At the same 
time other isomeric compounds are formed, from which the mono- 
chloride boiling at 185*^ can only be separated with diflSculty. It 
is, however, easy to prepare the corresponding alcohol, inasmuch 
as if the portion of the crude product, boiling between 180** and 
200^ be heated with potassium acetate and alcohol, the dichlor- 
silico-nonane present is alone attacked. An oily liquid separates 
out from the contents of the tube on addition of water, and this 
is treated with strong sulphuric acid, which leaves silico-nonjl 
chloride unattacked. The liquid, which then is still not pure, 
and boils between 180** — 190°, is heated to 180** for some hours 
with an alcoholic solution of potassium acetate, when the 
acetate is formed. This compound boils at 208° — 214°, and has 
a faint smell like acetic acid ; and when it is heated with a 
solution of potash in dilute alcohol to 120° — 130°, silico-nonyl 
alcohol, SiCgHjg-OH, is obtained. This is a liquid insoluble in 
water, having a smell like camphor, and boiling at 190.* Sodium 
dissolves in this alcohol with evolution of hydrogen, and the 
formation of gelatinous sodium silico-nonylate, which is decom- 
posed by water into the alcohol and caustic soda.* 

SHicO'heptyl Compounds. — When zinc-ethyl is allowed to act 

on ethyl silicate, a reaction takes place which, however, soon 

ceases. If sodium be added, a violent action begins even at the 

ordinary temperature, zinc separating out and a considerable 

evolution of gas occurring. The following products are thus 

obtained : 

B.P. 
Ethyl orthosilicopropionate, SiCaH^COCgHg), 166°-5 

Diethyl silicon-diethyl-oxide, Si(C2H6)2(OC2H5)2 159* 

Ethyl silocoheptyl-oxide, Si(C2H5)30C2H5 155°-5 

Silicon ethyl, Si(C2H5), 153* 

Silicoheptane, SiCCgH^aH lOr 

Silicoheptane or TriethylsUico-methane, Si(Gfi^fi, is the last 
product of the above reaction, and is formed, together with 

* Friedcl and Ladenburg, Ann, Chim, Phys, [5] xix. 890. 

- Friedel and Crafts, Compt, Rend, Ixi. 792 ; Ann, Chem, Pharm, cxzxviii. ID. 

O G 2 



452 THE ETHYL GROUP. 



silicon ethyl, from the ethyl silicoheptyl-ozide, this giving off 
oxygen and ethylene. It is a colourless liquid boiling at 107", 
having a specific gravity of 07510 at 0**, and possessing a smell 
resembling the petroleum hydrocarbons. It is insolahle in 
water and in concentrated sulphuric acid, does not undeigo 
alteration in the air, and is easily inflammable, burning with 
a luminous flame. The specific gravity of its vapour is 4*1. 

This compound contains one atom of hydrogen in direct com- 
bination with silicon, and Lence this should possess the pn>- 
j>erties of the hydrogen in silicon hydride ; and this is, indeed, 
the case, for whilst silicon ethyl or silicononane is not attacked 
by fuming nitric acid, silicoheptane is oxidized at once with 
explosive violence by this acid. 

292 Siiicohqyii/l Alcohol ox Tricthi/kUicol, SiiC^^^OH. Tliis 
singular compound is of great theoretical interest, as it is the first 
example of a silicon alcohol. It is a tertiary alcohol which not 
only in its constitution, but also in most of its properties, may 
bo considered to be triethyl-carbinol, in which one atom of 
carbon has been replaced by silicon. It is obtained by the 
action of the corresponding chloride on dilute ammonia ; 

Si{(ljr,)3Cl + NH3 -h H^O = SiCC^HjjOH 4- JsH.Cl. 

Triethylsilicol is a colourless thick liquid, insoluble in water, 
having a strong smell resembling camphor, boiling at 154", and 
having a si)ooific gravity of 0*8709 at 0^ and a vapour density 
of 4 07. It is easily combustible, burning with a luminous 
flame, and leaving a residue of silica. When treated with 
fuming suli)liuric acid the following decomposition occurs : 

(C^HJ^SiOH + SO3 = C.H^SiO.H + 2 C.H, -f H, + SO^ 

This oxidation is very similar to that which the tertiary 
alcohols undergo. 1 ho silicopropionic acid, which is formed 
at the same time, will be described hereafter. 

Silicol forms with sodium the very deliquescent compound 
(C2Hg)3Si.ONa. If carbon dioxide be passed into an ethereal 
solution of silicol, another amorphous delitiuescent compound, 
(OjHJjSi.O.CO.ONa, is deposited. Tliis sodium silicoheptyl 
carbonate leaves, on ignition, a residue of pure sodium 
carbonate : 

2 (C JI,)3SiC0,Na = [c'h 'hsi } ^ + ^^^« + NasC03. 



ETHYL SILICOHEPTYL OXIDE. 453 



Ethyl SUicoheptyl Oxide ) (C2Hg)3Si \ q . , , . , ^^^^^, 
or Tridhyldlican Ethylate, ] C^Hg J ^' ^^ ^^^ ^^"^"^ product 

of reduction of ethyl silicate. It is a pleasantly smelling 
liquid, boiling at 153°, insoluble in water, and undergoing 
no change on exposure to air. WTien heated with acetyl oxide 
(acetic anhydride) for some time in closed tubes to 250°, the 
following reaction takes place : 

^^h)^^ I () J. C2H3O I Q _ (€2115)381 ) Q , C2H5 \ ^ 

C2H5 1 ^ + aH30 J ^ - C2H3O / ^ + C2H3O / ^- 

The silicoheptyl acetate thus formed is a liquid boiling at 
168°, and having a pleasant ethereal smell, resembling at the 
same time camphor and acetic acid. By heating it with a 
solution of sodium carbonate it is converted into triethyl- 
silicol. 

Silicoheptyl Oxide y /n^i i^\^g- \ 0- This ether was discovered 

by Friedel and Crafts, and obtained as a by-product in the 
preparation of silicon-ethyl.^ It was afterwards obtained by 
Friedel and Ladenburg, by acting with zinc-ethyl on silicon oxy- 
chloride, SigClgO.^ It is also obtained from triethyl-silicol by 
removing from this body the elements of water, either by means 
of sulphuric acid or phosphorus pentoxide. It is likewise 
formed by the action of caustic potash on silicoheptyl chloride, 
and, lastly, by heating ethyl-silcoheptyl oxide with hydriodic 
acid : 

«> ^1(02X15)3 1 o 4- 2 HI = ^^(^2^5)3 lo4-2r!HT4-HO 

It is a thick, colourless, almost odourless liquid, boiling at 
231°, and having at 0° a specific gravity of 0*8590. 

Silicohejytyl Chlaride, (00115)38101, is formed by heating ethyl 
silicoheptyl oxide with acetyl chloride for some hours to 180° : 

^^'^0 ^' } O + C2H3OCI = (C2H5)3SiCl + ^2^|p^ } O. 

It is a colourless liquid, fuming on exposure to air, and 
possessing a penetrating camphor-like smell, and burning with 
a luminous green-mantled flame. It boils at 143°*5, has a 
specific gravity at 0° of 9249, and is slowly decomposed by 
water. 

* Ann, Chcm. Pharm, cxzzTiii. 19. * Ibid. czlTii. 855. 



454 THE ETHYL GROUP. 



Silicoheptyl Bromide, (C^^^iBx, Bromine acts violently 
on silicoheptane, and hence it must only be added drop by 
drop, and the mixture well cooled. The bromide is a liquid 
boiling at 161°, and possessing properties analogous to the 
chloride. 

SiHcon-duthyl Compounds. When equal molecules of ethyl 
silicate and zinc-ethyl are heated in a closed tube with sodium 
the chief product consists of silicon dicthyl-ether or diethylsiliconr 

diethylate, Si(C2R^2i^^2^5)r "^^^^ ^^ ^ pleasantly smelling 
liquid, boiling at 155°-8, and having at 0*" a specific gravity 
of 0'87o2, and a vapour-density of 602. 

When heated with an acid chloride under pressure, the oxy- 
ethyl groups are replaced one after another by chlorine. The 
compound which is first formed, (C2Hg)2Si(OC2H5)Cl, is a liquid 
fuming strongly in the air, boiling between 146** and 148*, and 
being slowly decomposed by water. DicthylsHicon diMaride, 
(02115)281012, boils at 128** — 130°, possesses a smell resembling 
silicon chloride, and, like this compound, fumes in the air, and 
is decomposed by water with formation of diethylsiUco-ketone, 
(02115)2810. This latter compound, previously obtained by 
Friedel and Crafts by the oxidation of silicon-ethyl, is also 
formed when silicon-diethyl ether is heated with hydriodic acid : 

Si(C,H5),(0C,H,), + 2 HI = Si(C,H,),0 + 2 C,H,I + H,0. 

It is a deliquescent syrup, insoluble in water, which can 
be distilled at a high temperature without decomposition. 
At —15° it does not solidify, and it is a substance possessing few 
characteristic properties. 

Silicon-monethyl Compounds. The first product of the action 
of zinc-ethyl and sodium on ethyl silicate is monethyl silicic ether ^ 
or orthosilico propionic ether, 02X1581(002115)3. This body was 
discovered by Friedel and Ladenburg,* and prepared in a similar 
way by the action of zinc-ethyl and sodium upon triethylsilicO' 
chloroformate, Si01(OC2H5)3. It is a pleasantly smelling liquid, 
boiling at 159**, and having a vapour-density of 6'92. When 
heated with acetyl chloride under pressure it forms ethylsUicon 
trichloride, 021^581013, a strongly refracting liquid, boiling at 
about 100**, which is decomposed by water with violence into 
silicopropionic and hydrochloric acids. 

C2H5SiCl3 + 2H2O = CjH^SiOjH 4 3HC1. 

' Ann, Chem, Pharm. cxiiz. 259. 



COMPOUNDS OF ETHYL WITH THE METALS. 466 

Silicopropionic acid, which is thus formed, is also produced 
by warming ethyl orthosilicopropioDate or diethyl silico-ketone 
with concentrated potash. A better plan, however, is to warm 
the ortho-ether with concentrated hydriodic acid : 

C^jHgSiCOC^H^), + 3 HI = C^H^SiO.OH + 3 C^Hgl + H,0. 

It is a white amorphous powder, which on heating becomes 
incandescent, leaving behind silica containing finely divided 
carbon. The acid is soluble in caustic potash, and is precipi- 
tated from the solution either by hydrochloric acid or by sal- 
ammoniac. 

Ethyl silicate is not attacked at the ordinary atmospheric 
pressure when heated with zinc-methyl and sodium. If, however, 
ethyl silicate be heated with zinc-methyl gradually to 300** in 
closed tubes, ethyl orthosilic(Hicetate, CH3Si(OC2Hg)j, is formed. 
This is a liquid boiling between 145** and 151**, and which, when 
heated with hydriodic acid, is converted into ortJiosilic(Hicetie 
add, CHjSiO.OH, a body which closely resembles orthosilico- 
propionic acid.* 



COMPOUNDS OP ETHYL WITH THE METALS. 

Beryluum Ethide, Be(C2Hg)2, 

293 Is formed by heating crystallized beryllium with mercury- 
ethyl to 130°. It is a colourless liquid, which fumes in the 
air, and takes fire when slightly warmed. It boils at 185° — 
188**, and is decomposed by water with violence, beryllium 
hydroxide being produced.^ 

Magnesium Ethide, ^giC^B.^^ 

Is formed by heating ethyl iodide with magnesium filings to 
120** — 130**. It is a colourless, very mobile liquid, possessing 
a strong alliaceous odour. It takes fire when exposed to 
air, and is violently decomposed by water with formation of 
magnesium hydroxide.* 

^ Ladenbnrg, Ann. Chem. JPharm, clxxiii. 143. 

* Cahours, Compt, Rend. IxzvL 

> Cahoara, Ann, Chim. Phya. [8], Iviii. 5. 



456 



THE ETHYL GROUP. 



Zinc Etuide, or Zinc-Ethyl, Zn(C^^^ 

294 This important compound, which has ah-eady frequently 
been mentioned, was discovered on the 1 2th June, 1849, by Frank- 
land,' in Bunsen's laboratory in Marburg, at the same time as 
zinc-methyl. He obtained it by heating ethyl iodide with an 

excess of finely granulated zinc in a strong 
tube drawn out to a capillary point, as in 
Fig. 89. As soon as the zinc is introduced, 
the tube is drawn out, as shown in the 
figure, and then it is warmed, and the point 
a dipped into ethyl iodide, which, when the 
air cools, rises into the tube. This is then 
boiled so as to drive out the air, and again 
inserted into the iodide, the requisite quantity 
of which can then be introduced. The tube 
is melted off at the point b, and as soon as 
the reaction is complete, the point is softened 
in the flame of the blowpipe, and the gases 
allowed to escape as gradually as possible. 

This method is, however, not adapted for 
preparing zinc-ethyl on a large scale, as the 
employment of glass tubes of sufficient 
dimensions under so high a pressure is 
accompanied by considerable danger. Frank- 
land, who was then Professor in Owens 
College, obtained from James Nasmyth an apparatus of such 
strength that the preparation of the substance could be con- 
ducted on a large scale without fear of explosions occurring. 

This apparatus although not now used in the manufacture 
of zinc-ethyl merits description as having done good service, 
and being of historical interest. It consists of a tube of wrought 
copper (a, Figs. 90, 91) 45 cm. in length and 3 cm. internal 
diameter, the sides being 1*25 cm. in thickness. This tube 
is closed at bottom by a screw-plug, and is furnished at top 
with a brass flange {b b), which can be closed by the brass cap 
(dd), which screws on to a lead collar. A stopcock placed in 
the position of the screw-plug (c) serves as an outlet for the 
generated gases or fur distilling off the liquid formed. This 
digester is heated by means of a cylindrical oil-bath (Figs. 92 
and 93) heated by a suitable gas-lamp. 

» Chem, Soc, Joum, iL 2»7 ; Phil. Trans, cIxt. 259. 




Fio. 89. 



ZINC ETHIDE. 



457 



An equal volume of auhydrous ether was added by Franldand 
to the ethyl iodide, as this accelerates the reaction, prevents 
the formation of large quantities of gaseous products, and largely 
increases the yield of zinc-ethyl (Brodie).^ 

Pebal * afterwards found that zinc which had been once acted 
upon by ethyl iodide, or which had been washed with sulphuric 
acid, attacked the iodide under the ordinary atmospheric pres- 
sure, Rieth and Beilstein ^ employed in place of zinc an alloy 
of this metal with sodium, obtained by heating 4 parts of zinc 
to the boiling-point and then adding 1 part of sodium, the 





Fig. 90. 



Fig. 91. 



whole being well mixed, poured out, and when cold the outer 
layer cut off, and the last traces of free sodium being got rid of 
by washing with water. It is not necessary in this case to add 
ether. Beilstein and Alexejeff* afterwards noticed that the 
reaction takes place easily when a mixture of one part of this 
alloy is heated with 8 parts of zinc turnings and 10 parts of 

^ Joum, Chcm, Soc. iiL 409. 

* Ann, Chcm, Pharm. cxviii. 22 ; cxx. 194 ; cxxi. 105. 

* Ann, Chcm, Pharm, cxxiii. 245 ; cxxiv. 248. 

* Zeitsch. Chem, 1864, 101 ; BuU, Soc Chim, [2], ii. 51. 



THE ETHYL GROUP. 



ethyl iodide. Wichelhau3 ' found that the addittoa of the alloy 
is not necessary, and recotnmeDds zinc to be used in the form 
of coarse tilings. Chapman ^ has shown that the reaction takes 




place more quickly if to the mixture a small quantity of dno- 
eth;l be added. 



In order to prepare zinc-ethyl according to one of the latter- 
mentioned metliods the apparatus Fig. 94 is used, aJready de- 
scribed under Zinc-methyl (see p. 248). This is filled with carbon 
dioxide, and aliut o£F at C with a small quantity of mercury. 
It is heated in a water-bath so long as the iodide of ethyl ia 
condensed in the receiver, and continues to run back into the 
flask, this process generally lasting from two to three hours. 
The gases which are continually evolved escape through the 




short column of mercury. They consist, according to Beilstein 
and Rieth, of a mixture of ethane, ethylene, and butane, 
formed by the action of iodide of ethyl on the zinc-ethyl, and 
their quantity is considerably increased if the zinc is not 
present in excess. In order to carry out the operation success- 
fully it is absolutely necessary that no trace of moisture shall 
be present either in the materials employed or in the apparatus, 
as othei-wise the reaction is much retarded. Extraordinary 
care, therefore, in freeing the materials perfectly from mobture 



460 THE ETHYL GROUP. 




is amply repaid in the increased quantity of the product 
(Frankland). When the reaction is complete, the flask con- 
tains a solid mass consisting of excess of zinc together with a 
compound of zinc-ethyl and zinc iodide, having the composition 
Zn(C2H5)I. The flask is then connected with the upper part 
of the condenser, and placed in a paraffin- or oil-bath, a current 
of carbon dioxide being led in through the stopcock A, and the 
zinc-ethyl which distils over being collected in a vessel provided 
with a mercury valve. The whole must be at last heated to 
180** in order to decompose the above-mentioned compound : 

The method proposed by Gladstone and Tribe ^ for the 
preparation of zinc-methyl (p. 246) is also recommended for that 
of zinc-ethyl, as the following experiment shows. Ninety grams of 
zinc fllings and 10 grams of reduced copper are placed in a flask 
of 300 cc. capacity, and heated over the flame of a ]^unsen s 
burner for about five minutes until the whole consists of dark- 
grey small granular masses, care being taken not to heat the 
metals so as to form an alloy. The mass is then allowed to cool, 
and 87 grams of ethyl iodide added, and the whole warmed in 
connection with a reversed condenser to 90^ when in a few 
seconds the reaction begins, and is completed in fifteen minutes. 
On heating in the oil-bath, in an atmosphere of hydrogen, the 
distillation of zinc-ethyl began at 160®, and after an hour the 
whole had passed over. In this way 31 grams was obtained 
instead of the calculated quantity, 34*3, or 90 4 per cent, whilst 
in the older operations not more than 80 per cent, of the quantity 
is obtained. 

An improved method of preparation now employed in 
Professor Frankland's laboratory is first to heat the zinc filings, 
after they have been washed with acid, stroDgly in a glass 
flask, so as to decompose all the hydroxide. Next, to add an 
equal weight of ethyl iodide and a single crystal of iodine, and 
heat gradually to about 90** with a reversed condenser. As 
soon as no ethyl iodide is seen to run back, the whole is allowed 
to cool, and a bent tube is attached to the flask, the zinc-ethyl 
being distilled from an oil-bath. In this way zinc-ethyl can 
be easily prepared in any quantity. 

Properties, Zinc-ethyl is a colourless, mobile, highly re- 

* Joum, Ch4m. Soe, 1879, L 671. 



ZINC-ETHYL COMPOUNDS 461 



fracting liquid, possessing a peculiar but not unpleasant smell, 
boiling at 118**, and having a specific gravity of 1*182 at 18". 
It takes fire at once on exposure to air, burning with a luminoiis 
green-mantled flame and evolving dense white fumes of zinc 
oxide. If a porcelain capsule be held in the flame, a black 
spot of metallic zinc is formed, surrounded by a deposit of the 
white oxide. Zinc-ethyl takes fire instantly in chlorine, burning 
with a pale smoky flame. When brought in contact with bromine, 
a violent explosion occurs ; but when the action is moderated, 
ethyl bromide and zinc bromide are formed. Iodine acts in a 
similar way, and if ether be not employed as a diluent a violent 
decomposition takes place with evolution of light and heat. 

Zixc-Ethvl COMrOUNDS. 

295 ZinC'EthyUEthoxride, C^^ZnifiGfi^. When dry oxygen 
is passed into an ethereal solution of zinc-ethyl it is absorbed, 
and the vessel becomes filled with thick white vapours, which 
disappear as soon as one atom of oxygen has been employed for 
every molecule of zinc-ethyl. The compound, which is in- 
soluble in ether, has not been accurately studied. It appears 
also to be formed by the action of zinc-ethyl on absolute alcohol* 
Water decomposes it according to the following equation ; 

^° { O'^k + 2 H,0 = Zn I gg + HO.C,H, + C,H,. 

By the further action of oxygen on the ethereal solution of 
zinc-ethyl, zinc-cthoxide or zhic didhylate, Zn(OC2H5)2.^ a com- 
pound already mentioned, is formed as a white powder, which 
is decomposed by water with evolution of gas. 

Zinc-amine. If dry ammonia be passed into an ethereal solu- 
tion of zinc-ethyl, ethane is evolved, and zinc-amine, Zn(NH2)2, 
is produced in the form of a white amorphous precipitate : 

Zn{g;g; + 2NH3=Zn{^H^ + 2C,H,. 

Water and alcohol decompose this compound instantly, with 
formation of ammonia. When heated with ethyl iodide to 150* 
diethylammoniumiodide is produced. At a red-heat zincamide 
decomposes into ammonia and zinc-nitride, NgZuj, a grey non- 
volatile infusible powder, which decomposes water with forma- 
tion of ammonia with such energy that it becomes red-hot on 
being moistened. 

* Lissciikc, Zcitsch. Chcm 1864, 678. ' Frankland, Phil. Trans, 1855, 267. 



462 THE ETHYL GROUP. 



If zinc-ethyl and diethylamine be heated together, zinc- 
di ylamine^ Zn j ^(C^H*)*' ^ produced, and is a body re- 
sembling zincamine in properties. 

Sodium Ethide. 

296 If one part of sodium and 10 parts of zinc-ethyl be brought 
together at the ordinary temperature, the sodium dissolves after 
some days completely, and an equivalent quantity of zinc is 
precipitated. On distiUing off the excess of zinc-ethyl from the 
clear thick liquid in a current of hydrogen, the compound, 
NaCjHg 4- Zu(Cfi^^ is obtained in crystals melting at 27*. All 
attempts to prepare pure sodium-ethyl from this have as yet 
proved unsuccessful. When gently warmed, decomposition takes 
place, zinc and sodium remaining behind and hydrocarbons 
being evolved. If the compound be heated with sodium in the 
water-bath it also decomposes easily. On exposure to air it at 
once takes fire, burning with almost explosive violence.' If 
ethyl iodide be added to its solution in zinc-ethyl, the following 
reaction takes place : 

NaCjHg + C,H,I =1 Nal + C^H, + C^He- 

This explains why sodium-ethyl is not produced when 
sodium is heated with ethyl iodide, as this substance, when 
formed, is at once decomposed by the excess of ethyl iodide 
according to the above equatioD.* 

Sodium ethide absorbs dry carbon-dioxide with formation of 
sodium propionate (Wanklyn). Potassium acts on zinc-ethyl 
even more powerfully than sodium does, a double compound 
analogous to the preceding being obtained. 

Cadmium Ethide, CdCC^Hg)^ 

Is formed by heating cadmium with ethyl-iodide, when the 
compound of the metallic iodide with cadmium-ethyl is obtained, 
and this is decomposed at a temperature between ISO"" and 220^ 
at which temperature, however, the cadmium-ethyl undergoes 
partial decomposition. It is a colourless liquid, resembling zinc- 
ethyl, is spontaneously inflammable, and bums with the evolution 
of brown fumes.^ 

^ Frankland, I^roc Roy. Soc yiii. 602. 

« M'anklyn, Phil. Mag, [4], XTii. 226. 

• Frankland, Prce. Roy Soe. ix. 845. 

« Wanklyn, QuaH. Joum, Cktm. Soe, iz. 193. 



MERCURY ETHIDE. 463 



Mercury Ethide, B.giCJi^)^ 

297 Was first prepared by Buckton,^ by the action of mercuric 
chloride on zinc-ethyl. It is now obtained by a much more 
simple reaction, according to the method of Frankland and 
Duppa.^ For this purpose a mixture of one part of ethyl acetate 
and ten parts of ethyl iodide is shaken up with sodium amalgam 
containing 0*2 per cent, of the former metal : 

Hg + Na, + 2 aH,I = Hg(C,H,)2 + 2 Nal. 

In this case the flask must be dipped frequently into cold 
water, in order that the temperature may not rise too high. 
When a sufficient quantity of sodium iodide has been formed 
to render the mass thick, the acetic ether is distilled off from a 
Avater-bath, together with the excess of ethyl iodide, and this 
mixture used for a second operation. Water is then added to 
the residue. The mercury ethide which separates out is 
separated from the liquid and treated with alcoholic potash, 
washed with water, dried over chloride of calcium and rectified. 
The part which the acetic ether plays in this reaction is not 
understood. No reaction takes place, however, unless it be 
present, even when ethyl-ether is used. On the other hand, the 
othyl acetate may be replaced by ethyl formate or methyl acetate. 
None of these ethers appear to suffer any alteration, and it is, 
moreover, remarkable that this reaction takes place the more 
readily the smaller the quantity of sodium present in the 
amalgam. Mercury ethide is a colourless liquid, having a 
peculiar but not unpleasant smell, boiling at 159**, and having 
a specific gravity of 2*444, that of its vapour being 9*97. It 
is easily inflammable, burning with a luminous flame, and giving 
off vapours of mercury. It is poisonous, but acts much less 
•violently than mercury methide, inasmuch as it is less volatile. 

At the ordinary temperature sodium acts slowly on mercury 
ethide, giving rise to a grey spongy mass which takes fire on 
exposure to air, and explodes under the most trifling change 
of condition. When gently warmed, it yields a mixture of 
ethane and ethylene, from which it would appear that this body 
contains sodium-ethyl (Buckton ; see p. 462). 

When mercury ethide is heated in a closed vessel with granu- 
lated zinc to 100**, it is completely converted into zinc-ethyl. 
Cadmium acts only slowly and incompletely on it. Bismuth, 
on the other hand, acts on it somewhat easily with formation 

of triethyl-bismuthine. 

' Joum, Chcm. Soc, xvL 17. ' Joum, Chem. Soe, xvi. 415. 



ALUMINIUM-ETHYL. 4G5 



it yields butane, or its products of decomposition, and mercury 
iodide. 

Merciiry-Ethyl SidplMte, (C2H5Hg)2SO^, is formed, together 
with pure ethane, by the action of concentrated sulphuric acid 
on mercury-ethyl. It crystallizes from alcohol in silvery-white 
scales (Buck ton). 

Mercury-Ethyl Nitrate, CgHjHgNOg, is obtained by acting 
upon the base wdth nitric acid, as also by the decomposition 
of the iodide with silver nitrate. It is easily soluble in water, 
less so in alcohol, and crystallizes in transparent prisms, which 
on heating decompose with slight deflagration. 

Mercury-Ethyl Cyanide, CgHjHgCN, is obtained by saturating 
the hydroxide with alcoholic hydrocyanic acid. It deposits 
in large crystals which are very volatile and when heated emit 
an intolerable odour. The vapour violently attacks the 
mucous membrane, and the compound appears to be very 
poisonous. 

Mercury-Ethyl Sulphide, {O^^g)^, is precipitated in the 
form of a yellowish-white powder by the action of ammonium 
sulphide on an alcoholic solution of the chloride. It is soluble 
in an excess of the precipitant as well as in ether, and, when 
the ether is allowed to evaporate, separates out in the crystalline 
form. 

In addition to the above, many other mercury-ethyl compounds 
have been prepared. 

Aluminium-Ethyl, A1(C2H5),. 

299 The first observations on this compound were made almost 
simultaneously by Cahours ^ and by Hallwachs and Schafarik.2 
It is, however, to the investigations of Buckton and Odiiug' 
that we owe our more exact knowledge of this body. It is 
obtained by heating mercury-ethyl with aluminium foil to 100°. 
A colourless liquid is thus obtained, which fumes in the air, and 
even takes fire w^hen exposed to the air in thin layers, burning 
with a bluish-red-mantled flame. The compound boils at 194°, 
and the specific gravity of its vapour at 234° is 4 5, whereas 
that corresponding to the above formula is 39. Hence it would 
appear this body does not possess a constitution similar to 
that of aluminium chloride. Water decomposes it with great 

* Ann. Chim. Phys. [3], Iviii. 6. • Ann. Chcm, Pharm. cix. 206. 

' Proc. Bfiy Sor. xiv. 19. 

VOL. III. H H 



460 THE ETHYL GROUP. 




violence ; iodine converts it into ahiminium-cthyl iodide^ 
AlgCCgHg^glg. This compound can also be obtained by heating 
aluminium with ethyl iodide. It is a colourless, unpleasantly- 
smelling liquid, fuming in the air, and boiling at 340"* — 350°, 
and being likewise decomposed by water. 

When dropped into a vessel filled with oxygen or chlorine it 
takes fire, burning with a violet light. 

Compounds of Lead with Ethyl. 
300 Of these two are known : 

Lead Tetraethyl. Lead Triethyl. 

The formula of the first of these compounds points out that 
lead acts as a tetrad element towards the positive elements or 
radicals. In its compounds with the negative elements, how- 
ever, it acts as a diad, as is shown by the fact ascertained by 
Roscoe,* that the vapour-density of lead chloride corresponds to 
the formula PbClg. In lead-triethyl, on the other hand, two 
atoms of metal are connected together by one combining unit. 

Lead-Tdraethyl, Vh(f^^^^, is formed, together with lead tri- 
ethyl, by the action of ethyl iodide on an alloy of lead and 
sodium. It may be more readily obtained in the pure state 
by treating zinc-ethyl with lead chloride.* Frankland and 
Lawrance* recommend the following plan. Dry lead chloride 
is added to zinc-ethyl, contained in a thick glass vessel, until no 
further action takes place, the whole being stirred with a glass 
rod. Metallic letitl then separates out in a s{)ongy form : 

2PbCl, + 2Zn(C2Hj2 = PKf'2H5)4 + Pb + 2ZnCl^ 

The product is carefully mixed with water, and subjected to 
distillation. 

Lead-tetraethyl is a colourless, slightly smelling liquid, having 
a specific gravity of 1*62^ and boiling at about 200** with partial 
decom|x>sition and separation of lead. Lender a pressure of 
11)0 mm. it may be distilled without decom{)osition at 152^ 
and it may also be volatilized in a current of ste^im without 

^ Proc. Roy. Soc. xxvii. 426. 

' Hurkton, Chui. Uaz, 1858, 415 ; Pmc. Rmf, !\oc, ix. C85 ; Cahours, Ann. 
Chim. Vhys. [«]. Ixii. 257. 
• Joum. rhtm Stw. isri). i •JH. 



LEAD-ETIIYL COMPOUND& 4G7 



the slightest decomposition occurring. It is easily inflammable, 
burning with an orange-coloured, blue-mantled flame, emitting 
clouds of lead oxide. It is not attacked by ammonia, carbon 
dioxide, carbon monoxide, cyanogen, oxygen, nitric acid, or 
sulphuretted hydrogen ; but it absorbs sulphur dioxide quickly, 
with formation of diethyl-sulphone and lead-diethyl sulphonate 
(Frankland and Lawrance) : 

PKCjHs), + 3S0, = (C,H^,SO, + (C,H,.SO^,Pb. 

Weak acids do not act upon it. Concentrated acids, on 
the other hand, decompose it with formation of lead-triethyl 
compounds and ethane. 

Lead'Triethyl, V\{C^^q^ is easily formed by the action of 
ethyl iodide on an alloy of lead and sodium.^ For its prepara- 
tion the best mode is that suggested by Klippel.^ Three parts 
of lead are fused in a crucible, which is then withdrawn from 
the fire, and one part of sodium added, the whole being stirred. 
The crucible is then filled with sand, and allowed to cool slowly. 
In this way a fine crystalline alloy is obtained, and this, having 
been finely powdered, is placed in a flask connected with an 
inverted condenser, the mass having been previously moistened 
with ethyl iodide. A violent reaction takes place, and lead- 
triethyl is formed, which is then extracted with ether. 

Lead-triethyl is a mobile liquid insoluble in water, only 
slightly soluble in alcohol, but readily so in ether, having a 
specific gravity at 10" of 1*471. Heated alone it undergoes 
decomposition, but it volatilizes slightly in an atmosphere of 
ether. The vapours of this body attack the mucous mem- 
branes with great violence, exciting a flow of tears (Klippel). 
On exposure to light, as well as on heating with .water, it 
decomposes with separation of lead. 

Lecul'Ethyl Coinpmtiids. If iodine be slowly added to a solu- 
tion of lead-triethyl in alcohol and ether, the unstable iodide, 
(C2H5)3PbI, is formed, and this, when treated with freshly 
precipitated oxide of silver, yields Icad-cthyl hydroxide^ 
{C^^^hOU, This hydroxide is also obtained, according to 
Cahours, by the distillation of the chloride with solid caustic 
potivsh. The oily distillate solidifies after some time to a crystal- 
line mass, possessing a slight but peculiar odour provocative 
of sneezing. It is slightly soluble in water, and easily so in 

^ I-owig, Joum, Prdkt, Chcm. Ix. 304. 
- Jonrn. Prakt. Chcm. Ixxxi. 287. 

H n 2 



468 THE ETHYL GKODP. 



alcohol and ether. Its solution has a strono: alkaline reaction 
and a sharp caustic taste, giving rise to an unpleasant sensation 
in the throat. Like caustic potash, it saponifies fats, and, even 
at the ordinary temperature, it is slightly volatile, and for this 
reason it produces white fiimes when brought into contact with 
hydrochloric acid. It decomposes ammouiacal salts, and pre- 
cipitates the salts of many metals. 

Lead'Eihyl Chloride, (C2Hj3PbCl, is obtained by heating lead* 
tetraethyl with hydrochloric acid : 

(C^HJ.Pb + HCl = (C^HJjPbCl + C^H,. 

If the action be continued too long a further decomposition 
occurs, and lead chloride is formed (Cahours). Lead-ethyl 
chloride is easily soluble in alcohol and ether, crystallizing in 
long bright needles, which when warmed emit a mustard-liko 
smell, and when more strongly heated decompose with detonation. 

Lead-Ethyl Sulphate, [(C^HJjPbJ^SO^, is obtaineil by the 
action of dilute sulphuric acid on the solution of the base. 
It is a white precipitate, which is only slightly soluble in water, 
but dissolves in alcohol if free sulphuric acid be present, and 
crystallizes from this solution in hard glistening octohedrons. 

Lead-Ethyl Nitrate is formed when an ethereal solution of 
lead-triethyl is brought in contact with an alcoholic solution of 
silver nitrate : 

(aHJ.Pb, + 2 AgN03 = 2 (C,H^3PbN03 + 2 Ag. 

The nitrate remains on evaporation as a thick liquid, having 
a butter-like smell. This on standing solidifies to a saponaceous 
mass, which detonates on heating. 

Lead-Ethyl Carbonate, [(02H^)3Pb]2C03, is obtained in small 
hard glistening crystals by allowing the alcoholic solution of the 
base to evaporate spontaneously. It is scarcely soluble in water, 
has a strong burning taste, and can be recrystallized from ether. 

Lead- Ethyl Cyanide, {C^^^hC^, is formed by heating the 
chloride with alcohol and potassium cyanide in closed tubes to 
100^ It forms a blood-red liquid, which on the addition of 
water yields a white precipitate, and this can be obtained crys- 
tallized in fine prisms from an ethereal solution. 

Lead-Ethyl Thiocyamte, (C^jHJjPbSCN, is prepared by heat- 
ing the chloride with silver thiocyanate. It is soluble in water, 
alcohol, and ether, and crystallizes from the last solvent in prisms 
resembling those of potassium thiocyanate. 



COMPOUNDS OF TIN WITH ETHYL. 469 

In addition to the salts of lead-ethyl above described, other 
compounds with both inorganic and organic acids liave been 
prepared. 

Compounds of Tin with Ethyl. 

301 The following compounds of tin and ethyl are known: 
(1) (2) (3) 

Tm-Tetraethyl or Tin-Triethyl or Tiu-Diethyl or 

Stannic Ethide, Stiinnoso-Stannic Ethide. StHnnoos Ethidc. 

SnCC^H^, Sn/O^H,)^ Sn,(C,H^, 

Of these the first corresponds to tin tetrachloride, and the last 
to tin dichloride. As the molecular formula of the last-named 
substance has been shown by Victor Meyer ^ to be SuoCl^ from 
its vapour-density determination, we must assume that in the 
stannous compounds the two atoms of tin are connected by 
double linkage, whilst in the triethyl compounds a single link- 
ing only exists. 

Tin-Tdraethyl or Stannic Ethide, Sn(CoHg)^, is obtained 
by the action of zinc ethyl on tin tetrachloride,- tin-triethyl 
iodide, or tin-diethyl di-iodide.^ It is, however, best obtained 
by gradually adding fused anhydrous stannous chloride to zinc- 
ethyl, until the latter has been almost completely decomposed. 
The mass is then distilled in an oil-bath, the liquid distillate 
treated with water and dilute sulphuric acid, washed with 
water, dried, and rectified over chloride of calcium.* In this 
process tin-diethyl is first formed, but this easily decomposes, 
as Cahours has shown, into tin and tin-tetraethyl.^ 

Stannic ethide is a colourless liquid, having a slightly ethereal 
odour, boiling at 181°, possessing a specific gravity of 1*187, 
while that of its vapour is 8021 (Frankland). It is very in- 
flammable, burning with a luminous blue-mantled flame, and 
emitting clouds of stannic oxide. In oxygen it burns with 
a very bright white flame. Neither sodium, magnesium, nor 
aluminium acts upon it at its boiling point ; nor is it attacked 
in the cold either by ammonia, carbon dioxide, carbon monoxide, 
cyanogen, nitric oxide, oxygen, or sulphuretted hydrogen. 

Tin- Triethyl or Stannoso-Stannic Ethidc, Sug^CgHg)^ is 

' Bfr. Deutsch. Chem. Ges. xil. 1195. 

2 Buckton, Phil. Trans. 1859, 426. > Buckton. ift. 424. 

* Fmnkland and Lawrance, Joum. Chevx, Soc. 1879, i 130. 

* Ann. Chrin. Phann. cxiv. 227 and 354. 



TIN-TRIETHYL COMPOUNDS. 471 

small quantity of alcohol. The reuidue Is then purified by 
distillation. 

Tin-triethyl iodide ia a colourless liquid Itavingaveryptuigeat 
smell. It boils at 235° — 238°, and at 22° has a specific gravity of 
1833. It forms a crystalline mass vrhen cooled in a mixture 
of ether and carbon dioxide. It combines with ammonia to 
form tin-friethi/l-aiitinoniuni-iodide, (CjHj)jSnNHgI, a compound 
soluble iu water and alcohol, and crystallizing in long prisms. 
On heating this melts, and may be sublimed in fine crystals. 
It has a strong pungent and ammoniacal smell, and ia 
(lecomi>osed by boiling water. The iodide also forms similar 
compounds with the monajnines. 

Tin-trieOiyl SuliiluUe, (G^HJoSnaSO^, is obtained by neutral- 
izing the oxide with sulphuric acid or decomposing the iodide 
with silver sulphate. It ia slightly soluble in water, and crys- 
tallizes from alcohol in glistening colourless prisms. This 
compound is also formed by the action of sulphur dioxido on 
tin-t«t methyl in presence of air. At the same time Tin-trietkyl 
ethyl sielphonate, (GjHJjSnSOjCjHj, is produced, and forms an 
oily liquid (Frank land and Lawranco). 

The nitrate ia obtained as a syrup by evaporating ita aqueous 
solution. Indistinct crystals may also be obtained. 

Tin-triethyl Cyanide, (CjH5)jSnCN, is obtained by warming 
the iodide with silver cyanide. It aublimea as a snow-white 
ninss,or crystallizes in thin uee<nes. It crystallizes &om alcohol 
in silky elastic prisms. 

Tin-triethyl Cyanate, (CjH5)jSnOCN, is obtained by warming 
the iotlide with silver cyanate in presence of alcohol. It 
crystallizes in thin prisma, and produces compound-ureas, with 
ammonia an<l the amines. That obtained by the action of 
ammonia, which yields a well crystallizable oxalate, has the 
composition, CO | gH,^^^^^^^^ 

Tin-triethyl Tkiocyanate, \C^^)^a^G:^, is formed by the 
decomposition of the iodide with silver thiocyanate, and crystal- 
lizes in colourk'sa prisms from alcohol. 

Tin-triethyl Hydrosulphidc, (CjHJjSnSH, ia produced by the 
action of sulphuretted hydrc^en on an alcoholic solution of 
the oxide, and it crystaUizes on evajjoration. If an equivalent 
quantity of the hydrate bo added to its solution, the 
formed, which is k'ft behind as an oily liquid on evapj 
tlie alcohol. 



le si^^ll^s 



ACETYL C0M1»0UNDS. 473 



^n addition to these, various other salts have been prepared. 

Hcthyl Sulphide, (C2H5)2SnS, is a whit« powder precipi- 

^y sulphuretted hydrogen from a solution of one of its 

'". is insoluble in dilute acids and ammonia, but dissolves 

»iig hydrochloric acid, caustic potash, and the sulphides 

iho alkali metals. In the dry state this body has a most 

disagreeable smell, resembling that of decomposing horse-radish. 

A peculiar compound having the composition (OjHJ^Snglj 

is formed amongst the products of the action of tin on ethyl 

iodide, and is obtained, according to Frankland, by treating tin- 

diethyl-dimethyl with iodine. It is a heavy oily liquid, having a 

strong smell resembling mustard- oil, and acting very injuriously 

on the lungs. Tliis compound requires further investigation. 

TlIALLIUM-DIETHYL COMPOUNDS. 

304 ^Vhen an ethereal solution of thallium trichloride acts on 
zinc-ethyl, thallium-diethyl chloride, (C2H5)2T1C1, is produced, 
and this crystallizes from hot water in glistening scales. A 
series of crystalline thallium-diethyl salts are obtained from 
this by double decomposition with silver salts. If the easily 
soluble sulphate be decomposed by caustic baryta, thallium- 
diethyl hydroride is obtained, crystallizing from hot water in 
fine silky glistening needles, having an alkaline reaction, and 
decomposing at 211** with explosive violence.^ 



ACETYL COMPOUNDS. 

305 Aldehyde or AcHaldehyde, C2H^G. In his memoir on oxide 
of manganese, published in 1774, Scheele mentions that if this 
oxide be placed in a closed flask, together with strong rectified 
spirit of wine and vitriolic or muriatic acid, and the mixture 
distilled at a moderate temperature, the alcohol which passes 
over possesses the smell of nitric ether. On the other hand, 
in his treatise on ether, published in 1782, Scheele states that 
if alcohol be distilled with sulphuric acid and black oxide of 
manganese, ether is first obtained, whilst ^Hn^tbe end of the 

' Hansen, Bcr. D^utsch. Ch^m, Gcs. iii. ; ^^^^^^^^fhem, Ph<irm, 
clxxvi. 257. 




474 THE ETHYL GROUP. 



operation acetic acid passes over. Other chemists made observa- 
tions of a similar character. Thus, Dabit, in the year 1800, 
recommended, for the preparation of ether, the addition of black 
oxide of manganese to a mixture of sulphuric acid and alcohoL 
He explained the formation of ether from alcohol by the 
removal of a part of the hydrogen and its oxidation to water, and 
not, as Fourcroy and Vauquelin had shortly before suggested, 
by the removal of the elements of water. In the same 
year the last-named chemists repeated Dabit's experiments,^ and 
found that the ethereal liquid thus produced is distinctly 
diflferent from common ether, possessing a smell resembling 
that of ordinary nitric ether. Their views with regard to tho 
relation of this body to alcohol are remarkable. "In this opera- 
tion," they say, " the alcohol does not lose any carbon but only 
a portion of its hydrogen, which combines with the oxygen of 
the black oxide of manganese." Hence they conclude that the 
liquid obtained in this way contains more carbon and oxygen 
and less hydrogen than alcohol. From their statements it is 
clear that the body which they examined was a mixture of 
several compounds. This product was, at the time, not further 
investigated, and it was not until 1828 that Dobereiner, studying 
the action of oxidizing agents upon alcohol, observed the occur- 
rence of a peculiar liquid to which he gave the name of oxygen- 
ether. This he prepared by the action of a mixture of alcohol 
and sulphuric acid upon either potassium chromate, potassium 
nianganate, or manganese dioxide. At tho same time Gay- 
Lussac stated that the body possessing the peculiar suffocating 
odour which had before been noticed was a mixture of alcohol, 
ether, and oil of wine. In the following year Dobereiner ex- 
pressed the opinion that in tho oxidation of alcohol two 
substances are formed, a heavy and a light oxygen-ether, the 
latter differing from common ether, as he had found in 182J^, 
not only by its peculiar smell, but also inasmuch as it is converted 
into a resin when heated with potash. He also showed that a 
liquid possessing similar properties may be obtained by tho 
action of platinum bhick on alcohol. Various chemists now 
investigated this subject without coming to a satisfactory con- 
clusion. They, however, proved that the heavy oxygen-ether, 
obtained by the action of sulphuric acid and manganese 
dioxide, mainly consists of oil of wine. The boily obtjiined by 
tho action of ])latinum black was found to contain a compound to 

* S'.ir IVtluT |nv|>jiiv k la inaniert' ilu ritoym l)al»it, Jmi. dc Chi/niCf xxziv. 818« 



ACKTALDKTIYDE. 476 



which Liebig gave the name of acetal (to be hereafter described). 
In addition, however, to acetal, the product contains a still more 
volatile liquid possessing a pungent smell, and this is the cause 
of the production of the brown resinous mass formed by the 
action of caustic potash. Liebig then pointed out the peculiar 
power of reducing silver salts which this substance possesses, and 
Dobereiner observed that this same body is produced by the 
action of nitric acid upon alcohol, thus accounting for the 
fact that it always occurs in crude so-called nitric ether (ethyl 
nitrite). He next showed that the body thus obtained possesses 
the power of forming a crystalline compound with ammonia, 
and three grains of this compound were sent by its discoverer 
to Liebig, and it was the examination of this preparation 
which led to the true explanation of this somewhat compli- 
cated subject. Liebig proved that in the first act of oxidation 
alcohol loses two atoms of hydrogen, as Dobereiner had sup- 
posed, giving rise to the above-mentioned volatile liquid, for 
which he proposed the name of alcolwl - dehydroyenatum or 
aldehyde} 

Aldehyde is not only formed by the action of various 
oxidizing agents, such as chlorine, upon alcohol, ether, and 
other ethyl compounds, but is also produced when the vapours 
of these bodies are passed through a red-hot tube, a variety 
of other compounds being formed at the same time. 

306 Preparation, — Liebig gives the following directions for the 
preparation of aldehyde : A mixture of 4 parts of 80 per cent, 
spirit, 6 of manganese dioxide, 6 of sulphuric acid, and 4 of 
water is distilled. When gently warmed the mixture begins 
to froth slightly, and the aldehyde, together with alcohol and a 
few other products, passes over. The process is interrupted as 
soon as the distillate begins to redden litmus, which is usually 
the case when 6 parts of liquid are contained in the receiver. 
The distillate, consisting of aldehyde, alcohol, &c., is mixed with 
an equal weight of calcium chloride and again distilled, the 
receiver being kept very cold. After 3 parts have passed over 
the distillate is again rectified with an equal weight of calcium 
chloride until \\ parts have passed over. This last portion 
is anhydrous, but the aldehyde contains alcohol and certain 
compound ethers. For the purpose of purification one volume 
of this liquid is mixed with two volumes of ether, the mixture 
surrounded by cold water, and dry ammonia gas passed in to 

* Ann, Pharm. xiv. 133 ; xxii. 273. 



476 THE ETHYL GROUP. 




saturation. The gas is rapidly absorbed with great evolution of 
heat, and crystals of aldehyde-ammonia separate out. These 
crystals are washed three times with absolute ether and dried. 

The preparation of the aldehyde from this compound is very 
easy. The aldehyde-ammonia is dissolved in its own weight of 
water, the solution brought into a retort, and 3 parts of sulphuric 
acid previously mixed with 4 parts of water added. On 
gently warming this in the water-bath the aldehyde is evolved 
with frothing. The distillation is stopped as soon as the water 
in the water-bath begins to boil. The hydrated aldehyde which 
passes over is then dried by rectification over an equal bulk of 
calcium cliloride in coarse lumps. Heat enough is evolved by 
the combination of the calcium chloride with the water to raise 
the liquid to the boiling-point, so that good condensation is 
required from the very beginning. The distillate thus obtained 
is mixed with pounded chloride of calcium and again distilled 
from a lukewarm water-bath at a heat not exceeding 30**. 

Stadeler ' recommends the use of potassium dichromate in 
place of manganese for the oxidation. Fifteen parts of this salt 
are brought into a large retort standing in a freezing mixture 
and connected with a spiral condensing-tube surrounded with 
water having a temperature of 50^ A cold mixture of 10 parts 
of alcohol and 20 parts of sulphuric acid, previously diluted with 
three times its volume of water, is then poured on to the broken 
pieces of dichromate, the freezing mixture removed, and the 
vapours of aldehyde which come off condensed in the cylinders 
(', c, Fig. 95, partly filled with ether and surrounded by a freez- 
ing mixture. At the end of the operation the retort requires 
to be slightly warmed. The ethereal solution is then treated 
with ammonia in the way already described, and the aldehyde 
regained from the aldehyde-ammonia, which has the empirical 
formula Cgll^O.NIIj, by the above-mentioned method.* 

Aldehyde is obtained on the large scale as a by-product in the 
manufacture of spirit, where it comes over with the first runnings 
(see p. 294), and may be obtained perfectly pure by the use 
of a rectifying column.* 

It may also be cheaply obtained and in quantity by the action 
of ozonizeil air upon alcohol, and is likewise formed by the dry 
distillation of a mixture of the calcium salts of acetic and formic 
acids : 

* Joitrn. Pral'i. Chnn. Ixxvi. r»4. 
^ lltnniDW, /Ciifir. Chfm. Intl. ii. 27r». 



PBOPEBTIES OF ALDEHYDE. 



L 



H 

I 
CO 

I 
OH 



CH„ 
I 
C^O 

[ 

H 



307 Properties. — Acetaldehyde ia a colourless, easily mobilo 
liquid, boiling at 20°8, and having at 0° a specific gravity of 0*8009 
(Kopp). Its vapour density was found hy Liebig to be 1'532. 
It baa a peculiar ethereal suffocating odour, and its vapour, 
when inhnled in large quantity, produces a cramp, wbich for 




Fio. 95. 

a few seconds takes away the power of respiration (Liebig). It 
is miscible with water in all proportions, heat being evolved, 
and it ia likewise soluble in botli alcohol and ether. The 
addition of water raises the boiling-point of aldehyde. Thus, 
a mixture of one part of aldehyde and three parts of water 
boils at 37°. It is, however, separated from its aqueous solution 
by the addition of calcium chloride. Aldehyde likewise dissolves 
sulphur, phosphorus, and iodine, the liiat with a brown colour, 
and it is easily infiaminable, burning with a luminous flame. 



47JJ THE miYL GROCP. 




Like all aldehydes (see page 172), acetallehyde readily under- 
goes change. It absorbs atmospheric oxygen, and is slowly 
converted into acetic acid Oxidizing substances bring about 
this change more quickly. When warmed with an ammoniacal 
srjlution of silver nitrate, silver separates out as a minor-like 
deposit which adheres firmly to the glass : 

C^,0 + Ag,0 = 2 Ag + C^,0^ 

This serves for the detection of the smallest trace either of 
aldehyde or of silver. When the solution contains one part 
of silver nitrate to 1,000 of water a brilliant mirror is formed, 
with 2,000 of water, the mirror-like deposit is only partial, and 
the solution becomes violet coloured, owing to the presence of 
finely-divided silver. When the solution is still more dilute, no 
depcisit of silver is obtained, the violet tint alone being observed. 
This can be noticed when one part of nitrate solution is diluted 
with 4,000 of water, such a liquid producing only the slightest 
opalescence ^ on admixture with a chloride. 

It was formerly supposed that when aldehyde acts upon silver 
oxide, or when alcohol is oxidized by platinum black, a com- 
pound was formed intermediate between aldehyde and acetic 
acid. To this the name of acetous, aldehydic, or lampic acid 
was given. Hcintz and Wislicenus proved that this body is 
a mixture of acetic acid and aldehyde.^ 

Under certain circumstances aldehyde combines with nascent 
hydrogen to form ethyl alcohol This reduction is not brought 
about by zinc and hydrochloric acid, whereas sodium amalgam, 
in presence of water, as well as in presence of dilute acids, 
does eflfect this change.' Alcohol is also produced when aldehyde 
is heated with zinc and ammonia at 30'' to 40'' under a slight 
increase of pressure.* 

When chlorine acts upon aldehyde, acetyl chloritle, as well as 
various other products which will be afterwards tlesc*ribed, are 
firmed, acconling to the duration and other conditions of the 
experiment.* 

According to the theory of types, aldehyde is coiisiiKrod as 

OHO) 
etyl hydride, * \t !' • T^^^^^ view is in accordance with 

» W. and H. Ilo««'rH, Journ. Prakt, Chrm. xl. 240. 
' ^'"U'J- "^W' cviii. 101. 

• Wurtz, i'lu/iftt, HfH'i, liv. 915; Ann, Chem. Pharm, cxxiii. 140. 

• Ij«»riii, Com}*t. Ji' iuL Ivi. 845 ; Ann. Chcm, Phann. cxxviii. 3o5, 884. 

• Wurtz. Ann. Chim, Phin. [3], xiix. 58; />«//. So,'. Chim [2], x\y. 08; 
£rr, Dfufsih. rhfm, (h^, iii. 790. 



ace 



POLYMERIZATION OF ALDEHYDE. 479 

its formation from acetic acid, as well as with the action of 
chlorine upon it. In many other reactions, however, it behaves 
as the oxide of the dyad radical ethidene. Thus, phosphorus 
pentachloride converts it into ethidene dichloride or dichlor- 
ethane, CH3.CHCI2. These compoimds, as well as others which 
it forms with ammonia and with the acid sulphites of the alkali 
metals and other bodies, will be described under the ethidene 
compounds. 

Aldehyde is used in the arts for the manufacture of aldehyde 
green, one of the so-called aniline colours. 

308 Polymerization of Aldehyde. — Small quantities of weak 
reagents convert aldehyde into polymeric modifications. Of 
these a large number were formerly supposed to exist. A more 
accurate examination has reduced this number to two. 

Paraldehyde, CgHjgOg, was first obtained by Fehling, and 
described as elaldehyde.^ It is easily formed by the action of 
small quantities of mineral acids, zinc chloride, or carbonyl 
chloride on aldehyde. It is best obtained by adding a few drops 
of concentrated sulphuric acid to aldehyde, evolution of heat 
and contraction taking place. On cooling the liquid to 0*", 
paraldehyde crystallizes in large prisms which melt at l(f'b. 
The liquid boils at 124°, and at 15° has a specific gravity of 
998. A determination of its vapour density gives the number 
4*583,^ which agrees with the above molecular formula; the 
constitution of paraldehyde is, therefore, probably represented 
by the following formula : 

CH3 



i 



H 

\ 
O 



CHq CH CH CHq. 

\/ 



It is slightly soluble in water, dissolving more readily in 
cold than in hot water. Phosphorus trichloride converts it 
into dichlorethane, being first split up into three molecules of 
acetaldehyde. This decomposition also takes place when its 
vapour is heated, or when it is distilled in contact with a body 

* Ann. Chem. Pharm. xxvit 319. 

2 Weidenbusch, Ann. Chem. Phnnn. Ixvi. 152. 



480 THE ETHYL GROUP. 



in presence of which it has been formed, as, for instance, with 
sulphuric acid. 

The behaviour of paraldehyde towards carbonyl chloride is 
remarkable. A mixture of these two bodies is extremely diffi- 
cult to separate, boiling pretty constantly about 45'. Hamitz- 
Hamitzky, who first examined the substance, believed it to be a 
definite compound and termed it chloracctene, giving to it the 
formula CgHjCl, and remarking that it decomposes into aldehyde 
and hydrochloric acid. This fact was afterwards confirmed by 
Friedel, who showed that on standing it decomposes gradually. 

The existence of a compound isomeric with chlorethylene, 
possessing such singular properties, could not be theoretically 
accounted for, and this gave rise to many hypotheses, until 
Kekul6 and Zincke proved that " the most remarkable pro- 
perty of this body is its non-existence." ^ They, noticed that 
carbonyl chloride acts as a kind of ferment on aldehyde, 
small traces being able to convert a large quantity into par- 
aldehyde, heat being evolved. If, however, this latter sub- 
stance remain for any length of time in contact with carbonyl 
chloride it is partly re-converted into aldehyde without evolution 
of heat. The substance obtained by the action of aldehyde 
or paraldehyde on carbonyl chloride is, therefore, a mixture of 
the two modifications of aldehyde, the proportion between 
these being dependent on the temperature and the quantity of 
the ferment. If this mixture be gontly warmed, aldehyde and 
carbonyl chloride pass over first; the distillate becomes warm 
by the renewed formation of paraldehyde, but on quickly 
shaking the compound with lead oxide, pure aldehyde is first 
obtained, and afterwards pure paraldehyde. Hydrochloric acid 
acts similarly to carbonyl chloride, but, as it appears, still more 
energetically.* 

309 Metaldeliydc. The formation of this substance was first 
obser\'ed by Liebig, who found that needle-shaped crj'stals are 
occasionally deposited from aldehy<le, and that these possess a 
composition identical with the original substance.* This com- 
pound was then further investigated by Fehling,* Weidenbusch,* 
and Kekuli5 and Zincke.^ It is formed together with paralde- 
hyde by the action of acids, carbonyl chloride, .&c., on aldehyde, 

* Bfr. J>uisch. Chem, OcJi, iii. 136 ; Chrm. Soc, Jnurn. xxv. 401. 

' Ann, Chem. Pharm. clxii. 125. • w//ri. Phnrm. xiv. 141 ; xxv. 17. 

♦ fb. xxvii. 310. » lb. Ixvi. i:.2. 
^ lb, clxii. 145. 



METALDEHYDE. 481 



cooled in a freezing mixture. It is likewise produced when 
aldehyde is allowed to remain in contact with calcium chloride 
or zinc chloride at ordinary temperatures. Moreover, it is some- 
times formed, under unknown conditions, when aldehyde is 
allowed to stand by itself. 

Metaldehyde separates out in needles, or in clear colourless 
quadratic prisms, which sublime at 100**, without previous 
fusion. When heated to 112'' to 115°, in a closed tube, metalde- 
hyde passes into ordinary aldehyde, and for this reason it has not 
been possible to determine its vapour-density, or its molecular 
weight. On heating with carbonyl chloride, sulphuric acid, &c., 
it yields aldehyde, and it behaves like the mono-molecular 
compound towards phosphorus pentachloride. 

Aldehyde-Besin is formed by the action of aqueous or alcoholic 
potash on aldehyde, when the liquid first becomes yellow, next 
brown, and then solidifies to a reddish-brown resinous mass, the 
composition of which has not been ascertained. At the same 
time formic acid and acetic acid are formed, together with a 
very volatile, strongly-smelling compound, which, when well- 
cooled, condenses to an oily liquid. This quickly absorbs 
oxygen, and is converted into a golden-yellow, thick liquid, 
smelling of cinnamon, which quickly becomes resinous (Weiden- 
busch). This same resin is also formed when alcoholic solution 
of potash is allowed to remain in contact with the air. The 
colour as well as th^ smell which alkalis produce with aldehyde 
are so characteristic that the latter compound may be easily 
detected by this means when mixed with other bodies. 

When the vapour of aldehyde is passed over heated caustic 
potash or soda-lime the following reaction takes place : ^ 

CgH.O + KOH = C2H3KO2 -h Hg. 

310 Farathialdehyde, CgHigSg. By passing sulphuretted 
hydrogen into an aqueous solution of aldehyde, Weidenbusch 
obtained a colourless oily liquid, which, when treated with small 
quantities of sulphuric or hydrochloric acid, is converted into 
a white crystalline mass, to which he gave the name of acetyl 
mercaptan.2 This liquid was afterwards termed sulphaldehyde. 
Hofmann then showed that it possesses the above molecular 
formula, as its vapour density is 6°'29,* and Klinger proved that 

* Damns and Stas, Anii. Chim. Phya. [2], Ixxiii. 115; Ann. Chem, Pharm, 
xxxw. 161. 

* Atm» Cktm. Phann. Ixvi. 158. » Bcr, DeuUcIi. Chan, Ges. iii. 588. 

] I 




482 THE ETHYL GROUP. 



tlic coinpouiid obtained in the above manner is a mixture of two 
i«oineric modifications.* 

a'Parathialilchyde is obtained by repeated crystallization uf 
tluj above compound from alcohol, or by passing sulphuretted 
hydro^'en into a dilute acidified solution of aldehyde ia alcohol, 
wlieu other bodies are formed at the same time. These can be 
Boparated by repeated crystallization. To the above-mentioned 
licpiid thiiddehyde, Klinger gave the probable fonnula, C^HgS^. 
This, when suspended in water and treated for some time with 
sulphuretted hydrogen, passes into another oily body, which 
apparently has the composition 4C^H„S2 + HoS, and does not 
andergo change in i)rcsence of hydrochloric acid. If, however, 
some aldehyde be added to this, it quickly solidifies, and the 
solid mass consists mainly of a-parathialdehyde. This crys- 
tallizes from alcoliol in long white prisms, or from concentrated 
solution in thin tables. These melt at 101°, and the liquid 
boils at 24G' — 247°. It foniis with silver nitrate two com- 
pounds ; one, C^jH^^Sj 4- AgNOg, forms white opaque needles 
concentrically grouped, the other, CgH,.^S3 -f SAgNOj, crystal- 
lizes in microscopic prisms. A warm solution of common salt 
separates the thialdehyde from both of these. 

^-Parathialdchi/de is formed from the foregoing compound 
by warming it with acetyl chloride, and also by dissolving it 
in cold sulphuric acid and adding water. It crystallizes from 
solution in glacial acetic acid in long glistening needles which 
melt at 124° — 125"*, the liquid boiling with slight decomposition 
at 245° — 248°. The determination of its vapour density gave 
the number GO, which is rather lower than that required by 
theory. With silver nitrate this btxly also yields two compounds, 
viz., C^jHj2S3 4- AgNOg, crystallizing in compact colourless 
needles, and C'^jUj.^S3 + SAgNO^, in tine scales possessing a 
j>early lustre. 

The cause of the isomerism of the above thialdehvdes has 
not vet been established. It is ]>osj?ible that thev have a 
different chemical constitution, but it is more probable that 
their difference is due to physical isomerism. 

* JJ',: Deutsche Ch/n/i. Gcs. x. liJU3 ; xi. I«r2;j. 



HISTORY OF ACETIC ACID. 483 



ACETIC ACID, CjH^Og. 

311 It has already been mentioned that the only acid with 
which the ancients were acquainted was vinegar, and that the idea 
of acidity was expressed by a closely related word. The eflferves- 
cence produced by vinegar when poured on certain substances 
was also noticed in very early times, and is mentioned in the 
Proverbs of Solomon,* whilst the solvent action of vinegar on 
many bodies had also attracted attention. Thus Pliny says, 
concerning the properties of vinegar, " Aceto summa vis est in 
refiigerando, non tamen minor in discutiendo ; ita fit ut infusum 
terrae spumet.'* 

The ancients held exaggerated views respecting the solvent 
power possessed by vinegar. This is shown by the well-known 
story, related by both Livy and Plutarch, of Hannibal dissolving 
the Alps by means of vinegar, whilst Vitruvius states that 
silicious rocks, which can be neither attacked by the chisel nor 
by fire, are dissolved when heated and then moistened with 
vinegar. 

The vinegar of the ancients was of course an impure wine- 
vinegar, and it is to the alchemists that we owe the first pro- 
duction of pure acetic acid by distillation. Geber, in his treatise 
De Investijatione Magisterii, writes : "Aceti acerrimi, cujuscunque 
genera, subtiliantur et depurantur, et illorum virtus sive effectus 
per destillationem melioratur." Basil Valentine apjiears to have 
been acquainted w-ith the preparation of strong but impure 
acetic acid, obtained by the distillation of verdigris (which he 
termed a vitriol), for he says : " Take the proper oleum vitrioli 
made out of the vitriol of verdigris." But on the other hand, 
the alchemists often used the name of philosophical vinegar 
for oil of vitriol. 

Acetic acid obtained from verdigris was afterwards termed 
spiritus veneris or acctum radicale. Stahl in 1697 described 
better methods for obtaining strong acetic acid. Thus, he 
allowed weak vinegar to freeze, and poured off the acid, which 
remained liquid, from the solid mass which separated out. In 
his Specimen Bechcrianum, published in 1702, Stahl describes 
the neutralization of the vinegar with alkali, the evaporation 

* Sec vol. ii. part. i. p. 32. 

I I 2 



484 THE ETHYL GKOUP. 



of the solution, and the distillation of the solid salt with 
sulphuric acid. He states in another work, published in 1723, 
that acetic acid may be obtained in a similar way from sugar 
of lead by the action of oil of vitriol. He also mentions that 
the strong acid is inflammable, a fact which had not been 
recognised up to that time, as it had been supposed that acetic 
acid differed from alcohol, especially in not being inflammable 
Yon Lauraguais made the same observation in 1759, and he 
also noticed that concentrated aculum radicale could be 
obtained in the crystalline state, a fact soon afterwards con- 
firmed by other observers. So that Durande, in editing 
Morveau's Handbook of Chemistry in 1777, terms the solid acid 
vinaigre glacial, a name still used. In 1772 Westendorf sug- 
gested the use of acetate of soda instead of the potash salt for 
the preparation of the acid, and Lowitz in 1789 discovered that 
aqueous acetic acid may be so far concentrated by frequent 
rectification over powdered charcoal as to crystallize when 
cooled, and to this substance he gave the name of ice-like 
acetic acid. 

31a The production of acetic acid by the dry distillation of 
wood or other vegetable fibre must have been known in early 
times ; thus Glauber speaks of it in his Fumi Novi PhUosophvci^ 
published in 1648, in a way which shows that wood-vinegar 
was a well-known substance at that time. He says that its 
properties do not differ greatly from those of common vinegar, 
for which reason he teimed it a^^etum lignorum, and states that 
by rectification it may be made as good as acctxtm vini} Boyle 
is even more precise in his identification of pyroligneous with 
ordinary acetic acid, for he says, "Also guiacum and divers 
other woods, that do not at all taste sour, will, being distilled 
in retorts, afford spirits, that are furnished with store of 
acid particles, which as I have tried will hiss upon alkalies, and 
will dissolve coral, and even lead itself calcined to minium 
and make sacchancm satumi of it." 

In his Elementa Chemiae, published in 1732. Boerhaave states 
that acida acetosa is formed by the action of heat on vegetable 
substances. This expression points to the conclusion that in 
former days the existence of a variety of different kinds of 
acetic acid was assumed. Indeed every organic acid was looked 
upon as a mollification of acetic acid. Thus, the plants now 
known to contain oxalic acid are still termed acdosffy acetosellf, 

> Glaul>er, Op. {vd, ltf59) p. 31. 



HISTORY OF ACETIC ACID. 486 



&c. Even when formic acid was discovered, it also was believed 
to be a modification of acetic acid. It therefore appears not 
unnatural that a distinction should have been drawn between 
acetic acid and pyroligneous acid, and it was not until the 
year 1800 that Fourcroy and Vauquelin proved that the acid 
obtained by the dry distillation of wood, as well as of sugar, 
gum, &c., is simply acetic acid mixed with a small quantity of 
an empyreumatio oil. 

When animal substances undergo dry distillation acetic acid 
is also formed. The substance thus obtained was, however, 
considered by Berthollet in 1708 to be a peculiar substance 
to which he gave the name of acide zoonique. But Th^nard 
showed in 1802 that this substance is identical with ordinary 
acetic acid, as well as with the acid obtained by the destructive 
distillation of wood. 

313 The early views concerning the formation of acetic acid 
from alcohol are but vague. They agree in considering that no 
addition is made to the alcoholic liquid in its conversion into 
acetic acid, the change consisting essentially of a decomposition 
of the constituents of the alcohol, but not of a combination of 
them with another body. Thus, Basil Valentine says that the 
materials placed in the fermenting vat have assumed another 
property, being no longer wine, having been transmuted into 
vinegar by putrefaction.^ It was later assumed that vinegar 
was formed by the combination of alcohol with saline particles, 
such, for instance, as those of cream of tartar. For example, 
Lemery says : " The spirit of vinegar consists in an acid ; essen- 
tial or tartareous salt is very different from spirit of wine ;'* ^ and 
Macquer in 1778, in his Dictionary/ of Chemistry, says that 
it is not possible to form any definite idea of the changes which 
take place in the acetic fermentation, though it appears as 
if an intimate combination of the acid constituents with the 
combustible constituents of the wine takes place. 

Priestley having proved that common muriatic acid is an 
aqueous solution of " a marine acid air," and hydrofluoric acid 
a solution of " fluor acid air," he, for a short time, looked upon 
acetic acid as containing '* a vegetable acid air," but soon found 
that no such thing could be obtained from it.^ 

We owe to Lavoisier the first proof that acetic acid is a 
product of the oxidation of alcohol. He observed that when 

* Ed. PetraeuSf p. 61 . ^ Keiirs transl. p. 577. 

' Obaervatioiifi on different kinds of Air, iii. 403. 



48C THE ETHYL GROUP. 



wine exposed to the action of the air is converted into vinegar 
its volume becomes smaller. He showed, moreover, that wine 
is converted into vinegar by other oxidizing agents. 

The composition of acetic acid was accurately determined by 
Berzelius in 1814, and Saussure having at the same time ascer- 
tained the composition of alcohol, it now became possible to 
explain the mode in which the latter was converted into the 
former substance. It was, however, at this time supposed 
that a large quantity of carbonic acid escapes during the 
process, and it was not until 1822 that Dobereiner showed that 
in the oxidation of alcohol only acetic acid and water are 
formed. And it is to him that we owe the true explanation, for he 
determined the quantity of oxygen which is needed to produce 
the change.^ 

314 Acetic acid occurs widely distributed in nature, portly in 
the free state and partly in the form of salts and ethers. According 
to Yauqueliuy Hermstadt, and others, it is contained in the 
juices of many plants, and especially of trees, either free or 
combined as potassium or calcium acetate. It also occurs, 
together with other volatile acids, in water which has been 
distilled from odoriferous flowers or from aromatic acids and other 
vegetable substances. As triacetin, 0311^(0211302)3, it is found 
as an oil in the fruit of the spindle-tree, Ero7iymus europaeus, 
and in the oil of the seeds of Crotan tiylium, whilst the liquid 
oil from the seeds of Hcradcum gignnteum and H, sjH)ndyleum 
contain octyl acetate, OgHj-.02H302, whilst sycoceryl acetate, 
OigHgg. O2H3O2, is found in the resin of the Ficus rvhiginosa. 
Various animal liquids also contain small quantities of acetic 
acid, and it is likewise found in other products of fermentation 
and putrefaction of organic bodies, as well as formed by their 
dry distillation. It is, moreover, a product of a large number of 
oxidizing processes, and, as it does not undergo change, even in 
the presence of powerful oxidizing agents, it is often the final 
product of the complete oxidation of compounds which contain 
one or more methyl groups. Many carbon compounds which 
do not contain the methyl group, also yield this acid when 
heated with alkalis, for the alkali not only acts as an oxidizing 
but also as a hydrogenating agent. 

315 SyntheMA of Acetic Acid. — It has already been stated that 
acetic ncid can In? built up from its elements (see p:ige 179). 
Of the diffiTent synthetic* methoils, that bv ini'iins of trichlur- 

» Schireig. Journ, liv. 410. 



SYNTHESIS OF ACETIC ACID. 487 

acetic acid claims our attentioD, as having been discovered the 
fu^st. 

Trichloracetic acid was first prepared by Dumas in 1830, b; 
actiug on acetic acid with chlorine. In 1S43 Kolbe found that 
when carbon disulphide is treated with chlorine at a red-heat, 
carbon tetrachloride, CCI4, is formed. And two years later he dis- 
covered that the vapour of this compound, when passed through 
a red-hot tube, is converted into chlorine and tetrachlorethjlene, 
CCl^. Chlorine in the sunlight acts upon this latter body in 
presence of water, giving rise to trichloracetic acid, inasmuch 
as hexchlorethane is formed, and this in the nascent condition is 
decomposed as follows : 

CCI3.CCI3 + 2 HjO = CCij.CO.OH + 3 HCI. 

Now shortly before this, Melsens had observed that trichlor- 
acetic acid in aqueous solution is converted into acetic acid in 
presence of potassium amalgam, and thus the problem! of the 
synthetic production of acetic acid was satisfactorily solved. 

316 Manufacture of Vinegar. — All oxidizing agents convert 
alcohol iirst into aldehyde and then into acetic acid. Ozone 
readily effects this change, as does pure oxygen or air in presence 
of platinum black. In absence of this latter substance neither 
strong nor dilute alcohol can be thus oxidized. On the other 
hand, fermented liquors, when exposed to air, soon become 
sour. This depends upon the fact that they contaiu nitrogenous 
compounds which are able to act as carriers of atmospheric 
oxygen. This, however, they can only do when the percentile 
of alcohol present does not rise above a certain limit. It is 
for this reason that strong wine, such as port or sherry, does 
not become sour on exposure to air. 

Various processes are adopted for the manufacture of vinegar, 
and the product, according to its mode of preparation, goes by 
various names. 

Wine Vhiegar is prepared in large quantities in wine-growing 
countries, and especially near Orleans, from the poorer quali- 
ties of wine. The manufacture is carried on in the open 
air, or in buildings termed vijiaigrerUs, which always have a 
southern a.spect. The vinegar casks, called mothtra, hold from 
50 to 100 gallons, and a number of these casks are j" 
rows. The process is often carried on in the open air^^ 
from 8 to 20 such rows form what is termed a 
Two holes are bored on the top of the front end of ■ 




488 THE ETUYL GROUP. 



for the purpose of charging, ami also for allowing firee access 
of air. 

In commencing the operation, these casks are one-third filled 
with the strongest vinegar, boiling hot, and to this, the charges 
of wine, 2^ gallons to each cask, are added at intervals of eight 
days. When the casks are more than half filled, one-third of 
the contents of each " mother " is syphoned off, and this opera- 
tion repeated as long as desired. The temperature of the whole 
sljould be kept from 24"* to 2T C. Wine vinegar always con- 
tains acetic ether, as well as the other ethereal salts contained in 
wine, and these give to it the fragrant smell and taste for which 
it is valued. The wine prepared from other fruit as well as 
grapes is sometimes also used for the manufacture of vinegar. 
For the explanation of the changes which here take place the 
chapter on fermentation must be consulted. 

Malt Vinegar is largely manufactured in England. In this 
j)rocess the wort is allowed to ferment and the fermented liquor 
brought into ciisks placed on their sides with the bung-holes 
open, an additional circulation of air being kept up by means 
of an orifice bored at each end of the cask near its upper 



edge. 



317 Qnivk Viiufjar Process. — After it had leen proved that 
acetic acid is an oxidation product of alcohol, the manufacture of 
vinegar by a (^uick process was introduced in 1823 bySchutzen- 
bach. The vinegar generator, technically called a graduator, is 
a large tun of oak (Fig. 06), frequently 13 feet high, 15 feet 
wide at the bottom and 14 feet wide at the top. A horizontal 
I>erforated shelf is fjistened in the tub, 18 inches from the 
bottom, and two inches above this eight or ten holes are 
bored in the side of the tub and inclining downward from 
the outside. A similar disc is placed one foot from the top of the 
tub; with the holes 1 inch apart and \ inch in diameter. These 
holes are loosely filled with cotton-wick or ]>ack-thread, a knot 
being made at the top to prevent them falling through. Be- 
tween these shelves the interior of the tun is filled with deal 
shavings, which have been well washed and afterwanls stove- 
dried. Charcoal is sometimes used. The whole being arrange<i, 
strong vinegar hoateil to 20° — 25° is poured into the graduator 
and allowed to stand for one or two days, and after this weak 
spirit containing 5 — 7 per cent, of alcohol is introduced, .<»ome 
fermented malt- liquor being also added. This then runs 
through tlu» shavings and comes in contact with a large quantity 



MANUFACTURE OF VINEGAR. 480 

uf air, when oxidation occurs, and consequently evolution of heat 
takes place and the circulation of air becoraeB rapid. The fresh 
air cornea in through the lower holes, and having lost some of 
its oxygen passes out through the upper ones. The graduator, to 
begin with, acta but slowly, and it ia only after some time that a 
quick action commences. Tbia depends upon the fact that tbe 
acetification is due to tbe shavings becoming gradually covered 
with a microscopic organism (Hfi/codeniia ajxti), or, as it is some- 
times called, "mother-of-vinegar." It has been shown by Pasteur 




Fio, PB. 

that the formation of vinegar is due to the growth of this oi^an- 
ism, which plays the part of a carrier of atmospheric oxygen, and 
according to the observations of this distinguished chemist the 
rapidity of the process may be greatly increased by the addition 
of a small quantity of the mycoderm at the beginning of the 
operation. The constant presence of alcohol is, however, neces- 
sary, as in its absence the acetic arid is burnt by the ferment 
into carbon dioxide a:ul water. Weak alcohol is oxidized more 



490 THE ETHYL GROUP. 



quickly than strong. When very strong acetic acid is needed, 
the mixture has to be passed througli three tubs and a fresh 
quantity of alcohol added, and sometimes submitted to a fourth 
tub in order to obtain an acid of the requisite strength. 

As the successful working of the graduator is greatly depen- 
dent on the temperature, which must range between 36"* and 40', 
a thermometer is always employed, and it is moreover necessary 
to ascertain that the flow of the liquor is regular, and that it is 
properly diffused over the chips. The amount of air wliich is 
allowed to have access must also be regidated. If this is insuffi- 
cient a loss takes place, inasmuch as a considerable quantity of 
volatile aldehyde is formed, the smell of this compound being 
almost always recognisable in the vinegar-house. If, on the other 
hand, too much air be allowed to pass through the graduator a 
loss takes place through the volatilization of alcohol vajwurs. 
To regulate the supply of air it is not uncommon to join the 
top of the graduator with a flue and damper connected with 
a chimney. 

According to theory, each percentage- volume of alcohol should 
yield a vinegar containing one per cent, by weight of acetic acid, 
but, owing to unavoidable loss, these proportions are not attained 
in practice. In addition to this, a portion of the alcohol does 
not undergo oxidation, and this is larger as tlie strength of the 
vinegar increases ; and thus the strongest vinegar which can be 
prepared in this way, rising up to 10 to 15 per cent, of acetic 
acid, usually contains several tt-nths per cent, of alcohol. In 
good working, 100 liters of any given percentage of alcohol by 
volume will yield 84 kilos, of vinegar containing the given per- 
centage of acetic acid by weight ; but the process is often 
attended with a loss of 20 per cent., as it is difficult to keep 
the summer temperature exactly at the requisite point, and 
when the ferment becomes hot the oxidation takes place at an 
extremely rapid r.ate. ^ In many vinegar-works the vinegar fly 
(^DrofiophUa cr/laris) occurs in enormous numbers. The larvoe of 
this tly live in fermenting liquors, especially in those undergoing 
the acetous fermentation, and are also found in decaying fungi 
and rotten fruit The vinegar eel {Anquillula acefi) is also 
frcciucntly found in the vats, and is often from 1 to 2 mm. in 
length. It was forme riy supposed to bo an infusoria, but is now 
reco;?nised as belonging to the Xrmnfotfra. 

Spirit vinegar is colourless. TIm* vinegar for table use is 

* Kr:inior» Hfr. Ent^r. ('hf,ti. Imi. ii. 3P9. 



PREPAHATION OF PURE ACETIC ACID. 491 

oftou coloured yellow by bumt-sugar, and not uiifrequcDtly 
cream of tartar and acetic etlier are added to give it the flavour 
of wine-vinegar. Tlie adulteration of vinegar with sulphuric 
acid is not infrequent, the law permitting an addition of O'l per 
cent, of this latter acid, as it was believed that by this means the 
vinegar was rendered more stable, although this is an error. 
In order to detect the presence of free sulphuric acid in vinegar, 
a piece of filter-paper is wetted with the vinegar under exami- 
nation and dried, or the acid is evaporated with a small quantity 
of sugar. In either case carbonization occurs if free sulphuric 
acid be present. Free mineral acids may also be detected by 
boiling 100 grams of the vinegar with about 50 milligrams of 
starch for about thirty minutes. If mineral acids are present 
tlie starch is converted into dextrin and starch-sugar, neither of 
which are turned blue by iodine. 

318 Preparation of Concentrated Acetic Acid. — la addition to 
its uses for the table, vinegar is employed for the preparation 
of various acetates, and these again for the preparation of 
strong acetic acid. This is, however, obtained in larger 
quantity from pyroligneous acid, which is neutralized with 
lime and thus separated from wood-spirit and acetone, and the 
residue evaporated to dryness. In tijis way a crude calcium 
acetate is obtained which has a brown or black colour and yields, 
on distillation with hydrochloric acid, noetic acid, possessing a 
strong empyreumatic odour, largely used for many purposes in 
the arts. In order to obtain a pure acid from this source the crude 
brown or black calcium salt is heated in a drying furnace to a 
temperature of about 232" to carbonize the resins and other 
impurities. The mass thus obtained is termed white or grey 
acetate. Another process, proposed by Voickel,^ accomplishes this 
end more completely. Tlie solution of the crude salt when about 
half evaporated is treated with hydrochloric acid until a weak 
acid reaction is observed, when a large quantity of tar as well as 
of carbolic acid, creosote, and other bodies, separates out The 
clear solution yields, on evaporation, a brownish coloured residue, 
which can then be ignited for further purification. By distilla- 
tion with the requisite quantity of hydrochloric arid, acrtlc acid 
containing from 40 to 50 per cent, of the pure acid 1 "*^~ 
obtained. When this has a tarry smell or contiias aat^ 
hydrochloric acid, it may be purified by distillation over a 
■{uaiitity of potns.^ium dichromate or potassium pot 
> Ann. Chem. J^rm. IxixiL 19. 




492 THE ETHYL GROUP. 



\ 



When chloride of calcium is added to a solution of calcium 
acetate and the whole concentrated, crystals of calcium chlor- 
acetate, Ca(C2U302)Cl, are obtained. This salt can easily be 
prepared from the pure pyrolignite of lime, and it has been 
suggested by Condy to employ this salt as a means of preparing 
pure acetic acid.^ Acetic acid is now manufactured in Newcastle- 
on-Tyne according to this process, although it does not appear 
to have been generally adopted. There seems to be a prejudice, 
although quite an unfounded one, against the use of the acid 
thus prepared. 

The sodium salt is now always employed for the preparation 
of concentrated acetic acid, as this salt can be easily obtained. 
The water of crystallization which it contains must be first 
removed by heating, and at last the temperature is raised up 
to the fusing point of the anhydrous salt. This operation 
was formerly conducted in iron boilers, in which very serious 
explosions took place, owing to the top layers of hydratcd salt 
falling into the fused mass at the bottom. Sheet-iron pans 
are now employed, 6 feet long, 4 feet wide, and 2 feet deep. 
Care has to be taken that no sparks fall into the fused mass, as 
if this is the case the whole takes fire and bums aw^ay like tinder. 
After cooling, the solidified crystalline mass is broken up into 
small pieces and distilled with the requisite quantity of strong 
sulphuric acid. The distillate is not anhydrous acetic acid, but 
contains a few per cents, of water, owing to the fact that the 
sulphuric acid used for the decomposition is never anhydrous, 
and that in the operation of fusing a certain quantity of sodium 
carbonate is formed. It is, however, easy to obtain pure acetic 
acid from this product, for, on distillation, an aqueous acid 
passes over first, and afterwards the anhydrous acid. This 
latter separates out in crystals when it is cooled, and the liquid 
portion being poured off, the crystals are melted again, so that 
by a repetition of this operation pure glacial acetic acid is 
obtained. 

319 Properties. — Pure acetic acid is a colourless liquid having 
a strongly acid and pungent smell and taste. It crystallizes on 
cooling in large transparent glistening tables which melt at 
16°*7.^ If melted in a closed vessel and allowed to cool down, 
acetic acid retains its liquidity, even at a temperature below 
0**, but on opening or shaking the vessel, or on dropping in a 

* Spon's Ennjel. Jnduntr, Arts, 25. 

* KiKlorif, Bcr, l^utuch, Ckem, Oft. iii. 390. 



PROPERTIES OF ACETIC ACID. 



493 



small piece of solid acid, the whole solidifies, and the tempera- 
ture rises to 16°'7. A small addition of water lowers the melt- 
ing point considerably, so that an acid containing 13 per cent, 
of water melts below 0°, and one containing 38 per cent, of 
water and corresponding to the formula CgH^Og -|- 2H2O has a 
melting-point of — 24°. If more water be added the melting- 
point rises again. ^ The specific gravity of acetic acid at 0° is 
1*0800 (Kopp), whilst at 15"* it possesses the specific gravity of 
1*0553 (Oudemanns).^ If water be added, the specific gravity 
rises at first until an acid containing 70 per cent, is obtained. On 
a further addition of water the specific gravity remains unaltered, 
so that aqueous acetic acid containing 76*5 to 80 per cent, 
possesses the same specific gravity, namely, according to van 
Toom * and Roscoe,* 10754 at 15°*5. The specific gravity then 
diminishes, so that an acid containing 43 per cent, has at 15° 
the same specific gravity as the anhydrous acid (Oudemanns). 
Hence it follows that the concentration of the aqueous acid 
caunot be determined, as that of alcohol can be, by the specific 
gravity, but trituration with an alkali must be employed. 
Riidorff has shown that the melting-point of the pure acid is 
considerably lowered by the presence of a slight trace of water, 
and upon this fact he has founded a method for determining 
the strength of high percentage acetic acid.^ This was 
formerly ascertained by shaking up the acid, together with oil 
of lemon, and observing how much of this dissolved. The 
German Pharmacopoeia still states that 10 parts of pure con- 
centrated acetic acid dissolve 1 part of this oil A dilute acid 
takes up less, and in proportion to the quantity of water which 
it contains. 

Basil Valentine was aware that vinegar when distilled yielded, 
to begin with, a weaker, and later on a stronger acid ; and in his 
treatise, ** Vom grosscn Stein der uralten Weisen," he distin- 
guishes in this respect between the behaviour of acetic acid and 
that of alcohol, and he says that *'in the distillation of spirit of 
wine the spirit comes over first and the phlegma last ; when, 
however, this by a long-continued warmth has been converted 
into vinegar, its spirit is not so volatile as before, and on dis- 
tilling the vinegar the aquosity passes over first and the spirit 
last." ^ It has already been stated that Lowitz found that a low 



* Grimanx, Compt. Bend. Ixxvi. 486. 

* Joum, Praht, Chem. vi. 171. 

* Loc cit. 



' Jaum, Prakt. Chem. \\ 452. 
* Jonrn. Chem, Soc. xv. 270. 
'» /W. Pdracusy p. 51. 



. . a 



:>'' 



-^'■^ .■« «« •> '. *« 



' ■ ^ 



- tt • ^ ■ *«^«M«^ 



-\ - . . 



• • »- 






• .' .■ ../ • 



1 



r 
1 






•. •■' 



' I f* /. .