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TRANSACTIONS 



OF THE 



Amfrtran 
lEUttrorhi^mtral Sorirtti 



VOLUME XLIll 



FORTY-THIRD GENERAL MEETING 

NEW YORK CITY 
MAY 3, 4 AND 5, 1923 






PUBLISHED BY 

Ollir AmrrUan €lfrtrori|fmiral ^orWy 

AT THE OFFICE OF THE SECRETARY 

COLUMBIA UNIVERSITY, NEW YORK ClTY 

1923 






TRANSACTIONS 



OF THE 



Ammran 



VOLUME XLIII 



FORTY-THIRD GENERAL MEETING 

NEW YORK CITY 
MAY 3, 4 AND 5, 1923 



T 



t.. ^' 



PUBLISHED BY 

®l|p Amrrtran ^Itttrotiftmxcui ^orirty 

at the office of the secretary 
Columbia University, New York City 

1923 



TV 

Copyright 1923 bj- the Amefiean Electrochemical Society, w, iL,0 



Permission to reprint parts of the Transactions is herehj- granted 
to current periodicals, provided due credit is given. 



The Society is not responsible for the statements and opinions 
advanced in papers or in discussion thereon. 



Prices of Volumes ;I to XLIII (excepting Vols. I, II, III, VII, 
XXIX and XXXI), to non-members, $6.50 per copy; to members, 
$2.50, excepting Vols. XLI and XLII, which are $4.00 each; to 
public libraries, colleges, scientific societies and journals, $4.00. 
Volumes I, II, III, VII, XXIX and XXXI are double above prices. 
Prices are for volumes bound in cloth, and include delivery within 
the postal union. 



When the stock of anj- volume has been, reduced to 25 copies 
(as Vol. Ill), the sale is limited to those purchasing the given 
volume as part of a complete set. 



Complete sets will be sold to anybody at 25 per cent discount 
on above prices ; members may obtain the volumes necessary to 
complete their sets at 25 per cent reduction on above prices. 



WARE BROS. COMPANY. PRINTERS 
1010 ARCH ST.. PHILA. 



OFFICERS OF THE SOCIETY 



PRESIDENT 

A. T. HINCKLEY 

Term expires 1924 
PAST-PRESIDENT 

C. G. SCHLUEDERBERG 

Term expires 1924 
VICE-PRESIDENTS 

H. C. PARMELEE LAWRENCE ADDICKS 

A. H HOOKER G. K. ELLIOTT 

W. S. LANDIS HENRY HOWARD 

Terms expire 1924 Terms expire 1925 

MANAGERS 

CARL HERING E. F. CONE F. M. BECKET 

J. V. N. DORR W. M. CORSE C. B. GIBSON 

F. A. J. FITZ GERALD WM. BLUM R. A. WITHERSPOON 

lerms expire 1924 Terms expire 1925 Terms expire 1926 

TREASURER 

F. A. LIDBURY 

Term expires 1924 
SECRETARY 

COLIN G. FINK, Columbia University, New York City 

Term expires 1924 



COMMITTEES 



PUBLICATION COMMITTEE 

F. A. J. FiTz Gerald, Chairman 
CouN G. Fink, Ex Officio A. T. Hinckley, Ex Officio 

H. M. Goodwin Wm. Blum 

H. C. Parmelee E. F. Cone 

Terms expire 1924 Terms expire 1925 



COMMITTEES — ContinuMl 

COMMIITEE ON I,OCAL SECTIONS 

F. J. Tone, Chairman Colin G. Fink C. G. Schluederberc 



PATENT COM>UTTEE 

L. H. BaEkeland, Chairman F. G. CoTTRELL 



E. J. Prindle 



PUBLIC KELATION8 COM3IITTEE 



A. T. Hinckley, Chairman 



W. D. Bancroft 
Carl Hering 
C. G. Burgess 
E. G. AcHESoN 
L. H. Baekeland 

W. H. W.\LKER 

W. R. Whitney 



F. A. LiDBURY 

Lawrence Addicks 
F. A. J. FitzGerald 
Colin G. Fink 
F. J. Tone 
W. S. Landis 
AcHESON Smith 



C. G. Schluederberg 



MEMBERSHIP COMMITTEE 

E. L. Crosby, Chairman 

M. deK. THOMPSON, Cambridge, Mass. J. W. BECKMAN, Oakland, Calif. 



L. E. SAUNDERS, Worcester, Mass. 
G. B. HOG.\BOOM, Waterbury, Conn. 
H. C. PARMELEE, New York, N. Y. 

C. F. ROTH, New York, N. Y. 
E. F. KERN. New York, N. Y. 

J. A. SEEDE, Schenectady, N. Y. 
H. W. GILLETT. Ithaca, N. Y. 
G. H. CLAMER, Philadelphia, Pa. 
R. E. ZIMMERMAN, Pittsburgh, Pa. 
J. E. ISENBERG, State College, Pa. 

D. A. LYON, Washington, D. C. 
P. J. KRUESI, Chattanooga, Tenn. 
THEODORE SWANN, Anniston, Ala. 
L. A. DREFAHL, Cleveland. O. 

T. F. BAILY, Alliance, O. 
G. K. ELLIOTT, Cincinnati, O. 
W. K. BOOTH, Chicago, 111. 
O. P. W.\TTS. Madison, Wis. 



C. E. WILLIAMS, Seattle, Wash. 

F. T. KAELIN, Montreal, Canada. 

J. T. BURT-GERRANS, Toronto, Canada. 

J. H. BUTTERS, Hobart, Tasmania 

HANS LANDOLT, Turgi, Switzerland 

BIRGER CARLSON, Stockholm, Sweden 

B. BERG-HANSEN, Christiania, Norway. 
K. B. QUIN.XN, W. Somerset, Cape 

Province, S. Africa. 

C. A. KELLER, Paris, France. 

H. F. ETCHELLS, Sheffield, England. 
W. E. HUGHES, Seaford, England. 
F. GIOLITTI, Torino. Italy. 
F. FOERSTER, Dresden, Germany. 
J. BABOROVSKY, Brno, Crecho- 
Slovakia. 

VOGORO KATO, Tokio, Japan. 

JEN CHOW. Shanghai, China. 

A. H. ATEN, Amsterdam, Netherlands. 



WAYS AND MEANS COMMITTEE 

H. B. CoHO. Chairman 
Lawrence Addicks Carl Hering 

Colin G. Fink F. A. Lidbury 

H C. Parmelee 



DIVISIONS OF THE SOCIETY 

BXECTROTHERMIC DIVISION 

G. K. Elliott, Chairman 
DoRSEY A. Lyox, Vice-Chairman L. C. Judson, Secretary-Treasurer 

Membera-at-L.arg'e 

James H. Parker F. M. Becket 

W. J. Priestley Bradley Stoughtox 

Terms expire 1924 Terms expire 1925 

ELECTBODEPOSITION DIVISION 

S. Skowronski, Chairman 
Chas. a. Mann, Vice-Chairman Wm. Blum, Secretary-Treasurer 

Meinber8-at-LiarK« 

Lawrence Aduicks F. R. Pyne 

F. C. Mathers M. R. Thompson 

Terms expire 1924 Terms expire 192S 

Foreign Representatives 

W. E. Hughes, Seaford, England Bertram Wood, Hobart. Tasmania 



TECHNICAL COMMITTEES 

I'RIMARV BATTERIES 

C. F. Burgess, Chairman D. L. Ordway 

SECONDAKT BATTERIES 

P. G. Salom, Chairman O. W. Brown 

ELECTRO ANAI.Y8I8 

H. S. LuKENS, Chairman Geo. S. Forbes 

RADIO ACTIVITY 

S. C. LiND, Chairman H. S. Miner 

CHLORINE AND CAISTIC 

E. M. Sergeant, Chairman Hugh K. Moore L. D. Vorce 

CORROSION 

Colin G. Fink, Chairman W. M. Corse W. D. Richardson 

FIXED NITROGEN 

W. S. Laxdis, Chairman Arthur B. Lamb Frank S. McGregor 

WATER POWER 

J. H. Harper, Chairman J. L. YardlEY H. J. Pierce 

ORGANIC ELECTROCHEMISTY 

C. J. Thatcher, Chairman Alexander Lowy 

ELECTROCHEMISTRY OF GASEOUS CON'DrCTION 

Duncan MacRae, Chairman Wm. R. Morr 

INSUT^ATING OILS AND VAR^^SHES 

H. C. p. Weber, Chairman 
C. D. HocKEs C. J. Rodman Christian Dantsizex 

RADIO B.4TTERJES 

C. F. Burgess, Chairman Geo. W. Vixal C. A. Gillixgham 



LOCAL SECTIONS OF THE SOCIETY 

Philadelphia Section 
Carl Herixg, Chairman, Philadelphia, Pa. 
S. S. Sadtler, Secretary, Philadelphia, Pa. 

New York Section 

P. D. Merica, Chairman 

P. D. V. ManxXing, Secretary-Treasurer, 50 E. 41st St. 

Pittsburgh Section 

C. B. GiBSOX, Chairman, E. Pittsburgh, Pa. 

S. L. GooDALE, Secretary-Treasurer, Pittsburgh, Pa. 

Niagara Falls Section 

E. AI. Sergeant, Chairman, Niagara Falls, N. Y. 

L. C. JuDSox, Secretary-Treasurer, Niagara Falls, N. Y. 



TABLE OF CONTENTS. 



PAGE 

Portrait of President A. T. Hinckley Frontispiece 

Proceedings of the Forty-third General Meeting 1 

Portrait of Dr. Edward G. Acheson. (Honorary Member) 5 

Dr. Edward G. Acheson and His Work— F. A. J. FitzGerald 5 

Members and Guests Registered at the Forty-third General Meeting 18 

PAPERS. 

Presidential Address — Opportunities for the American Electrochemist 

Abroad — C. G. Schluederberg 21 

PAPERS ON "ELECTRODE POTENTIALS." . 

Newer Aspects of Ionization Problems — Hugh S. Taylor 31 

Oxygen Overvoltage of Artificial Magnetite in Chlorate Solutions — 

H. C. Howard 51 

The Effect of Current Density on Overvoltage — M. Knobel, P. Caplan 

and M. Eiseman 55 

Electrotitration wMth the Aid of the Air Electrode — N. Howell Furman. 79 

The Hydrogen Electrode in Alkaline Solutions — A. H. W. Aten 89 

Electrolytic and Chemical Chlorination of Benzene — Alexander Lowy 

and Henry S. Frank 107 

The Reactions of the Lead Storage Battery — M. Knobel 99 

Notes on the Electrodeposition of Iron — Harris D. Hineline 119 

The Influence of the Base Metal on the Structure of Electrodeposits — 

W. Blum and H. S. Rawdon See Vol. 44 

Current Distribution and Throwing Power in Electrodeposition — H. E. 

Haring and W. Blum See. Vol. 44 

The Electrodeposition of Nickel on Zinc— A. Kenneth Graham. See Vol. 44 
The Effect of Iron on the Electrodeposition of Nickel — M. R. 

Thompson See Vol. 44 

Heat Insulating Materials for Electrically Heated Apparatus — J. C. 

Woodson 127 

Methods of Handling Materials in the Electric Furnace and the Best 

Type of Furnace to Use — Frank W. Brooke 149 

vii 



PAGE 

The Conversion of Diamonds to Graphite at High Temperatures — 

M. deKay Thompson and Per K. Frolich 161 

The Relation between Current, Voltage and the Length of Carbon 

Arcs— A. E. R. W'estman 171 

Electric Furnace Detinning and the Production of Synthetic Gray Iron 

from Tin-Plate Scrap — C. E. Williams, C. E. Sims and C. A. 

Newhall 191 



PAPERS ON "THE PRODUCTION AND APPLICATION 
OF THE RARER METALS.'" 

Present Status of the Production of Rarer Metals — C. James 203 

The Preparation of Fused Zirconium — Hugh S. Cooper 215 

Experiments with Uranium, Boron, Titanium, Cerium and Molybdenum 

in Steel— H. W. Gillett and E. L. Mack 231 

Some Effects of Zirconium in Steel — F. M. Becket 261 

Inherent Effect of Alloying Elements in Steel — B. D. Saklatwalla 271 

Notes on the Metallurgy- of Lead Vanadates — Will Baughman 281 

Preparation of Metallic Uranium — R. W. Moore 317 

The Reduction of Some Rarer Metal Chlorides by Sodium — M. A. 

Hunter and A. Jones See Vol. 44 

Experiments Relative to the Determination of Uranium by Means of 

Cupferron — Jas. A. HoUaday and Thos. R. Cunningham 329 

Cobalt— Its Production and Uses— C. W. Drury 341 

Chromizing — F. C. Kelley 351 

The Preparation of Platinum and of Platinum-Rhodium Alloy for 

Thermocouples — Robert P. Neville 371 

Investigations on Platinum Metals at the Bureau of Standards — Edward 

Wichers and Louis Jordan 385 

Some Notes on the Metals of the Platinum Group — Fred E. Carter. . . .397 



Volume XLIII 1923 



TRANSACTIONS 

OF THE 

Autmran l£UrtrorI|^ittiral ^nmtg 



PROCEEDINGS 

CONDENSED MINUTES AND RECORD OF THE FORTY-THIRD GENERAL 

MEETING OF THE SOCIETY, HELD AT THE COMMODORE HOTEL, 

NEW YORK CITY, MAY 3, 4 AND 5, 1923. 

The total registration at this meeting was 254, of whom 168 
were members and 86 guests. 

PROCEEDINGS OF WEDNESDAY, MAY 2, 1923 

The registration of Society members and guests began at 6.00 
P. M. on the mezzanine floor of the Commodore Hotel. At 
7.00 P. M. the Board of Directors met at dinner for the purpose 
of conducting its annual business meeting. 

PROCEEDINGS OF THURSDAY, MAY 3, 1923 

The meeting convened at 9.30 A. M. with President C. G. 
Schluederberg in the Chair. Having but recently returned from 
a trip to the Far East, the President expressed his gratitude at 
being back in the United States again, and, on behalf of the 
Society, heartily welcomed the members and guests present. He 
then called upon Dr. Wm. G. Horsch, who had arranged for 
the Symposium on "Electrode Potentials," to assume the Chair. 
Dr. Horsch briefly mentioned that the subject of electrode poten- 
tials is one which lies particularly within the field of the electro- 
chemist, and that the papers and discussions of this session should 
give rise to a rather comprehensive cross-section of the line of 



2 PROCEEDINGS. 

progress at the present time. Papers by the following authors 
were presented and are printed, together with discussions, in 
these Transactions : Hugh S. Taylor; H. C. Howard; M. Knobel, 
P. Caplain and M, Eiseman ; N. Howell Furman ; A. H, W. 
Aten ; M. Knobel ; Alexander Lowy and H. S. Frank. 

At 11.30 the meeting adjourned. Within a quarter of an hour, 
members and guests were conveyed by special buses to the plant 
of the McGraw-Hill Co., Inc., where a complimentary luncheon 
was served. This was followed by an inspection trip through 
the various departments of the printing and publishing plant. 
Moving pictures depicting the construction and operation of the 
Diesel engine concluded the visit, the members returning to the 
Commodore Hotel to attend the afternoon session. 

At 2.30 P. M. President Schluederberg opened the annual 
business meeting of the Society. Secretary Fink presented the 
reports of the Board of Directors and of the Secretary. In the 
latter report it was pointed out that since the Baltimore meeting 
the Society had published and distributed four volumes of the 
Transactions (Vol. 39, 40, 41 and 42), thus bringing the publi- 
cation work up to date. Following the presentation of this 
report, Dr. Hering offered the following resolution : That a 
vote of thanks be expressed to the Secretary and his office for 
having brought the volume publications up to date. The motion 
was unanimously carried. The above reports, together with that 
of the Treasurer are included in subsequent pages of the pro- 
ceedings. 

The next order of business included reports of Standing 
Committees. Dr. C. F. Burgess presented the report of his 
committee on dry cells, which indicated that in 1914, 17,092,438 
dry cells were sold in this country at a valuation of $8,719,164, 
while in 1919 the number had increased to 173.754,676 at a 
valuation of over $25,000,000. To promote rapid work and to 
avoid unnecessary du])lication of effort this committee made the 
following recommendations : 

1. That a committee on dry cells be appointed for the coming 
year, with instructions to oft'er its co-operation to the Bureau of 
Standards in standardization of tests for dry cells in various kinds 
of radio service. 



PROCEEDINGS. 3 

2. That members of the American Electrochemical Society who 
are engaged in dry cell manufacture, and who are desirous of 
contributing to and taking part in this work, indicate their desires 
to the Bureau of Standards. 

Dr. S. C. Lind presented the report of the Radio Activity Com- 
mittee, in which it was especially pointed out that in the produc- 
tion of radium in the United States there has been a marked 
cessation of activity. This is directly due to the discovery and 
development of a large deposit of high grade radium-bearing 
uranium ore in the Belgian Congo by the Katanga Copper Co. 
It was the recommendation of Dr. Lind's committee that the 
Society undertake to concentrate in its Transactions the results 
of numerous investigations, in the field of radio activity, which 
are published in such a widely scattered range of journals. 

The report of the Organic Electrochemistry Committee was 
presented by its Chairman. Dr. C. J. Thatcher. The progress 
being made in this field will be discussed extensively at a sym- 
posium to be held at the Spring meeting, 1924. 

^Ir. A. T. Hinckley presented the report of his committee on 
membership. The essential data of this report are published in 
following pages. 

Chairman FitzGerald of the Publication Committee presented 
a report which in part is as follows : 

To the Board of Directors. American Electrochemical Society: 
During the year 1922-23 your committee has received and 
examined 98 papers. Of these 20 were rejected, 27 were returned 
to the authors for revision, 48 were accepted without change and 
3 were withdrawn. 

Every paper is sent to at least 2 examiners. Some papers 
during the past year have been reported on by 5 examiners, and 
several papers have been reported on by 3 examiners, before 
final action by the committee. This change in the routine ex- 
amination of papers has made it necessary to insist on an earlier 
date for the submission of papers than has formerly been the 
practice, and the ruling of the Publication Committee as to the 
latest date for receiving papers will in future be rigidly enforced. 
A new rule of the Publication Committee in relation to papers 



4 PROCEEDINGS. 

submitted for symposia is that one of the two examiners to whom 
a symposium paper is submitted shall be the member in charge of 
the symposium. The object of this rule is to avoid embarrass- 
ments which are apt to arise when the member in charge of the 
symposium has invited papers which the Publication Committee 
is disposed to reject. 

Prior to presenting the report of the Tellers of Election, the 
Chair read a communication from H. C. Parmelee in which he 
withdrew his name from the report in favor of A. T. Hinckley. 
The Chair then read 

THE REPORT OF THE TELLERS OF ELECTION 

The following is a list of votes cast in the election of officers 
for the year 1923-1924: 

President: A. T. Hinckley, 246. 

Vice-Presidents: Lawrence Addicks, 212 ; G. K. Elliott, 148 ; 
Henry Howard, 117; Dorsey Lyon, 103; W. Lash Miller, 71; 
W. R. Mott, 60 ; A. T. Hinckley, 2. 

Managers: F. M. Becket, 208; C. B. Gibson, 185 ; R. A. With- 
erspoon, 149; G. B. Hogaboom, 99; D. B. Rushmore, 51; Law- 
rence Addicks, 1. 

Treasurer: F. A. Lidbury, 240. 

Secretary: Colin G. Fink, 244. 

Void Ballots, 33. ^ ata ttt 

Lincoln T. Work 

^ ^ ' Arthur K. Doolittle 

The President announced the following elections, as the result 
of the Tellers' report: 

President: A. T. Hinckley. 

Vice-Presidents: Lawrence Addicks, G. K. Elliott. Henry 
1 If)ward. 

Managers: F. M. Becket, C. B. Gibson, R. A. Witherspoon. 
Treasurer: F. A. Lidbury. 
Secretary: Colin G. Fink. 

Following this announcement the Chir requested Mr. Acheson 
Smith to escort President-elect Hinckley to the platform. 




(5ti:c<.a^r^ ;^ /^^X^^^iO^^^ 



PROCEEDINGS. 5 

DR. EDWARD G. ACHESON MADE HONORARY MEMBER 

President Schluederberg announced that, at the meeting of the 
Board of Directors held Wednesday evening, Dr. Edward G. 
Acheson was elected to Honorary Membership upon official rec- 
ommendation from 15 members of the Society. Dr. Hering 
escorted Dr. Acheson to the platform, whereupon Mr. F. A. J. 
FitzGerald delivered the following introductory address on E. G, 
Acheson and his work. 



DR. EDWARD G. ACHESON AND HIS WORK 

By F. A. J. FitzGerald.' 

The twenty-first anniversary of the American Electrochemical 
Society has a special significance. It is fitting that its coming 
of age should be marked by the conferring of its Honorary 
Membership on one whose name is universally known for what 
he has done in advancing electrochemical industry. Inasmuch as 
I had the good fortune to serve an eight years' apprenticeship 
with Dr. Edward G. Acheson when some of his inventions were 
made, I can perhaps contribute something in the way of an appre- 
ciation of his work in electrochemistry. 

You have no doubt observed that some naive amateurs inter- 
ested in industrial research seem to consider the objective of the 
work as something of minor importance compared with the pro- 
cess of reaching it; but actually the conception of an invention 
often demands a rarer gift than the working out of its details. 
Dr. Acheson's work is characterized particularly by this gift of 
choosing objectives to which he devotes his inventive genius. 

One of his early objectives was the production of an abrasive 
material, the properties of which would surpass anything that 
could be obtained from natural sources, for he visualized clearly 
the vast industrial importance of such a material. So he made 
his well-known experiment with the arc light electrode and the 
plumber's soldering bowl filled with clay and powdered coke, 
which resulted in the discovery of carborundum and the building 
of a miniature electric furnace for its manufacture. This, I think, 

» FitzGerald Labs., Niagara Falls, N. Y. 



6 PROCIIEDINGS. 

illustrates clearly what I mean by Achesoii's faculty of seeing a 
valuable objective, the direction of experimental work which 
would have a great industrial future. 

Acheson's subsequent work in creating the artificial abrasive 
industry illustrates another characteristic of his which is so fre- 
quently lacking in those who may perhaps equal him in original 
ideas; that characteristic is his ability to concentrate on his sub- 
ject. The late William De Morgan, probably most widely known 
as the author of those remarkable series of novels which began 
with "Joseph Vance," devoted most of his life to the manufacture 
of pottery, and did wonderful work in that field with his inventive 
genius ; but according to one who knew him well, "his mind was 
ever full of original methods and ideas on all sorts of subjects," 
and "it was perhaps, to some extent, the wide range of William 
De Morgan's inventive and creative ability which tended in a 
measure to hamper the success of the pottery."^ 

Like De Morgan, Acheson's mind is full of original methods 
and ideas ; but these are not allowed to interfere with the develop- 
ment of any particular objective he has in mind. Note how in 
the early days of carborundum manufacture he observed and 
recognized the value of the artificial graphite produced by the 
decomposition of silicon carbide ; how he realized the remarkable 
refractory qualities of silicon carbide ; how he made calcium 
carbide in his electric furnace ; but he did not allow these things 
to divert his attention from the great objective, the production 
of carborundum, which would revolutionize the abrasive industry, 
on a large scale. 

Observe also that Acheson fully recognized the importance of 
basing his work on fundamental scientific principles. This may 
not appear a surprising thing to us at the present day, for we 
would certainly be astonished at an electrochemical plant that 
attempted to run without scientific control. But when Acheson 
made his first little vial of carborundum he sold it at 40 cents 
a carat and devoted the proceeds to the purchase of a microscope, 
and when he organized the Carborundum Company with its little 
100-kilowatt plant in Monongahela he at once established a chem- 
ical laboratory in charge of a German chemist, in those days 

2 "William De Morgan anH His wife" by A. M. W. Stirling. Henry Holt and Co., 
1922. 



PROCEEDINGS. 7 

believed to be the best variety. This was an extraordinary thing 
for an abrasive manufacturer in those days, and led to the desig- 
nation of the Carborundum Company as a plant "run by educated 
blockheads." 

This was the beginning of the manufacture of artificial abra- 
sives and it is not necessary to tell you what that electrochemical 
industry has become; but I may note that the world production 
of electric furnace abrasives in 1895 came from Acheson's 100- 
kilowatt furnace in Monongahela, while 25 years later at Niagara 
Falls alone the power used in this industry amounted to 20,000 
kilowatts. 

In the development of Acheson Graphite, we again have an 
excellent example of his faculty for selecting an objective that 
would develop into an important industry. Acheson observed 
the formation of graphite in his early carborundum furnace ; but 
it was not until several years later, after carborundum had already 
become an important industry and when he undertook to graph- 
itize carbon anodes at the Carborundum Company's plant for use 
in the Castner caustic soda cell, that he concentrated his energy 
on the building up of the graphite industry. It is needless to 
dwell on the value of Acheson graphite in electrolytic and electro- 
thermic processes ; but it will be interesting to consider some other 
work relating to its development. 

Persistent refusal to accept defeat is a quality of the highest 
value in war and in pioneer work in a new process or industry. 
There is another quality, however, that is perhaps rarer and 
equally valuable and this is the faculty of recognizing a tactical 
error and effecting a strategic retreat. In the development of the 
graphitizing industry, after much experimental work was done 
on the production of bulk graphite from anthracite coal, Dr. 
Acheson designed a furnace for its production that has since 
figured prominently in text books both in this country and abroad, 
and yet that furnace was never run commercially. On paper it 
looked excellent; it was built and the special electrical apparatus 
required for it obtained and set up; but about six hours' trial 
convinced Dr. Acheson that it was useless as a commercial ap- 
paratus and it was then and there sentenced to the scrap pile. 

The thing I wish to emphasize is that Acheson saw at once that 



8 PROCEEDINGS. 

the design was faulty ; that it would be throwing away money to 
try to get it to work, and that complete abandonment of the scheme 
was the proper course in spite of the large expenditure already 
incurred. It is worth noting that subsequent experience has 
completely demonstrated the soundness of Acheson's judgment ; 
but there can be no question that it required a high order of 
courage on his part to resist the temptation of trying to make an 
apparatus work on which so much had been spent. 

A large and important use for graphite is in the manufacture 
of crucibles. When Acheson started experimental work on these 
he found that the clay bond used in making them was imported, 
the reason given for this being that, while in this country we had 
plenty of refractory clays, none of these combined sufficiently 
high plasticity with refractory qualities. Acheson reacted char- 
acteristically to this, and determined to investigate the plasticity 
of clays. He apparently felt, as I think he always does, that 
it is not necessary to depend on natural sources for things of 
this sort, but that they can be better made by man. 

He immediately began experimental work based on the effect 
of organic substances on clay, and two or three days later, on a 
Monday morning, he came into the laboratory carrying a big 
load of straw, which he deposited on the bench. He then told me 
that, on the day before, his children had been having at their 
Sunday School the story of the Egyptian bondage of the Children 
of Israel, and the difficulties they met in making brick without 
straw. Why, he asked, did they need straw for their brick? 
Surely not as a mere re-enforcement, but because the aqueous 
extract of the straw gave to the clay the plasticity and mechanical 
strength which he was seeking. He began the straw experiments 
that day, and I worked on big wash tubs of clay and aqueous 
extracts of straw nearly all night with Dr. Acheson, whose health 
was bad at the time, following up and directing the experiments 
through the long distance telephone. Thus Egyptianized clay was 
discovered. 

It was about this time also that Acheson was working on 
Siloxicon ; but I can not do more than mention it by name so as 
to leave a little time for the consideration of one more of his 
inventions. 



PROCEEDINGS. 9 

I have already called attention to Dr. Acheson's keen appre- 
ciation of what is needed. At the present day we have all sorts 
of problems, the handling of which will profoundly affect the 
future of civilization. We have reparations, the disastrous effects 
of phrases like "self-determination," German marks, etc., but 
there is none of the problems more important than that of the 
mineral oil fields. Twenty years ag'o the average man was not 
worrying about mineral oil, today he is thinking of it seriously. 
But even now he is only thinking of it as a source of fuel, more 
particularly as supplying the wants of his motor car or his Ford. 

But fuel is not the most important point ; we have other sources 
of fuel — even our powerful army of moral uplifters can not 
amend the constitution of nature. Careful study of the subject 
shows that the great value of mineral oil lies in its lubricating 
qualities, and it is becoming clearer and clearer now that the 
strong argument for its conservation is found in its importance 
as a lubricant. Twenty years ago, Acheson saw this clearly, and 
determined to turn his inventive genius towards finding a sub- 
stitute for mineral lubricating oils, or at least something that 
would lead to their economical use. 

It would take too long to follow the development of methods 
of producing a nearly chemically pure non-coalescing graphite 
for lubrication, nor is this necessary because the technical details 
of this work are probably well known to most of you. It is suffi- 
cient to note that the inception of the work on deflocculated 
Acheson graphite was similar to that which characterizes other 
fields in which Acheson worked, and that in its development we 
find the same ingenuity, resourcefulness and persistence which 
distinguish his other work. 

Those of you who are familiar with Acheson's work will under- 
stand how inadequate this review is. I hope, however, that I 
have said enough to show to those unacquainted with the details 
of his work why, in the history of electrochemical industry, one 
of the great names is that of Edward Goodrich Acheson. 



Following the above address. President Schluederberg pre- 
sented Dr. Acheson with a certificate of Honorary Membership. 
In response. Dr. Acheson spoke, in part, as follows : 

2 



lO PROCEEDINGS. 

"I appreciate most highly the honor you are conferring upon 
me. It is a matter of much gratification to me to know that I 
assisted in the organization and the early work of our Society. 
I am gratified to know that it has become a national society of 
considerable magnitude, with a foreign membership of which we 
can be proud. It has done good work in the past, and I hope and 
believe it will do more valuable work in the future. I hope that 
it will continue to hold its place among the national societies, and 
that we will all have good reason to be proud of having been 
enrolled in its membership." 

President Schluederberg then invited President-elect Hinckley 
to assume the Chair during the presentation of his presidential 
address, entitled, "Opportunities for the American Electrochemist 
Abroad."' This address is printed in full in this volume. 

Thereafter papers by the following were presented for dis- 
cussion : W. Blum and H. S. Rawdon ; H. E. Haring and W. 
Blum ; A. Kenneth Graham ; M. R. Thompson ; H. D. Hineline. 
These papers, with the exception of that of H. D. Hineline, will 
be published in Volume 44 of the Transactions. The final paper 
of this session was by Will Baughman, on lead vanadates. It is 
printed in this volume. 

At 6.00 P. M. the Council of the Electrothermic Division held 
a dinner-meeting. This was followed by a meeting of the Advi- 
sory Committee to the Bureau of Mines on electrometallurgical 
work. 

PROCEEDINGS OF FRIDAY, MAY 4, 1923 

The session was called to order at 9.30 A. M. by President 
Schluederberg, and the results of the election of officers to the 
Electrothermic Division and the Electrodeposition Division for 
1923-1924 were announced. The officers of these divisions are 
printed on the first pages of this volume. 

The technical session began with the presentation, by title, of 
papers by J. C. Woodson and Frank W. Brooke. Both these 
papers had been read, but not preprinted, at the 42nd meeting of 
the Society. Then followed the presentation for discussion of 
papers by the following authors : M. deKay Thompson and Per 
K. Frolich; A. E. R. Westman ; C. E. Williams. C. E. Sims and 
C. A. Newhall ; C. W. Drury ; F. C. Kelley. All the above papers, 



PROCEEDINGS. 1 1 

with discussions, are printed in this volume. The meeting ad- 
journed at 11.30. 

At 12 o'clock members and guests left by train for Westport, 
Conn. At the kind invitation of Dr. J. V. N. Dorr and Mr. H. N. 
Spicer, a visit was made to the Westport Mill of the Dorr Co. 
The members were also guests at an enjoyable luncheon served 
amid the beautiful and idyllic surroundings of the mill. Later 
in the afternoon, members and guests went on to the Westport 
Country Club, where a golf tournament was staged by the men, 
while the ladies enjoyed bridge and walks. During the dinner, 
which was served under the auspices of the Xew York Section 
of the Society, and for the successful arrangement of which 
Mr. Irving Fellner was responsible, the following golf prizes 
were awarded : An engraved silver loving cup, donated by Dr. 
Dorr, to Frank J. Vosburgh ; a niblick, as booby prize, to -Robert 
Burns. This was followed by the clever rendition of a funny 
song, by Messrs. Lidbury and Hinckley, which, as a parody of 
"Mr. Gallagher and Mr. Shean," characterized numerous mem- 
bers of the Society. Thereafter dancing was enjoyed by many, 
and it was with great reluctance that the party returned to New 
York later in the evening. 

PROCEEDINGS OF SATURDAY, MAY 5, 1923 

On Saturday, at 9.15 A. M., President Schluederberg opened 
the meeting by introducing Dr. F. M. Becket, who had arranged 
for an interesting and comprehensive session on the "Production 
and Application of the Rarer ^letals." Dr. Becket assumed the 
Chair and papers were presented by the following authors : 
C. James; H. S. Cooper; H. W. Gillett and E. L. Mack; F. M. 
Becket; B. D. Saklatwalla; R. W. Moore; J-. A. Holladay and 
T. R. Cunningham ; R. P. Neville ; Edward Wichers and Louis 
Jordan ; F. E. Carter. These papers, with discussions, are printed 
in these Transactions. Another paper which had been contributed 
toward this symposium, but arrived too late to permit of its 
presentation at this meeting, will be printed in the subsequent 
volume, vis., 44. This paper is entitled "The Reduction of Some 
Rarer Metal Chlorides by Sodium," by ^M. A. Hunter and A. 
Jones. In concluding the technical program, President Schlueder- 



12 PROCEEDINGS. 

berg, on behalf of the Society, thanked Dr. Becket for his suc- 
cessful efforts in procuring the many excellent papers for this 
session. He also expressed thanks to those who had contributed 
papers and discussion to the meeting. 

Prior to adjourning the meeting, Dr. Hering offered the fol- 
lowing 

RESOLUTION OF THANKS. 

Resolved: That a vote of thanks be given to the following for 
having made this forty-third meeting of the American Electro- 
chemical Society such a success : 

The Dorr Co., and especially to Dr. J. V. N. Dorr and Mr. 
H. N. Spicer. 

The Westport Countr}^ Club. 

The McGraw-Hill Co. 

The New York Local Section. 

The Local Committee, and especially to Mr. Irving Fellner, its 
active chairman. 



ANNUAL REPORT OF THE BOARD OF DIRECTORS 

To the Members of the American Electrochemical Society: 

The following are some of the important items of business 
transacted by your Board of Directors during the past year: The 
following constitutional amendment, effective January 1, 1923. 
submitted over the signatures of 15 members, was adopted: That 
Article 4, Section 2. "The annvial dues shall be five dollars", be 
changed to read "The annual dues shall be eight dollars." It was 
further moved and passed that commencing January 1, 1923, 
bound volumes be charged to members at the rate of $5.00 per 
year, to non-members at $6.50 per volume, and to public libraries 
and scientific societies at $4.00 per volume. The proposed by-laws 
for the Electrodeposition Division were adopted, the result of 
the vote being 115 in favor, 1 opposed. Mr. Acheson Smith was 
appointed to represent the Society on the National Research 
Council, June 30, 1922. to June 30, 1925. Acting on a resolution 
submitted and signed by seventeen members of the Society, Dr. 
Carl Hering was unanimously elected to Honorary IMembersbip 
at the .Annual Meeting of the Board. See Volume 41. 2 (1922) 



PROCEEDINGS. 13 

It was adopted that the price of our Transactions to members of 
the Faraday Society be the same as to our members. The reloca- 
tion of the Society's headquarters from Bethlehem, Pa., to 
Columbia University, New York, was adopted by a majority two- 
thirds vote of the Board of Directors. The change was accord- 
ingly made August 1, 1923. At the July Directors' Meetuig it 
was resolved that the Publication Committee hereafter be guided 
by a limit of about 400 pages per volume of the Transactions. 
In August of last year the following measure was adopted : 
That each Board of Directors of the Society prepare a tentative 
program for the two meetings of the subsequent year and that it 
appoint, not later than the fall meeting, a committee from among 
its members to carry such programs into effect, subject to the 
approval of the new Board. 

The Board approved that any person whose membership was 
suspended during the war on account of nationality, may upon 
written application to the secretary, be reinstated without election 
or payment of the initiation fee. 



SECRETARY'S ANNUAL REPORT 
To the Board of Directors of the American Electrochemical 
Society: 

Gentlemen : The Society held two General ^leetings during 
1922— one in Baltimore, Md., April 27, 28 and 29, at which the 
attendance was 125 members and 77 guests, total, 202 ; the second 
in Montreal, Que., September 21, 22 and 23, at which the regis- 
tration was 75 members and 135 guests, total 210. The Trans- 
actions of the spring meeting, the feature of which was the session 
devoted to the reading and discussion of papers on "Electric Fur- 
nace Cast Iron," include 24 papers, and those of the fall meeting, 
embodying a symposium on "Industrial Heating," 22 papers. 

The following bound Transactions of the Society have been 
mailed to the membership since the last Annual Meeting of the 

Society : 

Volume XXXIX, Atlantic City Meeting, in June, 1922. 
Volume XL, Lake Placid Meeting, in November, 1922. 
Volume XLL Baltimore Meeting, in February. 1923. 
Volume XLII, Montreal Meeting, in April, 1923. 



14 PROCEEDINGS. 

This brings the distribution of volumes up to date, the next 
volume to be issued being the one which will cover the transac- 
tions of this meeting. The edition of the above mentioned vol- 
umes of the Transactions was as follows : 

o . Copies bound r- r^ 

Copies com- • ,„„, r„, r^ ■ „r Free Copies 

N^olume No. plete bound - JXy SoC ^St'orLe ' °^ each paper 

in cloth ietysub ^^orage to authors 

XXXIX 1,650 350 250 10 

XL 1,550 350 200 10 

XLI 1,400 300 200 10 

XLII 1,400 150 200 10 



The stock of volumes on hand April 1, 1923, was as follows: 

Volume I, 66; II, 88; III, 11 ; IV, 187; V, 210; VI, 208; VII, 
167 ; VIII, 301 ; IX, 307 ; X, 242 ; XI, 262 ; XII, 252 ; XIII, 202 
XIV, Z77; XV, 345; XVI. 408; XVII, 436; XVIII, 589; XIX 
387; XX, 371 ; XXI, 429; XXII, 372; XXIII, 346; XXIV, 487 
XXV, 491 ; XXVI, 479 ; XXVII, 230 ; XXVIII, 458 ; XXIX, 96 
XXX, 421; XXXI, 87; XXXII, 322; XXXIII, 281; XXXIV 
262 ; XXXV, 4(H ; XXXVI. 523 ; XXXVII, 358 ; XXXVIII, 514 
XXXIX, 972 ; XL, 813 ; XLI, 787 ; XLII, 989. Index 1-20, 512. 

Condition of Membership of the Society in 1922. 

Members January 1, 1922 2,172 

Qualified as members in 1922 108 

2,280 



Deaths in 1922 14 

Resignations in 1922 Ill 

Dropped for non-payment of 1921 dues 194 



319 



Members, December 31, 1922 1,961 

Net decrease for calendar year 211 



PROCEEDINGS. '5 

Condition May 1, 1922. 

Members January 1, 1923 1'961 

Qualified as members to May 1, 1923 28 



Deaths ^ 



1.989 
Dropped for non-payment of 1922 dues 204 

Members, May 1, 1923 J'784 

Members, April 27, 1922 ^'^^ 

211 
Net decrease 

Financial Statement. 
The following is a statement of receipts and expenditures, as 
of December 31, 1922: 

. Receipts in 1922 

Cash Balance-January 1. 1922 ■-■•^^ 3.537.13 

Entrance Fees ■.:::;... 6.74575 

Current Dues _ 7gQ95 

Back i^"$! ••■iQ2i ■.:::■.:■.:■.:... 3,088.00 

Advance Dues, iy^.3 ^^ 

Advance Dues, 1924 355 00 

Volumes — 1921 ^ 851 02 

Volumes — 1922 1117 00 

Volumes— 1923 ;VV 79A\^c\ 

Sale of Publications— non-Members 'oficin 

Sale of Reprints ^°^-i" 

Sale of Preprints ^^Z:'J. 

Sale of Membership Certificates o-^V 

Sale of Society Pins ■•••:■-■-•••• y ■ \;- : \ 4^47 

Payment of 1920 Transactions by Faraday Society .... W^.4/ 

Subscription to Faraday Society Transactions 184.50 

Advance Subscriptions to Ten-Year Index •..••••;••• ^^'^ 

Sale of U. S. Victory Bond and other Liberty Bonds. . . 8,910.67 

Sale of Phila. Electric Bonds with accrued interest.... ^']^-f 

Interest on Liberty Bonds VA(i\ 

Interest on Philadelphia Electric Bonds ^^^-^ 

Interest on Bank Balances ^^-^V 

Miscellaneous— Refunds on Insurance, etc J^.oi 

Electrothermic Division 

Total Receipts, January 1 to December 31, 1922 34.061.27 

^ , , $37,598.40 

lotal -^1545 42 

Total Disbursements "^^'^^^ 

Cash Balance-December 31, 1922 $ 6,052.98 



1 6 PROCEEDINGS. 

EXPEXDITURES IX 1922 

Publication Expenses: 

Printing of Volume 38 $ 3,127.64 

Printing of Discussion — Volume 38 431.40 

Printing of Volume 39 3,038.94 

Printing of Discussion — Volume 39 597.26 

Printing of Volume 40 2,528.38 

Printing of Discussion — Volume 40 389.07 

Preprints for Volume 39 834.20 

Preprints for Volume 40 2.855.72 

Preprints for Volume 41 2.525.60 

Preprints for Volume 42 1,916.82 

Engraving 677.71 

Extra Reprints 312.75 

Directory of Members (1921) 1,204.46 

Printing of Discussion — Volume 41 325.22 

Constitution and By-Laws 72.50 

Printing of Discussion — Volume 42 313.68 

Total Publication Expenses $21,151.35 

Office and General Expenses: 

Secretarial Appropriation $ 3.900.00 

Office Printing 803.75 

Office Postage 16.95 

Office Expense — Stationery and Supplies 1,107.13 

Postage on Preprints and Bulletins 817.95 

Postage on Volumes 410.59 

Freight and Express on Volumes and Preprints 81.98 

Expenses of Meetings 1.017.36 

Membership Certificates 4.42 

Membership Committee 102.85 

Publication Committee 40.10 

Booth Committee 75.00 

Local Sections 235.00 

Electrothermic Division 2.75 

Electrodeposition Division 28.00 

Moving Expense (Bethlehem to New York) 112.50 

Contribution to Annual Tables of Constants 75.00 

Storage and Insurance 279.38 

Auditing and Accounting Expenses 170.26 

Total Office and General Expenses $ 9.280.97 

Total Expenditures. January 1 to December 31, 1922 $30,432.32 

Refund: 
Return of Loan (with interest) to J. W. Richards' 

Estate $ 1.018.46 

Walter Dalton, for overpayment of Dues 5.00 

Advance Subscription to Ten-Year Index 64.00 

Collection Charge on Canadian Checks .39 

$ 1.087.85 

Bad Debts Charged Off: 
J. B. Grenagle (check uncollectible) $ 25.25 

Total Disbursements $31,545.42 



PROCEEDINGS. 17 

TREASURER'S ANNUAL REPORT, 1922 

January 1, 1922, Cash Balance $ 3,537.13 

Total Receipts, 1922 34,061.27 

$37,598.40 

Total Expenditures 31,545.42 

Balance, December 31, 1922 $ 6,052.98 

Balance in Power City Bank, 12-31-22 $ 7,160.57 

Deposits not included in Bank Statement 360.85 

Balance retained as petty cash by Secretary's Office... 50.00 

7,571.42 

Less December, 1922, checks not in 1,518.44 

Balance, December 31, 1922, as above $ 6,052.98 

We have examined the above statement of accounts, receipts, 
and expenditures for the year 1922, and find the same to be 
correct. 

(Signed) H. B. Coho, 
(Signed) Harry J. WoivF, 

Auditors. 



i8 



PROCEEDINGS, 



MEMBERS AND GUESTS REGISTERED AT THE FORTY-THIRD 
GENERAL MEETING 



Franz D. Abbott 

E. G. Acheson 
Lawrence Addicks 
A. N. Anderson 
William C. Arsem 

D. K. Bachofer 
R. O. Bailey 
A. T. Baldwin 

F. M. Becket 

E. O. Benjamin 
M. H. Bennett 
Geo. M. Berry 
Edw. L. Blossom 
Wm. Blum 

W. H. Boynton 
Robert H. Buckie 
C. F. Burgess 

C. O. Burgess 
R. M. Burns 

D. C. Burroughs 
P. Caplain 

D. C. Carpenter 

F. E. Carter 
H. Casselberry 
N. K. Chaney 

G. W. Coggeshall 
H. B. Coho 

S. J. Colvin 

E. F. Cone 
H. S. Cooper 
W. M. Corse 
J. H. Critchett 
Ed. L. Crosby 
Thomas S. Curtis 
C. Dantsizen 

F. W. Davis 
Wm. Delage 
P. K. Devers 
Arthur K. Doolittle 
E. F. Doom 

J. V. N. Dorr 



Members 

Wm. Dreyfus 
W. F. Edwards 
C. H. Eldridge 
W. H. Falck 
F. F. Farnsworth 
Alex L. Feild 
Colin G. Fink 

F. A. J. FitzGerald 
J. A. Fogarty 
Oscar R. Foster 
Gay N. Freeman 
N. H. Furman 

A. J. Gailey 
Richard H. Gaines 
W. H. Gesell 
A. E. Gibbs 
C. B. Gibson 
H. W. Gillett 

G. C. Given 
J. B. Glaze 

A. Kenneth Graham 
Carl Hambuechen 
H. E. Haring 
L. O. Hart 
W. G. Harvey 
Carl Hering 
Chas. H. Herty 
A. T. Hinckley 
C. D. Hocker 
Geo. B. Hogaboom 

E. M. Honan 
A. H. Hooker 
W. G. Horsch 
L. E. Howard 
O. Hutchins 
W. C. Hyatt 
John Johnston 
Louis Jordan 

F. R. Kemmer 
E. F. Kern 

R. H. Kienle 



D. H. Killefer 
Max Knobel 

V. R. Kokatnur 

C. G. Koppitz 
W. S. Landis 
Harry R. Lee 
F. A. Lidbury 
W. T. Little 

E. A. Lof 
J. M. Lohr 
Russell Lowe 
Dorsey A. Lyon 
Paul McAllister 
J. Y. McConnell 
Robert J. McKay 
Duncan MacRae 
Chas. P. Madsen 
Paul D. V. Manning 
J. W. Marden 

A. L. Marshall 
M. W. Merrill 
H. S. Miner 
R. B. Moore 
W. C. Moore 
W. R. Mott 
Martha E. Munzer 

D. L. Ordway 
N. Petinot 

E. C. Pitman 
H. W. Forth 
R. Prefontaine 
W. J. Priestley 
O. C. Ralston 

J. W. H. Randall 
W. C. Read 
H. T Reeve 
C. H. M. Roberts 

F. W. Robinson 
C. J. Rodman 
Chas. F. Roth 

B. D. Saklatwalla 



PROCEEDINGS. 



19 



L. E. Saunders 
C. G. Schluederberg 
Louis Schneider 
J. A. Seede 
R. L. Shepard 
Acheson Smith 
W. S. Smith 
J. S. Speer 
H. N. Spicer 
A. D. Spillman 
E. C. Sprague 
Reston Stevenson 
M. E. Stewart 
Bradley Stoughton 
Haakon Styri 
Henry P. Taber 



E. Takagi 
Fioyd D. Taylor 
Hugh S. Taylor 
Sterling Temple 
C. J. Thatcher 
M. R. Thompson 

F. J. Tone 

A. E. Thurber 
L. S. Thurston 
Henry A. Tobelmann 
R. Turnbull 
F. M. Turner, Jr. 
C. H. Tyler 
M. A. Ulbrich 
Mary Upshur Von 
Isakovics 



L. D. Vorce 
Frank J. Vosburgh 

E. A. Vuilleumier 
Helen Gillette Weir 
C. J. Wernlund 

A. E. R. Westman 
Clyde E. Williams 
Roger Williams 
A. M. Williamson 
Charles Wirt 
W. A. Wissler 
Wm. J. Wooldridge 
L. T. Work 

F. Zimmerman 



Guests 

Mrs. E. G. Acheson, New York 

City 
Robert Aiken, Washington. D. C. 
Jerome Alexander, New York City 
H. A. Anderson, New York City 
R. W. Baldwin, Milwaukee, Wis. 
Mrs. E. O. Benjamin,. Newark, 

N. J. 
P. H. Brace, Pittsburgh, Pa. 
Robert E. Brown, New York City 
R. C. Burner, Bayside, N. Y. 
Joseph T. Butterfield, New York 

City 
Mrs. Fred E. Carter, Newark, 

N. J. 
Mrs. G. W. Childs, New York City 
W. H. Coy, New York City 
Helen E. Bailing, New York City 
Edmund S. Davenport, Bloomfield, 

N. J. 
A. W. Davison, Troy, N. Y. 
Mrs. Maude T. Doolittle, New 

York City 
R. W. Erwin, Flushing, L. I., 

N. Y. 
Mrs. Colin G. Fink, Yonkers, N. Y. 
Charles FitzGerald, Malba, L. I., 

N. Y. 
Mrs. F. A. J. FitzGerald, Niagara 

Falls, N. Y. 



Mrs. Oscar R. Foster, New York 
City 

Mrs. W. H. Gesell, Montclair, 
N. J. 

F. R. Glenner, New York City 
Max Greeff, East Orange, N. J. 

E. T. Gushee, Detroit, Mich. 

Mrs. Henry K. Hardon, New 
York City 

J. E. Harris, New York City 

Henry S. Haupson, New York City 

George W. Heise, Bayside, N. Y. 

R. E. Hickman, Maplewood, N. J. 

O. K. Holderman 

H. D. Holler, New York City 

Mrs. A. H. Hooker, Niagara Falls, 
N. Y. 

Mrs. W. G. Horsch, New York 
City 

G. P. Houghland, Parlin, N. J. 
H. C. Howard, Jr., Princeton, N. J. 
N. Iseki, New York City 

C. James, Durham, N. H. 

Mrs. John Johnston, New Haven, 
Conn. 

F. C. Kelley, Schenectady, N. Y. 

D. B. Keyes, New York City 
W. P. Kierman, Bloomfield, N. J. 



20 



PROCEEDINGS. 



Mrs. D. H. Killefer. Xew York 

City 
H. W. Langzettel, Westport, Conn. 
Mrs. H. W. Langzettel. Westport. 

Conn. 
H. H. Lowry, Xew York City 
W. A. Linch, New York Cit}- 
C. E. MacQuigg. Xew York Cit}- 
Wm. A. Moore, Waterbury, Conn. 
Edward G. Nellis, Xew York Cit}- 
Keizo Xishimura. Xew York City 
W. B. Xottingham, Xew York City 
K. L. Page, Boston, Mass. 
P. G. Paris, Westport, Conn. 
F. Peters, Westport, Conn. 
Mrs. F. Peters, Westport, Conn. 
J. M. Price, Xew York Citj- 
M. B. Rascovich, Xew York City 
H. C. Rentschler, Bloomfield, X. J. 
H. K. Richardson, Xewark, X. J. 
Mrs. F. W. Robinson, Maplewood, 

N. J. 
Ancel St. John, Brooklyn. X. Y. 
John R. Sheffield. Jr., Brooklvn, 

X. Y. 
George Smith, Xew York Citj- 
Mrs. C. W. Spicer. Plainfield, X. J. 



Mrs. H. X. Spicer, X'ew York Cit>- 
Mrs. E. C. Sprague, Buffalo, X. Y. 
Mrs. W. A. Stedman, Westport, 

Conn. 
T. A. Schwartz, Prince Bav, L. I., 

X. Y. 
Theodore M. Switz, East Orange, 

N. J. 
Stem Tiberg, X'ew York Cit}' 
Magnus Tigershield, Soderfors, 

Sweden 
R. J. Traill, Ottawa, Canada 
Miss Bervle Van Allen, Xew York 

City 
H. X. \'an Dansen, X'ew York City 
G. A. Vaughn, Jr., New York City 
Alois von Isakovics, Monticello, 

X. Y. 
Miss B. von Isakovics, Monticello, 

X. Y. 
W. B. Wallis, Pittsburgh, Pa. 
W. B. Williams, Xew York City 
Mrs. A. M. Williamson, Xiagara 

Falls, N. Y. 
Mrs. Charles Wirt, Philadelphia, Pa. 
J. C. Woodson. East Pittsburgh, Pa. 
Mrs. L. T. \A'ork, Yonkers, N. Y. 
L. F. Yutema, New Haven, Conn. 



The Presidential Address presented at the 

Forty-third General Meeting of the 

American Electrochemical Society. i>» 
Sew York City May 3. 1923. 



OPPORTUNITIES FOR THE AMERICAN ELECTROCHEMIST 
ABROAD 

By C. G. SCHLUEDERBERG.' 

There have appeared in the journals from time to time fairly 
complete reports on the development of electrochemistry ui 
Europe and what has been accomplished in our own country is, 
of course, a matter of general information. Visits to bouth 
America and the Far East during the past year have aftorded 
opportunity for first-hand information and personal observation, 
and it is therefore felt that a brief summary of what has been 
done in these two sections, or of what the indications are for the 
future, may help to round out our fund of information oii electro- 
chemical development and on the opportunities abroad for the 

electrochemist. 

Electrochemical or electric- furnace development on any com- 
mercially appreciable scale inherently requires large amounts of 
electric power at low cost; therefore, in considering opportunities 
for the electrochemist it is perforce necessary to give thought to 
the power resources of the locality under observation, as these 
are so intimately allied with the possibilities for the successful 
development of the industries for which the electrochemist is 

"^^InTouth America, the west coast comitries of Peru and Bolivia, 
with their large mineral wealth and mining operations extending 
back over hundreds of years to the time of the Incas, naturally 
appeal to the imagination as fertile fields for electrochemical 
activities. Copper, silver, tin, vanadium and other ores are mined 
m quantities and, in the case of the copper, refined locally to a 
high degree of purity in large smelters of the most modern type; 
the final purification by electrolysis is, however, not carried out 
on the ground, but usually at some of the large refineries m the 

1 Westinghouse Elec. & Mfg. Co., East Pittsburgh, Pa. 



22 C. G. SCHLUEDERBERG. 

vicinity of New York, the metal as shipped containing upwards 
of 96 per cent copper or copper and silver. 

In view of the fact that this metal is shipped in such a pure 
state, and that it can receive final purification in existing refineries 
close to the markets, there is at the present time no necessity for 
the investment of the additional capital which would be required 
for the building of an electrolytic plant on the ground. A decided 
change in labor or power rates of existing electrolytic refineries, 
or in market conditions, might possibly justify such an electrolytic 
plant in the future. 

Water-power, while not over-abundant on the Pacific side of 
the Andes, is available on the eastern slopes in quantities. Pres- 
ent transportation facilities to the sites of such power, as well 
as conditions inherent to the tropical climate of that region, while 
bad, cannot be considered as insuperable obstacles. Many sur- 
veys have been made and it is quite certain that power develop- 
ments will take place. 

Considerable experimental work along electrochemical lines has 
been done by one of the larger companies in Peru, with a view 
to the working out of a satisfactory process for extracting the 
silver from certain of the local complex ores, which so far it has 
not been possible to work on a commercial scale. Should the 
results of this research work prove satisfactory, it is quite likely 
that an electrochemical plant of size would be erected in the 
Cordilleras of the Peruvian Andes in the neighborhood of 
La Oroya or Cerro de Pasco. The opportunities for the electro- 
chemist in connection with the complex silver ores of Ii*eru loom 
large indeed. Undoubtedly ores of many of the other less com- 
mon metals will afford equally attractive possibilities to the 
electrochemist with enough pioneering spirit in his make-up not 
to be deterred by primitive living conditions and the discomforts 
of working at the high altitudes which surround the deposits of 
the precious metals in this country, the fabulous wealth of which 
was first revealed to the then civilized world by the indomitable 
Pizarro almost exactly 400 years ago. 

In Bolivia, renowned for its large deposits of rich tin ore as 
well as of copper, silver, and other useful and precious metals, 
electric tin reduction furnaces have been tried, but, at least up to 
the time of my visit a few months ago had failed to prove com- 



OPPORTUNITIES FOR AMERICAN ELECTROCHEMISTS. 23 

mercially successful, the cost of carbon in the form of coal 
required for reduction purposes being one of the contributing 
factors. Here again the opportunity for the electrochemist is 
great. Just as in Peru, water-power is available in the tropical 
sections of Bolivia, and the promise of large oil developments in 
the central and eastern parts offers the chance of cheap fuel for 
steam stations, so that from the standpoint of power the estab- 
lishment of electrochemical or electrothermal processes in this 
country so rich in natural resources is entirely feasible. 

Farther south along the west coast, the northern half of Chile 
is another country richly endowed with minerals, and containing 
what is probably the largest copper mine in the world, as well as 
large deposits of iron ore, saltpeter, etc., but with an almost entire 
absence of water-power or even rain, while the southern portion, 
not so richly endowed with metal-bearing ores, is blessed with an 
abundant rainfall, water-power, and coal. However, the dis- 
tances are great and present indications for long-distance electric 
power transmission not promising. In spite of this handicap, 
electrolytic refining of copper is carried out on a large scale at 
the Chile Exploration Company's copper mine in northern Chile, 
but the copper ore here is in the form of salts readily soluble, 
from the solution of which the metal can be obtained more 
readily and economically by electrolytic means than otherwise, 
in spite of the necessity of generating electricity at an oil-fired 
steam plant on the sea coast many miles distant from the mine, 
firing the boilers with oil transported by ship from Mexico and 
the transmitting of energy over high-tension lines at 110,000 
volts. Even the water for lixiviation of the ore, as well as for 
all other purposes at this mine, has to be carried for many miles 
through large pipe lines from distant mountain sources. 

The plant of this company represents the one outstanding 
electrochemical development on the west coast of South America. 
It is a monument to the American electrochemists, through whose 
efforts the many details incident to the successful development 
of a commercially successful process for the extraction of ore on 
a large-tonnage basis, not the least important of which was the 
production of an insoluble anode, have been satisfactorily 
worked out. 

Indications of oil resources near the eastern boundary of Chile, 



24 t:. G. SCHLUEDERBKRG. 

as well as further developments in long-distance power trans- 
mission, give promise of additional opportunities for the electro- 
chemist in this progressive South American republic so far- 
famed for its mineral resources. 

So much for the west coast of South America, 

In the front rank of those countries bordering on the east coast 
and readily reached by a two-day journey from Chile over the 
famous Transandine Railway is the republic of Argentina, for 
whose renowned wealth, however, cattle and cereals and not 
minerals are responsible. Argentina is almost devoid of water- 
powers of any size. Even in mineral resources she is almost 
totally lacking. It is true that near the northeastern border are the 
Falls of the Iguassu, reputed to be capable of delivering many 
hundreds of thousands of horsepower, and on the western border 
the waterfalls of the Andes, but these are so far removed from 
present centers of civilization or human activity of any kind that 
even modern electric transmission developments, using 220,000 
volts, do not indicate that it is yet advisable to attempt the har- 
nessing of these waterfalls. As a matter of fact, the Falls of the 
Iguassu, located almost at the point where Brazil, Argentina, and 
Paraguay touch, are nearer the center of industrial activities in 
Brazil than in Argentina. 

The progressive republic of Uruguay very much resembles 
Argentina both in resources and in that at the present time there 
are no electrochemical or electric furnace developments, with 
the possible exception of one or two small steel furnaces for use 
in foundries, so that in neither of these countries does any imme- 
diate opportunity exist for the electrochemist. 

Brazil, rich in mineral resources and with great quantities of 
water-power distributed over her vast area, offers much in the 
way of opportunity to the electrochemist. He will find here 
great beds of rich iron ore, immense deposits of manganese, vast 
stores of the rarer metals and elements so widely used in the 
industries, fluxes, and reducing agents in the form of charcoal 
from the rapidly maturing eucalyptus tree, and water-powers in 
abundance. These are near the sea coast and existing centers 
of civilization, many of them already developed with power lines 
extending over wide stretches of territory. 

The most important electrochemical development is that of the 



OPPORTUNITIES FOR AMERICAN ELECTROCHEMISTS. 25 

Brazilian Electrometallurgical Company at Ribeirao Preto. where 
two 30-ton electric pig-iron furnaces have been erected, together 
with two 6-ton Bessemer converters for the direct conversion of 
the hot iron ore into steel, as well as a Ludlum 6-ton electric 
steel furnace for the treatment of such steel as may be received 
from the Bessemer converters and require special doctoring in 
order to bring it up to the desired composition. In addition, there 
are rolling mills for plates and shapes, reheating furnaces, and 
the necessary auxiliaries. Recent reports from this operation 
indicate that so far the plant has worked only on scrap metal, 
with some pig iron, which is melted in the Ludlum steel furnace. 
They have rolled as much as 20 tons of round and square bars 
per day, which have been offered at prices 10 per cent below quo- 
tations on similar foreign material. Owing to the railroad not 
having been completed to the iron ore mine, no ore has yet come 
in, and hence reduction operations have not commenced. It is 
reported that the company has been able to book enough business 
to keep the plant busy for the next year or more. 

Whereas on the west coast of South America practically all 
electrochemical and electrometallurgical processes and operations 
are carried on by Americans or Europeans, on the east coast, 
as in Brazil, this work is being carried on and financed in a large 
measure by Brazilians, although even here the apparatus, of 
American or European manufacture, so far has generally been 
installed by American or European engineers. 

A second plant for the electric-cupola reduction of the local 
deposits of iron ore on a much larger scale is under active con- 
sideration in this same district, and it is reported that the rather 
large financing required is being carried out successfully and that 
steel rails will be the principal product. 

With abundant cheap power readily available from the numer- 
ous waterfalls, and plentiful deposits of iron ore of an excellent 
grade, as well as manganese and other necessary alloys and 
fluxes, and a local market for pig iron and steel products, the 
only material thing which seems to stand in the way of Brazil 
becoming a considerable producer of iron and steel products seems 
to be the question of a suitable reducing agent, such as coal or 
coke. Here it becomes necessary to substitute charcoal usually 
obtained from eucalyptus trees, which mature within five years in 



26 C. G. SCHLUEDERBERG. 

this tropical climate, and the wood of which, planted in large 
numbers, regularly serves as fuel for railways and industrial 
plants. The fact that in the electric cupola carbon is consumed 
only in proportion to the amount of ore reduced, and that it does 
not have to serve the dual purpose of both fuel and reducing 
agent, is a factor of no mean importance where only such an 
expensive form of carbon is readily obtainable. 

Outside of possibly a few electric furnaces for foundry use, 
the above summary covers electrolytic and electrothermal activi- 
ties in six of the principal countries of the South American con- 
tinent. Reports from the other countries, not visited, do not give 
any immediate encouragement to the electrochemist, but undoubt- 
edly certain of the northern countries, when further developed, 
will offer opportunities similar to those of Peru and Bolivia. 

Turning to the Far East, we find one country at least with a 
development along lines approaching our own or that of Europe — 
Japan — rich in water-powers, many of them already developed on 
a large scale, high-tension transmission lines everywhere, and 
the one idea in the minds of all her 70,000,000 people of emulating 
western civilization and making industrial progress as rapidly as 
possible, and willing to sacrifice almost every other consideration 
to this end. This assimilation of western civilization started 
not more than two generations ago, and has attained results to 
date which must command our admiration. 

The war gave an impetus to the industries of Japan as to 
those of other countries ; the ones already in existence increased 
and many others, electrochemcial and electrothermal, came into 
being. These include manufactures of soda, chlorate, carbide, 
ferro-alloys, pure pig iron, electrolytic zinc, copper, etc., along 
with others. As in other countries, some of them since the war 
had difficulty in maintaining their existence. Today general 
business in Japan, while quiet, is improving, but many of her 
electrochemical industries are working only part time or are 
shut down. 

One plant located at Odera, 150 miles north of Tokyo, almost 
on the shores of Lake Inawashiro, close to the immense power 
plants of the power company bearing the name of that lake, one 
of the first large high-tension systems in Japan was established 
in the fall of 1916. It was completed in less than six months, and 



OPPORTUNITIES FOR AMERICAN ELECTROCHEMISTS. 



27 



is devoted largely to electrolytic extraction of zinc and the produc- 
tion of ferro-alloys. 

The sulfide ore for this plant is brought from a mine some 
fifty miles distant, and after being crushed and roasted is leached 
with sulfuric acid made locally in a chamber process plant, puri- 
fied with zinc shavings, and deposited on prepared cathodes in 
cells much resembling those used in an ordinary copper refinery. 
Costs are, however, higher than for imported electrolytic zinc, in 
spite of low power and labor charges, but the purity of the 
product seems to be higher, as evidenced by the following 
analysis : 





Japanese 

Electrolytic 

Zinc 


Electrolytic Zinc 
from U. S. A. (1918) 


Zinc 


99.96721 
0.01749 
0.00319 

0.00462 
0.00749 


99.88205 


Lead 


0.075468 


Copper 


0.00796 


Iron 


0.00518 


Cadmium 


0.0O48 







The costs of the local product have, however, been consider- 
ably higher than those of the products imported. They were 
given as 230 yen for the zinc ore, which is higher on account of 
the extensive freight rates, 70 yen for electricity, 70 yen for 
labor, and 150 yen for overhead. (The yen equals approximately 
50 cents in U. S. gold). Labor in this locality is very cheap, run- 
ning from 160 yen to 180 yen (80 to 90 cents in U. S. gold) per 
day. The capacity of the plant is reported at 300 tons of zinc 
per month. 

This plant also turns out a very pure grade of pig iron made in 
an open type electric furnace, with phosphorus of 0.021 per cent, 
sulfur 0.005 per cent, and copper 0.018 per cent; ferro-silicon 
25, 50 and 75 per cent, and silicon 90 per cent ; 60 per cent f erro- 
chrome, 80 per cent ferro-manganese, 18 per cent ferro-phos- 
phorus, and cadmium of 99.5 per cent purity, obtained from the 
zinc shavings used in purifying the zinc sulfate solution in connec- 
tion with the production of electrolytic zinc. Calcium carbide is 
being manufactured in fair quantities at present ; the extensive 
fishing industries make considerable use of acetylene torches in 
night fishing and absorb an appreciable portion of this product. 



28 C, G. SCHLUEDERBERG. 

The Cottrell process is being applied and at the present time 
nitrogen fixation and fertiHzer manufacture is receiving much 
consideration. 

That Japan is determined to keep to the fore in electrochemical 
development is evidenced not only by what she has already done 
in her industries, but also by the training given her young electro- 
chemists in the various courses on electrochemistry forming part 
of the regular curriculum of her universities, by the amount of 
attention given electrochemical subjects in the local engineering 
and scientific journals, and also by the fact that of all foreign 
countries Japan is best represented in the American Electro- 
chemical Society, which numbers in its membership about 75 
Japanese members residing in Japan, as well as many others resid- 
ing in this and other countries. 

China, in spite of her 400,000,000 people and most ancient of 
civilizations, at the present time ofifers but little, if any, oppor- 
tunity to the electrochemist. Although both rich coal and iron 
deposits exist, and fairly modern blast furnaces and steel plants 
are available for turning out pig iron and finished shapes and 
rails, there has been practically no electric furnace development, 
and electrochemistry, except as applied in a few small plating 
shops and possibly in the new mint in Shanghai, is an unknown 
quantity. There is but little water-power available or developed 
throughout the vast alluvial plain forming the eastern central part, 
or Great Middle Kingdom of China. In one or two of the more 
important coast cities electric furnaces have begun to be used in 
the foundries and shops of the larger companies. At Hongkong, 
in a steel foundry, a two-ton furnace of one of the better-known 
makes has given an excellent account of itself, albeit hand regula- 
tion of electrodes by Chinese labor melting from cold scrap has 
caused considerable conversation between the central station and 
foundry managers, with instructions from the former to the latter 
to keep ofif the line during peak hours. 

Disturbed political conditions, instability of the republican form 
of government due to the absolute unpreparedness of the mass of 
the people for self-government, maintenance of separate armies by 
the various provincial governors in their endeavor to hold indi- 
vidual power, as well as a few other disturbing factors, are at 
present militating against industrial, economic, scientific, and all 



OPPORTUNITIES FOR AMERICAN ELECTR0CHEMIST5. 2g 

Other progress. This condition applies even in South China in 
the province of Yunnan, far-famed for its wealth of tin, copper, 
zinc, and other ores and water-power. The immediate prospects 
of either electrochemical or electric furnace developments in China 
are not encouraging. 

Xor in Indo-China, the northern part of which, bordering as it 
does on Yunnan, is rich in both coal and mineral deposits, are 
there any evidences of electrochemical developments having been 
undertaken by the French, although here, as in the ]\Ialay Penin- 
sula, the problem of the reduction of tin is ever present. 

Certainly the Yunnan Province of China, Northern Indo-China, 
and the Malay Peninsula offer an interesting field for the electro- 
chemist who is not afraid to go and remain abroad amid living 
conditions radically different from those existing in the United 
States. 

Philippines: What should be the outpost of American enter- 
prise and business in the Far East and what undoubtedly will be, 
provided the uncertainty regarding self-government is eliminated 
and the United States protectorate maintained for a definitely 
stated period of years, the Philippine Islands, although blessed 
with some water-power and mineral deposits and possibly with 
oil resources, so far offer practically no field for the electro- 
chemist. However, once political conditions are sufficiently 
stabilized to justify entry of big business interests on a worthwhile 
scale, there is promise for the development of many industries, in 
some of which undoubtedly electrochemistry will apply. There 
is every indication that were the United States to guarantee 
definitely that present supervision over the Philippine Islands 
would apply for a certain period of years, say thirty, fifty, or 
more, before a local government would be considered, there is no 
doubt in the minds of those most familiar with the situation that 
big business would come into the Philippines, which are so ideally 
suited for the raising of many products, and that these islands 
would become the important center of American activities in the 
Far East, which they deserve to l^e. 

SUMMARY. 

Summarizing the possibilities for electrochemical activity in 
South American and Far Eastern countries, it would seem that 



30 C. G. SCHLUEDERBERG. 

greatest immediate progress will be made in Japan, the west 
coast of South America, and Brazil. There will be perhaps more 
general research work done in Japan than elsewhere, although 
naturally the large companies operating on the west coast of 
South America will continue research along the lines pertaining 
to their particular operations. Certain countries with ample power 
but relatively few minerals, such as Japan, are especially suited 
to the conversion of the raw products of their neighbors into 
finished materials of world-wide application. The future un- 
questionably holds much in store for them. 

Unquestionably the aggressive industrial activity of Japan will 
result in the establishment of many industries throughout that 
country, in w^hich electrochemistry and the electrochemist will 
play a large part. There can be no question that the Japanese are 
alive to the possibilities of electrochemical development, and that 
their activities along this line will be just as great as the industrial 
and financial prosperity of the country will permit. However, it 
must be kept in mind that the opportunities for the electrochemist 
in Japan will loom especially large for the Japanese electro- 
chemist, while in the other countries considered it is likely that 
Americans and Europeans will predominate. 

Richly endowed, as many of these countries are, with both 
water-power and minerals, one cannot travel through them with- 
out being impressed by the tremendous possibilities for the devel- 
opment of both natural and economic resources. 

It must be remembered that things move more slowly than 
with us, and that it takes a long time for ideas to take hold and 
a still longer time for definite results to follow. The electrochem- 
ist working in these countries must be of the pioneering type and 
possessed of infinite patience and perseverance, but once progress 
is initiated along sound lines the opportunities for profit present 
themselves in far more glowing colors than is usually the case 
in our own or European countries. The way is difficult and 
progress slow, but the possibility of reward is fully commensurate 
with the efifort involved. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 3, 1923. Dr. Wm. G. Horsch 
in the Chair. 



NEWER ASPECTS OF IONIZATION PROBLEMS.' 

By Hugh S. Taylor.'-' 

Abstract. 
A resume is presented of some recent work by Born, Fajans, 
Haber and others on the problem of energy changes accompany- 
ing the conversion of some solid crystalline substances and of the 
hydrogen halides into dissolved ions. An outline is given of the 
concepts of lattice energy and of the electron affinity of halogens, 
the quantitative side of the problem receiving detailed considera- 
tion. In the latter, small modifications of the earlier calculations 
have been made whenever newer material of a more reliable 
nature seemed to be available. Some of the lines along which 
progress may be anticipated have been indicated. 



The modern electrochemist must survey with pride the back- 
ground which his predecessors in the science provided for the 
more recent advances which the examination of the physics of 
the atom and the X-ray spectra of elements and compounds have 
achieved. The concept of ions as current carriers, of the existence 
of free ions in solution, of the mobility and hydration of ions, of 
potentials due to ions and the tendency to form ions were all 
familiar to the electrochemist before the newer ideas of electronics 
were formulated, and they materially aided the rapidity with which 
the newer developments found ready acceptance. The indebted- 
ness is, however, mutual. In the light of modern ideas as to the 
structure of atoms and ions, with the aid of the quantitative rela- 
tionships which the physicist has developed between the various 
electrical states which a substance may achieve, the electrochemist 

' Manuscript received February 14, 1923. 

* Laboratory of Physical Chemistry, Princeton University, Princeton, N. J. 

31 



32 HUGH S. TAYLOR. 

can recast anew his own ideas, can seek new methods of attack on 
older problems and, mayhap, can find a clearer method of pre- 
sentation of the fundamentals of this science. 

THE CONCEPT OF LATTICE ENERGY AND ITS THERMOCHEMICAI. 

APPLICATIONS. 

The pioneer work of Lane and the Braggs on the X-ray spectra 
of elements and compounds served to focus attention on the atoms 
as the essential units of the crystal structure, even in the case of 
compounds. A cubical crystal of rock salt was shown to consist 
of alternate sodium and chlorine, in three dimensional space at 
the corners of elementary cubical units, each sodium spaced 2.81 
X 10"* cm. from its six neighboring chlorines, each chlorine simi- 
larly spaced from six sodiums. The distance between two similar 
atoms, twice the above magnitude, may be designated as the "lattice 
constant," 8. 

By a more refined X-ray analysis, Debye and Scheerer^ were 
able to show that only a fraction of this distance between atoms 
was actually occupied by the atoms, that the electrons surrounding 
the nucleus of an atom were concentrated in a relatively small 
space around the nucleus, of radius approximately one tenth that 
of the lattice constant. Further investigation by Born* revealed 
that the units of such a crystal were electrically charged, carrying 
each a single charge. The units were, in fact not atoms but the 
respective ions. 

A detailed analysis of the attraction existing between oppositely 
charged ions so situated in space and repulsion between the elec- 
trons comprising the outer shells of such ions, led to the conclu- 
sion that the attraction varies, normally, inversely as the square 
of the distances. The repulsion, however, in the case of simple 
cubic structures, such as sodium and potassium chlorides, was 
shown to vary as the inverse tenth power, or the potential of the 
repulsive force varies as the inverse ninth power of the distance 
between the ions. 

The connection between such attractive and repulsive forces on 
the one hand and the compressibility of the crystal on the other, 
established the approximate validity of the conclusions reached : 
the cohesive force of such regular crystals is purely electrical in 

»Phy-;ikal, Zeitsch. 19, 474 0918). 

« Ber. Deut. physikal. Ges.. 20, 210 (1918): Ann. Physik, (T\') 61, 87 (1920). 



NEWER ASPECTS OF IONIZATION PROBLE^IS. 33 

its origin. It should be observed that the inverse ninth power 
relations in the case of such crystals lead directly to the assump- 
tion of a cubical atom model, such as is now familiar from the 
publications of Lewis, ^ Langmuir,® and Kossel." 

On the basis of these assumptions as to attraction and repulsion, 
Born proceeded to the calculation of the electrostatic work neces- 
sary to evaporate one mol. of the crystal into free gaseous ions, 
that is to say, the work necessary to remove the ions from the 
positions they occupied in the crystal to an infinite distance from 
one another. Born found that this energ}^ was expressible by an 
equation 

Na n — 1 
A = 

S n 

where 

N is the Avogadro number, 6.06 x 10-^ 

S is the lattice constant. 

a, is a constant characteristic of the lattice type and in the case 
of the alkali halides of the cubic system = 13.94 e-. 

e =: 4.774 X 10'^^ electrostatic units, the charge of the electron. 

n r= 9 for the alkali halides with the exception of lithium salts, 
for which n = 5. 

It is to be observed that the cubical arrangement is impossible 
for the lithium ion, since it has only two electrons in the outer 
shell. Born consequently adopted at the outset the lower value 
n = 5, demanded by the Bohr electron ring system. Typical 
results obtained in this way for a variety of salts are set forth 
in the following table, in which the unit of energ}' is the kilogram 
calorie. 

Salt 

A 



LiCl 


XaCl 


KCl 


XaBr 


KBr 


Xal 


KI 


179 


182 


163 


171 


155 


158 


144 



An alternative method of stating these energy quantities is to 
regard them as the magnitude of the free energy decrease, when 
one gram molecule of the crystalline solid is formed from the 
gaseous ions. 

(Li)^ -f- (CI)- = [LiCl] -f Aj.^/^) 

= J. Am. Chem. Soc, 38, 762 (1916). 
•J. Am. Chem. Soc, 41, 868. 1543 (1919). 
'Ann. d. Phys., 49, 229 (1916). 

•Here and in following equations parentheses, ( ), refer to gaseous components, 
brackets, f 1 , to solid substances. 



34 HUGH S. TAYLOR. 

An approximate test of the accuracy of these values was at- 
tempted by Born by correlating the above energy quantities with 
the thermal magnitudes involved in a reaction of the type, 

[NaCl] + [KI] = [KCl] + [Nal] 

Fajans ^ has shown that in the case of all these halides the change 
in total energy at ordinary temperatures, U300, is approximately = 
1.003 A. For all practical purposes, therefore, the differences in 
the above magnitudes. A, will be essentially equal to the differ- 
ences of the thermal magnitudes, U. The net change in the A 
values for the above compounds can therefore be equated to the 
net heat effect of the above reaction, i. e., 

A = ANaCl + AkI ANal AkcI = 

QNaCl + QkI QNal — QkCI 

where Q values are the heats of formation of the solid salts 
from the elementary components. A brief test will show, how- 
ever, that such heat effects are small, of the order of a few 
kilogram calories, while the individual values are of the order of 
100 Cal. ; so far as the test went it was favorable to the A values 
obtained by Born. 

A more accurate test was devised by Fajans.® By substi- 
tuting the heats of solution of the several salts in very dilute 
solution for the heats of formation used by Born, the net effect 
of the several heats of solution could be equated to the net value 
of A. Thus in the reaction given above, 

[NaCl] 4- aq = Na+ + Cf -f H, 



aq 

+ 



[KI] + aq - K- + F -f H 



aq ' aq 



[KCl] + aq = K+ -f Cl"^ + H 



[Nal] -f aq = Na,; -f F^ -f H^ 

where H refers in each case to the heat of solution of the solid 
salt, to yield a very dilute solution in which it may be assumed 
all of the salt is dissociated. Now, since the net result as regards 
ionic content is the same, whether the solutions be made up from 
NaCl and KI or from KCl and Nal, it follows that 

H=:Hi-f-H2 — H3— H, = AA=rAUrrAQ 

»Ber. Deut. physikal. Ges.. 21, 542 (1919). 



NEWER ASPECTS OE IONIZATION PROBLEMS. 



35 



111 this case the results were of a higher order of accuracy, since 
the individual H values were small as compared with the Q 
values used by Born. They were known to a higher degree of 
accuracy, and hence the test yielded by the use of such figures 
was more reliable. Table I illustrates the agreement obtained in 
a large number of examples studied. 

Table I. 



Reaction 


A 


H 


KCl + LiBr = KBr + LiCl 
KCl + Lil = KI + LiCl 
KCl + NaBr = KBr + NaCl 
KCl + Nal = KI + NaCl 


+4 

+7 
+3 
+5 


+3.6 
+7.2 
+2 
+3.4 



The Concept of Heat of Hydration of Gas Ions. 
Fajans^" further pointed out that the heat of solution of such 
salts may be regarded as composed of two effects, (a) the heat 
energy required to convert the solid salt completely into free gas 
ions (i. e., the heat equivalent of the lattice energy, or U =: 
1.003A), and (b) the heat of solution of these gas ions in water. 
As is readily seen from the following equation, 

(K)^ + (CI)- = [KCl] + U 



[KCl] + aq = K;, 



4- Cl;^ + L 



(K)^ + (CI)- + aq = Klq + Cl;^ + (U +- L) 

this heat of hydration of the gaseous ions is the quantity 
(Q + L) = W. Table II gives a summary of the values 
obtained for the heat of solution W of the gaseous ions of a 
variety of salts, as compiled by Fajans from Born's lattice 
energies and available heats of solution of alkali halide salts. 



Table II. 



Salt 


WCat + An 


Salt 


WCat + An 


Salt 


Wcat + An 


LiCl 
NaCl 
KCl 
RbCl 


187 

180.5 

159 

150 


LiBr 
NaBr 
KBr 
CsCI 


178 
171 

150 

151 


Lil 
Nal 
KI 
TlCl 


168 
159 
139 
159 



1" Ber. Deut. physikal. Ges., 21, 549 (1919). 



36 



HUGH S. TAYLOR. 



A check on these results was readily obtained, since it is 
apparent that these values should be strictly additive quantities, 
dependent on the values for the individual cations and anions of 
the several salts. Thus — 

(Na)+ + (CI)- + Aq = Na+ + CF + W^^+ ^,- 

(K)+ + (CI)- + Aq = K+ + Cr + W^+ c,- 



or (Na)+ — (K)+ + Aq 



Na+ — K+ + W 

an an ' 



Na"^, cr 



W + - 



W + — W + 



Now, since Wjj^+ — ^k+ must naturally be independent of 

the anions associated with them in the salts, it follows that 

WNa+. Br- " '^K+, Br" = ^tC. 

In this way, Table III was obtained. 

Table III. 



1 Cl 


Br 


I 


Mean 


Wl- 


- Wj,^ 


+28 


+28 


+29 


+28 


WNa^ 


- Wk- 


+21.5 


+21 


+20 


+21 


WRb^ 


- Wk- 


—9 






—9 






Li 


Na 


K 




Wci- 


- WBr- 


+9 


+9.5 


+9 


+9 


Wfir- 


- Wj- 


+10 


+12 


+11 


+11 



As is evident, the differences between the heats of hydration 
of two cations or two anions are quite definite quantities, and are 
independent of the ion with which a given ion is associated. The 
additivity of heats of hydration is thus established, and the 
plausibility of the lattice energ}' calculations enhanced. 

Further Refinements in Lattice Energy Calculations and a Test 
of the More Accurate Data. 
Bom's original calculations had shown that the calculation of 
the exponent for the repulsive force, on the basis of compressi- 



NEWER ASPECTS OF IONIZATION PROBLEMS. 



37 



bility data, led to a value somewhat smaller for sodium than 
for potassium salts. For lithium a much lower exponent, n == 5, 
was used, the low value being attributed to the lack of 
cubical structure in the lithium ion. Fajans and Herzfeld," 
accordingly, have recalculated the lattice energies of a series of 
alkali halides, assuming in addition to a repulsive force varying 
as the 9th power other terms, involving the 5th and 7th powers 
when the cations and anions are of different size. The lattice 
energies so obtained are set forth in Table IV, the older values 
of Born being enclosed in parentheses. 



Table IV. 





F 


Cl 


Br 


I 


Xa 


210.4 
(220.3) 


170.0 
(181.6) 


159.7 
(171.6) 


146.7 
(158.3) 


K 


192.2 
(190.7) 


159.0 
(163) 


150.4 
(155.3) 


139.1 
(145.1) 


Rb 




154.6 
(155.5) 


146.5 
(148.7) 


135.8 
(139.5) 



The corrections throughout are greater with the sodium salts 
than with the potassium salts. The smaller value for repulsive 
force of sodium, as found by Born, receives a satisfactory 
explanation in the newer work. As before, the thermochemical 
test of these newer values can be made on the basis of additivity 
of the heats of hydration of the gas ions. Table V gives the 
results of such a test. 

Table V. 





F 


Wp- — 

Wci- 


Cl 


Wcr — 
Wsr- 


Br 
159.5 


Wer- — 
Wi 


I 


Na . . . 




209.8 


41.3 


168.5 


9.0 


11.6 


147.9 


WNa + 


— Wk+ 


14.0 




13.9 




142 




13.9 


K .... 




195.8 


41.2 


154.6 


9.3 


145.3 


11.3 


134.0 


Wk+ 


- WRb + 


. . • • 


.... 


4.8 


.... 








Rb .. 




.... 




149.8 


.... 











I'Z. Physik. 2, 309 (1920;. 



38 HUGH S. TAYLOR. 

The means of the several differences may be therefore ex- 
pressed thus — 

W^^. - Wk+ = 14.0 Wp- — Wcr = 41.2 

Wk+ - WRb+ = 4.8 Wcr - Wer- = 9.1 

Wer - Wj- = 11.4 

Agreement within 1 Cal. is obtained in each case. The values 
obtained by Fajans and Herzfeld by this refined calculation are, 
however, regarded by Born and Gerlach^- as somewhat too low. 
Before their reasoning can be adduced, we must apply the con- 
cept of lattice energy to the determination of the electron affinity 
of halogen atoms. Before passing to this problem, however, we 
may indicate an alternative method, independent of the lattice 
theory, of testing the values obtained for the differences of the 
heats of hydration of the various gas ions. The method is due to 
Fajans^^ and makes use of various thermochemical data, the ioniza- 
tion potentials, heats of sublimation and of dissociation, respec- 
tively of potassium and hydrogen, in a determination of the heat 
hydration difference W ~ — Wk+. The method is in 
reality the application of Hess' law of constant heat summation, 
employed with the aid of the following equations: 

[K] + Aq = K- -r OH;^ -f >^(H,) + 48.1 (1) 

H:, + OH-^ - Aq + 13.6 (2) 

whence 

[K] -I- H;^ = K^^ + >^(H2) + 62 Cal. (3) 

now 

(K) = [K] -I- 21 (4) 

(K^) -f == (K) -f 99. (5) 

>^(Ho) = (H) - 45. (6) 

(H) = (H") + 0-312 (7) 

Whence by addition, (3) + (4) -f (5) -f (6) + (7) 

(K-) 4- H:^ = (H+) + K;^ - 175 Cal. (8) 

or since 

(H+) + Aq = H- + Wj,. 



aq 



«Z. Physik, 5, 435 (1921). 

'= Eer. Deut. physikal, Ges., 20, 712 (1918). 



NEWER ASPECTS OF IONIZATION PROBLEMS. 39 

and 

(K+) + Aq = K; + W^+ 

the equation (8) may be written 

Wjj+ — Wg-+ = 175 Cal. 

Equations (1) and (2) are the ordinary thermochemical equa- 
tions. Equation (4) represents the heat of subHmation of 
potassium, (5) the ionization potential of gaseous potassium. 
Equation (6) gives the heat of dissociation of hydrogen and (7) 
the ionization potential of atomic hydrogen. All these several 
quantities may be experimentally determined, though the order 
of accuracy is not as yet high in the case of several. Nevertheless 
the calculation goes to show a pronounced energy difference 
between the heat of hydration of gaseous hydrogen ions, and 
that of the gaseous potassium ion. We shall return to a dis- 
cussion of this magnitude at a later stage. In a similar manner 
and similarly independent of the concept and calculations of 
lattice energy Fajans and Sachtleben^* obtained 



and 



WNa+ — Wk+ = 16 ± 4 Cal. 



Wk+ — WRb+ = 6 ± 4 Cal. 



These values stand in good agreement with those noted previously 
as derived from lattice energy calculations. These latter there- 
fore may be given a reasonable measure of confidence. 

THE CONCEPT OF ELECTRON AFFINITY AND ITS MEASUREMENT. 

Theories of atomic structure have familiarized us recently with 
the tendency of atoms to approach the rare gas type of structure, 
by the loss or gain of an electron. The energy changes involved 
have been less prominently put forward. The loss of a valence 
electron by a sodium atom, yields a sodium ion whose outer 
system of electrons is that of the neon atom. This loss of an 
electron is, however, an energy consuming process, the energy 
involved being given by the ionizing potential of sodium vapor, 
or 5.1 volts, equivalent to a heat energy input of 118 Cal. per 
gram atom of sodium vapor. 

"Cited by Fajans, Z. Physik. 2, 328 (1920). 



40 HUGH S. TAYLOR. 

In a similar manner, potassium reverts to the argon type with 
an energy expenditure of 4.3 volts or a heat equivalent of 99.6 
Cal. At the other end of the groups in the periodic system the 
halogen atoms display a tendency to add an electron and assume 
the rare gas type of structure, a chloride ion being similar to 
argon, bromide ion to krypton, iodide ion to xenon, fluoride ion 
to neon. \\^hat the energy change involved in such a process is, 
whether positive or negative, are questions to which no direct 
method of determination has as yet been able to provide an answer. 
Several indirect methods, however, serve to show that the affinity 
of a chlorine atom for an electron is positive, that energy is 
yielded in the process of formation of a negative halide ion from 
a neutral halogen atom, or conversely that energy is expended 
in removing an electron from a halide ion. 

Born^^ and Fajans^** have indicated one method of solution of 
the problem, making use of the lattice energy calculations previ- 
ously considered. The magnitude of the electron affinity of 
chlorine atoms for electrons may be deduced by the consider- 
ation of two methods, whereby solid potassium chloride may be 
converted into free gaseous ions, potassium and chloride ions. 
The one way obviously is that involving the lattice energy previ- 
ously discussed. Let us assume Bom's first calculation of this 
magnitude, 163 Cal. The alternative method consists in decom- 
posing the solid salt into its electrically neutral constituents, 
metallic potassium and gaseous molecular chlorine, whereby 106 
Cal. are absorbed, equal to the heat produced when solid potas- 
sium chloride is produced from its elements. 

To obtain the gaseous ions from the elements it is further 
necessary to vaporize the metal, the heat absorbed being 21 Cal., 
and to ionize the vapor whereby as we have already seen a further 
99 Cal. are required. Similarly the molecular chlorine must be 
dissociated into atoms, the heat absorbed being 31 Cal. per gram 
atom, and then each of the chlorine atoms attaches itself to one 
of the electrons set free by ionization of the potassium vapor. 
This last step involves the unknown electron affinity, E, of the 
halogen atom. Since, however, we have arrived at the same end 
point by two independent paths this unknown quantity E can be 

"Ber. Deut. physikal. Ges. 21, 679 (1919). 
"Ibid., 21, 714 (1919J. 



NEWER ASPECTS OF IONIZATION PROBLEMS. 



41 



obtained by equating the energy quantities involved in the two 
steps, 

(_163) = (-106) + (-21) + (-99) + (-31) + E 

whence E = 94 Cal. 

The method of calculation of the electron affinities of bromine 
and iodine atoms may be similarly deduced as Table VI shows. 

Table VI. 



[KX] = (K ) -^ (X-) 

[K] + 54(XO = [KX] 

(X) = H(XO 

(K) = [K] 

(K^) - = (K) 

whence 

(X) + = (X-) 



CI 



—163 

+106 
+31 
+21 
+99 

+94 



—155 
+99 
+23 
+21 
+99 

+87 



—144 

+87 
+18 

+21 
+99 

+81 



Note: — The first line of the table gives Born's original values for lat- 
tice energies. The newer data of Fajans would reduce these from 4 to 
6 units. The second line gives the normal heats of reaction, probably with 
an accuracy of ^ per cent. The third line gives the heats of dissociation 
of the halogens. These are less certain. The value chosen by the writer 
for CI2 is a mean of two recent determinations (Trautz Z. anorg. Chem., 
122, 81, (1922), Q = 70 Cal. per mol. ; Henglein, Z. anorg. Chem., 123, 
137, (1922), Q = 54 Cal.) The mean 62 Cal., is concordant with the 
value calculated by Trautz from the absorption band of chlorine. See, 
however, V. Halban and Siedentopf, Z. physik. Chem., 103, 85, (1922), 
who dispute the existence of such a band. The bromine value is due to 
Bodenstein, Z. Elektrochem. 22, 317. (1916). The iodine value is from 
Starck and Bodenstein, Z. Elektrochem., 16. 961, (1910). The fourth 
and fifth lines are respectively the heat of vaporization and the ionization 
potential of potassium. 



Born and Fajans both tested their calculations by a method, 
independent of the lattice energy concept, based on the ionization 
potentials of the hydrogen halides. Born assumed that HCl 
ionizes to give H* + CI,' an assumption later confirmed experi- 
mentally by Foote and Mohler,^^ who determined the ionization 
potential Juci^o be approximately 14.0 volts. The method of 

IT J. .^m. Chem. Soc. 42, 1832 (1920). 

4 



42 HUGH S. TAYLOR. 

deriving the electron affinity of the halogen is conveniently dem- 
onstrated by the following diagrammatic outline due to Haber/^ 



(HCl) < 

>^ Qhci 


(H), (CI) 

A 




Jhci 




Jh 


)+, 


Ecl 
(C1-) < 


(H+), (■ 


-). (CI) 



(H) 

The direction of the arrows corresponds with the evolution of 
heat. Similar diagrams may be set up for hydrogen bromide, 
hydrogen iodide and hydrogen cyanide. Now Qhcp which is 
the heat of formation of hydrogen chloride from hydrogen 
and chlorine atoms, also involves the heats of dissociation of 
corresponding molecules. For the halogens we shall use the 
values previously given. For hydrogen we shall use the mean 
of Langmuir's value and that of Herzfeld/^ namely 90 Cal. per 
mol. For the ionization of hydrogen atoms the generally accepted 
value is 310 Cal. per gram atom or 13.4 volts. For the ionization 
potentials of the halides we shall use the measurements of P. 
Knipping,-° as amended recently by Franck-^ and Grimm.^^ The 
several relationships may be expressed in the following equations : 

5^(H,) + 'AiCl) = (HCl) + 22 Cal. 

(H) = y^ (H,) + 45 

(CI) = y^ (CU) -f 31 

(HCl) = (H^ + (Cr) — 313 

H* + = (H) + 310 

Whence, by summation (CI) -|- = (Cf) + Eci 

Where E^, r:r 22 -f 45 + 31 — 313 + 310 
or Eci := 95 Cal. 

This value is in good agreement with that for E^,j obtained 
from the lattice energy calculations of Born. The errors of the 

" Ber. Deut. pliysikal. Ges., 21, 754 (1919). 

i»Z. Elektrochem. 25, 302 (1919). 

WZ. Physik. 7, 328 (1921). 

"Z. Physik. 11, 155 (1922). 

»Z. phys. Chem. 102, 504 (1922). 



NEWER ASPECTS OF IONIZATION PROBLEMS. 



43 



above data are therefore of the same order as the uncertainties 
of the lattice energy data. Similarly 

Eg, = 12.1 + 45+23 — 300 +310 = 90 Cal. 
Ei = 1.5 +45 +18 — 290.5 + 310 = 84 Cal. 

The accuracy of these determinations amounts to ± 10 Cal. 
since there is an uncertainty in the ionization potential data, esti- 
mated by Knipping at ± 7 Cal., uncertainty in the dissociation 
values for hydrogen and chlorine, which may easily amount to rt 
3 Cal. Nevertheless, both the lattice energy calculations and 
those based on ionization potentials serve to show the affinity of 
halogen atoms for electrons is a large positive quantity. 

Fajans'-'"' has shown that the evaluation of this electron affinity 
for various gases has a definite utility, in indicating the probable 
effect of electron impacts with molecules of the various gases. 
Thus in the case of the halogens, the quantitative data already 
given lead to the following equations. 



(X,) = (X) + (X) 

(X) + = fx-) 

whence (X,) + = (X) + (X") 

similarly (X.) = 2(X) 

2X + 20 :- 2(X-) 

whence (XJ + 20 = 2(X-) 



CI 


Br 


—62 


-^16 i 


+95 


+88 


^33 


+42 


—62 


—46 1 


+190 


+176 : 


+138 


+130 j 



—36 Cal. 

+82 Cal. 

+46 Cal. 

—36 
+164 
+128 



It is evident therefore that the production either of atom plus 
ion or two ions by collision of electrons with chlorine molecules 
are both strongly exothermic processes. The collision of a slow 
moving electron with a chlorine molecule will therefore probably 
give a negative ion and a neutral atom in the sense of the first 
set of equations. If two electrons collide simultaneously, two 
halogen ions will result, with still larger evolution of heat. The 
affinity of halogen atoms for electrons is large enough to split the 
atomic linkage in the molecule. The existence of negative halogen 
molecules is therefore not probable. 

One further method of measurement of electron affinity has 

"Ber. Deut. physikal. Ges., 21, 724 (1919). 



44- HUGH S. TAYLOR. 

been suggested by Franck-* in a very suggestive paper connect- 
ing affinity with spectroscopic phenomena. This is not the place 
to ampHfy the subject. Interested readers may be referred to its 
treatment in the recent monograph by Foote and Mohler/^ where 
additional details on all three methods of computation may be 
obtained. The most recent spectroscopic data give-^ for E^,, , 
89.3 Cal., Eg^ = 67.5 Cal. and for Ej, 59.2 Cal., values therefore 
somewhat lower than in the preceding. 

Electrode Processes and the Newer Concepts. 

The importance attaching to the heats of hydration of individual 
gas ions prompts a closer inquiry into the determination of these 
quantities. Only one method of obtaining these seems to have 
been indicated in the literature. This method is based on the 
value for the absolute potentials of electrodes. The commonly 
accepted value for the single potential of the normal calomel 
electrode is -}- 0.56 volt. This value is based on measurements 
involving the dropping mercury electrode. Estimates of the 
accuracy of this value vary widely. By some it is regarded as 
accurate to within a few hundredths of a volt. Others,-^ however, 
claim a much greater error than this amounting to some tenths 
of a volt. 

Ostwald, accepting the higher accuracy of the value 0.56 volt 
has shown-^ that with the use of this value the heats of ionization 
of various elements may be determined approximately. With the 
aid of the equation 

d TT 



nF TT — U = nFT 



dt 



using for tt the value for the single potential of a given electrode 

(Jtt 

and for its temperature coefficient, Ostwald and Jahn-" 

determined U for a number of elementary electrode processes. 

"Z. Physik. 5, 428 (1921). 

** The Origin of Spectra, A. C. S. Monograph Series, Chera". Catalog Company. 
1922, Chap. VIII. 

"Angerer, Z. Physik. 11, 169 (1922). 

»^Cf. Garrison, J. Am. Chem. Soc., 45, 37 (1923). 

i»Z. physikal Chem., 11. 506 (1893). 

29 Z. physikal. Chem., 18, 421 (1895). 



NEWER ASPECTS OF IONIZATION PROBLEMS. .45 

M =^ W 

aq 

For the reaction at the hydrogen electrode 

(H^j pt - h:^, 

the heat of reaction was shown to be very small, and of the 
order of ± 1 Cal. An error of 0.25 volt in the determination 
of the absolute potential would involve a corresponding varia- 
tion of 0.25 X 23 = ±6 Cal. in this value for the electrode pro- 
cess, which is not a higher order of error than is inherent in the 
calculations recorded in earlier sections of this paper. Accepting 
Ostwald's value for the hydrogen electrode process, Fajans has 
associated it with the material accumulated by him with reference 
to the combined heats of hydration of cation and anion. The con- 
version of molecular hydrogen to hydrogen ions in solution takes 
place in a cell in which the gas is bubbled over a platinum elec- 
trode. The hydrogen ions pass into the solution, the electrons 
remain on the platinum side of the double layer at the junction of 
electrode and electrolyte. The net heat change of this electrode 
process, ± 1 Cal. is composite of two thermal magnitudes, that 
of the change from molecular hydrogen to dissolved hydrogen 
ions and that associated with the presence of electrons in the 
platinum metal. This latter is equal and opposite to the energy 
required to evaporate electrons from the metal, a quantity which 
amounts, according to Born,-^" to approximately 100 Cal.'' 

We may therefore obtain the heat of hydration of gaseous 
hydrogen ions assuming this value by the following set of 
equations : 

(H^) -f = (H) + 312 Cal. 

(H) = ^ (HJ + 45 Cal. 

(H3) -f Pt 4- aq = h;^ + Pt(-) + Cal. 

Ft (— ) = Ft + — 100 Cal. 

Hence, by addition (H+) + Aq ^H^^ + 257 Cal. 
Now, as was shown in an earlier section 



Wjj, - Wj,, = 175 Cal. 



*• Loc. cit. 



3' Most varied values are to be found in the literature for this magnitude varying 
between 2.5 volts for platinum containing hydrogen to 6.6 volts (Langmuir) in which 
special precautions were taken to ensure the absence of this gas. No high order of 
accuracy can therefore be assigned to this quantity. 



46. HUGH S. TAYLOR. 



Hence it follows that 




Wk. 


= 257 — 175 = 82 Cal, 


And, since 






Wg. + W^i- = 159 




Wj,,- = 77 Cal. 



On the basis of such a procedure Born'- has compiled the 
following table of individual heats of hydration of gas ions. 



H- 


Li^ 


Na^ 


K* 


Rb^ 


Cs- 


CI- 


Br 


r 


262 


110 


103 


82 


71 


74 


77 


68 


57 



The hydrogen value in this table is slightly different from that 
given above due to small variations in the values used for the heat 
of dissociation of molecular hydrogen. Especially noteworthy is 
the decrease in value for the heat of hydration with increase in 
the size of the ion. 

It is apposite at this point to define more precisely the signifi- 
cance of the concept of hydration of gas ions. According to 
Fajans it is not to be regarded as involving the solution of a 
gaseous ion in the water with the formation of ion-hydrates of 
definite stoicheiometric composition. Rather has one to assume 
that, through the charge which the ion carried, the oppositely 
charged parts of the polar water molecules in its immediate 
neighborhood are oriented towards the ion, whereas the similarly 
charged portions of the water molecules are turned away from 
the ion, and, in their turn, act electrically upon the molecules in 
their immediate environment. There results, therefore, a kind of 
electric polarization in the solution. In the preceding table there 
is obviously a greater heat of hydration the smaller the gas ion. 
The electrical forces are operating at smaller distances. Born 
concludes that in every case, irrespective of the nature of the gas 
ion the heat of hydration of the gas ion will be a positive quantity. 

In the preceding calculation of the individual value for the 
heat of hydration of the hydrogen gas ion, it is apparent that the 
calculation involves the magnitude of the heat change associated 
with the electron emission from the metal used as the 
hydrogen gas electrode, which was platinum in the example 

^- Loc. cit. 



NEWER ASPECTS OF IONIZATION PROBLEMS. 47 

considered. It was pointed out that a considerable degree of 
uncertainty attaches to this value. It would therefore be well 
worthy of experimental investigation how or whether the char- 
acteristics of the hydrogen electrode change, as a consequence of 
alteration in the metal used as electrode material. Of many sub- 
stitutes considered, tantalum appears to us to offer possibilities of 
usefulness. It is known to take up many times its own value of 
hydrogen. Furthermore, its thermionic emission has been most 
carefully studied. The data for an independent check on the 
magnitude of the individual heats of hydration should therefore 
be easily obtained. We plan to obtain these if possible. 

Meanwhile we must regard the data already given in the pre- 
ceding table as tentative. The corresponding calculation for a 
potassium electrode does not yield the same value for W^.^. as is 
obtained indirectly from the above calculations, as the following 
equations demonstrate. 



[K] 


= (K) - 21 


(K) 


= (KO -f e - 99 


(K^) 


+ Aq = K;^ -f W^. 





-t- K = K(— ) + 50.6 



Now we have shown (p. 290) that 



And since 



[K] -F h;^ = k;^ + y,(K,) + ez 



Hia = V2 (H,) + Aq + 



it follows that the electrode process potassium — K* or alter- 
natively 2 [K] = k;^ + K (— ) + 62 Cal. This would yield 
for Wg^ a value ^132 Cal., deviating most markedly from that 
given by the hydrogen calculation. The diversity between the 
two has its origin in the two equations 

Pt + e = Pt (— ) -f 100 
and 

K + = K (— ) + 50.6 

This latter is the most probable value from determinations of the 
photoelectric effect, and seems equally as well founded as the 
platinum value used by Born and Fajans. 



48 DISCUSSION. 

It is evident, therefore, that the problem is only in its initial 
stages. Much work remains to be done, much progress to be 
made. In the present communication, the argument has been 
confined solely to the hydrogen and alkali halides, because with 
the aid of direct measurements of ionization potentials of the 
hydrogen halideS, and with the readily verified calculations of lat- 
tice energy, for the relatively simple alkali halide crystal lattices 
a surer basis for calculations existed. The treatment is being 
extended to other compounds, as a recent attempt by Grimm^' 
indicates. There opens up a new field of investigative work which 
cannot fail to have its influence on the development of electio- 
chemical science in general. 



DISCUSSION. 



vS. C. LiND^ : Prof, Taylor's paper is extremely interesting. I 
had frequently been tempted to undertake a similar analysis to 
that of Prof. Taylor, and therefore it interests me all the more. 
At the time that many of us became members of the Society, we 
were entirely satisfied with the electrolytic pressure theory, or the 
Nernst theory, of what happens at an electrode. It has been 
evident to many of us for some time that it would be extremely 
important to study electrode phenomena from the standpoint of 
gaseous ionization. One of the difficulties has been to know 
whether the elctrolytic ion is exactly the same as the gaseous 
ion ; and that is one of the assumptions Prof. Taylor has had to 
make, about which there might possibly be some question. 

It will be useful in the future to use these conceptions that Prof. 
Taylor has brought to our attention, whether they ultimately 
prove to be correct or not. 

John Johnston^: I would like to support the idea Dr. Taylor 
is emphasizing, namely, that the usual picture of the process of 
ionization in solution is not satisfactory, and that, so far as I 
know, no one has outlined a satisfactory picture of the process of 
forming an ion at the electrode in solution. 

"Z. physikal. Chem., 102, 113 and 504 (1922). 

' Chief Chemist, U. S. Bureau of Mines, Washington, D. C. 

' Yale University, New Haven, Conn. 



NEWER ASPECTS OF IONIZATION PROBLEMS. 49 

S. C. LiND : Those of us who have believed for a long time that 
gaseous ions might be chemically active have met opposition on 
the part of physicists, who have pointed out that in the case of the 
electrolytic ions, the sodium ion and the chlorine ion, we have a 
special case. That, for example, in the case of the sodium ion with 
one positive charge, and the chlorine ion with one negative charge, 
under the Lewis- Langmuir theory leads to the rare gas configura- 
tion, which we all admit to be inert. In other words, if the as- 
sumed electrolytic sodium ion were present as a gaseous ion, you 
would not expect it to be chemically active, except through an 
electrical attraction for the electrical opposite. Therefore, if that 
is true, we would not expect the sodium ion with one negative 
charge to be active toward electrically neutral water, nor would 
we expect it to lead to a reaction with high heat of reaction. I 
merely want to ask Prof, Taylor what explanation he would give 
of that objection of the physicist. It is not one that I am raising 
at all, but one that has been raised to theories that I hold. 

H. S. Taylor : I do not know what the answer to such an ob- 
jection is. The chlorine ion is certainly a peculiarly stable system. 
At one time I (along with Dr. Lind and some others who had been 
working in the field before) thought that if I could succeed in 
getting the chlorine ion in a hydrogen chlorine mixture I could get 
a reaction. In view of what has accumulated with regard to the 
nature of chlorine ion, I myself am skeptical now. I would agree 
with the physicist in saying that the chlorine ion is something 
akin to a noble gas, except in so far as you have an excess nega- 
tive charge, and thereby can have electrical attraction such as is 
present in solid sodium chloride. This is one of the problems 
that certainly needs the intense co-operation of the physicist and 
the electrochemist. 

W. C. Moore' : A number of years ago I was interested in 
gaseous conduction, particularly with reference to the flaming arc. 
I looked up the literature on the subject and found that Prof. H. 
A. Wilson, who at that time was doing considerable work on con- 
duction in gas flames, had discovered that potassium ion in po- 
tassium chloride vapor carried three positive charges ; whereas, 

* Research Chemist, U. S. Industrial Alcohol Co., Baltimore, Md. 

5 



50 DISCUSSION. 

we suppose we know that it carries one charge only, in solutions 
in water. 

There is an interesting discrepancy here ; we need some means 
of determining how the number of charges on a potassium ion 
vary in raising the temperature from that of a bunsen burner to 
that of the flaming arc. 

H. C. Howard* : The same objection could be urged against 
the activity of the electrolytic potassium ion, because that also 
reverts to the rare gas type. 

S. C. Lind: It is correct that many of the electrolytic ions 
follow a special class, and fall into the rare gas series. On the 
other hand, it does not follow that we can not have some kind of 
a chlorine negative ion as, for instance, CI 2, with one negative 
charge, which will not fall into that class. We have in the 
gaseous ions a much wider variety in nature than in electrolytic 
ones, and we should not be hasty to conclude that there is no such 
thing as a chemically active gaseous ion. 

H. S. Taylor : The little section on page 43 tends to show that 
the existence of negative halogen molecules is not probable. I 
think the evidence on that point is fairly conclusive, since the 
magnitudes of the heat quantities involved are so tremendously 
large. 

* Princeton, N. J. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in Nezv York 
City, May 3, 1923, Dr. Wm. G. Horsch 
in the Chair. 



OXYGEN OVERVOLTAGE OF ARTIFICIAL MAGNETITE IN 
CHLORATE SOLUTIONS.' 

By H. C. Howard." 

Abstract. 

Attempts were made to oxidize sodium chlorate to perchlorate 
electrolytically at a magnetite anode. Negative results were 
obtained. The oxygen overvoltage of a magnetite anode in N 
sodium chlorate was measured and found to be from 0.4 to 0.6 
volt lower than that of smooth platinum. 



Several years ago, in the course of a study of the electrolytic 
oxidation of sodium chlorate to perchlorate, some time was 
devoted to an attempt to find a substitute for the expensive 
platinum anodes usually employed. 

All of the common and many of the rarer metals were tried 
and all, except those of the platinum group, were found to 
corrode very rapidly when used as anodes in a sodium chlorate 
electrolyte. Carborundum and the various high silicon alloys 
were shown to be valueless and the oxide electrodes, such as 
lead peroxide and manganese dioxide, which have been used 
effectively as insoluble anodes in certain cases, decomposed very 
quickly under the conditions present in this electrolysis. 

It was known that an artificial magnetite had been used with 
success in some of the German alkali-chlorine cells, and we were 
anxious to test this material. Finally we obtained samples of 
such electrodes, through the courtesy of the Chile Exploration 
Co. These artificial magnetite electrodes proved to be very 

' Manuscript received February 2, 1923. 

^ Contribution from the Chemical Laboratory of Princeton University. 

51 



52 



H. C. HOWARD. 



resistant to corrosion, and in this respect appeared to offer a good 
substitute for platinum. Analysis of the electrode in which these 
anodes had been tested showed, however, that no perchlorate had 
been formed during the electrolysis, and this was found to be the 
case in all later experiments, even under the most favorable con- 
ditions for perchlorate formation, such as low temperature and 
high current density. 

At the time, this was explained by assuming that the over- 
voltage of oxygen at magnetite is very much lower than at smooth 

Table I. 
Oxygen Overvoltage of Magnetite in Sodium Chlorate. 

Electrolj'te, N sodium chlorate. Temperature, 20° C. Area of the anode 

was 36 sq. mm. in each case. The potentials are referred to 

-V calomel electrode as zero, and are all positive. 



Smooth P] 


atinum Anode 




Magnetite Anode 










anode 




c. d. 
amp./sq. dm. 


potential 

V. 


c. d. 
amp./sq. dm. 


potential 

1 ^• 


magnetite 
potential* 


3.0 


2.04 


1.4 


1.58 


1.58 


S.S 


2.10 


2.8 


1.61 


1.61 


8.3 


2.17 


5.0 


i 1.66 


1.65 


11.0 


2.23 


11.0 


1 1.72 


1.69 


22.3 


2.46 


16.6 


1.79 


1.75 






22.8 


1.86 


1.80 



• Potential of the magnetite, corrected for the voltage drop in the electrode itself. 
The resistance of the electrode and contact was 0.7S ohm. The resistance of the plati- 
num electrode was negligible. 

platinum, and hence, at anodes of the former material, oxygen 
evolution takes place in preference to the oxidation of the chlorate 
ion to the perchlorate. 

A search of the literature revealed no data on the oxygen over- 
voltage of magnetite, and since lack of time prevented further 
experimental work, a test of the explanation offered was not then 
possible. 

Recently a few measurements of the oxygen overvoltage of 
magnetite in sodium chlorate have been made in this laboratory. 

The results of these measurements are presented in Table I 
and Fig. 1. 



OXYGEN OVERVOLTAGE OF MAGNETITE. 



53 



These data and curves show clearly that the oxygen overvoltage 
of magnetite is much lower than that of smooth platmum. 







;♦ .b 16 2<» ^^ 2f 



Fig. 



1. Potentials of platir.um and magnetite in N sodium chlorate. 



CONCLUSION. 

The failure to oxidize chlorates to perchlorates at a magnetite 
anode together with the fact that such an anode has been shown 
to hav'e a much lower oxygen overvoltage than a smooth platmum 
one at which such an oxidation takes place readily, afford further 
conkrmation of the hypothesis that there is a direct relationship 
between the overvoltage of an electrode and its oxidizing or 
reducing power. 

DISCUSSION. 
Colin G Fink^ : Mr. Howard's paper is interesting and brings 
up the general subject of the insoluble anode. In electrolytes such 
as we have studied, particularly with SO, ions present, a number 

1 Consulting Metallurgist, New York City. 



54 DISCUSSION. 

of reactions occur. The ultimate anode reaction is the liberation 
of oxygen gas. Now anything that will hasten the evolution of 
oxygen gas in preference to the dissolution of the metal of the 
anode, will cut down the corrosion of the anode under investiga- 
tion. In other words, you finally come to a point where you can 
use a very soluble anode, providing you have on the surface a 
thin film of a catalyzer, which will hasten the discharge of the 
SO4 ions and the formation of oxygen gas in preference to the 
formation of metal compounds. 

In other words, the overvoltage phase of the insoluble anode 
is a phase which has not always been taken into account, because 
primarily the metals have been studied from the purely chemical 
solubility point of view. 

M. KnobeL" : Regarding the relation between oxidizing or 
reducing power and overvoltage, while one can find a good many 
cases in the literature where a high overvoltage metal does give a 
greater oxidation or reduction than a low overvoltage metal, one 
can also find as many cases where this relation does not hold. 

W. G. HoRSCH" : Since Dr. Bancroft is not here, it may be 
safe to quote him as stating that oxidation at an anode may be 
linked up with high overvoltage, but is not necessarily a conse- 
quence thereof. 

I took the liberty to subtract the reversible potential of the 
calomel-oxygen cell from Mr. Howard's results and compare the 
overvoltages thus obtained with those of Dr. Knobel in the next 
paper on our program, and I get 0.3 to 0.4 of a volt difference at 
practically all points in the curve. The curves as determined by 
these two authors thus show good agreement as to shape. 

H. C. Howard: My results are referred to the calomel elec- 
trode, as zero. The potential of the calomel electrode has already 
been subtracted. Whereas, Dr. Knobel's results represent real 
overvoltages. You would obtain more nearly comparative values 
if you subtracted the reversible potential of oxygen from my 
results. 

W. G. Horsch: What I meant was platinum in terms of 
oxygen. 

* Mass. Inst, of Technology, Cambridge, Mass. 
« Chile Exploration Labs., New York City. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 3, 1923, Dr. JVm. G. Horsch 
in thi Chair. 



THE EFFECT OF CURRENT DENSITY ON OVERVOLTAGE/ 

By M. Knobel. P. Caplan, and M. Eiseman' 
INTRODUCTION. 

There are numerous references^ in the literature on the effect of 
current density on overvoltage, but they are in general more or less 
isolated values and for comparatively small current densities. 
The experimental conditions are so different also that it would be 
difficult to compile a comparable set of data. On account of the 
great technical importance of this phase of overvoltage, and also 
for the theoretical interpretation of overvoltage, it was thought 
desirable to have extensive and consistent data in this field. In 
the following work we have attempted to include all the more 
common metals and alloys as cathodes, and to determine oxygen 
and halogen overvoltages on as many electrodes as possible. 
While the overvoltage values obtained may not be acceptable as 
absolute values, they should at least be comparable as the experi- 
mental conditions were maintained the same in all cases. 

METHOD OF MEASUREMENT. 

W'e have accepted as our definition of overvoltage "the poten- 
tial necessary in excess of the reversible potential to discharge the 
product in question, both potentials being measured under identical 
conditions as external hydrogen pressure, temperature and con- 
centration of solution." Thus the hydrogen overvoltage on a lead 

' Manuscript received November 4, 1922. 

^ Contribution from the Rogers Laboratory of Physics, Electrochemical Laboratory, 
Massachusetts Institute of Technology. 

'Tafel. Z. Physik. Chem. 50, 641 (1904); Ghosh, J. Am. Cham. Soc. 36, 2333 
(1914); 37, 733 (191S); Rideal, J. Am. Chem. Soc. 42, 94 (1920); Newbery, J. Am. 
Chem. Soc. 109, 1051, 1066 (1916); Sacerdotti, Z. Elektrochem. 17, 473 (1911); 
Tainton, Trans. Am. Electrochem. Soc. 41, 389 (1922); Reichinstein, Z. Elektrochem. 
17, 85 (1911); Coehn & Osaka, Z. anorg. Chem. 34, 86-102 (1903); Foerster & 
Yamasaki, Z. Elektrochem. 16, 321 (1910); Bennewitz, Z. Physik. Chem. 72, 202 
0910); Lewis & Jackson, Z. Physik. Chem. 56, 193 (1906); Coehn & Dannenberg, Z. 
Physik. Chem. 38, 609 (1901); Gockel, Z. Physik. Chem. 32, 607 (1900); Niitton & 
Law, Trans. Far. Soc. 3, 50 (1907). 

55 



56 M. KNOBEL, P. CAPLAN, AND M. EISEMAN. 

cathode at a given current density will be the potential difference 
between that lead cathode and the solution, minus the potential 
difference between a reversible electrode (practically platinized 
platinum with no current flowing) and the same solution at the 
same temperature and pressure. We believe this to be the 
generally accepted definition. 

There are two methods of measuring overvoltage, and the ques- 
tion arises as to which gives the overvoltage just defined. The 
first is to insert a reference electrode with the tip against the 
cathode and measure the electrode potential while the current is 
flowing. The second or commutator method, which has been 
championed principally by Newbery* on the other hand, allows 
for shutting off the electrolyzing current while the electrode 
potential measurement is being made; it alternately allows the 
electrolyzing current to pass and then connects the cell to the 
potentionmeter. The main argument for use of the commutator 
is that all ohmic resistance drops are eliminated ; but let us defer 
the discussion of this point until we have analyzed the commu- 
tator method to see whether it gives correct values. 

The potential measured in the commutator method depends on 
the concentration of the electrode products stored up during the 
period of electrolysis. The curves determined by LeBlanc^ with 
an oscillograph and a commutator throw light on this point. The 
t}'pical curves obtained by him for the variation of electromotive 
force across the cell (ordinates) with time (abscissae) are shown 
in Fig. 1, 2 and 3. Fig. 1 is for the electrolysis of a normal iodine 
and potassium iodide solution between platinum electrodes ; Fig. 
2 is for 0.05N iodine and potassium iodide in one normal sul- 
furic acid, and Fig. 3 for one normal sulfuric acid. In all of 
these curves the portions A are for the time when the electrolyzing 
current is on, portions B when the current is shut off and the 
oscillograph only is connected to the cell; and portions C when 
the electrolyzing current is passing in the reverse direction. A 
difference in LeBlanc's procedure and Newbery's must be noted 
in that the electrode products must supply current to operate the 
oscillograph in LeBlanc's arrangement when the outside current 

< Trans. Far. Soc. 15 (1919") ; J. Am. Chem. Soc. 42, 2007 (1920). 
» "Die Elektromotorischen Kraitte der Polarization und ihre Messungen mit Hilfe 
Jes Oszillographen" Hall, 1910. 



EFFECT OF CURRENT DENSITY ON OVERVOLTAGE. 



57 



is shut off, while Newbery takes no current from the cell in this 
interval. 

Fig. 1 indicates that no polarization has occurred, neither in the 
nature of overvoltage nor concentration polarization in the solu- 
tion. The fact that portion B is directly on the zero potential axis 
means that the two electrodes are in the same condition, that is, 
have the same potential difference with respect to the solution, 
and the flatness of portion A shows that the electrolysis is 
occurring at constant potential. The distance of A and C from 
the axis is presumably due to ohmic resistance drop in the whole 
cell. This electrolysis is therefore reversible as far as the elec- 
trodes are concerned. 



A 


B 










B 








C 







Fig. 1 




Fig. 2 




Fig. 3 



Fig. 2 indicates the existence of some polarization due to 
accumulation of electrode products, as hydrogen and oxygen, or 
concentration differences in the electrodes. This curve is typical of 
all LeBlanc's measurements on oxidation reduction cells such 
as the ferri-ferro ion electrode, etc. The form of Fig. 3 is 
without doubt caused by the accumulation of Hg and O, on the 
electrodes. During the time represented by A the electromotive 
force gradually increases as the gas concentration increases. The 
maintenance of the potential at B has its source in the gases 
at the electrodes yielding current by going back into solution. 



eg M. KNOBEL, P. CAPLAN, AND M. EISEMAN. 

It is the electromotive force represented by B that the com- 
mutator method should measure. For the low current densities 
used by LeBlanc in his work (about 0.0045 ampere per sq. cm.) 
the commutator should give essentially correct results. If no 
current were taken from the cell during the time B, that portion 
of the curve would probably be more nearly horizontal, which 
of course it should be, to allow accurate measurement on a poten- 
tiometer, and to have a definite meaning. 

In consideration of the very small time interval (about 0.019 
second) when the electrolyzing current is on and ofif, and of the 
small current used, the gases liberated at the electrodes cannot 
attain high pressures and will not tend to diffuse away 
appreciably. They should then have essentially the same concen- 
tration as when the current is passing, and B should give the 
back electromotive force or the overvoltage (of both electrodes) 
according to the definition previously given. In support of this 
reasoning is the fact that at low current densities Newbery's 
values obtained by the commutator, are the same within the limits 
of reproducibility of overvoltage, as those obtained by the direct 
method. 

However, at high current densities and with electrodes other 
than platinum the above relations cannot hold. It is well known 
that platinum has a much greater power to occlude or adsorb 
gases than other metals. At the opposite extreme is mercury 
which probably adsorbs only extremely small quantities of gas. 
The gas accumulation at a mercury electrode must then occur in 
a laver of solution under which conditions the gas may easily be 
carried away by convection or diffusion. A curve analogous to 
Fig. 3 for mercury electrodes would show a sharp drop in the 
portion B and the overvoltage measured by the potentiometer 
would be much lower than the back electromotive force when 
the current was passing. Newbery in fact gives values for mer- 
cury overvoltage at low current densities, obtained by the commu- 
tator method, considerably lower than those obtained while the 
current is passing. 

At high current densities the stirring effect of the evolved gases 
will also cause portion B to drop sharply from its maximum. For 
large currents the gas pressure is comparatively much larger, 



EFFECT OF CURRENT DENSITY ON OVERVOLTAGE. 59 

which in itself will tend to increase the loss of gas by diffusion. 
Of probably much greater importance however is the violent 
stirring of the solution directly at the electrode surface by the 
evolved gas. Most of the gas which is in the solution, possibly 
in a super-saturated state, will be swept away so that it is no 
longer in contact with the electrode. Again this explanation is 
supported by the very low values obtained by Newbery at high 
current densities, at mercury as well as at other electrodes. 

The time interval in which this must occur is small. For the 
speed of 2,500 revolutions per minute of the commutator as used 
by Newbery the current is broken only 0.012 second, but 
LeBlanc's time interval is 0.019 second, and an appreciable drop 
has occurred in the case in Fig. 3 where the drop is least to be 
expected. Some of these points have been tested experimentally 
recently by Tartar & Keyes" and all their results directly confirm 
the conclusions drawn here. Other investigators^ have criticized 
this commutator method, but we will not attempt to discuss their 
criticisms here. We believe the method can fairly be rejected. 
The extensive tables of Newber}'^ are of little value if the objec- 
tions to the commutator method are valid. 

The question of eliminating ohmic resistance drop in the 
closed circuit method is a serious one. Obviously the reference 
electrode tip cannot be situated any large distance from the 
electrode surface, or the potential drop in the solution will be 
measured with the over voltage. One method, which unfor- 
tunately has been rather widely used in an attempt to obviate 
this difficulty®, is to place the reference electrode behind the 
cathode, that is, on the opposite side from the anode. This is 
obviously in error for the current density is indefinite and much 
smaller on the back face of the cathode and the potential so meas- 
ured bears no relation to the potential difference between the 
electrode and the solution in contact with the front face. While 
the electric potential of the whole electrode is the same, the solu- 
tion in front of and behind the electrode need by no means have 

•J. Am. Chem. Soc. 44, 557 (1922). 

• Tainton, Trans. Am. Electrochem. Soc. 41, 389 (1922); Maclnnes, T. Am. Chem. 
Soc. 42, 2233 (1920). 

«J. Chem. Soc. 109, 1051, 1066 (1916) 111, 470 (1917). 

* See for example Nutton and Law, Trans. Far. Soc. 3, SO (1917); Pring and Curzon 
Ibid. 7, 237 (1911). 



6o 



M. KNOBEL, P. CAPLAN, AND M. EISEMAN. 



the same electric potential, and therefore the potential difference 
between electrode and electrolyte will be different on the two sides. 
While seemingly unnecessary we have tested this point experi- 
mentally and confirmed the statement made. 

If the reference electrode tip is placed on the front side it dis- 
turbs the current flow lines in the small region near the tip. A 



1 to 






























1 


tea 
























^ 


^ 


^ 




















^ 


-^ 


^ 










> 
3 












,--- 


-4 


•^ 


^ 


^+"» 
1^^^ 




















!> 




^ 
















^ 






'^ 




Y^ 








^ 


■» 










S 




/" 


yy 






^ 




^^ 












V 
2.^, 


/ 


y 








^ 




















9 

1 


1 r 




/ 


y 


























1 


/ 


r 


























/ 


/ 




























1 7a 


V 






























i 






























2 76 
/•75 































































as to ;-s t-o i-& Od 

Distance from electrode surface in mm. 

Fig. 4. Showing effect of varying size of electrode tips. 



large tip or one pressed too closely to the surface would cause 
an appreciable decrease in current density in the electrolyte 
immediately between the tip and the electrode, and too low over- 
voltage values will result. It would appear that the smallest 
possible tip would be desirable. This was tested out experi- 
mentally by a series of tips of different diameters. They were 
moved up to an electrode from some distance out in the solution 



EFFECT OF CURRENT DENSITY ON OVERVOLTAGE. 6 1 

and the potential plotted as a function of the distance. As 
uniform a current density as possible of 0.5 ampere per square 
centimeter was maintained. 

An auxiliary reference electrode held at a constant position 
with respect to the lead cathode used, indicated the constancy 
of the latter. The results are shown in Fig. 4. The ordinate 
scale is the electrode potential in volts with an arbitrary zero. 
The abscissae indicate the distance of the tip from the electrode 
surface, measured in mm. The tip sizes corresponding to the 
numbers on the curves are as follows: — No. 1, 4.6 mm. in 
diameter ; No. 2, 3.1 ; No. 3, 2.3 ; No. 4, 1.3 ; No. 5, 0.08. The slope 
of the curves is of course due to the resistance of the electrolyte. 
For the larger tips the drop in potential in excess of the ohmic 
resistance drop, as the tip approaches the electrode, is marked. 
The use of a tip as large as the first, pressed against the electrode 
would introduce an error as large as 0.04. If the tip is one milli- 
meter or less in diameter, however, we concluded it would give 
essentially correct values practically independent of the tip 
diameter. 

Another experiment with a mercury cathode proves conclu- 
sively the lowering of the potential measured by the lowering of 
the current density in the above manner. The tip was lowered 
from a point out in the solution until it was some distance under 
the mercury surface. The electrode potential decreased at a 
constant rate, due to the change in the ohmic resistance in the 
electrolyte until the tip had made a slight depression in the 
mercury. When the tip was pushed still further into the mer- 
cury, the electrode potential dropped very quickly to a value not 
far from the hydrogen electrode potential, and was not influenced 
at all by changes in the current density on the remainder of the 
mercury surface. A small electrode tip was also pushed into soft 
lead sufficiently to cause a marked lowering in potential. 

We therefore have used tips of approximately one millimeter or 
less in diameter and have pressed them directly but lightly against 
the active electrode surface during measurements. A small piece 
of cotton is inserted in the end of the tip to prevent bubbles enter- 
ing the tube and breaking the electrical circuit. 



62 M. KNOBEL, P. CAPLAN, AND M. EISEMAN 

APPARATUS. 

The electrolyzing vessel was a U-tube of 3.8 cm. (1.5 in.) 
tubing, the anode and cathode being in opposite arms, and the 
cross tube plugged with cotton wool to prevent mixing of the 
solutions. The electrode under investigation was placed directly 
opposite the cross arm and was sufficiently small (usually one 
centimeter square) so that a uniform current density was 
obtained. Three ammeters of dififerent ranges were placed in the 
electrolyzing current line to measure accurately small and large 
currents. The potential measuring apparatus was an ordinary 
potentiometer sensitive to 0.1 millivolt. The reference electrodes 
used were Hg, HgoSO^, H2SO4 (2A/')" with sulfuric acid solu- 
tions Hg, HgO, KOH (IN) with alkaline solutions^^ and the 
normal calomel electrode with the salt solutions, each being 
checked against the standard hydrogen electrode occasionally. 

The electrodes were always, when possible, made of square 
sheets, exactly one centimeter on each side. A projection left 
on this sheet or a stout wire soldered to the back, passed up 
through a glass tube. The back and connecting strip up to the 
glass were heavily coated with asphalt. This was found to be 
very satisfactory, the asphalt being unattacked in all the solutions 
used and having no tendency to peel off as paraffine does. In 
every case the actual resistance of the electrode and lead itself was 
determined and corrections made for the ohmic resistance drop 
if it were appreciable. 

The surface wherever possible, was polished with No. 0000 
emery paper. Any further polishing seemed useless as the sur- 
face is so soon roughened after passing the electrolyzing current. 
All measurements were made with the apparatus in a thermostat 
at 25°C., regulated to within 0.2°C. 

MATERIALS. 

All hydrogen overvoltages were measured in pure two-normal 
sulfuric acid, care being always taken to saturate the solution first 

"98 g. HjSO, per 1,000 g. of water. 

" In calculating tlie oxygen overvoltages the electromotive force of the hydrogen- 
oxygen cell was taken as 1.227 volts. See L,ewis and Randall J. Am. Chem. See. 
36, 1969 (1914). 



EFFEICT OF CURRENT DENSITY ON OVERVOLTAGE. 63 

with hydrogen. Oxygen overvoltages were determined in one 
normal potassium hydroxide. No particular effort was made to 
saturate this solution with oxygen as the results were too 
unsteady to warrant it and were not improved by preliminary 
saturation. For the halogen overvoltages, saturated solutions of 
the sodium or potassium halide were used, saturated further with 
the pure halogen. The strong solutions were used to give a good 
conducting solution and to avoid depletion of ions at the electrode. 
The saturation with the halogen is obviously necessary since the 
equilibrium potential with no current will only be obtained 
under that condition. 

Wherever possible the pure metals were obtained for electrodes. 
No extraordinary care was exercised however as the measure- 
ments could not be made with a precision to necessitate it. 

The procedure in making a run was to set the current at the 
desired value and make the electrode potential determination within 
one minute, then raise the current and make the next measure- 
ment, etc. The objection will immediately be raised against this 
procedure that insufficient time is allowed for the electrode to 
come to a constant value, but it was found without question that 
more nearly reproducible values could be obtained on the increase 
and decrease of current in this way. If five or ten minutes were 
allowed at each step the electrode had so changed by the time a 
complete run had been made, from the lowest current to the 
highest and back, that the last value was several tenths of a volt 
dift'erent in some cases from what it had been for the same current 
at the start. Particularly with the higher currents the measure- 
ments were made quickly to avoid destroying the surface and to 
prevent excessive heating. In general measurements were made 
both on the increase and decrease of current, but only the values 
for increasing current are listed. Check runs on newly made 
electrodes were made in every case ; these were considered satis- 
factory if the forms of the curves were similar and the deviation 
of the two not more than 0.1 volt. One of the runs only is 
listed and not an average of the two as the form of the curve 
is believed to be more important than absolute values. 



64 



M. KNOBEL, P. CAPLAN, AND M. EISEMAN. 



RESULTS. 

The results are listed in Tables I to V and shown graphically 
in Fig. 5 to 9. The current density is given in milliamperes per 

Table I. 
Hydrogen Overvoltages at 25° C. 



Current 






Overvoltage in Volts. 






density 
















milL 
















amp. 

per 

sq. cm. 


Au 


Cd 


Cu 


Plat- 
inized 
Pt 


Smooth 
Pt 


A! 


Graph- 
ite 







0.466 




0.000 






0.0022 


0.1 


o.m 


0.651 


0.35 i 


0.0034 




0.499 


0.3166 


1 


0.241 


0.981 


0.479 


0.0154 


0.024 


0.565 


0.5995 


2 


• • • • 






0.0208 


0.034 


0.625 


0.6520 


5 


0.332 


1.086 


0.548 


0.0272 


0.051 


0.745 


0.7250 


10 


0.390 


1.134 


0.584 


0.0300 


0.068 


0.826 


0.7788 


50 


0.507 


1.211 


• ■ ■ • 


0.0376 


0.186 


0.968 


0.9032 


100 


0.588 


1.216 


0.801 


0.0405 


0,288 


0.996 


0.9774 


200 


0.668 


1.228 


0.988 


0.0420 


0.355 


1.176 


1.0794 


500 


0.770 


1.246 


1.186 


0.0448 


0.573 


1.237 


1.1710 


1000 


0.798 


1.254 


1.254 


0.0483 


0.676 


1.286 


1.2200 


1500 


0.807 


1.257 


1.269 


0.0495 


0.768 


1.292 


1.2208 


Current 






Overvo 


tage in Vc 


)ltS. 






density 
















mill. 


1 














amp. 

per 

sq. cm. 


Ag 


Sn 


Fe 
electrode 


Chem- 
metal 


Brass 


Monel 
metal 


Dur- 
iron 







0.2411 


0.2026 


0.2824 






0.1680 


0.1 


0.2981 


0.3995 


0.2183 


0.3160 


0.3832 


0.1911 


0.1710 


1 


0.4751 


0.8561 


0.4036 


0.6592 


0.4967 


0.2754 


0.1970 


2 


0.5787 


0.9469 


0.4474 


0.7249 


0.5346 


0.3022 


0.2136 


5 


0.6922 


1.0258 


0.5024 


0.7885 


0.5960 


0.3387 


0.2443 


10 


07618 


1.0767 


0.5571 


0.8349 


0.6459 


0.3832 


0.2856 


50 


0.8300 


1.1851 


0.7000 


0.9322 


0.8011 


0.5345 


0.5096 


100 


0.8749 


1.2230 


0.8184 


0.9696 


0.9104 


0.6244 


0.6129 


200 


0.9379 


1.2342 


0.9854 


0.9989 


1.1088 


0.7108 


0.7240 


500 


1.0300 


1.2380 


1.2561 


1.0407 


1.2318 


0.8619 


0.8591 


1000 


1.0890 


1.2306 


1.2915 


1.0682 


1.2544 


1.0716 


1.0205 


1500 


1.0841 


1.2286 


1.2908 


1.0859 


1.2491 


1.2095 


1.1400 



square centimeter and the overvoltage in volts. The overvoltage 
is given to tenths of a millivolt where the steadiness of the indi- 
vidual values seemed to warrant it, although it is unlikely that 
the measurements could be reproduced to better than two to three 



EFFECT OF CURRENT DENSITY ON OVERVOLTAGE. 



65 




si|o.\ a\ jaB)|0:ija.\o 



66 



M. KNOBEL, P. CAPLAN, AND M. EISEMAN. 



millivolts. At the higher current densities the potential often 
became rather variable and was recorded therefore in some cases 
only to hundredths of a volt. 

The values for hydrogen overvoltage on zinc, bismuth and 



TabIvE I. — Continued 
Hydrogen Overvoltages at 25° C. 



Current 




Overvoltage in Volts 






density 










m 












mill. 












amp. 


Zn 


Carbon 


Bi 


Ni 


Pb 


per . 












sq. cm. 












1 


0.716 




0.78 


0.563 


0.52 


2 


0.726 







0.633 




5 


0.726 


0.64 


0.98 


0.705 


1.060 


10 


0.746 


0.70 


1.05 


0.747 


1.090 


50 


0.926 


0.82 


1.15 


0.890 


1.168 


100 


1.064 


0.89 


1.14 


1.048 


1.179 


300 


1.168 


1.04 


1.20 


1.130 


1.217 


500 


1.201 


1.10 


1.21 


1.208 


1.235 


1000 


1.229 


1.17 


1.23 


1.241 


1.262 


1500 


1.243 


1.23 


1.29 


1.254 


1.290 



Current 


Overvoltage 


Current 


Overvoltage 


Current 


Overvoltage 


density 


Hg 


density 


Te 


density 


Pd 


0.00 


0.2805 


0.000 




0.000 




0.0769 


0.5562 


0.416 


0.6564 


0.227 


0.0546 


0.769 


0.8488 


0.832 


0.3505 


1.135 


0.1392 


1.54 


0.9295 


1.667 


0.4162 


2.27 


0.1820 


3.87 


1.0060 


4.16 


0.4405 


4.54 


0.2349 


7.69 


1.0361 


8.32 


0.1530 


11.35 


0.3165 


38.7 


1.0634 


41.6 


0.4705 


22.7 


0.4034 


76.9 


1.0665 


83.2 


0.4733 


113.5 


0.7205 


154 


1.0751 


166.7 


0.4986 


227 


0.8607 


387 


1.1053 


416 


0.5370 


454 


0.9521 


769 


1.108 


832 


0.5940 


1135 


1.0513 


1153 


1.126 


1250 


0.6590 


2270 
3400 


1.1168 
1.1570 



nickel are not plotted, but the form of the curves for zinc and 
nickel is not dissimilar to that of graphite, and the form of the 
bismuth curve resembles that of lead. 

The following notes supplement the table of hydrogen over- 
voltages : 



EFFECT OF CURRENT DENSITY ON OVERVOLTAGE. 



67 




s;[ov ni 9aB;iOAJ3AO 



68 



M. KNOBEL, P. CAPLAN, AND M. EISEMAN. 



The graphite was a very soft variety, the exposed surface of 
which was rubbed with No. emery paper. 

The tellurium was badly attacked by the acid so that the 
results are probably of no value. 



Table IL 
Chlorine Overvoltages at 25° C. 



Platinized Pt 


Smooth Pt Grapiiite 


Current 
density 
mili. amp. 
per sq. cm. 


Overvoltage 


Current 
density 
mili. amp. 
per sq. cm. 


Current ! 
Overvoltage ?^ensity | Over- 
^ mill. amp. voltage 
per sq. cm. 


1.1 

5.7 
14.5 
21.7 
38.8 
60 
100 
200 
520 
1340 
1490 


0.0060 

0.0140 

0.0180 

0.0190 

0.0210 

0.024 

0.026 

0.035 

0.050 

0.089 

0.103 


1.1 

5.7 
11.4 
22.8 
43.0 
100 
200 
500 
750 
1000 
1350 


0.008 

0.0199 

0.0299 

0.0378 

0.0457 

0.0540 

0.0870 

0.161 

0.212 

0.236 

0.263 


40 
70 
100 
200 
500 
740 
980 
1131 


0.186 
0.193 
0.251 
0.298 
0.417 
0.466 
0.489 
0.535 



Table III. 
Bromine Overvoltages at 25° C. 



Platinized 


Platinum 


Smooth 


Platinum 


Graphite 


Current 




Current 




Current 




density 
mili. amp. 


Overvoltage 


density 
mili. amp. 


Overvoltage 


density 
mili. amp. 


Overvol- 
tage 


per sq. cm. 




per sq. cm. 




per sq. cm. 




10 


0.002 


20 


0.002 


10 


0.002 


30 


0.005 


30 


0.004 


30 


0.008 


50 


0.007 


50 


0.006 


50 


0.016 


100 


0.012 


230 


0.033 


100 


0.27 


200 


0.025 


300 


0.357 


200 


0.54 


300 


0.041 


360 


0.113 


300 


0.81 


420 


0.056 


400 


0.156 


390 


0.108 


500 


0.069 


420 


0.164 


550 


0.163 


590 


0.082 


440 


0.178 


740 


0.218 


760 


0.130 


520 


0.266 


840 


0.253 


940 


0.202 


720 


0.379 


990 
1110 
1210 


0.329 
0.356 
0.400 



EFFECT OF CURRENT DENSITY ON OVERVOETAGE. 



69 





































































































































































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sjio^ ni 38b)ioaj9ao 



70 



M. KNOBEL, P. CAPLAN, AND M. EISEMAN. 



The zinc was obtained from a dry cell casing. It was suffi- 
ciently pure so that it would not dissolve in the acid. 

The bismuth sample was a piece of the crystalline metal, coated 
with asphalt except for approximately one square centimeter of 
its surface. No attempt was made to smooth the surface. 

Table IV. 
Iodine Overvoltages at 25° C. 



Platinized Platinum 


Smooth 


Platinum 


Graphite 


Current 




Current 




Current 




density 
mili. amp. 


Overvoltage 


density 
mili. amp. 


Overvoltage 


density 
mili. amp. 


Over- 
voltage 


per sq. cm. 




per sq. cm. 




per sq. cm. 




10 


0.006 


12.3 


0.0039 


1.2 


0.002 


20 


0.012 


23 


0.0070 


5.7 


0.007 


40 


0.022 


50 


0.0127 


11.7 


0.0139 


110 


0.032 


90 


0.0216 


19.7 


0.0239 


220 


0.050 


130 


0.0353 


34.8 


0.0348 


400 


0.070 


200 


0.0510 


50 


0.0538 


710 


0.118 


310 


0.0744 


100 


0.0974 


810 


0.130 


520 


0.120 


200 


0.175 


1000 


0.196 


690 


0.150 


400 


0.315 


1300 


0.216 


1030 


0.220 


590 


0.451 


1460 


0.266 


1160 
1330 
1500 


0.245 
0.277 
0.292 


840 


0.645 



Table V. 
Oxygen Overvoltages at 25° C. 



Current 

density 

mili. 








Overvoltage in 


Volts 
























amp. 
per 


Soft 
Graph- 


Au 


Cu 


Ag 


Chem- 
metal 


Smooth 
Pt 


Plat'z'd 
Pt 


Smooth 

Ni 


Spongy 
Ni 


sq. cm. 


ite 


0.673 


0.422 








0.398 






1 


0.525 


0.580 


0.55 


0.721 


0.353 


0.414 


5 


0.705 


0.927 


0.546 


0.674 


0.90 


0.80 


0.480 


0.461 


0.511 


10 


0.896 


0.963 


0.580 


0.729 


1.02 


0.85 


0.521 


0.519 


0.563 


20 


0.963 


0.996 


0.605 


0.813 




0.92 


0.561 




.... 


50 




1.064 


0.637 


0.912 


1.10 


1.16 


0.605 


0.676 


0.653 


100 


1.091 


1.244 


0.660 


0.984 


1.084 


1.28 


0.638 


0.726 


0.687 


200 


1.142 




0.687 


1.038 


1.101 


1.34 


• • • • 


.0.775 


0.714 


500 


1.186 


1.527 


0.735 


1.080 


1.127 


1.43 


0.705 


0.821 


0.740 


1000 


1.240 


1.63 


0.793 


1.131 


1.154 


1.49 


0.766 


0.853 


0.762 


1500 


1.282 


1.68 


0.836 


1.14 


1.175 


1.38 


0.786 


0.871 


0.759 



EFFECT OF CURRENT DENSITY ON OVERVOLTAGE. 



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S^IOA 'n aSB^iOAaaAO 



72 M. KNOBEL, P. CAPLAN, AND M. EISEMAN. 

The nickel was electrolytically deposited on a platinum sheet 
from a pure nickel sulfate solution. 

The brass sample was a piece which contained 60 per cent 
copper and 40 per cent zinc. 

The palladium became coated with a dense black layer which 
could be wiped off, or which cleared up entirely on standing a 
few minutes, restoring the original bright surface. 

The tin sample also became covered with a black layer, similarly 
to palladium, but this layer was adherent and did not disappear 
on standing. 

The gold, cadmium, copper, aluminum, silver, mercury, pal- 
ladium, platinum and tin electrodes were of metal which was 
"chemically pure." 

The following note applies to the oxygen overvoltages : 

The gold was strongly attacked by the oxygen. After the run 
it was a bright copper red color. On account of the extraordi- 
narily high overvoltage on gold, these values were checked at 
three separate times and the figures given appear to be correct. It 
is possible that the oxide coating (which appears to be very 
adherent) introduces an ohmic resistance, and that there is a 
partial valve action as on aluminum. 

We will leave the theoretical discussion of these results for 
a later article, in which a theory of overvoltage will be outlined. 
The following general observations may be made on the hydrogen 
overvoltages : 

1. The general form of the current density overvoltage curve 
is similar to that of a logarithm curve. Except in a few cases, 
however, a simple logarithm equation cannot be fitted to the 
entire curve. Such an equation which is valid for very low and 
very high currents would show a much sharper bend in the current 
density range from 10 to 200 milliamperes per square centimeter, 
than the observed curves. 

2. Metals generally specified as having a high overvoltage, 
as lead, mercury and cadmium, rise sharply to a high overvoltage 
at low current densities and then increase but little with 
increasing current. 

3. Metals of "low" overvoltage, as copper and gold, show a 
more gradual increase of overvoltage with current, but in 



EFFECT OF CURRENT DENSITY ON OVERVOETAGE. 



73 

















































































































































































































































































































































































































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cc CJ 



SflOA "! 3Sb:)[oaj3ao 



74 M. KNOBEL, P. CAPLAN, AND M. EISEMAN. 

general with the exception of platinum and gold, finally attain as 
high an overvoltage as "high overvoltage" metals. 

4. No hydrogen overvoltages measured by us exceed the value 
of about 1.30 volts^-, but the trend of most of the curves is 
toward this value. 

5. Platinized platinum holds a unique position among these 
other smooth metals in that it maintains its low overvoltage even 
at exceedingly high current densities. In another experiment, not 
listed, the current through a well platinized electrode was increased 
until a spark passed from electrode to solution (at a current 
density of 14 amperes per square centimeter) and the overvoltage 
just before this point was reached was only 0.50 volt. 

No generalizations of importance are apparent in regard to the 
halogen overvoltages, except that platinized platinum shows the 
lowest and graphite the highest values. The forms of the curves 
are widely different, some being nearly linear. 

The oxygen overvoltages are rather less reliable than either the 
hydrogen or halogen overvoltages, due to unaccountable varia- 
tions with time. Even after long polarization at a given current, 
the overvoltage may vary by a tenth of a volt or more. The 
shape of the curves is in general logarithmic. 

SUMMARY. 

Values of the hydrogen overvoltage at twenty-two cathodes ; 
of the chlorine, bromine and iodine overvoltages at three anodes ; 
and of the oxygen overvoltage at nine anodes, have been deter- 
mined and tabulated at various current densities from one milli- 
ampere to one and one-half amperes per square centimeter. All 
measurements were made at 25 °C. ± 0.2° C. 

An investigation of the method of measuring overvoltage has 
led to the conclusion that the use of a small glass tip less than 
one millimeter in diameter, pressed against the active electrode 
surface while the current is passing, will give correct results. 

" While higher values may be found in the literature, we believe they are due to 
imperfect elimination of ohmic resistances. 



EFFECT OF CURRENT DENSITY ON OVERVOLTAGE. 75 

DISCUSSION. 

W. G. HoRSCH^ : In connection with this overvoltage work, 
has Dr. Knobel ever attempted to analyze the commutator method 
by applying equations similar to those that have been developed 
for expressing the rise and decay of current in the ordinary 
copper wire circuits? 

M. Knobee: I have done just that with the curves of over- 
voltage as a function of the time. The course of these curves 
is a function of the concentrations of the gas ; and deducting the 
theoretical equation and making the equation fit that curve, con- 
stants are obtained which involve the concentration of hydrogen 
on the electrode. I hope soon to publish the results. 

P. Caplain : I think it important to emphasize something that 
Dr. Knobel has pointed out. Ultimately, it appears, there is no 
such thing as a high or low overvoltage electrode. If you in- 
crease the current sufficiently, and permit a sufficient lapse of 
time, the hydrogen overvoltages of the metals investigated ap- 
parently tend to rise to the same maximum value, provided no 
secondary reactions take place. The literature of the past has 
considered low and high overvoltage metals, but the results, in 
the last analysis, seem to indicate that this is a fallacy. 

M, Knobel : I have tried all possible methods and have spent 
considerable time trying to get reproducible overvoltage measure- 
ments, but it seems almost impossible. There are unaccountable 
variations with time which apparently can not be eliminated. 

E. O. Benjamin-: I would like to ask ]\Ir. Caplain whether 
the condition that he approaches, in saying that the overvoltage of 
all these metals would be nearly alike, is not an approach to a 
true gas electrode, in eliminating the characteristics of the metallic 
elements ? 

P. Caplain : That is what the results seem to indicate. I 
should not go much further, because Dr. Knobel is personally 
working on the problem. Assuming that the electrode does be- 
come saturated with gas, and applying the gas laws, a value of 
overvoltage may be calculated which corresponds to that obtained 
experimentally. 

E. O. Benjamin: In carrying on the work of electrolysis 

1 Chile Exploration Labs., New York City. 

- Consulting Engr. and Chemist, Newark, N. J. 



76 



DISCUSSION. 



of water on a large scale, in dealing with a square meter 
electrode, taking a characteristic volt-ampere curve, we obtain 
at zero current flow about 1.5 volts as the potential between 
a nickel anode and an iron cathode in a sodium hydroxide solution. 
The volt-ampere curve generally assumes a form similar to the 

3000- 



2500- 



2000- 



1500- 



1000- 



600- 




curve shown in Fig. 1 . We reach point "e" where the curve nearly 
assumes the form of a straight line, and it seems that from the 
point "e" to the point "f," we have full saturation of the elec- 
trodes. Below "e" we have a partial saturation of the electrodes, 
and are gradually building up the gas film. Above "f" the resist- 
ance seems to increase, due to the formation of molecular gas on 
the electrodes and the accumulation of gas bubbles in the elec- 



EFFECT OF CURRENT DENSITY ON OVERVOLTAGE. 77 

trolyte, thereby reducing the effective cross-section of the electro- 
lyte. 

This may have some bearing on the fact that a gas electrode 
is actvialiy formed at a point above "e," which we may assume to 
be the saturation point of the electrode. In many cases this curve 
has been referred to as the decomposition characteristic of a cell ; 
and with the same conditions as to electrolyte, temperature, etc., 
but regardless of pressure, we never vary more than about 0.02 
volt. 

In a large electrode we do not necessarily have a complete film 
of the gas, and below that point when a portion of the metallic 
electrode is exposed, it is what I refer to as an unsaturated con- 
dition, meaning that there is metallic surface which can be coated 
or that will hold a gas film. 

M. Knobel : That is quite in accord with some results which 
I am getting. I think it will appear that the maximum overvolt- 
age occurs when there is a single molecular layer of gas on the 
electrodes ; when you start to build up a second layer you are 
then forming practically free monatomic hydrogen at the maxi- 
mum overvoltage. 

Carl Hering'' : When the electrode is covered with a molar 
film of gas, the voltage rises fifty to a hundred fold, and produces 
an arc over the whole surface, as I showed in a paper some years 
ago. If the electrode is covered completely with a film of gas, 
this arc heats the electrode so quickly that one can melt steel 
under water. 

A. H. W. Aten* (Communicated) : From experiments on the 
scattering of lead cathodes I concluded in 1916'^ that the over- 
voltage for hydrogen evolution might be ascribed to a slow com- 
bination of hydrogen atoms to hydrogen molecules. If the result 
of the present authors, that the overvoltage at high current den- 
sities approaches a limiting value of 1.3 volt, independent of the 
nature of the metal (except in the case of plantinized platinum) 
is considered from this point of view, this would mean that 1.3 
volt possibly corresponds to the potential of atomic hydrogen of 
one atmosphere. Now the potential of atomic hydrogen is given 
by the formula: 

2 Consulting Electrical Engr., Philadelphia, Pa. 

* Prof, of Chemistry, University of Amsterdam, Holland. 

= Proc. Roy. Acad. Sci.. Amsterdam, 18, 1379 (1916). 



78 DISCUSSION. 

Vh = Eh - 0.058 logio Ch- — 0.058 login Ph (1) 
and the potential of molecular hydrogen by 

Vh, = Eh, + 0.058 logio Ch^ — 0.029 logic Ph, (2) 

where Eh, — Eh is, according to the assumption made above, 
equal to 1,3 volt. 

If one mol of hydrogen, at a pressure of one atmosphere, is 
dissolved into atoms at constant volume, the pressure will be two 
atmospheres. The decrease in free energ}% in transforming this 
atomic hydrogen galvanically into molecular hydrogen, will, 
according to (1) and (2) be given by 

2F (Eh, — Eh)+ 2F X 0.058 logio 2. (3) 

Ph, being = 1 and Ph = 2. 

The value of the second term lies within the experimental un- 
certainty, and we can put the decrease of the free energy- equal to 
2 X 96,500 X 1.3 joules = 250,000 joules = 60,000 cal. 

The value of 60,000 cal. for the molal dissociation energy of 
hydrogen is rather low. This figure is calculated from the Bohr- 
Debyes model of the hydrogen molecule, but the experimental 
values are higher. 

Langmuir'^ finds 84.000 cal., and Isuardi' 95.000 cal.. whereas 
Franck, Knipping and Kruger* calculate 81,300 ± 5,700 cal. from 
ionization potentials. Assuming these latter values to be correct, 
it should be concluded that even at the highest current densities 
the concentration of H atoms at the cathode remains less than 
that corresponding to one atmosphere. 

M. Knobel (Coiinuiiiiicatcd) : The discussion by Prof. Aten 
brings up a point of which we were aware, but had excluded from 
the present article, planning to discuss it with other theoretical 
interpretations of the data in connection with a theory of over- 
voltage. In view of the uncertainty in the experimental and cal- 
culated values of the free energy of formation of Ho from Hj, 
we believe one can conclude that the monatomic hydrogen is at 
a pressure of approximately one atmosphere, when the maximum 
overvoltage is reached. 

"Z. f. Elektrochemie, 23, 217 (1917). 
•Z. f. Elektrochemie, 21, 405 (1915). 
"Ber. Deut. physik. Ges. 21, 728 (1919). 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 3, 1923, Dr. Wm. G. Horsch 
in the Chair. 



ELECTROTITRATION WITH THE AID OF THE AIR ELECTRODE.' 

By N. Howell Furman.* 

Abstract. 
A brief report of further progress in the study of some uses 
of the air electrode is given. The results indicate clearly that 
the air electrode is capable of giving satisfactory results in 
electrotitration, either in the presence or absence of oxidizing 
agents. 

INTRODUCTION. 

The results of a preliminary study of some applications of 
cells composed of a AT calomel electrode in conjunction with some 
one of the electrodes: 

(A) Oxygen Electrode, 

(B) Air Electrode, 

(C) Platinized Platinum Electrode, 

(D) Burnished Platinum Electrode, 

have been presented in a recent communication.^ 

It was shown in a general way that the oxygen electrode-iV 
calomel electrode cell may be used to construct titration curves 
which are in large measure analogous to those which are obtained 
in the familiar hydrogen electrode titrations. Special emphasis 
was placed upon the use of the oxygen electrode in the acidimetry 
and alkalimetry of solutions which contained strong oxidizing 

agents. , 

The majority of the results which were there presented were 
obtained with the aid of the oxygen electrode. A number of 

1 Manuscript received January 31, 1923. 

» Cor^tribution from the Chemical Laboratory of Prmceton Unn-ers.ty. 
3 Furman. J. Am. Chem. Soc. 44. 2,685 (1922). 

79 



8o N. HOWELL FURMAN. 

results which were obtained by means of the other electrodes 
(B, C and D) were included. After a brief preliminary study, 
the burnished platinum electrode was found to be extremely 
sensitive to minute variations in the details of handling. Recently 
van der Meulen and Wilcoxon* have described the conditions 
under which the burnished platinum electrode may be employed 
successfully. 

The air electrode is very slightly influenced by minor changes 
in the mode of manipulation, in which respect it is superior to 
the platinized and burnished platinum electrodes. The potential 
of an air electrode toward any given solution is subject to the 
well-known drift in value which is ordinarily ascribed to the 
process of oxide formation.^ Nevertheless satisfactory titration 
curves may be obtained either in the presence or absence of 
oxidizing agents. Furthermore, a fair approximation of the 
hydrogen ion concentration may be obtained by making an em- 
pirical calibration of the electromotive force of the air electrode-AT 
calomel electrode cell with the aid of a series of solutions of 
known hydrogen ion concentration. 

Arthur and Keeler^ have described a continuous recording 
apparatus for the measure and control of the alkalinity of boiler 
feed water by means of the air electrode-0.1 A'' calomel electrode 
combination. The electromotive force readings of this cell were 
calibrated in terms of grains of alkalinity per gallon of water. 
They state that this method involving the air electrode was more 
reliable under continuous operating conditions that the colon- 
metric method in the hands of unskilled operators. 

EXPERIMENTAL. 

The apparatus, mode of procedure, details of standardizing 
reagents, and general technique were described in the previous 
paper. It is perhaps well to repeat that the electromotive force 
values were repeatedly referred to the value of a Weston satu- 
rated type standard cell by means of a potentiometer set of 
moderate precision.^ 

* \'an der Meulen and Wilcoxon, Ind. and Eng. Chem., 15, 62 (1923). 

° A brief review of the literature relating to the oxygen and air electrodes was given 
in the previous paper (ref. 3) p. 2686. Data were given relating to the magnitude 
of the drift to be expected. 

« Arthur and Keeler, Power, 55, 768 (1922). 

' Leeds and Northrup students' type potentiometer, and a galvanometer of current 
sensitivity 2 mm. per micro-ampere. 



ELECTROTITRATION BY THE AIR ELECTRODE. 8l 

A number of curves typical of those obtained are plotted in 
Fig. 1. It should be noted that the form of the apparatus made 
it necessary to dilute the solutions somewhat before the titrations 
were commenced. The volume was ordinarily 75 cc. at the 
start of each titration. 






.6 



.5 



.3 



f 



.1 











f 












4' 


/^ a 










/ 


7 


/T^ 






^i 


^ 


w 




^ 






/ 


a 


i 
t 

I 


> (1 

-<- 

t 




^ 


^ 






Jj 




> < 


> ' 


r= ' 




y 





5 /O /5 

CC. AC/D - 



20 



2.5 



30 



Fig. 1. Air Electrode Titrations. 



(1) Titration of 15.87 cc. of 0.09123 N alkali and 8.33 cc. 0.1000 N 
NazCrOi with 0.09986 A' HCl. 

Cal. 14.50, found 14.55 cc. acid to neutralize free alkali. 
Calc. 8.34, found 8.43 cc. acid to transform chromate into dichromate 
(distance o to b curve 1). 

(2) 25 cc. of 0.5000 A^ NaaCOs titrated with 0.5176 A^ H2SO4. 
Point c (bicarbonate point) calc. 12.07, found 12.19 cc. of acid. 

Second inflection (complete neutralization) calc. 24.15, found 24.20 cc. 
of acid. 

(3) Titration of 25 cc. 0.09123 N NaOH with 0.09986 N HCl. Calc. 22.84, 
found 22.93 cc. 

(4) Titration of 25 cc. 0.4937 N NaOH with 0.5050 A^ acetic acid. Calc. 
24.44, found 24.40 cc. 



82 



N. HOWELL FURMAN. 



A qualitative measure of the difference in hydrogen ion con- 
centration of 0.1 A^ hydrochloric acid, as contrasted with 0.5 N 
acetic acid, is given by the relative positions on the voltage scale 
of the end portions of curves (3) and (4) respectively. Point 
c curve (2) represents the completion of the conversion of 
sodium carbonate into bicarbonate. Point a curve ( 1 ) represents 
the neutralization of free alkali in the presence of chromate; 
while point b represents the completion of the conversion of 
chromate into dichromate. 

Fig. 2 contains titration curves for nitric (1) and perchloric 




5 10 15 20 

C C. OF nZAGENT-^ 

Fig. 2. Air Electrode Titrations. 

(1) 25 ec. 0.5285 .V nitric acid titrated with 0.4541 A^ NaOH. Calc. 29.10, 
found 29.15 cc. 

(2) 24. cc. of 0.09986 N HCl titrated with 0.09123 .V NaOH. Calc. 26.27, 
found 26.25 cc. 

(3) Titration of 25 cc. of 0.09497 N HClGi with 0.09123 N NaOH. Calc. 
26.02, found 25.98 cc. 

Data showing the results of No. (4) and (5) will be found in exp. 7, 
Table I. 



ELECTROTITRATIOX BY THE AIR ELECTRODE. 83 

(3) acids, together with a curve for hydrochloric acid (2) for 
purposes of comparison. A salt bridge of approximately 0.1 N 
sodium nitrate was interposed between the solution and the calo- 
mel electrode during the titration of the nitric acid. Curve (4) 
represents the- titration of dichromate, in a mixture of chromate 
and dichromate, with alkali. At the end of this titration all of 
the chromate was converted into dichromate by means of standard 
acid. The distance a to & (curve 5) represents the amount of 
acid required. 

In the previous paper* it was shown that an accurate deter- 
mination of free alkali in the presence of chromate (providing 
the carbonates were absent), or of free acid in the presence of 
dichromate, could be made with the aid of the oxygen or air 
electrodes. The method may be extended to the analysis of 
mixtures of chromate and dichromate as the following results 
will serve to show. 

Solutions of chromate and dichromate were prepared. Each 
solution was standardized against freshly standardized ferrous 
sulfate by the electrometric method of Forbes and Bartlett.^ 
Known portions of the solutions were mixed. The mixture was 
then analyzed by one of the following methods. 

(A) The amount of acid necessary to convert the chromate, 
which was present in the mixture, into dichromate, was deter- 
mined electrometrically. The total amount of dichromate was 
then determined electrometrically either (1) by means of standard 
alkali, or (2) by means of freshly standardized ferrous sulfate, 
after the addition of a large excess of acid. Total alkali re- 
quirement minus acid equivalent to chromate equals alkali 
equivalent to dichromate present. 

(B) The amount of alkali necessary to convert dichromate into 
chromate was determined. The total acid requirement was then 
found (1) by direct titration with standard acid (distance a to & 
curve 5, Fig. 2) or (2) by reduction with standard ferrous sul- 
fate after strongly acidifying the solution. Then, total acid 
requirement minus alkali equivalent to dichromate equals acid 
equivalent to chromate. 

spurman, J. Am. Chem. Soc, 44, 2,685 (1922). 

9 Forbes and Eartlett, J. Am. Chem. Soc. 35, 1,327 (1913). 



84 



N. HOWELIv FURMAN. 



AH of the electrometric methods, as well as a number of other 
physico-chemical methods, agree in finding two sharply defined 
changes in the neutralization curves of chromic acid or of 
acidified chromate solutions. Similar changes appear in the 
curves for the acidification of alkaline chromate solutions. Mar- 
gaillan^" investigated the neutralization of M/30 solutions of 
chromic acid, both by means of conductance titration and hydro- 
gen electrode titration. By both methods a sharp change was re- 
vealed when one mole of sodium hydroxide per mole of chromic 
anhydride (CrOs) had been added; a second sharp change ap- 
peared when two moles of alkali per mole of chromic anhydride 

Table I. 

Electrometric Analysis of Mixtures of Chromate and Dichromate. 
Results No. 1 to 3 are calculated to 0.1 N ; No. 4 to 8 to 0.5 N. 





1 


2 


3 


4 


5 


No. 


Bichromate 


Dichromate 


Chromate 


Chromate 


Method 


Taken 


Found 


Taken 


Found 


Used 




cc. 


cc. 


cc. 


cc. 


(see above) 


1 


8.33 


8.44 


18.05 


17.93 


B 2 


2 


16.67 


16.72 


18.05 


17.96 


B 2 


3 


8.33 


8.44 


7.19 


7.24 


B 1 


4 


16.85 


16.89 


7.19 


7.20 


A 1 


5 


16.85 


16.79 


14 38 


14.45 


A 1 


6 


33.70 


33.78 


14.38 


14.44 


A 1 


7 


16.85 


16.80 


1438 


14.39 


B 1 


8 


33.70 


33.71 


7.19 


7.24 


B 1 



had been added. Hughes" who has recently investigated the 
glass cell (glaskette), with an improved apparatus similar to 
that of Haber and Klemensiewicz^^, presents an interesting curve 
for the neutralization of chromic acid. The two inflections which 
the author obtained with the aid of the oxygen or air electrodes 
appear at hydrogen ion concentrations (empirically estimated) 
which are in fair agreement with those obtained by Hughes. His 
method seems to be the most reliable which has thus far been 
devised for measuring hydrogen ion concentrations in solutions 
of highly colored oxidizing agents. 

«> Margaillan, Compt. rend., 157, 994 (1913). 

1' Hughes, J. Am. Chem. Soc, 44, 2,860 (1922). 

'2 Haber and Klcmensiewicz, Z. physik. Chem., 67, 385 (1909). 



ELECTROTITRATION BY THE AIR ELECTRODE. 



85 



These physico-chemical resuhs have been used as arguments 
for or against (depending upon the view-point of the individual) 
one or the other of the two stoichiometrically equivalent sets of 
reactions : 



I 



{ 



(a) H^CrO. + NaOH 

(b) NaHCrO^ + NaOH 



= XaHCrO^ 
= Xa,Cr04 - 



- H,0 
H.O 



( (a) H(H.Cr.OT + 
Ub) ^^(Na^Cr.O: -f 



2NaOH = Xa^Cr^O; + 2H2O) 
2XaOH = ZXa.CrOi + H,0) 



In this work the second set (II) has been adopted as being 
more probable and convenient in picturing the relations at the 
two points of inflection. ^^ 

Table II. 

Variation of E. M. F. of Air-N Calomel Cell with Changes in 
Hydrogen Ion Concentration. 





Approx. 


Normality 






Approx. 


Normality 




Time 






E. M. F. 
Volt 


Time 
Min. 






E. M. F. 


Min. 










Volt 




Acidic 


Basic 




25. 


Acidic 


Basic 

0.004 




0. 


0.007 




0.640 




0.077 


2.5 


0.007 




0.643 


27.5 




*0.004 


0.086 


5. 


0.007 




644 


30. 




0.004 


0.088 


6. 




0.006 


0.037 


30.5 


6.667 




0.630 


7.5 




0.006 


0.029 


35. 


0.007 




0.632 


10. 




0.006 


0.038 


36. 




0.003 


0.118 


10.5 


0.667 




0615 


38. 


. ■ . • 


0.003 


0.101 


12.5 


0.007 




0.618 


40. 




0.003 


0.101 


14. 


0.007 




0.617 


41. 


0.007 


. , , , 


0.634 


17. 


0.007 




0.616 


45. 


0.007 


> . • • 


0.633 


20. 


0.007 




0.615 


50. 


0.007 


. . . • 


0.630 


21. 




0.004 


0.076 


185. 


0.007 


.... 


0.625 


22.5 




0.004 


0.073 











* Change caused by one drop of approx. 0.5 A^ acid. 

The experience of Arthur and Keeler, as well as numerous 
observations made in the course of this work, point to a field of 
usefulness of the air electrode in approximate hydrogen ion 
concentration measurement and control. Some idea of the readi- 
ness of response of the air electrode to repeated variations in 

'8 A comprehensive discussion of the nature of chromic acid, and the equilibrium 
relations in chrjmate and dichromate solutions, together with abundant literature 
references are to be found in Abesg's Handbuch der anorg. Chem., IV, 1, 2nd half, 
pp. 306-311, Pub. by S. Hirzel, Leipzig, 1921. 



86 DISCUSSION. 

hydrog^en ion concentration may be obtained from the results in 
Table 11. Known quantities of acid and alkali were alternately 
added to a given volume of solution. 

It should be noted that the readings in alkaline solution are 
more sluggish in coming to a state of gradual drift than are 
those in acid solution. 



DISCUSSION. 



]\I. R. Thompson^ : Prof. Furman's paper supplies information 
on an interesting phase of electrode potential measurements, and 
is an important contribution to this subject. 

In his previous paper mentioned, a more extended discussion 
was given of the irreversibility of the electrode. If the oxygen 
(or air) electrode were really reversible, indicating a definite 
equilibrium for oxygen (or equivalent hydroxyl) ions, the meas- 
urements obtained should be complementary to those of hydrogen 
ion concentrations by the reversible hydrogen electrode and would 
readily serve to calculate the latter concentrations. This depends, 
of course, upon the well-known equilibrium of hydrogen and 
hydroxyl ions in water, giving at about 25° C. the relationship 

^ 10-1^ 



CoH — 



Or in Sorensen units, pH r= 14 — pOH. Physico-chemical 
neutrality exists at pH = pOH ^ 7 (which is the end point 
only when strong acids and bases are combined), and in the 
diagrams this point is represented roughly by an e. m. f. not 
far from 0.3 volt. 

Actually, Prof. Furman and others have shown that the oxygen 
(or air) electrode is not quite reversible and that measurements 
by means of it only serve, at best, to calculate approximate hy- 
droxyl and hydrogen ion concentrations, if the latter are desired. 
This condition does not interfere, however, with extensive appli- 
cations of the electrode for relative determinations, such as the 
accurate establishment of the end points in certain classes of 

1 Assoc. Chemist, Bureau of Standards, Washington, D. C. 



ELECTROTITRATIOX BY THE AIR ELECTRODE. 87 

titrations and the paper has demonstrated this fact satisfactorily. 
We may expect a rapidly increasing field of usefulness for the 
air electrode. 

N. H. FuRMAN : I hope that the accuracy of this method of 
measuring hydrogen and hydroxyl ion concentrations will not be 
taken too seriously. The experience of the research department 
of Leeds & Northrup Co.- and my own seem to point out that 
about all you can hope for is an accuracy of one-half of a Soren- 
sen (pH) unit. 

I did not wish to give the impression that this electrode will 
give values for hydrogen or hydroxyl concentration of the same 
order of accuracy as the hydrogen electrode. It does serve as a 
rough substitute for the hydrogen electrode in some cases, where 
the solution is exposed to air and must remain so. It has some 
usefulness in rough control work. 

O. C. Ralston^ : For over a year we have been using an air 
electrode one centimeter square and heavily platinized at the 
Pacific Experiment Station of the Bureau of Mines (Berkeley, 
Calif.) for the purpose of following the course of hydrolytic 
reactions, either on the large scale or during titration in the la- 
boratory. It is of great use in following hydrolytic purification 
of electrolytes of zinc sulfate, copper sulfate, or in preparing 
iron-free aluminum sulfate solutions. 

We found it necessary to study the air electrode in much the 
same way that Prof. Furman has done and we agree, I think, 
almost entirely with his conclusions. The most important thing 
about it is that the air electrode can not be used as an exact 
measure of hydrogen ion (or hydroxyl ion) concentration, but 
as an indicator of the end of certain reactions, due to changes in 
direction of the voltage-titration curve or voltage-time curve, it 
is very satisfactory. I had hoped to present a paper at this meet- 
ing on the more practical applications of the air electrode, but 
will have to postpone its presentation. 

For such a reaction as the separation of ferric iron from a 
copper sulfate solution, using powdered limestone or copper oxide 
for hydrolyzing the ferric sulfate, the voltage-titration curve is 

= Private communication from Dr. I. B. Smith of Eeeds & Northrup Co. 
3 U. S. Bureau of Mines, Berkeley, Calif. 



88 DISCUSSION. 

almost horizontal till nearly all the iron has been precipitated as 
a basic salt, and then the voltage suddenly drops, indicating the 
end of the reaction. Chemical control of this hydrolysis is diffi- 
cult, because if a sample of the pulp is filtered at this point the 
iron stays in the filtrate as a colloidal compound which makes the 
solution look like coffee. Under these conditions it is difficult 
for the chemist to determine if all the iron in true solution has 
been hydrolyzed. 

The air electrode, of course, functions in oxidizing solutions 
where the hydrogen electrode fails, especially solutions containing 
ferric iron. Since most technical operations with inorganic com- 
pounds in solution are complicated with the presence of iron in 
the solution, the hydrogen electrode has previously found little 
use in this field. On the other hand, the air electrode is not only 
satisfactory but more easily manipulated, because the solutions in 
practice are usually saturated with air or are stirred or agitated 
with air so that the form of air electrode that can be used is ex- 
tremely simple. 

W. G. HoRSCH* : In studying methods of this sort, starting 
out possibly with pure solutions and then trying to apply the 
results to solutions that contain other constituents, we must be 
careful that the method is peculiar to the reaction that we are 
studying or to the endpoint that we wish to obtain. 

* Chile Exploration Labs., New York City. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 3, 1923, Dr. Wm. G. Horsch 
in the Chair. 



THE HYDROGEN ELECTRODE IN ALKALINE SOLUTIONS.' 

By A. H. W. Aten.« 

Abstract. 
When a hydrogen electrode, saturated with hydrogen, is in 
equihbrium with 0.1 A/" HCl, it is in the same state of equihbrium 
with 1.0 A'' HCl, and vice versa. This is not the case, however, 
when the solution of an alkali is used in place of an acid. When 
a hydrogen electrode in equilibrium with 1.0 A^ NaOH is put in 
0.1 A'' NaOH, or the reverse, a considerable time period is required 
to reach a new equilibrium. The same phenomenon is observed 
in a more marked degree when the electrode is changed from 
0.1 N NaOH to 0.1 A'' HCl, or the reverse. The explanation 
suggested is that the electrode must absorb Na or give it off, as 
the case may be, in order to reach an equilibrium with the final 
solution. [C. H. E.] 



In the course of an investigation, in which a hydrogen electrode 
was brought into contact with solutions of varying alkalinity, it 
was found that the potential in a given solution was markedly 
afifected by the alkalinity of the preceding solution. This phenom- 
enon was further examined, and the following is an account 
of part of the results. 

In the apparatus shown in Fig. 1 the tube A, containing the 
hydrogen electrode, is filled with a solution of a given alkalinity, 
say 0.1 A'', and the tube B with a solution of diff"erent alkalinity, 
say 1.0 N. After the hydrogen electrode has reached equilibrium 
in the 0.1 A^ solution, this solution is removed through the tap C, 
and the \.0 N solution, which has been saturated with hydrogen,. 
is introduced through the tap D. The potential of the hydrogen 

1 Manuscript received January 15, 1923. 

' Prof, of Chemistry at the Univ. of Amsterdam. 

89 



90 



A. H. W. ATEN. 



electrode is measured against a decinormal calomel electrode. The 
liquid junction is made by a saturated solution of potassium 
chloride. The values given are those immediately measured, 
without attempting to correct them further for liquid potentials. 
The temperature was room temperature, about 18° C. The 
electrodes consisted of gold sheet, 0.5 x 3 cm., covered with pal- 
ladium black by electrolyzing a solution of palladium chloride (0.3 
per cent palladium) with 0.1 amp. for 5 min. Then these 
electrodes were cathodically polarized in a solution of sulfuric 
acid, in order to reduce the absorbed palladium chloride, and to 
charge them with hydrogen. 




When an electrode thus treated was brought into contact with 
0.1 A'' HCl, contained in tube A, the potential rose in 8 min. 
from +0.340 to +0.400. In contact with 1.0 A^ HCl it rose 
from +0.288 to +0.343 in 14 min. Under these circumstances 
the equilibrium was reached in a short time. It should be 
observed that, in bringing the electrode into the tube A, the 
entering of some air could not be avoided. Hence the potential 
is initially too negative. 



THE HYDROGEN ELECTRODE. 9I 

When now, after equilibrium was reached in 0.1 A'' HCl, this 
solution was replaced by 1.0 TV HCl, which had been saturated 
with hydrogen in the tube B, the potential was immediately 
-f- 0.343. In the same way, when 1.0 N HCl was replaced by 
0.1 A'' HCl, the potential was immediately +0.401. These are 
sensibly the equilibrium potentials. 

From this observation it follows that, when a hydrogen elec- 
trode, saturated with hydrogen, is in equilibrium with 0.1 A'' HCl, 
it is in the same state in equilibrium with 1.0 A?" HCl, and vice 
versa. This is no longer the case when a solution of an alkali is 
used in place of an acid. 

If a hydrogen electrode, which is in equilibrium with 1.0 A^ 
NaOH, is brought into 0.1 AT NaOH, the potential is at the 
beginning some 20 millivolts too positive, and reaches after some 
time the equilibrium potential for 0.1 N NaOH. 

On the other hand, when an electrode, which is in equilibrium 
with 0.1 A'' NaOH, is brought into contact with a solution of 
1.0 A'' NaOH, its potential is at first some 20 millivolts too nega- 
tive and falls more or less slowly to the equilibrium potential. 
The same phenomenon is observed, and in a more marked degree, 
when a hydrogen electrode is brought from 0.1 A^ NaOH into 
0.1 N HCl. 

It is evident that a hydrogen electrode in an acid should behave 
otherwise than in an alkali, since in an acid the only active sub- 
stance on the electrode is hydrogen, while in sodium hydroxide 
sodium, also may be electromotively active. 

If metallic sodium forms a solid solution with palladium, the 
electrode cannot be in equilibrium with a solution of sodium 
hydroxide, unless it contains metallic sodium at a certain concen- 
tration, which is determined by the hydrogen potential, i. e., by 
the hydroxyl ion concentration, and also by the sodium ion concen- 
tration. The electrode is therefore a sodium electrode as well as 
a hydrogen electrode. 

Let us suppose that the potential of the sodium-palladium 
electrode is a logarithmic function of the sodium content, then the 
potential will be given by an equation of the form : 

Ej,, = e^, — 0.058 log.o C^., + 0.058 log.o C^.* (1) 



92 A. H. W. ATEX. 

where C^^ denotes the concentration of the metalHc sodium in 
the palladium, and C^^+ the concentration of sodium ions in the 
solutions. e,sa is a constant. 

The potential of the hydrogen electrode is given by 

Eh = ^oH — 0.058 log.o CoH- (2) 

When we put C^j = 1 for an electrode which, both with 
respect to hydrogen and to sodium, is in equilibrium with a 
solution for which Cx^* = 1 and Cqh" = 1. then it follows, 
while E.N-a must be equal to Eh) 



Hence the sodium concentration of an electrode in equilibrium 
with a solution of sodium hydroxide of the concentration Cqh- 
and Cx-+ must be : 

Cxa ^== Cx-j • CoH" (3) 

If now an electrode, which is in equilibrium with a solution of 
the concentration C^/ • C^,j^- is brought into contact with a 
solution of the concentration C^^-" • Cqh- its hydrogen potential 
will be : 

Eh = e — 058 log.o C;h- (4) 

and its sodium potential 

Esa = e — 0.058 log.o Csa- CoH- + 0.058 log.o C;.,^ (5) 

and the difference: 

E,., - Eh - 0.058 log.o -^^^^^""r (6) 

If thus an electrode, charged with hydrogen at one atmosphere, 
is brought from 0.1 A^ HCl into 0.1 N XaOH, the electrode is not 
in equilibrium with this latter solution, because it contains no 
sodium. It will therefore, in an alkaline solution, lose hydrogen 
and take up sodium, according to the equation : 

H + Na+ - H+ + Na 

If this reaction takes a certain time, the electrode will at first 
be too negative, and approach the equilibrium potential, as the 
above given reaction proceeds. 



THE HYDROGEN ELECTRODE. 



93 



In the same way, if an electrode is brought from 1.0 A'' NaOH 
into 0.1 A'' NaOH, it will be, according to the equations (4) and 
(5) 0.058 volt more positive, if it behaves fully as a sodium 
electrode, and 0.058 volt more negative, if it acts fully as a 
hydrogen electrode. Now neither of these is probable, so one will 
find a value that lies between the potential of the sodium electrode, 
and that of the hydrogen electrode. In any case, however, the 
potential must at first be more positive than the equilibrium 
potential. 



40 



.0 



O 4i 











-■ ■ I 1 
riG. 2 
















^^^ 


5^ 












A 






f 










/ 




' 


0-4. 






J 










/ 










1 








1 


r 










/ 










/ 

































SO 



/20 
Time in Minutes 



/eo 



Fig. 2 shows two curves which give the potential as a function 
of time for two electrodes which had been in contact with a 
solution of sodium hydroxide, and were then brought into 0.1 A/' 
HCl. "A" relates to an electrode covered with platinum black, 
that had been in contact with 1 A'' NaOH for three days, during 
which time a slow current of hydrogen was passed through the 
apparatus. "B" is the curve for an electrode, covered with palla- 
dium black, which was left in 0.1 A'' NaOH for thirty hours. 
Both electrodes were completely immersed in the liquid. It is seen 
that the potential is at first some 40 or 50 millivolts too positive 
and that, after an hour, the equilibrium potential is approached, 
though not yet fully reached. 

The same behavior is found when an electrode is brought from 
a stronger alkaline solution into a weaker one. In Fig. 3 the curve 



94 



A. H. W. ATEN. 



"C" represents the potential for an electrode which has been in 
contact with 0.1 A^ NaOH and is then put into a 0.01 A'^ solution. 
Curve "D" gives the potential, when a 1.0 A^ solution of NaOH 
is replaced by a 0.1 iV solution. In the latter case the potential 
was, after an hour, still 0.008 volt too positive. Next morning 
the equilibrium potential was reached. The total difference 
between the potential immediately found and the equilibrium 



I. OS 



I 



$ 



i.lO 











1 

riG. 3. 


































/ 






V— C 
















f 


/ 


















I 


















































































^ 




41 





.Z)_. 


'-"""" 










/ 





































60 /go 

Time /n Minutes 



/eo 



potential is here less than for the curve "C," because this electrode 
had been in contact with the 1.0 A/" NaOH for two hours only, 
while the electrode C remained thirty hours in the 0.1 A^ solution. 
The reverse is observed when an electrode is brought from 
an acid solution into an alkaline solution, or from a weaker alka- 
line solution into a stronger one. This is shown by the curves in 
Fig. 4, of which "E" relates to an electrode which was brought 
from 0.1 N HCl into 0.1 N NaOH. "F" gives the potential, 
when passing from a 0.01 A^ solution of NaOH to a 1 A^ solution. 



THE HYDROGEN ELECTRODE. 



95 



and "G" when a solution of 0.01 A^ NaOH is replaced by a 0.1 iV 
solution. 

The same phenomena are observed when the electrode has been 
charged with hydrogen and sodium by cathodic polarization. The 
apparatus, shown in Fig. 5, permits polarizing an electrode "A" 
in a solution of NaOH, while a current of hydrogen is passed 
through this solution, and through a second solution, contained 



t.os 






V 
















\ 




nQ.<i 








\ 












•— 


^ 


, v 


■^ 


* 


• Q 




















1. lO 
































5 




\ 












i 




\ 


-_ 


"• * 






r 


1.15 
















o 






io 




/ 


zo 



Timv in Minuter 



in the tube B, which is in this way freed from oxygen. When 
the electrode "A" is polarized for 10 min. with a current of 10 
milliamperes and the current is then broken, the potential, immedi- 
ately after polarization, is found too positive. 

The deviation from the equilibrium potential increases with 
increasing dilution of the alkali as follows: 



Concentration of NaOH 

1.0 A^ 
0.49 A^ 
0.21 A^ 
0.083 N 



Deviation millivolts 



4 

6 

13 



96 



A. H. W. ATEX. 



This may be explained by observing that during the electro- 
lysis the liquid in contact with the electrode is more strongly 
alkaline than the bulk of the liquid, because of the discharge of 
hydrogen ions at the cathode. This concentration polarization 
gives the cathode a too positive potential. In consequence the 
electrode takes up more sodium from the solution than corre- 
sponds to the equilibrium potential. The electrode remains, 
therefore, some time after polarization, too positive. 



^\^': 



'^ 




As the relative increase in alkalinity during electrolysis is 
greatest for the more dilute solutions, the effect on the potential 
will be greatest in solutions with small alkali content. 

When now, a short time after polarization, the solution is 
diluted with its own volume of water, the potential is again 
found too positive. This can be ascribed to the fact that the 
electrode is still too positive as a result of the polarization. 

If, on the other hand, the electrode was polarized in 0.005 A^ 



THE HYDROGEN ELECTRODE. 97 

NaOH, and then, immediately after polarization, a strong solu- 
tion of NaOH was introduced, the potential was found 22 milli- 
volts too negative, when the resulting solution was 0.3 A^. This 
experiment is more decisive, because it shows that the electrode, 
though at first too positive, becomes too negative by greatly 
increasing the alkali content. The most certain proof that a 
hydrogen electrode in alkali acts partly as a sodium electrode 
would be given if it were possible to show that in increasing the 
alkali content the electrode takes temporarily a more negative 
potential. This would mean that by increasing the alkali content 
ten times, the electrode should be more than 58 millivolts too 
negative. So great a value was never found. 

One can however leave the hydroxyl ion concentration almost 
unchanged, and increase the sodium ion concentration by adding 
a strong solution of NaCl to a weak solution of alkali. 

In this case the potential of an electrode must, according to 
equation (5) become more negative if it behaves as a sodium 
electrode, and remain approximately constant if it acts as a 
hydrogen electrode. Now it was found that the potential of an 
electrode, covered with smooth palladium, after polarization in 
0.01 N NaOH fell as much as 30 millivolts, when a strong 
solution of sodium chloride was added, so as to make the liquid 
0.2 A^ with respect to sodium chloride. 

When the electrode is polarized in a solution containing 
NaCl -|- NaOH, the potential after polarization is about 20 
millivolts more positive than in a solution which is only 0.01 A^ 
to NaOH, corresponding to a greater sodium content of the 
electrode. Now it is evident that the electrode should take up 
more sodium in this latter experiment, because polarization in a 
solution of NaOH with a great excess of NaCl gives rise to a 
stronger alkalinity at the cathode than in NaOH alone. In the 
first case the hydroxyl ions are removed by diffusion only, in the 
second case by diffusion and by the current. 

The same experiment was repeated with an electrode covered 
with palladium black, because smooth palladium contains a rela- 
tively small quantity of hydrogen, and the electrode is therefore 
very sensitive to oxygen. So a trace of oxygen, contained in 
the solution of sodium chloride, might give the electrode a too 



^8 A. H. W. ATEN. 

negative potential. Here a saturated solution of NaCl was used, 
which had been boiled, and saturated with hydrogen for two 
hours. Only a small quantity of this liquid was introduced into 
0.01 N NaOH. The potential fell immediately from +1.043 
to -1-1.012 volt and rose afterwards very slowly to the equi- 
librium potential. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 3. 1923, Dr. Wm. C. Horsch 
in the Chair. 



THE REACTIONS OF THE LEAD STORAGE BATTERY' 

By M. Knobel- 

Abstract, 

The theories of the lead storage battery are discussed. The 
results of the author's investigations, together with the work 
of IMacInnes, Adler and Joubert, complete the evidence in 
favor of the Gladstone and Tribe theory of the reactions in the 
lead storage battery. The claim of Fery that only one mol of 
sulfuric acid is used per two faradays on discharge is not sup- 
ported, which tends to disprove the theory he proposes. 



The theory of the reactions of the lead storage battery proposed 
by Fery^ is represented by the following equation for discharge: 

Pb + H,SO, + Pb,0, = PbSO, + H.O + 3PbO, (1) 

or possibly 

Pb + H3SO, + PboOa = PbSO, + H2O + PbO, (2) 

It differs from the generally accepted theory of Gladstone and 
Tribe* represented by the equation 

Pb + PbO, + 2H,SO, 3= 2PbSO, + 2H2O (3) 

in the supposition that there is a higher oxide of lead than the 
peroxide on the anode which changes over to the peroxide on 
discharge. A consequence of this supposition is that only one 

^ Manuscript received November 22, 1922. 

3 Contribution from the Rogers Laboratory of Physics, Electrochemical Labora- 
tory. Massachusetts Institute of Technology. 

»Lumiere Elec, 34, 305 (1916); J. Physique, 6, 21 (1916); Bull. Soc. d'en. Ind. 
Nat., 118, 92 (1919). 

* "The Chemistry of the Secondary Batteries of Plante and Faure," MacMillan, 1883. 

For a discussion of this reaction see also Dolezalek "The Theory of the Lead 
Accumulator," Translated by Von Ende. 

99 



loo 



M. KNOBEL. 



mol of sulfuric acid should be used for every two faradays on 
discharge, instead of two mols, as Gladstone and Tribe's theory 
requires. Fery supports his theory by the claims that the higher 
oxide of lead can be shown to exist on the fully charged plate 
by chemical analysis ; that lead peroxide will not give the potential 
of the storage battery anode ; and that only one mol of sulfuric 
acid per two faradays is actually used on discharge. The careful 
experiments of Maclnnes, Adler and Joubert^ cast considerable 
doubt on the first two of these claims. They found by analysis 
that the material on the positive plate coincided closely in composi- 
tion with lead peroxide. They also found that PbO, formed 
chemically and electrochemically on a platinum sheet gave the 
same electromotive force in sulfuric acid as the storage battery 
anode, contrary to the experiments of Fery. 



Table I. 



Amp. 


Time of discharge in hr. 


* 


5 


6 


1.40 


4 


9 


1.48 


3 


14 


1.56 


2 


24 


1.69 


1 


59 


1.79 



In regard to the last mentioned claim of Fery, existing data are 
at variance and are quite inconclusive. Maclnnes, Adler and 
Joubert found that a quantity of sulfuric acid between one and 
two mols per two faradays is used on discharge, the values vary- 
ing from 1.34 to 1.79 mols. W. Kohlrausch and Heim" conclude 
that 2 mols per two faradays are used, but their work is of doubt- 
ful accuracy. Scheneck and Farbaky^ find on the average 1.23 mols 
for the same quantity. The work of Pfai¥^ in this connection is 

= Trans. Am. Electrochem. Soc, 37, 641 (1920). 

• Electrotechnische Zeit., 10, 327 (1889). These authors used a hydrometer for 
the specific gravity determinations and no mention is made of temperature control. 
^ Dingler's Polytech. Jour., 257, 357 (188S). 
8 Centralblatt fur. Accumulatoren, 11, 73, 173 (1901). 



THE REACTION'S OF THE LEAD STORAGE BATTERY. lOI 

the most useful, in that he has taken into account the other 
variables which might affect the quantity of HoSO^ used. He 
determined the quantity of acid used per two faradays (which 
will hereafter be designated by (/>) at successive intervals during 
the course of a single discharge, and also during several discharges 
at different current densities. The latter data are reproduced in 
Table I. 

These figures are significant, showing as they do how greatly <^ 
varies with the current. The tendency of <^, as seen best from a 
curve, is to approach, at sufficiently small current densities, the 
theoretical value two, required by the Gladstone and Tribe equa- 
tion. On account of the importance of this point in determining 
which reaction takes place in the battery it was thought desirable 
to ascertain whether ^ would not be found equal to 2 at very small 
current densities. 

EXPERIMENTAL. 

The first experiments were made with a positive and two nega- 
tive pasted plates^ of the following specifications : 

Dimensions, 14.5 cm. wide, 12.5 cm. in height and 0.25 cm. 
thick ; weight of unpasted grid 225 g. ; weight of dry pasted posi- 
tive 366 g. ; and of dry negatives 347 g. ; rated capacity 20 amp.-hr. 
They were put in a jar of such a size that about 1,000 g. of elec- 
trolyte just covered the plates. A rubber cover was used on the 
cell to prevent loss of electrolyte. A copper coulometer was used 
to determine the number of faradays passed. The specific gravity 
determinations were made at 25° C. with a 10 cc. pycnometer and 
the percentages of sulfuric acid were interpolated from the tables 
of Landolt and Bornstein. From one-half to two hours, with 
occasional stirring, was allowed for the electrolyte to become 
uniform in composition after a run, the longer time being for 
rims at higher currents. All measurements were made at a 
temperature of 26° C. ± 2°C. 

The results on these pasted plates are listed in the first six runs 
of Table II, the headings of which are self-explanatory. In every 

» These plates vere obtained through the kindness of the .American Storage Battery 
Co., manufacturers of the "Harvard" battery and are designated by them as Type A. 



I02 



M. KNOBEL. 



case the values of <f> were found approximately equal to two/° 
including the run at 10 amperes, which is five times the rated 
current for the cell. The high values of (f> in the first two runs 
are probably due to local action of the acid on the new grids. The 
deviations in the calculated value of cj> may be as large as 3 per 
cent, for although the density determinations are comparatively 
precise, the quantity of acid consumed is determined as the 
dift'erence in two large numbers and the percentage error in the 
difference becomes large. 

Table II. 
Consutnption of H^SO^ in Storage Battery Discharge 







Time 






Weight 














of dis- 


Density 


of acid 


of 


Weight 




Weight 




Run 


Current 
amp. 


charge 

hr. 

(ap- 
prox). 


begin- 
ning 


end 


trolyte 

g. 
(begin- 
ning) 


of 

HaSO* 

used 


Faradays 


H2SO4 

theo- 
retical 


* 


1 


0.10 


53.0 


1.1245 


1.1106 


986 


21.1 


0.2018 


19.79 


2.13 


2 


0.50 


20.0 


1.1299 


1.1031 


950 


39.0 


0.3719 


36.47 


2.14 


3 


1.0 


16.0 


1.1394 


1.1000 


967 


58.3 


0.5905 


57.91 


2.01 


4 


2.0 


4.0 


1.1440 


1.1230 


957 


31.2 


0.3159 


30.98 


2.01 


5 


5.0 


2.5 


1.1465 


1.1187 


949 


41.8 


0.4218 


41.37 


2.02 


6 


10.0 


0.7 


1.1872 


1.1772 


1400 


21.0 


0.2093 


20.55 


2.04 


7 


0.5 


10.0 


1.1775 


1.1679 


920 


14.5 


0.1760 


17.26 


1.68 


8 


0.5 


12.5 


1.1679 


1.1561 


906 


18.2 


0.2319 


22.75 


1.60 


9 


0.5 


5.0 


1.1561 


1.1537 


888 


3.5 


0.0724 


7.11 


0.98 


10 


0.5 to 
0.1 
0.1 


16.0 


1.1537 


1.1522 


882 


2.1 


0.0695 


6.80 


0.62 


11 


65.0 


1.1893 


1.1741 


941 


23.0 


0.2445 


24.00 


1.92 



Run 8 is a continuation of run 7; run 9, of run 8; run 10, of run 9. 



Experiments were made next with a Plante type positive^^ 
(Manchester plate) of the same superficial area, with the same two 
pasted negatives. The results on this plate are listed in Runs 7 to 
11 of Table II. Runs 7 to 10 are for successive periods in a single 
discharge, and it is seen that the quantity of acid used decreases 

•" <<> was calculated from the equation : 

_ WP (a — b) 
* ~ C (49 - 40b) 
in which W is the weight in grams of the electrolyte before the run, F equals 
96,500, C is the number of coulombs passed, a and b are percentages (x 0.01) of 
HjSOi before and after the run respectively. 

'1 Maclnnes, Adler and Joubert used a Manchester plate. 



THE REACTIONS OF THE LEAD STORAGE BATTERY. I05 

constantly as the discharge continues. Run 11 is at a lower cur- 
rent density than Runs 7 to 10 and for the same part of the dis- 
charge as Run 8. It is seen that the value of </> (1.92) at the 
lower current is much nearer to 2 than at the higher current, which 
confirms the results of Pfaff previously given. It was thought 
unnecessary actually to discharge the Manchester plate at a 
current low enough to make <f> equal to 2 since the experiments on 
the pasted plate showed that 2 is the correct value. 

DISCUSSION OF RESULTS. 

The explanations which have been suggested for the small 
amount of acid used on discharge, with the exception of the 
theory of Fery, are based primarily on the supposition that there 
exists a lack of sulfate ions in the pores of the positive plate. The 
present results confirm this hypothesis. On the pasted plate the 
material is so porous and the reaction proceeds to such a small 
depth that a large concentration difference of acid cannot exist. 
While the sulfate ions migrate out of the plate, they are easily 
replaced by dilifusion. 

The construction of the ^Manchester plate, with the inserted 
lead ribbon buttons, however, is such as to produce ideal condi- 
tions for the depletion of sulfate ions in the inner parts of the plate. 
The acid can diffuse only very slowly into the narrow and deep 
channels of the button. This effect should become greater as the 
discharge continues and the reaction proceeds farther into the 
plate and the experimental values of </> do in fact decrease as the 
discharge continues as seen in Runs 7 to 10. At lower current 
densities the migration outward of the ions is less and the time 
for diffusion of acid back into the plate is greater so that the con- 
centration decrease in the pores should be less than at higher cur- 
rents. The high value of <f> in Run 11 confirms the above state- 
ment. It is probably only on the Manchester or similar plate 
which contains such deep channels that the above effect will be 
observed. 

Just what reaction takes place when less than the theoretical 
amount of acid is used is still somewhat uncertain. It is probable 



I04 



DISCUSSION. 



that a mixture of lead oxide and lead sulfate is formed, varying 
in proportions as the lack of sulfate ions becomes greater. When 
this condition exists the free energy of the reaction will be less 
and the voltage of the cell should become less. On the pasted 
anode, the voltage was constant until near the end of the discharge, 
when it dropped rapidly. With the IManchester plate, however, the 
decrease in voltage during discharge was much more gradual, and 
a large fraction of the discharge (Run 10) was obtained after the 
voltage had fallen below 1.7. A part of this decrease in voltage 
is due, of course, to the decrease in acid concentration, and part to 
the increasing resistance of the cell on discharge, but a part may 
be due to the decreased free energy of the reaction. 

SUMMARY. 

It has been found that under proper conditions the amount of 
acid used on discharge of the lead storage battery corresponds to 
that required by the Gladstone and Tribe theory. The evidence in 
favor of the latter theory is thus completed and the theory pro- 
posed by Fery appears untenable. 



DISCUSSION. 



Helen Weir^ : May I ask Dr. Knobel what evidence he has 
that any other compound is formed than lead sulfate, as a part 
in the discharge? 

M. Knobel: From the number of faradays passed through the 
battery, the amount of lead peroxide reduced is known, but less 
acid is used than there would be if only lead sulfate were formed. 

Helen Weir: As I understand no analyses have been made; 
is there not a possibility of an experimental error there? 

M. Knobel: Since the value of <f> came out as low as 0.6, 
the percentage error would have to be as large as 70 per cent, 
which is improbable. 

1 Union Carbide and Carbon Res. Lab.. Long Island City, N. Y. 



THE REACTIONS OF THE LEAD STORAGE BATTERY. 1 05 

Helen Weir: You will remember Dolzalek substantiated the 
double sulfate theory by thermo-dynamic relations, and those 
relations need no modification to support the theory. 

M, Knobel: I do not see that thermodynamic calculations 
have anything to do with the present question; it is a matter of 
Faraday's Law and the quantity of materials used. 

Helen Weir: But in the slow discharges where you have 
the most ideal condition for diffusion and can get the most 
accurate determination, you come nearest to finding that you do 
use two mols per faraday. Do you not think that this is evidence 
that a lead sulfate is formed rather than an intermediate or 
additional compound? 

On your lower rates of discharge your sulfate is formed 
throughout the pores of the plate and into the interior, so that 
you can get an ideal condition for your determination, but on a 
high rate where you have it formed on the surface, it is possible 
that you may have sulfuric acid trapped in the pores which 
diffuses out very slowly. 

M. Knobel : In answer to that point I may say that when the 
density determination was made one hour after the run and then 
again two hours later, there was found to be no appreciable 
difference. 

Helen Weir: How do you explain recuperation then? At 
any high rate of discharge you can get remarkable recuperation 
in two hours, due presumably to diffusion of acid. 

M. Knobel: That is in the voltage. 

Helen Weir: Ampere-hour capacity also. It is an inter- 
esting phase of the storage battery subject, and I would like to 
see some more work on it. 

M. Knobel (Communicated) : A further point may be men- 
tioned in regard to Mrs. Weir's question of the possibility of 
experimental error. If acid were trapped in the pores of the 
plate and came out slowly, a density determination made a long 



I06 DISCUSSION. 

time after the run should be larger than one made just after the 
run and would therefore result in a still smaller value oi eft . 

Recuperation may be explained by diffusion of the acid back 
into the plates. The first result of this would be to build up the 
voltage. The capacity would then increase, but only because the 
voltage has increased, the capacity being limited by an arbitrary 
low voltage. 



A patter presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 3, 1923, Dr. Wm. G. Horsch 
in the Chair. 



ELECTROLYTIC AND CHEMICAL CHLORINATION OF BENZENE.' 

By Alexander Lowy and Henry S. Frank. ^ 

Abstract. 

One of the processes to which the electrolytic method applies is 
the chlorination of benzene, and it seemed advisable to investigate 
this reaction because (1) only a limited amount of work has been 
done on this subject, (2) reports in the literature are often 
contradictory, and (3) investigation of this kind might throw 
additional light on the mechanism of chlorination. 



HISTORICAL. 

A considerable amount of research work has been done on the 
chlorination of benzene. A number of important references for 
the chlorination of benzene by the chemical method, under variable 
conditions, are given below.^ 

Concerning chlorination of benzene by the electrolytic method, 
Miihlhofer* stated that benzene is not appreciably affected by elec- 
trolytic chlorine. Miihlhofer found, however, that when 20 g. 
toluene was stirred vigorously into 250 cc. cone. HCl, and the 
mixture electrolyzed, a good current yield of chlorotoluene was 
obtained (30 per cent ortho, 70 per cent pasa). The addition of 

' Manuscript received January 26, 1923. 

* Contribution from the Dept. of Chemistry, University of Pittsburgh, Pittsburgh, Pa. 
»Pogg. Ann. 29, 231 (1833); 31, 283 (1834); Ann. chim. 26, 59 (1834); 63, 41 

(1836); Comptes rendus des travaux de chimie (1849) 429; Proc. Royal Soc. 7, 18. 94 
(1854); J. C. S. 15, 41 (1862); 16, 76 (1863); Ann. chim. (4) 15, 186 (1868); Ber. 8, 
1400 (1875); Ann. 225, 199 (1884); Compt. rend. 127, 1,026 (1898); 126, 1212 (1898); 
170, 1319, (1920); Bull. soc. chim. 29, 283 (1903); J. Soc. Chem. Ind. 35, 1130 (1916); 
Chem. Soc. Proc. 24, 15-16 (1908); Germ. pat. 219,242; U. S. Pat. 1,180,964; U. S. 
Pat. 1,189,736, and corresponding foreign patents; Compt. rend. 170, 319 (1920); J. 
Am. Chem. Soc. 36, 1007-11 (1914). 

♦ Dissertation "Uber die Einwirkung elektrolytisch erzeugter Halogene auf Organ- 
ischen Verbindungen." Technische Hochschule, Munich, (1905). 

I07 



I08 ALEXANDER IvOWY AND HENRY S. FRANK. 

iodine did not influence the products in nature or amount. Benzyl 
chloride was not formed. 

Schluederberg^ electrolyzed benzene in ether saturated with 
ZnClo, removing 76 to 80 per cent of the chlorine from inorganic 
combination. When benzene was floated on a layer of Oettel's 
solution (160 g. NaCl, 140 g. H0SO4 made up to 1 liter with water) 
and electrolyzed, the rotating anode being entirely in the benzene 
layer, an efficiency of only 2.29 per cent was obtained. Analogous 
experiments with toluene gave efficiencies ranging from 4.07 to 
38.25 per cent. Of the chlorine acting, 76 to 96 per cent substituted 
in the ring and the rest in the side chain. 

Van Name and Maryott^ electrolyzed benzene in a glacial acetic 
acid solution of LiCl, and found that chlorination took place. It 
also took place, however, when chlorine was bubbled through the 
solution and electrolysis in addition to this bubbling produced no 
added effect. 

Fichter and Glanzstein^ used glacial acetic acid to prepare a 
homogeneous solution containing benzene and concentrated aque- 
ous HCl. Electrolysis of this solution gave, under various condi- 
tions, chlorobenzene, p-dichlorobenzene, sym-tetrachloro and hexa- 
chloro benzene and in addition pentachlorophenol and chloranil. 
The relative amounts of these substances present in the product 
depended regularly upon the current density employed, (in addi- 
tion to other determining conditions, such as temperature) which 
indicates that an electrochemical reaction was taking place. 

Neminski and Plotnikow* electrolyzed the molecular compound 
AlBrg . SCeHg, and observed that the hydrocarbon separated at 
the cathode, and bromination took place at the anode. 

Some additional light on whether or not the chlorination is elec- 
trochemical is shown by the work of Cohen, Dawson and Cros- 
land.^ They electrolyzed toluene with a carbon anode over a layer 
of cone. HCl. As in Schluederberg's later work, substitution was 
largely in the ring. When, however, chlorine was bubbled 
through the same mixture under the same conditions, substitution 
was almost entirely in the side chain. 

»J. Pliys. Chem. 12, 595 (1908). 

«Am. J. Sci. 35, 130-70 (1913). 

'Ber. 49, 2473-89 (1916). 

«J. Russ. Phys. Chem. Ges. 40, 391-96 (1908). 

*J. Chem. Soc. 87, 1034 (1905). 



THE CHLORINATION OF BENZENE. I09 

THEORETICAI,. 

The work described in the references cited above seems to indi- 
cate that in the absence of carriers, chlorine does not substitute 
for hydrogen in benzene, and most text books make this, or an 
equivalent statement. They then define a carrier as a substance 
which catalyzes the substitution of halogens into the ring in aro- 
matic hydrocarbons. Most lists of carriers include 1, Fe, FeClg, 
SbCl3, SbCIs, M0CI5, Al or AICI3, PCl^, S, ZnCl^, and Sn. For 
other halogens the corresponding halides are used. 

The mechanism of the action of carriers seems to be fairly 
well agreed upon; the carrier forms an addition compound with 
the halogen, which it then liberates in a more active state than 
before. This view is supported by the fact that benzene can be 
chlorinated, for instance, by ICl, ICI3, FeCL, SbClg, M0CI5, etc., 
in the absence of any free chlorine. The function of the chlorine 
in these processes seems therefore to be regeneration of the original 
compound (ICI3, etc.). 

This concept of the mechanism of chlorination has been 
extended by Schluederberg^" to include electrolytic chlorination. 
as follows: Benzene is chlorinated by the action of negatively 
charged CI', and any source of negatively charged chlorine will 
therefore act as a chlorinating agent. He points out that each of 
the carriers mentioned dissociates, furnishing a negative chlorine, 
as: 

ICl -> P -f CI- 
FeClg -» FeCla + Cl- 
aud so on. Moreover, the fact that electrolytic chlorine may be 
considered negatively charged explains why benzene can be chlori- 
nated by electrolytic methods. 

According to another theory, however, halogens that substitute 
in the nucleus in aromatic compounds bear a positive charge. This 
is derived by Fry" from his electronic conception of the structure 
of benzene, and his argument is that each of the substances men- 
tioned as carriers is a possible source of positive halogen. He 
also points out that in the case of toluene, the presence of mois- 
ture promotes substitution in the ring, anhydrous halogens, in the 

"•J. Phys. Chem. 12, S93, (1908). 

11 Fry "Electronic Conception of Valence." 



no ALEXANDER LOWY AND HENRY S. FRANK. 

absence of carriers, tending to substitute in the side-chain. He 
suggested the following mechanism to explain this: the chlorine 
(for instance) first reacts with the water 

CI2 +H,0 ±5 HCl + HOCl 

The HOC^ then acts as a source of positive chlorine which 
replaces a positive hydrogen in the benzene : 

H" 



C 



+ 



H^C C= 



H^ + HO' 



-CI 
Cl^ > I I + H,0 



H^C^ /C^ H" 
C^ 



H' 



In this as in the ordinary interpretation of the reaction, half the 
original chlorine is converted to HCl. 

Work done in the course of this investigation confirms Fry's 
hypothesis that water may act as a halogen carrier, as far as 
chlorine is concerned. With chlorine and benzene in the presence 
of water, substitution was obtained. Under identical con- 
ditions, with anhydrous materials, no substitution took 
place, but a considerable amount of benzene hexachloride was 
produced. As the results with water were duplicated when light 
was excluded from the system, there was obviously no photochemi- 
cal action, and the eftect was due entirely to the water, which 
probably acts as suggested by Fry. 

A point in favor of this theory is the fact that the yield was 
nearly doubled by allowing the charge to stand overnight at the 
conclusion of the experiment. The additional chlorination here 
was undoubtedly effected by the chlorine that had been in solu- 
tion. 

According to the above, the electrolytic chlorination cannot be 
an electrochemical phenomenon since electrolytic chlorine at the 
moment of liberation is negative. According to Fry's hypothesis, 
the chlorination in the electrolytic cell would have to be called a 
secondary reaction depending upon the previous liberation of 



THE CHLORIXATIOX OF BENZENE. Ill 

molecular chlorine, Clj, and possible only on account of the water 
present, the action being, 

CI2 + H2O ~"^ HCl ^ HOCl 



+ HOCl ^ i j + H2O 



If, however, the chlorination is not electrochemical, it is difficult 
to explain the fact that the electrolytic reaction furnishes some 
more highly chlorinated products, which the non-electrolytic reac- 
tion does not give under the same conditions. Indeed, the latter 
fact points strongly to direct anodic depolarization as the 
explanation of the electrolytic process. 

It would appear that the true explanation of what takes place 
in the chlorination of benzene must be sought further, and it is 
not hard to understand the disagreement among the men who 
have chlorinated benzene electrolytically, as to whether the phe- 
nomenon is chemical or electrochemical : the results obtained point 
to both conclusions. 

The addition of iodine as a carrier to the system where aqueous 
chlorination was taking place increased the extent of the chlorina- 
tion, but not to anything like the degree in which it would have 
done so, had the system been anhydrous. 

EXPERIMENTAL PART. 

(A) Electrolytic Methods. 

The electrolytic experiments were conducted in the apparatus 
represented in Fig. 1. Particular attention is called to the water 
seal arrangement, and to the glass tube by which the porous cup 
cathode cell was suspended. The former made it possible to intro- 
duce or remove a charge easily and quickly without interfering 
with the stopper, which was permanently set up and insured an 
entirely gas-tight system. The glass tube conducted the hydro- 
gen from the cathode directly to the outside atmosphere, prevent- 
ing the formation of an explosive mixture inside the cell. 

An experiment was made as follows : 750 cc. of 12 per cent 



112 



ALEXANDER LOWY AND HENRY S. FRANK. 



HCl (sp. gr. 1.06) and 75 cc. of pure benzene were placed in the 
beaker (4 on Fig. 1), and fitted into the cell. The mixture was 
agitated vigorously by means of a bell-type stirrer, and current 










K) 4- W' >o' r>' a) 



> 




i "^J 
^ 



V 



°- * t; "^ "0 *: 



< ^j CD ^ 

— • /U K) 't^ <0 



d t 



was passed. Under the conditions of agitation the mixture 
resembled an emulsion. 

A stream of air was maintained through the system by means 
of an aspirator bottle. The air inlet in the stopper is not shown. 



THE CHLORINATIOX OF BENZENE. I l3 

but was equipped with a soda-lime tube through which the air 
passed before entering. The possible constituents of the vapor 
passing up the condenser were chlorine, hydrogen chloride, ben- 
zene vapor, oxygen, nitrogen, hydrogen (perhaps by diffusion 
through the porous cup), water, CO2, CO. The two latter were 
formed by anodic oxidation of the benzene. The oil-tube, (8), 
contained heavy lubricating oil cooled to 0° C, the function of 
which was to absorb the benzene vapor. Tube (9) contained 
aqueous KI. The water removed any HCl in the vapors, and the 
KI completely removed the chlorine. As the experiment con- 
tinued, this solution gradually colored up to a deep red. The U 
tube (10) contained NaOH solution, which absorbed COg. The 
NaOH was about 0.5 A'', of undetermined strength, and was always 
present in excess. At the conclusion of the experiment the con- 
tents of the U tube was washed into a beaker, and the solution 
neutralized to phenolphthalein with HCl of undetermined 
strength. Two drops of methyl orange were then added, and the 
solution titrated with standard HCl to a fairly strong end-point. 
The hydrochloric acid used here was equivalent to half the CO2 
evolved during the electrolysis. 

The remaining constituents of the gas, CO, O2, H, and Nj were 
passed over hot CuO in tube (11), where the CO was oxidized 
to COj. This was absorbed by an excess of standard Ba(OH)2 
in the wash-bottle (12), and the excess back-titrated to phenol- 
phthalein with standard oxalic acid. This gave a figure for the CO 
produced by the electrolysis. The use of two oil-absorbing tubes 
did not always prevent the escape of some benzene vapor, which 
was then burned over the CuO and determined as CO. For this 
reason the CO figure is not always trustworthy. It will be noted 
that a possible escape of HCl or Clg into the NaOH in tube (10) 
could not harm the CO2 determination as long as sufHcient NaOH 
was present to be alkaline to phenolphthalein at the end of the 
experiment, which was always the case. It is reasonably certain, 
however, that no Clj or HCl did escape in this way. 

The cell was kept at the desired temperature by circulating 
water from the constant temperature bath through the glass spiral 
coil (6). Control within one degree was obtained in this way, 
and it was possible to run at any temperature between 12° and 
70° C. 



114 ALEXANDER LOWY AND HENRY S. FRANK. 

After an experiment was completed, the charge was allowed 
to stand over night in place, after which the layers w^ere separated 
and the aqueous layer extracted once with benzene. The benzene 
extract was added to the oily layer and rendered alkaline, made 
up to about 500 cc. with water, and steam distilled. The distillate 
was separated, and the lighter oily layer, consisting of benzene 
and substituted chlorobenzenes subjected to fractional distillations 
three times, the fractions collected being below 90°, 90-120°, 120- 
135°. The latter fraction contained the chlorobenzene. A trace 
of charred residue was left in the distilling flask although the dis- 
tillation was made from an oil bath. 

The residue from steam-distillation was extracted twice with 
ether, and the residue left on evaporating off the ether, weighed 
as the alkali-insoluble product. It consisted of more highly chlori- 
nated products. The residue from the ether extraction was acidi- 
fied, and again extracted twice with ether. The residue remain- 
ing this time on evaporating ofif the ether was weighed as the 
alkali-soluble product. It was a tarry mass with a strongly 
phenolic odor. 

A number of electrolytic experiments were performed under 
difterent conditions, giving different results. The purpose of 
each experiment, its results and conditions are given in Table I. 

(B) Non-Electrolytic. 

The first non-electrolytic experiments were conducted in the 
same apparatus, the chlorine being bubbled in through a capillary 
in contact with the platinum anode. In order to discover whether 
the results were in any way due to the presence of the platinum, 
or of the alundum porous cup, etc., the rest of the purely chemi- 
cal experiments were made in a glass bottle containing nothing 
but a glass inlet tube, a glass outlet tube, and a glass bell stirrer. 
The latter was also equipped with a mercury seal, but precautions 
were taken to prevent contamination of the charge with mercury. 
The chlorine was generated by dropping an excess of HCl on a 
weighed amount of KMnCj. It was bubbled through water to 
remove HCl, and in one case through cone. H^SO^ to remove 
moisture. 

The charge was the same as in the other series, except that in 



THE CHLORINATION OF BENZENE. 



115 



Table I. 
Experiments in the Electrolytic Chlorination of Benaene. 



Expt. 
No. 



V 

2- 

3 

43 

5 

7 

8 

95 

10 
11 
12 

13" 
14^ 
15' 
16" 



Factor 




Studied 


Amp. 




5.2 


Temp. 


5.2 


Temp. 


5.2 


Temp. 


5.2 


Temp. 


5.2 


Temp. 


5.2 


Stir'g 


5.2 


Stir'g 


5.2 


Temp. 


5.2 


Carrier 


5.2 


Stir'g 


5.2 


Carrier 


5.2 


Anolyte 


5.2 


CD. 


2.6 


CD. 


8.1 


Stir'g 


5.2 



Anode 

amp. c. d. 

per 

sq. dm. 



Volts 



116-120 
116-120 
116-120 
116-120 
116-120 
116-120 
116-120 
116-120 
116-120 
116-120 
116-120 
116-120 
116-120 
58-60 
171-180 
116-120 



8.0 
8.7 
9.4 
7.4 
8.0 
10-11 
7.6 
8.0 
6.6 
6.4 
6.4 
8.0 
12-12.4 
7.0 
13.2 



i Curent 

passed 
amp. hr. 



16.2 
16.2 
16.2 
16.2 
16.2 
16.2 
16.2 
16.2 
16.2 
16.2 
16.2 
16.2 
16.2 
16.2 
16.2 
16.2 



' Anolyte 


Temp. 


per cent. 


°C. 


12HC1 


30 


12HC1 


15 


12HC1 


20 


12HC1 


55-60 


12HC1 


40 


12HC1 


12-15 


12HC1 


50 


12HC1 


30 


12HC1 


70 


12HC1 


70 


12HC1 


70 


12HC1 


20 j 


20 NaCl 


50 ' 


12HC1 


20 i 


12HC1 


20 1 


12HC1 


20 ' 



Stirring 



500 r.p.m. 
500 r.p.m. 
500 r.p.m. 
500 r.p.m. 
500 r.p.m. 
500 r.p.m. 
300 r.p.m. 
300 r.p.m. 
500 r.p.m. 
500 r.p.m. 
300 r.p.m. 
300 r.p.m. 
300 r.p.m. 
300 r.p.m. 
300 r.p.m. 
300 r.p.m. 



Expt. 
No. 




Benzene 


Distillate 


Alkali 


Alkali 






Carrier 


used 


lac-iss" 


insol. 


sol. 


CO2 


CO 






g. 


g. 


g. 


g. 


g. 


g. 


r 


None 


65 


14.0 


0.04 


0.16 


0.232 


0.056 


2- 


None 


65 


13.0 


0.01 


0.19 


0.123 


0.048 


3 


None 


65 


13.5 


0.04 


0.14 


0.13 


0.074 


4' 


None 


65 


17.5 


0.20 


0.18 


0.23 


0.10 


5 


None 


65 


16.3 


0.02 


0.07 


0.20 


0.15 


6* 


None 


65 


11.8 


0.01 


0.07 


0.119 




7 


None 


65 


19.2 


0.13 


0.22 


0.21 


0.12 


8 


None 


65 


17.5 


0.03 


0.16 


0.176 


0.12 


9^ 


None 


65 


9.6 


1.34 


1.87 


0.25 




10 


1 g.l2 


65 


11.8 


0.53 


0.38 


0.29 


0.16 


11 


None 


65 


12.4 


0.09 


0.35 


0.31 


0.15 


12 


1 g.l2 


65 


18.6 


0.16 


0.18 


0.13 


0.12 


13' 


None 


65 


7.Z 


0.66 


0.66 


0.21 


0.19 


14^ 


1 g.l2 


65 


10.7 


0.14 


0.13 


0.209 




15' 


1 g.l2 


65 


15.82 


3.28 


0.50 


0.10 


0.146 


16" 


None 


65 


15.8 


... 









1 Oily layer was orange color. 
^ Oily layer lemon yellow. 
' Oily layer orange red. 
■* Yellow oily layer. 
° Red oily layer. 



" Color was pale green. 

^ Expt. conducted twice as long as others. 

* Run two-thirds as long as others. 

* Worked only for Chlorobenzene. 



The anode was in every case a platinum wire loop of 4.5 sq. cm. area. 
Remarks as to color, etc., are made only in typical instances, and are 
indicative of a general trend. 



II6 



ALEXANDER LOWY AND HENRY S. FRANK. 



most cases distilled water replaced the hydrochloric acid. The 
chlorine was bubbled through at a uniform rate and the charge 
was well stirred. The product of an experiment after standing 
over night, was separated, and the oily layer washed free of 
chlorine with XaOH. It was then fractionated for chlorobenzene 



Table II. 
Non-Electrolytic Chlorination of Benzene. 







Ben- 


Other 


Distillate 




Expt. 
No. 


Factor 
studied 


zene 

used 

g- 


com- 
ponent 


120-135' 


Remarks 


18 


Chemical 


65 


12 per 


22.6 


Experiment conducted in 




action 




cent HCl 




electrolytic cell. Excess 
CI2 used. Qualitative ex- 
periment. 


19 


Quantitative 


6,S 


12 per 


19.8 


Same as No. 18 except CU 




relations 




cent HCl 




generated from 19 g. 
KMn04 (equivalent to 
16.2 amp. hr.) 


20 


Foreign 


65 


12 per 


20.6 


New apparatus used. Noth- 




material 




cent HCl 




ing present except react- 
ants. Same amt. CU as 
in No. 19. 


21 


Function 
of HCl 


65 


Dist. H2O 


12.7 


Worked up immediately in- 
stead of standing overnight 
as in all other expt. -f- 
same CI2. 


22 


Effect of 
standing 


65 


Dist. H=0 


20.4 


Same as No. 21, but stood 
overnight. 


23 


Effect of 
light 


65 


Dist. H2O 


21.4 


Same as No. 22, except that 
light was excluded. 


24 


Effect of 


65 


Materials 


. , 


No substitution took place. 




moisture 




were an- 
hydrous 




Benzene hexachloride was 
obtamed. Same amount 
of CI, used. 



just as before. There were no higher chlorination products, 
either alkali-soluble or alkali-insoluble formed, or at most, mere 
traces. 

The results of the various experiments as well as their pur- 
poses, and the conditions under which they were made, appear in 
Table II. 



THE CHLORINATION OF BENZENE. II7 

DISCUSSION OF RESULTS AND SUMMARY. 

1. It is possible to chlorinate benzene by stirring it in with 
aqueous HCl and electrolyzing. Aqueous NaCl can also be used. 

2. The yield of chlorobenzene increases with increase of tem- 
perature up to 60°. 

3. The yield of chlorobenzene is affected by the rate of stirring. 

4. The introduction of iodine as a carrier increases the yield of 
chlorobenzene. 

5. The amount of higher chlorinated products formed increases 
in general with rise in temperature. 

6. The amount of benzene decomposed to COj by anodic oxida- 
tion increases with the temperature. 

7. Increase in current density rapidly increases the alkali-in- 
soluble product. 

8. Water acts as a carrier in the chemical chlorination of ben- 
zene. 

9. No substitution takes place when dry chlorine is passed 
into dry benzene. However, chlorine forms addition products of 
the type of benzene hexachloride. 

10. Miihlhofer^^ states that the addition of iodine as a cata- 
lyzer does not alter the course of the electrolysis. The above 
experiments show that under the conditions cited, iodine seems 
to catalyze the chlorination. 

11. A new form of apparatus was devised for this type of 
electrolytic work. 

12. A preliminary series of experiments was conducted to 
study the electrolytic chlorination of benzene. A more detailed 
study of this process under variable conditions, as well as elec- 
trolytic bromination and iodination, will be reported in subsequent 
papers. 

" Dissertation cited, quoted in Haber and Moser "Die elektrolytischen Prozesse der 
organischen Chemie." p. 97. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 3, 1923, G. B. Hogaboom in 
the Chair. 



NOTES ON THE ELECTRODEPOSITION OF lRON\ 

By Harris D. Hineli.ve.^ 

Abstract. 
Experiments were carried out to determine the type of plating 
bath that would give good deposits of iron on rubber. Particular 
attention was given to baths of high "throwing" power. \''arious 
formulas were tried out. A saturated bath of ferrous and calcium 
chlorides, containing chromous chloride and hydroquinone as 
reducing agents, gave the best results. Further investigation is 
encouraged. [A. D. S.] 



The problem presented was that of depositing a substantial 
thickness of iron onto rather irregularly shaped rubber articles, this 
involving a process for preparing a conducting coating, a plating 
bath which would give good heavy deposits, in thicknesses up 
to 12.5 mm. (y^ in.), and have a high throwing power to ensure 
filling the crevices. The conducting coating on the rubber was 
easily obtained by varnishing it, and then brushing in graphite, 
repeating the application of graphite at intervals until the varnish 
was too dry to take on any more. 

The ferrous ammonium sulfate bath suggested by D. R. 

Kellogg^ was tried out, but found to be unsatisfactory, as it is too 

easily rendered useless by organic extractives from the rubber. 

The deposit was badly pitted. Kellogg, too, records the failure 

of his bath when organic compounds entered it. 

The best summary of work done on iron plating baths is that 

by Mr. W. E. Hughes.* From this summary we concluded that 

' Original Manuscript received Sept. 3, 1922. 

2 Pittsburgh Park, Pittsburgh, Pa. 

3 Trans. Am. Inst. Min. and Met. Eng., Feb., 1922. 

* Trans. Am. Electrochem. Soc, 40, 185, et seq., (1921). 

119 



I20 HARRIS D. HINELINE. 

the Fisher-Langbein, ferrous calcium chloride bath would 
probably be the most promising for our problem. However, this 
bath caused serious pitting and corrosion on both iron and rubber 
cathodes. A simple ferrous chloride bath, (150 g./L.) was 
equally bad, suggesting that the trouble might be 
due to the presence of ferric chloride. A bath made up of 
150 g./L. of ferrous chloride and 100 g./L. of sodium acid sul- 
fite to insure complete reduction of all the iron, gave a very 
good deposit for several days, reaching a thickness of about 0.24 
mm. (3/32 in.). Corrosion then began, due partly to exhaustion 
of the sulfite, and partly to high acidity. 

No mention is made in Mr. Hughes' paper of any trials of a 
bath made up of ferrous sulfite. A solution was therefore pre- 
pared by treating a suspension of ferrous carbonate in water with 
sulfur dioxide. A solution containing about 50 g./L. of iron was 
obtained, probably present as ferrous acid sulfite. On electrolysis, 
no iron deposit was obtained, but instead, a thick mass of mate- 
rial at the cathode, which seemed to be a mixture of ferrous sul- 
fite and sulfide. The mass, on treatment with dilute acid, first 
evolving sulfur dioxide and then hydrogen sulfide, dissolved 
completely. 

Since the addition of the sulfite to the ferrous chloride solu- 
tion gave a good deposit it did seem that a reducing agent in 
the bath would improve conditions. A canvass of available 
reducing agents suggested hydroquinone as a possibility. A bath 
containing 250 g./L. of ferrous chloride, a little ferrous carbonate 
and 5 g./L. of hydroquinone gave a deposit free from corrosion 
and pitting. A solution of 150 g./L. of ferric chloride was then 
reduced with an excess of hydroquinone. The lower solubility of 
the resulting quinone caused it to crystallize out. 

The solution with its suspended crystals was then electrolyzed 
at a c. d. of about 2.7 amp./sq. dm. (25 amp./sq. ft.). It yielded an 
excellent deposit, free from corrosion and treeing, but very brittle, 
due probably to high acidity from the reduction of the ferric salt. 
Large gas bubbles were evolved at the cathode, but they did not 
produce gas pits. A solution containing 200 g./L. of ferrous 
chloride, 200 g./L. calcium chloride and 10 g./L. hydroquinone 
gave an excellent deposit, and after electrolysis over a period of a 



NOTES ON THE EIvECTRODEPOSlTlON OF IRON. 12 1 

month, during which a deposit 3 mm. (^ in.) in thickness was 
made, the bath was still working well. Anode corrosion had 
liberated considerable sludge, so the bath was filtered. The fil- 
tered bath again gave much trouble due to corrosion, but the addi- 
tion of 10 g./L. of hydroquinone restored the bath to good 
working condition. 

In plating baths a wide variety of addition agents, both organic 
and inorganic, is used. Glue, glycerine, gum arabic and dextrose 
were tried in a Fisher-Langbein bath containing hydroquinone, 
but all were rapidly destroyed, yielding a sludge and breakdown 
products which ruined the bath. In one case 20 g./L. of glue were 
added, giving a bath of such high viscosity that the hydrogen 
liberated at the cathode was held in place. The iron was deposited 
between the bubbles, resulting in a bulky deposit of fine iron 
crystals. 

Chromous chloride being a good reducing agent, a bath was 
made up containing 10 g./L. of it, and 200 g./L. each of ferrous 
chloride and calcium chloride. This gave a very good deposit at 
a c. d. as high as 8 amp./sq. dm. (75 amp./sq. ft.) even when 
continued over a period of a month, although some trouble was 
experienced with treeing. Manganous chloride gave a similar 
result, but required much larger quantities. Antimony, added as 
chloride, plated out before the iron; zinc was without eflfect. 

A bath containing, per L., 350 g. of ferrous chloride, 225 g. of 
calcium chloride, 20 g. of chromous chloride, and 5 g. of hydro- 
quinone, was chosen as having about the best proportion among 
its various constituents. This was used at a temperature between 
60 and 70° C. It showed no corrosion, no pitting, only a little 
treeing and fair metal quality. Deposits as thick as 12.5 mm. 
(1/2 in.) were made which had about the strength of a mediocre 
grade of cast iron. The individual crystals of metal were very 
large, some extending entirely through the deposit. 

In most of the trials made in search of a suitable bath flat rubber 
or iron sheets were used as cathodes. It was soon noticed that 
although rubber is a good insulator, a "strike" of deposited metal 
over its surface could be obtained without special preparation. A 
sheet of rubber simply suspended in the bath by a metal clamp, 
so that part of the clamp was submerged, would take a "strike'* 



122 HARRIS D. HINELINE. 

over its entire surface in a very short time. This fact seriously 
compHcated the problem of falling the grooves and crevices in the 
specimens. The plating bath we developed does not "throw" its 
deposit at all well, in fact none of the iron baths will "throw" as 
well as zinc and copper cyanide baths will. 

We were not able to prepare a conducting line with varnish and 
graphite at the bottoms of the crevices and keep the deposit on it. 
In a very short time the metal would strike over the entire rubber 
surface, whereupon it ceased to deposit in the crevices. Rubber 
being a good insulator, this was most unexpected. The physical 
character of the surface of the rubber or perhaps the interfacial 
tension between rubber and solution may account for the 
phenomenon. 

A variety of expedients were tried to overcome the difficulty. 
Small anodes placed within the crevices, so as to shorten the cur- 
rent path, were ineffective because of lack of anode area. Strongly 
charged shields, covering the projecting portion, showed possi- 
bilities, but an adequate insulating covering for the shields was 
not available. Anodes in contact with the projection forced the 
deposit into the grooves, but did not fill them to the bottom. Hard 
rubber shields to control the path of current flow worked, until 
the deposit was thick enough at some point to touch the shield, a 
strike then took place over the shield, and it got all the deposit. 
A rapid stream of electrolyte, impinging on the surface of the 
projection would keep the deposit oft of it, but the stirring of 
the solution was too great, and a knobby deposit resulted. 

It finally became evident that it would be necessary to cover the 
ejitire rubber surface with stopping oft* material ; a tung oil bak- 
ing varnish, lightly baked, was found to be adequate. Conducting 
lines were then put in the bottom of the crevices, and it was found 
that if the applied voltage did not exceed 0.45 volt the deposit did 
not creep, and the crevices could be filled completely before any 
metal deposited on the tops of the projections. With the crevices 
filled, a slightly higher voltage would cause the deposit to strike 
over the entire surface. An observation that should be recorded 
is the effect of various hydro-carbons on the bath. Saturated 
petroleum products, such as gasoline, kerosene, or machine oil, 
produce bad treeing of the deposit, even when present in exceed- 



NOTES OX THE ELECTRODEPOSITION OF IRON, 123 

ingly small quantities, while turpentine, in considerable quantity, 
is without effect on the deposit. 

The bath made up as first indicated worked reasonably well, but 
proved to be a little too dilute. Better results were obtained from 
a bath made up with equal parts of ferrous chloride and calcium 
chloride in such a quantity as to make the bath saturated at a 
temperature of about 30° C, to which was added about 20 g./L. 
of chromous chloride, and about 5 g./L. of hydroquinone. This 
bath worked best at a temperature of 60° to 70° C. Lower tem- 
peratures gave a poorer deposit, less strength and more inclusions, 
while higher temperatures showed rather too much evaporation. 
The material in the bath appears to be present in the form of a 
double salt of iron and calcium chloride in which the ferrous ion 
is much reduced in concentration. The solution is much lighter 
in color than the equivalent solution of ferrous chloride alone, 
and the salts crystallizing out are also much lighter in color than 
ferrous chloride crystals and different in crystal habit. 

It is of primary importance that the iron in the bath be kept 
in the ferrous condition. It is difficult to determine the 
amount of ferric iron in any given bath, but the permissible 
amount in a satisfactory bath is certainly below 1 g./L. and 
probably below 0.1 g./L. This low concentration of ferric 
iron may be maintained by the use of hydroquinone in the solution, 
in spite of the high partial pressure of oxygen at the surface of 
the solution, and in spite of oxygen liberated at the anode, 
when anode corrosion is less than 100 per cent. The hydro- 
quinone has a higher reduction potential than ferrous chloride, 
and a comparatively small concentration of it will keep the ferric 
iron content sufficiently low. The hydroquinone is oxidized to 
quinone, which, although not as soluble as the hydroquinone itself, 
is still somewhat soluble, so as to bring a low concentration to 
the cathode surface. The hydrogen, which was always liberated at 
the cathode to a certain extent, is taken up by the quinone to 
reform hydroquinone, thereby maintaining the hydroquinone 
content. 

The hydroquinone may be considered as a carrier of hydrogen 
from the cathode to the solution, thereby taking care of the hydro- 
gen which otherwise might form gas pits on the cathode. Likewise 



124 HARRIS D. HINEUNE;. 

the quinone may be considered as a carrier of oxygen from the 
anode, to obviate the difficulties due to less than 100 per cent anode 
corrosion. The hydroquinone and its oxidation product will 
remain in the solution without further destruction for a period 
of months. There appeared to be no electrode reactions which 
were sufficiently powerful to cause further reaction with the 
ring nucleus of the compound. A concentration of hydroquinone 
of 5 to 20 g./L. appears to be ample as long as anode corrosion 
efficiency does not get too low. It is possible that an anode corro- 
sion efficiency of less than 95 per cent will ruin the solution 
regardless of any treatment. 

The action of the small percentage of chromous chloride is not 
so readily explained nor is it as conspicuous. The chromium 
appears to be plated out slowly. Analysis of a typical deposit 
showed 0.3 per cent chromium, which is probably in the metallic 
condition, since the amount of inclusions of electrolyte in the 
deposit were far too small to account for such a quantity of 
chromium. It was first considered that the chromium served as a 
carrier of oxygen and hydrogen in the same way as the hydro- 
quinone. However the evidence in support of this view is not 
strong, since oxidation of the chromium seems to proceed through 
an intermediate step when the chromium precipitates. 

It is more probable that the chromium plates out slowly to give 
a slight breaking up of the iron crystal structure somewhat after 
the idea of interleaved nickel in copper deposits.^ This point should 
be checked up, for if it proves to be correct it is possible that 
the addition of other metal salts, perhaps nickel chloride, cobalt 
chloride, or some similar salt might yield a deposit which would 
have finer crystal structure and better strength than the iron 
deposits so far obtained. 

Control of the acidity of the plating solution is not of the 
critical importance that is required in the control of the reduction 
of the bath. The solution should be slightly acid, sufficiently so to 
prevent the precipitation of ferrous hydroxide or ferrous carbon- 
ate. The minimum satisfactory acidity is probably about 0.01 per 
cent and it may go to about 0.5 per cent of HCl. The acidity of 
the bath is satisfactory when the bath is made up from good 

6 Trans. Am. Electrochem. Soc. 40, 307, (1921). 



NOTES ON THE ELECTRODEPOSITION OF IRON. 1 25 

grades of ferrous chloride and calcium chloride, and it will stand 
the addition of about 2 g./L. of concentrated HCl without produc- 
ing a deposit which is excessively brittle. The addition of ferrous 
carbonate, calcium carbonate or caustic is permissible to reduce 
the acidit}-- of the bath, but if continued to the point where iron 
precipitates as a carbonate or hydroxide, the bath immediately 
gives treeing deposits. 

Another method of keeping the bath reduced to the ferrous 
condition was under trial, but without conclusive results. Early 
experiments showed that the presence of sulfur dioxide in the 
plating bath was not harmful. It did not seem possible to add the 
gas directly, since the oxidation product, being sulfate, would 
precipitate a portion of the calcium from the bath and liberate an 
excess of hydrochloric acid. It does seem possible, however, to 
add to the bath small quantities of normal calcium sulfite made by 
suspending calcium hydroxide in water and passing in the 
weighed quantity of sulfur dioxide gas. This would yield a 
precipitate of calcium sulfate, which is harmless, and would not 
change either the calcium content or the acidity of the plating 
bath. Results at this time have not been continued far enough to 
show whether this is practical or not. 

The foregoing experiments are somewhat desultory in character 
and do not follow, as rigorously as might be desired, a definite 
line of logical research. It is hoped, however, that other workers 
interested in similar work will find suggestions of value in this 
paper. 



A paper presented at the Forty-second 
General Meeting of the American Elec- 
trochemical Society, held in Montreal, 
and brought up for discussion at the 
Forty-third meeting in New York City, 
May 4, 1923, President Schluederberg 
in the Chair. 



HEAT INSULATING MATERIALS FOR ELECTRICALLY HEATED 
APPARATUS'. 

By J. C. Woodson-. 
IXTRODL'CTION, 

Heat and heat processes enter into practically every form of 
manufacture and the industry is indeed scarce that does not 
somewhere in its organization, utilize this form of energy to 
fashion or perfect its product. This has been true of indus- 
try since its inception, yet only within the last two decades has 
there been any real effort to conserve or reduce the heat lost in 
these processes. Even today, there is very limited data available 
on the subject of heat insulating material, except for certain 
specific temperatures and under conditions which do not neces- 
sarily hold for other conditions. 

While the attempt will be made in this paper to be as general 
as possible on this subject, attention is called to the fact that most 
of the data and curves given refer to heat insulating material used 
in connection with electrically heated apparatus. It is vital and 
absolutely necessary to conserve all the heat possible with such 
apparatus, which also requires careful attention to other char- 
acteristics of insulating material ordinarily considered unimpor- 
tant. The rapid and almost phenomenal increase in the commer- 
cial use of electrically heated apparatus, ovens, furnaces and 
machines, indicates that all other forms of heat and heat treat- 
ment will sooner or later be supplanted, to a large extent, by elec- 
tric heat. This change is now and will continue to be, dependent, 
to a greater or less degree, upon the available heat insulating 
mediums and the ability of engineers and manufacturers to apply 
them properly. 

* Original manuscript received August 8, 1922. 

'Electric Heating Engineering Dept., Westinghouse Elec. and Mfg. Co., E. 
Pittsburgh, Pa. 

127 



128 



J. C. WOODSON. 



TEMPERATURE RANGES CONSIDERED. 

Low temperatures, such as 80° F. (27°C.) or lower will be con- 
sidered only briefly, and for convenience we will divide our tem- 
perature ranges into the 5 divisions shown in Table I. 

Table I. 



Division 


Range 


'Application 


1 


0° 
— 18° 


to 
to 


200° 
93° 


F. 
C. 


Refrigeration, cooling, water heating, 
drying, presses, air heating, various 
liquids. 


2 


200° 
93° 


to 
to 


350° 
177° 


F. 
C. 


Steam pipes, drying, color enamel, 
presses, baking. 


3 


350° 
177° 


to 
to 


600° 
315° 


F. 
C. 


Japanning, core baking, bread baking, 
presses, appliances, liquids. 


4 


600° 
315° 


to 
to 


1,000° 
538° 


F. 
C. 


Tempering, annealing, solder, babbitt, 
tin melting. 


5 


1,000° 
538° 


to 2.000° 
to 1,093° 


F. 
C 


Heat treating, drawing, forging, 
melting, enameling. 



To cover these five ranges, there are numerous commercial 
grades of insulating material of various trade names and ratings ; 
a great many for divisions one and two and tapering off to only 
two or three reliable grades for division five. Practically all of 
these commercial grades can be located in three classes by funda- 
mental composition as stated in Table II. 

9 

Table II. 



Class 


Division 


Composition 


A 


1 


Hair, wool, felt, wood pulp, animal 
and vegetable fiber, asbestos paper, 
cork. 


B 


2, 3, 4 


Asbestos, magnesia, sponge, earths, 
mineral wool. 


C 


4, 5 


Diatomaceous earth, mineral wool, 
earths, silicates. 



From this Table, it is evident that there is no clear or definite 
dividing line between either the temperature division or the classes 



HEAT INSULATING MATERIALS. 1 29 

by composition, as there is a certain amount of overlapping. Cer- 
tain combinations of these fundamental ingredients also produce 
distinct grades of insulation, entirely different from any of the 
component parts. Also, certain ingredients are used in one class 
as insulating material, and in another class as a mechanical binder 
or strengthener of the true insulation, such as asbestos in classes 
B and C and mineral wool in class C. 

There are numerous qualities desired in heat insulating mate- 
rials and different applications require different qualities, but in 
general a good heat insulating material should have the following 
characteristics. 

1. Low heat conductivity. 

2. Low specific heat. 

3. Low specific gravity. 

4. Non-inflammable. 

5. Strong and durable mechanically. 

Low conductivity to reduce radiation losses; low specific heat 
to save as much power in heating up period as possible and make 
apparatus faster; low specific gravity to keep down unnecessary 
weight and save heating up power as No. 2 ; non-inflammable as 
most insulations are subjected to periodic or locally high tempera- 
tures ; No. 5 for length of life and reliability. 

Other attributes to be desired are : 

6. Electrical non-conduction. 

7. Have no chemical action on metals. 

8. Easily shaped or formed. 

9. Permanent in setting (no shifting or settling). 

10. Impervious to action of liquids, (water, acids, oil)^. 

Practically all commercial insulations have most of these quali- 
ties in some degree, the two last being the ones most often left out. 
In the writer's experience. No. 10 is not attained by any present 
day insulations ; though several grades will stand drenching in 
water and after being thoroughly dried prove to be practically 
as good as ever. However, while still wet, this insulation is almost 
useless^. 

'Weidlein, Chem. and Met. Eng., 24, 295, (1921). 



I30 J. C. WOODSON. 

An evacuated space is the best thermal insulator of conducted 
heat known, while gases under certain conditions are probably 
next. Air is a good insulator if it can be entrapped in small 
enough spaces to prevent convection currents, and to this fact and 
arrangement most present day heat insulators owe their value as 
such. This minute honey-combing of the structure places multi- 
tudes of confined dead air spaces in series opposing the heat flow, 
with only minute point contact of the material fibers or crystals 
for direct conduction. 

Heat transfer by radiation through insulating material is prob- 
lematical, as these radiations are stopped by the insulation and the 
heat carried by conduction ; or with some insulations the rays are 
to a certain extent refracted so that the penetration is relatively 
shallow. At temperatures beginning with 300° C. this character- 
istic is important. 

The law of heat flow through resisting materials is analogous 
to Ohm's law for electrical circuits, expressed as I = E/R where 
I is the current, R the resistance and E the voltage pressure or 
difference between two points. Likewise the amount of heat flow- 
ing between two points of dififerent temperatures can be expressed 
as 

w = f a) 

where W is watts flowing as heat, Td is temperature difference 
and R is the thermal resistance of the path of flow. This means 
that the rate of heat flow is directly proportional to the tempera- 
ture pressure or dift'erence, and inversely proportional to the 
resistance of the path or material composing the thermal circuit. 
From the above, it follows that 

R = ^ (2) 

w 

In formulas 1 and 2, Td is expressed in °C. R is the total thermal 
resistance of the circuit. Therefore 

R=:kr=^.± (3) 

A A c 



HEAT INSULATING MATERIALS. 13I 

Where 
R := total resistance of circuit in thermal ohms 
h = length of circuit in inches 
A = area of path in sq. in. 
r =: specific resistance of circuit in thermal ohms per inch 

cube 
c = thermal conductivity in watts per inch cube per °C. 
(r = 1/c) 

By substituting in formula No. 1, we have 

= — . = — . c . TdC) (4) 

L r L 

Where W is watts flowing per unit of time. Tables III, IV, and 
V, give the values of r for a number of building and insulating 
materials. 

The above simple formulae are little recognized and seldom 
used, due to the many awkward and arbitrary units ordinarily used 
by engineers, so that while the rule remains simple, the means of 
applying and using it are often complicated and involved. In this 
country, the usual unit used is the British thermal unit, and the 
method of expressing heat flow is given by the equation 

Q = KAt (^^^1^^) (5) 

Where Q is the quantity of heat flowing through a path of area 
A in time "t" the length of the path is "th" with a temperature 
difference of T^ — T.. K is the coefficient of thermal conduc- 
tivity of the material of the circuit. These units are ordinarily 
expressed as follows. 

Q = B. t. u. transmitted 

A = sq. ft. 

t =: hours 

th = inches 

T, — T, =r °F. 

K = B. t. u. per sq. ft., per inch of thickness, per hr., per °F. 
temperature difference 

* C. p. Randolph, Trans. Am. Electrochem. Soc. 21, 543. (1912). 



132 



J. C. WOODSON. 



Table III. 



Material 



Air 

Air-cel asbestos 

Balsa wood 

Cabot quilt 

Calorox 

Cork board 

Cotton wool 

CjT)ress wood 

Eiderdown 

Eiderdown 

Fibrofelt 

Gimco thermalite . . . 

Ground cork 

Hair felt 

Hard maple (wood). 

Insulite 

Kapok 

Keystone hair felt . . . 

Linof elt 

Lith board 

Mahogany wood . . . . 

Nonpareil corkboard. 

Oak wood 

Pulp board 

Remanit (charred silk) 

Sheep's wool 

Tar-paper roofing . . . 

Vacuum 

Virginia pine 

White pine 

Wool felt 



Density 
lb. per 
cu. ft. 



0.08 
8.8 

7.5 
16.0 

4.0 

6.9 

7.0 
29.0 

6.77 

0.134 
11.3 
17.0 

9.4 
17.0 
44.0 
11.9 

0.88 
19.0 
11.3 
12.5 
10.2 

34.0 
38.0 



6.9 

55.0 

34.0 
32.0 
21.0 



I K 

Spec. E- t- "• 

Heat P^^, 

sq. ft. 

! etc. 



0.240 
0.281 



0.44 
0.362 



0.20 

0.48 
0.40 



0.40 

0.32 
0.50 



0.57 



0.67 
0.39 



0.175 

0.500 

0.350 

0.321 

0.221 

0.279 

0.291 

0.666 

0.1345 

0.438 

0.329 

0.272 

0.296 
0.246 
1.124 
0.296 
0.237 
0.271 
0.300 
0.379 
0.304 

0.916 
1.000 
0.458 
0.274 
0.246 
0.708 
0.041 
0.958 
0.792 
0.363 



r. 

thermal 

ohms 

per 

cu. in. 



1560.0 
546.0 
780.0 
851.0 

1235.0 
979.0 
938.0 
410.0 

2030.0 
623.0 
830.0 

1013.0 

923.0 

1110.0 

242.3 

923.0 

1151.0 

1008.0 

910.0 

721.0 

898.0 

298.0 
273.0 
596.0 
996.0 

1110.0 
386.0 

6666.0 
285.0 
345.0 
752.5 



At 

temp. 

"F. 



n 

77 
77 
77 
77 
77 
77 
77 
212 
212 
77 
93 

77 
77 
77 
77 
77 
77 
77 
77 
150 

77 
77 
77 
300 
300 
300 
300 
300 
300 
300 



Authority 



Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Randolph 
Randolph 
Van Dusen 
General Ins. and 

Mfg. Co. 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Armstrong Cork and 

Insulation Co. 
Van Dusen 
Van Dusen 
Van Dusen 
Stott 

Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 
Van Dusen 





HEAT 


INSULATING MATERIALS 




133 






Table IV. 










Density 


Spec. 
Heat 


K 

B. t. u. 


r. 

thermal 


At 




Material 


lb. per 
cu. ft. 


per 

sq. ft. 


ohms 
per 


temp. 


Authority 








etc. 


cu. in. 






Air-cel asbestos 


8.8 


0.292 


0.500 


546.0 


17 


Van Dusen 


Air-cel asbestos 


15.6 




0.683 


399.0 


to 392 


Randolph 


Asbestos felt 


30 to 40 




0.549 


497.0 


400 


Franklin Mfg. Co. 


Asbestos fiber 


12.5 to 18.7 




0.608 to 


448.0 to 












0.497 


548.0 


932 


Randolph 


Asbestos fire felt . . . 


27.6 




1.093 


249.0 


370 


McMillan 


Asbestos lumber 


123.0 




2.710 


100.5 




Van Dusen 


Asbestos mill board.. 


61.0 




0.833 


328.0 




Van Dusen 


Asbestos paper 


50 to 70 


0.300 


1.250 


218.5 


150 


Marks 


Asbestos sponge felted 






0.509 


537.0 


400 


Stott 


Asbestos sponge felted 


34.4 




0.329 


830.0 


392 


Randolph 


Carey carocel 






0.540 


506.0 


370 


McMillan 


Carey duplex 






0.636 


429.0 


370 


McMillan 


Carey 85% magnesia. 


18.0 




0.546 


500.0 


370 


McMillan 


Carey 85% magnesia. 


18 to 24 


0.312 


0.500 


546.0 


300 


Wiedlien 


Carey 85% magnesia. 


18 to 24 


0.312 


0.585 


467.0 


600 


Wiedlien 


Carey serrated 






0.682 


401.0 


370 


McMillan 


Celite powder 


10.6 


0.289 


0.309 


883.0 


n 


Van Dusen 


Diatomaceous earth 














and asbestos 


20.7 




0.497 


549.0 


to 750 


Randolph 


85% magnesia 


13.5 




0.455 


600.0 


to 7.50 


Randolph 


Fire felt roll 


43.0 




0.624 


438.0 


n 


Van Dusen 


Fire felt sheets 


26.0 




0.583 


468.0 


77 


Van Dusen 


Fullers earth 


33.0 




0.708 


386.0 


77 


Van Dusen 


Gypsum plaster 


56.0 


0.26 


2.250 


121.4 


77 


Van Dusen 


Insulex 


29.0 


0.281 


0.916 
0.549 


298.0 
497.0 


77 

400 


Van Dusen 


J. M. asbestocel 


McMillan 


J. M. asbestos sponge 


12.0 












felted 


42.0 
13 to 16 


0.312 


0.468 
0.507 


583.0 
538.0 


370 
370 


McMillan 


J. M. 85% magnesia.. 


McMillan 


J. M. 85% magnesia.. 


16.8 




0.444 


615.0 


470 


J. M. Co. 


J. M. fine corrugated 














asbestos 


15.6 




0.538 
0.666 


507.0 
409.0 


470 
370 


J. M. Co. 


J. M. indented 


McMillan 


J. M. moulded asbes- 














tos 


21.6 




0.778 
1.087 


351.0 
251.0 


370 
370 


McMillan 


J. M. vitrobestos .... 


McMillan 


K. & M. air-cel asbes- 














tos 


12.5 


0.48 


0.680 
0.433 


402.0 
631.0 


370 

400 


Stott 


Laminated cork 


Stott 


Mineral wool 


12.5 


0.198 


0.275 


993.0 


77 


Van Dusen 


Mineral wool 


26.6 


0.198 


0.479 


570.0 


932 


Randolph 


Nonpareil H. P 


22.56 


0.20 


0.470 


581.0 


370 


McMillan 


Nonpareil H. P. block 


27.0 


0.20 


0.543 


502.5 


370 


McMillan 


Plastic 85% magnesia 






0.587 


465.0 


370 


McMillan 


Poplox 


1.43 
5.80 




0.384 
0.463 
0.350 
0.510 


712.0 
589.0 
780.0 
536.0 


572 

932 

77 

370 


Randolph 


Poplox 


Randolph 


Rock cork 


Van Dusen 


Sallmo wool felt 


McMillan 


Silica 


106.0 
10.0 


0.45 
0.20 


1.775 
0.418 
0.320 


153.8 
653.0 
853.0 


932 
400 
200 


Randolph 


Solid cork 


Stott 


Thermo fiber' 


F. D. Farnum and Co 


35% magnesia 


29.8 




0.569 


480.0 


to 750 


Randolph 


Vitrified Monarch 














block 


40 to 45 




0.842 


324.0 


400 


Franklin Mfg. Co. 



134 



J. C. WOODSON. 



Table V. 



Material 



Density- 
lb. per 
cu. ft. 



Alundum brick 127 to 149 



Bauxite brick . 
Carborundum . 
Chromite brick 



Concrete , 

Feldspar 

Fire brick ! Ill to 178 

Gas retort brick ', 



118.0 
128.0 
128.0 

170 to 180 



Spec. 
Heat 



Glass 

Glass 

Graphite brick 

Infusorial earth 

Insulbrix 

Iron 

Lime stone 

Magnesia brick 

Nonpareil brick 

Nonpareil brick 

Retort brick 

Sand 

Silica brick 

Silo-cel brick 

Silo-cel brick 

Silo-cel powder 

White buildings brick. 



150 to 170 

112.0 

43.0 

36.0 
480.0 
170.0 

125.0 

27.0 

25.8 
116.0 
110.0 

98.5 

30.0 

31.0 

12 to 15 

118.0 



0.174 

0.20 

0.253 

0.18 



0.19 

0.118 

0.217 

0.324 

0.20 

0.295 

0.195 

0.29 

0.225 

0.2089 

0.2089 



K 
B. t. u, 

per 
sq. ft. 

etc. 



7.26 to 
4.03 
9.41 

40.8 

7.19 to 

19.5 
6.38 

16.05 

10.1 to 

12.4 

11.03 
7.00 
4.33 

71.9 
0.583 
0.84 
420.0 

15.0 

17.05 
1.10 
0.477 

10.95 
2.70 
5.81 
0.67 
0.745 
0.300 

10.90 



r. 

thermal 

ohms 

per 

cu. in. 



37.5 to 

67.7 

29.0 
6.69 
38.0 to 

14.0 

42.8 

17.0 
27.0 to 

22.0 

24.7 

39.0 

63.0 

3.8 

468.0 

325.0 

0.65 

18.2 

16.0 
248.0 
572.0 

24.9 

101.0 

47.0 
407.0 
366.0 
910.0 

25.0 



At 




temp. 


Authority 


1112 


Randolph 


1832 


Randolph 


2072 


Randolph 


2072 


Randolph 




McMillan 


212 


Randolph 


2072 


Randolph 




Marks 




McMillan 


78 


Randolph 




Randolph 


77 


Van Dusen 


1000 


Quigley Fur. Spec. Co. 




Marks 




McMillan 


2072 


Randolph 


1600 


Armstrong Cork Co. 


470 


McMillan 


2072 


Randolph 




McMillan 


1832 


Randolph 


470 


McMillan 


1600 


Celite Prod. Co. 


77 


Celite Prod. Co. 


1832 


Randolph 



Many of the materials given in the Tables III, IV and V are not heat- 
insulating materials in the ordinary sense of the term, but are given only 
for purposes of comparison. The authorities given refer to the value 
of K. K is expressed as B. t. u. per hour, per square foot, per inch of 
thickness, per ° F. difference. 



HEAT INSULATING MATERIALS. 1 35 

For flat surfaces of sufficient area so that the end or edge effect 
is relatively small, this formula can be used as given, though only 
approximately correct. AIcAIillan gives this formula as 

Q = *^~*t (6) 

^ X 1 ^ ^ 

k a 

Where 
Q = B. t. u. per sq. ft., per hr. transmitted 
ts = temperature of hot surface, °F. 
ta =: temperature of surrounding air °F. 
X z= thickness of insulation in inches 

a =: surface transmission factor (1/a =^ surface resistance) 
k = conductivity of material. 

This takes into account, not only the absolute mean conductivity 
of the insulation, but also the resistance that is offered by the 
surface of the material to the transmission of heat. This factor 
1/a varies between wide limits, and has been determined for only 
a few materials, so that for ordinary calculations 0.5 is taken as 
the value of 1/a for still air conditions and a good grade of insulat- 
ing material at medium temperatures. 

f f 

From formula No. 5 it is evident that the factor —^ ^ is the 

th 

determining variable, and expresses the rate of temperature drop 
with distance through the material, and its limiting value or 
dT/dth is the "temperature gradient" of any point in the path of 
flow, assuming that K is a true constant for the full thickness of 
the materials. 

For cylindrical surfaces such as steam pipes, tanks, boilers, etc.,. 
it can be shown that the heat loss is equal to 

Where 

Rj is inside radius of covering in inches 

R, is radius of outside of covering (or insulation) in inches 



136 



J. C* WOODSON. 



R is outside radius of pipe in inches (usually taken equal to 

Ri in above equation) 
Q is rate of heat flow per in. B. t. u. per sq. ft., per hr. 
Tj is temperature of inside of pipe in °F. 
T, is temperature of outside of insulation °F. 

This is the formula generally used for all cylindrical surfaces 
and Table IV gives the value of K for a number of different 






,' 



/ 



X 



/ 



Tfrsrma/ CorK^ucityify 



A/o' 7 pare I 



' Mfh 



^res^u rs ff/oi. vf 



zoo 300 4CC soo bco 700 aoo 
Te/rrperature Difference -Ue^rees^ 

Fig. 1. 



insulations commonly used for such surfaces. T, is ordinarily 
taken as the temperature on the outside surface of the covering 
or even room temperature, whereas it actually refers to the tem- 
perature of the outside of the insulation, which for steam pipes 
would be under the canvas sheathing. 

In the above formulae, numbers 4, 5, 7, etc., two assumptions 
are made which are not strictly correct ; first, that K is constant in 



HEAT INSULATING MATERIALS. 



137 



value throughout the thickness of the insulation, and second, that 
the value of K varies inversely with the thickness. The value of 
K varies with the temperature as shown in Fig. 1, so that it pre- 
sents a curve between T^ and T,. It is a matter of common knowl- 





























































































































— \\ 




Terrrp . 


7,ff Si 
3C 
10 


o'r 




















Ir 






V 


\ 






















\ 


\ 




















04 




\^ 
























\ 


\\\ 
























^ 


\\ 
































:^===~ 































T/7/C Alness - //7c//es-8S VoAfefy^es/a- 
yanaf/on 0/ /7eo/ ^rtf/7Srr7isscon for \^artO(/s 
t/7icf^nesses of mo^erio^ orr fiai surfaces 
Fig. 2. 



edge that the insulating value does not increase directly with the 
thickness, but so far no general law has been worked out. Stott'' 
attempted this and states that for 85 per cent, magnesia, the law is 



K2 



V th, 



(8) 



» Power, 1902. 
10 



138 



J. C. WOODSON. 



Where K^ and K^ are the coefficients of conductivity and th^ and 
tho are the thicknesses, while for every other material a different 
constant is required. These have not been accurately determined 
as yet. Fig. 2 shows this general relation for 85 per cent magnesia 
on flat surfaces. Stott's law will not hold for fiat surfaces as it 



T/?iC/Cr>ess of /ls/>es/os fo/yer ts C^S t/7c/> 



??(i 






















?.in 




\ 




















?no 






\ 


















f^n 






\ 


^ 
















fflO 






^ 


\ 
















r-7r 


He, 


■.-/ ceo 




^ 


1 














l.i.C 










\ 


\ 












1 so 












\ 












140 












< 


\ 










f=tn 














^ 


\ 


























■v 






1?0 


■ \ 

K 


^cr br, 


r^t rc 


tin 








N 


- 





























1 2 3 4 .5 <i> 7 8 

/Vi/mber of tfricKnesses cT /ishestos /''o/>er 

Curk'e s/iCkV{f70 if7e/^/'ec/tt'enes3 c/" (Tc^rrercio/ As^s/es roper /or 
inSi/Ja/ic/7 o/" Brif/ti Tin Piptr 

Fig. 3. 



takes into account the increased radiating surface on a pipe or 
cylinder. 

From the above, it will be seen that these two conditions tend 
to counteract each other, so that the result is a curve that will 
vary for each temperature and each insulating material. Common 
practice is to follow the inverse square root law for cylinders, and 



HEAT INSULATING MATERIALS. I39 

use a multiplier for flat surfaces, such as ovens, which really 
depend more upon the mechanical construction of the oven than 
upon the characteristics of the insulation. This multiplier for 
formula No. 5 varies from 1.2 to 2.5, depending on conditions. 

For many applications, such as medium temperature ovens and 
high temperature furnaces, it is customary to construct the v^ralls 
of layers of different materials having different internal resist- 
ances. The heat loss from such a flat wall can be calculated by 
the following formula ; using the notation and form of formula 
No. 5 we have 

ki kj kn 

where th is the thickness of the various layers and K the conduc- 
tivity ; or more accurately this is given by McMillan as 

Q = t^^ta ^^^^ 

using the same notations as formula No. 6. For cylindrical sur- 
faces this becomes 

Q = — T , '"^f^^i r (11) 

fs loge tg/ri ts lege tJt^ 4- -^ 

ki kj a. 

in which is is radius of outside surface of insulation r^ is outside 
radius of cylinder and r, equals r^ plus thickness of first layer of 
insulation, t^ equals rj plus thickness of second layer, etc. 

APPUCATION TO APPARATUS. 

The materials in class A Table II are used successfully only for 
quite low temperature work, and due to this fact the heat loss is 
generally low regardless of insulation used. For this reason, little 
attention is paid to the proper selection and too often a few layers 
of asbestos paper is used, as this is easy to obtain almost anywhere. 
It has been shown that the heat loss from a bare bright tin pipe 
is less than from the same pipe covered with 7 layers of 0.025- 



140 



J. C. WOODSON, 



"inch (0.64 mm.) asbestos paper at approximately 180° F. (82°C.) 
in the pipe (Fig. 3)®. So it is obvious that it would be better 
economy to use some of the fibrous or spongy insulations given 
in Table III even though the first cost and cost of installation was 
higher than for the asbestos paper. 

Class B, Table II, is by far the most important class, as most 
commercial and industrial applications fall within it. To meet this 




Fig. 4. 



demand there are dozens of grades and brands of commercial insu- 
lations on the market. Table IV gives only a few representative 
grades of this class. Much care should be exercised in the selec- 
tion of an insulation in this class, as many are good under certain 
conditions and poor under other conditions at the same tempera- 
tures. For instance some will stand soaking in water and when 
dried out are apparently as good as ever. Others disintegrate and 
fall to pieces under the action of water or any other liquid. Some 
grades will stand up and hold their place and position under con- 

« University of 111. Bulletin No. 117. 



HEAT INSULATING MATERIALS. 



141 



tinual jarring and vibration, others settle down and leak out of 
their retaining walls and leave an air space. So other considera- 
tions besides thermal characteristics are important, depending 
upon the particular application^. 

In the application of these insulations to electrical apparatus, 
the largest per cent will go on tanks, boilers, etc., and on ovens. 




Fig. 5. 



drying cabinets, etc. These are shown in figures 4 and 5. On the 
former the insulation is usually applied exactly as pipe covering, 
with an outer surface of canvas, while with ovens the insulation 
is ordinarily confined between two thin sheet metal walls. In 
building such ovens, care should be exercised so to construct 
them that there is a minimum of continuous through metal from 
inside to outside of the wall ; that all joints are tight and well 

TE. R. Weidlein, Chem. and Met. Eng. 24, 295, (1921). 



142 



T. C. WOODSON. 



























^ 
















Q^ 


/ 


/ 


















/ 


k 


^ 






^ 












/ 


/ 










> 


^ 








} 


/ 

/ 












^ 


1 






/ 


/ 

o 0/ 


/ 












s 




/ 


V 


Y 


Ten 


7prro^ 


yrp - // 


7/?^/ C 


jrt^e 




^ 


t?: 


/ 


'/ 


/ 

> 




•A/o. 
A'o.. 






•Vool // 


r Inst/ 1 








// 


/ 


















^ 


/ 


/ 






















/ 








^ocm 


Tamp. 






















' 0- 






















/npu 


' t'n Wc 


rts 


1 







tA/c/r 



JSOO 

Fig. 6. 



^ 
































^ 
































8 


^ 










^^ 


^ 

















— 


? 


^ 

^ 






^ 


^ 


^^ 




3- 




Tt/r> 


fre.^^ 


ers'ui 


fCur^ 


? 






1 






y 












.\c.-2 '^'-> 










^ 


/ 


X 












.\c2- 

Curn 








1>7 


R 


/ 


V 


























1 










































r,^ 


t m /^ 


'>^u*»t 

















Fic. 7. 



HEAT INSULATING MATERIALS. 



143 



packed ; and that the outer surface of the oven is one that does not 
radiate the conducted heat readily. Cases are on record of similar 
ovens in which one was finished in black iron and one in bright 
galvanized iron. At 500°F. (260°C.) the black oven showed a 
radiation loss 30 per cent greater than the galvanized oven. Other 
conditions may have contributed to this difference, but it is believed 




2O0 3te 400 xu 

Heai los^s from Bars /ro/7 F'tpe efsc^eferminetJ S^ i/ar40t/3 fnifa.^ii gators 
The figures Yz" , H", etc., indicate the diameter of the pipes. 
Pig. 8. 

the different character of surface was the main cause. In ovens of 
several hundred square feet radiating surface, this is a feature to 
be watched closely. 

As brought out previously, it is essential that the specific heat 
or heat absorbing power of an insulation be taken into considera- 
tions as well as its conductivity. Fig. 6 and 7 show curves of 
identical ovens, one with a commercial grade of mineral wool, the 



144 



J, C. WOODSON. 



Other with a commercial grade of aircel asbestos insulation. It will 
be noted that the former not only has a lower constant loss, but 
comes up to temperature more rapidly, thus storing less power to 
be lost when the oven is shut down at night. 

Some of the insulating materials in Table V can be, and' often 
are, used for temperatures as low as 300° F. (149°C.) but their 
real field lies in furnace work, where temperatures of 1,000 to 
3,000° F. (538 to 1,650°C.) are encountered. 




Fjg. 9. 



While these insulators will stand direct contact with the heating 
elements and temperatures of 2,000° F., it is better practice to line 
the inside of the furnace with a good grade of refractory fire brick, 
and place the insulating brick outside of these. As these insulating 
brick are not strong mechanically, a layer of building brick or red 
brick outside of them will protect them and insure permanent 
insulating value. Fig. 9 shows one of the large electrical furnaces 
insulated in this manner. 

Due to the fact that the absolute mean conductivity of air is 



HEAT INSULATING MATERIALS. I45 

considerably lower than any present day commercial insulation, 
industrial plant engineers often try to increase the efficiency of 
furnaces and boiler settings by including air spaces in the walls. 
The results are invariably the opposite from those desired. This is 
due to the fact that even thin air spaces readily set up convection 
currents, and that the radiant heat leaps across the air space with 
little opposition, especially if the air space is close to the inside 
of the furnace. 

Tests by the U. S. Bureau of Mines, proved that a wall of solid 
fire brick or building brick lost less heat than a similar wall with a 
2-inch (51 mm.) air space enclosed in it^. Therefore this practice 
is poor and should be abandoned entirely where medium and high 
temperatures are involved. 

CONCLUSIONS. 

k 

While there are numerous grades of heat insulations on the 
market, there are none that can compare with electrical insulators. 
Of all the different grades, there are only a few fundamentally 
different sorts, as some half dozen items will cover the raw mate- 
rials successfully used. In all these materials the true insulation 
value lies almost entirely in the entrapped dead air spaces of their 
structure. The difference between grades then really goes back 
to the physical structure of the crystals or cells. This fact leads 
many engineers astray in the use, in furnace and oven walls, of air 
spaces, which actually increase rather than decrease the heat loss. 

The application of poor insulation can have the same effect as 
the air spaces mentioned above, as shown by the University of 
Illinois in tests of asbestos paper on hot air pipes. See Fig. 2. 

While the conductivity of an insulation is of primary importance, 
other thermal characteristics must be considered, such as specific 
heat and specific weight. The application also has to be considered 
with regard to the physical properties of the material. 

The laws of heat flow are simple and follow closely those for 
electrical energy, but are little used or understood. This probably 
is due in part to the fact that there are few reliable data available 
on the subject, and of these the values given by different authors 
vary over wide limits. 

' Bureau of Mines Bulletin No. 8. 
11 



146 DISCUSSION. 

It is the writer's opinion that a great deal more research and 
development work should be done along the lines of heat insula- 
tion engineering, as we have about come to a stop and have 
accepted our present standards by saying "there is bound to be 
a certain amount of heat lost, and this is as good as we can do." 

I believe that if there was a wider distribution of available data 
and a broader dissemination of the laws and character of heat 
flow and its prevention, it would help to conserve the national 
coal supply and result in better insulation methods being developed. 
The progress of electrically heated apparatus is dependent to a 
large extent upon the efficiency of its insulation, and warrants the 
keenest attention of electrical, chemical and mechanical engineers, 
as well as of heating and ventilating engineers. 



DISCUSSION. 



Carl Hering^ : Mr. Woodson spoke of the thermal ohm. 
This is decidedly the best unit to use for electrical engineers, who 
deal with energy in electrical units but it is not the most conve- 
nient unit to use when you are dealing with B. t. u.'s and calories, 
as in the case of steam pipes. It is something Hke using the cir- 
cular mil and the square mil ; each of them is the best unit to use 
under particular circumstances, because the conversion factor is 
then unity. 

I do not know whether Mr. Woodson called attention to 
another point, namely the effect of joints in the insulation, which 
is quite important. For instance, if in the wall of a furnace the 
bricks are placed on edge, you get a much better insulation than 
if placed flat, because there is an extra joint, and a joint is a very 
important heat insulator. I have seen the material on one side 
of a joint red hot, while on the other side it was black. There is 
great heat insulation in a joint. 

He refers to the spaces in finely divided material. The late Mr. 
Stanley ,2 of the General Electric Company, made researches with 
such material several years ago, and found the interesting results 

'Consulting Electrical Engr., Philadelphia, Pa. 
^ Personal communication. 



HEAT INSULATING MATERIALS. 147 

that as such material is compressed, which means that the air 
spaces become smaller, the heat insulation at first improves, but 
after reaching a certain point, if you compress it still more, the 
heat insulation again diminishes. There is a maximum point to 
which one should compress such granular or fluffy material. 

Foundrymen have discovered that if they whitewash the out- 
side of a furnace, it makes them feel more comfortable, which 
to us means that whitewashing the outside of a furnace adds quite 
a little to the heat insulation ; it is hotter to the touch, but emits 
less heat. 

F. A. J. FitzGerald^: Joint heat insulation referred to by 
Dr. Hering is particularly noticeable in carbon electrodes. For 
example, in an Acheson graphite electrode, while a well-made 
joint may have a very low electrical resistance, the resistance of 
the flow of heat is extremely high. In furnaces with metallic 
resistors, where the terminals are made of some metal, it would 
be interesting to find out if one could get a low electrical resistance 
with a high heat resistance. 

J. C. Woodson {Communicated) : The matter of surface or joint 
resistance to heat flow is gone into on page 135 on this paper, and 
is largely responsible for increased insulating value of insulation 
when this insulation has several distinct joints or parallel sur- 
faces. This is also a partial explanation of the increased effi- 
ciency found in insulated walls using more than one kind of 
insulating medium in the same wall. IMore definite data should 
be made available on the true value of the surface resistance of 
insulating materials under varying conditions. 

*FitzGerald Labs., Niagara Falls, N. Y. 



A paper presented at the Forty-second 
General Meeting of the American Elec- ■ 
trochemical Society held in Montreal, 
and brought up for discussion at the 
Forty-third meeting in New York City, 
May 4, 1923, President Schluederberg in 
the Chair. 



METHODS OF HANDLING MATERIALS IN THE ELECTRIC 
FURNACE AND THE BEST TYPE OF FURNACE TO USE^ 

By Frank W. Brooke* 

Abstract. 
The author discusses, in general, the design of various electric 
furnaces, such as the plain box type, the special box type, the car 
type, the recuperative and continuous furnaces, and refers to their 
advantages and disadvantages. Attention is drawn to the method 
of handling materials for these furnaces, so that a uniform tem- 
oerature and high furnace efficiency may be maintained. 
^ [A. D. S.] 



The outstanding engineering features that have made the mod- 
ern electric furnace for temperatures up to 980° C. (1800° F.) so 
successful are the drawn nickel-chromium resistance elements and 
the high standard of thermal insulation. Those who have read 
the many interesting papers presented at various times, especially 
by such authors as Mr. E. F. Collins, will realize the careful study 
and pioneer work that has been given to these subjects, and the 
accurate data that have been compiled by those interests that are 
successfully pushing the electric heat-treating furnace. 

One problem, however, that will not be standardized for many 
years to come is the method of handhng the material to be 
treated both while it is in the furnace and out of the furnace. 
The efficiency of the best design of furnace can be entirely ruined 
by poor handling methods. On the other hand, given a particular 
method of handling the material, it becomes a problem for an 
experienced furnace engineer to design the furnace to meet this 
method. 

> Original manuscript received September 20, 1922. 

» Chief Engineer, Wm. Swindell & Bros., Pittsburgh, Pa. 

149 



I50 



FRANK W. BROOKE. 



Take, for instance, the handling of very hght materials in 
many of the existing fuel-fired furnaces. Strength and resistance, 
as long as possible to scaling, has necessitated a high ratio of the 
weight of the handling medium in the furnace to the work being 
treated. It is quite common to meet cases where this ratio is 2 
to 1, or more, which means that twice as much fuel is expended 
in heating the holding or carrying device as in heating the work. 




2J> 



Fig. 1 



The electric furnace designer has met these cases in a proper 
engineering manner. The whole of his furnace engineering is 
taken from accurate mathematical data. The heat input is exact 
and constant. He studies specific heats not only at room tem- 
peratures but along the range of his working temperatures. He 
calculates the heat losses and so forth. Besides, he is not con- 
fronted with the eating away of his holding devices by oxidation 
to the same extent. 

It is the object of this paper to point out some of the advantages 
and disadvantages of various furnace designs and methods em- 



HANDLING MATERIALS IN ELECTRIC FURNACES. 



151 



ployed in the handling of materials for electric furnaces at the 
higher temperatures. 

The plain box type of furnace having, say, one door: This design 
is simple and the many methods of handling material for it are too 
well known to require description. It allows for high grade thermal 
insulation, and care need only be taken to provide against the 
door losses. This is done by making a well-sealed door, and by 
doubling up resistance elements at the door ends. See Fig. 1. 

Special box type: In electric furnaces the volume of the furnace 
chamber is not restricted to the same degree as in the fuel-fired 
furnace, and therefore lends itself to the use of special design, 
such as is shown in Fig. 2. This furnace is designed for the 
accurate heat treatment of steel products having varied lengths, 
where the output does not warrant the use of a different length 
of 'furnace for each different length of product. 




Fig. 2 



It is fitted with three partition doors, each having a special 
seal, and the heating units are so placed that there is a uniform 
heat distribution under all conditions of operation. The end 
doors face into two different shops and give an extremely flexible 
arrangement for the class of work for which it was designed, at a 
firgt cost and an operating cost both much lower than if separate 
furnaces were used. 

Another interesting variation of box type furnace is one in 
which a preheating chamber is put back to back with the high tem- 
perature chamber, having in this case only one partition wall. This 
is used for vitreous enameling work, or for heat treating fine tools. 
In the latter case the low temperature chamber can also be used 
for drawing. 



152 



FRANK W. BROOKE. 



For vitreous enameling a special form of hearth is used, either 
for facilitating the handling of the work, as in thin sheet work, 
or for allowing a large amount of the heat to be applied at the 
bottom of the work to be treated. It is essential, as in bath tub 
work, for the enameling to be done "through the work" as well as 
from the upper surface. 

Car type: This gives a much better handling arrangement,, 
especially for large pieces handled by the crane. In considering its 
use, it should be borne in mind that when the car is withdrawn 
from the furnace the entire hearth bottom is exposed to rapid heat 
loss. In order to give high thermal efficiency and uniformity of 
temperature, an electric furnace car bottom is much more massive 
than that used in the ordinary fuel-fired furnace, and when; 
exposed to direct radiation loss it loses a greater quantity of heat. 




Fig. 3. 

For this reason the time cycle of electric car type furnaces 
should be arranged to ensure the car being rapidly unloaded and 
reloaded, or else a dummy furnace should be provided, as shown 
in Fig. 3, whereby there is an exchange of heat not only between 
the cooling of a hot charge to a cold charge but also from car to 
car. For heat treatments requiring a long time of heating, hold- 
ing and cooling in the furnace, it is advantageous to build the door 
directly on to the car. 

Recuperative furnaces: Fig. 3, already referred to, is perhaps 
the simplest form of this type of furnace. Providing the time 
between heats is not too long and the output warrants two fur- 
naces, its use invariably pays. Where the heats are of long dura- 
tion, the steady radiation loss of the dummy furnace defeats its 
economy. 

A better form of recuperative furnace is shown in Fig. 4. This 



HANDLING MATERIALS IN ELECTRIC FURNACES. 



153 



arrangement allows for recuperation from one heating chamber, 
but on the other hand requires three chambers per unit. It 
requires also considerable rail switching, but has given excellent 
fuel economy. 

Still another form of recuperation is shown in the counter-flow 
type of furnace, the various designs of which are too numerous 
to illustrate. Fig. 5 shows a car type of counter-flow furnace, now 
used in the annealing of gray iron castings. 

The furnace is divided into seven sections, each corresponding 
to a car length. Only the middle section is equipped with heating 
units and has a short dividing wall. The heating units are sus- 




FiG. s. 

pended on the four walls so that each preheated car is heated from 
both sides. On either side of the heating section are two cooling 
and two preheating sections. 

The trains of parallel cars move in opposite directions, and each 
moves one car length at equal intervals of time. Therefore a 
heated car and its charge leaving a heating section is placed 
directly beside a car and its charge partially preheated, and is 
given a period of interchange of heat. It then moves forward 
another car length, and some of its remaining heat is given up to a 
cold car and its charge coming from the transfer chamber. There 
is also a transfer chamber at either end, enclosed in lightly insu- 
lated walls, as the cars after being reloaded still retain a consider- 
able amount of heat well worth conservinsf. 



154 



FRANK W. BROOKE. 



It is interesting to note that the first electric furnace installed 
of this design had a partition wall running the entire length of the 
furnace, in which port holes had been left at the top and bottom. 
The design of this furnace was taken from a previous fuel type 
design, but the engineers built the partition wall in such a way 
that the portions in the recuperative chambers could be readily 
removed if necessary, They soon found this to be necessary. 
It was also found that instead of longitudinal partition being 
necessary, transverse partitions between each section were abso- 



Charging y. 



end 



i+ 



^ 



Chain^ 



Drive 
shaFt 



Fig. 6. 





^/ 


^ 


'////////////////////////////////////////////, 


V//A 




Charging 
end 


1 








i 




'Gv' 


I 


k 


J yv////////////////Zvy/y//y////y////////Ai(^ ^ 


X 


^ 
^ 


'\p\ 






1 


^jjgin \. ~~' 


^ 





Fig. 7. 



lutely essential for temperature uniformity and efficient heat 
exchange. The work which is small and of very thin gray iron 
castings is placed on superimposed trays, and one end of each tray 
forms part of the transverse partition. 

Continuous furnaces: In electric furnace salesmanship it has 
been the author's experience that the prospective electric furnace 
user thinks first of all of a continuous furnace to do the work, 
feeling that a continuous furnace is a labor-saving furnace, a fuel 
saver, routes his work better and is more modern. There are, 
however, many points of electric furnace engineering to be con- 
sidered before a complete knowledge of these points can be given, 
and it is surprising how often it can be shown (excepting in such 



HANDLING MATERIALS IN ELECTRIC FURNACES, 



155 



cases as producers of large quantity of uniform products as in the 
motor car industry) that a continuous furnace is not the best all- 
round furnace to install, often proving a disappointment to the 
prospective customer. 

Fig. 6 shows a continuous furnace used for heat treating light 
flat discs, and working satisfactorily. The limiting feature of such 
a design is the temperature of the conveyor. If carried above 
650° C. (1200" F.) the stretch becomes a serious consideration. 




Fig. 8. 



A surprising feature in such a design is the loss of heat caused 
by the exposed ends of the chain. It is easy to see that the loss 
would be material, but actual experiments in one particular design 
show a thermal efficiency of about 18 per cent. This can be greatly 
improved by the proper boxing-in of the ends, but where chain 
area must be available for loading and unloading this enclosing is 
limited. 

A better arrangement for carrying light work through the fur- 
nace is shown in Fig. 7. This consists of three chain systems, only 
the middle one of which is always inside the highly insulated walls 



156 



FRANK W. BROOKE. 



of the furnace. The charging and discharging systems do not 
attain a temperature sufficiently high to cause a serious heat loss. 
When a chain system is totally enclosed in the way shown, it must 
be remembered that this chain attains the temperature of heat bal- 
ance of the furnace, which is decidedly higher than the chain shown 
in Fig. 6. It is also more difficult to take care of heat losses 
through the journals when higher shaft temperatures and stretch 
adjustment must be taken care of. 




Fig. 9. 




Fig. 10. 



The author is at the present time engaged in the designing of 
three different types of electric furnaces, in each of which the 
mechanical handling of the material is of vital importance, as the 
material must not be marked and furnace efficiency and tempera- 
ture uniformity is of utmost importance. He is not at liberty to 
publish these designs now, but hopes at some future occasion to 
give a paper on this subject. 

For the continuous conveying of work through an electric fur- 
nace at the higher temperatures, the so-called "doughnut" furnace 
offers an excellent method of carrying out the operation. A plan 
diagram of this is shown in Fig. 8. It has many advantages. The 
conveying hearth is made of refractory materials, and can there- 
fore handle materials at the limiting temperatures of electric fur- 



HANDLING MATERIALS IN ELECTRIC FURNACES. 157 

nace heat treatment. The charging and discharging doors are adja- 
cent, and in many operations one man can attend to both. The 
thermal efficiency is high, as only the hearth seals under the fur- 
nace offer any insulating difficulty. It is used to special advantage 
in the heat treatment of gears and small machine parts. When the 
work to be treated is of a uniform character, automatic loading 
chutes can be adapted, and the work can be "swept-out" at the 
discharge end. 

The "push" type of furnace is perhaps one of the most efficient 
types of continuous furnaces used, and is shown in Fig. 9. It 



Fig. 11. 

is restricted to work of a uniform shape, and work which will 
push in a long column without bridging. This tendency to bridge 
can be lessened by inclining the furnace and thus lessening the 
friction to push. It is an excellent method of conveying such parts 
as small connecting rods, push rods, small cylindrical pieces, etc., 
and fits in with production heat treatment for small parts. The 
speed of travel can be varied through a wide range and the dis- 
charge end can be sealed in the quenching tank. 

The "gravity roll" type of furnace has the same degree of effi- 
ciency and usefulness as the "push" type, but is still further 
restricted to products that will roll by gravity. The feed through 



158 



FRANK, W. BROOKE. 



the furnace can be regulated by a discharge timing gear, shown in 
its simplest form in Fig. 10. 

The "push" furnace is simple in construction, has a low 
operating cost, and has a lower first cost than the many other 
types of furnace. See Fig. 11. 

The "walking beam" type of furnace forms one of the fasci- 
nating means of handling materials through an electric furnace. It 
is restricted to uniform shapes and sizes, such as automobile 
crankshaft, connecting rods, bars of steel, etc. In the more simple 
type of walking beam, shown in Fig. 12, the beams are hned with 




Fig. 12. 



~~i nnnnnnnnnnnn,xnk\nn\\nnnnnj^nnn.nns'^.^^ 






^ 



^ 



Fig. 13. 




Fig. 14. 



refractory material, but the continuous top surfaces of the beams 
must be kept in a true horizontal plane, so that the points of con- 
tact with the work are made with each beam simultaneously ; other- 
Av-ise the work will creep more along one side of the furnace than 
the other. A good beam mechanism which ensures work tempera- 
ture uniformity and furnace efficiency adds considerably to the 
first cost of the furnace. 

An interesting variation of the "walking beam" furnace is the 
type shown in Fig. 13, designed to treat shells, crankshafts, short 
shafts, axles, etc., in such a way that the axes of the work are 
always parallel and there can be no jamming in the furnace. The 



HANDLING MATERIALS IN ELECTRIC FURNACES. 1 59 

way the work progresses through the furnace is clearly shown in 
Fig. 14. 

For the heat treatment of steel balls and similar materials, a 
design, such as is shown in Fig. 15, offers an excellent method. 
The author does not know of any furnace of this type in which 
electricity is used as a fuel, but there is no reason why electric 




Fig. is. 

resistance units cannot be applied to give all the inherent values of 
the electric furnace. 

The figures shown and types referred to are very general. It 
would be difficult to give references that would be complete and 
fair. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 4, 1923, President Schlueder- 
berg in the Chair. 



THE CONVERSION OF DIAMONDS TO GRAPHITE AT HIGH 
TEMPERATURES.' 

By M. DeKay Thompson and Per K Frouch.^ 
Microscopic Work By J. L. Gillson. 

Abstract. 

It is shown conclusively that diamonds change slowly at 1650° 
C. to a substance that gives the Brodie test for graphite, and 
that the velocity of this reaction is increased about 26 times by 
an increase of 100° above this temperature. 



INTRODUCTION, 



In looking over the previous work on this subject, there is 
found quite a lack of agreement in the results obtained by 
different investigators. This may be accounted for by inaccuracy 
in the temperature measurements, as in many cases it is not 
clearly explained how these were made, and in others it is stated 
that temperatures were only estimated. The object of the present 
investigations was to determine at what temperature diamonds 
change to some other form of carbon with appreciable velocity, 
and to determine whether or not this other form is graphite. 
It would be hopeless to attempt to verify experimentally the 
calculations of Weigert^ and of Pollitzer*, according to whom 
the temperature below which diamond is stable is respectively 
372° and 340° C, because the reaction velocity is too slow at 

* Manuscript received February 1, 1923. 

* Contribution from the Electrochemical Laboratory of the Rogers Laboratory of 
Physics, and Geological Laboratory, Massachusetts Institute of Technology, Cambridge. 

^Abegg's Handbuch der anorg. Chem. Ill, 2, p. 47 (1909). 

* Die Berechnung chemisher Affinitaten nach dem Nernstschen Warmetheorem. 
p. 136 (1912). 

i6i 



l62 M. DE KAY TH0MP50X AND PER K. FROUCH. 

such low temperatures. According to Boeke^, if the heats of 
combustion determined by Roth and Wallasch® are used in this 
calculation in place of those of Berthelot, used by Weigert and 
by Pollitzer, the result is that at atmospheric pressure diamond 
is unstable at all temperatures down to the absolute zero. 

All of these calculations were made by the Nernst heat theorem, 
the data for which are the specific heats of diamond and graphite 
down to temperatures near the absolute zero, and the total energ}'' 
change of the reaction : diamond — > graphite. 

PREVIOUS WORK. 

The references in the foot note^ are to the most important 
previous work on this subject, but in order to save space they 
will not be considered at length. They may be briefly summarized 
as follows: 

Diamond changes to graphite in the arc, but, according to 
Moissan, not at 2000° C. ; according to Doelter, diamonds are 
only blackened in the surface up to 2500° C, while Vogel and 
Tammann say diamond changes to graphite at 1200°. It was 
on account of these discordant results that the following work 
was undertaken. 

EXPERIMENTAL. 

A small Arsem^ vacuum furnace was used for heating the 
diamonds. These were placed in the center of a carbon crucible 
on a small carbon plate as shown in Fig. 1. In the first experi- 
ment the cover over the diamond was omitted. The crucible 
had a cover with a hole through which the temperature was 
taken with a Leeds and Northrup optical pyrometer, which was 
compared with a standard optical pyrometer, and the small cor- 
rection applied. The temperature had to be taken through a 
mica window in the top of the furnace. The effect of the mica 

"Centralbl. Min. Geol. und Palaontologie 321 (1914). 

«B. d.d, chem. Ges. 46, 896 (1913). 

' Moissan, Le Four Electrique, 157 (1897); Parson and Swinton. Proc. Roy. Soc. 
80, 784 (1907-8); Vogel and Tammann, Z. phvs. Chem. 69, 600 (1910); Doelter, Mona- 
thaft f. Chemie 32, 280 (19)1). 

* Trans. Am. Electrochem. Soc. 9, 153 (1906). 



C0NVER5I0X OF DIAMONDS TO GRAPHITE. I63 

window on the temperature indication was determined by read- 
ing the temperature of another furnace with the window between 
the hot body and the pyrometer, and without the window. It 
was found that at 1260° with the window in place the correction 
to be added is 40', at 1550' the correction is 60', and at 1710' 
it is 75'. Corresponding corrections were applied to the readings 
through the window. The temperature of the plate covering the 
diamond was taken. This must have been very nearly under 
black body conditions. It is believed that temperatures are cor- 
rect to within 30' C. 

The furnace was evacuated to only 5 mm. in the first four runs, 
after this two pumps were connected in series, and the vacuum 
was reduced to less than 1 mm. In any case there was little 
chance of any oxygen getting at the diamond with so much other 
carbon present, and all of the oxygen present could not have 
burnt more than a small fraction of the diamond if it burnt 
nothing else. 

The power in the furnace was kept constant by means of a 
carbon plate resistance and was read by a wattmeter. With con- 
stant power the temperature remained constant. 

The method of procedure decided on was to heat for a given 
time to different temperatures and examine the product micro- 
scopically and chemically. The chemical test consisted in the 
Brodie test for graphite, by oxidizing in a solution of nitric acid 
and potassium chlorate.^ For microscopic examination a small 
piece was cracked oft and immersed in a solution of sulfur 
in methylene iodide, which has a high index of refraction. 

The method of carrying out the Brodie test was to digest 
the sample at 60° C. with finely ground potassium chlorate and 
concentrated nitric acid for 24 hours. It was washed, dried and 
the treatment repeated. Three treatments changed a sample of 
graphite to yellow graphitic oxide. Acheson graphite was tested 
and gave a yellow product, while coke dissolved completely giv- 
ing the solution a yellow color, probably due to iron. 

The results are contained in Table I. 

' For the description of the Brodie test see Moissan, The Electric Furnace, SO 
(1904); Donath, Der Graphit, IS (1904); Selvig and Ratliff, Trans. Am. Electrochem. 
See. 37, 121 (1920). 



164 



M. DE KAY THOMPSON AND PER K. FROLICH. 



Table I. 
Effects of Heating Diamonds to High Temperature. 



No. 


Time required to reach 
highest temperature 


Duration of 

heating at highest 

temp. 


Highest 
temp. 


Vacuum 


1 




3 hr. 
2 hr. 


2060-2090 
1000-1015 


5 mm. 


2 


30 min. to 800° 


5 mm. 




1 hr. at 800° 








3 


30 min. 


2.5 hr. 


1150-1200 


5 mm. 


4 


30 min. 


5.5 hr. 


1135-1155 


5 mm. 


5 


30 min. 


6.5 hr. 


1250 


less than 
1 mm. 


6 


In 20 min. raised to 1250° 
40 min., 1250-1350 


6 hr. 


1350 


less than 
1 mm. 


7 


30 min. 


4.5 hr. 


1680 


less than 
1 mm. 


8 


25 min. to 1530 


25 min. 


1535 


less than 
1 mm. 


9 


30 min. to 1520 


5 hr. 


1535 


less than 
1 mm. 


10 




9.5 hr. 


1650 


Less than 




1 mm. 


11 




12 hr. 


1650 


Less than 




1 mm. 


12 


30 min. 


2.5 hr. 


1865 


Less than 
1 mm. 


13 


25 min. 


2 hr. 


1760 


Less than 
1 mm. 


14 


25 min. 


1 hr. 


1760 


Less than 
1 mm. 



REMARKS. 

Exp. 1. Diamond completely destroyed. Product gave Brodie test. 

Exp. 2. Diamond No. 2. Light grey color. Transparent ; dark spot 
appeared in center. No superficial change. 

Exp. 3. Diamond No. 2. Dark grey. Filled with small dark spots. 
Small piece cracked off showed double refraction. This small sample 
contained a dark spot. 

Exp. 4. Diamond No. 2. No appreciable change. 

Exp. 5. Diamond No. 2. No superficial change. Looked darker. Alore 
internal dark spots. 

Exp. 6. Diamond No. 2. More spots and larger. Under microscope 
they had a brown color and spongy appearance. The dark color of tiie 
diamond seemed to be due to many cracks which totally reflected the 
light in air, but in the sulfur solution in methylene iodide the diamond 
was clear except for the spots. 

Exp. 7. Diamond No. 2. Completely black. Blackened paper slightly. 
The spots inside now black, not brown as at first. The black spots have 



CONVERSION OF DIAMONDS TO GRAPHITE. 



165 



a metallic luster when observed in reflected light under the microscope 
identical with that of graphite. 

Exp. 8. Diamond No. 3. Slightly grey. 

Exp. 9. Diamond No. 4. Turned black. 

Exp. 10. Diamond No. 2. Brittle and easily broken. Part of surface 
shiny, rest dull black. Blackened paper like a pencil. One small corner 
still transparent in small piece examined under microscope. Still hard 
enough to scratch steel. 

Exp. 11. Diamond No. 2. Diamond was cracked into a number of 
pieces. All treated with HNO3 and KCIO3. Small ones changed to 
graphitic acid. The large pieces did not dissolve, but were of lighter 
color. Total duration at 1650°, 26 hr. 

Exp. 12. Diamond No. 5. Black residue. Gave Brodie test. 

Exp. 13. Diamond No. 6. Diamond was split to pieces. 

Exp. 14. Diamond No. 7. Diamond appeared at about the same degree 
of change as No. 2 after 26 hr. at 1650°. Parts were found thrown out 
from the central hole in the plate, as though the diamond exploded. 



-i 




T| 


I U-*— H 


-JJ 










F.-g.a 




Fi 



•9 



Fig. 1. Diamond (D) in Graphite Crucible. 

Fig. 2. Diamond No. 7. Fragment of diamond lying with outside face uppermost. 
Heavy coating of graphite on the outside with numerous specks of graphite scattered 
through the still transparent but cracked interior. Heavy cross-hatching represents 
the graphite coated surface; the light represents the interior of the clear diamond, x 150. 

Fig. 3. Diamond No. 2 after E-xp. No. 7. Cleavage Face broken from diamond 
shows dendritic development of graphite on the face, as at "a," and the development 
along incipient cleavage planes, as at "b." Dots on edges are graphite developing in 
the interior of the diamond. Somewhat generalized, x 300. 



l66 DISCUSSION. 

DISCUSSIOX OF RESULTS. 

The above experiments show conclusively that diamonds change 
slowly at 1650° C. to a substance that gives the Brodie test. 
This change takes place about 26 times as rapidly by raising the 
temperature 100°. Diamonds turn dark at 1000°, but this is 
largely due to numerous cracks causing absorption of light from 
total reflection. The cracks were probably produced by the small 
black spots. These spots are doubtless the beginnings of change 
to graphite, producing strains and double refraction. Doelter 
also found double refraction in diamonds that had been heated. 
Experiments 8 and 9 show these cracks are not due alone to 
thermal expansion and contraction, for if they were the two 
diamonds would have had the same appearance. 



DISCUSSION. 



W. C. Arsem^ : There seems to be a great deal of confusion in 
regard to the nature of the different forms of carbon that we 
meet with. There is no question about what we mean by diamond 
or pure graphite. They are definite crystalline substances, and 
X-ray analysis has shown them to have definite molecular struc- 
ture and definite lattices. When we consider the different so- 
called amorphous carbons and so-called graphites of indefinite 
character, there is some doubt. 

It seems to me that when carbon is set free from an organic 
compound or derived from some different form by heat, if the 
conditions are not favorable for an arrangement or rearrangement 
of the atoms to form a definite crystalline structure, we must 
have a mixed lattice structure. 

Amorphous carbon derived from sugar will not have a definite 
crystalline structure. It will be a heterogeneous arrangement of 
atoms. You may have different characteristic groupings here and 
there throughout the whole mass or solid particle, but no definite 
repeated chain or pattern structure, such as you have in a crys- 
talline substance. In the same way we would expect, on heating 

' Consulting Chemical Engr., Schenectady, N. Y. 



COXVERSIOX OF DIAMONDS TO GRAPHITE. 167 

the diamond to temperatures far below the point of mobiHty, that 
the atoms can not rearrange themselves to form a definite lattice 
structure. So that we w-ould not expect to get pure graphite by 
heating the diamond any more than we would expect to get pure 
graphite, from heating certain amorphous carbon to a hio-h 
temperature. 

Xow, as to the Brodie test, I believe that when pure crystalline 
graphite is oxidized, that the so-called graphitic acid, the yellow 
organic substance which is formed, has a definite chemical struc- 
ture, and can be identified, but when obtained from a carbon with 
a mixed lattice structure, the same as v.e would expect to get 
on heating most amorphous carbons or the diamond, the yellow 
oxidation product does not have a definite structure. It may 
be a mixture of substances, or it may be a complex organic com- 
pound with a mixed lattice structure corresponding to the struc- 
ture of the carbon from which it is derived. 

The Brodie test, in the light of our present knowledge of 
molecular structure can not be regarded as a satisfactory test 
for graphite, or even for the presence of graphitic structure, 
until more is known of the chemical nature of the yellow oxidation 
products obtained with diflerent carbons. 

I presented a paper before the Society some years ago, and 
mentioned the heating of a diamond to 3,CXX)°. I found a specific 
gravity of the product that was about 1.8, whereas, pure graphite 
should have a specific gravity of 2.25. I do not think that pure 
graphite can result from heating the diamond under these con- 
ditions, and I do not believe that the data given in the present 
paper support that conclusion. 

CoLix G. FiXK- : I should like to refer briefly to experiments 
recently carried out at the laboratories of the Siemens-Halske 
Company.^ They started out with amorphous carbon in fine thread 
form, and heated this up to temperatures of 3,000 to 3,600°. 
What they obtained was a graphite of 2.23 specific gravity. 

They tested these fine filaments, and curiously enough they 
could be rolled, and their length extended by 10 per cent. Fur- 
thermore, they could take the filaments and wind them into a 

2 Consulting Metallurgist, New York City. 
3Z. Elektrochem. 29, 171 (1923). 



1 68 DISCUSSION. 

very small coil, and then straighten them out again just as though 
they were made of lead. 

F. A. J. FitzGerald* : I understand from Dr. Fink that the 
Siemens-Halske graphite filaments had a positive temperature 
coefficient of electric resistivity like the Gem filaments, on which 
Dr. Whitney was working some years ago at Schenectady. 

Does Mr. Arsem consider the Brodie test a definition of graph- 
ite as Berthelot suggested? It is probable that the best test for 
graphite is found in a study of the lattice structure by X-ray 
examination. 

W. C. Arsem : On some of the work on Gem filaments we 
produced a graphite with a specific resistance one-third that of 
mercury and a pronounced positive temperature coefficient. Some 
of this was produced in thin sheets that had the characteristics 
of tin foil and could be rolled up, but I never succeeded in rolling 
any of it thinner and extending its length. I had hopes of doing 
so, but about that time we lost interest in it, because the tungsten 
lamp looked more promising, and all efforts were devoted to that 
work. 

S. C. LiND^ : It seems to me the important thing in connection 
with this paper is, whether the spots that Prof. Thompson has 
found can be examined by the X-ray method. We agree it is 
perfectly satisfactory for graphite or diamond, but if it can not 
be used on the spots as they exist in diamond, I do not see that 
it would be of much use in that connection. 

I would like to mention one or two points in connection with 
some observations we have recently made. I do not wish to go 
fully into the matter because we are publishing the results in 
the Journal of the Franklin Institute next month. In connection 
with some work in the coloring of diamonds with alpha rays, 
we found under some conditions that "carbon spots" were pro- 
duced. I will not call these spots graphite, because we have not 
proved they are. The results were produced at ordinary tem- 
perature, showing that high temperature is not necessary to con- 
vert diamond into some other form of carbon. These spots were 
small, round spots in the interior of the diamond, which does not 

« FitzGerald Labs., Niagara Falls, N. Y. 

s Chief Chemist, U. S. Bureau of Mines, Washington. D. C. 



CONVERSION OF DIAMONDS TO GRAPHITE. 1 69 

support the idea that they are produced directly by alpha rays. 
In some instances they appeared to grow from a center. There 
was a halo surrounding the round spot, which made us think 
they grew from a center acting as a seeding point in the diamond. 
Furthermore, at the temperature of a blast lamp they disap- 
peared and reverted to diamond. Whether this reversion will 
satisfy Dr. Fink or not, I do not know, but it satisfied the jewelers 
who had furnished the diamonds, because otherwise they would 
have stood a considerable financial loss. These spots disappeared 
absolutely and went back to perfect diamonds, showing, I think 
for the first time, that there is some form of carbon other than 
diamond, which will revert, under conditions we have alwavs 
supposed were not characteristic of diamond in the stable form, 
into diamond. Whether or not this controverts the phase rule, 
I will leave to you to decide. 

Ancel St. John®: Regarding the question as to whether the 
X-ray would be able to tell about the change from diamond to 
graphite, I can say that it would. But I do not know how soon 
the work on this will be completed. 

I have on my desk a few rather small diamonds. They are 
unfortunately not as large nor as numerous as I would like to 
play with, but they will do. For with a very small quantity of 
material you can get results by the X-ray method which are 
incontrovertible. Thus, in a photograph of the pattern from 
diamond, A. W. HulF has obtained twenty-five of the twenty- 
seven lines calculated for the structure assigned to diamond, and 
in a pattern from graphite, nineteen of the forty lines required 
by its proposed structure. By mounting specimens in a dififerent 
way, I have recorded thirty of these graphite lines in a single 
pattern. 

One of the problems I want to attack when I get time is to 
find out just what happens to the crystal structure when a dia- 
mond is heated until it goes through some of the transformations 
mentioned. 

Colin G. Fink: Dr. Lind says you can get the spots at low 
temperature by the action of alpha rays on the diamond. Does 

" Union Carbide and Carbon Research Lab., Inc., Long Island City, N. Y. 
"Physical Review, 10, 695 (1917). 

12 



1 70 DISCUSSION. 

he mean to infer that in the Arsem furnace rays from the in- 
candescent crucible may have had some effect ? That it was not 
the heat alone, but radiation from the hot crucible that may have 
brought about the spots? 

S. C. LiND : I did not intend to draw such an inference. All 
I meant to point out was that it is evidently possible, under some 
conditions other than high temperatures, to change diamond into 
some other form of carbon. I did not mean to question Prof. 
Thompson's results. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 4, 1923, President Schlueder- 
berg in the Chair, 



THE RELATION BETWEEN CURRENT, VOLTAGE AND THE 
LENGTH OF CARBON ARCS' 

By A. E. R. Westman^ 

Abstract. 

An account of the early work on the electric arc has been given 
by Mrs. Ayrton^, and a summary of present knowledge by Stein- 
metz^. Each of these writers is the author of a formula connect- 
ing current, voltage, and arc length ; but in the experiments on 
which these formulas were based the currents only ran up to 30 
amperes or so, and it seemed desirable to add to the experimental 
material. The present paper gives an account of measurements 
made with currents up to 770 amperes. 



I. INSTRUMENTS AND APPARATUS. 

The voltage over' the arc was measured directly by a Weston 
model 45 voltmeter with scale 0-150 volts (Vj Fig, 1). In addi- 
tion, in order to get closer readings, a second voltmeter (Vo) of 
the same type but with scale 0-3 volts was used to measure the 
difference between the e. m. f. of a storage cell (B) and the p. d. 
over 70 ohms, forming part of a resistance of 1,000 ohms in paral- 
lel with the arc; in the run of March 8th referred to later, the 
voltage over the arc was given by the relation : 

e = 28.0 + 0.340 div. (1) 

where "div." is the reading Vg in fiftieths of a volt. 

The current was measured by a Weston millivoltmeter model 
45 (M Fig. 1) in conjunction with appropriate shunts (S). The 

' Original Manuscript received August 21, 1922. 

2 Department of Electrochemistry, Univ. of Toronto, Toronto, Ont. 

3 H. Ayrton, "The Electric Arc," Electrician Pub. Co., London, 1908 
* Chem. and Met. Eng., 22, 458 (1920). 

171 



172 



A. E. R. WESTMAN. 



millivoltmeter, the shunts, and the voltmeters mentioned above, 
were all calibrated by comparison with Weston standards. 

The current was derived from a 100 kw. 110 v. d. c. compound 
wound generator driven by a steam turbine in the power house of 
the University ; during my experiments no other load was carried 
on this generator. Owing to a breakdown in the power house, 
however, niany of the measurements (including those of March 
8th) had to be made with power supplied by the Toronto Electric 
Light Company. 

I I I U V. 

oooooooo 




Fig. 1 



The rheostat (R Fig. 1) in series with the arc consisted of ten 
parallel coils of No. 12 iron (telegraph) wire immersed in run- 
ning water. Each coil had a resistance when new of about half 
an ohm, and was provided with its own switch ; the resistance in 
series with the arc could thus be varied from 0.5 to 0.05 ohm. The 
relation between current /, and voltage over the arc, e, is given by 



= B — iR 



(2) 



where E is the voltage at the source of supply, and R the resistance 
of the rheostat. If the temperature of the rheostat wires, and 
hence their resistance, were independent of the current, and if 
there were no voltage drop in the leads carrying in the current, R 
and E would be constants, and the relation between current and 
voltage over the arc would be linear so long as the setting of the 
rheostat remained unchanged ; this is the relation assumed by Mrs. 
Ayrton and others in their work with low amperage. Under the 
conditions of my own experiments, however, the temperature of 
the rheostat wires was far from independent of the current, the 



THE LENGTH OF CARBON ARCS. 173 

water flowing hot from the wire box; and yet a graph of the 
200 current and voltage readings of the run of March 8th referred 
to below shows a straight line from ^ = 20 to ^ = 55 volts, with 
the equation 

e — 137.4 — 0.292 { (3) 

There were no greater variations (±3 per cent of the current) 
than can be ascribed to fluctuations in the line voltage, but this 
was in the neighborhood of 110 volts, not 137.4. The following 
discussion may serve to clear this matter up, although the simple 
conditions postulated below are of course not strictly fulfilled in 
practice. 

Since the heat generated in the rheostat was carried off by a 
constant flow of water, the average temperature of the latter 
would be : 

fw— fo= oRP (4) 

where t^ is the temperature of inflowing water, R the resistance 
of the wires, and a a constant depending on the rate of flow. 

When a steady state has been attained, the difiference between t 
(the temperature of the wires) and t_^ will be proportional to the 
flow of heat through the stationary film of water at their surface, 
or 

t - t^ = bRP (5) 

Finally, the resistance of the wires may be expressed by 

R = [I + c a — to )\ , Ro (6) 

where R is the resistance at the temperature t , and c the tem- 
perature coefficient of the resistance of iron wire. 

From equations 4, 5 and 6 may be found an expression for R 
as a function of the current ; this when introduced into equation 
(2) gives:— 

e = E - Roi / {I— c (a ^ b) Roi-\ = E — Ai; (1 — BP) (7) 

Setting £ r= 110, and choosing A and B so that for ^ = 20 and 
^ = 55 the values of i are those given by the empirical relation of 
equation (3), there results: 

^ = 110 — 0.1720 //(I — 1.403 X 10« r) (8) 



174 



A. E. R. WESTMAN. 



The following table gives for a number of values, of e, the values 
of i calculated from the rational formula (8) and those from the 
convenient empirical formula (3). Between 280 and 400 amperes, 
that is, while the p. d. over the cell varies from 55 to 20 volts, the 
greatest difference is 5 amperes ; thus for the purpose of calcu- 
lating the current, Mrs. Ayrton's straight line construction is accu- 
rate enough even though the conditions for which it was originally 
deducted are not fulfilled ; if it be used to calculate the potential 
difference from the current, however, an error of 1.4 volts would 
be introduced at c := 35. 

Table I. 



p. d. over arc 


Amp. Eq. 8 


Amp. Eq. 3 


Diff. 


110.00 


0.0 


94.0 


94.0. 


92.47 


100.0 


154.0 


54.0 


73.41 


200.0 


219.5 


19.5 


55.00 


282.5 


282.5 


0.0 


50.63 


300.0 


297.6 


— 2.4 


43.96 


325.0 


320.4 


— 4.6 


36.76 


350.0 


345.0 


- 5.0 


29.26 


375.0 


370.8 


— 4.2 


20.00 


402.5 


402.5 


0.0 



Assuming c = 0.0055 and /q = 10° C, the values and A and B 
chosen above lead to a temperature of 53° C. for the wire when e 
=z 55, and to a temperature just below 100° C. when e = 20. 
This corresponds to the experimental conditions ; for the amount 
of water sent through the rheostat was just sufficient to prevent 
rumbling with the heaviest current it was proposed to employ. 

The arc in my experiments was struck between a stationary 
vertical anode and a vertical cathode carried by a jib ; thus the 
cathode was always above the anode. Both electrodes were four 
inches in diameter and were manufactured from a petroleum coke 
base by the National Carbon Company. 

The jib holding the cathode was raised and lowered by an elec- 
tric winch motor set. Each revolution of the armature of the 
motor raised the jib 0.553 mm., and by attaching a Veeder revolu- 
tion counter to the armature the position of the electrode could 
be known to half a millimeter; owing to the great weight of the 



THE LENGTH OF CARBON ARCS. 175 

jib, 365 kg. (800 lb.), and smooth bearings, there was very Uttle 
slack. After trial, however, this method was discarded in favor of 
measurement with a cathetometer. This was an upright instru- 
ment provided with telescope and vernier, manufactured by Becker, 
Hatton Wall, London; it was sighted on a very fine line ruled 
with india ink on drawing paper attached to the cathode holder. 
Readings were made to 0.01 mm. which was closer than necessary, 
and perhaps rather beyond the accuracy of the instrument. 

II. CONDITIONS FOR A STEADY ARC. 

By far the greater part of the time so far devoted to this inves- 
tigation has been spent in finding conditions under which a steady 
arc can be maintained; for no measurements at all are possible 
unless the voltmeter readings are definite and show no variations 
except the steady rise due to the electrodes burning away. The 
principal difficulties met with and overcome were those due to air 
draughts, magnetic flux from the cables, eccentric arcs, "hum- 
ming," and "groaning"; minor difficulties, due to spontaneous 
shifting of the arc, still remain. Owing to the heavy currents used 
in my work, the disturbances from these sources were incompar- 
ably greater than those met with by previous experimenters. 

Air draughts: At first, a circular wall of sihca firebrick was 
built around the arc, no "bond" (mortar, etc.) being used in the 
construction ; then a top of firebrick was added, and as it appeared 
' that each added protection improved the arc, the brick wall was 
replaced by a steel furnace shell 76 cm. in diameter and 91 cm. 
high (30 X 36 in.) lined with clay firebrick and covered with large 
firebrick blocks and sheet asbestos. To increase the heat insula- 
tion, the space between lining and shell was filled with crushed 
firebrick. Finally, the iron column described below, which acted 
as magnetic shield, was almost closed at the bottom with brick. 
With this arrangement, the air draught was reduced to a slow, 
evenly distributed stream moving parallel to the electrodes ; any 
further reduction of the air supply resulted in irregular currents, 
which blew the arc sideways. 

Magnetic disturbances: An arc, being a flexible conductor 
carrying a current, is blown to one side by any magnetic flux at 
an angle to the direction of the arc. Such a flux was set up by the 



176 A. E. R. WESTMAN. 

loop of the circuit of which my arc was a part ; and as no conve- 
nient arrangement of the cables could be found with which the dis- 
turbance from this source was not noticeable, I resorted to the use 
of iron shields. After experimenting with various arrangements 
of iron pipes and sheets, satisfactory results were obtained by 
surrovmding the arc with a laminated iron column 38 cm. high 
(15 in.), 3.8 cm. thick (1.5 in.) and 30.5 x 30.5 cm. (12 x 12 in.) 
in (rectangular) cross section, built up of fifteen square iron 
window frames. The "magnetic shield" so constructed offers a 
path of low reluctance in the horizontal direction, and only after 
it was installed could the arc be steadied sufficiently for accurate 
readings. 

Centering the arc: If new electrodes be used, with ends turned 
flat in the lathe, it may be hours before the arc settles down to burn 
steadily in one place, and the crater thus formed is seldom in the 
center of the anode. If the anode surface be covered with pow- 
dered carbon, the arc chooses its final position more quickly, but 
seldom selects the center. If a small hole (10 mm. in diameter, 
15 mm. deep) be drilled in the anode, the arc will stay in that 
spot if it happens to run into it. 

Having obtained a centered arc by the use of such a hole, I 
allowed it to burn for six hours ; and using the resulting cratered 
anode and pointed cathode as patterns, turned a pair of new 
electrodes to the same shape and size in a lathe, making the crater, 
however, only about a quarter as deep as that of the used electrode. 
The anode was then mounted in the furnace and powdered carbon 
poured over it, filling the crater and covering the flat top to the 
depth of 5 or 6 mm. ; the carbon powder obtained by dusting off 
the electrodes after a run proved best for this purpose. When the 
arc was struck (using one coil, about 0.5 ohm, in the rheostat) it 
centered at once, and all the carbon dust burned out of the 
crater in a few minutes. In all subsequent experiments, artificially 
shaped electrodes were employed ; by the use of a tool made for 
the purpose in the University machine shop, the anode could be 
reshaped without removing it from the furnace. 

Lozv voltage arcs: When, after the arc had been struck as 
described, the current was increased by lowering the resistance in 



THE LENGTH OF CARBON ARCS. 177 

the rheostat, it often happened that the arc was blown to one side 
and extinguished. In the end I found that this could be avoided 
by lowering the cathode until the potential difference over the arc 
was only about twenty volts before raising the current to the 
desired amperage. 

The general belief, in which I shared, that an arc between car- 
bons cannot be maintained at less than about 40 volts, kept me 
from discovering this method sooner ; as a matter of fact, there 
is no difficulty in maintaining a 20- volt arc for well on to an hour 
under the conditions of my experiments. Both yirs. Ayrton's 
f ormula° : 

e = 38.88 + 2.074 / + (11.66 + 10.54 l)/i (9) 

and Steinmetz's formula" : — 

e = 36 4- 52 {I + 0.8)/\/T~ (10) 

contain a constant term (38.88 or 36 volts respectively) commonly 
referred to as the "counter electromotive force of the arc." These 
formulas are in good agreement with the results of experiment up 
to currents of thirty amperes, but it is obvious that if this inter- 
pretation is to be adhered to, the counter e. m. f. must decrease 
with increase of current. 

Humming arcs: When the arc gave out a humming noise (direct 
current, not alternating current was used,) inspection through col- 
ored glasses showed that it was flickering, /. e.. that the luminous 
part of the arc was enlarging and contracting periodically. A 
high note accompanies rapid pulsation of the arc, but very slow 
changes in volume (4 or 5 times per second) are inaudible. Once 
begun, the humming usually gets louder and louder, but without 
much change in note. 

In a humming arc the voltage over the electrodes oscillates ; if 
the hum is loud, the needle of the voltmeter is set in rapid vibration 
and may, in addition, swing over a range of 10 to 15 volts every 
couple of seconds. If the hum is not loud, voltage readings may 
be secured ; but instead of rising at the usual rate as the electrodes 

' Loc. cit., p. 184; / gives arc length in mm. 

•Trans. .\m. Inst. Elec. Eng. 25. 803 (1906), and Chem. and Met. Eng. 22. 462 
(1920). In equation (10) above / gives arc length in cm. 

13 



178 A. E. R. WESTMAN. 

burn away, the voltage may remain almost stationary for half an 
hour or more. Stationary voltage over the arc may be accepted as 
indicating an approaching hum. 

A humming arc always left the cathode with a very pointed tip, 
like those observed by ]\Irs. Ayrton in her "hissing arcs." The 
only cure is to shut off the current, cool the cathode, and rasp off 
the tip, preferably to a diameter of about 30 mm. (see below). 

Swinging arc: On one occasion I was bothered for days by an 
arc which emitted a note rising in pitch when the cathode was 
lowered and falling when it was raised. At first I took this for 
a "humming" arc, but reshaping the cathode failed to remove the 
trouble. In the end, a vertical saw cut through the anode, which 
had become elliptical in horizontal section, revealed a crack in the 
carbon across the bottom of the crater; the arc had travelled 
backwards and forwards along this crack, and dug out a trench 
with a craterlet at each end. 

Groaning arcs: When the arc is burning normally the whole 
crater is so hot that it is impossible to distinguish a specific anode 
spot; but if the arc groans, inspection shows that a white hot 
spot is jumping from the bottom to the edge of the crater and 
back again ; when the spot is on the edge, the arc is blown out- 
wards (away from the center of the crater) and the "groan" is 
heard. At first the spot stops only two or three seconds in each 
position ; but this period soon lengthens, rising in four or five 
minutes to about ten seconds, whereupon the groan rises to a 
shriek, and the arc is extinguished. 

In a groaning arc the voltage over the electrodes falls about 
thirty volts each time the anode spot reaches the edge of the 
crater, and rises again when it returns to the bottom. 

It is evident that an arc can "groan" only if the cathode is too 
near the edge of the crater in comparison with its distance from 
the bottom. The groaning can be stopped (1) by making the 
cathode narrower at the point, (2) by widening the crater 
throughout, (3) by bevelling the edge of the crater, thus making 
the latter wider at the top, or (4) by cutting down the edge of the 
crater, thus making the latter more shallow. All four methods 
have their limitations. If the cathode is too narrow at the tip, the 



THE LENGTH OF CARBON ARCS. 



179 



arc will hum ; if the crater is too wide, 
the arc will burn small craterlets in 
the bottom and jump from one to the 
other; if its walls are too much bev- 
elled, the same thing will occur; and 
if the crater is too shallow, the arc will 
not remain in it. Electrodes cut to the 
dimensions of the accompanying sec- 
tion (Fig. 2), which is drawn from 
the templates used in the laboratory, 
will give a good arc for 4 or 5 hours 
with currents up to 300 or 400 
amperes. 



III. 





Fig. 2 



DIRECT DETERMINATION OF 
ARC LENGTH. 

In Mrs. Ayrton's work the "length 
of the arc" was defined to be the verti- 
cal distance between the point of the 
cathode and the horizontal plane drawn 
through the edge of the crater ; length 
zero did not mean that the carbons 
were in contact, but that the point of 
the cathode was just entering the 
crater. It is obvious that in an arc 
between unformed carbons burning with constant current 
and "constant arc length" so defined, the vertical distance 
between the electrodes will not be constant at all, but will keep 
increasing until the crater attains its final dimensions. This did not 
escape Airs. Ayrton, who studied the changes in voltage accom- 
panying the formation of the crater ; nevertheless, she adhered to 
her own definition of "I" and measured it on an image of the 
arc projected by a lens. In my own work, the depth of the crater 
was such a large fraction of the whole distance betvveen the elec- 
trodes — it often reached 35 mm., while the total length never 
exceeded 60 mm. — and the voltage so evidently depended on the 
total length and not on that above the crater's edge, which more- 
over with my high currents was too irregular to afford a fixed 



l8o A. E. R. WESTMAN. 

point for the measurements, that I decided to measure the total 
vertical length as the "length of arc." This quantity, of course, is 
greater than Mrs. Ayrton's "T ; to avoid confusion I indicate it by 
the capital letter "L". 

Measurement of L: When a steady arc had been secured the 
height of the cathode was determined (by revolution counter or 
cathetometer), voltage and current were read, and the circuit 
broken. To protect crater and tip from burning away, powdered 
carbon was then poured down a pipe into the crater, and the 
cathode was lowered until its tip was also protected by the powder. 
The furnace was then allowed to cool (about ten hours was 
required), the carbon was blown out, the height of the cathode 
measured again, and a plastic ball of moistened fire clay was 
squeezed into place so as to take an impression of crater and tip. 
When the clay had hardened, the length of the arc when the cir- 
cuit was broken {L, as defined above) was determined by caliper 
measurements of the clay model plus the difference between the 
two cathetometer readings. With care, such measurements can 
be made within a millimeter or two; if the electrodes are too hot, 
the surface of the model will be rough ; if they have cooled to 
room temperature, the clay takes three or four hours to harden, 
and a good model results. 

Every such measurement involved shutting down the furnace 
for at least twelve hours ; I have obtained, so far, eight fairly 
good results, besides a number of failures. In Table II, those 
marked with a star were measured with the cathetometer, the 
other two with the revolution counter. 

For comparison, the values of / from Mrs. Ayrton's formula 
(Eq. 9) ancl from Steinmetz's formula (Eq. 10) are given in 
Table II, both of them in millimeters. 

IV. DETERMINATION OF CHANGES IN VOLTAGE CONSEQUENT ON 
KNOWN CHANGES IN ARC LENGTH. 

With a view of obtaining results more rapidly, it was decided 
to measure the changes in voltage caused by lowering or raising 
the cathode small measured distances. Such determinations should 
give a series of values of dc/dL (or dc/dl, which is the same thing) 



THE LENGTH OF CARBON ARCS. 



I8I 



under the condition that di = — k.de (see Eq. 3) ; from these 
by integration, using results with the clay model as integration 
constants, the relation between e and L might be determined. A 
number of fairly good runs were made with currents from 300 
to 400 amperes, of which that of March 8, 1922, was the best, 
i. e., showed the smoothest burning arc. Four others were made 
with currents from 700 to 800 amperes, but in none of them 
was the arc steady enough to give satisfactory results by this 
method ; I hope to get better results soon. 



Table II. 



amp. 



280 
*311 
*350 
*385 

390 
♦712 
*732 
*770 



148 X 10' 
135 X 10" 
147 X 10' 
119x10^ 
168 xlO' 
356 xlO' 
315x10- 
262 x lO' 



volts 



53.0 
43.5 
42.0 
31.0 
44.5 
50.0 
43.0 
34.0 



L 

mm. 



56 
42 
42 
30 
42 
55 
49 
43 



/ Ayrton 


/ Steinmetz 


mm. 


mm. 


6.7 


• 46.7 


2.2 


17.4 


1.5 


13.6 


- 3.8 


—10.9 


2.1 


24.2 


5.42 


63.8 


2.0 


28.4 


— 2.3 


2.7 



In each of these runs, current, voltage over the arc, and "divi- 
sions" on the second voltmeter were recorded every minute ; Table 
III gives "divisions" and time in minutes after striking the arc 
for the run of March 8th ; the voltage over the arc can be obtained 
from the number of divisions by means of Eq. (1), and the cur- 
rent by Eq. (3). Below 28 volts the second voltmeter could not 
be used ; the numbers entered in Table III under "volts" give 
the readings of the first voltmeter (scale 0-150 volts). 

Table IV gives the cathetometer readings (in millimeters) for 
March 8th ; when the cathode was raised the cathetometer reading 
increased. At ^ = 57, i. e., 57 minutes after striking the arc, the 
cathode was moved to the left in the hope of steadying the arc; 
at t = 111, it was moved again to the left to stop humming; at 
^ = 138 it was shifted again to stop groaning. The effect on arc 
length caused by these movements can only be guessed. 

For ^ = 231, a clay model gave L = 42 mm. ; values of L for 
other values of t (above t = 138) were calculated from the cathe- 



1 82 



A. E. R. WESTMAN. 



tometer readings, C, on the assumption that the carbons burn 
away at the uniform rate of 9.0 mm. per hour irrespective of 
the wattage. Thus for 138 < f ^ 231 L =: C —782.6 + 0.15 ^ 



Table III. 



Time 




Time 




Time 




Time 




Time 




Time 




min. 


Volt 


min. 


Div. 


min. 


Div. 


min. 


Div. 


min. 


Div. 


min. 


Div. 


17 


21.2 


50 


14.8 


87 


52.0 


121 


60.0 


156 


70.0 


197 


38.0 


18 


21.2 


51 


15.0 


88 


53.0 


122 


42.5 


157 


70.5 


198 


38.0 


18 


21.2 


52 


34.2 


89 


54.0 


123 


43.5 






199 


38.0 


19 


21.2 


53 


33.5 


90 


40.2 


124 


43.8 


165 


71.5 


200 


37.5 


20 


21.3 


54 


34.0 


90 


35.0 


125 


45.5 


166 


73.0 










55 


34.0 






126 


47.0 


167 


73.5 


201 


17.0 


21 


21.7 


56 


44.0 


91 


380 


127 


48.2 


168 


74.5 


202 


17.0 


22 


21.9 


59 


44.5 


92 


40 


128 


4S.0 


169 


75.5 


203 


17.5 


23 


21.6 


60 


44.8 


93 


41.2 


129 


48.0 


170 


53.0 


204 


18.0 


24 


21.5 






94 


42.0 


130 


48.5 






205 


18.5 


25 


21.6 


61 


45.0 


95 


43 






171 


53.5 


206 


44.0 


26 


21.6 


62 


45.9 


96 


70.0 


131 


49.2 


172 


54.0 


207 


43.0 


27 


23.7 


63 


46.2 


97 


69.5 


132 


49.8 


173 


54.5 


208 


43.0 


28 


24.0 


64 


46.5 


98 


69.5 


133 


51.0 


174 


55.0 


209 


42.5 


29 


24.2 


65 


47.0 


99 


69.5 


134 


230 


175 


37.0 


210 


42.2 


30 


28.6 


66 


47.2 






135 


23.7 


176 


39.5 










67 


37.0 


leo 


69.5 
59.5 
60.5 
61.0 


136 


25.5 


177 


44.5 


211 


42.5 


min. 


Div. 


68 


36.5 


137 


27 


178 


45.0 


212 


42.5 


31 


3.0 


69 


37.5 


101 
102 
103 


139 


15.0 


179 


46.0 


213 


4.0 


32 
33 


3.5 
3.5 


70 


38.0 


140 


17.0 


180 


46.0 


214 
215 


3.5 
3.5 


34 


5.7 


71 


38.5 


104 


62.2 






181 


47.0 


216 


3.5 


35 


6.1 


72 


39.2 


105 


63.0 


141 


18.0 


182 


47.5 


217 


4.0 


36 


7.0 


73 


39.4 


106 


63.0 


142 


19.0 


183 


28.0 


218 


4.5 


37 


79 


74 


40.5 


107 


40.5 


143 


19.5 


184 


29.0 


219 


27.5 


38 


8.5 


75 


40.7 


108 


43.0 


144 


20.0 


185 


30.0 


220 


28.5 


39 


9.0 


76 


40.5 


109 


46.0 


145 


20.0 


186 


31.5 










77 


50.0 


110 


49.0 


146 


20.5 


187 


32.5 


221 


29.0 


40 


10.0 


78 


51.0 






147 


48.0 


188 


33.2 


222 


30.0 


41 


10.2 


79 


52.0 


112 


54.5 


148 


47.0 


189 


34.5 


223 


31.0 


42 


10.6 


80 


52.7 


113 


55.0 


149 


46.5 


190 


7.0 


224 


2.0 


43 


11.0 






114 


56.0 


150 


46.5 






225 


2.0 


44 


12.0 


81 


53.8 


115 


57.0 






191 


7.0 


226 


2.0 


45 


12.0 


82 


43.5 


116 


55.2 


151 


47.0 


192 


7.2 


227 


2.0 


46 


12.5 


83 


47.2 


117 


58.0 


152 


47.5 


193 


7.8 


228 


45.5 


47 


13.0 


84 


48.5 


118 


58.5 


153 


48.0 


194 


8.0 


229 


45.0 


48 


13.8 


85 


50.0 


119 


59.0 


154 


70.0 


195 


8.2 






49 


14.0 


86 


51.0 


120 


60.0 


155 

1 


70.0 


196 


37.5 


231 


44.5 



For 110 < ^ < 139, I have replaced the subtrahend 782.6 by 
780.4, thus making an allowance of 2.2 mm. for the adjustment of 
the cathode at t — 138. For 58 < f < 139, the subtrahend 783.1 
is used, which is within half a millimeter of the first. Before 



THE LENGTH OF CARBON ARCS. 



183 




1 84 



A. E. R. WESTMAN. 



t =z 57, the subtrahend is 788.1. These last three values had to be 
chosen arbitrarily, and there is no independent check, as the adjust- 
ment consisted in moving the cathode sideways in order to secure 
a steady arc ; but the value employed for calculating the last hour 
and a-half of the run was obtained from the direct determination 
with the clay model. 

Table IV. 

Note: The cathode was moved to give the new cathetometer reading 
C millimeters about half a minute after the time entered under t. 



t 


c 


t 


C 


t 


C 


16 


806.4 


107 


809.4 


183 


792.1 


27 


809.3 


111 


(moved) 


190 


783.8 


30 


813.0 


112 


819.4 


196 


791.3 


52 


812.8 


122 


804.6 


201 


785.6 


57 


(moved) 


134 


795.2 


206 


791.7 


59 


817.9 


138 


(moved) 


213 


780.5 


67 


812.4 


139 


794.3 


219 


786.8 


77 


816.7 


147 


802.7 


224 


778.8 


91 


811.0 


154 


810.9 


228 


790.0 


96 


820.9 


170 


801.8 


231 


(model) 


101 


815.4 


175 


797.3 







Fig. 3 reproduces the data of Table III, with scales of voltage 
and current. The lines are "calculated" values, based on the 
assumption that a change of one millimeter in L causes a change 
of 3 divisions, or 1.02 volts, in the potential difference over the 
arc. In most cases where the voltage rises or falls more than on 
this assumption should correspond to the movement of the cathode, 
the instantaneous change is followed by a slower movement 
towards the calculated value ; the obvious explanation is that the 
points of origin of the arc, or one of them, have shifted along 
the electrodes. At / = 90 there is direct evidence of such a shift- 
ing of the arc ; the cathode was lowered 5.7 mm. and the voltage 
dropped 4.8 volts at once, but within half a minute fell another 1.7 
volts, most of which was recovered in the next couple of minutes ; 
and at f ^ 82 there was a sudden drop of 3 volts without any 
motion of the cathode at all, this again was quickly recovered. 
The figure also gives examples of the stationary or falling voltage 
which accompanies humming, for instance at t = 140, 180, and 
204; between ; = 157 and / = 175 the humming was so loud that 
no voltage readings could be secured. 



THE LENGTH OF CARBON ARCS. 1 85 

Taking the results as a whole, there can be no doubt that the 
assumptions made are justified at least as a good first approxima- 
tion ; and that for currents between 300 and 400 amperes, where 
e = 137 A — 0.292 i, de/dL is very close to one volt per milli- 
meter. Mrs. Ayrton's formula (Eq. 9) by differentiating and 
introducing the relation between current and voltage given in 
Eq. 3, leads to de/dl =: 2.1 volts per mm., and although L is 
different from /, the changes in these two quantities consequent on 
raising or lowering the cathode are the same. Steinmetz's formula 
(Eq. 10) leads to dc/dl = 0.33 volt per mm. for 300 amperes, 
and 0.44 for 400 amperes. Thus these two formulas, while in 
accordance with the experimental results up to 30 amperes or so, 
can evidently not be relied upon for currents of 300 amperes or 
more. 

SUMMARY. 

Conditions have been found under which a steady arc can be 
maintained between carbon electrodes with currents of 300 to 
400 amperes, and a fairly steady arc with currents up to 800 
amperes. Humming, swinging and groaning arcs have been 
described, together with a way to avoid them. 

A 20-volt arc can easily be maintained, and has been intro- 
duced as part of the routine of building up the arc. 

A straight-line construction may be used to represent the rela- 
tion between current and potential difference over the arc when 
the rheostat consists of water-cooled iron wire. 

Direct determinations of the distance between the electrodes for 
various currents and voltages have been made by the use of 
cathetometer and clay models. 

Changes in the voltage caused by raising or lowering the 
cathode for measured distances have been determined. 

For currents between 300 and 400 amperes and potential 
difference over the arc 55 to 20 volts, the p. d. in volts is approxi- 
mately equal to the distance between the electrodes in millimeters ; 
for currents of 700 amperes or so the voltage is less than the 
distance. 

The formulas proposed by I\Irs. Ayrton and by Steinmetz for 



1 86 DISCUSSION. 

low currents are not in agreement with the experimental results 
for high currents. 

These experiments were carried out in the Electrochemical 
Laboratory of the University of Toronto dtaring the winter of 
1921-22 ; my thanks are due to Professor W. Lash Miller for the 
interest he has taken in the work. 

University of Toronto, 
August, 1922. 



DISCUSSION. 

F. G. Dawson^ {Communicated) : It would appear that some 
variables in the environment of an arc not recorded in this paper 
might affect its characteristics. The temperature of the enclosure 
and the constancy of conditions of the gaseous atmosphere in 
the enclosure are certainly not without effect on an alternating 
current arc. In operating the experimental indirect arc steel fur- 
nace of the Bureau of Mines- the writer was impressed by the 
marked efifect of these two factors on the stability and length of 
the a. c. arc. There was a critical temperature in the preheating 
of the empty furnace, below which the arc would not hold steadily 
without constant electrode adjustment, but above which its sta- 
bility was high. 

If the furnace was luted up so as to avoid any draft at all 
within the furnace, and consequently to build up a slight pressure 
within the furnace, and to avoid any sudden influx of air, the 
temperature at which the arc became fully steady was lowered. 
An opening the size of a pin head would allow change of pressure 
and change of the composition of the atmosphere, with tiny fluc- 
tuations of the arc due to disintegration of the graphite electrode, 
which would notably increase the voltage necessary to hold the 
arc. It is not certain that the results obtained by Mr. Westman 
would have been the same in the absence of a positive flow of air. 

At operating temperatures, a tiny opening had no appreciable 

» Detroit Electric Furnace Co., Detroit, Mich. 

t H W. Gillett, and E. L. Mack, Experimental production of certain alloy steels. 
Bur. Mines Bull. 199, 1922, p. 14. 



THE LENGTH OE CARBON ARCS. I87 

effect on the Bureau of Mines' steel furnace, and when the fur- 
nace was so hot that ionizing vapors were present by volatilization 
from the refractories, or at a much lower temperature if sodium 
silicate had been used in repairing the lining, the voltage required 
to hold the arc would fall off to certainly well under 20 volts. 

There is no statement in the paper as to whether or not the 
lining glazed or showed any signs of decomposition, but the empty 
furnace used must have been very hot after running 6 hr. From 
Fig. 3, one would calculate that some 80 Kw.-hr, had been put 
into the furnace. 

The current density in the electrodes, and their composition, 
i. e., whether carbon or graphite, must affect the temperature of 
the electrode tips. With a positive flow of air, the burning away 
of the fip must have altered conditions throughout the run. 

If Steinmetz's experiments were done in a fairly tight enclo- 
sure, the differences between his formula and Mr. Westman's 
results may be at least partly accounted for. 

Electric furnace men would welcome a similar study of a. c. 
arcs in which not only the variables studied by Mr. Westman on 
d. c. arcs, but also the others mentioned above, are included. 

A. E. R. Westman {Communicated) : The work presented 
was undertaken as a necessary preliminary to the study of arcs 
under such practical conditions as high current densities, graphite 
electrodes, alternating current, etc. An experimental study of 
these factors is now under way in this laboratory. 

In Dr. Steinmetz's experiments^ he presented his equation as 
an approximation, and added that more recent and extended 
investigation seems to show that it is not rigidly correct. My 
conditions were in accordance with Steinmetz's definition of a 
normal arc, in which no mention is made of the degree of ioniza- 
tion of the surrounding gases. There seems to be no good reason 
to believe that such ionization would affect a heavy current arc, 
or that it would be materially increased by partially surrounding 
the arc with screens as in my experiments. 

Mr. Dawson reports that with a furnace thoroughly sealed, he 
found no trouble from air draughts in his apparatus. The top 
of the magnetic shield was quite open, and when I sealed it at 

' Chem. and Met. Eng. 22, 248, (1920). 



1 88 DISCUSSION. 

the bottom, down draughts and irregular currents interfered. 
Mr. Dawson's data and his description of his work with an en- 
closed arc are welcome ; there is next to no information of this 
kind in the literature. 

There is no statement in miy paper to the effect that 20 volts 
is the minimum voltage for holding an arc. With electrodes 
shaped as shown on page 179, it is evidently impossible for L (as 
defined on page 180) to be less than about 15 mm. For this reason 
I have not been able to run below 17 volts. 

J. Kelleher* {Communicated) : On pages 175 and 176, Mr. 
Westman describes a magnetic shield used to eliminate the effect 
of magnetic disturbances caused by the electrical circuits of the 
furnace. As no drawing is given showing the position of this 
shield with regard to the arc, I shall suppose that the arc was 
formed midway between the top and bottom of the shield. It 
seems to me that if this were the case, then with a mean furnace 
input of about 20 kw., (see Table II) the temperature of these 
laminations would soon rise and reach that point at which iron 
loses its magnetic properties. This I believe to be about 780° C. 
If this happened, the shield would be of little value, except when 
the furnace was cold. It would be of interest in this relation 
to know if the shielding effect decreased as the furnace tempera- 
ture increased. In my own work on arcs I found great difficulty 
in maintaining a long steady arc until the electrodes between 
which the arc was formed and the surrounding furnace walls, 
etc., had reached a high temperature. 

If this is not the case this same shield which I imagine consists 
of cast iron might be responsible for the humming arcs as de- 
scribed on page 177. If some variation in the current occurred, and 
a certain amount of residual magnetism was present in the shield, 
oscillations in the current might be set up causing an alternating 
potential which would increase or decrease the volume of the arc 
core, this again increasing or decreasing the volume of the gas 
surrounding the core. If an oscillograph were connected in the 
furnace circuit to indicate both current flowing and the potential 
across the arc, the humming arc and perhaps the groaning arc 
might be explained. 

* Cliippawa, Ont., Canada. 



THE I.ENGTH OF CARBON ARCS. 1 89 

The use of a cathetometer seems slightly in excess of the re- 
quirements of accuracy, as I notice no corrections have been made 
for thermal expansion in the determination of "h" on page 180. 

This interesting work I hope will be continued, and instead of 
using two carbon electrodes a bath of some metal such as iron 
might be substituted for the anode and a comparison made of the 
behavior of the arcs as described and those occurring where the 
anode is a metal. 

A. E. R. Westman (Communicated) : The magnetic shield 
did not reach a temperature higher than 800° C. in most of these 
runs, as there was always a current of air between the arc and 
the shield. I can not say whether the shielding effect decreased 
•during a run, as other circumstances such as the deepening of the 
crater tended to make the arc unsteady near the end of a run. 

The cathetometer was used more especially for measuring the 
movements of the cathode, which were sometimes as small as 
4 mm. ; these movements would cause no appreciable change in 
the temperature of the electrodes, and so no error from thermal 
expansion would be introduced. However, these results are only 
a first approximation, the results of more accurate measurements 
will be reported later. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 4, 1923, President Schlueder- 
berg in the Chair. 



ELECTRIC FURNACE DETINNING AND PRODUCTION OF 
SYNTHETIC GRAY IRON FROM TIN-PLATE SCRAP.' 

By C. E. Williams, 2 C. E. Sims,^ and C. A. Newhall> 

Abstract, 
Experiments were conducted in a small electric furnace in 
which tin-plate scrap was melted with various addition agents 
in attempts to remove the tin from the iron. Sodium chloride, 
iron sulfide, and an oxidizing slag were used under various con- 
ditions. The conclusions reached were that in the electric furnace 
complete detinning is impossible, and any detinning impractical. 
Melting tests conducted in the cupola showed that the amount 
of detinning was dependent upon the amount of surface of 
metallic tin exposed to the oxidizing gases, and will be somewhere 
between the limits of and 50 per cent. Test bars, prepared by 
melting pig iron with various quantities of tin, were subjected to 
physical tests. The results showed that a tin content of one per 
cent or less did not seriously afifect the properties of gray iron. 
Synthetic cast iron made from tin-plate scrap was used success- 
fully in making commercial castings of good quality. 



INTRODUCTION. 

The investigation here described was conducted at the North- 
west Experiment Station of the U. S. Bureau of Mines, in co- 
operation with the College of Mines of the University of Wash- 
ington, The object of the study was to determine the possibilities 
of converting tin-plate scrap or used tin cans into a marketable 

* Published by Permission of the Director, U. S. Bureau of Mines. Manuscript 
received February 1, 1923. 

2'' Metallurgist and Electrometallurgist, respectively, North-west Experiment Station, 
U. S. Bureau of Mines, at Seattle, Wash, in cooperation with College of Mines, 
University of Washington, 

* Washington Electrochemical Co., Seattle, Wash, 

191 



192 C. E. WILLIAMS, C. E. SIMS AND C. A. NEWHALL. 

Steel or iron product by electrothermal means. ^Nlost of the 
tin-plate scrap produced in this country is detinned and subse- 
quently melted in the open-hearth furnace, producing steel ; a 
small quantity of it is melted with other iron scrap in the cupola 
for the manufacture of sash weights and similar low-priced 
castings ; and some is used in certain hydrometallurgical plants 
to precipitate metals from solutions. A small quantity of used 
tin cans is treated similarly to tin-plate scrap, as above described. 
There are three established methods of detinning, namely : the 
chlorine, electrolytic alkali and the alkali-saltpeter processes, pro- 
ducing respectively tin tetrachloride, metallic tin and tin oxide. 

A plant utilizing one of the established detinning processes, to 
be profitable, must be operated on a comparatively large scale, 
the minimum capacity having been variously estimated as between 
50 to 100 tons of tin-plate scrap per day. In some localities 
the quantity of tin-plate scrap or old cans available may be so 
small, or the market for the recovered tin so limited, that another 
process of utilizing these waste materials would be required. In 
districts near can factories there may be an oversupply of tin- 
plate clippings and punchings, and in cities where efficient meth- 
ods of collecting old cans are in vogue, such materials may be 
available at much lower prices than the cost of steel scrap. In 
such cases a method of using this cheap form of iron in a more 
profitable manner than for conversion into sash weights would 
be desirable. 

The weight of the tin coating on tin plate varies between wide 
limits. Results of the analysis by the National Canners' Asso- 
ciation^ of many thousands of cans showed weights of from 0.53 
to 6.37 lb. of tin per base box containing 112 sheets and weighing 
100 lb., the grand average of all analyses being from 0.81 to 
2.94 lb. per base box. During the past few years,® the tin re- 
covered by detinning clean tin-plate scrap amounted to 1.6 lb. 
for each 100 lb. treated. Hence, assuming a recovery of 95 per 
cent, the average tin content of tin-plate scrap would be 1.7 
per cent, which probably represents the average content fairly 
closely. The tin content of used cans will be usually found a 

* Relative value of dtflFerent weights of tin coating on canned food containers. 
National Canners' Assn., Washington, D. C, 1917. 

"Secondary Metals in 1919, 1920, and 1921. J. D. Uunlap. Mineral Resources of 
the United States. U. S. Geological Survey. 



DETIXNING OF TIN-PLATE SCRAP. I93 

few tenths less than this, due to losses by mechanical abrasion 
and by solution in the foodstuff contained in the can, although 
if solder were used in sealing the can the tin content might be 
above 1.7 per cent. 

Not much information is available regarding the effect of tin 
upon the properties of steel or cast iron. In detinning, the 
attempt is made to produce a product containing less than 0.1 per 
cent tin, although during the war this limit was not insisted upon 
by purchasers of detinned scrap. In the present investigation no 
time was spent on chemical or electrolytic detinning, but attempts 
were made to remove the tin by some action during the process 
of melting the scrap. The impracticability of removing a large 
proportion of the tin in this manner was soon determined, and 
a study was then made to determine the possibilities of using 
tin-plate scrap in producing gray iron without removing the tin. 
With this in view a study was made of the effect of various 
quantities of tin on the properties of gray iron. 

EXPERIMENTS ON DETINNING. 

The physical and chemical properties of tin and its compounds 
are such as to offer little encouragement to the possibility of 
detinning iron in the electric furnace. The popular belief, that 
tin is volatilized when iron containing it is melted, is not founded 
on fact, because the boiling point of tin is 2270'' C. Tin is found 
in gases from cupolas in which tin-plate scrap is being melted, 
but its presence is probably due to the burning of the tin to 
oxide which is then carried mechanically through the stack by 
the escaping gases. Although the melting point of tin is only 
232° C. and that of iron 1500° C, the tin coating on most tin 
plate is so thin that the tin, although above its melting point, will 
not flow off and thus permit separation. 

The volatility of the chlorides of tin suggests the use of sodium 
chloride. The reaction would require oxidizing conditions and 
would undoubtedly produce stannous chloride whose boiling point 
is 603° C. The most obvious time to conduct this reaction would 
be before fusion of the iron, in order to permit the maximum con- 
tact of salt and air with the tin coating. The facts that stannous 
sulfide boils at 1230° C. and that it can be made by the action 



194 C. E. WILUAMS, C. E. SIMS AND C. A. NEWHALL. 

of iron sulfide on metallic tin offer the possibility of detinning 
with pyrite. The reaction would have to be complete enough to 
permit the use of only a slight excess of pyrite and thus avoid 
the introduction into the iron of too much sulfur. 

It has been suggested that detinning could be accomplished by 
melting under an oxidizing slag, thereby oxidizing the tin and 
slagging it off. Complete removal of the tin, however, could 
not be expected by this means, because tin is lower in the electro- 
motive series than iron and would be kept in a reduced condition 
by the metallic iron. Tin is soluble in iron up to 19 per cent,^ 
and hence, molten tin-plate scrap would contain tin in a dilute 
solution (about 1.7 per cent), which would contribute to the 
difficulties of removing it by a chemical reaction. 

A preliminary study of the reaction with salt at a temperature 
below the melting point of iron was first made. Strips of tin 
plate placed in fire clay roasting dishes were heated in a muffle 
and treated with fumes of sodium chloride. Tin was volatilized 
at temperatures above 500° C. when the atmosphere was kept 
strongly oxidizing, but the resultant iron sheet was badly oxidized 
and unfit for conversion into steel or iron. 

The subsequent tests were carried out in a basic-lined single- 
phase series-arc stationary furnace. The hearth was 23 x 38 cm. 
(9 x 15 in.) in cross section and conveniently held the 50-lb. 
charges used. Test No. 4 was made in a carbon-lined, direct- 
heating, single-arc, stationary furnace. The tin-pjate scrap, 
which consisted of clippings and rejected can ends, varied greatly 
in tin content and much difficulty was had in obtaining true sam- 
ples of the charges to the furnace. A fairly uniform feed was 
obtained by using only the can ends of uniform gauge. 

Numerous analyses showed that the average tin content was 
1.25 per cent, although the tin content of some charges probably 
varied as much as 10 or 15 per cent from this average value. 
Hence, great accuracy is not claimed for the results given below, 
which show the extraction of tin obtained by the dift'erent treat- 
ments. However, these results do show approximately the mag- 
nitude of the detinning obtained, and the relative effectiveness of 
the various methods tried. In order to make the results compara- 

'Tammann, Z. f. anorgan. Chem., 53, 281-295 (1907). 



DETINNING OF TIN-PLATE SCRAP. 



195 



ble, the conditions were kept as nearly uniform as possible in 
all tests. The furnace was preheated before charging and the 
molten charge held in the furnace for at least a half hour in 
order to superheat the metal and permit any reactions to go to 
completion. 

Tin-plate scrap was first melted with carbon in the electric 
furnace. The results, one of which is entered in Table I, show 
that no tin was removed by the treatment. A series of experi- 
ments using sodium chloride with various other reagents was 
conducted. A large excess of salt, amounting to 10 per cent of 
the weight of the scrap was charged with the scrap into the 
furnace. In some cases reducing and in others oxidizing condi- 
tions were maintained during the test. Table I shows the essen- 
tial data of these experiments. 



Table I. 
Tests on Chloride Volatilization. 





Charge 


Tin 
in 
pig 
per 
cent 


Per 

cent 

tin 

removed 




Run 
No. 


Tin 
plate 
scrap 

lb. 


Salt 
lb. 


Iron 
ore 
lb. 


Sili- 
ca 
lb. 


Carbon 
lb. 


Remarks 


1 

2 

3 

4 

5 

6* 

7 

8 


50 
50 
50 
50 
50 
50 
50 
50 


5 
5 

5 

5 
5 
5 


is 

15 

15 

5 




3 
3 


4 
4 

4 

Carbon 
lining 


1.25 
1.20 
1.22 
0.96 
1.13 
0.74 
1.02 
1.02 



4 
2 
23 
10 
41 
18 
18 


Reducing 
Reducing 
Reducing 

Slightly oxidizing 

Oxidizing 

Oxidizing slag 

Oxidizing slag 

Oxidizing, then 

reducing 



• This charge forced its way out of tap hole before the run was complete. 

Practically no tin was removed by melting with salt and carbon, 
the reducing atmosphere caused by the carbon undoubtedly pre- 
venting the formation of tin chloride. About 23 per cent of 
the tin was volatilized by melting the mixture of tin-plate scrap 
and salt without carbon, and about 10 per cent elimination of 
the tin was effected using an oxidizing slag. In two tests, using 
an oxidizing slag with sodium chloride, 18 and 41 per cent of 
the tin was removed, but the larger result can not be stressed 



196 



C. E. WILLIAMS, C. E. SIMS AND C. A. NEWHALL. 



too much because the furnace was tapped before the charge was 
completely melted. In no case was the elimination of tin com- 
plete or the results encouraging enough to give promise of success 
on a larger scale. 

The results of the experiments in which the attempt was 
made to volatilize the tin as sulfide are summarized in Table II. 
^Mixtures of tin-plate clippings and pyrites in various ratios were 
melted with carbon. In one case gypsum was substituted for 
pyrite. Runs 9 and 10 show that both the elimination of tin 
and the amount of sulfur introduced into the iron are propor- 
tional to the amount of pyrite used. The removal of the tin was 



Table II. 
Tests on Sid fide Volatilisation. 











Charge 








Analysis 


Per 
cent 
tin 


Run 


















No. 


Tin 

plate 


Pyrite 


Gypsum 


Lime 


Silicon 


Fe-Si 


Carbon 


S 


Sn 




scrap 


lb. 


lb. 


lb. 


lb. 


lb. 


lb. 


per 


per 






lb. 














cent 


cent 




9 


25 


0.25 








1 


3 


0.21 


0.80 


36 


10 


25 


0.50 




, 




1 


3 


0.43 


0.67 


46 


11 


50 


1.50 




3 


1.5 


2 


6 


0.09 


1.20 


4 


12 


50 




5.5 






2 


6 


0.06 


1.07 


14 


13* 


50 


2.66 








2 


2.5 


0.36 


0.95 


24 



* The metal in this test was treated with a desulfurizing slag before tapping. 

not complete in any test and became less rapid as the concentra- 
tion of the tin in the iron became less. The relatively small elim- 
ination obtained in Runs 11 and 12 was due to the basic slag 
which kept the sulfur from dissolving in the iron. As a result 
of these tests, it seems that although tin dissolved in molten 
iron may be converted to sulfide and volatilized, complete elimina- 
tion is i)robably impossible and the removal of even small amounts 
of tin by this means introduces a large amount of sulfur into the 
iron. These preliminary experiments were not sufficiently en- 
couraging to warrant further work along this line. 

In order to make the data more complete tests were made in 
which iron, coated with both tin and lead (terne plate), and 
galvanized scrap were melted with carbon. In the melt using 



DETIXXING OF TIN-PLATE SCRAP. I97 

scrap containing 1.9 per cent tin and 2.5 per cent lead, practically 
no elimination of the tin and complete elimination of the lead 
were obtained. Some of the lead was vaporized and the rest of 
it, on tapping, ran out of the furnace ahead of the molten iron 
in which it was insoluble. In the test using galvanized scrap con- 
taining 8.22 per cent zinc, the resultant metal contained only 0.20 
per cent zinc. Thus, unlike tin, lead and zinc are both readily 
removed from iron by melting in the electric furnace. 

Cupola Tests. 

In order to determine the degree of detinning possible in the 
cupola, the following experiments were conducted. 

Charges consisting of 25 lb. of tin-plate scrap, 75 lb. of gray 
iron and a large excess of coke were melted in a small cupola 
45.5 cm. (18 in.) in diameter. In one case, when a strong blast 
was used, the resultant metal contained only half of the tin 
charged. In another instance, in which a light blast was used, 
the temperature of the metal was consequently low and a viscous 
melt was obtained with practically no elimination of tin. A 
sample obtained from the castings made at a local sash-weight 
foundry by melting four parts gray iron and one part baled tin- 
plate scrap in a large cupola was analyzed and found to contain 
0.37 per cent tin. Assuming that the tin-plate scrap contained 
1.7 per cent tin (the average for all scrap detinned in 1921), a 
recovery of practically 100 per cent of the tin was obtained. 

One thousand pounds of synthetic cast iron was made in the 
electric furnace from tin-plate scrap and used as the iron in a 
regular cupola melt at a local foundry. The iron before melting 
in the cupola contained 1.25 per cent tin, and after melting 1.23 
per cent tin, thus showing practically no elimination. 

It is apparent from the above study that some elimination 
of tin, probably up to 50 per cent, may be effected by melting thin 
sheets in a strongly oxidizing atmosphere, that there is practically 
no loss of tin when melting large pieces of iron containing tin 
in solid solution, and that the tin removed in cupola melting is 
dependent upon the conditions of melting and the state in which 
the tin is present. 



198 C. E. WILLIAMS, C. E. SIMS AND C. A. NEWHALL. 

SYNTHETIC CAST IRON FROM TIN-PLATE SCRAP. 

Effects of Tin in Cast Iron. 

Believing it to be impractical to effect detinning in the electric 
furnace or the cupola, experiments were then conducted to deter- 
mine what effect tin had on cast iron, and whether suitable cast- 
ings could be made from synthetic cast iron made from tin-plate 
scrap. Test bars containing quantities of tin varying from 0.05 
per cent to 5.0 per cent were cast from pig iron melted with the 
required proportions of tin in an electric furnace. The tests on 
these bars showed that tin increases the hardness and decreases 
the transverse, compressive and tensile strengths, as well as the 
resistance to impact. Chemical analyses showed a decrease in 
graphitic carbon as the tin content increased, and microscopic 
examination gave evidence that less than 1 per cent of tin has no 
effect upon the size and shape of the graphite. These effects of 
tin are in direct proportion to the amount present, and roughly, 
1 per cent of tin will reduce the strength of gray iron 15 per 
cent. The effect on hardness and graphitic carbon will not be 
over 10 per cent. When the tin content is 2 per cent or more, 
the molten iron appears dirty, does not fill the mold well, and the 
castings are rough and porous. 

It seems, therefore, that tin-plate scrap or old tin cans can be 
used in the production of synthetic gray iron for the ordinary 
grade of castings provided the tin content of the product can be 
kept to 1 per cent or less. If the scrap contains more than 1 
per cent of tin it should be mixed with enough tin-free scrap to 
bring the average tin content to about this figure. 

Commercial Tests. 
In order to obtain more data on the value of tin-plate scrap 
as a raw material in the manufacture of synthetic cast iron, one 
thousand pounds of it were melted and carburized in a basic- 
lined, single-phase, roofed Heroult furnace. The composition of 
the product is shown in Table III. It was taken to a local foundry 
and used in one of the regular cupola melts. Both heavy sections 
and thin ornamental castings were made from it. All parts of 
the molds were well filled, and the castings without exception 
were smooth and sound. A machining test was made by the 



DETINNING OF TIN-PLATK SCRAP. 



199 



manager, who was well satisfied with the iron and gave the fol- 
lowing report: 

"Depth of chill, nil. Very soft. Cuts readily with hack saw. 
Drills easily with ordinary carbon drill. Turns readily in lathe 
at considerably over ordinary speed. On facing cut run at 36.6 
m. per min. (120 ft. per min.), 1.6 mm. (1/16 in.) depth of cut, 
0.79 mm. (1/32 in.) feed with Rex AA high speed steel. No 
difficulty to make deep cut with parting tool. Fracture very fine, 
dense, close grain, rather dark in color. Elasticity good." 

Five hundred pounds more of synthetic iron of the same com- 
position was made and submitted to another foundry for a similar 
test ; another favorable report was returned. 



Table III. 

Composition of Synthetic Iron Made from Tin-Plate Scrap before 
and after Melting in a Cupola. 





Before melting 
per cent 


After melting 
per cent 


c 


3.85 
1.34 
0.83 
e.45 
trace 
1.25 


3.78 
1.13 
0.60 
0.56 
trace 
123 


Si 


Mn 


P 


S 


Sn 





CONCLUSIONS. 

1. It is impossible to remove most of the tin in tin-plate scrap 
or similar material by any of the electric furnace melting pro- 
cesses tried; moreover, it is impractical to attempt any detinning 
by these means. 

2. No tin is volatilized, ordinarily, when iron scrap contain-ing 
it is melted in the electric furnace. 

3. The amount of tin volatilized during melting in the cupola 
may be as much as 50 per cent in some cases, whereas in others 
it may be practically nil, depending upon the amount of surface 
of metallic tin exposed, and the oxidizing condition of the blast. 

4. Lead can be removed completely from iron coated with lead, 



200 DISCUSSION. 

and likewise, zinc can be largely removed from galvanized scrap 
by melting in the electric furnace. 

5. A tin content of 1 per cent or less does not seriously affect 
the physical properties of cast iron. 

6. Under conditions prevailing in many parts of the country, 
tin-plate scrap and used tin cans can not be profitably treated 
bv any of the established detinning processes. This potential 
waste material can probably be recovered most usefully and 
efficiently by treating it in the electric furnace to produce syn- 
thetic cast iron, using low-grade, tin-free scrap for dilution to 
reduce the tin content of the product to within safe limits. 

ACKNOWLEDGMENTS. 

The authors are grateful for the helpful co-operation of the 
College of Mines, University of Washington, and also to Mr. 
Lyall Zickrick, graduate student in metallurg}'- at the University 
of Washington, for assistance with the physical examination of 
the cast iron test bars ; to Messrs. R. J. Anderson and G. M. 
Enos, of the Pittsburgh Station of the Bureau of Mines, for a 
microscopic study of the cast iron specimens containing tin, and 
to IMessrs. E. P. Barrett and J. D. Sullivan, of the Northwest 
Experiment Station of the Bureau of Mines, for the large amount 
of analytical work done in connection with this investigation. 



DISCUSSION. 



E. L. Crosby^ : There are several processes which look feasible 
from the electric furnace operating standpoint, affording possi- 
bilities of using sheet scrap, which do not work out so well in 
practice. The instant a plant starts in a certain community, where 
a cheap supply of scrap is available, the law of supply and demand 
operates. The cost of the material goes up, and it does not allow 
for any commercial margin. 

C. G. ScHLUEDERBERG- : I would like to have further light on 
just what the market is for some of this low-grade cast iron. Is 

> \'ice-Pres. and Gen. Mgr.. Detroit Elec. Furnace Co., Detroit, Mich. 
- Westinghouse Elec. and Mfg. Co., East Pittsburgh, Pa. 



DETINNING OF TIN-PLATE SCRAP. 20l 

there enough of a market to justify large operations in recovery 
of this material? 

H. W. GiLLETT" : On the economic end, may I ask whether this 
refers purely to selected scrap, clean scrap, or whether it is possible 
to pick up old tin cans and shove them into the furnace and use 
them ; in other words, whether somewhat oxidized scrap would be 
feasible for use or not ? When this proposition came up years 
agOj every community was to have a tin can wagon to collect 
them, and instead of having them go to the garbage man they 
were all to be picked up. I wonder if that point of view still 
olitains. 

C. E. Williams : In regard to Mr. Crosby's point regarding 
supply and demand, and that brought up by Dr. Gillett, we are 
looking to the future in this case just as much perhaps as any 
question in which we are involved. 

Much of the tin-plate scrap is treated by the chlorine detinning 
process, which produces tin tetrachloride used in weighting silk. 
We are not sure but that a cheaper or better substitute for tin 
tetrachloride will be developed. Such a development would liber- 
ate a large quantity of scrap. IMoreover, there are times when 
the spread between the cost of tin-plate scrap and of detinned 
scrap is not sufficiently large to make detinning by present meth- 
ods profitable. 

Large cities are developing efficient methods of garbage collec- 
tion and disposal, in which large picking bands are operated, old 
tinned containers being segregated and baled at a low cost. This 
practice will furnish a large potential supply of cheap scrap iron 
for use in producing foundry iron by the method described in this 
paper. A foundry in Los Angeles is now operating on a fairly 
large scale using baled cans collected in this manner and produces 
white cast iron therefrom. This company recently put into opera- 
tion an electric furnace for producing gray iron, but I do not 
know what success they have had. 

H. W. Gillett : Have you ever tried to use your tin-plate scrap 
as part of the iron base for semi-steel ? If your gray iron is not 
up to the mark on account of the presence of tin, for most uses 

3 U. S. Bureau of Mines, Ithaca, X. Y. 

14 



202- DISCUSSION. 

yon can improve the quality by going down on the carbon and 
making semi-steel out of it. 

C. E. Williams : We have not investigated the properties of 
semi-steel containing tin. However, it would probably be all 
right unless the physical properties of that semi-steel are affected 
more than the properties of gray iron are affected by tin. 

W^e know that tin has a decided action upon steel when present 
in very small quantities, and that it does not have much eft"ect on 
gray iron even when it is present in fairly large quantities. So 
as you go from gray iron down to steel, the deleterious effect of 
tin would probably increase. Hence it might be that semi-steel 
containing a few tenths per cent of tin would be affected to a 
greater extent than is gray iron. However, this is something that 
should be investigated. 



A paper presented as an introduction to 
the session devoted to the reading and 
discussion of papers on "Rarer Metals," 
at the Forty-third General Meeting of 
the American Electrochemical Society, 
held in New York City, May 5, 1923, 
Dr. F. M. Becket in the Chair. 



PRESENT STATUS OF THE PRODUCTION OF RARER METALS.' 

By C. James^ 

Many years ago, while attending a lecture in London Univer- 
sity, I heard of the work of Waldron Shapleigh, of the Welsbach 
Company. The lecturer described some of the work that was 
done in the days before the modern thorium mantle was evolved. 
Shapleigh had separated large amounts of lanthanum, praseody- 
mium, etc., in very pure form. The enthusiastic description of 
the beautiful salts, the mystery which enshrouded them, and the 
immense opportunities for research among the rare metals con- 
verted me completely. 

Although this section of chemistry has appealed to many, be- 
cause of the thought that there must be something unique about 
these substances, yet most of the work in the past has been 
devoted to their chemical characteristics. Notwithstanding the 
fact that much time has been spent searching for methods for 
detecting and for the quantitative determination of these elements, 
we find that in many cases good methods are completely lacking. 
The separation of tantalum and columbium is such an one. Even 
the determination of the mixed oxides requires great care, since 
these substances tend to retain both alkalies and acids. The acid 
solutions used during the work are liable to carry away some of 
the metallic acids. The errors act in opposite directions, the first 
tending to increase, and the latter to decrease the per cent. In 
working with these two elements along these lines, some of us 
have passed through discouragingly gloomy periods. However, 
many experiments along qualitative lines indicate that, after all, 
there appears to be quite a difference between these elements as 
regards their chemical properties. 

* Introductory paper to the session on "Rarer Metals." 

^ Professor of inorganic chemistry, New Hampshire College, Durham, N. H. 

203 



204 C. JAMES. 

Cupferron is a reagent that can be used for precipitating tan- 
talum and columbium together from acid solution. The oxalic 
acid solution, strongly acidified with sulfuric acid, or the hydro- 
fluoric acid solution containing considerable sulfuric acid, is readily 
precipitated by cupferron. The precipitation should be carried 
out in very cold solutions. The precipitate can be readily washed 
and the oxides, obtained by igniting this precipitate, appear to be 
very pure. The results seem to be exact. 

When solutions of pure tantalum and pure columbium, under 
the same conditions, are treated with cupferron, a great differ- 
ence is observed in the behavior of the precipitate. Tantalum 
gives no trouble in filtering and washing, while columbium is 
thrown down as a sticky semi-liquid mass. It will probably take 
some time before the conditions for an exact separation of tan- 
talum from columbium can be achieved. 

Recently some interesting observations have been made with 
regard to the effect of solutions of organic substances, such as 
bases, benzidine, quinoline, hexamythelene tetramine, piperazine 
hydrate, quinine, etc., upon solutions of tantalum and columbium 
dissolved either in oxalic acid solution or in a solution of methyl- 
amine or some similar substance. Qualitative experiments have 
shown that tantalum is usually more readily precipitated than 
columbium. However, there are cases where columbium solutions 
have been precipitated while those of tantalum have remained 
clear. The oxide of tantalum obtained by some of these tests is 
extremely white. 

So far as quantitative analysis is concerned, the greatest prob- 
lem is found in the case of the cerium and yttrium groups of 
metals. The separation of the two groups is an extremely tedious 
matter, which is rarely carried out. The precipitation performed 
with sodium or potassium sulfates is far from accurate. The 
precipitated cerium group may be as much as fifty per cent too 
high, while only a small fraction of the yttrium group may be 
separated as such. 

The most accurate method for sejiarating these elements is to 
stir the sulfate solutions with potassium sulfate until the solution 
no longer shows any neodymium absorption. The precipitated 
double sulfates are filtered oflf and washed with a solution of 



STATUS OF THE PRODUCTION OF RARER METALS. 205 

potassium sulfate. The filtrate is precipitated with oxalic acid. 
The oxalates are filtered off, washed, dried, ignited, the resulting 
oxides boiled out with water, filtered and washed with hot water. 
These oxides are dissolved in the least amount of hydrochloric 
acid, the solution boiled and precipitated again with oxalic acid. 
These oxalates upon ignition give a portion of the yttrium oxides. 
The other portion is separated from the precipitated double sul- 
fates by converting to hydroxides or oxides. These are then 
dissolved in nitric acid. A similar amount of nitric acid is then 
neutralized by magnesium oxide and the solution added to the 
rare earth nitrates. The liquid is then evaporated to crystalliza- 
tion. The mother liquor is poured off, a quantity of bismuth 
magnesium nitrate added, together with some concentrated nitric 
acid. The mass is heated and allowed to crystallize. The original 
crystals are also recrystallized. A short fractional crystallization 
is carried out. All mother liquors that fail to show neodymium 
or samarium absorption bands are placed aside. When no more 
mother liquors of this type can be obtained, the process is stopped. 
The mother liquors are then diluted, the bismuth removed by 
hydrogen sulfide, and the yttrium earths precipitated by oxalic 
acid. This precipitate is filtered off, washed and ignited. This 
oxide, together with that obtained from the potassium sulfate 
solution represents the total yttrium earths originally present. 
The yttrium earths at the gadolinium end give double sulfates 
that are almost insoluble in potassium sulfate solution. 

Some metals may have been neglected either because they were 
considered to be absolutely useless, or because they appeared to 
be too rare. When an element is condemned as being useless, 
it is evident that its characteristic properties are deeply hidden. 
Many years ago, thorium oxide was a very rare substance, and, 
one would suppose, considered useless. When it was found to 
be an ideal substance for the Welsbach mantle, a search was made 
for new mineral locations. At first the occurrence seemed to be 
very limited, and the production of a cheap mantle seemed to be 
out of the question. Finally the search for new raw material 
was rewarded by the discovery of monazite sand. Today large 
amounts of sand are obtained from Brazil and Travancore. Many 
other deposits are known, but most of them possess a lower 



206 C. JAMES. 

thorium content than those mentioned. At the present time there 
is enough thorium for mantles and for other purposes, if such 
can be found. 

If we search the Uterature for work on germanium, we shall 
find little, apart from that at the time of its discovery, and that 
done during the last two or three years. This substance, which 
once seemed so useless, is attracting much attention in the medical 
world, because of its action on the blood. According to several 
authorities, it should be of great value in certain cases of anaemia. 
This element occurs in argyrodite and canfieldite (which appear 
to be very rare), and to a very minute extent in some zinc ores. 
That occurring in the zinc ores is concentrated in the regenerated 
zinc oxide, which is obtained from the retort residues. Even 
after concentration, the amount of germanium dioxide is still 
very small. 

Recently it has been stated to occur in a copper ore in Africa. 
Some of this mineral, which is said to occur in considerable 
quantity, was obtained and examined. The mineral proved to be 
rich in germanium, which is easily extracted in an exceedingly 
pure condition. There is therefore a possibility that this metal 
may become sufficiently plentiful so that its effect upon metals 
and alloys may be determined. It alloys quite readily with cop- 
per; 5 per cent gives a pale gold colored alloy. 

G. Urbain informed me, at the New Haven meeting last April, 
that he treated several tons of zinc ore and obtained only a few 
grams of germanium dioxide. This was finally loaned to a 
doctor, who returned two decigrams. Germany, I understand, 
has forbidden the export of germanium and its compounds. 

Will thulium ever be of any use ? It must be admitted that it 
is very rare and extremely troublesome to separate. The oxide 
certainly possesses characteristic properties, for it glows when 
heated. With careful heating it gives a beautiful carmine colored 
light, which changes as the temperature is raised, becoming yellow 
and then almost white. I am optimistic enough to believe that 
all these very rare elements will prove to be of great importance 
in the future. Much work may have to be done, and we must 
not be discouraged by stone age talk in the time of super-steel. 

On the other hand there are some of the so-called rare elements 



STATUS OF THE PRODUCTION OF RARER METALS. 207 

occurring fairly commonly in nature which have been subjected 
to considerable research, and which, unfortunately, are still un- 
conquered. ^Metallic beryllium is a good illustration of this group. 

Beryl, 3BeO . Al^O. . 6SiOo, occurs in the United States in 
New Hampshire, etc., and in many other parts of the world. It 
would seem that in the case of this element there are perhaps 
three reasons why the metal is not well known. The mineral, 
beryl, is not readily decomposed ; the separation of beryllium from 
aluminum is not an easy matter, and the reduction of beryllium 
compounds presents great difficulties. 

Perhaps the simplest way to decompose beryl is to heat with 
sodium hydroxide in the following manner: The mineral ground 
to 200 mesh is mixed with 1.5 parts of sodium hydroxide, and 
heated over a powerful oil burner. The mass first softens, then 
fuses and boils, after which it dries to a friable, bluish earthy 
mass. During the drying, the whole should be well stirred so 
as to yield a line powdery product. Care should be taken to 
prevent a second fusion in which a glass would result. Under 
good conditions nearly complete decomposition of the beryl is 
obtained (98 per cent). This friable product is found to be 
superior to the glassy mass obtained by a second fusion, since 
it is easily leached by water. Careful extraction by water removes 
about 30 per cent of the total silica, and a considerable amount of 
sodium hydroxide. The amount of ber^dlium found in solution 
is negligible. This leaching is best carried out by grinding with 
water in a ball mill. It is considered advisable to make this ex- 
traction in order to save mineral acid in the next stage of the 
process where the alkali is removed by treatment with acid. 

The powdered product of the fusion, or the residue from the 
leaching is stirred with water, sulfuric acid being added from 
time to time to neutralize the alkali. It is essential that the liquid 
be neutral or slightly alkaline towards the end of the stirring, the 
desired result being the removal of the soda, leaving the beryllium, 
aluminum and silica in the residue. The mass is then filtered, 
washed and treated with dilute sulfuric acid to extract the beryl- 
lium and aluminum. The solution is filtered off, evaporated to 
dryness and gently heated to render the silica insoluble. The 



2o8 C. JAMES. 

residue is taken up with water, and the resulting solution contains 
the beryllium and aluminum originally present in the ore. 

A solution of the sulfates is tested for the amount of mixed 
AI2O3 + BeO. Assuming that the oxides exist in solution in 
the same ratio as they occur in beryl, about three times as much 
ammonium sulfate is added as is required by theory to convert 
the aluminum sulfate to ammonia alum, 

Al^CSOJs . (NHJ3SO, . 24U,0. 

The solution is concentrated and cooled to 10° C, when, if the 
concentration has been sufficient, practically the whole of the 
aluminum separates out in the form of alum. The liquid upon 
examination is found to be almost entirely free from aluminum. 

A small amount of iron still remains, and this is separated by 
diluting the solution, heating to boiling, and oxidizing the iron 
if necessary by potassium bromate or some other suitable oxidiz- 
ing agent. The liquid is then neutralized by ammonium hydrox- 
ide, and the iron precipitated by ammonium acetate and a slight 
amount of acetic acid. If too much acetic acid is liberated, more 
ammonium hydroxide is added to neutralize the great excess. 
When a sample upon filtering and treating with ammonium sulfide 
gives a white precipitate, it is concluded that all iron has been 
removed. The whole is then filtered, the filtrate boiled and the 
beryllium precipitated as basic carbonate by means of ammonium 
carbonate or sodium bicarbonate. The basic carbonate is filtered 
off, washed with boiling water and gently dried. 

This method, when carefully carried out, gives a product which 
is almost chemically pure. The regaining of the ammonium 
sulfate is an important matter, which has not been completed at 
present. Many thanks are due to H. C. Fogg, J. F. CuUinan and 
D. A. Newman for carrying out this work. 

The reduction of beryllium compounds such as the oxide by 
calcium and magnesium, the chloride by sodium and calcium ; 
and the electrolysis of fused salts and salt solutions is still under 
investigation. Before we can make much more progress with 
regard to beryllium, it is essential that we know more about its 
constants, and that we have a simple method for its quantitative 



STATUS OF THE PRODUCTION OF RARER METALS. 209 

determination. Such knowledge would allow us to study solu- 
bility curves and alloys with rapidity. 

A few years ago the difficulties of a zirconium determination 
were as great as those of beryllium are now. However, as zir- 
conium grew in commercial value, so the accuracy of its deter- 
mination improved. 

During recent years new reagents have been recommended from 
both inorganic and organic divisions. The organic section seems 
to be rich in reagents which may be applied to the titanium, 
zirconium, cerium, thorium" family. Phenylarsonic acid is one 
which is being thoroughly examined at the present time. The 
substituted phenylarsonic acids act similarly. This substance 
precipitates zirconium and titanium from solutions very acid 
with hydrochloric acid, while cerium and thorivmi remain in solu- 
tion. There seems to be considerable difficulty in driving off all 
the arsenic on ignition. Igniting in a current of hydrogen rapidly 
removes all arsenic. 

Phenylarsonic acid precipitates thorium from solutions con- 
taining ten per cent acetic acid and a slight excess of ammonium 
acetate. Under the same conditions the metals of the cerium and 
yttrium groups are not precipitated. Cerium must be in the 
cerous state. However, the thorium carries down a small amount 
of the rare earths, and it is necessary to make a second precipita- 
tion. This is easily performed by dissolving the thorium phenyl- 
arsonate in a little hydrochloric acid, diluting and adding acetic 
acid until the solution contains about ten per cent. The thorium 
is then reprecipitated by adding an excess of ammonium acetate, 
and a little more phenylarsonic acid. This second precipitate 
is once again dissolved in hydrochloric acid, the solution diluted, 
and the thorium thrown down as oxalate. The oxalate is filtered 
off, washed, dried and ignited to oxide. Thorium phenylarsonate 
can be ignited directly to oxide, if a current of hydrogen be used 
to reduce any arsenic remaining after the first ignition. 

When hydrogen peroxide is added to a solution of cerium 
nitrate containing a little acetic acid, an excess of ammonium 
acetate and phenylarsonic acid, a precipitate of the eerie com- 
pound rapidly forms. The quantitative nature of this reaction 
has not been ascertained as yet. 
15 



2IO C. JAMES. 

Phenylarsonic acid can be easily prepared according to the 
method recommended by Roger Adams (Journal American 
Chemical Society, 1922). 

We must not forget that long list of elements known as the 
rare earths, which includes the members of the cerium and yttrium 
groups. It seems unfortunate that these substances, which are 
obtained in considerable quantities as a by-product during the 
extraction of thorium, have not found many uses commercially. 
It is true that some are used to a certain extent, however a large 
amount goes to waste. If we except cerium, the chemistry of the 
remaining elements is a little section all by itself. These rare 
earth elements resemble a homologous series of carbon compounds 
in many respects. Many properties when plotted against the 
atomic weights give interesting curves. If the solubilities of 
a set of isomorphous compounds, containing the same amount of 
water of crystallization are examined, it is usual to find that they 
lie upon a smooth curve. On the other hand a set of compounds 
possessing two or three states of hydration will give a curve 
resembling that of a single substance at various temperatures 
where two or three states of hydration are met. 

Unfortunately, in this family the separation of the elements 
from each other is no simple matter. With few exceptions, quan- 
titative analysis is unknown. The exceptions include cerium and 
those members which lie at opposite ends of the series. Cerium 
can be separated by converting it into the eerie condition, when 
its properties become similar to those of thorium. 

Lanthanum, which occurs at one end, can be separated from 
erbium, which occurs near the opposite end of the series, by stir- 
ring the solution of the nitrates with magnesium nitrate and an 
excess of bismuth magnesium nitrate. Lanthanum magnesium 
nitrate is precipitated out, being insoluble in the bismuth mag- 
nesium nitrate solution. Erbium remains in solution in the form 
of the simple nitrate. 

There is therefore little trouble in separating two elements that 
lie far apart in the series. It is an easy matter also to separate 
one element, such as lanthanum, from several elements occurring 
at the opposite end by the above method. The greatest difficulties 
are encountered when an attempt is made to separate two or three 



STATUS OF THE PRODUCTION OF RARER METALS. 211 

consecutive elements such as lanthanum, praseodymium and neo- 
dymium. In this case the praseodymium comes between the lan- 
thanum and neodymium when the double ammonium nitrates are 
fractionated. Lanthanum ammonium nitrate is the least soluble, 
while the neodymium salt is the most soluble. Praseodymium 
ammonium nitrate tends to accompany both. 

The three elements presenting the greatest difficulty are dys- 
prosium, holmium and yttrium. In certain cases, the scarcity of 
an element makes the problem still more difficult. This is recog- 
nized in the cases of europium, terbium and thulium. 

Many members of the rare earth group can be obtained in large 
amounts and at a reasonable cost whenever required. This state- 
ment applies especially to cerium, lanthanum, praseodymium, neo- 
dymium and yttrium. Of course it is evident, when a use is found 
for the elements mentioned, that those which are rarer will be 
more easily obtained. 

Although we often come across the statement that the rare 
earths are no longer rare, we must realize that this is not general. 
In fact europium, terbium, thulium and celtium are exceedingly 
rare. Some zinc ores contain more gallium than monazite sand 
contains europium. 

Since the separation of these elements is based upon slight 
differences, the process has to be repeated many times. In some 
cases thousands of operations have to be carried out before some 
of the desired salt can be obtained pure. Fractional crystallization 
or fractional precipitation can be employed. The former is 
usually selected because it is cheaper and more efficient in the 
long run with large amovmts. Perhaps the cases of lanthanum 
and yttrium are exceptional, for in these cases precipitation plays 
a big part. 

With regard to fractional crystallization there are two special 
lines which are being examined at the present time: (a) Solu- 
bility curves of various salts in various solvents; and (b) the 
effect of one rare earth salt upon another. In addition to this 
large amounts of dysprosium, holmium, erbium, thulium, ytter- 
bium and lutecium are being separated in order to prove whether 
there are any other elements occurring in minute amounts in this 
series. Welsbach believes that some of these elements, such as 



212 C. JAMES. 

terbium, thulium, etc., are complex. This is rather against the 
theory of Urbain. and the problem should be settled. It is evident 
therefore, that the rare earths require considerable investigation, 
for as yet we know little about them. Only a few of the metals 
have been obtained in a fused state. We have learned much with 
regard to the structure of atoms from the radio-active elements, 
and it is highly probable that the rare earths will give us a whole 
lot more. 

Rare earth research is slow and tedious, but it is simple com- 
pared with what it used to be. That which required years in the 
time of Crookes can be done now in about as many weeks. 

Gallium and indium, two other elements of group III, should 
be mentioned. If only gallium could be obtained in quantity, it 
would without doubt find many uses, for it has a low melting 
point, and when pure has many properties approaching those of 
the noble metals. A few years ago, after the discovery made by 
the Bartlesville Zinc Company, it looked as though there would 
be enough material to supply all those who desired to work upon 
it. However, the ore containing gallium occurs only in pockets. 
Upon purifying this crude zinc by redistillation, a leady residue 
was obtained, which was rich in gallium and indium. Unfortun^ 
ately, this process has been discontinued. 

Indium occurs much more commonly in certain zinc by-pro- 
ducts. Some flue dusts have shown about 0.5 per cent of this 
element. All this material passes through the smelters and the 
indium is lost. 

\\'hen we study a list of rare metals, we note that many ele- 
ments, such as titanium, zirconium, etc., are commoner than many 
of the metals with which we come in contact every day. These 
elements form stable compounds that are reduced with difficulty. 
Moreover, the metals when finely divided are very active, com- 
bining with oxygen, nitrogen, carbon, silicon, etc. This great 
activity and a melting point beyond the range of most furnaces 
easily account for the stupendous work required for solving 
such matters. 

It is not long since we had to use the greatest of care in hand- 
ling tungsten lamps. It would be a nightmare to a man accus- 
tomed to the use of ductile tungsten, to be placed in a lamp 



STATUS OF THE PRODUCTION OF RARER METALS. 213 

factor^' under the old conditions. Some of us doubtless remember 
those old times with the huge amount of labor involved. The 
production of ductile tungsten at one time seemed remote, al- 
though the number of investigators was comparatively great. 
Finally this difficult matter was solved, and not until then did the 
tungsten lamp really become commercial. Today tungsten and 
molybdenum can be worked as may be desired. 

Tantalum, which was originally worked by Siemens-Halske, is 
now being produced by the Fansteel Company in a ductile form. 
They also state that columbium can be put on the market in a 
similar state. 

It is especially interesting to observe that with improved meth- 
ods, both zirconium and uranium metals give melting points very 
different from the figures obtained by earlier workers. The prob- 
lem is being attacked in the correct manner at the present time. 
The first aim is to obtain pure metal, regardless of the cost 
of the process, in order to study its properties. When these have 
been outlined, it will be much easier to reason out a simpler plan. 

Zirconium is an element occurring generously in nature, so its 
commercial possibilities are considerable. One of the great costs 
is the purification of the salts and oxide. The cost of production 
is, however, much less than it used to be. The indexes of the 
various journals are a good gauge of the attention that the various 
elements are receiving. If the number of patents mean anything, 
the future of zirconium should be assured. 

Uranium, a by-product obtained during the extraction of 
radium salts, is easily purified. The new deposits of the Congo 
indicate that there will be no shortage of this element in the near 
future. Probably long before this new region is exhausted, others 
will be discovered. Since uranium is a member of the tungsten, 
molybdenum and chromium family, it ought to have commercial 
value. 

The rare elements will also have many uses when in the form 
of compounds. Probably some will be used as catalysts. Thal- 
lous chloride acts as an excellent chlorine carrier, especially in 
the chlorination of hydrocarbons. Benzyl chloride is not pro- 
duced when toluene is used. Zirconium has a tendency to remove 
hydrogen from compounds. 



214 ^- JA^^ES. 

Many of the rare metals are thoroughly established in the com- 
mercial field, but we must realize that some are completely dis- 
carded. If the minerals are not being used, of course it does 
not matter much, for they can be mined when wanted. It is 
sad, however, when many rare metals, obtained as by-products, 
have to be thrown away. 

As time goes on the remaining territory of the rare metals 
will become more and more difficult to explore, since the easier 
ones fall before the steadily increasing power of the investigators. 
It is highly probable that in all difficult tasks, the worker, at 
times, is liable to become discouraged. However, we have 
many fine illustrations in the past where the problems seemed 
hopeless, but where the work was finally crowned with success. 
It is especially interesting to read the work of Crookes upon his 
search for certain elements giving phosphorescent spectra. 

We who are interested in the commercial application of the 
rare metals, ought to be thankful that we are working at this 
period, for these substances are being launched upon their journey 
through the commercial world as never before. It is our duty 
to assist in this project. What greater reward can we have than 
to learn that they have proved seaworthy, and are steadily going 
ahead. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 5. 192S, Dr. F. M. Becket in 
the Chair. 



THE PREPARATION OF FUSED ZIRCONIUM/ 

By Hugh S. Cooper.- 
INTRODUCTION. 

In the course of certain alloy investigations a considerable 
quantity of zirconium was needed to pursue the work. This 
metal is a rather scarce commodity, and therefore its preparation 
in the laboratory became necessary. Although nothing novel 
is claimed for the process described herein, yet there are a number 
of interesting features and essential precautions involved in the 
production of the metal, which are considered of sufficient im- 
portance to be published in some detail. The experimental data 
on the establishment of the melting point of zirconium metal 
are also given, as well as a brief description of some new alloys. 

After due consideration of the various methods employed in 
the past for making zirconium, it was decided to adopt the 
method in which zirconium tetrachloride is reduced by sodium, 
because this seemed to be the most promising. Previous ex- 
perience in producing anhydrous chlorides also influenced this 
decision to some extent. Although some zirconium chloride was 
made by passing chlorine over the oxide in the presence of car- 
bon, the yields were rather unsatisfactory. By far the major 
portion of the work was carried out by the action of chlorine upon 
zirconium carbide, a procedure which gave satisfactory results. 

The carbide chlorination scheme has been used heretofore by 
Moissan and Lengfeld,^ and also by Wedekind,* but a brief des- 
cription of the apparatus used in the laboratory, as well as the 
results obtained, will be given because of some rather important 
considerations involving the purity and physical character of the 

^ Manuscript received February 14, 1923. 

= Kemet Laboratories Co., Inc., Cleveland, O. 

3 Moissan and Lengfield. Compt. Rend. 122. 651 (1896). 

* Wedekind, Preparation of Zirconia and Tetrachloride Z. anorg. Chem. 33, 81. 

215 



2l6 HUGH S. COOPER. 

chloride, the latter greatly influencing the yield of zirconium 
metal during reduction. 

PREPARATION OF ZIRCONIUM TETRACHLORIDE. 

The furnace, as shown in the accompanying illustration, Fig. 
1, is of the horizontal, wire-bound tube t}"pe in which temperatures 
up to 1000° C. are obtainable. The carbide is placed in silica 
or alundum boats approximately 7.6 x 15 x 2.5 cm. (3 x 6 x 1 in.) 
deep. These boats hold approximately 228 g. (8 oz.) of material 
each and are inserted in a fused silica tube which fits snugly into 



Fig. 1. 

Clilorination Furnace. 

the furnace. The diameter of this vitreosil tube is about 7 .6 cm. 
(3 in.) and the length about 92 cm. (3 ft.) One end of the 
tube is fitted into a terra cotta condenser by means of a thick 
rubber stopper. The other end of the condenser is also sealed 
with a rubber stopper ol equal size, in the center of which is an 
opening for the chlorine outlet tube. This condenser is approxi- 
mately 30 cm. (12 in.) in diameter by 46 cm. (18 in.) long. 

After placing the carbide in the boats the tube is sealed and 
the current applied until a temperature of 500° C. is indicated 
by a thermo-electric pyrometer, the couple being adjacent to 
the outside wall of the silica tube. At this time a stream of 
chlorine is allowed to pass over the carbide, the temperature 



THE PREPARATION OF FUSED ZIRCONIUM. 2I7 

being held as close to 500 or 550° C. as possible, since this seems 
to be the optimum temperature from the standpoint of selective 
separation of the iron. The physical condition of the chlorine 
depends upon the temperature at which it is condensed, and 
this determines to a great extent the yield of zirconium metal 
which is obtained upon reduction. For example, that chloride 
which has been condensed in the terra cotta pipe is in a fine state 
of sub-division, due probably to the rapid cooling at normal tem- 
perature, whereas, that in the end of the silica tube near the 
entrance to the condenser consists of a heavy dense mass of 
large crystals. The temperature at this point is about 200° C. 
as a maximum. As soon as the carbide has been converted to 
chloride, which usually takes four or five hours, the respective 
chlorides above mentioned are removed separately and placed 
in glass stoppered bottles. The voluminous finely divided ma- 
terial is very hygroscopic, rapidly absorbs moisture, and in so 
doing assumes a lemon-yellow color characteristic of the oxy- 
chloride. The heavy crystalline material, on the other hand 
is much less affected by moisture and can be transferred many 
times with slight absorption of water. 

NATURE OF CARBIDE. 

An analysis of some of the carbide used in some of these 
experiments is given below : 

No. 1 No. 2 

Zr 73.88 83.78 

Fe 0.63 1.00 

Ti 0.41 0.48 

Si 0.10 1.40 

C 23.50 12.96 

98.52 99.62 

Many experiments have conclusively demonstrated that car- 
bide containing some free graphite, similar in analysis to No. 1, 
is more readily attacked by chlorine and at much lower tempera- 
tures than material of the second type which more nearly ap- 
proaches ZrC in composition. As a matter of fact, ZrC shows 
only a superficial attack at temperatures of 800° C. and is a 
very dense, heavy material. The former is of a light porous 



2l8 HUGH S. COOPER. 

nature, is friable and gives practically the theoretical recovery of 
the metal as chloride. 

A representative analysis of zirconium oxide made from chlor- 
ide, by exposing the same to the action of steam with subsequent 
ignition, follows: 

Per Cent 

Zr O, 99.44 

Ti O2 0.12 

Fe^O. 0.28 

Si O5 0.08 

99.92 
REDUCTION OF ZIRCONIUM CHLORIDE. 

The furnace depicted in Fig. 2 is 55 cm. (21.5 in.) in height 
and has an outside diameter of 15 cm. (6 in.) It consists of two 
parts, the upper containing the periscope for observing the tem- 
perature of the reaction and a tube connecting with the vacuum 
pump. The lower part of the furnace consists essentially of a 
cylindrical tube having an inside diameter of 13 cm. (5 in.) and 
13 mm. (0.5 in.) wall, to which a base is welded, the upper part 
having a 13 cm. (5 in.) opening with a welded steel collar. The 
height of the cylinder is 33 cm. (13 in.) and the collar is 41 mm. 
(1 5/8 in.) in diameter. Just below this collar is a threaded plug 
in which the terminals are placed which conduct the current to 
the inside of the cylinder. A lead gasket is used between the 
top and base to make an absolutely air-tight joint. 

The heating unit consists of an alundum core wound with 
nichrome and is 5 cm. (2 1/8 in.) inside diameter by 23 cm. 
(9 in.) long. Between the outside wall of this core and the 
steel shell the space is insulated with sand. The steel cylinders 
in which the zirconium chloride and sodium are packed are 21 
cm. (8 1/4 in.) long by 45 mm. (1 3/4 in.) in diameter, and are 
provided with screw tops. Dense crystalline zirconium chloride 
only is employed to make the metal, since it is more permanent 
in air and permits a greater weight of material to be used per 
charge, due to the smaller volume. The amount of chloride and 
sodium used for each reaction is based upon the equation : 

ZrCl, -f 2Nao -> 4NaCl -f Zr 

The theoretical amounts would therefore be 232 g. of chloride 



THE PREPARATION OF FUSED ZIRCONIUM. 



219 



plus 92 g. of sodium, this yielding about 90 g. of metal. In actual 
practice 230 g. of chloride and 92. g. of sodium are used, as the 
slight excess of sodium can be easily washed out and a complete 
reduction of the chloride is thus assured. 

Zirconium chloride and sodium in the proportions given above 
are rapidly placed in alternate layers in the iron cylinder, the cap 




riG. _'. 
Reduction Furnace. 



is tightly screwed on, and the cylinder inserted in the furnace. 
The furnace top is then bolted tightly on and the cylinder is then 
exhausted. At this stage the current is applied and within a 
short time a temperature of 500° to 600° C. will have been reached. 
Close observation at this point will show a sudden rise in tem- 
perature, the cylinder reaching about 900° to 1000° C. It is 
held at this temperature for a short time, current is turned off, 
when the cylinder has become cold the pump is cut oft and the 



220 HUGH S. COOPER. 

furnace opened. It is extremely important not to remove the 
cap from the cylinder until the temperature has dropped to 
normal because of the extreme activity of the metal, which ignites 
upon the slightest friction. When the cylinder has been opened 
a black skeleton-like mass is exposed to view. This is slowly 
added in successive portions to a large volume of cold water. It 
will be immediately found that the heavy lamellar material sinks 
to the bottom while the powder remains suspended, and in this 
manner an easy separation is effected. The metal is thoroughly 
washed with cold, and finally hot, water until entirely free from 
sodium salts ; it is next dried for several days at a temperature 
not exceeding 85° C. If this procedure is carefully followed, 
metal having the following approximate analysis will be obtained-. 

Per Cent 

Zr 99.28 

Fe 0.14 

Ti 0.13 

Si 0.07 

99.62 

The metal suffers little loss either in concentrated or in dilute 
hydrochloric or nitric acid, even when boiled therein. It is also 
practically insoluble in dilute sulfuric acid, but dissolves com- 
pletely in boiling concentrated sulfuric, 

EXPERIMENTS TO DETERMINE THE MELTING POINT OF 
ZIRCONIUM METAL. 

The melting point of zirconium is not known with certainly 
even at this late day. According to Von Bolton this point lies in 
the neighborhood of about 2350° C. Burgess states that three ex- 
periments gave 1529°, 1533°, 1523°, and he decided on 1530° C. 
as the melting point. According to Guertler the melting point 
is around 1700° C. Having a considerable amount of metal on 
hand, with ample equipment at our disposal, it was decided to 
make a few experiments in an attempt to correct these dis- 
crepancies. The melting experiments were carried out in argon 
and hydrogen, as well as in vacuo. Two types of furnaces were 
used. One of these was an Arsem furnace, in which the metal 
was melted in especially prepared zirconium oxide crucibles, the 



THE PREPARATION OF FUSED ZIRCONIUM. 221 

Other of a type used in treating tungsten and molybdenum rods, 
one end of the metal being clamped to the upper electrode, the 
other dipping into a pool of mercury which acts as the lower 
electrode. 

The zirconium metal, in large pieces which have been carefully 
dried for several days at the prescribed temperature, is weighed 
in lots of 35 grams each. These lots, placed successively in a 
die and subjected to a pressure of about 35 tons, yield rods 
about 6 mm. (1/4 in.) square and 25 cm. (10 in.) long. The 
heating of these rods in the tungsten treating furnace in an at- 
mosphere of argon or hydrogen, has been only partially success- 
ful up to this time, and the experiments are being continued. 
Traces of ox\-gen still remaining in argon, as well as moisture in 
both gases, has prevented obtaining full-length bars of completely 
sintered zirconium having a clean surface similar in appearance 
to that of tungsten or molybdenum. Nearly all such rods showed 
superficial oxidation, although in some instances short lengths 
of well-fused metal have been obtained. These experiments indi- 
cate that if practically dry hydrogen were employed it should 
be possible to make solid bars of metal by this method, and it 
is also believed that once the metal reaches a fused state the 
hydride will not be formed at the lower temperatures upon 
cooling. 

The melting experiments in the Arsem furnace, utilizing zir- 
conium oxide crucibles, gave some gratifying results. The tem- 
perature measurements were made with a Leeds & Xorthrup 
optical pyrometer, especially calibrated for temperatures up to 
3000° C. The curve supplied with the furnace, in which the 
temperature is plotted against the power input, enabled us to 
check the temperature readings closely. An accurate check was 
also obtained by use of molybdenum and tantalum, which have 
well-defined melting points. 

In the first experiment a rod of pure molybdenum metal was 
placed on one end of a zirconia slab, and on the other end a rod 
of pressed zirconium metal. Previous tests in alundum crucibles 
had shown that the melting point of the metal was above that 
of alundum. The first optical reading was taken at 2420^ with 
8.5 kw. input, which gave 2475° on the chart. A final reading 



222 HUGH S. COOPER. 

was taken at 9.5 kw., corresponding to 2600°, and at this tem- 
perature one end of the molybdenum rod had melted to a small 
button. The optical reading at this time gave a temperature of 
2630° C. Upon removal from the furnace the metal rod was 
observed to possess a well-sintered appearance, but it was not 
fused. 

In the next experiment several grams of metal were placed in 
a zirconium oxide crucible. The temperature reached 2650°, 
with a power input of 11 to 11.5 kw. The zirconium in this in- 
stance was well-sintered, but showed no signs of fusing and 
no loss in weight. 

In the third trial the metal was placed on one end of a zir- 
conium oxide slab, with a piece of pure tantalum on the opposite 
end. At 2800° the zirconium had partially fused into small, 
flat sections without showing a complete melting, the tantalum 
had begun to "sweat," indicating a temperature close to the 
melting point. This was checked with a further and similar 
experiment. The temperature in this experiment reached 2865° 
C. The tantalum showed distinct fusion on one corner, and 
the zirconium had flowed rather freely over the sides of the 
slab. This was checked closely in a further test in which no 
tantalum was used. In the sixth test several grams of metal 
were placed in the zirconia crucible and heated to 2910°. At 
this point the zirconium melted and took the shape of the cru- 
cible. These experiments led to the conclusion that the melt- 
ing point of zirconium metal is above that of molybdenum and 
very close to that of tantalum, probably about 2800° C. 

ALLOYS OF ZIRCONIUM. 

Probably the most interesting alloys of zirconium yet dis- 
covered are those with tin and with nickel. The former alloys 
are exceedingly pyrophoric when the zirconium content exceeds 
60 per cent, and in this respect resemble the well known cerium- 
iron alloys. 

Tin and zirconium alloy readily with evolution of heat at 
about 800° C, giving alloys of very high melting points. A 
composition containing approximately 25 per cent Zr and 75 
per cent Sn is very soft ; when heated to about 2000° C. most 



THE PREPARATION OF FUSED ZIRCONIUM. 



223 





224 HUGH S. COOPER. 

of the tin can be removed, the zirconium being left behind as 
an unfused mass. When 40 to 50 per cent Zr is present, the 
alloy begins to show pyrophoric properties when rubbed across 
a file, and at 60 to 80 per cent the action is marked. At 70 
to 80 per cent Zr the alloys probably equal the cerium-iron alloys 
in their scintillating effect. Because of their high melting point, 
it is not possible to produce rods and the like by casting, but 
these can be readily made by first pressing the zirconium metal 
into the desired forms and then heating these in the presence of 
powdered or ingot tin, the latter being rapidly absorbed. Com- 
positions containing as high as 90 per cent Zr can be made in 
this manner and these appear suitable for ignitors, etc. 

When used in percentages up to about 15, with small amounts 
of aluminum, silicon and tungsten or molybdenum, and with 
a base of nickel, excellent machine cutting tools are produced 
which retain their cutting edge at a red heat. 

Ternary alloys have also been made using manganese or anti- 
mony in connection with zirconium and tin, but these do not seem 
to offer any advantage over the binary compositions. 

Fairly high percentages of zirconium can be added to nickel 
before malleability is lost. The range of toughness probably ex- 
tends up to about 30 per cent. A 20 per cent alloy can be drilled 
and machined ; but when the zirconium approaches 50 per cent 
considerable hardness is manifested, together with some brittle- 
ness. These latter alloys can be produced only at a temperature 
around 1700° C. 

With gold, zirconium forms straw-colored brittle alloys for 
the production of which high temperatures are also required. 
The zirconium can be almost entirely removed from the gold 
by heating in an oxy-hydrogen flame. Attempts to make alloys 
with antimony and zinc were unsuccessful, as the metals vola- 
tilized away from the zirconium before alloying occurred. At 
about 1500° C. zirconium dissolves in copper. The effect is 
to increase the hardness with little change in color. Few alloys 
with lead were made and these seemed to disintegrate when ex- 
posed to the air for some time. Alloys with aluminum have been 
made in nearly all proportions, the action taking place at about 
1100° C. When the zirconium content is relatively low, consider- 



THE PREPARATION OF FUSED ZIRCONIUM. 225 

able toughness is manifested, but above 35 per cent brittleness 
prevails. Unlike the tin-zirconium series, the alloys exhibit no 
pyrophoric properties. The effect of zirconium on aluminum 
appears to be similar to that of silicon. 

Zirconium has been alloyed with magnesium by reduction of 
the oxide in vacuo, using a large excess of magnesium. Treat- 
ment with hydrochloric acid removes the magnesium without 
affecting the zirconium. If the zirconium is not too high the 
malleabihty of magnesium is not affected by addition of the 
latter. Alloys of tungsten can be produced by pressing the 
powdered mixed metals into briquettes. In this manner as 
much as 25 per cent Zr has been introduced. Forging properties 
of this series have not yet been investigated. 



DISCUSSION. 



J. W. Marden' : The paper given by Dr. Cooper is of interest 
to the speaker because, in collaboration with Mr. ]\I. N. Rich, he 
tried to make zirconium metal by the identical method described, 
using the Arsem furnace. The results of these investigations 
(which were made in 1919), were published in Bulletin 186, U. S. 
Bureau of Mines, 1921. Although we had some success, we 
found that it was nearly impossible to avoid some contamination 
when the zirconium was heated in the Arsem furnace. In more 
recent work in the laboratories of the Westinghouse Lamp Co., 
much better results have been obtained using an especially con- 
siructed high-frequency high-vacuum induction furnace, which 
has been described by Rentschler and ^vlarden before the Ameri- 
can Physical Society, April 20, 1923. 

Attempts were made to fuse zirconium in the Arsem furnace 
as described by Dr. Cooper, and the reasons for failure have 
been given on page 82 of the above bulletin, which dealt briefly 
with the impossibility of completely excluding oxygen and carbon 
in this kind of apparatus. Even when extreme precautions were 
observed, using a slow stream of pure dry H2 at the low pressure 
of a few mm., the introduction of carbon from the heating helix 

* Westinghouse Lamp Co., Bloomfield, N. J. 



226 DISCUSSION. 

and oxidation from the moisture always given off from the large 
amount of metal surface enclosing the furnace could not be 
eliminated. It is well known that the presence of oxide will 
raise the melting point considerably. 

Zirconium oxide crucibles were also used in some of the above 
experiments. The preparation of these crucibles is described in 
Bulletin 186. 

Bars of sintered zirconium were made in a vacuum treating 
furnace in the laboratory of the Westinghouse Lamp Company 
many months ago. The vacvmm used for this work must be of 
the highest type, using mercury diffusion pumps and liquid air 
traps. These bars have no superficial coating of oxide. It is of 
interest to bring out some of the points about the purity and the 
methods of analysis of the metal powder. The analysis of a 
metal powder is attended with extreme difficulty due to the vola- 
tile gas, either in free or adsorbed state. Wedekind has found 
that in a good vacuum these volatile gases can not be all removed 
from zirconium even at 1,000° C. We have found that zirconium 
powder often contains 2 to 9 per cent of moisture, hydrogen, 
loosely bound nitrogen, etc. Since zirconium increases only about 
30 per cent in oxidation there is often enough gas present in 
weighing the sample to indicate many per cent, of ZrO,. In the 
very painstaking work of Weiss and Neumann, they found for 
example that 0.1006 g. of zirconium yielded 0.1333 g. ZrOo. This 
corresponds to 98 per cent total zirconium, but only 91 per cent 
free metallic zirconium. 

Four years ago the writer could not obtain over 92.5 per cent 
free zirconium by the best methods of preparation. The purity 
of the powder was undoubtedly greater than that indicated, but 
the methods of analysis are not yet satisfactory for this work. 
Analyses should be stated in terms of free metal and not total 
metal. According to the results we obtained the method of des- 
iccation described by Dr. Cooper would not remove all of the 
gases. 

The melting point determination of zirconium, as with certain 
other of the rare metals, should be done with extreme accuracy, and 
these determinations must be made under conditions which preclude 
the possibility of the presence of oxygen or carbon. The metal 



THE PREPARATION OF FUSED ZIRCONIUM. 227 

which is used for this must be analyzed for oxygen and the per 
cent of oxide in the sample not inferred by difference, but be 
actually determined analytically. The melting point given by 
Dr. Cooper is near that of the oxide or the carbide. The melting 
point has been determined in the laboratory of the Westinghouse 
Lamp Company, and is not nearly as high as the value given by 
Dr. Cooper. Our metal melted sharply and did not show any 
gradual softening. The blistering or sweating of the high melt- 
ing point metals in the Arsem furnace may have been indicative 
of carbide formations. 

Ruff- has suggested the formation of carbide under such con- 
ditions as Dr. Cooper worked. This carbide was partially avoided 
in the work of Bulletin 186, U. S. Bureau of Mines, by the use 
of purified dry hydrogen to sweep away hydrocarbon vapors 
from the heating helix and moisture from the walls of the con- 
tainer. The melting point of pure zirconium is discussed on 
page 97, Bulletin 186. 

When the melting points of the metals are plotted against the 
atomic numbers, a regularity is observed which would indicate 
the melting point of zirconium about 1,700° C, or about 2,000° 
Abs. This may be somewhat too high or too low, but roughly 
indicates where it should be if the atomic number and atomic 
weight assigned to this element are correct. 

Lastly, the sintering of mixtures of tungsten and zirconium 
has been tried by the writer, and it is found that zirconium in a 
high vacuum distils away from tungsten at temperatures high 
enough for treating this metal. Pure metallic zirconium vola- 
tilizes rapidly below 2,800° C, where tungsten is treated before 
working. 

H. S. Cooper: It has been stated that the melting point deter- 
minations in the Arsem furnace were in effect comparisons be- 
tween zirconium carbide and molybdenum and tantalum, because 
it was thought that the zirconium would be converted to carbide 
in the atmosphere which prevails in a furnace of this type. 
There is no evidence, up to this time, that this occurs when zir- 
conium is the metal used. Our analyses have shown that there 
is only an absorption of carbon to an extent of about 0.2 per cent 

= Z. Electrochemie, 24, 157 (1918). 



228 DISCUSSION. 

when the metal is heated to its melting point, and it is unlikely 
that this amount of carbon would materially affect the results 
in either direction. 

In all of our work we have been careful not to use amorphous 
zirconium, as we have found that this grade of metal is apt to 
contain oxygen to an appreciable extent. Two grades of metal 
exist after reduction, and we have been careful to pick clean, 
bright samples, which are then pressed into the rods which I 
have described. When such rods are used in the Arsem, I 
seriously question whether there can be any combination with 
oxygen, as the furnace atmosphere is decidedly reducing, which 
is evidenced by the discoloration that you have noted on the 
zirconium oxide crucibles. This change of color on the crucibles 
is not due to carbon or carbide, but is an actual reduction of the 
oxide to metallic zirconium, which has been proved. 

Mr, Marden's criticism on the use of the Arsem furnace for 
these experiments seems to me to be rather misdirected, in view 
of his statements under the title of "Preparation of Coherent 
Metal in Arsem," on pp. 94 and 96 of the Bureau of Mines Bul- 
letin No. 186 — "Thus the experiment had accomplished what had 
been considered impossible, namely, the fusion of the amorphous 
metal." The analyses with this statement is what might be 
expected by the use of amorphous metal. 

It is rather strange that having a product of a purity indicated 
by the various analyses discussed in the bulletin, that IMr. JVIarden 
was unable to produce an alloy of zirconium with tin, as these 
alloys are simply prepared. If I have correctly interpreted the 
remarks made by this gentleman there appears to be some doubt 
in his mind that the zirconium-tungsten alloys can be prepared in 
the manner outlined, since he has stated "that in his experience 
the former metal boils away from the latter before alloying 
occurs." In this connection I wish to state that we have prepared 
a great many alloys of zirconium and tungsten. These were made 
by thoroughly blending the powdered zirconium with powdered 
tungsten, pressing the product into rods, sintering the rods in 
vacuo and then heating the same by their own resistance up to 
about 2,200° C. There can be no doubt that alloys of any desired 
percentage of either metal can be prepared in this manner, and 



THE PREPARATION OF FUSED ZIRCONIUM. 229 

contrary to Mr. Marden's statement, if any evaporation of the 
zirconium does occur the amount is so slight as to be invisible 
on the surface of the o^lass enclosure in which the experiments 
were conducted. 

W. C. Arsem" {Communicated) : It should be remembered 
that in a vacuum furnace the character of the results de- 
pends on the maintenance of a vacuum as good as can be obtained. 
The best results are not to be expected unless the pressure is kept 
low, probably around 1 to 10 microns. It is not sufficient to 
maintain a fairly good vacuum by an efificient pump acting against 
a continuous leak in the furnace. Leaks should be absent. In 
order to guard against leaks it is necessary to make sure of the 
absolute tightness of both electrode and cover gaskets by appro- 
priate tests. The technique for realizing this condition should 
be quite obvious, although it is often carried out imperfectly 
through failure to recognize its importance. 

A furnace with graphite parts, allowed to stand open to the 
air when not in use, absorbs and condenses a considerable amount 
of air and moisture, and to avoid this condition it should be kept 
exhausted when not in use. When experiments are to be tried 
in high vacuum it is best to run the furnace under experimental 
conditions without a charge until gases are well removed and a 
high vacuum can be maintained at a high temperature, then let 
it cool under exhaust and open it with the temperature of the 
cooling water above the dew-point to avoid condensation of mois- 
ture. Then insert the charge, exhaust immediately and continue 
to exhaust at low temperature until a high vacuum is obtained 
before applying the current. 

The presence of oxygen or water in the interior means that 
the atmosphere will eventually be chiefly carbon monoxide. This 
is not a "reducing" atmosphere except under special conditions. 

With many of the metals whose oxides are extremely stable we 
have at high temperatures the following reactions : 

CO -f M ±5 ^lO -f C 
and 

CO 4- 2^1 ±5 ^lO -\- MC 

' Consulting Chemical Engineer, Schenectady, N. Y. 



230 DISCUSSION. 

The action which takes place is really more complex than the 
equations indicate, but the net result is that a mixture of oxide 
and carbide can be formed at least superficially by heating certain 
metals in an atmosphere of CO. 

It would be advisable in reporting results of research of this 
kind to include in the paper a complete log of each furnace run, 
including pressure readings. Absence of these data may lead to 
much misunderstanding and uncertainty. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City May 5, 1923, Dr. F. M. Becket in 
the Chair. 



EXPERIMENTS WITH URANIUM, BORON, TITANIUM, CERIUM 
AND MOLYBDENUM IN STEEL 



By H. W. GiLLETT and E. L. Mack.* 

Abstract. 

Of U, B, Ti, Zr, Ce and Mo used as alloying elements in heat- 
treated steels, only Mo has a decided and consistently beneficial 
effect. In the types of steel in which the other elements were 
used they were either of slight effect one way or the other, or 
decidedly harmful. 

U probably has a slight strengthening effect, but similar results 
can be obtained by cheaper means. B and Ce are harmful. Ti 
and Zr have about as much effect as equal amounts of Si. 'Mo is 
a real and potent alloying element. 



When the Bureau of Alines was actively studying radium pro- 
duction it was thought desirable to study the preparation of ferro- 
uranium, and this work was assigned to the writers.^ This gave 
a stock of ferro-uranium. On account of reported German use 
of U steel, the Watertown Arsenal requested that an experi- 
mental series of U steels be made up and supplied to the arsenal 
for study. Later, further series of W, j\Io and other steels were 
requested. Since the Bureau was equipped for this sort of small- 
scale work, the navy then requested the preparation of some high 
Si-Ni steels, containing Zr. In that connection, Ce and B were 
also added to this Ni-Si steel. 

In the above work, the Bureau merely prepared and analyzed 

* Published by permission of the Director of the Bureau of Mines. Manuscript 
received January 30, 1923. 

* Department of Interior, Bureau of Mines, Ithaca, N. Y. 

' Gillett, H. W., and Mack, E. L,., Preparation of ferro-uranium, Tech. Paper 177, 
Bur. of Mines 197. 

231 



232 H. W. GILLETT AND E. L. MACK. 

the steels, the testing being done by other departments or 
bureaus.^"* Co-operative agreements were later made with the 
\\'elsbach Co. for a further study of Ce steel, and with the 
Vanadium Corporation of America for a study of various types 
of Mo steel. These latter series have been tested by the Bureau 
of Mines and a comprehensive series of endurance tests on them is 
still under way. As regards data on the physical properties of 
the other steels, these are wholly lacking in the case of the steels 
prepared for the arsenal, and in the case of most of the steels of 
the Ni-Si-Zr series they are fragmentary, in that only normalized 
specimens and specimens subjected to a single heat treatment 
and that at a very low draw temperature were tested. 

Detailed data on the preparation of the steels, especially in 
regard to recovery of the alloying elements, have been fully given 
elsewhere,^ and will be only briefly touched on here. 

The steels were made up in 50 to lOO-lb. heats in an indirect arc 
furnace. Ferro-alloys of readily oxidizable alloying elements 
were usually added at the end of the heat, just before pouring. 
Armco iron was used as the base, by which means sulfur was 
held to 0.035 per cent, usually below 0.030 per cent and P to 
below 0.02 per cent, usually below 0.015 per cent. 

URANIUM. 

Since the arsenal desired a number of steels of high U content, 
attempts were made to prepare these. Steels analyzing 2 per cent 
U and over were prepared, but usually shattered in forging. 
Steels analyzing over 0.55 per cent U were slushy when poured, 
although very hot, and all such steels showed terrific segregation 
in different parts of the ingot. To get a uniform U content of 
0.35 to 0.50 per cent U it was necessary to add over 1 per cent of 
U as ferro-uranium, ferro-uranium alloy low in C and high in U 
giving the best results. 

Physical tests (Bureau of Standards, small round test bars 
cut from plates one-half in. thick) were made only on some of 

* Wheeler, H. E., Nitrogen in Steel and the Erosion of Guns, Trans. Am. Insi. Min. 
and Met. Eng. 47, 257 (1922). 

* Burgess, G. K., and Woodward, R. W., Manufacture and Properties of Steel 
Plates containing Zirconium and other elements. Tech. Paper 207, Bur. of Standards, 
1922. 

» Gillett, H. W., and Mack, E. L., Experimental Production of Alloy Steels, Bull. 
199, Eur. of Mines, 1922. 



EXPERIMENTS WITH RARE ELEMENTS IN STEEL. 



233 



the non-segregated Ni-Si steels, to which uranium was added. 
These are given in Table I, together with a couple of comparison 
steels without U. 

Table I. 

Physical Tests on Alloyed Steels. 

Normalized from 800 to 840° C. 



Steel 
No. 


c 


Si 


Mn 


Ni 


u 


Yield 
Point 


Tensile 


El 


1244 

1229 
1228 
1327 
1227 
1237 


0.43 
0.45 
0.63 
0.45 
0.40 
0.49 


1.30 
1.05 
1.20 
2.42 
1.45 
2.20 


0.90 

0.75 
0.84 
0.70 
0.84 
0.94 


3.00 
3.00 
3.00 
2.92 
3.10 
3.05 


0.34 
0.36 
0.37 
0.52 


134,000 
234,000 

169,000 

* 

97,000 
108,000 


184,000 

240,000 
176,000 

134,000 
156,000 


6 
3 

0.5 

18.5 
14.5 


steel 


Red. 


Brinnell 


Heat Treated. Quenched from 800-840° C. in oil; 
175° C. draw. 


No. 


Yield 
Point 


Tensile 


El. 


Red. 


Brinnell 


1244 

1229 
1228 


13 

8.5 
2.5 

52 

41 


290 
315 
305 


195,000 
192,000 


310,000 
283,000 
300,000 


10.5 
2.5 
1 


35 

8.5 
3.5 


625 
530 
620 


1227 
1237 


265 
315 




205,000 
258,000 


286 
313 


000 
000 




8.5 
8 


39 
25 




555 
530 



* Broke in rolls. 

The normalized U steels showed a martensitic pattern, and 
were stronger and less ductile than the comparison normalized 
steels. The heat-treated steels with U show on the average no 
appreciable improvement over those without. The U steels 
contain characteristic blue inclusions. While great claims have 
been made for U in high speed steel and in ordinary steels, the 
first seem open to grave question and the second seem to be cov- 
ered by the comment of Poluskin*^ to the efifect that, while U may 
somewhat increase tensile strength and toughness without loss of 
ductility, it does nothing that cannot be done with cheaper alloying 
elements. He thinks much of the U in steel is present as oxide. 

The cost of U, the difficulty of introducing it without excessive 
loss and without the formation of dangerous inclusions, together 

8 Poluskin, E. Les aciers al' uranium. Rev. de Met., 17, 421 (1920). Iron Trade 
Rev., 68. 413 (1921). Iron Age, 106, 1512 (1920). 

16 



234 ^- "^^^ GILLRTT AND E. L. MACK, 

with the cessation of mining of domestic carnotite, make uranium 
steel arouse httle enthusiasm at present. Were its alleged 
advantages more outstanding or the supply of U larger, it would 
deserve further study. It might have use as a scavenger, but it 
has not impressed us as promising on this score, as its oxidation 
products do not appear to be readily released by the steel. 

BORON. 

Since B is reputed to give great hardness to steel some C-B 
and Ni-Si-B steels were made up. The only ferroboron avail- 
able was the thermit product. One lot contained two-thirds as 
much Al as B and another one-third as much. The ferro-alloy 
was readily taken up. Adding it at the end of the heat, 90 per 
cent of the B or better was recovered. Even when charged at the 
start of the heat, an 80 per cent recovery was made. Analyses of 
different parts of the ingots showed no segregation of boron. 

The B steels with around 0.10 per cent B, and with a C content 
of 0.15 to 0.70 per cent, had an amazing freezing range. They 
started to solidify about the usual temperature, but did not 
become fully solid till the temperature dropped down, somewhere 
around the melting point of cast iron. 

During the long freezing range the ingot was plastic, and when 
poked it acted like pie crust under the cook's thumb. There is 
plainly a very low-melting carbon-iron-boron eutectic. This is 
clearly shown metallographically. Aloreover the first couple of 
ingots of boron steel rolled by the Bureau of Standards fell to 
pieces of their own weight when heated to the usual rolling 
temperature and picked up by tongs, so that the preheating 
temperature had to be reduced. 

With 0.30-0.50 per cent B even low carbon steels lost a great 
deal of their ductility, and even 0.06 per cent B spoiled a 0.45 per 
cent C steel for heat treating. The B eutectic in the cast material 
is a network, but this can be broken up and spheroidized by hot 
working (possibly also by thermal treatment), and in that state 
the steel is not so brittle. Heating to a normal temperature for 
quenching causes a network to reappear and gives a brittle 
product. 

It is within the bounds of possibility that the steels might be 
handled so as to be good for something, but hot-working 



EXPERIMENTS WITH RARE ELEMENTS IN STEEL. 235 

processes as used on other steels do not produce anything worth 
having. A purely scientific study of the Fe-B-C system would be 
highly interesting. One wonders what B might do in cast iron. 

If B is to be used as an alloying element, the steels will have to 
be given special treatment, and, lacking a detailed preliminary 
scientific study, it is hard to see how they can be commercially 
useful. 

In regard to boron as a scavenger, the fact that it gives a high 
recovery even when added at the start of the heat indicates that 
it cannot be expected to have strong deoxidizing action. If it will 
act as a deoxidizer it might, by the formation of the oxide, tend 
to flux out other oxides and hence be beneficial. One thinks at 
once of boron nitride and of the possibility that it would remove 
nitrogen. In a British patent, Walter,^ a German, says that, 
while 0.2 per cent or more B causes brittleness, anywhere from 
0.001 to 0.10 per cent B causes astonishing grain refinement in 
steel, and that similar amounts in cast iron give stronger material 
with graphite in spherical form. One would be more impressed 
by his claims if he did not state also that from 0.007 to 0.01 
per cent B in a C steel makes it self-hardening. 

The writers are inclined to feel that, while, on the face of 
returns, boron does not appear to be of any use in steel, a sys- 
tematic study of B in steel might show greater possibilities than 
can be seen at present. This view is based on the fact that B 
has a real efifect and gives a product with peculiar properties, 
which might conceivably be utilized. 

TITANIUM. 

For comparison with Zr steels, which carry some Ti, various 
plain Ti and Ni-Si-Ti steels were made, using a thermit ferro- 
titanium containing about one-fourth as much Al as Ti. Adding 
this at the start of the heat, around 20 per cent of the Ti was 
recovered, while, by adding it at the end of the heat, around 65 
to 70 per cent was recovered. Steels were made with up to 2 
per cent Ti. Segregation of Ti was not troublesome. The steels 
containing Ti as alloying element were certainly no better, and 
generally somewhat less ductile than comparison steels without 

' Walter, R., British Pat. 160. 792, Aug. 23. 1921. 



236 H. W. GILIvETT AND E. L. MACK. 

Ti. Steels with only a few hundredths per cent of Ti showed no 
superiority over the comparison steels. 

ZIRCONIUM. 

The work on Zr was required because of the high recom- 
mendation given a Ni-Si steel carrying Zr, by Mr. W. H. Smith 
of the Ford Motor Co. While "zirconium steel" was loudly 
heralded, it is only fair to say that Mr. H. T. Chandler, formerly 
with the Ford Motor Co., the metallurgist in actual charge of the 
Ford experimental work with Zr, considered the value of this 
steel to lie chiefly in the Ni-Si combination, with the possibility 
that Zr added something to that combination. 

As a result of the agitation for Zr steel, much baddeleyite was 
imported from Brazil at a time when shipping was precious, and 
ferro-alloy manufacturers had to displace the production of ferro- 
alloys of proven value for that of ferrozirconium. The navy was 
not stampeded by the agitation, but decided to find out what, if 
any, virtue lay in the Zr. 

In the work done by the Bureau of Mines for the navy, some 
75 Zr steels, and an equal number of comparison steels without 
it, were made in the preliminary work in which the steels were 
rolled, heat treated (normalized and given a quench and a single 
low temperature draw) and tested for mechanical properties by 
the Bureau of Standards. In the later work a series of some 30 
steels, with and without Zr, was made by the Bureau, rolled, and 
each given three or four different heat treatments by the Halcomb 
Steel Co. and tested for mechanical properties by the navy. 

Although thermit ferrotitanium was found to give fair recov- 
ery of Ti, thermit ferrozirconium did not, the recovery of Zr 
averaging not over 10 per cent. 

Various electric furnace ferro-alloys reduced by C, and carry- 
ing considerable C, made by the Bureau of Mines and by the 
Southern Manganese Co. also gave a low recovery, averaging 
under 5 per cent. 

Electric furnace ferro-alloys made by the Bureau, using Si as 
reducing agent, gave 60 to 80 per cent recovery. An electric 
furnace ferro-alloy, low in Si, made by the Electro Metallurgical 
Co., with Al as reducing agent, gave around 10 per cent recovery, 
but an alloy similarly made but in place of Fe containing 55 per 



EXPERIMENTS WITH RARE ELEMENTS IN STEEL. 237 

cent Ni, gave 40 per cent recovery, while the Electro Metallurgical 
Go's Si-Zr (30 per cent Zr-45 per cent Si, reduced by C in the 
presence of Si) gave a 55 per cent recovery. 

In the second series, using Electro Metallurgical Go's ferro- 
alloy, the Si-Zr gave a 50 per cent recovery, Xi-Zr 50 per cent 
and a Si-Ni-Zr (27 per cent Zr, 22 per cent Ni, 35 per cent Si) 
made by melting together Si-Zr and Ni-Zr, 65 per cent. 

To get these recoveries, the Zr alloy had to be added at the 
end of the heat. If added at the start, the steel contained only 
traces of Zr. When remelting crop ends containing 0.20-0.25 
per cent Zr and 0.03 per cent Ti, the steels came out with no 
trace of Zr and under 0.01 per cent Ti. 

When we consider the loss of Zr in making the ferro-alloy 
from ore, that from ferro-alloy to steel, and that in remelted 
scrap containing Zr, the recovery from ore to finished steel would 
not be over 40 per cent and probably well under that figure. 

No matter what the Zr alloy used, steels finishing with from 
0.30 to 0.80 per cent Zr regularly showed a segregation of Zr, 
the top of the ingot containing say 30 per cent more Zr than 
the butt. 

The Ni and Si introduced by the Ni-Zr, Si-Zr or Ni-Si-Zr 
alloys did not show segregation. With not over 0.25 per cent in the 
finished steel, segregation of Zr is negligible. Full details as to 
recoveries and segregation can be found in the report^ on the 
preparation of these steels. 

The physical tests on the Ni-Si-Zr and comparison steels of 
the first series can be found in the rep.ort of the Bureau of 
Standards.® 

The sum total of the tests by all the co-operating government 
agencies led to the conclusion that the Ni-Si steels have good 
mechanical properties ; that these properties, measured by the 
ordinary tensile and impact tests, are not materially injured by 
the introduction of small amounts of zirconium. Neither did 
it appear that the properties were materially enhanced. A steel 
of 0.40 C, 1.45 Si, 0.85 Mn, 3.00 Ni, rolled to one-half in. from 
a 3 X 3-in. ingot, normalized from 840° C., gives, on 0.3-in. diam- 
eter by 2-in. gauge length round specimens, a yield point of 

5 Gillett, H. W. and Mack, E. L., Experimental Production of Alloy Steels, P>ull. 
199, Bur. of Mines 1922. 
^Burgess, G. K., and Woodward, R. W., he. cit. 



238 H. W. GILLETT AND E. L. MACK. 

around lOO.OCX) and a tensile strength of around 140,000 lb. per 
sq. in., with an elongation of say 15 per cent and a reduction of 
area of say 40 per cent with a Brinnell hardness of around 270. 
On quenching from 840° C. and drawing 3 hours at 175° C, it 
gives a yield point of around 240,000 and a tensile strength 
around 280,000 pounds per sq. in., with an elongation of about 
9 per cent and a reduction of area of 30 per cent, a Brinell of 
around 550, and (on a standard Izod bar) around 9 to 12 foot- 
pounds on the Izod test. The elongations would be higher on a 
standard 0.505-inch tensile bar. 

With 0.10-0.40 per cent Zr similar steels show a tendency 
toward higher tensile strength and hardness, and lower ductility 
in the normalized state, and approximately the same properties 
with perhaps lower ductility under the heat treatment given. 
The better Zr steels of this class do not contain much over 0.15 
per cent Zr. The tests on Zr steels show rather more variation 
among steels of about the same composition than those on plain 
Ni-Si steels. Since the problem w^as concerned with these steels, 
and it was necessary to use Si-Zr alloys which introduced a good 
deal of Si, nothing was done with plain C low Si steels containing 
Zr. A few high Si-C steels were made with and without Zr, but 
these, like the Ni-Si steels, show no regular beneficial effect due 
to Zr. 

A few tests on the addition of Mo or V to the Ni-Si steels did 
not materially change the results either on the normalized steel 
or on that given the quench and low draw. 

So far the evidence was against any beneficial effect from Zr 
at least in the Ni-Si steels, but another series was made on which 
each steel had three or four different treatments, higher draw 
temperatures being used. These steels were cast in 3 x 6-in. 
ingots and were rolled to plates one-quarter inch thick, being 
spread to a little over 12 in. wide by cross-rolling, then straight- 
rolled, reheated and finished by straight-rolling. 

For the physical tests, made by the navy, tensile bars 0.5 in. 
wide by 0.25 in. thick by 2 in. gauge length, were cut from the 
plates with a 0.06 in. emery wheel, being finished by hand. The 
bars were shouldered and held in wedge grips. Izod specimens 
were also cut, 10 mm. wide by thickness of the plate. The notch 
was cut by a shaper tool, being 2 mm. deep with 1 mm. radius 



EXPERIMENTS WITH RARE ELEMENTS IN STEEE. 239 

at the bottom (Mesnager notch). The direction of impact was 
parallel to the surfaces of the plate. The Izod values were com- 
puted to standard square Izod bar size by means of the ratio of 
standard 10 mm. width to the plate thickness. Two notches were 
tested on each Izod bar. Both tensile and impact specimens were 
taken in both longitudinal and transverse directions. 

Steels of 0.35-0.40 C and 1.50-2.25 Si (or Si -f Zr + Ti) gave 
very uniform results between longitudinal and transverse bars 
on ductility and Izod tests. With higher carbon or silicon (or 
Si -|- Zr -|- Ti) or both, the transverse bars generally fell below 
the longitudinal ones on these tests. Tensile strength and elastic 
limit were of course closely the same on bars taken in either 
direction on all the steels. 

If we assume that Zr or Ti are approximately equal to equiv- 
alent amounts of Si, and plot the properties of the different 
classes, we get, for the average compositions given in Fig. 1, the 
properties plotted, for bars taken longitudinally. By comparison 
with the data obtained by the Bureau of Standards^" for some 
similar steels drawn at 175^ C. and from some Navy data not 
plotted in Fig. 1, it will be found that with draw temperatures 
below 400° C, the strength continues to increase while the 
ductility remains about the same as at the 400° draw. Raising 
the C or Si too high causes the ductility to increase with increas- 
ing draw temperature only slightly, and gives a dip in the Izod 
curve with a minimum around a 525° C. draw. 

The navy Izod figures are on bars with the Mesnager notch 
(1 mm. radius at base) and were taken on rectangular bars and 
calculated to a 10 mm. square bar. The Bureau of Standards' 
Izod figures are on round bars, with the one-quarter mm. radius 
V notch, computed to the standard round bar of 1 sq. cm. area. 

The British automobile steel research committee, whose results 
on alloy steels would be interesting to compare with this steel, 
used square bars with one-quarter mm. radius notch. Conver- 
sion factors, especially between the two notches, are so unsatis- 
factory that no direct comparison can be made of the Ni-Si 
steels and other alloy steels as to impact results. Also, because 
the Ni-Si steels had to be tested in flat bars, the ductility figures 
do not compare exactly with data on other steels from round bars. 

•0 Burgess, G. K. and Woodward, R. W., he. cit. 



240 



H. W. GILLETT AND E. L. MACK. 



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EXPERIMENTS WITH RARE ELEMENTS IN STEEL. 24 1 

The Steel requires higher draw temperatures to soften it than 
plain Ni, or the ordinary Ni-Cr steels. It will therefore be pos- 
sible to draw the steel at temperatures high enough to make 
fairly certain that quenching stresses are released, and still get 
a high tensile strength combined with good ductility and tough- 
ness. The steels are especially attractive at draw temperatures 
around 400° C, for springs, and possibly for gears, or other 
use, where great strength or hardness combined with toughness 
is desired. Moreover, around this draw temperature, there is a 
fair range of compositions through which about the same physical 
properties are obtained. 

The steels rolled well and, in the simple shape in which they 
were heat treated, did not show quenching cracks. We do not 
know what they would do in complicated shapes. 

All the Ni-Si or Ni-Si-Zr steels within the limits of composi- 
tion tested gave good and uniform results at the 400° draw. 
Results at draw temperatures of around 500° C. were less 
uniform. 

Up to around 0.30 per cent Zr the effect of Zr seems to be 
negligible, or at any rate no more noticeable than the addition of 
an equal percentage of silicon. Putting in 0.40 to 0.75 per cent 
Zr consistently decreased the toughness and such steels, as well 
as those with too much C or Si gave much more erratic results, 
especially on transverse bars. One might expect that these high 
Si steels would tend to throw out graphite readily and that the 
impaired toughness of the higher C, high Si steels might be due 
to this cause. Microscopic examination, however, has not shown 
any deposition of graphite in these steels. 

The steels lower in C and Si can just be machined in the nor- 
malized condition. Cooling in lime made it possible to crop all 
the ingots, of whatever composition, by sawing, though those 
high in C and Si would be classed as steels difficult to machine. 

The results of the second series of Zr steels agreed with the 
indications of the first, to the effect that the virtues of the so- 
called "Zirconium" (Ni-Si-Zr) steels were due to the combina- 
tion of Ni^^ and Si rather than to Zr. Zr probably has no greater 
effect in this type of steel than so much Si. Zr leaves tiny, sharp- 

'1^ Compare Hoyt, S. L. Metallography Part II, p. 358, 1921, for properties of similar 
steels without nickel. 

17 



242 H. W, GILLETT AND E. L. MACK. 

cornered inclusions in the steel, and it is more desirable to have a 
steel free from such inclusions. 

As to the possibilities of Zr as a scavenger, some very good 
steels were made by remelting crop ends containing Zr, the 
resulting steels coming out with only a few hundredths of one 
per cent Zr. On the other hand, equally good plain Ni-Si steels, 
into which no Zr entered, were also made. Johnson^- has studied 
the Ni-Si steels and has also concluded that Zr and Ti did not 
have any beneficial effects. The compositions of his steels are 
given in general terms only, so that no real comparison with our 
results can be made. 

CERIUAI STEELS. 

Cerium being in the same group in the periodic system as Zr and 
Ti, some work on Ce was done in connection with that on Zr. Since 
the early work showed that Ce had a desulfurizing action, further 
work on this point and on its possibilities as an alloying element 
was done in co-operation with the Welsbach Co. Some "mop- 
ping up" on endurance tests on this problem is still under way. 

Mix metal (Ce, La, Nd, Ph and Sa) was used to introduce Ce, 
and the word "cerium" and all calculations involving percent- 
ages of "cerium," hereinafter refer to the Ce group of metals 
thus introduced. 

By adding 0.50 to 1.0 per cent Ce to the steel just before pour- 
ing, we have reduced S from 0.155 per cent to 0.067 per cent, 
from 0.085 per cent to 0.45 per cent and from 0.035 per cent to 
0.015 per cent. A strong SO2 odor and the rising of a reddish 
slag indicates that S combines with Ce and rises to the surface, 
where the S burns out. When less than 0.50 per cent Ce is 
added, desulfurization is slight. Adding 1 per cent Ce as soon as 
the charge is melted removes only a little S and no Ce is found 
in the steel. 

Desulfurization by Ce thus appears to require the addition of 
so much Ce at the end of the heat that some will be left in the 
steel, and its use would depend on what the residual Ce does to 
the steel. Somewhere from 5 to 45 per cent of the Ce added at 
the end of the heat is all that is retained in the steel, and if much 
is retained it segregates badly. Such figures as 0.60 per cent Ce 

^^ Johnson, C. M., some alloy steels of high elastic limit, their heat treatment and 
microstructure, Trans. Am. Sec. for Steel Treat., 2, 501 (1922). 



EXPERIMENTS WITH RARE ELEMENTS IN STEEE. 243 

in the top and 0.30 per cent in the butt of a 70-lb. ingot are com- 
mon. If not over 0.25 per cent Ce is retained, there is little 
segregation. 

We have not been able to make steels containing over 0.30 to 
0.40 per cent Ce in 3 x 6-inch ingots of 75 to 100 lb. without 
having the ingots unsound through the formation, at least in the 
top of the ingot, which freezes last, and often clear to the butt, 
of very tiny hair cracks not visible without smoothly machining 
the cross section of the ingot. Microscopic examination shows 
that there are literally myriads of tiny inclusions in a Ce steel, 
and that if there is enough Ce present and enough time given for 
it to act, these inclusions tend to coalesce and rise. If enough 
large coalesced inclusions are present to be collected between the 
crystals as the steel freezes, they cause these inter-crystalline hair 
cracks. Possibly if enough time could be given, all the inclusions 
would coalesce and rise, but, working with not over 100 lb. of 
steel, it could not be held long enough in the ladle. 

The inclusions, under high magnification, are grayish, some- 
times mottled with orange. They are roundish in the ingot. On 
rolling or forging the steel the inclusions smash up a trifle so as 
to have more irregular outlines, but are still more or less roundish. 
They do not draw into hair-like or knifeblade-like forms during 
the rolling of rods and plates as manganese sulfide does. Inci- 
dentally, the woody fracture of a transverse specimen of a rolled 
plate that contains ordinary inclusions may be due to the fact that 
the inclusions roll out too, for one such plate which is very dirty 
from inclusions of Ce does not show a woody fracture, while com- 
panion plates, free from Ce and immeasurably freer from inclu- 
sions, all showed woody transverse fractures. Rolling or forg- 
ing, while it does not flatten or draw out the individual inclusions, 
often spreads the shattered inclusions in well-defined lines, so 
that rods of Ce steel are often seamy and plates laminated. 

It is probable that the S of the Ce steel is held in these inclu- 
sions not as manganese sulfide, as in ordinary steel, for the in- 
clusions are larger and in greater mass though not usually in 
greater numbers, in the top of the ingot, and the S is often de- 
cidedly higher in the top of the ingot than in the butt, the ratio 
of segregation being usually higher than that of the Ce present. 



244 H. W. GILLETT AND E. L. MACK. 

Starting with material of 0.03 per cent S, it was rare that the 
butt of an ingot of Ce steel would run over 0.01 per cent S. 

On the other hand, if all the inclusions contain S, the per- 
centage of S in them must be very low. It could not be present 
as any orthodox cerium sulfide and account for the great mass 
of inclusions. The inclusions are probably of complex composi- 
tion, and one would naturally suppose them to be mostly oxides. 
That the S is combined with the Ce is probable from the be- 
havior of a couple of steels in which the Mn was kept as low 
as possible (and in one case extra S added) and the steel treated 
with 1 per cent Ce. One of these, a 0.30 per cent C steel, was 
made up for 0.069 per cent S. It came out with 0.032 per cent 
S, 0.06 per cent Mn and with 0.05 per cent Ce left out of 1.10 
per cent Ce added. Theoretically, 0.055 per cent Mn is re- 
quired to combine with the S present. Practically, on account 
of mass action, it is generally considered that much more Mn 
would be required to prevent the presence of FeS, so that such 
a steel would be expected to be red-short. However, the steel 
forged nicely. Physical tests show no difference from any steel 
of that general composition. No Al or other special deoxidizer 
was used, but the Si was raised to 0.65 per cent to compensate, 
in killing the steel, for the low Mn. Some tests have been made 
using 0.01 to 0.03 per cent Ce as final deoxidizer which pro- 
duced dead, de-gasified steel on high silicon steels, but 0.06 per 
cent Ce failed to kill a low Si steel. Ce is not as strong a deoxi- 
dizer and de-gasifier as aluminum. 

Part of the Ce, or at least of some one or more of the Ce group, 
of metals, is probably present as carbide, for the steels con- 
taining more than something between 0.10 and 0.20 per cent Ce 
have a decided acetylene-like odor. Steels high in Ce give out 
a strong odor on machining. All one has to do to pick out 
such a Ce steel from among others is to rub it with emery paper 
or even with a rubber eraser, so as to remove some invisible 
film, and the characteristic odor will be easily detected. 

With the low and irregular recovery of Ce, irregular desulfuri- 
zation, the prevalence of cracked ingots and the great number 
of inclusions, it is difficult to get steels by which one can de- 
termine the real alloying effect, if any, of Ce. In the Ni-Si 



EXPERIMENTS WITH RARE ELEMENTS IN STEEL. 245 

and in Ni-Cr steels, there is some evidence that 0.20 per cent 
Ce increases the propensity toward air-hardening, i. e., that it 
acts as a true alloying element. But the ever present inclu- 
sions so complicate matters by reducing ductility that we are 
unable to state what would be the properties of a steel contain- 
ing Ce as alloying element and none as non-metallic inclusions. 

Tests have been made on plain Ce, Cr-Ce, Ni-Si-Ce, and Ni- 
Cr-Ce steels. A 0.45-per cent C, 1.30-per cent Si, 2.95-per cent 
Ni steel tested by the Bureau of Standards gave (oil quenched 
and drawn at 175° C.) 311,000 Ib./sq. in. tensile and Z7 per cent 
reduction of area at a Brinnell of 555. On this 0.02 per cent Ce 
was used as final deoxidizer. Other steels containing more Ce 
showed similar strength but lower ductility. A couple of these 
showed very good impact tests and hence all the Ce steels made 
since have been given the Izod test on samples drawn at low 
temperatures. However, none of these other Ce steels have 
shown any exceptional impact results. 

Generally speaking, the forged or rolled Ce, Cr-Ce and Ni- 
Cr-Ce steels, containing 0.20 to 0.50 per cent Ce quenched and 
tempered, are practically indistinguishable on tensile, impact 
or repeated impact tests from similar steels without Ce, when 
test bars taken longitudinally are considered. Transverse test 
bars from plates fall down on ductility, doubtless due to the 
inclusions. 

When we come to the "fatigue" test, endurance against re- 
peated bending, the Ce steels regularly fall down in comparison 
with similar steels free from Ce, and this is the more noticeable 
the harder the steel. This test is probably more sensitive to 
the presence of inclusions than any of the other mechanical tests, 
and the poor behavior of the Ce steels is obviously due to the 
inclusions. In fact, if one looks at a micrograph of a Ce steel, 
taken from a polished but unetched section to show inclusions 
(see Fig. 2-5) he wonders why such dirty steel does not give 
poorer results on all tests than it does. The endurance tests 
show that, due to the inclusions, the cerium steels, especially 
when treated to a high hardness, are highly unreliable against 
repeated bending. 

It is possible that some means might be found to control and 



246 H. W. GILLETT AND E. L. MACK. 






>• 



Img 2. Unetched Cross Section of Fig. 3. Unetched Longitudinal Sec- 

Cerium Steel. X 100. tion Cerium Steel, x 100. 






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Fig. 4. Unetclied Cross Section Fic. S. Unetched Cross Section 

Cliromium-cerium Steel, x 100. Chromium-cerium Steel, x 100. 



e;xpe;riments with rare elements in steel. 247 

utilize the desulfurizing action of Ce without doing more harm 
than good by the retaining of inclusions. We came close to this 
with a couple of steels low in manganese, but would be unwilling 
to attempt it on a production basis. 

Cerium has been claimed to increase the ductility of aluminum 
alloys, and we tried'" it out in various light aluminum casting 
alloys, including the duraluminum type, both as cast and heat- 
treated, but were unable to find any improvement of any sort 
due to cerium. 

MOLYBDENUM 

After working with U, Zr and Ce, which give low and vari- 
able recoveries, leave inclusions in the steel, segregate and either 
have little effect on or do actual harm to the steel, it is a relief 
to work with an alloying element that enters the steel without 
loss, does not segregate, and has a positive and very beneficial 
effect on the steel. 

Most of the elements above mentioned are not available in 
this country in large quantities. Mo, on the other hand, is an 
element of which the United States has an an ample supply, and 
a complete understanding of just what it does in steel is import- 
ant in the development of our Mo resources. 

Present-day alloy steels for such uses as automobiles and air- 
craft require one or more of the following elements — Mn, Si, 
Ni, Cr, V. The first two are not usually classed as alloying ele- 
ments, since they are present in all steel, but in amounts above 
the normal, they do exert an influence that justifies classing them 
as alloy elements. 

The great bulk of the Ni used is mined in Canada. The V 
comes from Peru. Though we can, at a pinch, supply some Cr 
and Mn, the Cr usually comes from New Caledonia, Rhodesia 
and Asia Minor, and the Mn from Brazil and Caucasia. Fe, 
C and Si are domestic. 

The development of a home supply of an alloying element 
which can, in whole or in part, replace or supplement the ele- 
ments of foreign origin, is of obvious importance. One de- 
posit in Colorado contains enough Mo to make some 20 million 

'3 Gillett, H. W., and Sclinee, V. H., Cerium in Aluminum Alloys, soon to be pub- 
lished in Ind. Eng. Chem. 



248 H. W. GILLETT AND E. L. MACK. 

tons of Mo steel of the usual Mo content." The Bureau of 
IMines is therefore interested in Mo steel both from the point 
of view of preparedness and avoidance of dependence on for- 
eign raw materials and from that of development of a national 
mineral resource that is as yet so little used as to justify includ- 
ing Mo among the rarer elements despite the size of the deposits. 

Much work^^ has recently been done on Mo steels, almost all, 
save the pioneer work of Swinden that has been done by ob- 
servers not primarily interested in the sale of Mo, having been 
published in the last two or three years. When the Bureau 
started its work on Mo steels, very little data that was definitely 
free from possible bias was available. Now, however, there is 
such a mass of well agreeing data that there is little chance for 
argument as to the facts. 

The Bureau's objective in the work on Mo was, incidentally, to 
check up the outside data on ordinary tests, but primarily to get 
some idea of how far Mo can replace other alloying elements, and 
to secure data on the resistance of Mo steel to shock and fatigue, 
points of increasing importance to the engineer and on which 
strong claims of excellence have been made by advocates of Mo. 

For two years the work was carried on under a co-operative 
agreement with the Vanadium Corporation of America, producers 

■* Compare Moore, R. B., Molybdenum. Political and Commercial Control of the 
Mineral Resources of the World, Bur. Mines Mimeographed Report No. S of War 
Minerals Investigations Series, August 25, 1918. 

15 Bullens, D. K., Steel and its Heat-Treatment 354 (1916). 

Swinden, T. Carbon Molydenum Steels, Jour. Iron Steel Inst., Carn. Sch. Mem., 
3, 66 (1911). 

A study of the constitution of C-Mo Steels, Carn. Sch. Mem. 5, 100 (1913). 

Wills, C. H., U. S. Pats. 1,278,082; 1,288,345, Canadian Pat. 192,341 of Aug. 
26, 1919, British Pat. 150,343 of Aug. 24, 1920. 

Sargent, G. W., The Value of Mo Alloy Steels, Trans. Am. Soc. Steel Treat., 1, 
589 (1921). 

Cutter, J. D., Suggested Methods for Determining Comparative Efficiency of Certain 
Combinations of Alloy Steels, Trans. Am. Soc. Steel Treat, 1, 188 (1920). 

McKnight, C, Jr., A Discussion of Mo Steels, Trans. Am. Soc. Steel Treat, I, 288 
(1921). 

Schmid, H. M., Mo Steel and its Applications, Trans. Am. Soc. Steel Treat., 1, 300 
(1921); Chem. and Met. Eng. 24, 927 (1921); Iron Age, 107, 1,444 (1921). 

Hunter, A. H., Manufacture and Properties of Mo Steel, Iron Age, 107, 1,469 
(1921); Chem. and Met. Eng. 25, 21 (1921). . „ ^ „ 

Anon, Heat Treated Castings of Cr Mo Steel, Trans. Am. Soc. Steel Treat. 1, 
588 (1921); Iron Age., 107, 1,052 (1921). . , „ . , ^„ 

French H. J , Effect of Heat Treatment on Mechanical Properties of a C-Mo 
and a Cr-Mo Steel, Trans. Am. Soc. Steel Treat., 2, 769 (1922). 

Dawe, C. N., Cr-Mo Steel Applications frorn the Consumer's Point of view, 
Soc. Automotive Eng., Annual Meeting Jan., 1922. ., ,,, ,,„-,ox 

Mathews, J. A., Mo Steels, Trans. Am. Inst. Min. and Met. Eng., 47, 137 (1922), 
Iron Age, 107, 505 (1921). ^ . , ^ , 

Climax Molybdenum Co.. Booklet — Molybdenum Commercial Steels, 1919. 

Crucible Steel Co., Booklet— Al-Mo Steels, 1919. o. , -,. . 

Vanick, J. S., Properties of Cr-Mo and Cr-V Steels, Trans. Am. Soc. Steel Treat, 
3, 252 (1922). 



EXPERIMENTS WITH RARE ELEMENTS IN STEEL. 249 

of Mo. For the last six months it has been carried on by the 
Bureau alone, and it will take at least six months more to com- 
plete the time-consuming endurance tests which are the central 
point of the investigation. 

In the preparation of Mo steels, by adding ferromolybdenum 
to the charge at the beginning of the heat, the recovery was 
found to be quantitative and no segregation was found. 

The most important property of Mo in steel is the control 
it gives of the development by heat-treatment of the properties 
desired. Comparing C steels with alloy steels as a class, the 
carbon steels are not so readily brought over by quenching, to 
the metastable, hardened state. Carbon steels require drastic 
quenching with its attendant stresses and dangers, they do not 
harden throughout in large pieces, and if heated too high before 
quenching in order to increase the hardening effect, they de- 
teriorate on account of excessive grain growth. The introduc- 
tion of alloying elements, such as Mn or Ni, alone or in com- 
bination with Cr or V, makes the steel much more readily hard- 
ened, even in large pieces, and the evil effect of over-heating 
diminishes. The introduction of a sufficient quantity of the 
proper alloys makes the steel so sluggish that even cooling in 
the air produces a self-hardening or air-hardening steel. By 
proper adjustment of the alloy content and the carbon content, 
any gradation between a C steel that will not harden at all and 
an air-hardening steel can be made. 

The best classification of steels, which was made by Aitchison'* 
in his excellent book, is on the basis of the properties that can 
be developed in them, or, what is almost the same thing, their 
relative propensity toward hardening, rather than on chemical 
composition. 

From this point of view. Mo is — C excepted— the most active 
and potent element used in steel. The propensity toward harden- 
ing can be shown by varying the rate of cooling or by varying 
the maximum temperature to which the steel is heated, and cool- 
ing at a constant rate, since raising the initial temperature aids in 
suppressing the stable change and producing undercooling or 
hardening, much as increasing the cooling rate does. In either 

" Aitckison, L., Engineering Steels, Van Nostrand, 1921. 



250 



H. W. GILLETT AND E. L. MACK. 




S33iiD3(r 



EXPERIMENTS WITH RARE ELEMENTS IN STEEL. 25 1 

method the lowering and "spHtting" of the critical points on cool- 
ing will show the propensity toward hardening. 

Fig. 6 shows differential heating and cooling curves of steels 
of about 0.40 per cent C, 1.25 per cent Ni, 0.70 per cent Cr. 
No. 15 has higher C, but the comparison of the steels is not 
altered thereby. 

On either the plain Ni-Cr or the Ni-Cr-V steel, the critical 
point on cooling at the slow rate used (about 75 min. to cool to 
300° C.) is not appreciably altered (slightly lowered) by raising 
the maximum temperature from 775° to 900° C. But with the 
addition of 0.31 per cent AIo, cooling at the same rate from 
770° C, gives a weaker critical point at the normal temperature, 
and a new weak one starting about 525° C. and with a maximum 
at 450° C. At the upper point the austenite goes over to primary 
troostite, which at the ordinary rate of cooling immediately goes 
over to pearlite ; but some austenite is retained unchanged, which 
at the lower critical point goes over into martensite. This mar- 
tensite is not stable at the temperature at which it is formed, 
and in turn goes over to secondary troostite or sorbite on slow 
cooling. 

As the maximum temperature is raised, the upper critical 
point becomes slightly lowered and progressively weaker, and 
the lower point becomes stronger, till at 900° C. maximum tem- 
perature the upper point is wholly wiped out and the steel shows 
only the low critical point corresponding to the formation of 
martensite, i. e., is wholly air-hardening. The propensity toward 
hardening is so great that many Mo steels will harden throughout 
on oil-quenching in sizes which would not harden at the center 
on water-quenching without the Mo. 

This same effect is shown by Mo in all combinations. If we 
leave out the Ni and Cr and raise the Mo to say 0.75 per cent, we 
get a similar family of cooling curves. As we raise the C, the 
Mn or the Ni, it takes less Mo to shift the steel from the 
behavior of a plain C steel on cooling toward that of an air- 
hardening steel.- With combinations of Cr and ]\Io the effect 
of Mo is not quite so marked, but it is still evident. 

Whatever the composition of the steel in which it is used, the 
presence of Mo tends to make the steel require less drastic 
quenching and to make it harden to a greater depth on a given 



252 H. W. GILLETT AND E. L. MACK. 

quench. This slowing up of the transformation gives much 
better control over the hardening operation, and this control is 
given in good degree by quite small percentages of ]\Io, 0.20 
per cent Mo having a definite effect. If the steel is to be used in 
the normalized condition, the air-hardening properties may be a 
decided drawback. Even if the steel does not become difficult to 
machine, the normalized steel is not very good as to elastic 
limit, ductility or single-blow notched-bar test. When the Mo 
is over say 0.40 per cent and normalized, plain V or Cr-V steels 
appear more desirable than normalized Mo or Cr-Mo steels, 
unless tensile strength is the prime aim. Molybdenum steels 
•should be used in the heat-treated condition to secure the maxi- 
mum beneficial eftect. 

Vanadium does not, in itself, produce a strong tendency toward 
air-hardening. However, the greater hardening due to quench- 
ing from a higher temperature can safely be made use of in V 
steels, because of the marked ability of V to inhibit grain growth 
of austenite at temperatures that would give fatally coarse grain 
in C steel. j\Iost alloying elements have this property in some 
degree, and Mo shows it strongly, though the efifect is probably 
not quite so great as with V. 

Vanadium steels generally show a higher elastic ratio than 
other alloy steels. In this respect, ]\Io has very nearly the same 
effect as V. The individual good properties of both Mo and V 
are still in evidence when other alloying agents are present, and 
they may both be used together. For example, the addition of 
V to a Cr-Mo steel produces a steel of remarkable toughness.^^ 

The effect of Mo is shown not only in the behavior on quench- 
ing, but in tempering also. A hardened Mo steel does not soften 
on tempering with the facility of a similar steel without Mo. To 
bring the steel to a given strength or hardness, it has to be 
tempered at a higher temperature or for a longer time than one 
without Mo. Steels high in Mo, especially in the presence of a 
good deal of other alloying elements at first change in properties 
at a slow rate with increasing draw temperature, and more 
rapidly at very high draw temperatures so that at the highest 
draws it may require very accurate temperature control to get 

" See Sargent, G. W. he cil. p. 596. 

Crucible Steel Co. Booklet. Al-Mo Steels. 39 (1919). 



EXPERIMENTS WITH RARE ELEMENTS IN STEEL. 253 

the same results on consecutive draw heats. But, if the Mo 
content is not too high, so that the properties desired are obtained 
in the range of draw temperatures through which the properties 
change slowly (and this is the case with most commercial Mo 
steels) less accurate control is required and consecutive heats 
produce more uniform results than with most other alloy steels. 

The resistance to tempering shown by Mo steels holds promise 
for these steels for use at temperatures above normal, but no 
extended study of their properties at higher temperatures seems 
to have been made. Another advantage in the sluggish nature 
of a Mo steel is that the higher draw temperature for a given 
hardness or strength means a better release of quenching 
stresses. 

Table II gives some of the data secured on heat-treated r^Io and 
comparison steels. These figures are all on specimens heat 
treated in 1 inch diameter or less. Were larger specimens used, 
say 3-inch diameter, the depth-hardening properties of Mo would 
give the Mo steels an advantage that is not shown by the table. 

A cursory examination of the table will show that Mo has a 
real strengthening effect and that the heat-treated Mo steels 
combine good strength with good ductility and toughness. 

With 2.5 per cent Ni, 0.8 per cent Cr and 0.75 per cent jMo, 
one can get results of the same general order as with 3.5 per cent 
Ni, 1.5 per cent Cr. Cr-V and Cr-Mo steels each have nearly the 
same properties. On the other hand, i\Io finds its chief use as an 
addition together with Cr, Ni, or Ni-Cr. Quite good alloy steels, 
decidedly ahead of plain C steels, can be made with up to 1 per 
tent Mo, especially by increasing simultaneously the Mn per cent. 

From the results of a couple of Ni-Si plus Mo steels, given 
the 175° draw, the Bureau of Standards concludes^^ that these 
steels would be superior with the Mo omitted, while Johnson^^ 
secured good results in such steels with Mo, but says that it is 
not certain that the improved showing was due to the Mo. In 
the second series of Ni-Si steels made for the navy, one was 
included which contained Mo. This showed the normal effect of 
Mo in increasing the strength at high draw temperatures without, 
however, appreciably altering the ductility. This steel had rather 

•' Burgess, G. K., and Woodward, R. W., lec. cit. p 133. 
'8 Johnson, C. M., loc. cit. p. 501. 



254 



H. W. GILLETT AND E. L. MACK. 



"" fa 




Stanton 

test 

No. 

blows 


gsss S S ^ S S S o S S S s ^ ^ S 5 S S So oSSSS 

00 \C i-O c OC tT t^ r^ U-, u". O ""- ^ ""•'-'"• lt; O O ^C; ""- ^ LO ^ t^ \C lO 'I- "^ 


Reduc- 
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in 
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Ulti- 
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tensile 
in 

lono lb. 

sq.in. 


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O. 0Cr^C>^CNI^CCO\C3Cu--\Ct^C^O"~. (^-vCtv.OCVCvOOCvOOOCO'-t^ 

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Yield 

point* 

in 

lOon lb. 

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BrinncU 


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2 


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rN.rv.r-^.tv.\oooqocMCM^\o\co^. <^'-o'^u-5t^o\o^t>>o^oovD\o 
<Ddc>dddcJ-^"»-«'.-H'dcio'o'ddo'cddco'dc;ddc)dd 


w 


CM^CMf^OOOCrO\CiOCMOOO-^rM'*C\Cv'OCt^r-iOOrr>CM.— -^l-OO 
CMfO'^'^'^'^'-'^OrOTfco— iCMTl-ro-H^ — — -^^OCMrtCMf^rOcO'tj-CM 

d o' c; c c> CD d c d d c> d d d c" o' d © d o' d d d d d c © c5 d 


U 


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d 


.-Hrr)(M^(M'*>OvOOOr«.aNiO«-iOCMI^\Oa^OOO>Dt>.vOOOrHr<^CMvCrt 

-l-'3--*'0 '*l-li-<,-(-^-i--^-^u-;»-lr-t^r-lCMCMCMCM(M 



EXPERIMENTS WITH RARE ELEMENTS IX STEEL. 



255 



Table II. — Continued. 
Physical Data for Alloyed Steels. Normalised. 




* Steel No. 44 cooled in furnace with door open, t No test. 



too much Si to show best results from the addition of another 
hardening element. . . 

Some fairly good :^Io high speed steels have been made, and it is 
possible that they will be tamed and used some day. So far, the 
results are too erratic, and AIo does not appear to be a serious 
competitor of W for this purpose. 

On the single-blow notched bar Izod tests (on the standard 
round bar, V notch 0.25 mm. radius at base) and on Stanton 
repeated impact tests (5-lb. hammer, 2-in. fall, square notch, O.Od 
in. wide, 0.05 deep, 0.01 in. radius at corners) the ]Mo steels show 
properties similar to other alloy steels of their respective classes, 
when due consideration is given to the effect of tensile strength, 
C content and other variables outside of ^lo in these tests. (Our 
thanks are due to Mr. J. H. Nelson, of the Wyman Gordon Co., 
for making the Stanton and Izod tests). 

The repeated bending endurance tests, made on Upton-Lewis 
machines (kindly made available for our use by Sibley College, 
Cornell University) are still incomplete, although a large num- 
ber have been made. It has been claimed in technical and adver- 
tising literature that Mo steel is in a class by itself as to endurance 
against repeated or vibratory stresses. Similar claims have been 



256 H. \V. GILLETT AND E. L. MACK. 

made for a long time for V steel, and no text-book discussion 
of V is complete without the statement that V in steel enables 
steel to withstand vibratory stress. And in practice, it is found 
that both these steels do give good service under conditions of 
severe repeated stress. 

The claims for Mo steel against fatigue were largely based 
on the evident asumption that since Mo steel has a high 
ductility for a given tensile strength, the toughness must give 
good endurance. 

But the work of Moore-" and McAdam-^ has shown that the 
resistance to repeated bending, at least in sorbitic and pearlitic 
steels, is strictly proportional to the tensile strength, while the 
elastic limit, yield-point and ductility have no direct relationship 
to endurance. Published data of endurance tests on alloy steels 
are incomplete, but there are indications that any sound, clean 
steel is equivalent in endurance of any other sound, clean steel 
of the same tensile strength. 

Our work indicates that this relation between tensile strength 
and endurance limit is a good first approximation, at least for a 
pretty wide range of alloy steels. There are often greater devia- 
tions from this relationship in sister bars of the same steel than 
among different steels of widely different types. Slight dift'er- 
ences in surface finish or in the cleanliness of the steel make 
great differences in the results. The only place that we can see 
any effect of ductility is in very hard steels as compared to softer 
steels, the former being more sensitive to surface scratches or 
non-metallic inclusions. 

We are led to believe from our work that the cleanliness of a 
steel, its uniformity of composition and structure, and its freedom 
from internal stress have far more eft'ect on its life under repeated 
stress than its composition. The quahty of the steel has more to 
do with the endurance than the question of whether it is a C 
steel, a Mo steel or a V steel. 

Of course, if the comparison is made between, say a plain 
Cr and a Cr-Mo steel having received the same heat treatment, 
the one containing Mo will be superior, simply because it is 

'" Moore, H. F., and Konimers, J. B., An Investigation of the Fatigue of Metals, 
Univ. of 111., Bull. No. 8, 19, (1921), Eng. Expt. Sta., Bull. No. 124. 

" Mc.Adam, D. J., Jr., Endurance of Steel Under Repeated Stress, Chem. and 
Met. Eng., 25, 1,081 (1921). 



EXPERIMENTS WITH RARE ELEMENTS IN STEEL. 257 

Stronger for the same draw. There is probably one real advan- 
tage in Mo, in that a Mo steel of given strength requires a higher 
draw temperature than one without Mo, and hence internal 
stresses which quite certainly reduce endurance are more fully 
relieved,^^ As to V, it is probable that, although it is only added 
to steel for its alloying effect, its use makes for cleanliness in steel, 
because of its strong affinity for oxygen and nitrogen, and it is 
certain that since V and Mo are both rather expensive, the steel- 
maker normally will not put either into a heat of steel without 
taking particular pains with that heat. This psychological effect 
on the steelmaker probably causes these steels to be better made 
than the average steel, and hence they give better endurance and 
reliability in practice. 

We are comparing the endurance of different classes of sim- 
ilar heat-treated steels in which the variable alloying elements 
are Ce, Mo and V; the latter as a basis for the comparison. 
So far the steels containing Ce and therefore full of inclusions, 
fall down badly on the comparison, especially when in a very 
hard condition. In the grand average to date Mo steels are a trace 
ahead of V steels, but consideration of the data shows that this 
is due to one open-hearth Cr-V steel supplied by a commercial 
producer which shows up poorly on most heat treatments. The 
V and Mo steels made by the Bureau show equally good endur- 
ance at equal tensile strength. 

Hence, while the exaggerated claims for Mo steel in regard to 
endurance cannot be corroborated, it seems, nevertheless, true 
that a well-made Mo steel is at least as good in endurance as any 
other well-made steel. 

Abbott-" has summed up the situation in a few words. He 
says that there is no one type of alloy steel that resists fatigue 
better than any other, that there is no alloy steel which is 
markedly superior to all others, each alloy steel requiring its 
own particular heat treatment, and the choice of an alloy steel 
depends largely on the ease with which the necessary heat-treat- 
ment can be given it. He says that on this basis the outlook for 
more extensive use of Mo steel is good. 

-- Compare Aitchison, L., Engineering Steels, 204 (1921). 

=3 Abbott, R. R., The Heat Treatment of Automobile Steels, Iron Age, 106, 1,110 
(1920). 



258 DISCUSSION. 

Wood,^* basing his conclusions on wide experience with results 
in Liberty engines, says that Cr-Mo and Cr-V steels are 
equivalent. 

From every point of view it appears that Mo is an alloying 
element in steel, which in value stands with Ni, Cr, and V. 
Only inertia keeps it from wide use. Enough is known of Mo 
steel to make its good qualities evident. There is, of course, valid 
objection by steelmaker and user to adding another type of steel 
to the list instead of following the general trend of standardization 
and simplification. Since the first cost of Mo steel today is no 
more than that of any other alloy steel of equivalent properties, 
and its use is often attended with reduction in machining costs, it 
will undoubtedly be more widely employed. Tests to date on the 
use of U, B, Ti, Zr and Ce as alloying elements have not given con- 
sistently satisfactory results. In fact, in view of the non-metallic 
inclusions attendant on the use of all these except B, and of the 
eutectic formed with B, we feel that their use is more likely to be 
definitely harmful than definitely advantageous. 



DISCUSSION. 

H, W, GiLLETT : I would like to add a word that is not in my 
paper. The market quotations for steel bars show that it is not 
any more expensive to produce a given set of properties with 
molybdenum steel than with chrome-vanadium or nickel-chrome. 
Personally, I am much sold on molybdenum steel. I do not feel 
quite in the frame of mind of one advertisement I saw a couple 
of days ago, however, where a firm advertised: "Steel — Super- 
Steel — Molybdenum Steel !" Nevertheless, I think it is a valuable 
alloying element. 

Bradley Stoughton^: I think this j^aper of Dr. Gillett's is 
a valuable and interesting one. He has given us a lot of new 
light on two matters particularly. I refer to the question of 
segregation and sonims. By sonims I mean solid non-metallic 
impurities in steel. They may be anywhere from almost molecu- 

" Wood, H. F., Progress in Metallurgy of Alloy Steels, Amer. Drop Forger, Jan. 
1920, p. 25. 

• Consulting Engineer, New York City. 



EXPERIMENTS WITH RARE ELEMENTS IN STEELS. 259 

lar size up to particles that are plainly visible under the micro- 
scope. But whatever they are, they are common in almost all 
steel, and they make steel that is not clean. 

There are and always have been two grades of steel. There is 
good steel and super-excellent steel. For years there was only 
one type of super-excellent steel and that was crucible steel. The 
reason for that was freedom from segregation, freedom from 
gases and freedom from sonims. 

Now electric steel is attempting to invade the field of super- 
excellent steel. Whether it succeeds or not depends upon the 
amount of care and the amount of money that the electrical fur- 
nace people are willing to spend on the manufacture of their 
steel. They have not made their steel carefully enough. They 
have not observed precautions that should be observed to make 
steel free from segregation and sonims. 

At the present time, very good steel is made by the acid open 
hearth process, and you can get, by several processes, steel that 
is low in sulfur, low in phosphorus, low in gases and all other 
impurities, except sonims. The authors of this paper have studied 
really the question of sonims, and they have only scratched the 
field where we must have someone plow deep and harrow and 
till and cultivate the crop. That is no criticism of their paper. 
It is a good paper, but it only begins to scratch the field that needs 
to be greatly worked. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 5, 1923, President Schlueder- 
bcrg in the Chair. 



SOME EFFECTS OF ZIRCONIUM IN STEEL 

By F. M. Becket'. 

Abstract. 
This paper refers briefly to the commercial development of 
various alloys of zirconium. Certain specific effects of zirconium 
in steel are described as determined in an extensive series of 
experiments. Outstanding eft'ects include the ability of zirconium 
to eliminate oxygen, nitrogen and sulfur ; the remarkable effect 
of zirconium in overcoming red-shortness in high sulfur steels ; 
and the striking improvement in physical properties of plain 
carbon steels brought about by the presence of zirconium in rela- 
tively small proportions. 



The title of this paper purposely expresses considerable limita- 
tion and implies brevity. At this time the principal object is to 
describe some of the specific eft'ects of zirconium, as determined 
in the course of an investigation which has involved 350 experi- 
mental heats of steel made for this particular purpose. It is 
intended that a much more detailed discussion of the results will 
be presented in the near future, including descriptions of the 
procedures of the steel making, the physical testing, the metallo- 
graphic studies and other phases of the work. 

Numerous experiments on the reduction of zirconium ores and 
the preparation of zirconium alloys were conducted at the 
Niagara Falls plant of the Electro ^Metallurgical Co. during the 
period of a few years immediately preceding the entry of United 
States into the world war. These endeavors confirmed in a gen- 
eral way the published data relating to the properties of some 
of the zirconium compounds ; but, more particularly, they devel- 

1 Chief Metallurgist, Union Carbide Co., New York City. 

261 



262 F. M. BECKET. 

oped a few important, unforeseen results, which enabled the 
author to relate much more closely than he had previously found 
possible the properties of zirconium and certain zirconium com- 
pounds to the properties of other more thoroughly understood 
refractory materials. 

Early in the year 1918, having been influenced by apparently 
authentic reports concerning the use by Germany of remarkable 
ordnance steels containing zirconium — reports which were later 
considered groundless, if the author has been correctly informed — 
the War Industries Board decided upon an intensive program of 
experimentation with zirconium in steel for light armor, the 
direct object being the earliest possible large scale production, 
and the Electro Metallurgical Co. was requested to furnish zir- 
conium alloys with this end in view. A vast amount of energy 
was then expended in the way of comparatively large scale experi- 
mentation on the production of a variety of zirconium alloys, 
and the Ford i\Iotor Co. assiduously attacked the problem of 
zirconium steel with high ballistic qualities. At the date of the 
armistice considerable tonnages of zirconium-silicon alloy were 
being shipped to designated steel companies for the purpose of 
large scale manufacture, this particular alloy having been selected 
as the most efficacious after trial heats with many other zirconium 
alloys. As a result of the armistice, the major portion of the 
alloy in these shipments did not find its way into the nickel-silicon 
steel for which it was intended. However, this additional experi- 
mentation on the production of zirconium alloys brought still 
more forcibly to the mind of the author certain peculiarities of 
zirconium. 

The United States Navy also became interested in zirconium 
steels, and requested the co-operation of the Bureau of Mines 
and of the Bureau of Standards, According to H. W. Gillett 
and E. L. Mack, in Bulletin 199 of the Bureau of Mines, 1922, 
entitled "Experimental Production of Alloy Steels," production 
heats of a series of zirconium and other similar steels began in 
September, 1918. In this Bulletin are described fully the methods 
involved in making the experimental heats (50 lb.) of zirconium 
steel, and valuable information is contributed concerning the 
recoveries of zirconium obtained from several different zirconium 
alloys. Technologic Paper, No. 207, of the Bureau of Standards, 



some; effects of zirconium in steel. 263 

1922, entitled "Manufacture and Properties of Steel Plates Con- 
taining Zirconium and Other Alloys," by G. K. Burgess and 
R. W. Woodward, reports in detail the properties of the zirco- 
nium steels made by the Bureau of Mines. It is the author's 
understanding that as part of the zirconium phase of the investiga- 
tions reported in the Governmental papers just mentioned, it was 
greatly desired to determine whether the exceptional properties 
of some of the steels made under the direction of the Ford Motor 
Co. during the summer of 1918 could be properly attributed to 
zirconium. The conclusions drawn by the authors of Technologic 
Paper, No. 207, are to the general effect that no particular 
enhancement of desirable physical characteristics are to be 
ascribed to zirconium, at least in the types of steel tested, and that 
the effects of this addition agent may be detrimental. 

The foregoing statements have been made to explain that a 
tenacious enthusiasm for zirconium was the result of information 
acquired during the smelting of zirconium-bearing materials, 
the production of various alloys of zirconium, and the refining of 
some of these alloys. So impressed was the author in respect to 
certain properties of zirconium, that an extensive program of 
experimentation on zirconium-treated steels was instituted, and 
has since been continuously maintained with increasing encourage- 
ment. This program was launched with knowledge of the decid- 
edly skeptical attitude the steel fraternity had acquired concern- 
ing the value of zirconium additions to steel in general, and in 
particular the role of this element in the excellent steels that had 
occasionally been produced by the Ford jNIotor Co. 

The practice followed in the steel heats of the present investi- 
gation has involved in the great majority of cases the melting 
of a 200 to 350-lb. charge of cold scrap-steel in a basic-lined 
electric furnace. Duplicate or triplicate ladles have been tapped 
from each heat in order to permit of a reliable comparison 
between the effect of the zirconium alloy addition and that of an 
equivalent addition of ordinary ferro-silicon. Whether rolled 
or forged, the ingots from any given heat have been treated 
identically so far as was possible during hot working, and all 
annealing, normalizing, and heat treating operations on the 
finished product have been likewise conducted so as to insure 



264 F. M. BECKET. 

Strictly comparable results. The rolling and forging of the ingots 
have been performed under ordinary mill conditions by experi- 
enced operators. 

ZIRCONIUM AS A DEOXIDIZER AND SCAVENGER. 

Zirconium has a greater affinity for oxygen than has silicon, and 
due to this fact increased recoveries of silicon in the finished 
steel are obtained by the use of zirconium-silicon alloys. This 
greater recover^' of silicon is quite marked when an alloy of 35 
per cent zirconium is employed. For example, in a series of 40 
heats of basic electric furnace steel an average silicon recovery 
of 98 per cent was realized, as compared with a recovery of 84 
per cent for ordinary ferro-silicon added under identical condi- 
tions and in equivalent percentages of added silicon to duplicate 
ladles. This particular series resulted in a 56 per cent average 
recovery of zirconium, ladle additions of 0.15 per cent zirconium 
having been made in all cases. 

The rate of the reducing action of zirconium on the impurities 
present in molten steel is not only more rapid than that of silicon, 
but zirconium is the more efficacious in removing the final traces 
of oxygen and nitrogen. This scavenging power of zirconium 
is demonstrated in the partial or complete elimination of the 
banded structure in rolled or forged products, and in an increased 
rate of coagulation of emulsified slag. Zirconium-treated steels 
possess a cleanness which appears to be the result of a far more 
deep-seated action than characterizes the well-known deoxidizing 
and scavenging agents. There seems to be abundant experimental 
evidence to justify this assertion, but the relative brevity of this 
paper precludes a discussion of this side of the subject. 

Brief reference may be made to the analytical evidence relating 
to the deoxidizing power of zirconium. By means of new 
methods of analysis developed by the Bureau of Standards for 
the determination of oxygen and nitrogen in steel, reliable data 
have been obtained in co-operation with the Bureau on four heats 
of steel treated with zirconium-silicon (0.15 per cent added Zr) 
and with ferro-silicon in duplicate ladles. The analyses show 
that the zirconium treatment eliminated from 12 to 84 per cent 
of the total oxygen present in the steel (including oxygen as 



SOME EFFECTS OF ZIRCONIUM IN STEEL. 265 

FeO, MnO, SiOo, ZrOg and silicates), the average being 54 per 
cent. Or, expressed in another manner, the zirconium-treated 
Steels showed a reduction in oxygen content of 54 per cent as 
compared with the steels treated with ordinary ferro-silicon. 
Analyses on another similar series of 4 heats gave 0.0035 per cent 
nitride nitrogen for the zirconium-treated steels as compared 
with 0.0072 per cent for the ferro-silicon-treated steels. 

No indication of the occurrence of inclusions of zirconium 
oxide has been observed in the course of this investigation. All 
the evidence obtained points to the conclusion that oxidized zir- 
conium forms with silica and oxide of manganese a fusible slag, 
which quickly rises to the surface of the ladle. Analyses of ladle 
slags have confirmed this conclusion. 

Minute, yellow, cubic crystals of zirconium nitride are gener- 
ally observed in steels treated with zirconium in excess of approx- 
imately 0.10 per cent. They are strictly limited in number and 
represent that residuum of the nitrogen content of the steel which 
was fixed by zirconium, but not slagged off prior to solidification. 
These crystals as such do not exert a harmful effect on the steel ; 
for instance, they were present in their usual amount in the heat- 
treated steels whose properties are mentioned later in this paper. 

Fatigue tests to failure under rotary alternating stress have been 
made on 23 heats treated in duplicate ladles with zirconium-ferro- 
silicon (0.04 per cent added Zr) and 50 per cent ferro-silicon. 
The average effect of 0.04 per cent added zirconium has been an 
increase in the endurance limit by 1,125 lb. per sq. in. This is 
particularly significant in view of the recognized detrimental 
effect of non-metallic inclusions upon endurance limit. 

ZIRCONIUM AND SULFUR. 

When zirconium is added to steel in excess of approximately 
0.15 per cent, this element assumes a new role by chemically com- 
bining with sulfur to form an acid-insoluble compound not de- 
tected by means of the ordinary evolution method of analysis, 
and under any given set of operating conditions a linear relation 
exists between the percentage of sulfur thus fixed and the amount 
by which the added zirconium exceeds 0.15 per cent. It has been 
reasonably well established that for basic practice when the zir- 
conium-silicon alloy is added in the ladle, every part by weight of 

18 



266 F. M. BECKET. 

zirconium added in excess of 0.15 per cent fixes 0.10 part by 
weight of sulfur as an acid-insoluble, zirconium-sulfur compound. 
This chemical combination proceeds in as quantitative a degree 
when the steel contains normal sulfur and manganese contents, 
as it does in those instances where the steel is sufficiently high in 
sulfur and low in manganese to give rise to an appreciable propor- 
tion of iron sulfide. In other words, zirconium has a greater 
affinity for sulfur than has manganese. The difference here in 
affinity favorable to zirconium is probably greater than the cor- 
responding difference between manganese and iron. 

A 5-ton acid open-hearth heat and a 10-ton basic electric fur- 
nace heat may be cited as examples of the influence of zirconium 
on sulfur as determined by the evolution method. In the former 
case an addition of 0.27 per cent zirconium as silicon-zirconium 
lowered the percentage of sulfur from an initial value of 0.040 
per cent to a final value of 0.025 per cent ; in the latter a 0.22 per 
cent addition of zirconium diminished the sulfur from 0.020 to 
0.009 per cent, leaving 0.15 per cent zirconium in the finished 
product. 

Under favorable conditions the zirconium-sulfur compound 
may be actually eliminated from the steel by fairly heavy additions 
of zirconium-sihcon alloy. Steels containing 0.08 per cent total 
sulfur have been reduced by ladle additions to a total sulfur of 
0.048 per cent, and a corresponding sulfur content of 0.037 per 
cent as determined by the evolution method. Actual desulfuriza- 
tion by zirconium is a field more limited and much less important 
commercially than the field covered by the effect of zirconium on 
the hot-rolling qualities of high sulfur steels now to be described. 

In order to obtain the full beneficial effect upon hot-rolling 
properties, the zirconium alloy need be added only in amount 
sufficient to eliminate the iron sulfide constituent responsible for 
red-shortness. Ingots containing 0.185-0.200 per cent sulfur and 
only 0.15 per cent manganese have been rolled to plate and sheet 
free from cracks and seams when the steel had been treated with 
0.22 per cent Zr. With steels containing sulfur up to 260- 
0.290 per cent similar results have been obtained by the addition 
of 0.43 per cent Zr. The untreated ingots of these steels have 
broken to pieces in every case on their first pass through the rolls. 



SOME EFFECTS OF ZIRCONIUM IN STEEL. 



267 



ZIRCONIUM IN HEAT-TREATED STEELS. 

The beneficial effect of small additions of zirconium is strik- 
ingly demonstrated in the case of heat-treated, ordinary carbon 
Steels, To illustrate, a heat of 0.70 per cent carbon steel was 
treated in one ladle with 0.15 per cent zirconium as a zirconium- 
silicon alloy, and in the other ladle with an equivalent amount of 
ordinary ferro-silicon. After forging the ingots to one-inch round 
bars the test data recorded in Table I were obtained on the steels 
quenched from 825° C. in water and drawn at the temperatures 
indicated. Standard S. A. E. specification for a much used nickel- 
chromium steel (2.75 to 3.25 per cent Ni ; 0.60 to 0.95 per cent 
Cr) are also tabulated for the purpose of comparison. 



Table I. 



0.70 per cent C 
0.15 per cent Zr 



Drawing Temperature 375° C. 

Per cent Elongation 8.3 

Per cent Reduction of Area.. 23.3 

Yield Point 185.952 

Ultimate Strength 227,203 _ 

Izod Number 7.5 

Brinnell Hardness 414 

Drawing Temperature 412° C. 

Per cent Elongation 12.7 

Per cent Reduction of Area.. 45.8 

Yield Point 172,620 

Ultimate Strength 198,828 

Izod Number 14.8 

Brinnell Hardness 407 



0.70 per cent C 
without Zr. 



375° C. 
5.2 
6.6 
128.125 
197,800 
7.5 
433 

412° C. 
7.5 
22.9 
180.180 
207,144 
10.5 
418 



S. A. E. 

3450 Ni-Cr 



427° C. 
12.5 
51.0 
175,000 
200,000 



It may be observed from Table I that ordinary carbon steels 
in which a small percentage of zirconium has been incorporated 
may be made to possess by suitable heat-treatment physical char- 
acteristics approaching those of the highest grade, heat-treated 
alloy steels. 

Additional experimentation has demonstrated that the proper- 
ties of a number of the well-known alloy steels may be improved 
through the use of zirconium, and also that by zirconium treat- 
ment it is sometimes possible to use advantageously the ordinary 
alloying elements in less than normal proportions. 



268 DISCUSSION. 

The author does not consider as relevant matter for this paper 
a discussion of the commercial aspects of zirconium in the manu- 
facture of steel, nor does he wish to engage in concrete prognosti- 
cations. Therefore it must suffice here to state that several steel 
companies to whom zirconium alloys were introduced have taken 
advantage regularly during the past two or three years of the 
excellent scavenging properties of zirconium. The effects of 
zirconium on sulfur and in heat-treated steels have been drawn 
to the attention of a few steel manufacturers only within a com- 
paratively recent period. 

However, there appears to be reasonable justification for the 
optimistic comment in conclusion, that in consideration of the 
specific effects herein mentioned and the experimental intimation 
of other effects now awaiting recognition, zirconium will probably 
contribute its fair share toward the progress of civilization through 
assistance to the steel and other metal industries. 

The author acknowledges the co-operation of his associates, 
Alexander L. Feild, J. H. Critchett, and J. A. Holladay. ]\Ir. 
Feild has contributed many valuable suggestions, and he has been 
throughout in immediate charge of the experimental steel manu- 
facture and laboratory testing, I\Ir. Critchett, by way of sugges- 
tion, has rendered much assistance, especially in connection with 
the manufacture of zirconium alloys ; and Mr. Holladay deserves 
much credit for original work on the quantitative determination 
of zirconium in ores and steels, and for his supervision of the 
analytical work involved in this investigation. 



DISCUSSION. 

E. F. CoNE^ : I can not refrain from saying that I think this 
Society is unusually fortunate in hearing what seems to me to 
be an epoch-making presentation of a subject that is, particularly 
in the future, going to be extremely important, especially with 
reference to the question of sulfur in rolling, and other points of 
equal importance. 

H. W. GiLLETT- : Have you data on the ductile properties on 
test pieces taken transversely instead of longitudinally? The 

1 Assoc. Editor, Iron Age, New York. 
» U. S. Bureau of Mines, Ithaca, N. Y. 



SOME EFFECTS OF ZIRCONIUM IN STEEL. 269 

difference in ductility really ought to show up more strikingly 
in this. 

F. M. Becket: These particular tests did not involve trans- 
verse sections. In other work, however, transverse testing has 
brought out directly the point you mention, and the effect of 
zirconium on the transverse properties has been rather marked in 
improvement. 

H. W. GiLLETT : That seems to indicate a cleaner steel when 
the transverse properties are good. 

E. F. Cone : What is the composition of these silicon-zirconium 
alloys you use? 

F. ^l. Becket : The composition of the alloys used both com- 
mercially and in this experimental work varies considerably, ac- 
cording'to just what was attempted— the class of steel it was 
desired to produce. 

Naturally, with a silicon-zirconium alloy, you are limited by 
the silicon content desired in the finished product. In cases of 
small additions of zirconium, it has been used pretty largely as an 
alloy containing approximately 10 per cent zirconium and 40 to 
75 per cent silicon. When it has been desired to introduce con- 
siderable zirconium in relation to the proportion of silicon in- 
troduced, an alloy of 35 to 38 per cent of zirconium and 50 to 55 
per cent silicon has been employed. 

H. W. GillETT: At still higher temperatures is there the same 
improvement in ductility? 

F M. Becket: Up to the moment, the improvement at higher 
drawing temperatures has not been so marked. It follows fairly 
well the characteristics of your nickel-chrome and other alloy 
steels, but I do not think the effect is so forcibly brought out as 
at temperatures referred to here. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 5, 1923, Dr. F. M. Becket in 
the Chair. 



INHERENT EFFECT OF ALLOYING ELEMENTS IN STEEL.' 

By B. D. Saklatwalla.2 

Abstract. 
The importance of the effect of alloying elements on the purely 
physical changes occurring among the constituents of steel is 
brought out. Stress is laid on the study of the physical condi- 
tions and their alterations by alloying elements, during the period 
of solidification. Attention is drawn to the importance of the 
effect of alloying elements on surface tension of the solidifying 
constituents. The idea is expressed of the possibility of coordina- 
tion and equivalence among alloying elements based on the periodic 
system, especially referring to atomic volume. 



Steel at the ordinary temperature is a heterogeneous con- 
glomerate of various crystalline constituents cemented together by 
the intervention, betv^een the crystal faces, of a medium existing 
in an indefinitely knov^^n physical state. The composition, physical 
structure, and relative proportions of these constituents are gov- 
erned not only by their chemistry, but also by the thermal life- 
history of the metal. The different phases are in the main made 
up of a metallic (ferritic) and a carbide (cementitic) constituent. 
Oviring to this heterogeneity, it is apparent that the physical forces, 
not only those at play in the individual components, but also those 
existing between the phases, will be of greater importance, from 
an engineering standpoint, than the chemical composition. Un- 
doubtedly through change in the chemical constitution of the 
components, as a means to an end, the physical changes are 
brought about. 

If, thus, to the ordinary constituents, consisting of metallic 

' Manuscript received January 30, 1923. 

» Gen. Supt. Vanadium Corporation of America, Bridgeville, Penna. 

271 



272 B. D. SAKLATWALLA. 

iron and an iron carbide, other elements are added, changes in 
the physical relations of these constituents will take place. The 
influences exerted by these elements constitute the metallurgy of 
alloy steels. The purpose of this paper is to survey such influ- 
ences on the physical relations of the constituents, and to direct 
attention to their study from a physico-chemical standpoint, 
devoting special attention to the period immediately preceding 
solidification of the steel, an interval in its life-history hitherto 
rather neglected. 

The remarkable properties conferred by carbon upon iron, 
making it steel, are due to the physico-chemical interactions 
between iron carbide and iron. A wide range of physical prop- 
erties suitable for particular engineering problems are obtainable 
from the same chemical composition of the metal by merely vary- 
ing the physical heat treatment. A plain carbon steel can be made 
exceedingly brittle and glass hard by quenching in cold water 
from a high temperature, or made ductile and malleable by 
allowing it to cool gradually from the same temperature. The 
discovery that additions of other metallic elements influence 
these changes and produce different results has been more or 
less of an accidental nature, and the development of alloy steel 
metallurgy has been more or less empirical. 

The constantly increasing number of alloy steels brought out 
in commerce makes it opportune to establish some scientific basis 
for the relative influence of the several elements depending on 
some equivalence in physical properties among them. Undoubt- 
edly some such equivalence of the elements exists, as several 
chemically different alloys can be made to produce steels of more 
or less similar physical properties under a divergence of heat- 
treatment. In order to investigate systematically the influence 
of these elements on the properties of the steel components, it 
seems logical to start such study at a period prior to the solidifi- 
cation of the metal. The physico-chemical activity of the con- 
stituents, and the change suffered by the addition of alloying 
elements, will be more pronounced, and less influenced by 
extraneous physical conditions, in the liquid, or during the solidi- 
fying, rather than in the final solid state. It will not be an exag- 
geration to assert that such a study of the inherent influence of 
alloying elements has been greatly neglected. 



EFFECT OF ALLOYING ELEMENTS IN STEEL. 273 

The splendid work of Bakhuis Roozeboom, Willard Gibbs, and 
others, has given us wonderful insight into the phenomena of 
solidification from the standpoint of thermo-dynamics and chem- 
ical constitution. We have applied these principles to the study 
of steels, and have been able to chart the solidifying phenomena 
and establish thermal analysis. We are thus in position to picture 
the constitution of the components in steel and further verify 
our picture by the aid of the microscope. It does not appear 
sufficient, however, to know the presence of these constituents 
and their chemical nature, without being able to correlate scien- 
tifically their chemical composition to their physical properties, 
and the changes occurring during their solidification to the 
engineering properties of the solidified steel. 

The inherent physical effects of chemical elements undoubt- 
edly start in the liquid stage, and, as the physical properties of 
the liquid from which crystallization takes place determine to a 
great extent the properties of the crystallized solid, the influence 
of the alloying elements should be studied in relation to the 
physical changes occurring prior to or during solidification. 
While undoubtedly, by the proper thermal treatment, much can 
be achieved in solid steel, yet it will be right to assert that the 
inherent characteristics of the steel are defined up to solidification 
in the ingot stage, and that all later thermal manipulations are of 
secondary importance. 

Solidification in a metallic alloy such as steel occurs selectively 
during an interval, the crystal growth starting from several 
nuclei in the melt. According to Quincke, a separation of the 
melt in two liquid phases takes place, the one in very much 
smaller quantity, the "oily" phase, forming cell walls for the 
other, the whole forming a "foam structure" with several points 
or nuclei for crystal growth. The application of X-ray analysis 
to crystal structure has shown us that the atoms of the crystals 
are arranged in definite characteristic space lattices in contra 
distinction to an indefinite arrangement in a liquid. 

Among the immeasurably large number of atoms of the liquid 
melt there will be some which will chance to have an arrange- 
ment corresponding to the space lattice arrangement of the solid 
crystals, or closely approaching it. We can readily see that such 
atoms will selectively assume the solid state ahead of the others, 

19 



274 ^- °- SAKLAT WALLA. 

and hence act as nuclei for crystal growth. Solidification from 
these nuclei will proceed, at the same time continuously dimin- 
ishing the quantity of the molten mother magma, until the amount 
of liquid, or the spaces left between the grown crystals, will be so 
small as not to allow further crystallization. This residual 
material will therefore fill up the capillary interstices between the 
crystals forming the so-called "intercrystalline cement medium." 

As to the exact nature of this medium there is considerable 
uncertainty. On account of it not following the crystallization of 
the first successive solidifying part of the melt, it has been com- 
monly called "amorphous." Recent observations with the X-ray 
spectograph on the amorphous metals would lead us to assume 
the presence of extremely fine crystal bodies combined with 
colloids in this "intercrystalline medium." Its remarkable prop- 
erties can be explained more satisfactorily on this assumption 
than on that of it being "amorphous." Owing to the importance 
of this medium from an engineering standpoint, it deserves 
further close study from the standpoint of colloid phenomena 
and X-ray analysis. 

The crystallization from nuclei and the growth of individual 
crystals will depend on the chemical composition of the melt, its 
degree of under-cooling, heat conductivity and diffusion capa- 
bility of the resulting crystals, etc. In these several factors, the 
presence of other alloying elements in the melt will exert a great 
influence on the progress of crystallization. For instance, slight 
impurities in the melt have been found to check the velocity of 
crystallization. The impurity adsorbs on the surface of the 
growing crystal, thus checking the velocity of its growth. If the 
adsorption on the different faces of the crystal is of a difterent 
degree, the crystallization velocity will be different in different 
directions, and consequently the soHdified crystal can be altered 
completely, for instance, from a polygonal to a dendritic form. 
Hence we can readily see that the presence of a small amount of 
another element in liquid steel can materially influence the size 
and shape of the primary crystals and alter the structure in the 
solidified steel. We are all aware of the importance of the 
primary ingot structure in engineering practice. 

Another property of growing crystals is that they eject any 
impurities to the surface of the crystal. The presence of another 



EFFECT OF ALLOYING ELEMENTS IN STEEL. 275 

element may alter the solubility of such impurity in the crystal 
and consequently influence the degree of its ejection. This 
ejection brings such impurities present, not only to the surface 
of the crystal, but into the "intercrystalline cementing medium." 
Thus, the presence of another alloying element may appreciably 
alter the amount of such impurity in this medium, and hence 
influence in a marked manner, in the finished steel, those physical 
properties which are a function of the "intercrystalline medium," 
such as elastic and endurance limits. 

Another influence of the ejection of foreign elements by grow- 
ing crystals can be seen in the case of non-corrosive steel alloys. 
It appears remarkable that the non-corrosiveness is brought about 
when a definite sharply recognized percentage of the alloying 
element is present. For example, 10 to 14 per cent chrome steel 
may be cited. This phenomenon is probably due to the fact 
that the growing crystal is capable of keeping in solution a 
certain percentage of the element, and starts ejecting it to its 
surface after this saturation is reached. The surface of the 
crystal can thus have a high percentage of the element requisite 
to give it the necessary protection against corrosion. 

Also in connection with other physical properties we are aware 
that the percentage of the alloying element has to be beyond a 
certain range. As examples may be cited 3.5 per cent nickel 
steel and 12 per cent manganese steel. The influences of these 
percentages can probably be similarly explained on the basis of 
ejection of these elements to the surface by the growing crystals, 
thus altering their surface properties of adhesion, etc., also intro- 
ducing a necessary amount into the "intercrystalline cement," 
altering its properties. From this standpoint it is also apparent 
why the presence of non-metallics in the fluid steel exerts such 
dastardly pernicious effect on the physical properties of the 
solidified metal. They not only influence the process of crystal- 
lization, but through ejection get disseminated in the vital con- 
stituents of the steel. 

Whether we agree with Quincke on the separation of two 
liquid phases prior to solidification, or believe in crystallization 
growing from the nuclei only, it is easy to see that the surface 
tension, with its dependent properties, of the molten magma will 
be of extremely great importance. Considerable work has been 



276 B. D. SAKLATWALLA. 

done on measurements of surface tension of liquid metals by 
several different methods. It has also been assumed, since the 
property of surface tension of a liquid depends so intimately on 
the cohesion of the molecules, and since the properties of liquids 
and solids show signs of continuity in the two phases, that some 
relation exists between the surface tension of the fluid metal and 
cohesion and tenacity in the solidified state. 

Also in studying liquids definite relations of other physical prop- 
erties to surface tension have been established. As such prop- 
erties of the liquids may be mentioned: molecular volume, com- 
pressibility, coefficient of thermal expansion, vapor pressure and 
solubility. Transferring these correlation of properties to the 
solid state, we find the important relation of surface tension to 
the factors which we generally term "hardness." Also we are 
aware from experimental data that "hardness" more than any 
other physical property forms a criterion for the endurance limit. 
Hence we see the importance of a study of the surface tension 
qualifications of a metal in the liquid state, and the influence of 
foreign elements on the surface tension in order to arrive at 
engineering merits after solidification. 

It is easy to understand that a property, so inherently a func- 
tion of the molecule itself as surface tension, should be ver}' 
sensitive to the presence of a foreign element molecule. Mole- 
cular forces of cohesion naturally act with greater energy between 
two unlike than like molecules. Consequently the presence of a 
foreign molecule will increase the cohesive forces. This increase 
can be of such magnitude as to constitute chemical affinity, and 
bring about a chemical combination of the metallic elements, 
forming inter-metallic compounds. It can be of lesser intensity, 
constituting physical action only, bringing about an inter-atomic 
rearrangement with a decrease of the total volume, increasing 
hardness. 

It is our practical experience that the hardness of a metal is 
generally increased by the addition of another metal to it. Also 
the properties and nature of solid solutions find an explanation 
in the intermolecular cohesive forces dependent on surface 
tension. Further, the modern ideas of allotropy seem to be 
finding explanation in the different cohesive forces in the atoms 
causing the presence of physically different but chemically 



EFFECT OF ALLOYING ELEMENTS IN STEEL. 277 

identical matter, the differing atoms being capable of interaction 
on one another. If we assume such explanation for the critical 
points in iron, we can readily understand how the presence of 
foreign molecules will change cohesive forces, and exert an 
influence on these points, which, in turn, will alter the reactions 
depending on these points, such as thermal reactions during heat 
treatment. Herein we can find an explanation of the great sus- 
ceptibilit}' of alloy steels for thermal treatment. 

Another influence, important from a practical standpoint, 
which alloying elements can exert is their influence on the non- 
metallic impurities in steel. The viscosity and surface tension of 
the melt can be altered by the alloying elements to allow a better 
mechanical separation, or the diffusion capability of the melt 
can be influenced so as to hinder or accelerate segregation of the 
non-metallics. It is also probable that slight additions of elements 
can greatly influence the colloidal properties of the non-metallics, 
inasmuch as their presence can bring about a flocculation or dis- 
persion of the impurities, rendering their effect less harmful. 

In the above considerations we have enumerated the effects 
brought about by the presence of alloying elements from a 
physical standpoint, without entering into any considerations of 
a purely chemical nature. In the introductory remarks we have 
hinted at chemical equivalence of the alloying elements. Un- 
doubtedly the principle of periodicity among elements as initiated 
by Wedeleeff, and expounded by Lothar Meyer, Crookes and 
others, which has given us such wonderful insight into the 
workings of pure chemistry, can be applied, with modifications in 
light of our newer knowledge of atomic structure, to metallurgy. 
If the elements are arranged as a function of atomic weight to 
atomic volume, or of atomic number to atomic volume, they form 
a series of connected curves, each one representing a group of 
elements and consisting of an ascending and descending branch. 
The properties of the elements so arranged seem to bear marked 
relation to their neighbors on the same curve. For instance, the 
melting points, hardness, ductility and brittleness, electronic prop- 
erties, surface tension, seem to be coordinated by these curves. 
It appears from this that the atomic volume, as an inherent char- 
acteristic of the atom, more than any other property is of para- 



278 B. D. SAKLATWALLA. 

mount importance. It undoubtedly is the criterion of the physical 
qualifications of material. 

In light of our present knowledge of the structure of the atom 
we can see that the atomic volume will be made up, not only of the 
masses of the electronic constituents, but also the intra-electronic 
spaces and the intra-atomic spaces. The action between atoms is 
known to be dependent on their relative arrangements in space 
lattices, and as these are brought about by forces acting over 
intra-atomic spaces we can readily see why the atomic volume 
should be a criterion of these changes. In this arrangement, 
according to atomic volume, it is remarkable that the steel alloy- 
ing elements group themselves close together. Attempts at gen- 
eralization among these elements have been made, such as the 
theory put forward by Osmond that elements with greater atomic 
volumes than that of iron tend to raise and those with atomic 
volumes less than that of iron tend to lower the transformation 
points, Arg, Arg, and Ar^. Also the elements producing marked 
effects in steel, possess high melting points, a characteristic also 
dependent on atomic volume. 

In practical application of these considerations extreme caution 
should be used, as the formation and presence of definitely formed 
chemical molecules in place of the individual atoms introduce a 
new phase in the chemico-physical equilibrium. In such cases we 
are confronted not with atomic but with molecular volumes, and 
the effect exerted by the addition of the element is that of the 
compound formed and not the element itself. 

In the absence of definite theoretical knowledge from a physico- 
chemical standpoint, we are obliged to judge the merits of alloy- 
ing elements from the results achieved by them. Undoubtedly 
the use of alloying elements has wonderfully advanced our 
engineering practice in steel construction. The role of these 
elements has sometimes been minimized with the argument that 
their presence only retards or accelerates the thermal changes 
bringing about refinement of structure. It is not beyond the pale 
of possibility that similar refinement can be brought about by 
other and perhaps purely physical means. Until such time, how- 
ever, we can not get away from the fact that alloying elements in 
steel have served indirectly as a means to an end to bring about 



EFFECT OF ALIvOYING ELEMENTS IN STEEL. 279 

these physical conditions. Have they not then fully and justifiably 
played the part credited to them ? 

As to the merits of the different elements it appears that each 
one has a definite role assigned to it to bring out more pro- 
nouncedly than the rest, certain definite physical characteristics 
in the steel. The sole criterion of the accomplishment of these 
characteristics remains today, service. Let us hope that more 
scientific study of the role of alloying elements in steel will not 
only give us insight into the workings of the alloying elements, 
but help to bring out newer types and compositions of steels, thus 
advancing not only the art of metallurgy, but the hopes and 
aspirations of our rapidly striding civilization. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 3, 1923, G. B. Hogaboom in 
the Chair. 



NOTES ON THE METALLURGY OF LEAD VANADATES.' 

By Will Baughman.^ 

LEAD VANADATE ORES OF THE SOUTHWESTERN UNITED STATES. 

Vanadium is widely distributed throughout the arid regions 
of Cahfornia, Arizona, Xew Mexico and Nevada. The prin- 
cipal minerals are vanadinite, descloizite and cupro-descloizite. 
Minor amounts of psittacinite, volborthite, eosite, endlichite, 
calcio-volborthite and vanadiolite are also found. These minerals 
are commonly associated with cerrusite, wulfenite, pyromorphite, 
stolzite and crocoite. 

The writer has compiled a hst of over 400 occurrences of 
vanadium in the four southwestern States. There are 343 in 
Arizona, 28 in New ]\Iexico, 25 in California and 19 in Nevada. 
All but 8 are occurrences of lead vanadate and similar minerals. 
Of the 64 deposits that show commercial possibilities, 43 occur 
in shattered zones at or near the contact of limestone and either 
rhyolite, basalt, diorite or diabase. One of the largest deposits 
consists of lenticular masses up to 40 ft. wide, 5 ft. thick and 100 
feet long (12.2 x 1.5 x 30.4 m.). The strike of these ore lenses 
is almost at right angles to that of intruding dikes of diabase and 
basalt. 

In all the lead vanadate deposits, the minerals are limited to the 
secondary zone only, and as a rule these secondary zones are 
rather shallow. Only twelve of the deposits extend beyond a 
depth of 250 ft. {76 m.). In all cases no vanadium is found 
below water level. In the old Exchequer mine water was not 
encountered till a depth of 900 ft. (274 m.) had been reached, 
and then within 50 ft. (15.2 m.) the cupro-descloizite and vanadi- 
nite that had persisted, in large, well-defined lodes, from the sur- 

' Manuscript received January 27, 1923. 

* Consulting Electro-Metallurgist, Los Angeles, Calif. 

281 



2 82 WII,L BAUGHMAN. 

face, disappeared altogether and were replaced by galena, chal- 
copyrite, sphalerite and pyrites. 

A. Ditte^ attributes the formation of the various vanadates to 
percolating vanadiferous waters acting on other compounds, 
principally those of lead. Arthur L. Flagg and the writer have 
determined that the igneous rocks, associated with the large 
majority of the lead vanadate deposits, contain from 0.04 to 0.11 
per cent of vanadium trioxide and up to five per cent of sodium 
oxide. It is easy to suppose that such rocks could readily become 
a source of sodium vanadate solutions. And as a proof of this 
supposition, great enrichment is generally found at those places 
where such infiltering waters would have met ascending miner- 
alizing solutions or previously formed bodies of cerrusite and 
allied minerals. 

Arthur L. Flagg, in his examination of the U. S. Vanadium 
Company's deposits, found an unknown black mineral, in the 
diabase, that contains a large percentage of vanadium. Work is 
still being done on this mineral to determine its characteristics. 
At present it appears to be ilmenite with part or all of the 
titanium oxide replaced by vanadium trioxide. 

CONCENTRATION OF LEAD VANADATE ORES. 

The concentration of lead vanadate ores is limited to gravity 
methods. Some attempts have been made, on an experimental 
scale, to use oil flotation on sulfadized minerals. Unless heat, 
pressure or a large excess of sodium sulfide is employed one, 
more or all, it is very hard to sulfadize any large amount of the 
lead vanadates. In fact one method of separation of wulfenite 
from vanadinite, both of which have substantially the same spe- 
cific gravity, is to sulfadize and float the lead molybdate and leave 
the lead vanadates in the residue. 

At S. G. Musser's 300 tons per day flotation plant, where wulfe- 
nite was being concentrated, the ratio of molybdenum oxide in 
the heads was three to one. But the ratio in the concentrates 
was twenty-five of molybdenum trioxide to one of vanadium pen- 
toxide. The ore contained some lead tungstate, stolzite, which 
sulfadized readily. The concentrates often contained two per 
cent of tungsten trioxide. 

•Compt. Rend. 138, 1303. 



THE METALLURGY OF LEAD VANADATES. 283 

The lead vanadate minerals are all non-conductors and cannot 
be separated by electrostatic methods. 

The lead vanadate minerals have specific gravities ranging from 
6.0 to 7.0 and the majority of the gangue minerals have specific 
gravities of only half that. It would seem that such ores would 
be amenable to gravity concentration, and several have attempted 
to use wet and dry gravity methods of concentration. Little 
success has been had with these methods, because of the great 
tendency of the lead vanadate to form slimes during the crushing 
and grinding. Often, too, the crystals are so small as to be almost 
microscopic, but even the large specimen crystals will "slime" 
readily. All the lead vanadate minerals are very brittle. 

A common mistake has been to employ ball mills for pulveriz- 
ing of lead vanadate ores. Six different mills using this method 
of pulverizing have proved failures. None has made a recovery 
of more than 50 per cent of the vanadium, when making concen- 
trates containing 6 per cent or over of vanadium pentoxide. Many 
reports, made on some laboratory experiment, have stated differ- 
ently, but none has made good in practice. R. L. Grider, at the 
Vanadium Mines Corporation's* deposits in New Mexico, used 
rolls and with careful classification was able to recover 69 per 
cent of the vanadium in a rather low-grade concentrate. The 
Dragon Mining Company was unable to raise the grade of con- 
centrates beyond 4 per cent in vanadium pentoxide, nor to make 
a recovery in excess of 43 per cent from ball feed. Changing to 
rolls raised their extraction to nearly 60 per cent and the grade 
of the concentrates to 5.5 per cent of vanadium oxide. 

The Black Buttes ore contains vanadinite, wulfenite, and cer- 
rusite as valuable minerals, with minor amounts of galena, 
stolzite and crocoite. The gangue is primarily calcite and quartz 
with barytes, fluorspar and iron and manganese minerals. The 
vanadinite crystals are very large, often being 12 mm. (0.5 in.) 
long and 3 mm. (^ in.) in diameter. The writer made tests on 
a one-ton scale with this ore.^ Ball mills, highspeed rolls, and a 
centrifugal impact pulverizer were used for crushing and grind- 
ing. The classified pulp was then fed to an Isbell table, to a Senn 
pan motion concentrator and a Plumb pneumatic jig. The results 
are given in Table I. 

*Min. Sci. Press, 113, 389-391. 



284 



WILL BAUGHMAN. 



The high recoveries made by the centrifugal impact mill are 
due to the fact that it pulverized the ore without the formation of 
a large amount of slimes. This mill works on the principle of the 
Varpart disintegrator and schuledenmuhle, briefly described in 
Richards' Ore Dressing. The mill has no real field for pulverizing, 
except where it is desired to reduce slime losses, as in this case. 
In this field it is supreme. 

Table I. 
Efficiency of Grinding Mills on Vdnadinite Ores. 





Mesh 


Percentage Recovered on 


Mill 


Isbell Table 


Senn Table 


Plumb Jig 


Herman Ball 


40 
40 
30 

40 


41 
40 

62 
83 


45 
47 
68 

89 




HardingeBall 

Rolls H S 


38 
59 


Marks Mill Centrif. 


80 







The Marks mill resembles a centrifugal separator in general 
construction details. In place of a basket a table with thrower 
blades or guides is suspended on the shaft. The table or disc 
revolves at 2,000 r. p. m. The ore is fed to the center and rapidly 
passes to the edge whence it is thrown 7.6 cm. (3 in.), at a speed 
of 4.8 km. (3 mi.) per min., against a heavy, sectional cast iron 
shoe. The impact against this shoe shatters the ore along 
natural cleavage lines and lines of crystallization. The shat- 
tered rock immediately falls to the screening apparatus, the over- 
size being returned for further pulverizing. Primary feed may be 
in 5 cm. (2 in.) cubes. The shoes are kept clean by the blast of 
air caused by the whirling table, and, as the ore is hit but one 
blow before being screened, a close sizing of the product can be 
obtained. 

The disadvantages of the mill are that "rusty" gold is not given 
the scouring or cleaning rub or twist that ball mills or stamps give. 
It is this same rub or twist that produces slimes. The wear on 
the shoes is also rather high. The obvious objection "that it will 
fly to pieces" as yet has had no grounds. Over 40 of these mills 
have been installed and none has had that trouble so far. Sev- 



the; metaIvIvURGy of lead vanadates. 285 

eral have been in steady use for 10 years. A mill costs about 
$2,000, requires only 10 horsepower to run it with its accessory 
feeder, screen and elevator, and is capable of pulverizing 30 tons 
of hard quartz, per day of 24 hours, to 40 mesh. 

One promising field of investigation was not followed out 
according to the writer's wishes ; that is the adjustment of the 
speed of the table so as to shatter the more brittle vanadinite to a 
size permitting its passage through a certain mesh screen that 
would retain the less brittle gangue minerals. The manufacturers 
of the mill have conducted extensive experiments in which they 
separated galena and sphalerite in this manner. They also have 
separated, commercially, strontianite and calcite, recovering over 
90 per cent of the strontium in a product 87 per cent pure. 

PRODUCTION OF VANADIUM FROM THE BLACK BUTTES ORES. 

The metallurgy of the lead vanadate ores of the southwest is 
more of an economic problem than a technical one. There is a 
large amount of low-grade vanadium ore available, most of which 
also carries valuable amounts of gold, silver and base elements. 
In fact, one mine has been shipping vanadium concentrates to the 
smelters for the recovery of gold, silver, copper, and lead, as 
they could find no financially responsible buyer who would pay for 
the vanadium and the precious and base elements as well. 

The Flett-Baughman Company became interested in the Black 
Buttes, and first worked out the concentration problem. These 
concentrates averaged 7.14 per cent vanadium pentoxide, 6.0 per 
cent molybdic oxide, 52.4 per cent metallic lead, 2.2 per cent com- 
bined chromium and tungsten oxides, and $5.00 gold and 42 oz. 
silver per ton. Only small traces of phosphorus and arsenic 
were found. 

In spite of the fact, that at that time, there was considerable 
activity in rare elements, and a great many rare element extraction 
plants were being operated, constructed or projected, the writer 
was uable to find any kind of a reasonable market for the 
concentrates. 

The following described experiments were conducted to ascer- 
tain which was the best and most economical method of extracting 
the various valuable elements from the concentrates. The inves- 
tigation also took into consideration the fact that the ferro- 



286 WILL BAUGHMAN. 

vanadium market is closely controlled through long term contracts, 
by three or four corporations. This rendered it imperative that 
some new product be developed. At first it was planned to 
produce C. P. vanadic oxide, which was quoted at over $10.00 
per lb. in the trade journals. However, the market for this 
product is very limited. The writer's investigations indicate an 
annual consumption of not over 500 lb. 

The writer then started a series of investigations in the pro- 
duction of pure metallic vanadium, although, in view of his 
present knowledge of the rare element business, he can not at 
present see where he expected any large market for the pure 
metal. For additions to steel the standard 30 to 40 per cent 
ferro-vanadium is supreme. Iron has a melting point of 1530° 
C. and vanadium 1720° C. while the alloy (30 to 40 per cent) has 
a melting point of about 1440° C. It will be seen that the addi- 
tion of pure vanadium metal to steel would only raise the melting 
point and offer no compensating advantages. 

The writer is not the only one who has made this mistake. To 
his personal knowledge over twenty companies have been formed 
to produce vanadium oxide on a large scale, all of which expected 
to sell all their product at the quoted prices for the C. P. oxide. 
One corporation spent $700,000 and another $250,000 in the 
same vain attempts. None of these companies planned to use a 
process that would produce an average product better than 85 per 
cent pure, and some even expected to sell the vanadium oxide in 
iron vanadate at the quoted figures. The preparation of 99 per 
cent pure vanadium oxide is not the easy matter that it would 
appear to be ; in fact it is a very difficult chemical operation. 

Hereafter the writer describes the results of his investigations 
in 

1. Chloride volatilization applied to Buttes concentrates. 

2. Baughman process for same ores. 

3. Chloridizing roasting of the U. S. Vanadium Go's ores. 

4. Sodium sulfide leaching of the "Signal" ores. 

5. Production of metallic vanadium. 

CHLORIDE VOLATILIZATION OF THE BLACK BUTTES ORES. 

By using a centrifugal impact pulverizer and gravity concentra- 
tion, the Black Buttes ore yielded a high grade concentra- 



THE METALLURGY OF LEAD VANADATES. 287 

tion, and a high extraction was also made. There was ample 
water not only for mill purposes but also for power, so that the 
logical thing was to concentrate and then determine a suitable 
method of handling the concentrates. 

The Flett-Baughman Co. had been experimenting for some time 
on complex lead-copper-zinc ores, and among other plans had 
done a great deal of work in applying chlorine direct to the ores. 
The idea of chloride volatilization was attractive. Splendid results 
could be easily obtained on a laboratory scale, so that 20-lb. scale 
tests were conducted as described below : 

A rotating silica tube 5 ft. long and 13 in. in diameter (1.5 m. 
X 0.32 m.) and heated by an electrical resistance coil was used. 
The volatilized elements were caught in a stoneware bafifle tower 
15 ft. (4.5 m.) high and 6 in. (15 cm.) in diameter. Tempera- 
tures from 200 to 800° C. were employed. The majority were 
run at 400.° The gases from the tower were dried by passing 
over sulfuric acid and through calcium chloride, and returned 
to the volatilization tube. 

Sodium Chloride. Temperatures of 200 to 600° C. were used. 
Percentages of salt between 20 and 40. Time, up to 24 hours. 
The best extraction was 38.5 per cent of the vanadium volatilized, 
and 36 per cent converted to soluble sodium vanadate. This was 
done at 600° with 25 per cent salt and required 24 hours. 

Magnesium Chloride. Hydrated magnesium chloride is decom- 
posed, by heating, to magnesium oxide and hydrogen chloride, 

MgCl2 + H,0 = MgO + 2HC1 

.Some magnesium oxychloride is also formed, which is in turn 
decomposed by oxygen in the air into magnesium oxide and 
chlorine, 

2MgO -f 2HC1 = MgO . MgCl. + H.,0 
MgO . MgCU -f O = 2MgO + C\, 

Thus a supply of chlorine and hydrogen chloride are generated 
in the tube. 

The best extraction obtained was 43 per cent of the vanadium 
volatilized and 36 per cent of the molybdenum, while 27 per cent 
of the vanadium and 33 per cent of the molybdenum formed 



288 WILI, BAUGHMAN. 

magnesium vanadates and molybdates. These salts are soluble 
in hot water and re-precipitated on cooling; but this gives two 
totally different classes of product to treat further and refine. 

Calcium chloride. Two runs only were made with this reagent. 
Some calcium molybdate and vanadate were formed, and some 
oxychlorides volatilized, but the results were so small that analyses 
to determine percentages recovered were not made. 

In all three of the above series of experiments a gentle stream 
of hot dry air was passed through the tube and absorption tower. 

Ferric Chloride. This is a very expensive reagent to use for 
the purpose of chloride volatilization. Both ferric chloride and 
ferric sulfate with magnesium and calcium chloride to form 
ferric chloride, by interaction, were tried. These are known as 
the Gin methods. Ferric sulfate and calcium or magnesium 
chloride interact thus, to produce calcium sulfate and ferric 
chloride. 

Fe,(SO,)3 + 3CaCL =: 3CaSO, + ZFeCla 

Extractions in excess of 90 per cent of the molybdenum and 
vanadium were obtained. Some magnesium or calcium vanadates 
and molybdates were formed. The high cost of the reagents pre- 
cludes the commercial use of this method at present. Considerable 
lead chloride also volatilized, and by interaction in the tower re- 
produced lead vanadates and molydates. 

Carhon Tetrachloride. One run was made with this reagent. 
An extraction of 98.5 per cent of the vanadium and 98 per cent 
of the molybdenum was obtained. A temperature of 400 to 450" 
C. was employed. Seven hours time was required. The cost of 
this chemical makes the process prohibitive; also a large excess, 
over that theoretically required, must be used. 

Chlorine and Hydrogen Chloride Gases. Chlorine alone does 
not give a good extraction. It is necessary partially to reduce the 
ore, preferably by reducing gases, before applying the chlorine. 
Hydrogen chloride alone gives a splendid extraction of the molyb- 
denum, but does not give as satisfactory results for vanadium. 
The method used was as follows : 

The concentrates were first heated for 2 hr. at 400° C. in an 
atmosphere of natural gas. Equal portions of chlorine and hydro- 



THE METALLURGY Of LEAD VANADATES. 289 

gen chloride gas were then passed through the tube for 4 hr. 
longer. The reactions are rather complex but may be expressed 
as: 

•s^VgOs + C^'H^ = -rV^O^ + pCO + qCO^ + rH^O 
V^O, + 3CI2 = 2VOCI3 + O2 

V2O5 4- 6HC1 = 2VOCI3 + 3H2O 
M0O3 + 2HC1 = M0O2CI2 + H^O 

WO3 + 2HC1 = WO2CI2 + H2O 

CrOa + 2HC1 = CrO^Cl^ + H,0 

The last four are reversible and on catching the volatilized ele- 
ments in water in the absorption tower, they are re-converted into 
their respective oxides and the acid is regenerated. Considerable 
heat is evolved at the same time. 

Some of the molybdenum and tungsten oxides were reduced 
during the preliminary reduction. These reduced oxides interact 
with chlorine as follows : 

M0O2 + CI. = M0O2CI2 
WO2 + CI2 = WO2CI2 

The large amount of regenerated acid causes the re-solution of a 
large portion of the precipitated oxides, and in addition to this 
some very complex rare element compounds are formed, which 
give all kinds of trouble in later refining steps. The most serious 
objection was the large amount of gas required to conduct the 
operation. Most of the silver was also volatilized and formed 
silver vanadates that made its recovery more expensive. Lead 
chloride volatilized also, although most of the lead was reduced 
in the first step to metal and remained in the residue as fine 
pellets. 

From an economic standpoint these experiments were failures. 
Technically a large percentage of the rare elements were recov- 
ered. The best run was at 400° C. ; time 2 hr. ; reduction, 4 hr. 
chloridizing volatilization ; vanadium recovered 96.5 per cent ; 
molybdenum recovered 98 per cent. 

BAUGHMAN's process for the TREATMENT OF LEAD VANADATES. 

After the failure of the chloride volatilization experiments, the 
Flett-Baughman Co. initiated some new experiments on the Black 



290 WILIv BAUGHMAN. 

Buttes ore. The method selected was first to smelt the con- 
centrates, producing a vanadiferous slag and a lead bullion 
containing the gold and silver. This step was analogous to the 
first steps of Gin's process and to Grider's process. 

The concentrates were smelted in an electric furnace of a tilting 
type. It was constructed along the lines of the Girod tilting 
resistance furnace described in Bulletin 77 of the Bureau of Mines 
page 109. In addition to the resistance heating, provision was 
also made for using it as an arc furnace by placing three 5 in. 
(12.7 cm.) graphite electrode stubs, well rammed with magnesite 
and tar in the bottom, and suspending a 3 in. (7.6 cm.) graphite 
electrode, through a hole in the cover, from the ceiling, by 
wires, attached to the electrode holder. The electrode was raised 
and lowered by passing these wires through pulleys to a hand 
operated winch and drum. The furnace also had a tap hole at the 
bottom, the use of which will be seen later. The melting chamber 
was 15 in. (39 cm.) in diameter by 22 in. (54 cm.) high. 
Alternating current was used to heat the resistors, and direct cur- 
rent from a motor generator set with two generators of 40 to 60 
volts each and capable of being connected in either series or 
parallel supplied the arc current. The generators were each 
capable of supplying a current of 900 amp. The furnace, how- 
ever, drew only 500 amp. except during the starting period. 

The method of operation was to charge 150 lb. (68 kg.) of 
concentrates, 15 lb. (6.8 kg.) of pulverized coke and 30 lb. 
(13.6 kg.) of soda ash, thoroughly mixed, into the furnace and 
melt the same by the resistance heaters. Two-thirds of the above 
charge was put in the furnace at the start, and the balance as soon 
as the first portion was melted. 

At the end of 1.5 hr. the lead was tapped from the bottom 
notch, and as soon as this was completed a pipe was inserted in 
the notch and quickly luted with fire clay. A blast of air at 20 lb. 
(9.1 kg.) pressure supplied by a large Crowell blower was then 
forced through the slag. The slag changes from green to blue 
in color, when cooled for tests, by plunging slag rod in water. 
The furnace was then tilted and the molten slag poured into hot 
water to granulate it and render it more soluble. Up to this 
point the process is substantially the same as those of Gin and 
Herrenschmidt. 



THD METALLURGY OF h^AD VANADATES. 29 1 

The solution in which the slag was poured was filtered off and 
the residue mixed with one fourth its weight of caustic soda. This 
mass was then roasted at a low temperature, about 300° to 400° 
C, for 2 hr. It was then digested 2 hr. with the original solution 
from which it was first filtered. The solution was filtered again 
and the residue, which contained less than 3 per cent of its 
original vanadium content, was discarded. To assist in the forma- 
tion of the metavanadate of soda, peroxide of hydrogen was 
added at first, later the same results were obtained by using 
ozone. This ozone was made from oxygen, from the electrolytic 
cells used in a later step in this process, passed through an 
ozonater. 

A calculated amount of sodium sulfide was also added to the 
solution while the roasted slag was being digested. This is to 
sulfadize, thus rendering it insoluble, any zinc or lead that might 
have remained in the slag. Sodium aluminate, also in calculated 
amounts, was used to precipitate the phosphorus. The digester 
was made of half inch sheet steel ; it was mechanically agitated 
and steam heated. 

Fractional Crystallization. 

After the solutions were filtered from the residue, they con- 
tained sodium chloride, vanadate, sulfate, carbonate, molybdate, 
tungstate, chromate, hydroxide and aluminate. This solution 
was then evaporated in a triple effect evaporator to 22° Be., 
and the sodium sulfate, aluminate and chloride allowed to crystal- 
lize out and be removed. The next fraction was removed at 26° 
Be. and contains most of the vanadium as the various sodium 
vanadates. However, this fraction is not pure, as it contains 
some molybdenum and chromium as complex molybdo-chromo- 
sodium vanadates. The third crystallization is at 30° Be. and it 
contains some sodium vanadate with sodium carbonate. These 
salts, after calcining, are used for the original flux in smelting the 
ore. Thus no vanadium is lost in the cycle of the process. The 
last fraction is obtained at 33° Be. It yields the sodium molyb- 
dates, chromates and tungstates with some vanadium as complex 
salts. The second and last fractions are mixed together and used 
in the next step. 

Since these experiments, the writer has developed a system 



292 



WILL BAUGHMAN. 



Flow Sheet. 
Baughman Process for Treating Complex Lead-Rare 



Concentrates 



Element Ores. 



Coke 

\ 



i ^ 



Soda Ash 



Air. 



Caustic Soda 



Sodium Aluminate 
Sodium Sulfide 



r 



No. 1 
No. 2 
No. 3 
No. 4 



OZONATER 
I 

Oxygen 1 



ELECTRIC FURNACE 

t ^ >Pb, Au, Ag Bullion 

— >■ Slag Treatment 

\ 

>► STIR TANK 

FILTE R > \ 

I 1 

> MIXER 

\ I 

MUFFLE FURNACE 
\ -> DIGESTOR <— 

_J_ I X 

^ T-TT 'TTJTD —^ ^ F, residual Pb and Zn 

i^lLiliR -T^ -^ Tailings, Cu, etc. 

t 
EVAPORATOR 

\ 

CRYSTALLIZING VATS 

Soda nitrate, Sodium chloride and sulfate 
/"^—Sodium vanadates 

I- 



J 



Sodium carbonate-^MUFFLE FURNACE- 
Sodium tungstates, molybdates, chromates 



DISSOLVER< 

-ELECTROLYSIS CELLS 



^ 



Hydrogen i I 

Water^-DECOMPOSITION VAT 

V } \ 



Na OH Solu. 



I 



MERCURY PUMP-' 



I 



SUPER CENTRIFUGE 

I 

FILTER 

PUMP — > 

^ CONDENSING 
( CHAMBERS 
Molvbdic Oxide 



^ 



VOLATILIZATION TUBE- 
— >'First Step 

'' > Second Step Vanadium Trioxide 

Residue: Metallic Tungsten, Chromium and Titanium oxides and metal 



THE METALLURGY OF LEAD VANADATES. 293 

of fractional crystallization for such complex mixtures, that yields 
each salt separately and in pure condition. He has also found 
the method of preventing the formation of the complex molyb- 
denum-chromium-vanadium compounds with sodium. This 
system is rather complicated and is too lengthy to describe here. 

Electrolysis of Sodium Salts. 

The mixed vanadates, chromates, molybdates and tungstates 
of sodium were then dissolved to a 20° Be. solution. This was 
done in a small tank with a mechanical stirrer. From there the 
solution went to the electrolysis cells, which were similar to the 
mercury cathode Solvay cells for producing chlorine and caustic 
soda. The salts are decomposed, the sodium entering the cathode 
and the rare element oxides remaining in a semi-colloidal form 
in the electrolyte. 

The sodium amalgam was kept in constant circulation between 
the electrolysis cells and outside decomposition vessels by a mer- 
cury pump. The amalgam was decomposed by the action of water 
in this outside vessel, to mercury and caustic soda; considerable 
hydrogen was also evolved. 

The reactions in the electrolytic cell might be expressed ; 

2NaV03 + electricity = 2Na (in Hg.) -f V^O, + O 

and the decomposition of the amalgam as: 

NayHg^ + sU.O = xUg + yNaOH -j- sU. 

The regenerated caustic soda was used again in the previous 
steps of the process. 

The electrolyte was also kept in constant circulation. It was 
passed through a Sharpies centrifuge and then filtered. This 
eliminated serious trouble that had been encountered previously, 
due to the semi-colloidal condition of the suspended oxides of the 
rare elements. The filtrate is used to dissolve fresh amounts of 
the crystallized salts from the previous step of fractional crystal- 
lization. 

A current of 8 volts was used. The cells required 1,800 amp. 
Seven were connected in series. The anodes were of platinum 
gauze, but fused iron oxide would have been as satisfactory. 



294 WILL BAUGHMAN. 

Arrangements were made for collecting the hydrogen and oxygen 
evolved, for use in refining the oxides. 

The electrolysis of sodium vanadate solutions in diaphragm 
cells has been proposed by W. F. Bleecker^ and investigated by 
S. Fischer.® The w^riter used a mercury cathode cell, because the 
oxides produced in diaphragm cells always contained impurities 
from the disintegration of the diaphragms. 

Separation of the Oxides. 

The filtered oxides were washed and dried and then treated 
by one of the two following methods : 

Electrolytic Method. The mixed oxides were dissolved in a 
stoneware agitator, by dilute hydrochloric and sulfuric acids. 
This solution, as near neutral as possible, was again electrolyzed 
in a mercury cathode cell. The tungsten, molybdenum and 
chromium passed into the amalgam, the vanadium again separated 
as the oxide, considerable chlorine was given oflf and both phos- 
phorus and arsenic, which had been added for purpose of testing, 
were completely volatilized. Some vanadium remained in solu- 
tion. The mercury was pumped through a chamois skin amalgam 
filter instead of into the outside decomposition vessel. Excess 
mercury was strained and pressed out of the amalgam, which 
was then retorted. The mixed chromium, molybdenum and 
tungsten metals remaining in the retort were then ignited to the 
oxide, (they were highly pyrophoric) and the molybdenum oxide 
removed from the chromium and tungsten, which was discarded, 
by volatilization. This is identical with the first step of the other 
method of separation of the rare element oxides and will be 
described later. 

Volatilisation Method. The volatilization tube previously 
described was used. The separation was conducted in two steps. 
In the first the molybdenum trioxide was volatilized in a current 
of oxygen. The oxygen was a by-product of the electrolysis of the 
rare element sodium compounds. The molybdenum trioxide 
was completely volatilized in 6 hr. at a temperature of 800" C. 
Increasing the temperature beyond this point favored the forma- 

»Met. and Chem. Eng. 9, 503 (1911). 

« Trans. Am. Electrochem. Soc. 30, 175 (1916). 



THE METALLURGY OE LEAD VANADATES. 295 

tion of molybdo-vanadates, and at 850° only 85 per cent of the 
molybdenum trioxide was volatilized. 

In the second step, hydrogen from the decomposition cell of 
the electrolysis cells was passed over the mixed oxides of vana- 
dium, tungsten and chromium. At the same time the temperature 
was raised to 1400° C. The hydrogen gas was preheated as was 
the oxygen gas used in the previous step. In this step the 
tungsten and chromium were reduced, the former to metal and 
the latter to sub-oxide and metal. Titanium was also reduced 
to the lower oxide. The vanadium pentoxide was reduced to the 
trioxide and then became volatile. At the end of 18 hr. it was 
completely volatilized. The tungsten-chromium residue was dis- 
carded. 

Removal of Phosphorus and Arsenic. 

The Black Buttes ore contained no trace of arsenic and very 
little phosphorus. A large majority of the lead vanadates con- 
tain these impurities. From acid solutions arsenic may be com- 
pletely removed by passing over copper, copper arsenide being 
formed. Where the solution is further treated by passing over 
iron, to reduce the vanadium so as to make precipitation easier, 
the copper dissolved by the excess acid will be re-precipitated. 
From acid solutions, preferably hydrochloric, the phosphorus can 
be completely removed by precipitation as zirconium phosphate. 
This precipitation can be obtained from quite strong acid solutions. 
Zirconium hydrate (crude) prepared from zirkite is dissolved in 
hydrochloric acid and used as a precipitant. 

From alkaline solutions sodium aluminate, made by dissolving 
aluminum shot in concentrated caustic soda solution, secures a 
complete precipitation of the phosphorus and also a little of the 
arsenic. 

From neutral solutions, strontium nitrate, made by dissolving 
the mineral strontianite in commercial nitric acid, will precipitate 
all the phosphorus and arsenic, together with most of the tungsten 
and molybdenum present, but it precipitates very little vanadium. 

The electrolysis of any acid solution containing chlorides 
secures the complete volatilization of the arsenic and most of the 
phosphorus. 



296 WILL BAUGHMAN. 

CHLORIDIZING ROASTING AND LEACHING OF LEAD VANADATE ORES. 

At several of the vanadium deposits, of the southwestern part 
of United States, there are valuable amounts of gold and silver 
in the ores, that are not recovered by concentration, and not infre- 
quently there is so much barytes present that it is impossible to 
obtain a high grade concentrate. Where such conditions exist 
and there is a large amount of low grade ore available, chloridiz- 
ing roasting and leaching is an ideal treatment method. 

These experiments were first tried on the Buttes ore, but 
abandoned when suitable concentration methods were found. Later 
the process was the subject of an extensive investigation by the 
U. S. Vanadium Development Company, under the direction of 
the writer. Later the Consolidated Vanadium Company built 
a 25 ton per day plant to use the same method, they being cog- 
nizant of the U. S. Vanadium Co's experiments. 

Chloridizing roasting and leaching has been in successful use 
in an ever expanding plant at Park City, Utah, at a cost of about 
$3.00 per ton. The ore treated there contains 6 to 14 oz. silver 
per ton, SLOO in gold, a couple of pounds of copper and small 
amounts of lead and zinc. Recoveries as high as 95 per cent 
have been made, 85 to 90 per cent being common practice. This 
process is very simple, is economical on a large scale, and is 
capable of handling very low grade ores.^ Briefly described it 
consists of roasting with admixed fuel in a shaft furnace, and 
leaching with tower acid, precipitating silver and gold on copper, 
copper on iron, and later electrolytically recovering the lead. 

Roasting. 

A mixture of 6 to 9 per cent salt, 1 to 3 per cent coal dust, 1 to 
2 per cent manganese dioxide, and 2 to 8 per cent pyrites is thor- 
oughly mixed, moistened with tower acid till the mixture will 
retain the imprint of the fingers when tightly pressed. This mois- 
ture varies from 5 to 10 per cent according to the fineness of the 
ore. 

A deep bed of coals is started in the bottom of the shaft roaster 
and the roast mix charged to a foot of depth. As soon as the 
roast shows through 3 ft. (0.9 m.) more of charge is added, and at 

' The method is fully described in Trans. Am. Inst. Min. and Met. Engr., 49, 
183-197, and has also been the subject of several articles in various mining journals. 



THE METALLURGY OF LEAD VANADATES. 297 

the next appearance of the roast 4 ft. ( 1.2 m.) more, which is about 
the maximum depth to which the blower can supply air. The 
bottom of the shaft is all a grate, with a wind box underneath. 
Air is supplied at about 1 lb. (0.45 kg.) pressure. 

Temperature is controlled by rate of blast. It is better to roast 
too slowly than too fast. Temperature range may be between 
600 and 800° C. For the U. S. Vanadium ores 650 to 750° C. 
was found best. Too high a temperature causes clinkers and 
melts the salt, forming a thin glaze on the ore particles. However, 
caked masses are a sign of good roasting. Slimes and fines cake, 
not clinker, readily at the proper temperatures, and form an easily 
leached product. 

Were a dry charge used, a great deal of the valuable elements 
would be volatilized, but the moisture is concentrated about a foot 
ahead of the roasting zone and thus entraps any volatilized ele- 
ments, so that the only volatilization occurs at the end of the roast 
when the temperature is lowest. Even then the volatilized ele- 
ments are caught in the absorption tower, where the barren mill 
brine is returned in order to catch the acids of the roasting fumes. 

The reactions during roasting are very complex. In general 
the following may be said to occur : 

Chlorine is produced by interaction of salt and sulfur trioxide, 
obtained from the pyrite, at elevated temperatures, 

2NaCl -f 2S0, = Na^SO, + SO^ + CU 

Chlorine is also obtained from salt, silica and oxygen, 

2NaCl + SiO^ + O = Na^SiOs -f Cl^ 

This nascent chlorine acts strongly on metals and sulfides 
present, and to a lesser degree on oxides, 

Au + 3Cl = AUCI3 
Cu,S + 4C1 -f 30 = 2CuCl + SO3 

Some metallic chlorides are formed direct, 

2NaCl -f PbSO, = PbCL -{- Na,SO^ 

Sulfur dioxide may be converted in part to trioxide by catalysis 
by silica or peroxidized by iron oxide, 

20 



298 WILL BAUGHMAN. 

2SO, + 30 + SiO^ = 2SO3 + O2 + SiO^ + 22,600 cals. 
SOo + 3Fe203 = SO3 + 2Fe304 

After reduction of the vanadium from the penta to tetra state 
it is readily attacked by the chlorine (in the roaster) to form 
the volatile oxychlorides thus, 

V2O5 + C = V2O4 + CO 

V2O4 4- CI, = 2VO2CI 

V2O, + 3CI2 = 2VOCI3 + O2 

These are decomposed by the w^ater in the absorption tower, 
and redissolved by the excess acid, 

2VO2CI + H2O = V2O5 + 2HC1 
2VOCI3 + 3H2O = V,0, + 6HC1 

In the tower chlorine and sulfur dioxide form sulfuric and 
hydrochloric acids, 

C\, + SO2 + 2H2O = H2SO, + 2HC1 

Steam and silica interacting v^^ith salt form hydrochloric acid 
in the roaster, 

2NaCl + SiO, + H2O = Na^SiOa + 2HC1 

Sulfur trioxide, steam, and salt also form hydrochloric acid in 
the roaster, 

2NaCl + SO3 + H2O = Na^SO, + 2HC1 

In turn the sulfuric acid in the brine acts upon the salt, so that 
the free acid is hydrochloric, 

H2SO, + 2NaCl = Na^SO, + 2HC1 

While unable to prove it in every way the writer has strong 
evidence that salt and vanadium pentoxide form sodium vanadate, 

2NaCl + V2O5 + O = 2NaV03 + Cl^ 
6NaCl + V.O^ 4- 30 r= 2Na3VO, + 3CI2 

Roasting in reverberatories or mechanical furnaces does not 
give the results that the Holt shaft roaster does. The slower 
heating and the much longer cooling is the reason for this. At 



the; me;tai,l,urgy of lead vanadati;s. 299 

Park City, Theodore P. Holt used ore through 0.25 in. (0.64 cm.) 
mesh, but the writer has determined that the ore should be crushed 
to 0.0625 in. (1.6 mm.) mesh at least when treating vanadium 
ores. 

The addition of manganese is the result of the writer's investiga- 
tions. In his work on complex lead-zinc-copper sulfide ores he 
found that he could convert over 90 per cent of these metals to 
sulfates during the roast by adding manganese dioxide in the 
form of pyrolusite to the charge. These complex ores were after- 
wards leached with dilute sulfuric acid to remove the copper, 
which was precipitated as cuprous chloride, and the zinc which 
was precipitated, after purification of the solution, by electrolysis. 
The lead, gold and silver were dissolved by a strong brine. The 
precious metals were precipitated on copper and the lead by elec- 
trolysis, at the same time regenerating the chlorine in the brine, 
by which the gold was attacked and made soluble. The difficult 
step of this process lay in the roasting so as to form a maximum 
amount of sulfate, without forming insoluble ferrites or excessive 
oxide. The accidental addition of manganese dioxide gave such 
wonderful results that the writer tried it in chloridizing roasting 
also. For vanadium ores it acts as an oxidizer, and assists in 
releasing a large amount of acid. Many large and small experi- 
ments have proved its value. 

Lixiviaiion and Precipitation. 

For the U. S. Vanadium Go's ores a pulp ratio of one to five 
was found best. A strong acid brine with a gravity of 20 to 
24° Be was used. The temperature was to be maintained at 60° 
C. by the use of steam. The brine was applied in counter current 
to the ore. 

The greenish yellow solution was returned to the tower and 
leaching vats till it was a strong green in color and contained 
10 g./L. of vanadium or over. The acid solution was then partly 
neutralized and passed over copper rififles to precipitate the gold 
and silver. This step also removes the arsenic as arsenide of 
copper. 

The solution Avas next passed over scrap iron and the copper 
precipitated. At the same time the nascent hydrogen from the 
action of the excess acid on the iron, and in fact the iron itself. 



300 WILL BAUGHMAN. 

reduced the vanadium from the penta to tetra state and the 
molybdenum to the molybdous state. The solution became a dark 
blue. 

The next step was the electrolytic recovery of the lead, as 
sponge lead, at the same time the vanadium was further reduced 
to the tri-valent state. Insoluble anodes were used for the sponge 
lead electrolysis at first. 

Flow Sheet. 
Chloridizing Plant for U. S. Vanadium Development Co. 

STORAGE BINS 
Ore Salt Pyrites Pyrolusite Coal Dust 

I \ \ \ \ 



r 



MIXER i y 

I /-TOWERS-EXHAUST FAN 

i t 

HOLT SHAFT ROASTER 

i r- 

LEACH SYSTEM ^Tailings 

Tronaormagnesite [^^^eUTRALIZING TANK Phosphorus 
Zirconium Chloride ] ■ 

Scrap copper ^-COPPER RlFFLES->Gold, Silver Arsenic 

Scrap iron ^IRON RIFFLES ^Copper 

ELECTROLYSIS CELLS >^ 



ANODE COMPARTMENT Iron vanadate and molybdate 

(to refinery) 
CATHODE COMPARTMENT Sponge lead 

A mixture of vanadium and molybdenum oxides together with 
manganese, iron, lime and other elements as hydroxides and 
carbonates was obtained by using crude trona as a precipitating 
agent. The writer found later that calcined magnesite was 
cheaper, gave a higher grade precipitate, and that the precipitate 
was easier to filter than that from the soda precipitation. 

Later on soluble iron anodes were used, in order to lower the 



THE METALLURGY OF LEAD VANADATES. 30I 

power requirements for the precipitation of the lead. We were 
surprised to find that the vanadium and molydenum were com- 
pletely precipitated as iron vanadates and molybdates by purely 
anodic processes. Xo extra power was required, although a dia- 
phragm to prevent the mixing of the anode products and the 
sponge lead was necessary. 

The mixed vanadates and molybdates are of a much higher 
grade than any obtained by chemical precipitation. They are also 
very granular and easily filtered and washed. 

A certain amount of the brine should be rvm to waste on each 
cycle to prevent the fouling of solution by sulfates. The wash 
water and the salt added with each roast will in general keep the 
brine up to standard. 

The disadvantages of the process are that it can not be applied 
to ores containing any large amount of calcium or magnesium, 
and that for its economic operation plants should have a capacity 
of at least 50 tons per day. 

The Consolidated Vanadium Co. built a 25-ton plant using this 
process, as worked out by the writer, which was closed for 
internal and legal reasons shortly after its initial operation. The 
best run they made gave an extraction of 76 per cent of the 
vanadium in an ore cotaining only 0.16 per cent vanadium pen- 
toxide. The gold and silver recoveries approximated those of 
Holt at Park City. 

The phosphorus in the ore was eliminated at the time of neu- 
tralizing the leach solution. This was done by adding a solu- 
tion of zirconium chloride, which was prepared by dissolving 
crude zirconium hydroxide in hydrochloric acid. The zirconium 
hydroxide may be prepared in any manner from zirkite. The 
phosphorus is precipitated completely, even from highly acid solu- 
tions, as zirconium phosphate. 

Chloridizing roasting has been used successfully for many years 
in Colorado for the treatment of roscoelite. 

The precipitation of iron vanadate and molybdate by anodic 
reaction is analogous to the old Luckow paint processes for pre- 
paring lead carbonate and chromate. Warren F. Bleecker has 
patented^ certain phases of the precipitation of vanadium by this 
method. 

«U. S. Patent 1,105,469. 



302 WILL BAUGHMAX. 

The Consolidated Vanadium Co. also developed a soluble anode, 
which consisted of a wooden basket in which machine shop turn- 
ings worth only $6.00 per ton were used. The plates used before 
had cost $50.00 per ton. 

The U. S. Vanadium Co's ores contained an average of $2.00 in 
gold and 4 oz. silver per ton, 0.57 per cent vanadium oxide and 
0.52 per cent molybdic oxide. They have a tremendous amount of 
this grade of ore. It also contains small amounts of copper, lead, 
arsenic and phosphorus. 

The tests for adaptability of these ores to chloridizing roast- 
ing and leaching were concluded on 200-pound scale experiments. 
Extractions ranging from 72 per cent to 76 per cent of the rare 
elements, and 90 to 95 per cent of the precious metals, were 
readily obtained. 

Sodium Sulfide Leaching. 

The vanadium minerals of the "Signal" ores are primarily 
cuprodescloizite and vanadinite, with minor amounts of vanadio- 
lite and volborthite. The gangue is principally calcite with fair 
amounts of barytes and quartz. A typical analysis is : Gold 
$19.00, silver 6 oz. per ton ; copper 2.5 per cent ; lead 3.5 per cent ; 
vanadium pentoxide 2.25 per cent; lime 25 per cent; barytes 18 
percent ; P, As, Ti, ]\lo, W, none. 

The large amount of lime prevents the use of chloridizing 
roasting. Concentration is seriously interfered with on account 
of the bar}'tes present ; also the gold and silver are not amenable 
to concentration. Certain economic factors had to be considered 
in designing a process for these ores. The plant had to be simple 
in construction and operation. The first cost was to be kept as 
low as possible. It was also desired that the vanadium be recov- 
ered as a readily marketed compound, so that the expense of a 
refinery and ferro-alloy plant could be dispensed with. 

Alan Kissock" has successfully employed sodium sulfide for 
the extraction of molydenum from wulfenite. S. G. Musser also 
built a plant using this process. Kissock used counter current 
decantation for treating the ore. Musser used theoretical propor- 
tions and applied heat and pressure. The reaction is substantially, 

PbMoO, + Na,S = PbS -f Na,MoO, 

»U. S. Patent 1,403.035. 



THE METALLURGY OE LEAD VANADATES. 303 

Both of them pecipitated the molydenum by calcium chloride. 
This was a by-product of S. G. Musser's plant for treating 
residual brines from the extraction of salt from sea water. 

Na^MoO, + CaCl^ = CaMoO, + 2NaCl 

Alan Kissock^° has patented the process of using calcium 
molybdate so produced as a direct addition to steel, the carbon in 
the bath reducing the oxide, which readily alloys with the metal. 
Parenthetically, it may be remarked here that calcium vanadate 
can not be employed in a similar manner. Both Mr. Kissock and 
his assistants and the writer have repeatedly tried to achieve this 
end, but have failed in all cases. The writer has used scheelite 
concentrates (CaWO^) in a like manner for adding tungsten to 
steel. 

Warren F. Bleecker and W. L. Morrison" have described 
experiments in which they added calcium vanadate, with suitable 
reducing agents as aluminum or silicon, direct to the bath. They 
obtained splendid results. 

Because of the great ease with which molybdenum could be 
extracted from wulfenite by sodium sulfide, the writer initiated 
experiments to ascertain whether or not the "Signal" ores could 
be treated in a similar manner. 

Laboratory tests soon showed that simple counter current lixi- 
viation was not sufficient. Heat, pressure and agitation all increase 
the efficiency. For some ores it is necessary to add sodium poly- 
sulfide, in order to take care of the cerrusite and similar minerals 
that also consume sulfur by becoming sulfadized. Other ores 
particularly those containing vanadiolite and calcium vanadates 
require the addition of caustic soda. The sulfadizing and forma- 
tion of sodium vanadate reactions are very complex, but for sim- 
plicity's sake may be expressed thus: 

rzn 

- Pt 

cuprodescloizite ' Cl 

3Pb3(VO,), . PbCla -f 10Na,S = lOPbS -f 6Na3VO, + 2NaCl 

vanadinite 

The use of sodium sulfide as a solvent for vanadium formed 
part of a patented treatment method of G. Fester.^^ Its similar 

>«U. S. Patent 1.385,072. 

"Met. and Chfem. Eng. 13, 492-494 (1915). 

"German Patent 294,932 (1917). 



(Cu . Pb . Zn), V,0, -f 2 Na.S = 2 ] pbj S -f Na,V/J, 



304 WILI. BAUGHMAN. 

use has been recently patented in the United States by one of 
S. G. IMusser's former laboratory assistants. 

After the usual laboratory and small scale experiments, the 
writer specified the following procedure, which was carried out in 
a 25^-ton per day scale at S. G. Zinsser's plant. The ore was 
pulverized to 0.025 in. (0.63 mm.) mesh in a ball mill. It was 
then charged into a rotating drum made of 0.5 in. (12.7 mm.) 
boiler plate, which was 8 ft. (2.4 m.) long, and 3.5 ft. (1.1 m.) 
in diameter. It had a tight fitting manhole cover and hollow 
axles, so that steam could be supplied for heating and pressure. 
Several blades on the inside of the drum aided agitation as the 
drum was revolved. Three solutions were successively employed, 
the one containing the least sodium sulfide first and the strongest 
sodium sulfide liquor last. 

The second solution became the first solution for the next lot of 
ore to be treated, and the third solution the second. A new third 
or strong sodium sulfide solution was prepared, by dissolving com- 
mercial sodium sulfide in water to saturation at average tempera- 
ture, and then diluting with an equal amount of water. The ore 
was digested for 4 hours, 0.5 ton to the lot. A temperature of 
90° C. and a pressure of 120 lb. was maintained. At the end of 
this period the ore was discharged and filtered. The residue can 
be easily treated by oil flotation for the recovery of both the 
precious and base metals. Experiments in this case were made 
with a K & K laboratory flotation machine. 

The filtered solution was then evaporated in a single effect 
evaporator to 20° Be. and sent to the crystallizing tanks, where 
the sodium sulfate and chloride were crystallized out. It was 
then evaporated to 26° Be. and crystallized, yielding a mixture 
of sodium ortho, pyro, and meta vanadates. 

For a plant situated on the desert, where the vanadium deposits 
are, the best evaporator would be spray ponds. These evaporators 
consist of parallel pipes, with many small perforations on the top 
side, which are suspended about 10 ft. (3m.) above a shallow 
pond. The hot dry desert wind blowing through the spray causes 
a very rapid evaporation. A centrifugal pump keeps the solution 
in circulation. A 3 in. (7.6 cm.) centrifugal pump will supply an 
evaporator capable of evaporating 20,000 lb. (9,071 kg.) of water 
per day of average desert weather. The writer has used such 



THE METALLURGY OF LEAD VANADATES. 305 

evaporators successfully in evaporating borax, potash, trona, 
potash alum and nitrate liquors at desert deposits. 

The residual liquor from the sodium vanadate crystallization 
contains some sodium vanadate, sulfide, sulfite and hypo sulfite. 
It is returned to the leach system with the new or strong sodium 
sulfide liquor. 

The mixed sodium vanadates are a commercial product. They 
can also be converted into the oxide by treating with either 
sulfuric or nitric acids, baking to dryness, and then washing or 
rather leaching and filtering to remove the soluble sodium nitrate 
or sulfate, and recovering the insoluble vanadic oxide. This 
process has splendid possibilities in its limited field. The cost 
of plant and of operation are both low. This method can not be 
used if the ore contains phosphorus, molybdenum, tungsten or 
other impurity forming soluble compounds with the sodium sul- 
fide. These impurities would render the product worthless. 

The writer has developed a method of using such mixed sodium 
vanadates with some iron oxide and metal and aluminum for 
production of ferro vanadium by the metallo-thermic method or 
with silicon in the electric furnace. This method will be described 
at some future date. 

Metallic Vanadium. 
The writer has developed a method of making pure metals 
from difficultly reduced oxides. He has prepared vanadium 
which was over 99 per cent pure by this method, and has 
also produced very pure lithium, tantalum, titanium, thorium and 
cerium by the same method. The writer had hoped to be able to 
describe this method in this paper but business reasons have pre- 
vented, and he can only hope to make it the subject of some 
future paper. In the development of a process for making metal- 
lic vanadium the writer duplicated the work of previous investi- 
gators, and devised a method of reduction with lithium metal. 
His experiments along these lines are described hereafter. 

Sefsfrom's Method. Sefstrom, the discoverer of vanadium, 
found that on dissolving iron containing vanadium with dilute 
hydrochloric acid, that the vanadium remained in the residue with 
the graphite and other insoluble matter. Ferrovanadium may 
be dissolved in dilute hydrochloric acid, while passing a stream of 
21 



306 WILL BAUGHMAN. 

carbon dioxide, and about one half of the vanadium content of 
the ferro-alloy will be recovered as vanadium metal. The 
vanadium carbide and graphite present in the ferro is also insolu- 
ble, and will be an impurity in the vanadium residue. Working 
with ferro prepared from pure materials in magnesite crucibles 
by the alumino-thermic method, and dissolving the alloy with 
C. P. acid, the writer was able to prepare vanadium metal over 
90 per cent pure. This method has been used for some time in 
Germany, to prepare the vanadium metal sold to experimenters 
and colleges. It is in the form of fine glistening scales, much 
resembling graphite in appearance. It can be fused in vacuo only, 
and even then contains a large percentage of vanadium monoxide. 
It oxidizes readily in the atmosphere. 

Roscoe's Method. This method is fully described in Roscoe and 
Schorlemmer's Treatise on Chemistry pp. 279 to 282. The writer 
attempted to duplicate this method on a 1 lb. (0.45 kg.) scale. 
He used a rotating silica tube 4 in. (10 cm.) in diameter and 
3 ft. (90 cm.) long, which was heated electrically by a resistance 
coil. The hydrogen train and other accessories were the same 
as specified by Roscoe only of suitable size. At the end of 6 days 
less than half the chloride had been reduced to metal, but on sub- 
stituting a smaller tube and using a silica boat containing one 
gram, nearly 90 per cent of the chloride was reduced to metal in 
48 hr. The preparation of the chloride is a very difficult matter 
in itself, and as this method offered no commercial possibilities, 
no further experiments were conducted. 

Prandtl and Bleyer's Methods. They describe a method^^ of 
preparing metallic vanadium up to 94 per cent pure. They used 
a can 10 in. (25 cm.) high and 5 in. (12 cm.) in diameter. In the 
bottom of this they tamped a layer of fluorspar 1.5 in. (4 cm.) 
thick. They then placed a glass tube 10 in. (25 cm.) long and 
2 in. (5 cm.) in diameter in the center and tamped fluorspar 
around this tube. The next step was to tamp a mixture of 
calcium, aluminum and vanadium oxide inside the tube and with- 
draw the tube by twisting and turning. The mixture was then 
ignited by a "thermit cherry." 

No data were given as to the size of the particles of aluminum 
and calcium nor the proportions of reducing agent and vanadium 

"Z. anorg. Chem. 64, 217-224. 



THE METALLURGY OF LEAD VANADATES. 307 

oxide, save that there are to be 69 parts of calcium for 31 
parts of aluminum. It is assumed that they planned on the fol- 
lowing reaction : 

15Ca + lOAl + 6V2O5 = SCa^Al^Os + 12V 

The degree of comminution of the various ingredients in a 
metallo-thermic reaction is of prime importance. Both the tem- 
perature and speed of reduction can be controlled within certain 
limits, solely by regulating the sizes of the different elements 
and compounds used. Dr. Saklatwalla^* has shown that vanadium 
oxide may be reduced to metal in the form of ferro, without the 
excessive formation of carbide or the reduction of silica to siHcon, 
even though carbon and silica be present in large amounts. These 
results were obtained solely by paying attention to size of mate- 
rials. This explains why certain investigators have been unable 
to duplicate the work of others. Different sizes of materials 
were used, hence a different temperature and rate of reduction. 

Prandtl and Bleyer recommend the use of old slag where more 
than 100 g. of vanadium oxide are reduced, to keep down the tem- 
perature ; but the writer obtained better results when no slag was 
used. The writer also used dead burned magnesite, fused in the 
electric furnace and then pulverized, instead of fluorspar in 
several runs. 

The writer used a can 20 in. (51 cm.) high and 12 in. (30 cm.) 
in diameter and rammed the fluorspar around a tube 18 in. (45 
cm.) long and 6 in. (15 cm.) in diameter. The fluorspar or mag- 
nesite should be well vented. The charge consisted of 600 g. of 
small calcium shavings, 270 g. of minus 40 mesh aluminum 
powder and 1100 g. of 80 mesh vanadium pentoxide that had 
been freshly fused and pulverized. 

A considerable portion of the vanadium entered the slag as 
calcium vanadate, and in 8 runs the best metal was only 85 per 
cent pure. The impurities were calcium and aluminum. Remelt- 
ing the regulus from the 8 runs in an electric furnace and treating 
the melt with more vanadium oxide, removed the remaining cal- 
cium and aluminum, but the product contained a high percentage 
of vanadium monoxide. 

"Trans. Am. Electrochem. Soc., 37, 341 (1920); Jour. Ind. and Eng. Chem. 14, 
968-972. 



3o8 WILI, BAUGHMAN. 

Vogel and Tammann^^ produced vanadium metal 95 per cent 
pure by using pure dry ammonium-free vanadium pentoxide in 
the regular alumino-thermic method. The writer used the 
apparatus of Prandtl and Bleyer, described above, and 40-mesh 
aluminum dust with 80-mesh vanadium pentoxide. Out of 4 
runs the best obtained was 78 per cent vanadium metal, the 
balance was aluminum with a little vanadium monoxide. The 
point anent the oxide being pure, dry, and ammonium free is 
important. Possibly another reason why the writer was unable 
to make the same grade of vanadium that they did, is that his 
aluminum dust contained some sodium and oxygen. The sizes of 
the materials used may have been different also. 

The writer also duplicated the methods of Prandtl and Manz" 
who used vanadium trioxide instead of pentoxide for the calcium 
aluminum reduction. Vanadium trioxide gives much better 
results. There is less slag loss, and as a result of 4 runs a metal 
from 89 to 94 per cent pure was obtained, which on treating in 
the electric furnace with more trioxide gave a metal 96 per cent 
pure. Aside from the Baughman lithium method described here- 
after, the reduction of vanadium trioxide by calcium and alumi- 
num gave the best results of any method tried. 

Prandtl and Bleyer^^ also produced a 95 per cent metal by 
using 100 parts of pure, fused and pulverized vanadium pen- 
toxide, 49^ parts of aluminum powder, and 20 parts fluorspar 
in a magnesium crucible. The writer attempted to duplicate this 
but obtained only an 81 per cent vanadium metal. 

Ruff and Martin's Methods. They describe^^ three methods: 

1. Reduction of trioxide by aluminum and a small amount of 
carbon. 

2. Reduction by carbon in the electric furnace. 

3. Reduction of vanadium trioxide by vanadium carbide. 
None of these methods appealed to the author because of the 

use of carbon, as he was searching for a way of preparing a car- 
bon-free product. One run was made in a resistance furnace at 
a temperature of about 1700° C, using the third method. Ovc" 

" Z. anorg. chem. 64, 223 

^0 Ibid. 79, 209-22. 

'■ Ber. 43, 2602-3. 

*' Z. anorg. chem. 25, 39-56. 



THE METALI.URGY OF LEAD VANADATES. 309 

three-fourths of the vanadium was lost by volatiHzation of the tri- 
oxide. The regulus contained 86 per cent vanadium metal, and 
contained both carbon and oxide as vanadium monoxide. 

The writer has found that some vanadium monoxide is formed 
before decarburization is complete in any heat where decarburiz- 
ing of vanadium carbide is attempted. 

Muthmann and Weiss Method}^ This method consists of 
reduction with "misch metal," a mixture of cerium and other 
rare earth metals. The writer was unable to obtain, at the time 
of these experiments, any misch metal but did obtain some 
cerium metal. He made three 100 g. runs with the best product 
containing 84 per cent vanadium. 

Baughman's Lithium Method. Theoretically, lithium should 
be a better reducing agent than calcium, aluminum or cerium, 
as shown by the following: 

3V2O5 + lOAl = 5AI2O3 + 6V + 638,500 cal. 

3V2O5 + 15Ca = 15CaO + 6V + 648,000 cal. 

3V2O5 -f 7>4Ce =r 7i/^Ce02 + 6V + 360,000 cal. 

3V2O5 + 30Li = ISLi^O + 6V + 825,000 cal. 

This proved to be the case. The writer used lithium pellets 
about the size of BB shot in the same apparatus as was used for 
the previous experiments in calcium and aluminum reduction. 
A metal containing 95 to 97 per cent vanadium is readily obtained. 
An excess of vanadium oxide must be used, as a considerable 
amount is lost in the slag as lithium vanadate. The reduction is 
so rapid, however, that very little vanadium is lost by volatiliza- 
tion even when the trioxide is used. 

Lithium is such an expensive reducing agent that the writer 
then turned his attention to making metallic lithium from 
lepidolite, lithia mica, of which there are large deposits in Cali- 
fornia. He finally worked out a method of producing lithium 
metal within reasonable cost and was planning to use the lithium 
reduction method to produce large amounts of vanadium metal, 
when the thought occurred that vanadium oxide might be reduced 
to the metal by the same method. With minor changes the 
method was successful. It was also found applicable to reducing 

«Liebig Ann. 337, 370; 355, 58. 



3IO WILL BAUGHMAN. 

titanium, thorium, uranium, cerium, and tantalum from their 
oxides. On account of business reasons the writer cannot 
describe this method, nor the technic that he has worked out of 
using sodium vanadate, iron oxide, and metal and aluminum shot 
for producing ferrovanadium. 

Werner von Bolton's Method.-'^ This is a method of reducing 
columbium or tantalum oxides to metal. It consists in preparing 
the oxide in the form of filaments with paraffine, calcining, and 
then heating by an electric current in a high vacuum. The writer 
used vanadium trioxide, which is a conductor, but was unable to 
obtain the metal. The trioxide was reduced to monoxide and 
dioxide but not to the metal. 

The writer also attempted to produce metallic vanadium by- 
electrolysis of vanadyl salts with a mercury cathode cell, in the 
same manner that metallic chromium, tungsten and molybdenum 
can be prepared. The experiments all gave negative results. 
Vanadium does not form amalgams and in aqueous solutions 
it is always anodic in properties. 

Other methods for making metallic vanadium are those of 
Gin, Beckman and Cowper Coles. Dr. S. Fischer^^ investigated 
Cowper Coles' electrolytic method, and found it to be the forma- 
tion of a coating of platinum hydride instead of metallic 
vanadium. 

Beckman' s Method. Dr. Beckman's method^^ consisted of 
using an igneous electrolyte of fused calcium oxide, and adding 
excess vanadium oxide while passing direct current. The writer 
used the furnace described before for smelting the Black Buttes 
ore. Instead of trying to produce the metal the writer attempted 
to produce a ferrovanadium. Scrap steel weighing 50 lb. (22.7 
kg.) was first melted, then 50 lb. (22.7 kg.) of crude calcium vana- 
date charged on top and melted. At 20 min. periods for 4 hr., 
20 lb. (9 kg.) of vanadium pentoxide was added. At the end 
of thfs period the metal was tapped and cast in pigs. It con- 
tained 2.67 lb. (1.21 kg.) of vanadium metal and carbide. A 
direct current of about 500 amp. at 80 volts was used. 

Dr. Beckman gave no operating data in his paper on this 

20 Zeit. elecktrochem. 11, 4S and 722. 

=• Inst. Min. and Met. Eng. 1898-99 pp. 198-200. 

"Trans. Am. Electrochem. Soc. 19, 171 (1911). 



THE METALLURGY OF LEAD VANADATES. 3II 

method, and as apparently insignificant details determine the 
success or failure in this class of work, the writer decided to 
drop this line of investigation. 

Gin's Methods. Gustave Gin describes his two methods, in 
detail, in his "Memoir on Vanadium,"-^ to which the reader is 
referred. The first method consists of electrolyzing molten cal- 
cium and vanadium fluorides, adding vanadium tetroxide from 
time to time. The second uses a calcium and ferrous fluoride 
electrolyte, and vanadium is supplied to the bath by special anodes 
composed of vanadium trioxide and carbon. The cathodes in 
both methods are iron, copper or other metal with which it is 
desired to alloy the vanadium, or lead, which is later volatilized if 
vanadium metal is desired. This latter is an object that is diffi- 
cult to achieve. The methods are better suited for producing 
ferrovanadiuni. 

It was the writer's privilege to be Dr. Gin's assistant when he 
was developing these two processes. In modified form the second 
method was later used at the works of Paul Girod at Ungine, 
France. Technically both methods are operative, but are not in 
wide use at present because the electrically fused alumina linings 
often failed before a run was half completed. The amount 
of carbon tetrafluoride formed at the anode, while not large in 
proportion to the amount of fluorine in use in the bath, was still 
enough to require the use of tight fitting goggles and aspirators 
by the furnace operators. Instead of using calcium fluoride in 
the second method calcium vanadium fluoride, as made for the 
first process, was found necessary and the addition of tetroxide 
of vanadium was found desirable, so that the final process became 
a combination of the original two. The cost of manufacture by 
these methods is high. In fact it can not compete with electric 
furnace reduction, using silicon as reducing agent, or with the 
alumino-thermic method. 



DISCUSSION. 

B. D. Saklatwalla' : The first thing that is remarkable is 
the large number of various occurrences which the author de- 

-» Trans. Am. Electrochem. Soc. 16, 439 (1909). 
* Vanadium Corp. of America, Bridgeville. Pa. 



312 DISCUSSION. 

scribes. Vanadium is one of the most widely disseminated ele- 
ments that we know. It occurs on every continent of the globe. 
To find scattered occurrences of vanadium, therefore, should not 
appear strange, but the difficulty has been that we do not find 
them as commercial deposits. They are of an erratic nature and 
do not persist. 

Now the metallurgy of lead vanadates has not been commer- 
cially developed, not because it is a difficult problem from a 
metallurgical standpoint, but because it had no particular com- 
mercial application. 

As to the leaching methods and treatment, Mr. Baughman is 
right when he considers all these roundabout leaching processes 
as not commercial, because the losses are high. 

He then describes his method of smelting out lead, and then 
taking the slag and fusing it with sodium hydrate and making 
a sodium vanadate. I am inclined to believe that is superfluous. 
The slag that you can get by reducing the lead out of the lead 
vanadates would be perfectly amenable to reduction directly, 
either by means of aluminum or silicon, or by carbon in the 
electric furnace. So the problem of getting vanadium out of 
lead vanadates is not a difficult metallurgical problem. It has 
not been commercially exploited for the reason that there are 
no lead vanadates to exploit commercially. But at the present 
time, since the radium industry has been practically shut down 
in this country, and which was a source of vanadium obtained 
as a by-product, there has been activity in development of other 
vanadium minerals, and probably this impetus to search might 
reveal larger deposits of lead vanadates or other vanadates. 

Colin G. Fink^: Formerly all ferro-vanadium was made by 
the Goldsmith process. Dr. Saklatwalla has recently published 
a paper in the "Electrical World,"^ on the production of ferro- 
vanadium in the electric furnace. It is another ferro-alloy which 
has submitted to electric furnace methods, an alloy which for 
years has been thought impossible to produce by any but the 
alumino-thermic method. 

' Consulting Metallurgist, New York City. 

' Electric FBrnace makes Ferro-Vanadium by B. D. Saklatwalla and A. Anderson. 
Electrical World, February, 1923. 



THE METALLURGY OF LEAD VANADATES. 313 

W. C. Arsem': About sixteen years ago I made some vana- 
dium on a laboratory scale and determined the melting point to 
be 1,650° C. This was made by reducing the tri-chloride with 
magnesium, in a vacuum, similar to the classic research followed 
by Sir Henry Roscoe, who reduced the di-chloride and tri-chloride 
with sodium in hydrogen. 

Will Baughman (Communicated) : The statement that 64 lead 
vanadate deposits show commercial possibilities is not only the 
writer's opinion but is based upon reports made by competent 
mining engineers, familiar with the characteristics of the lead 
vanadates, who have examined a majority of these deposits at 
various times. 

Lead vanadates generally occur in well defined veins and 
should not be confused with carnotite or roscoelite deposits that 
occur in small, irregular, scattered pockets. To those who have 
made a study of the genesis of the lead vanadates, the probable 
existence of lead vanadate ore chutes can be determined with as 
much assurance as the probable existence of the commoner metals. 

No vanadium deposit persists in depth. All stop at the zone 
of ground waters. In the arid regions of United States this may 
mean a considerable depth. At least one lead vanadate mine 
extends to 900 ft. vertical depth, or 1300 ft. on the ore body. 
The wonderfully rich and unique deposit in the Peruvian Andes 
is no exception. In fact it is a rather shallow and superficial 
deposit, the zone of ground waters being at 100 to 150 ft. depth.^ 

The lead vanadate deposits of United States have not been 
developed, because of economic conditions, not a lack of potential 
ore. Of the several attempts made in the past to develop these 
ores all failed for reasons other than lack of ore, save one project. 

The lead vanadate miner can not ship his concentrates to some 
treatment plant. He must refine, manufacture and then market 
his product, which is a serious undertaking. 

One company owns a deposit of ore that is practically free of 
impurities, that is readily concentrated by mere roasting and 
which contained at first seven times as much vanadium as the best 
run of mine lead vanadates. Through being the first large pro- 

* Consulting Chemical Engr., Schenectady, N. Y. 

» Miller and Singewald. Mineral Deposits of South America. D F Hewett 
Vanadium in Peru. Trans. A. I. M. E. Vol. 40. 



SH DISCUSSION. 

ducers, and selling under contract systems, this company offers 
a problem in financing and competition, for which the writer 
knows no parallel. 

Before the discovery of the unique deposit owned by this com- 
pany, the lead vanadates were the principal source of supply. 
As soon as this deposit is reduced to low grade ore, so that the 
production costs will be higher than they were a few years ago, 
then the lead vanadates may again become the principal source of 
vanadium. 

Hewett's description of this property shows that the very rich 
ore occurred as shallow gash veins in a lense shaped mass 300 
ft. long, 28 ft. wide, and 200 ft. on slope to ground waters. On 
an optimistic basis this would indicate less than 100,000 tons of 
1 to 20 per cent ore, while consular reports show over 12,000 tons 
of 40 per cent concentrates have been shipped. This would 
indicate that this deposit is approaching exhaustion. Also the 
first material mined ran as high as 20 per cent vanadium oxide, 
which was raised to as high as 80 per cent by roasting. This 
roasted material has steadily fallen off in grade. Consular reports 
show that concentrated material recently shipped contained only 
16 to 20 per cent. 

During the period that the highest grade ore was being mined, 
this company sold ferro for less than $2.50 per lb. of vanadium 
content, or about $1.00 less than the writer estimated that the 
more favorably situated lead vanadate deposits could produce it. 

On the other hand, the use of vanadium may fall off. The 
same development of electric furnace practice that allows Dr. 
Saklatwalla to produce ferro-vanadium in the electric furnace, 
has also made it possible to use titanium, or other cheap nitro- 
gen and oxygen removers, and with better furnace control, pro- 
duce a steel for many purposes superior to the old vanadium 
steel. The Ford Motor Co., formerly one of the largest vanadium 
users, has used little for some time past. 

The writer did not intend to infer that he considered all the 
methods discussed in the paper as non-commercial. He considers 
the chloride volatilization method, ball mill grinding, and the 
ideas of producing 99 per cent vanadium oxide or vanadium 
metal, in order to avoid competition, as impractical. He considers 
chloridizing roasting for ores difificult to concentrate and low in 



THE METALLURGY OF LEAD VANADATES. 315 

lime or magnesia, sodimii sulfide leaching for similar ores high in 
lime or magnesia, and the smelting, refining method for concen- 
trates, as methods having excellent commercial possibilities. 

Dr. Saklatwalla suggests the direct reduction of slag, from 
smelting lead vanadates, to ferro vanadium. The lead vanadates 
all contain one or more of the elements phosphorus, molybdenum, 
arsenic, tungsten, copper, and chromium. These elements would 
enter the final product, making it worthless. Some kind of refin- 
ing system is absolutely necessary. 



A paper presented at tl\e Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 5, 1923, Dr. F. M. Becket 
in the Chair. 



PREPARATION OF METALLIC URANIUM/ 

By R. W. MooRE.2 

Abstract. 
A method for the preparation of metallic uranium in a very 
pure state is described, also a method of fusing the metal to form 
buttons or small pigs, which may be rolled down to give thin sheets. 



For the preparation of this metal in a state of high purity, the 
old method of the reduction of the anhydrous chloride with 
metalHc sodium seems to be the one giving the best results. This 
method has been used by a number of investigators, including 
Peligot,^ Zimmerman,* Moissan,' Mixter,® Roderburg,^ Fischer,^ 
and Lely and Hamburger.^ 

The method which we have used is in general that outlined by 
the last named investigators, with several modifications which 
make for simplification. As Lely and Hamburger point out, 
there are several conditions which must be fulfilled if high purity 
of the metal is to be attained. These are, in brief, the production 
of the chloride in a pure, dense form, which does not take up 
moisture rapidly. This eliminates the action of water during the 
reduction, and the attack of moist chlorides i. e., hydrochloric 
acid) on the reduction bomb. The purer the chloride, the higher 
is the temperature produced during reduction and the coarser the 
particles of metal produced. This condition is desirable since it 
results in less oxidation taking place during the removal of the 

• Manuscript received February 1, 1923. 

^ Research Laboratory, General Electric Co., Schenectady, N. Y. 

»Ann. Chim. Phys. (4,) 17, 368. 

< Ber. deutsch. Chem. Ges. 13, 348 (1882). 

"Compt. rend. 122, 1088. 

»Z. anorg. Chem. 78, 231 ri912). 

'Z. anorg. Chem. 81. I, 122. 

«Z. anorg. Chem. 81, II, 189. 

9 Z. anorg. Chem. 87, 209. 

317 



3l8 R. W. MOORE. 

other products of the reduction. If the chloride is pure the heat 
of the reaction is sufficient to fuse part of the metal product into 
the form of small pellets, 

PREPARATIOX OF THE CHLORIDE. 

The preparation of UCI4 is most easily carried out by the reac- 
tion of SoCl, on uranium oxide, (UsOg), a method similar to 
that used by Arsem^° for making ThCl^ and also used by Matignon 
and Bourion,^^ Colani/- and Lely and Hamburger.^^ An easy 
method of carrying out this reaction was found to be as follows : 
The oxide of uranium was placed in quartz or porcelain boats, 




r/G. 1 

/ ^^^/fe> at/iss rcB£. 
Z C^fff£ t/ei « 
3 //vi.£-r /^^^ ci- 

and these were inserted into a 5 cm. (2 in.) porcelain tube, 
resistance furnace. In one end of this tube, an empty boat was 
placed and redistilled SgClo was allowed to flow into this drop by 
drop through a tube connected to a separatory funnel. The other 
end of the furnace tube was closed with a rubber stopper with a 
large outlet tube opening under S^Cl, contained in a bottle. 

The furnace was inclined towards the outlet end to allow any 
excess SjCL condensing in the cool end of the tube to flow out. 
The tube was brought up to 200°-300'' C, the S^Clj started drop- 
ping in, and the temperature of the furnace gradually raised to 
500° C, at which temperature it was held for three or four hours. 
Under these conditions uranium oxide is converted to a greenish, 
coarse crystalline mass, which absorbs moisture only slowly. At 

"U. S. Patent 1,085.098. 
"Ann. Chim. Phys. (8) 5, 127 (1905). 
"Ann. Chim. Phys. (8) 12, 59 (1908). 
»» hoc. cit. 



PREPARATION OF METALLIC URANIUM. 3I9 

500° C, the UCI4 did not melt nor sublime, but remained in the 
boats in the form of a compact mass of coarse crystals. It still 
contained some oxide, and for this reason required sublimation. 

SUBLIMATION OF THE UCL4. 

An easy and convenient method of carrying out this sublimation 
was found to be as follows : A large hard glass tube, about 4 cm. 
(1.6 in.) in diam. was bent as shown in Fig. 1. The tube was 
filled with CI which was bubbled through SgClg to make sure it 
was dry. The UCI4 was emptied from the bottles, in which it 
had been sealed, directly into the tube, so as to avoid exposure to 
the air, and shaken down into the lower end of the bend. 

The outlet end was closed by a stopper carrj'ing a small tube. 
The part of the tube containing the UCl^ was heated to a bright 
red heat, with a moderate current of CI passing through it. The 
UCI4 sublimed in the form of dark red vapors, which deposited 
close to the hot zone in the form of a mass of coarse, greenish 
crystals. Besides this product, there was formed a considerable 
amount of a fluffy, golden-yellow, crystalline substance that depos- 
ited in the cooler part of the tube. This was apparently an addi- 
tion product of UCI4 with SjCl,, for on replacing the CI 
with dry N, and heating the tube containing these crystals, they 
were decomposed into UCl^ and SoClg. The UCI4 thus sublimed 
was poured directly into a bottle containing dry N, and sealed 
until it was used for reduction. 

REDUCTION. 

The sodium used for reduction was all sublimed in vacuum in 
an apparatus similar to that suggested by Lely and Hamburger.^* 
This was arranged so that the cylinder containing the sodium was 
heated in vacuum Avith the same heating arrangement as used 
later for heating the reduction bomb. See Fig. 2» 

The resublimed sodium was cut up into small pieces under 
redistilled benzol, which had stood over sodium for weeks. It 
was dried in a vacuum, and opened up under an atmosphere of dry 
nitrogen. About 25 per cent excess Na was used for the reduc- 
tion. The UCI4 was broken up into small lumps in an atmosphere 
of dry nitrogen, and this was mixed with the sodium by shaking 
in a bottle filled with dry N. 

1* Loc. cii. 



320 



R. W. MOORE. 



The reduction was carried out in a steel bomb in vacuum. The 
simplest manner of accomplishing this was to use a steel cylinder 
closed at one end, with a steel cap screwed in the other end, using 
a fine thread. A copper gasket was used under the cap, and the 
cap was screwed down by hand. This arrangement allowed the 
gas in the bomb to escape, while little or no sodium was lost dur- 
ing the reduction. The bomb was exhausted at the same time as 
the chamber in which it was heated. The arrangement for carry- 
ing out the reduction is shown in Fig. 2. 



3 c/fP aP Bo/^3 

4 CoPPsiP G^s^rr 

5 BO/^B 

7 i.ow£-J? P^^^ ar y/rct/uPf t^rsss'L. 

6 SfteSr /^'CJrft. S*^'i-i.O 

9 /JLOrvot/^ rva£ 

10 nt>--r BOS/vt/M Wf£ 

11 ^Li/^o<//^ ru3£ 

IZ /MSl/L/>r£0 TSV/^/K/liS 
/3 f/ff£ BPIC^ 

II rMfPfe ceuPi-e 
IS ^iABS^Jf sraPP£-jf 




Fig. 2 

The bomb was first filled with dry nitrogen, and the UCI4 
sodium mixture poured in and pressed down. The space above 
the charge was filled with dry nitrogen, the bomb closed up and 
placed inside the heater in the reduction chamber. This was 
exhausted to about 25 microns, and the bomb gradually heated 
until a sudden rise of temperature was shown by the pyrometer. 
The bomb was then cooled under vacuum and the vacuum broken 
with dry nitrogen. 



EXTRACTION OF THE METAL. 

The product of the reduction was a sintered grayish mass. It 
contained U, NaCl, Na, with possibly some small amounts of 



PREPARATION OF METALLIC URANIUM. 32 1 

UCI4 and uranium oxide. The excess sodium was removed with 
absolute alcohol, the NaCl completely washed out with water, and 
then the heavy brownish residue washed with dilute (2 per cent) 
acetic acid. The acid was washed out completely with water and 
the residue washed with acetone and dried in vacuum. This 
washing was carried out as rapidly as possible to avoid oxidation 
of the wet metal. It was found necessary to break the vacuum 
after the metal was dry, with dry nitrogen, for the finer portions 
of the metal were very pyrophoric. This was true to such an 
extent that the metal could not be transferred from one container 
to another without handling it entirely in an inert atmosphere, 
such as nitrogen. 

The resulting metal was a very heavy, brownish powder, con- 
taining a considerable proportion of small round sintered balls. 
The yield was usually above 90 per cent. The coarser portions 
of the metal (remaining on 80-mesh screen) were quite pure, 
analyzing as high as 99.8 per cent uranium. The finer portions 
were, of course, more affected by oxidation during the washing, 
and for this reason were not so pure. 

FUSION OF THE METAL. 

Since uranium reacts with almost all gases at high tempera- 
tures, and alloys readily with most metals, such as W, Mo, Fe, Ni, 
etc., the problem of melting or working the powdered metal into 
solid form ofifers considerable difficulty. This was finally accom- 
plished by fusing the metal on a water-cooled table with an arc in 
an atmosphere of argon at a pressure of 50 to 100 microns. The 
apparatus used for this purpose is shown in Fig. 3. 

Pellets or discs of two sizes (about 2.5 cm. and 3.75 cm. diam. 
and 0.5 cm. thick) were made by pressing the powdered metal in 
a mold using a hydraulic press. In order to prevent spontaneous 
ignition of the metal, the mold was filled with N and the metal 
powder poured into the mold through a stream of N. After 
pressing, the metal no longer took fire, but the discs were pre- 
served in an atmosphere of dry N to prevent oxidation. 

The large discs were clamped in the upper electrode, in the 
apparatus shown, and the smaller placed on the water-cooled 



322 



R. W. MOORE. 



table ; usually two discs were used, placed one on top of the other. 
The large discs were first sintered by placing on the table and 
passing an arc over them. 

After the air had been exhausted from the globe to 0.5 micron, 
the globe was washed out by passing in argon to a pressure of a 
few mm. and again exhausted. Then the globe was filled with 
argon at a pressure of about 75 to 100 microns, an arc started by 
in contact with the discs on the table, and then the arc was moved 




6 &t.^ss at/4, a 



Fig. 3. 



pushing down on the upper electrode to bring the disc of uranium 
around over the surface of the discs by manipulating the upper 
electrode. In the course of one or two minutes the surface of the 
discs could be all brought to fusion. The discs were then cooled, 
turned over on the table, and the other side fused as before. By 
using care not to keep the arc on too long, the whole pellet could 
be melted, provided too much oxide was not present. In most 
cases, there was sufficient oxide present to prevent complete 
fusion ; the oxide appeared to be very difficult to fuse. 



PREPARATION OF METALLIC URANIUM. 323 

In order to obtain metal nearly free from oxide, a depression 
was cut in the water-cooled table, the metal discs were placed on 
the edge of this, and the melted uranium caused to run out of 
the unfused portion of the discs into the depression by tilting the 
table slightly. If the table were made thin and kept well cooled, 
the melted uranium solidified immediately in the depression 
without attacking the metal of the table, which was made of iron 
or monel metal. The small pigs of metal formed in this way 
were at times remelted on a smooth table to form fiat smooth 
buttons. 

PROPERTIES OF METALLIC URANIUM, 

The metal thus formed had about the appearance of polished 
iron. It oxidized quite readily ; a brightly polished piece became 
tarnished quite brown when exposed to air for two or three days. 
The metal was very ductile ; some buttons formed as above were 
rolled cold from a thickness of about 5 mm. to small sheets about 
0.375 mm. (0.015 in.) thick. 



DISCUSSION. 

Chas. a. Doremus^: I desire to call the attention of the 
Society to the fact that Fig. 3 is substantially Robert Hare's elec- 
tric furnace, invented in 1842, and which was described to this 
Society some years ago, and later by Edgar F. Smith in his book 
on "Chemistry in America." 

In Hare's furnace, the top electrode was movable. He made a 
great many interesting experiments. It was unquestionably the 
first electric furnace in this country, if not in the world. 

J. W. Harden and H. C. Rentschler^ : This paper is of great 
interest to us, since we are interested in the preparation and prop- 
erties of certain rare metals. This discussion is intended to bring 
out some additional questions and difficulties which are found 
during the preparation of the extremely active element uranium. 

1 New York City. 

'Research Lab., Westinghouse Lamp Co.. Piloomfield, N. J. 



324 DISCUSSION. 

We have many samples of uranium powder by practically all of 
the methods now given in the literature, and we are thoroughly 
familiar with the process used by Mr. Moore. 

We do not agree that the reduction of the chloride with metallic 
sodium is the method which gives the best results for the prepara- 
tion of uranium or indeed of some other metals, such as thorium, 
zirconium, etc. Burger,^ for example, in 1908 describes the 
reduction of uranium oxide with calcium, in which he claims a 
high degree of purity. This is the same method which was used 
in 1904 by Huppertz^ for other rare metals. The advantage of 
using uranium oxide in place of uranium chloride if it can be 
satisfactorily reduced is obvious, since the difficulty of the prepara- 
tion of the pure dry chloride is costly, tedious and difficult. The 
chloride must be distilled at high temperatures, and even under 
the most exacting of conditions it seems almost impossible to 
avoid traces of oxy-chlorides and also contamination from silica. 

In the reduction of the chloride with sodium, if there is any 
trace whatever of moisture of oxy-chloride where oxide can be 
formed, the sodium will not reduce the oxide. It is therefore 
next to impossible to get 100 per cent uranium, that is, as metallic 
uranium free from uranium oxide in this way. 

Mr. Moore states in his paper that his uranium powder was 
brown. We all know that molybdenum powder or tungsten pow- 
der or other metal powders when in reasonably coarse condition 
as Mr. Moore's probably was, are gray and not brown. The 
brown color indicates the presence of considerable amounts of 
oxide. It is possible to have a sample of uranium powder which 
will analyze a high percentage of total uranium, but which will 
also, if figured in terms of oxide, show a considerable amount of 
uranium oxide present, or a much lower percentage of free metal- 
lic uranium than of total uranium. This is due, of course, to the 
high atomic weight of uranium and the low atomic weight of 
oxygen. We should like to ask, therefore, if Mr. Moore actually 
determined the percentage of oxygen or uranium oxide in this 
sample. Our experience indicates to us that a sample of uranium, 
of the coarseness indicated by Mr. Moore, would have a consid- 

* Burger; Dissertation, Basel (1908). 
Mluppertz, Chem. Cent. 1, 1383 (1904). 



PREPARATION OF METALLIC URANIUM. 325 

erable percentage of oxide if it had much of a brown color, per- 
haps 10 or 20 per cent of oxide figured as UgOs, or a much larger 
percentage figured as a lower oxide. We have made many sam- 
ples of this kind. 

We should also like to inquire whether the percentage of iron 
has been determined. Mr. Moore has given no data in his paper 
with regard to the iron content of his uranium sample, which we 
understand was made in an iron bomb. Fisher and RideaP and 
others have found that with the chloride method of reduction, 
the uranium thus produced contains a considerable amount, say 
from 0.5 to 2 per cent of iron. We should like to know if the 
iron has been actually determined, since this has important bear- 
ing on the methods of determining the purity of uranium and 
its apparent melting point. If there is much iron present, and the 
percentage or uranium metal is determined by simply burning to 
oxide and getting the increased weight, the larger increase due 
to the presence of a small amount of iron would make up for the 
presence of a considerable amount of uranium oxide in the sample. 

Furthermore, we should like to know the melting point of the 
buttons which Mr. ]\Ioore has prepared by arc-melting on pieces 
of monel metal. We infer from his paper that the melting point 
of the beads is fairly low, and should like to point out that when 
the reduction is carried out in an iron bomb, there is no difficulty 
in getting a powder which consists, partly at least, of little beads 
of apparently fused metal. This is not the case if the presence of 
iron is excluded. 

It is hoped that a paper can soon be published describing meth- 
ods by which uranium powder is now being produced in the Re- 
search Laboratory of the Westinghouse Lamp Company, which, 
as has been stated, is not brown but has the appearance and the 
fine pressing quality of a good sample of molybdenum powder. 
This kind of uranium powder can be pressed into any desired 
shape, and with proper precautions against oxidation and spon- 
taneous combustion in the air can be sintered, treated into bars or 
into solid buttons of any desired shape suitable for example for 
X-ray targets or other commercial purposes. 

In conclusion, the present writers have worked with the method 

3Z. anorg. Chem. 81, 170, (1913). 



326 DISCUSSION. 

described by Mr. Moore, but were not able to obtain samples of 
uranium powder by any means free of oxide. It is character- 
istic of uranium, if it contains even very small quantities of almost 
any kind of metallic impurities, that when heated in a vacuum or 
in an inert environment beads of low melting point metal separate 
and run away from the remainder of the mass. We experienced 
considerable trouble in finding a suitable substance upon which 
to support uranium during its heat treatment. Uranium alloys 
with most metals, (even tungsten) under proper conditions, and 
interacts with such refractories as lime, magnesia, etc. We have 
devised a method for making pure thorium oxide crucibles, which, 
when properly heat treated, have served excellently for this 
purpose. 

R. W. Moore (Communicated) : In reply to the point raised by 
Dr. Doremus, I would say that there was no intention of even 
suggesting that this type of furnace is new. Similar furnaces 
have been used for various purposes in the past. The present 
paper simply shows the application of this type to this particular 
problem, with some details modified to fit this case. The method 
of separating the metal from the oxide and obtaining a small 
pig of pure cast metal is believed to be new. 

Messrs. Marden and Rentschler bring out several points on 
which there may be differences of opinion. As regards the rela- 
tive values of the methods of reduction by calcium and sodium, 
much may be said. It would seem that the reduction products 
from the sodium reduction, namely NaCl, excess Na, and possibly 
undecomposed UCI4, should be much more easily extracted from 
the uranium metal than the CaO and possibly undecomposed ura- 
nium oxide produced during the reduction by calcium. In the 
case of thorium, with which we tried both methods, the sodium 
reduction gave the best results. 

In regard to the difficulty of preparing the UCI4, I do not agree 
with Messrs. Marden and Rentschler. It is not particularly costly, 
nor tedious, and certainly not difficult. It does require care. The 
sublimation does not require high temperature ; it is readily carried 
out in a hard glass tube. 



PREPARATION OF METALLIC URANIUM. 327 

Messrs. Marden and Rentschler state that the brown color of 
the powdered uranium metal indicates the presence of considerable 
amounts of oxide. Unquestionably, the color indicates oxidation 
of the surface of the particles. Uranium is quite easily oxidized ; 
as mentioned in the paper, even rolled and worked metal pieces, 
when polished bright will turn quite brown in a few hours in the 
air. Naturally, during the process of washing out the NaCl, Na, 
etc., from the reduction mass, the metal is constantly subject to 
oxidation, and the particles tarnish, but probably only on the sur- 
face, since the particles are dense, and the oxygen probably does 
not penetrate to any appreciable depth. Since our analyses show 
a percentage of uranium as high as 99.8 per cent this would seem 
to be the case. Of course, the 0.2 per cent oxygen (assuming the 
difference to be all oxygen) may mean several per cent of oxide. 
The fact that there was some oxidation of the particles was the 
reason for the process described in the paper of melting the 
metal away from the oxide coating. The fact that the metal so 
obtained was very ductile would seem to indicate that it was quite 
well freed from oxide. 

It would seem that any process of reduction would be subject 
to this difficulty of oxidation of the metal during extraction of 
the reduction products. If Messrs. Marden and Rentschler have 
found some method of avoiding this I shall be interested to learn 
what it is. 

In regard to the possible content of iron in the uranium, I would 
refer to the paper by Messrs. Lely and Hamburger,® in which they 
state that if the uranium chloride (and also thorium chloride) 
is kept dry, there is no trace of iron in the metal produced in the 
steel bomb. We did not analyze our metal for iron, there being 
no reason to expect contamination from this source. After many 
reductions, the bomb used showed no sign of any attack by the 
reduction materials. Furthermore, in cases where a small amount 
of iron had alloyed with the melted metal during fusion of the 
pellets in the furnace described, the resulting alloy was very 
brittle. The metal we obtained was very ductile. This would 
indicate the absence of any considerable amount of iron. Although 

« Z. anorg. Chem.. 87, 209. 



328 DISCUSSION. 

we have no positive evidence that traces of iron may not have 
been present, the indications are that it was probably not present 
Amounts such as suggested by Messrs. Harden and Rentschler 
are entirely out of the question. 

The melting point of the metal produced by the method 
described in the foregoing paper has not as yet been definitelv 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City. May 5, 1923, Dr. F. M. Becket in 
the Chair. 



EXPERIMENTS RELATIVE TO THE DETERMINATION OF URANIUM 
BY MEANS OF CUPFERRON.' 

By Jas. a. Holi.aday and Thos. R. Cunningham.^ 

Abstract. 

A description is given of experimental work concerning the 
determination of uranium by precipitation with cupferron. Data 
are cited to prove that quadrivalent uranium can be quantitatively 
precipitated by cupferron from solutions containing from 4 to 8 
per cent of H.SO^ (sp. gr. 1.84), that aluminum, calcium, mag- 
nesium and phosphorus remain in solution and can be completely 
separated from the uranium by filtration, and that the precipitate 
of UCCeHsN.O-,)^ can be quantitatively converted to U.O, by 
ignition. 



PRELIMINARY REMARKS. 

Recent years have witnessed a marked increase in interest con- 
cerning uranium, and in experimental work looking to the dis- 
covery of new uses for its compounds and alloys. Coincident with 
and resulting directly from this activity there has arisen a need 
for more satisfactory analytical methods for the determination 
of the element. Without going into an exhaustive discussion of 
the present state of the art, it may be stated that although several 
of the commonly used methods are capable of yielding accurate 
results, the necessary separations are accomplished by reactions 
requiring numerous time-consuming and laborious re-precipita- 
tions, particularly the separation of uranium from vanadium and 
of uranium from aluminum. The experimental work described 
in this paper had for its object the development of a procedure 

' Manuscript received January 11, 1923. 

a Union Carbide and Carbon Research Labs., Inc., Long Island City, N. Y. 

22 329 



330 JAS. A. HOLLADAY AND THOS. R. CUNNINGHAM. 

free from these objections, /. e., one based on sharp, clean-cut 
reactions. 

It has been shown by W. A. Turner* that vanadium can be 
quantitatively separated from uranium, phosphorus, and arsenic 
by precipitation with cupferron in a 10 per cent sulfuric acid 
solution. Under these conditions aluminum, calcium, magnesium 
and phosphorus, impurities usually found in carnotite, pass 
quantitatively into the filtrate, while iron (titanium and zirconium) 
is completely precipitated wuth the vanadium. The reliability of 
these separations has been confirmed in this laboratory. Recently 
V. Auger* has gone on record to the effect that quadrivalent 
uranium can be quantitatively precipitated from an acid solution 
by cupferron as a brown, flocculent precipitate having the formula 
U(C6H5N202)4. However, this article makes no mention of 
the necessary acidity nor of the behavior of aluminum, calcium, 
magnesium, zinc and phosphorus. Believing that these reactions 
might prove to be better suited to the separation and determina- 
tion of uranium and vanadium than any previously proposed, 
experiments were carried out to obtain information on the fol- 
lowing points. 

1. To confirm Auger's statement that quadrivalent uranium is 
precipitated by cupferron in acid solutions, and to find out 
whether uranium is also precipitated when present in a still lower 
state of oxidation than U^^. 

2. To determine within what limits of acidity the precipitation 
is complete. 

3. To learn whether the uranium precipitate, UCCgHsNoO,)*, 
can be quantitatively converted to UgOg by ignition. 

4. To ascertain whether aluminum, calcium, magnesium, phos- 
phorus, and zinc can be quantitatively separated from uranium 
by proper regulation of the acidity. 

PREPARATION OF STANDARD SOLUTIONS. 

In order to carry out the proposed study of the reactions, the 
following standard solutions were prepared: 

1. Uranyl Sulfate, UOz{SO^)o, Solution. Prepared by dis- 
solving 1.2 grams of the C. P. salt in water and making the solu- 

'Am. J. Sci. 42, 109-10 (1916). 
«Compt. Rend.. 170. 995-6 (1920). 



THE DETERMINATION OF URANIUM. 331 

tion up to 500 cc. in an accurately calibrated 500 cc. volumetric 
flask. If the uranyl sulfate, UOaCSOJ^. had been pure, 100 cc. 
of the solution should have contained 0.1237 g. of uranium. The 
actual uranium content was determined by the following three 
methods : 

(a) Precipitation as (NHJ2U2O7 and Weighing as UgOs- 
The uranium in a 50 cc. aliquot part of the solution was precipi- 
tated with ammonium hydroxide^ and ignited to UsOg. The 
weight of the precipitate of UgOs was 0.0750 g., corresponding to 
0.1272 g. U in 100 cc. of the solution. 

(b) Precipitation as (NHJ2UO3V2O5 . HgO and Weighing as 
2UO3 . V2O5. The uranium in a 25 cc. ahquot part of the solution 
was precipitated as ammonium uranyl vanadate, and ignited and 
weighed as 2UO3 . V2O5 according to Blair.« The result obtained 
by this method was 0.1276 g. of U in 100 cc. of the solution. 

(c) Reduction with Zinc and Titration with 0.1 N KMn04. 
A 50 cc. aliquot part of the solution was acidified with 6 cc, of 
H2SO4 (sp. gr. 1.84), diluted to 100 cc. cooled to room tempera- 
ture, and passed through a Jones reductor having a zinc column 
about 25 cm. (10 in.) long. The uranium was completely removed 
from the reductor by the use of 125 cc. of water. Approximately 
six minutes were consumed in passing the solution and washings 
through the reductor. When the amount of uranium to be 
reduced exceeds about 0.3 g., a preliminary reduction in the 
beaker with 5 g. of zinc is necessary. The solution was vigor- 
ously stirred for 1.5 minutes to re-oxidize the small amount of 
uranium reduced below the uranous (11(804)2) state, and 
titrated with 0.1 A/" KMn04 that had been standardized against 
Bureau of Standard's sodium oxalate. By this procedure the 
result 0.0631 U in 50 cc, or 0.1262 in 100 cc, was obtained. 

A resume of the results obtained by the three methods follows : 

Grams U in 100 cc. 

Amount theoretically present 0.1237 

Amount found by weighing UsOs 0.1272 

Amount found by weighing 2110.3. V20:i 0.1276 

Amount found by zinc reduction 0.1262 

Average 0.1270 

» C. A. Pierle, J. Ind. and Eng. Chem., 12, 1, 60. 
• "Cliemical Analysis of Iron," ji. 210. 



332 JAS. A. HOLLADAY AND THOS. R. CUNNINGHAM. 

2. Sodium Vanadate Solution. Prepared by covering 2 g. of 
pure VoOj with hot water, and adding Na202 in small amounts 
until the VjOj had dissolved. The resulting solution was boiled, 
filtered, and made up to 500 cc. in a volumetric flask. If the 
V2O3 had been pure the vanadium value of 100 cc. of the solution 
should have been 0.2240 g. A determination made of a 25 cc. 
aliquot part of the solution by reduction with H2O2 in concentrated 
sulfuric acid solution, followed by titration with 0.1 A/" KMn04 
(Cain and Hostetter's method) yielded the result 0.2020 g., while 
another determination made by passing a 25 cc. aliquot portion, 
acidified with 6 cc. of H2SO4 (sp. gr, 1.84) and diluted to 100 cc, 
through a Jones reductor into ferric phosphate solution and 
titrating with 0.05 A^ KMn04, gave an identical result. 

3. Phosphorus Solution. Prepared by dissolving 0.1065 g. of 
ammonium phosphate, (NH4)2HP04, in 250 cc. of water in a 
volumetric flask. The phosphorus content of a 25 cc. aliquot part 
of this solution was determined by precipitating with "molybdate 
solution" and filtering and washing the ammonium phospho- 
molybdate. The "yellow precipitate" was subsequently dissolved 
in NH4OH, acidified with H2SO4, and the resulting solution 
passed through a Jones reductor into ferric phosphate solution 
and titrated with a solution of KMn04 (1 cc. =r 0.0000431 g. P) 
that had been standardized against Bureau of Standards sodium 
oxalate. The actual phosphorus value of the solution was found 
to be 0.000114 g. per cc. as against the theoretical of 0.0001 g. 

4. Aluminum Solution. Prepared by dissolving 8.9 g. of 
ALClg . I2H2O in water, adding H2SO4, evaporating until all free 
H2SO4 had been expelled, dissolving in water, and filtering and 
making up to 500 cc. in a volumetric flask. One hundred cc. of 
the solution was found to contain 0.2014 g. of aluminum. 

5. Calcium and Magnesium Sulfates. In the experiments 
where known amounts of calcium and magnesium were added 
weighed amounts were employed of the c. p. salts, CaS04 . 2H2O 
and UgSO, . 7U,0. 

GENERAL DESCRIPTION OF EXPERIMENTS. 

"Synthetic" solutions containing known amounts of one or 
more of the elements under consideration — uranium, vanadium, 



THE DETERMINATION OF URANIUM. 333 

aluminum, calcium, magnesium, phosphorus and zinc — were pre- 
pared by measuring with accurately calibrated pipettes aliquot 
portions of the standard solutions or in a few instances (calcium 
and magnesium) by weighing the salts. When vanadium was 
present, the "synthetic" solution (volume 100 cc.) was acidified 
with 12 cc. of H2SO4 (sp. gr. 1.84), treated with enough 
KMn04 (approximately 0.1 A'') to give a permanent pink color, 
and cooled to 10° C. The vanadium was precipitated by addition 
of an excess of a cold 6 per cent solution of cupferron and the 
precipitate (mixed with paper pulp) was filtered and washed with 
cold 10 per cent HoSO^ containing 1.5 g. of cupferron per L. 

If the determination of vanadium was a part of the program, 
the paper holding the cupferron precipitate was dropped into an 
Erlenmeyer flask, and treated with 30 cc. of HjSO^ (sp. gr. 1.84) 
and 10 cc. of HNO3 (sp. gr. 1.42) and evaporated to fumes. 
After several successive evaporations with 10 cc. portions of 
HNO3 to destroy carbonaceous matter and one evaporation with 
10 cc. of water to expel every trace of HNO.,, the vanadium was 
reduced with H.O, and titrated with 0.05 N KMnO^ (Cain and 
Hostetter's method). The filtrate from the cupferron precipitate 
was evaporated to a volume of about 50 cc, 20 cc., of HNO... 
(sp. gr. 1.42) were added, and the evaporation was continued 
until clouds of sulfur trioxide were evolved. A second evapora- 
tion with HNO3 was made to destroy all organic matter, and the 
solution was finally evaporated with 10 cc. of water to remove 
all HNO3. The solution was then diluted with the volume of 
water necessary to give the desired acidity — for example, 137 cc. 
of water if 8 per cent acidity was desired — cooled to room tem- 
perature, and passed through a Jones reductor in the manner 
previously described, the reductor then being washed with 100 cc. 
of the same strength (8 per cent in the example cited) sulfuric 
acid. The quadrivalent uranium solution was finally cooled to 
5°-10° C. and treated with an excess of a freshly prepared 
6 per cent solution of cupferron. 

The precipitate does not begin to form until from 5 to 10 cc. 
of cupferron have been added. Some ashless paper pulp was intro- 
duced and the brown precipitate was filtered on an 11 cm. paper. 
The precipitate of U(CH..N202)4 was washed with cold 5 per 
cent H2SO4, containing 1.5 g. of cupferron per L., and ignited in 



334 JAS. A. HOLLADAY AND THOS. R. CUNNINGHAM. 

a weighed platinum crucible, first at a low temperature and then 
at 1000-1050° C. in an electric muffle furnace into which a cur- 
rent of oxygen was passed. The crucible and precipitate were 
then cooled and weighed and the amount of uranium was cal- 
culated from the weight of UgOg. As a check on the gravimetric 
method the precipitate was fused with K2S2O7, dissolved in 100 
cc. of 6 per cent H2SO4, and the uranium determined by passing 
the cold solution through a Jones reductor and titrating with 0.1 
N KMnOi as previously outlined. 

Experience indicated that high uranium results are always 
obtained when uranium oxide (or ammonium di-uranate) is dis- 
solved in HNO3, and evaporated to fumes with H2SO4, prelimi- 
nary to reduction with zinc and titration with KMnO^. Addition 
of water and evaporation to fumes a second time does not 
eliminate the error, which is apparently due to obstinate retention 
of nitric acid by the uranium compound and subsequent reduc- 
tion of the nitrate to hydroxylamine, NH2OH, which is oxidized 
by KMn04. Uranium compounds should therefore be dissolved 
in H2SO4, or fused with K2S2O7 and dissolved in H2SO4, rather 
than dissolved in HNO3 and evaporated with H2SO4, as a pre- 
liminary to passage through the Jones reductor. 

When elements such as aluminum, phosphorus, etc., were 
present in the "synthetic" solutions, the filtrate from the 
U(C6H5N202)4 was evaporated with HNO3 as already described, 
and the elements in question were determined by the usual 
methods. 

1. Experiments to Determine Whether Uranium in the Quadri- 
valent Form or in a Still Lower State of Oxidation is 
Quantitatively Precipitated by Cupferron. 

The factors that were kept constant in these experiments were : 

1. The amount of uranium present, 0.0842 g. in each case. 

2. The volume and acidity. In each experiment 100 cc. of the 
solution containing 6 cc. of H2SO4 (sp. gr. 1.84) were passed 
through the reductor, which was then washed with 100 cc. of 6 
per cent H2SO4. The uranium was therefore precipitated from a 
solution having a volume of 200 cc. and containing 12 cc. of 
H2SO4 (sp. gr. 1.84). 



THE DETERMINATION OF URANIUM, 



335 



3. Time of passage of solution and washings through redac- 
tor, about six minutes. 

The conditions that were varied were : 

1. The temperature of the solution passed through the reduc- 
tor. In Experiments Nos. 1 and 2 the solutions were at room 
temperature, while in No. 3 the solution was heated to boiling 
previous to reduction to increase the amount of uranium reduced 
below the quadrivalent form. 

2. In Experiment No. 2 the solution was given a preliminary 
reduction with 2 g. of zinc before being put through the reductor, 
the object being to reduce as much uranium as possible to a lower 
state of oxidation than the quadrivalent form. Similarly, in 
Experiment No. 1 the reduced solution was vigorously stirred for 
three minutes before precipitating the uranium with cupferron, 
while in Experiments 2 and 3 the uranium was precipitated 
immediately after the reduction. 



Expt. 
No. 



Acid- 
ity 
Per 

Cent. 



Weight of U 
Used 



0.0842 
0.0842 
0.0842 



Weight of U Found 

by Weighing 

the UaOs 



0.0843 
0.0840 
0.0844 



Weight of U Found 

by Zn Reduction 

and KMnOi 

Titration 

g. 



0.0842 
0.0835 
0.0837 



These results constitute reasonably conclusive evidence that : 

1. Auger's statement that quadrivalent uranium can be quan- 
titatively precipitated with cupferron is correct. 

2. That uranium present in a lower state of oxidation than the 
quadrivalent form is also precipitated. 

3. That the precipitation can be made in a solution contain- 
ing 6 cc. of H2SO4 (sp. gr. 1.84) per 100 cc. 

4. That when the precipitation is made from a solution con- 
taining 6 cc. of H,SO, (sp. gr. 1.84) per 100 cc. the presence of 
zinc sulfate does not lead to any contamination of the 

U(CeH,NA)4. 

5. That the precipitate of UCCeHsNoO.)^ can be quantitatively 

converted to U.O,. 



336 



JAS. A. HOLIvADAY AND THOS. R. CUNNINGHAM. 



The following two additional experiments furnish further con- 
firmation of the above statements and also illustrate the separa- 
tion of uranium from vanadium : 



Expt. 

No. 


1 
Acid- Weight of U 
Pe^ Used 
Cent. ^• 


Weight of U 

Found by 

Weighing 

the UjOg 

g- 


Weight of U 

Found by 

Zn Reduction 

and KMnO* 

Titration 

g. 


Weight of 

Used 
g> 


Weight of 

V 

Found 

g- 


4 

S 


6 
6 


0.0127 
0.1270 


0.0124 
0.1264 


0.0123 
0.1262 


0.1300 
0.0260 


0.1295 
0.0260 



2. Experiments to Determine Within What Limits of Acidity 
the Precipitation is Complete. 

The experiments already cited under (1) show that complete 
precipitation is obtained from a solution containing 6 cc. of 
H2SO4 (sp. gr. 1.84) per 100 cc. and the results of experiments 
shown under (4) prove that an acidity as high as 8 per cent can 
be successfully employed. Qualitative tests showed that when 
the concentration of H2SO4 was increased much above 8 per cent 
the uranium is not completely precipitated. Inasmuch as the 
results of the experiments shown under (4) prove that sharp 
separations from the accompanying impurities can be obtained in 
a 6 per cent H2SO4 solution, there is no reason for using higher 
concentrations than 6 per cent or 7 per cent. 

3. Experiments to Determine Whether the Uranium Precipitate, 
U{CQHr^No0.j)i, Can be Quantitatively Converted to U^O^ 

by Ignition. 

The results of numerous experiments tabulated under 1, 2 and 
4 prove that the precipitate can be quantitatively ignited to UaOs- 

4. Experiments to Determine Whether Aluminum, Phosphorus, 
Calcium and Magnesium can be Quantitatively Separated 

from, Uranium by Proper Regulation of the Acidity. 

(See Table on next page.) 

Experiments 6 and 7 show that if the acidity is reduced as low 
as 2 per cent or 3 per cent the uranium precipitate drags down 
aluminum and probably phosphorus, while Experiment 8 proves 



THE DETERMINATION OF URANIUM. 



337 



that a sharp separation of uranium from aluminum and phos- 
phorus is obtained with an acidity of 4 per cent. Experiments 
9 and 10 show that uranium can be- quantitatively precipitated 
from a 6 per cent H2SO4 solution, and that aluminum is not 
carried down, while Experiments 11 to 14 inclusive illustrate the 
separation from aluminum, calcium, magnesium, and phosphorus 
under similar conditions. Experiments 15 and 16 prove that the 
precipitation of uranium is complete with an acidity of 8 per cent. 





Acid- 


Kxpt. 


ity 


No. 


Per 




Cent 


6 


2 


7 


3 ' 


8 


4 


9 


6 


10 


6 


11* 


6 


12* 


6 


13* 


6 ; 


14* 


6 


15* 


8 


16 


' i 



Added 



Uranium 



Found 

as 
UtOg 

8- 



\'anadiuin 



Phosphorus 



0.210s 

0.2105 
0.1684 
0.0318 
0.0635 
0.0635 
0.0635 
0.4210 
0.2105 
0.4210 
0.1684 



Found 
with Zn 

and 
KMnO* 

8' 



Added 
8- 



Found 
g* 



Added 
g. 



Found 
g- 



Wt. of 

AI2O3 
Added 
g- 



0.2188 
0.2137 
0.1679 
0.0316 
0.0628 
0.0625 
0.0636 
0.4210 
0.2103 
0.4208 
0.1688 



0.2108 
0.2097 
0.1675 
0.0314 
0.0622 
0.0624 
0.0628 
0.4194 
0.2100 
0.4200 
0.1681 



0.00057 

0.00057 
0.00114 



0.0260 
0.1300 
0.1010 
0.0202 



0.0260 

0.1622 ; 

0.0203 



0.00114 

0.00342 
0.00285 
0.00285 
0.00285 
0.00114 



0.1140 

0.1140 

0.00114 0.1980 
0.0760 
0.1885 
0.1885 
0.1885 
0.1885 
0.1885 
0.0580 
j0.1980 



0.00112 
0.00340 
0.00284 
0.00288 
0.00285 
0.00116 



• In experiments 11 to IS inclusive there were present in addition to the elements 
shown in the tabulation 0.05 g. CaO and 0.03 g. MgO. Zinc sulphate was of course 
present in all of the experiments. 



Experiments 11 and 12 also illustrate the accuracy of the separa- 
tion of vanadium from uranium, aluminum, calcium, magnesium, 
and phosphorus. 

The following tabulations show the averages of the uranium 
and vanadium results obtained in the entire series of experiments 
excepting Nos. 6 and 7. 

Uranium 

Average weight used 0.1431 g. 

Average weight found by weighing the UaOs 0.1429 g. 

Average weight found by Zn reduction and KMn04 titration. 0.1424 g. 

Vanadium 

Average weight used 0.0606 g. 

Average weight found 0.0608 g. 

23 



338 JAS. A. HOLLADAY AND THOS. R. CUNNINGHAM. 

CONCLUSIONS. 

Study of the results of these experiments leads to the following 
conclusions : 

1. Quadrivalent uranium, or uranium in a lower state of oxi- 
dation than the quadrivalent form, can be completely precipitated 
with a freshly prepared solution of cupferron from solutions con- 
taining from 2 to 8 cc. of H2SO4 (sp. gr. 1.84) in 100 cc. 

2. The precipitate can be quantitatively converted to U3O, by 
ignition. 

3. If the amount of sulfuric acid in the solution is less than 
4 cc. per 100 cc, aluminum, and probably phosphorus, will be 
carried down with the uranium, while if the acidity exceeds 8 cc. 
the uranium will not be completely precipitated. If the acidity be 
maintained between 4 and 8 per cent (preferably at about 6 per 
cent) a sharp separation of uranium from aluminum, zinc, calcium, 
magnesium, and phosphorus can be obtained by a single precipita- 
tion. 

A large amount of convincing data has been presented to prove 
that uranium and vanadium can be separated and determined with 
a satisfactory degree of accuracy in the presence of widely vary- 
ing amounts of iron, aluminum, calcium, magnesium and phos- 
phorus, by a process involving the following steps : 

1. Precipitation of the vanadium and iron from a 12 per cent 
H.SO4 solution in which the uranium, vanadium, and iron are 
present in the higher states of oxidation, vis., in the sexivalent, 
pentavalent and trivalent forms. Uranium, aluminum, calcium 
(unless present in amount sufficient to precipitate out as the 
difficultly soluble CaSO^), magnesium, and phosphorus pass quan- 
titatively into the filtrate when the solution is filtered. Vanadium 
can be determined in this precipitate by any of the usual methods. 

2. Destruction of the cupferron by evaporation of the filtrate 
with nitric acid. 

3. Reduction of the uranium by passage of the solution 
through a Jones reductor. The zinc sulphate introduced into 
the solution does not interfere with the subsequent reactions. 



THE DETERMINATION OF URANIUM. 339 

4. Precipitation of the uranium from a 6 per cent H0SO4 solu- 
tion with cupferron, followed by filtration and washing to remove 
aluminum, zinc, calcium, magnesium and phosphorus. 

5. Ignition of the uranium precipitate to UsOg. After having 
weighed the UgOg, its uranium content may be checked by fusing 
it with K2S2O7, dissolving the fusion in H2SO4, and passing the 
solution through a Jones reductor and titrating it with 0.1 N 
KMnO,. 

The reactions upon which this method is based are more sharp 
cut and dependable than any other with which the writers are 
familiar. The procedure has been applied to the analysis of 
uranium and vanadium ores and alloys with excellent results. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 4, 1923, President Schlueder- 
berg in the Chair. 



COBALT— ITS PRODUCTION AND USES.* 

By C. W. Drurv.2 

Abstract. 

In the preparation of the following paper dealing with the 
production and uses of the metal cobalt, an attempt has been made 
to review only the essential points. An extensive study of the 
occurrences, metallurgy, uses, and alloys of the metal cobalt was 
published recently,^ and the reader is referred to that report 
for any detailed information. 



In Table I is given the production of cobalt ores in the various 
countries. The figures in the table are interesting since they 
show the history of the mining of cobalt. The deposits of cobalt 
were small and often the metal w-as obtained as a by-product. 
Austria was the first large producer, followed by Germany, Nor- 
way and Sweden, Spain, Germany, New Caledonia and Canada. 
The consumption of cobalt compounds has gradually increased 
from that sufficient to supply the pottery industries of Europe, 
which would perhaps be approximately 10 tons in 1860, to a 
world's supply of 400 tons in 1920. The use of cobalt compounds 
for coloring glass has been known by the Chinese for perhaps 60 
or 75 years. No record is available of the production, but it 
must have been small. At present the Chinese import cobalt 
supplies from America. A few remarks summarizing the metal- 
lurgy of cobalt have been incorporated in the paper. 

In Table II a list of the commercial compounds of cobalt, show- 
ing the range in cobalt content, has been prepared. 

' Manuscriot received February 24, 1923. 

' Professor of Metallurgical Research, Queen's University, Kingston, Ont. 

' Report of Ontario Bureau of Mines, XXVII, Part 3, 1918. 

341 



342 



C. W. DRURY. 



ORES. 

The mining of cobalt ores has been carried on in Europe for a 
considerable time but no records of production are available pre- 
vious to 1856. With the discovery of the cobalt deposits in 
Canada in 1903, the mining of cobalt ores in Europe and New 
Caledonia practically ceased. The mining of cobalt ore flourished 
best previous to 1860, in Austria, in Germany between 1872-1876 
and 1889-1893, in Norway from 1877 to 1893, in Sweden 1876- 
1893, and in New Caledonia between 1893 and 1908. 

Cobalt ores are usually associated with nickel, iron, copper, 
and silver minerals. Bismuth, antimony, arsenic, sulfur, man- 
ganese and lead are also often present. 

The ore of New Caledonia is a hydrated oxide of manganese, 
cobalt and nickel, high in iron. The ores of West Australia are 
practically free from nickel. In Africa at the Union Miniere du 
Haut Katanga, cobalt is associated with copper. In the United 
States at Fredericktown, Missouri, nickel, copper and lead are 
the chief metallic constituents of the cobalt ore. The ores of 
Cobalt, Canada, contain chiefly arsenic, antimony, iron, and copper, 
and in addition, lead and bismuth. 

The world's consumption of cobalt amounts to approximately 
400 tons. The chief source of supply is Cobalt, Canada, but a 
small quantity (80 to 150 tons)* has been obtained within the last 
two years from Queensland, West Australia. The shipments 
from Australia have been made in the form of a concentrate con- 
taining from 20 to 33 per cent cobalt. The consumption is dis- 
tributed between cobalt metal, oxide, and salts in about the fol- 
lowing proportion : metal 175, oxide 200, salts 25 tons. 

The tons of cobalt ore mined in the United States are not 
given separately, but the production of cobalt oxide has been 
recorded. Between 1870 and 1902, the quantity of cobalt oxide 
produced in the United States varied from 5,000 to 10,000 lb. per 
annum. In 1903 and 1908, the production increased to 120,000 
and 100,000 lb. respectively. No further production has been 
reported until 1920 when 102,000 lb. was produced. These large 
recoveries were due to the operation of the ^lissouri mines and 
smelter. 

The ores of Ontario continue to supply practically the world's 

♦Mining Magazine, 26, 97 (1922). 



COBALT — ITS PRODUCTION AND USES. 



343 



requirements of cobalt. A few years ago, it was thought that the 
deposits of Belgian Congo would produce sufficient cobalt to 
satisfy the demands of Europe and Asia, but so far little, if any, 
has been recovered, and it is doubtful whether the recovery of 
cobalt from the copper ores would prove a commercial operation. 
Several reports concerning the deposits of West Australia have 
appeared in the technical journals. In 1922 a crushing and con- 
centrating plant at a cost of $200,000 was constructed. To con- 
centrate at a profit an ore for the cobalt content alone presents a 

Table I. 
Tons of Cobalt Ore Mined. 



Year Ge 


rmany 


Austria 


1 
Norway 


Sweden 


CaSnia ^P*'" 


Canada 


1856 


6 


136 


1 
... 




.... I 






1861 


1 




. . . 




1 






1871 : 


18 




25 






4 




1881 1 


33 


■46 


80 


556 




02 




1891 


176 




187 


244 




60 




1901 


36 




... 




3J23 






1904 


41 












8.964 




"I6* 


1909 














979 




1,533 


1911 


















852 


1916 


















400 


1917 


















337 


1918 


















380 


1919 


















298 


1920 


















283 


1921 


















127 


1922 




... 










.... j 




221 


* Figures fc 


)r Cana 


dian produc 


tion 


a 


re gn 


ren in tons 


of cobalt meta 


. 





For complete Table see report of Ontario Bureau of Mines XXVII, Part 3, 1918. 

difficult problem. It is true the ores of Cobalt, Canada, are con- 
centrated, but the silver recovered is charged with the costs of 
operation. Unless the costs of mining, milling and refining the 
ores of West Australia are low, there will no doubt, be many 
difficulties to overcome before the deposits are fully developed. 



METALLURGY. 

The common methods employed to treat cobalt ores are either 
chemical or smelting. The chemical method is employed more 
for the fairly pure ores, and consists generally in dissolving the 



344 C. W. DRURY. 

metallic constituents of the ore in acid, followed by precipitations 
to remove the various metals and impurities. The smelting process 
which is used almost entirely on the ores of Cobalt, Canada, pro- 
duces first a speiss. The speiss contains approximately 35 to 
40 per cent cobalt and nickel, 15 per cent iron, 35 per cent arsenic, 
and 1100 oz. of silver per ton, in addition to lead and copper. 

The separation of the several metals in speiss from the cobalt 
presents numerous difficulties. These are due mainly to the 
similar properties of the three metals, iron, nickel, and cobalt. It 
is impossible in a commercial operation to separate the previously 
mentioned metals by fire methods, by depending on the different 
degrees of oxidation or reduction. Therefore, in the standard 
process for treating speiss, all the constituents are dissolved in 
acid, sulfuric being commonly employed. The necessity' of add- 
ing acid to dissolve all other metals in addition to the cobalt adds 
greatly to the cost. The similarity of the properties of the three 
metals still exists after being rendered soluble. Alkaline hydrates 
or carbonates, the cheapest precipitants, precipitate under ordi- 
nary conditions hydrates or carbonates of the three metals. The 
large quantities of iron, arsenic, and acid which must be removed 
retain considerable quantities of cobalt solutions, and are a 
source of heavy losses. For the foregoing reasons, it is necessary 
to operate on dilute solutions to effect anything approaching effi- 
ciency in the various precipitations. 

The following figures show the extent of the removal of the 
impurities in the metallurgy' of cobalt. 



analysis 


Co 


Xi 


Fe 


As 


s 


Cu 


SiOz 


Ore 


5 


4 


10 


14 


7 


1 


20 


Oxide 


70.5 


1.0 


0.25 


trace 


0.1 


0.03 


0.2 



The corrosive effect of solutions obtained at the different stages 
in the metallurg}- of cobalt is serious. The handling of large 
tonnages containing sulfuric acid, copper and ferric sulfates 
presents a problem most difficult to solve. Practically every metal 
or alloy on the market has been tested in the solutions, but so 
far nothing has been found which will withstand the corrosion 
and abrasion. It may be of interest to the members of this 
Society to know in the production of 1 lb. of cobalt it is neces- 
sarv to handle 3000 lb. of solution. 



COBALT — ITS PRODUCTION AND USES. 345 

After the sulfur, iron, arsenic and copper have been removed, 
the separation of the cobalt from nickel is the next operation. 
The cobalt is precipitated as cobaltic hydrate Co (OH).; by hypo- 
chlorite solutions. To get a pure product the oxide is dissolved 
and reprecipitated. In the precipitation of cobalt, chlorine is 
evolved, which is hard on the workmen, and the moist chlorine 
gas is very corrosive on exhaust fans and pipe lines. 

The metallurgy of cobalt presents some interesting problems, 
to those engaged in the study of finding a suitable material to 
resist the combined corrosive effect of acid solutions of copper 
and ferric sulfates. 

Recently a patent^ was granted covering the treatment of cobalt 
ores with chlorine gas. It is planned to operate the process at 
the plant of the Coniagas Reduction Co., Thorold, Ont. Little is 
known at present of the details of the process, but it is under- 
stood that the arsenic and iron are volatilized as chlorides at 
certain temperatures. 

USES. 

Cobalt metal is used chiefly in the manufacture of stellite, and 
as one of the main constituents of permanent magnets. The 
superiority of stellite as a cutting tool has been definitely estab- 
lished. The addition of cobalt permits magnets® to be made of 
less than half the weight of those made of ordinary tungsten 
magnet steel. 

The oxide is used mainly for coloring in the ceramic and enamel 
industries and in the preparation of cobalt salts. Cobalt salts are 
used as driers in paints and varnishes, as catalytic agents in the 
hydrogenation of oils, in the preparation of certain printing inks, 
and in stains in the ceramic industries. Cobalt silicate possesses 
a rich blue color and is used extensively in the china trade. In 
enamels, cobalt is used to neutralize the yellow tinge due to iron 
oxide. 

The salts of cobalt which are at our disposal in commercial 
quantities are all of the cobaltous or divalent type. It has been 
found that although they can be readily used in the manufacture 
of driers, and worked like the various compounds of manganese, 

' E. W. Westcott, U. S. Patent No. 1,406,595. 

"Honda and Saite, K. S. Magnet Steel. Electrician, 85. 705. (1920); Steels for 
Permanent Magnets, Electrician, 86, 327, (1921); Kayser, Electrician, 88, 421 (1922). 



346 



C. W. DRURY. 



lead, zinc, calcium, aluminum, etc., the organic compounds 
formed, which are the basis of the so-called driers, are not effi- 
cient while in the cobaltous state. The formation of trivalent 
cobalt compounds is sought in the making of driers. The value 
of cobalt compounds depends not on their power to dry linseed 
oil, but on their ability to make the lower priced semi-drying 
oils act like linseed oil. 

Table II. 
Composition of Commercial Cobalt Compounds. 



Cobalt 

Cobaltous Oxide 

Cobaltous Cobaltic Oxide.. 

Cobaltic Oxide 

Cobalt Acetate 

Cobalt Borate 

Cobalt Carbonate 

Cobalt Chloride 

Cobalt Hydrate: 

Black 

Pink 

Cobalt Nitrate 

Cobalt Linoleate : 

Solid 

Liquid 

Cobalt Phosphate 

Cobalt Resinate 

Cobalt Sulfate 

Cobalt Ammonium Sulfate. 

Cobalt Tungate stereoiso- 
mer of linoleate 



Formula 



Co 

CoO 

C0.O4 

C02O3 

Co(C.H302),.4H.O 
2CoO . 2B2O3 . 4H.0 

C0CO3 

C0CU.6H.O 



Theoretical 
Per Cent 

Cobalt 



Per Cent 
Cobalt in 
Com- 
mercial 
Product 



Co(OH)3 

Co(OH)= 

Co(N03)2.6H.O 



78.65 
73.43 
71.00 
23.70 
32.60 
49.58 
24.80 

53.64 
63.44 
20.27 



Co(Ci8H3i02)2 1 9.56 



Co3(PO.)s.2H.O 

Co(C«H,=O02 

CoSO*.7H.O 

CoSO..(NH02SO..6H2O 



43.92 

4.31 

20.90 

14.93 

9.56 



I 97.5 
75.0 
70.5 

23.6 

30.0 
43.5 
24.0 

S0.+ 
57-62 
20 

7.-7.5 

5.0 

41.0 

1.5 (fused) 

20-21 
14.5 



In conclusion it may be added that unless some extensive cobalt 
deposits are found, the source of cobalt is limited. The cobalt 
content of the present ores is gradually decreasing and the 
impurities are increasing, which has a tendency to raise the cost 
of production. The superiority of cobalt and its compounds in 
the stellite, magnet steel, ceramic, paint and varnish industries 
has been established. The properties of cobalt and its com- 
pounds are remarkable, varying from imparting great hardness 



COBALT — ITS PRODUCTION AND USES. 347 

and strength in stellite, high magnetic retentivity in permanent 
magnets, beautiful blue color in china and enamels, to its action 
as a catalytic agent in the oxidation or hydrogenation of oils. The 
demand for cobalt or its compounds is becoming greater, but its 
use will no doubt, be confined to those industries in which the 
price of the raw material is small in comparison with the results 
achieved or savings effected. 



DISCUSSION. 



Kenneth S. Guiterman^ (Communicated) : I have read this 
paper with exceeding interest. Having in mind the fact that the 
cobalt industry as such would undoubtedly be materially benefited 
through a better understanding of the metallurgy, I venture to 
emphasize some of the salient features which have apparently 
escaped the attention of Prof. Drury. 

As is undoubtedly well appreciated, the primary cause of the 
high cost of producing cobalt has, in the past, been a consequence 
of the cumbersome and highly unsatisfactory method of separat- 
ing it from its constituent, nickel. This has almost universally 
been accomplished through the medium of sodium or calcium 
hypochlorite. Through the addition of this oxidizing agent to an 
essentially neutral solution containing both cobalt and nickel, it 
was possible to precipitate a hydrated oxide of cobalt. Unfor- 
tunately, the precipitation was extremely imperfect, in that the 
precipitant likewise reacted with nickel. The net result of this 
was that the separation had to be carried out through numerous 
fractionizations, each product thereof containing varying propor- 
tions of cobalt and nickel. Hence, it is obvious that an operating 
plant became burdened with large quantities of intermediary by- 
products, none of which were suitable for the market and all of 
which necessitated re-treatment. 

In 1914 and 1915 the Research Department of the American 
Smelting and Refining Company, under my direction, undertook 
the development of a new and more efficient process for the sep- 
aration of cobalt and nickel. This work was largely a conse- 

iNew York City. 



348 DISCUSSION. 

quence of the Smelting Company having in its possession large 
tonnages of cobalt-nickel speiss. This speiss, of course, locked up 
an appreciable amount of both gold and silver. Hence, it was 
primarily with a view to recovering these precious metals that 
the process was devised. 

After some months of laborious and pains-taking work, a 
method of electrochemical separation was devised, whereby it 
became possible to separate cobalt from nickel electrolytically and 
without the formation of by-products, under conditions of operat- 
ing efficiency in excess of 98 per cent. The process, as patented 
by myself, consisted briefly of sulfating the speiss, followed by 
a solution thereof in water. After the preliminary removal of 
iron, arsenic, copper, etc., the resultant cobalt-nickel sulfate solu- 
tion was evaporated to a high degree of concentration. Salt was 
added slightly in excess of the theoretical quantity necessary to 
produce nascent sodium hypochlorite. The solution was then 
electrolyzed in soapstone hopper-bottom tanks, under conditions 
of great velocity of circulation and high current density. Copper 
cathodes and graphite anodes were employed. The solution was 
maintained faintly acid at all times through the addition of a 
solution of sodium carbonate of approximately N /\ normal. In 
order to preclude the formation of insoluble carbonates, the addi- 
tion of the sodium carbonate was made in the form of a cloud 
over the reservoir containing the circulating sulfate solution. 
Regulation of the acidity was maintained throughout the entire 
process by frequent electrotitrometric determinations, litmus and 
other indicators being worthless, because of the intense green 
color of the solution. 

The current efficiency of the process was excellent, and as I 
have stated above, the separation of the cobalt from nickel was 
all that could be desired. The end-point of the reaction was mani- 
fest through the practical absence of cobalt in solution. As soon 
as this moment was reached, the entire solution was filter-pressed, 
thereby removing the hydrated oxide of cobalt from suspension. 
This was washed in the usual method with water and possibly 
dilute sulfuric acid. The filter-pressed cakes after discharge 
were then calcined, so as to produce the gray or black oxide of 
cobalt as might be desired. 



COBALT — ITS PRODUCTION AND USES. 349 

Throughout the entire operation of the plant, the process func- 
tioned without difficulty, and the most high-grade product was 
put on the market. Insofar as costs were concerned, I may say 
that they were low, and would have permitted of the active com- 
petition of cobalt versus nickel, without appreciable danger to 
the former. 

The above briefly described method is, in my judgment, emi- 
nently superior to the others which have so far been devised, 
including that of treatment with chlorine gas. The objection to 
all of these is that by-products either form or are so liable to 
formation as to render the process hazardous. No such condition 
presents itself in the electrolytic method. 

E. O. Benjamin- : A use was devised for cobalt by I. H. 
Levin, as an oxygen electrode in electrolytic cells, claiming a 
higher efficiency or lowering of the oxygen over-voltage. But 
since the time of the appearance of that patent", as well as the 
description, I have made some experiments which do not seem 
to confirm that claim. I have found the efficiency of a cobalt 
electrode is somewhat lower than that of a nickel electrode. 

Colin G. Fink* : May I ask Mr. Benjamin if a cobalt-plated 
iron electrode was used? 

E. O. Benjamin : Yes. 

Colin G. Fink : Our tests have shown that a cobalt-plated iron 
electrode is decidedly Better as an oxygen electrode than a nickel- 
plated iron electrode. Perhaps you did not get enough cobalt on 
your electrode. 

O. C. Ralston-"' : I am a little surprised to hear the present 
commercial methods of separating nickel and cobalt accused of 
being so inefficient. It recalls a little piece of work done by M. J. 
Udy and myself some years ago on separating these two metals 
from each other. Chlorine was used to oxidize the cobalt to the 
higher stage of oxidation in the presence of finely divided calcium 
carbonate to cause its hydrolysis to the black oxide. As long as 
the solution was kept cold only the cobalt precipitated and the 

- Consulting Engr. and Chemist, Newark, N. J. 

3U. S. Pat. 1,214,934. 

< Consulting Metallurgist, New York City. 

' U. S. Bureau of Mines. Berkeley, Calif. 



350 DISCUSSION. 

separation was practically quantitative. In fact, Mr. Udy, who 
did most of the experimental work, told me that he found he 
could use it also as an analytical method and that it seemed to 
be more sensitive than the dimethyl glyoxime separation. 

Colin G. Fink : I may add to Mr. Ralston's remark that Prof. 
Edgar F. Smith and Prof. H. S. Lukens, of the University of 
Pennsylvania, have worked out an analytical method for the 
separation of cobalt from nickel^ Cobalt is deposited as an oxide 
at the anode, and nickel as metal at the cathode. 

R. B. Moore" : The price of cobalt oxide for a good many 
years was from $1.00 to about $1.50 a pound, and then it went 
up to $4.50. We tried to investigate why that was, but without 
success, unless it was that at that time the principal cobalt prop- 
erty in this country was absorbed by foreign interests. However, 
the question that is obvious is, how long would a $3.00 price last 
if other companies got into the game? There are a number of 
small cobalt deposits in this country, and naturally if there were 
a chance of their succeeding we would like to see them do some- 
thing. But under such conditions, would the price of $3.00 a 
pound suddenly drop? 

C. W. Drury (Communicated) : Mr. K. S. Guiterman empha- 
sizes the electrochemical method of precipitating cobalt compared 
with that employing hypochlorite solutions. In the electrochemi- 
cal method, it appears that the salt is electrolyzed, giving chlorine 
and caustic. These two products unite in the cell, giving what 
Mr. Guiterman calls "nascent hypochlorite." 

To produce cobalt as cobaltic hydrate, a certain quantity of 
hypochlorite is necessary. The standard, as well as the Guiter- 
man method, requires hypochlorite, and the whole question under 
discussion appears to be whether hypochlorite can be prepared more 
cheaply from calcium bleach, liquid chlorine and soda, or by elec- 
trolyzing the salt solution as in the Guiterman method. Special 
attention has been given to the development of cells to produce 
chlorine efficiently, e. g., Nelson, Allen :Moore, and Townsend, 
and even in the best an energy efficiency of 60 per cent is high. 

•Trans. Ain. Electrochem. Soc, 27, 31 (1915). 
7 do The Dorr Co., New York City. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City. May 4, 1923, President Schlueder- 
berg in the Chair. 



CHROMIZINC' 

By F. C. Kelley.' 

Abstract. 

It is the purpose of this paper to give a brief summary of 
the work which has been done to date upon the diffusion of 
metals in the soHd state, and to describe in detail the process 
of chromizing, and its effects upon the physical and chemical 
properties of iron. The practical application of this process 
is also considered. 

There are many other metals which diffuse in the same manner 
when brought into contact with each other at temperatures below 
their melting points. This field may be the subject of a future 
paper. 



SUMMARY OF LITERATURE. 

It has long been known that solid bodies are capable of diffus- 
ing into one another. The old cementation processes are based 
upon this fact, but it is only within comparatively recent years 
that any practical use has been made of this knowledge. 

Faraday and Stodard in 1820 while experimenting on the 
alloys of iron observed that steel and platinum wires when tied 
together in bundles could be welded at a temperature considerably 
below that at which either of the metals melted. Upon etching 
the welded mass with acid, the iron appeared to be alloyed with 
the platinum. 

Chemoff in 1877 discovered that if two surfaces of iron are 

' Manuscript received February 1, 1923. 

» Research Laboratory. General Electric Co., Schenectady, N. Y. 

3M 



352 F. C. KELLEY. 

heated to 650° C. in intimate contact with each other they will 
unite. 

Spring in 1882 discovered that alloys might be produced by 
compression of their constituent metals in a fine state of division. 

Hallock in 1888 showed that similar results to those of Spring 
could be obtained at higher temperatures without pressure. 

Roberts-Austen in 1896 published results of experiments on 
diffusion of gold in solid lead at various temperatures, and in 
1900 published additional data on the same work in the Pro- 
ceedings of The Royal Society. 

C. E. Van Ostrand and F. P. Dewey of the U. S. Geological 
Survey in 1915 checked up Roberts-Austen's work. 

Tycho Van Aller of the General Electric Company patented in 
1911 a process (calorizing), which depends upon the diffusion 
of aluminum into metals below its melting point. 

E. G. Gilson, of the General Electric Company, patented in 
1914 another process of calorizing metals, in which greater pene- 
tration of aluminum is obtained by operating at higher tempera- 
tures, and in an atmosphere which protects the aluminum from 
oxidation. Hydrogen is the usual atmosphere used. 

Cowper-Coles, in June, 1902, and in August, 1906, received 
patents on coating iron with zinc to protect it from corrosion. 
The zinc forms an alloy with the iron at a temperature below 
the melting point of zinc, and the surface of the coated metal 
is nearly pure zinc, which resists corrosion. 

Collins and Capp, of the General Electric Company, patented 
a process of sherardizing in January, 1916, in which they de- 
scribe an improved sherardizing process, in which the zinc con- 
tent of the sherardizing mixture and the temperature are 
correlated in a new way. 

Calorizing and sherardizing are two commercial processes 
which depend upon the alloying of metals at temperatures below 
their melting points. In the case of calorizing I refer to the 
Van Aller process. 

Chromizing, the subject with which this paper is chiefly con- 
cerned, is another patented process which depends upon this 
same property of diffusion of metals at temperatures below their 
melting points. 



CHROMIZING. 353 

THE METHOD. 

The process consists of packing the material to be treated into 
a powdered mixture of ahimina and chromium. The amount of 
each material used in the mixture is 45 per cent of alumina and 
55 per cent of chromium by weight. The material is usually 
packed into a tube of iron, and then heated at 1300 to 1400° C. 
in hydrogen, in vacuum or in some neutral atmosphere, for 
lengths of time depending upon the penetration and concentration 
of chromium desired. 

Where a protective atmosphere like hydrogen is used it is 
absolutely necessary that it should be free from all oxygen and 
water vapor, for at the high temperatures at which this work 
is carried on the chromium powder would be rapidly consumed 
by oxidation. In fact as soon as a film of oxide is formed on 
the surface of the fine particles they refuse to react with the 
metal to be chromized. This purification is accomplished by 
first passing the hydrogen through a sulfuric acid tower, to 
remove most of the water. The gas is then passed over a copper 
gauze, heated to about 600° C, to get rid of any oxygen present 
by combining the oxygen with the hydrogen, the copper acting 
as a catalyzer. The water formed in the copper furnace is then 
taken out by passing the gas through additional sulfuric acid 
towers, after which it is passed over potassium hydroxide to 
take out any sulfuric acid vapors. Finally it is passed over 
phosphorus pentoxide to remove the last traces of moisture. 
This gas then goes directly to the chromizing furnace. 

The furnaces used for this work consist of alundum tubes 
wound with molybdenum wire as a heating unit. These tubes are 
placed in a suitable furnace casing and surrounded with alumina 
powder, which acts as a heat insulating material. 

The hydrogen atmosphere of this furnace serves a double 
purpose. It not only prevents the burning up of the chromium, 
but it also protects the molybdenum from oxidation, and thus 
enables us to attain with ease the high temperatures at which 
we operate. 

In order to indicate the size of the furnace of this type which 
may be used to advantage, I may say that we have operated two 
furnaces, which were each made of four alundum tubes, 60 cm. 



354 F- C. KELLEY. 

long, 20 cm. inside diameter and 13 mm. walls, placed end to 
end in a metal casing, and held in line by means of a strip of 
sheet molybdenum 25 mm. wide and 0.63 mm. thick bound 
around the tubes at the joints. The tubes at the joints were 
supported in the furnace casing by fire brick cut to fit the tubes. 
The molybdenum band also serves to keep the alumina from 
falling into the furnace through the joints formed at the ends 
of the tubes. 

The winding for these tubes was molybdenum wire 1.91 mm. 
diameter, and there were two windings on each tube. Each 
winding consisted of 22 turns 12.7 mm. apart, with the exception 
of the two end windings, which were wound 8.5 mm. apart to 
compensate for radiation at the ends of the furnace. The furnace 
casing was 2.74 meters long and 53.3 cm. square. The inside was 
lined with a single row of fire brick, and the space between the 
brick and furnace tube was filled with alumina. 

The furnace was operated directly from a 1000-volt a. c. 
generator, by means of a resistance in the field of the machine. 
Two large transformers, connected in parallel, were used to 
step the voltage down from 1000 to as low as 12 volts. The 
windings of the furnace were all connected in parallel. 

These furnaces will carry without trouble a charge weighing 
136 kg. (300 lb.) distributed over 1.83 m. (6 ft.) of its length 
at 1350° C. 

The chief use for these furnaces was in chromizing turbine 
buckets, which have been installed in various turbines through- 
out the country, in order to test them for corrosion under actual 
operating conditions. 

MATERIALS REQUIRED. 

In chromizing it is necessary to have powdered chromium of 
at least 95 per cent purity, for chromizing iron which is intended 
to withstand corrosion. Powdered AI2O3 is necessary as a di- 
luting agent, and to prevent excess sintering of the powdered 
material at high temperatures. It is also necessary to have pure 
hydrogen, free from moisture and oxygen. And last of all it 
is necessary to have a furnace which will operate at a temperature 
of 1300° C. or higher, and in an atmospliere of hydrogen. 



CHROMIZING. 



355 



STRUCTURE. 
Chromized iron, with which I am going to deal chiefly, when 
examined under the microscope, has a structure which seems 
to be characteristic of all metallic coatings obtained by diffusion. 
This chromium-iron alloy, which is a solid solution of chromium 
in iron, is made up of an area of elongated grains, with their 
longer axes perpendicular to the surface chromized, and the line 





Fig. 1. 
Clironiized iron heated at 1,350° C. for 4 hr. x 70. 



of penetration is generally very sharp. Sometimes there seems 
to be a cylinder of grains arranged in this manner on the surface 
of a chromized iron rod. Then again there seems to be two or 
more such bands or cylinders, which contain varying amounts 
of chromium, for each band etches up differently. The one with 
the highest chromium content etches up the slowest. 

Fig. 1 illustrates the chromized iron surface, consisting of a 
layer of elongated grains. The longer axis of each grain is 



356 



F. C. KELLEY. 



at right angles to the surface chromized. Fig. 2 illustrates a piece 
of chromized iron, showing two distinct bands on the surface. 
If we were to analyze samples from each band, we would find 
that the inner band had a lower chromium content than the 
outer band. 





Fig. 2 
Chromized iron showing banded structure of the chromized section. 

Fig. 3 also shows three distinct bands outside of the iron core. 
The outer band, which is very narrow, seems to be made up of 
almost pure chromium, sintered together and alloyed to the 
chromium-iron band just underneath. This is a cross section of 
a sample fired in pure chromium at 1350° C. for 3 hr. 

If we chromized a sample at the same temperature as the 
sample shown in Fig. 1, but for twice the length of time (8 hr.) 
we would get no sharp line of penetration, and the large elon- 
gated grains we would find had broken into somewhat smaller 
grains, as is shown in Fig. 4. If we analyzed the surface coat- 



CHROMIZING. 



357 



ings of samples shown in Fig. 1 and 4, we would find that the 
sample of Fig. 1 would show the higher per cent of chromium. 
The chromium content of the other sample would be reduced, 
due to greater diffusion for it has been fired twice as long. 







Fig. 3. 
Chromized iron heated in pure chromium powder at 1,350° C. for 3 hr. x 57. 



CONTACT PROCESS. 
In chromizing, even at these high temperatures, the vapor 
pressure of chromium is very low, and all of the chromium which 
is taken up by the iron must be in contact with it. If it is de- 
sired to increase the chromium content of a surface coating, it 
is necessary to give the sample a second treatment. This fact is 
illustrated by examination of the somewhat sintered chromizing 
mixture where it has been in contact with the iron treated. The 
surface of the sintered mixture is white, showing that all of the 
chromium has been taken up by the iron surface in contact with 



358 



F. C. KELLEY. 



these finely divided particles, leaving only the white AI2O3 behind. 
If this sintered piece of mixture is broken at right angles to the 
surface examined, chromium particles will be found just under 
the AI2O3 surface. 




Fig. 4 
Chromized iron heated at 1,350° C. for 8 hr. x 42. 



THE EFFECT OF CARBON. 

In order to get the best chromizing results it is necessary to 
use an iron or steel of low carbon content, for iron of high 
carbon content does not chromize well. The carbon seems to 
retard the penetration of the chromium. It is possible to chro- 
mize it if it is first decarbonized by firing in hydrogen. Another 
essential point is to have the samples to be chromized well cleaned 
and free from oxide or rust. 



CHROMIZING. 359 

THE DIFFICULTIES. 

The AUOo if new should first be fired before using, in order 
to drive out any moisture which it may have taken up. Then 
it may be mixed with chromium powder and kept in closed 
cans. This mixture may be used over and over again, and 
chromium added at intervals to maintain the chromium content. 

The determination of the amount of free chromium metal 
present is one of the worst troubles with which we had to con- 
tend. We were not able to determine the amount of chromium 
present exclusive of the oxides of chromium. The only way 
that we could check up our mixture was to put test samples in 
each run and compare these samples with others which we 
considered good. 

It is almost impossible to run a furnace of the type which 
I have described without getting some oxidation, because the 
AI2O3 used as the furnace insulation and also as a part of 
the chromizing mixture is active towards moisture. But where 
the furnace and mixture are being constantly used, there is little 
chance to take up moisture, and under these conditions we get 
the best results. The oxidation of the chromium mixture always 
took place to some extent at the open end of the containing 
vessel, and this powder at the end was always discarded, so as 
not to contaminate the rest of the mixture when used again. 

CHROMIZING DATA. 

In order to give an idea of the amount of chromium taken up 
by a sample and the penetration I shall give the data shown in 
Table I. These samples were about 1.27 cm. x 1.27 cm. x 1.27 
to 1.59 cm. (H X ^ x ^ to ^ in.) Three samples were used 
and one sample was taken out after each chromizing run at 
1300° C. for 3 hr. 

Table II contains the data on samples heated at 1200° C, 
1350° C. and 1400° C. for 3 hr. periods. 

Fig. 5 shows the effect of time upon the penetration of chro- 
mium at 1300° C. The samples were rechromized into a new 
mixture after each run of 3 hr. 

Fig. 6 shows the effect of temperature upon the penetration, 
where the time of heating at each temperature is maintained 
constant for 3 hr. 



36o 



F. C. KELLEY. 



We must remember that in firing a sample of iron in a chro- 
mizing mixture and in a hydrogen furnace, that a sample which 
is fired at 1400° C. must be brought up through the range of tem- 
peratures between 1200-1400° C, and that chromizing and dififu- 

Table I. 
Chromizing Data. 



Sample ' Weight before 
jtq chromizing 


Weight after 
first chromizing 


Difference in 

weight in 

grams and 

per cent 


Weight after 

second 
chromizing g. 


2.1 19.7518 

2.2 ' 21.9863 

2.3 23.1170 

1 


19.8861 
22.1382 
23.2802 


0.67 per cent 
0.1343 g. 
0.69 per cent 
0.1519 g. 
0.706 per cent 
0.1632 g. 


22.2325 
23.3780 




Difference 

in weight in 

per cent and grams. 


Weight after 3rd 
chromizing g. 


Difference in ^--f^^^ P|- 
^^af^p^r f.T <=^-r" 


2 1 








0.178 

0.343 
0.558 


22 


1.12 per cent 
0.2462 g. 

1.13 per cent 
0.2610 g. 






2.3 


23.3275 1.77 per cent 
0.4105 g. 



Table II. 



Sample 
No. 



Weight 

before 

chromizing 

g- 



H.1.12 


16.5594 


H.1.135 


20.7165 


H.1.14 


21.9600 



Weight Difference in ' Tempera- 
after weight in per cent ture in 
chromizing a^d grams °C. 
g- 



16.5776 
20.8590 
22.220 



0.11 per cent 
0.0182 g. 
0.69 per cent 
0.1425 g. 
1.18 per cent 
0.2600 g. 



Average 
Penetra- 
tion 
mm. 




sion are taking place during the time that the sample is being 
heated through this range. It is almost impossible to put a chro- 
mizing charge into a hydrogen furnace at 1200-1400° C. without 
having the entire charge blown out of the containing tube due to 
the sudden expansion of gases. Even if this were possible it 



CHROMIZING. 



361 



would be hard to judge just when the samples within this heat 
insulating mixture came up to any given temperature. These 
figures then must be taken as the average obtained in standard 
practice. 

It is almost impossible to chromize a steel of high carbon con- 
tent, such as drill rod, until after the carbon content has been 
greatly reduced by decarbonization, as by firing in hydrogen. If 




1^5 




















1 


LOO 


(0 




















ys 


5 










^ 

^ 










.50 


1 














( 






.25 


^ 
^ 












^ 








( 
n 




TFMP 


FfffJU 


/rfT. 



Curve showing the change in penetra- 
tion of chromium with the time. 



/200 1500 f^OO 

Fig. 6. 

Curve showing the effect of temperature 

u|)on the penetration of chromium. 



a sample of drill rod is chromized at 1300^ C. in the regular way, 
we notice that it has lost in weight, but, upon examination, we 
find that some chromium has been taken up by the iron. When 
we polish a cross section of the sample, and examine it under the 
microscope, we find that the penetration is very irregular and 
varies so much that it is not possible to state even the average 
penetration for such a sample. There seem to be shiny needle- 

24 



362 



F. C. KELLEY. 



like projections from the well-defined chromized ring at the edge, 
which is about 0.05 to 0.076 mm. (0.002-0.003 in.) in width. 
Upon refining a sample a second and still a third time, we notice 
that the sample begins to increase in weight, because the carbon 
is nearly all taken out of the sample by the hydrogen. The chro- 
mized ring takes on a much more regular shape or has a more 
uniform penetration, and with each firing takes up an increasing 
amount of chromium. 

The data given in Table III are obtained by firing three drill 
rod samples of about 0.8 per cent carbon in chromizing mixture 
at 1300° C. for 3-hr. periods, removing one sample after each 
firing. 

Table III. 
Chromizing Drill Rods 



Sample 
No. 


Weight before 

chromizing 

g- 


Weight after 

first chromizing 
g. 


Difference in 

weight in g. and 

per cent 


Weight after 

second 

chromizing 

g. 


3.1 

3.2 
3.3 


19.6248 

20.6339 
19.7910 


19.6152 
20.6256 
19.7890 


0.05 per cent 
—0.01 g. 

0.04 per cent 
—0.008 g. 

0.01 per cent 
—0.002 g. 


Removed 
20.6958 
19.8630 




Difference in weight 
in g. and 
per cent 


Weight after 

third chromizing 

g- 


Difference in 

weight in grams 

and per cent 


Average pene- 
tration of Cr 
mm. 


,, 








076 


3.2 


0.34 per cent 
+0.07 g. 

0.37 per cent 
+0.074 g. 


Removed 
19.9783 




127 


3.3 


0.957 per cent 
+0.1893 g. 


0.420 



In order to show the effect of diffusion at 1350° C, I took 
eight especially turned sample rods and chromized them all at 
1350° C. for 3 hr. I took out sample No. 1 and had the chro- 
mized surface turned off to the depth of penetration of the 
chromium. The remaining seven samples were then fired in 
hydrogen for an equal length of time at 1350° C. and sample 
No. 2 was taken out and the chromized surface turned oflF. This 
was repeated until we had chromized four times and reheated in 



CHROMIZING. 



)63 



hydrogen four times. The samples were taken out as above, one 
by one in their order. After each treatment the turnings were 
analyzed for chromium content. The results are given in 
Table IV. 

Table IV. 





Time 


Time heated 


Temperature of 


Per cent 


Sample 


chromized 


in Ha 


chromizing and 


of 


No. 


hr. 


hr. 


heating °C. 


chromium 


1 


3 




1350 


10.42 


2 


3 


3 


1350 


6.97 


3 


6 


3 


1350 


12.15 


4 


6 


6 


1350 


8.70 


5 


9 


6 


• 1350 


15.50 


6 


9 


9 


1350 


9.62 


7 


12 


9 


1350 


14.39 


8 


12 


12 


1350 


9.77 



We must remember that this analysis represents the average 
chromium content of the layer turned ofif. The chromium content 
of this layer near the surface of the sample is much higher than 
the average shown by analysis. The fact that the percentage of 
chromium content decreases each time after firing in hydrogen 
is due to increased penetration of the chromium into the chro- 
mized layer. Since the surface is not in contact with chromium 
when reheated in hydrogen, it is not able to take up additional 
chromium. The diffusion of the chromium, gained by chro- 
mizing, through a greater volume of the sample by means of 
firing in hydrogen decreases the percentage of chromium content. 

We notice that with each additional chromizing treatment the 
tendency of the chromized layer is to increase in percentage of 
chromium content above that of the previous chromizing, in spite 
of the fact that between each chromizing the chromium content 
of this layer has been reduced by diffusion. That is, the chro- 
mium content of the layer is reduced on the average by hydrogen 
firing 4.24 per cent, and for every time it is rechromized it 
increases on the average of 5.4 per cent, so the net result is a 
continual percentage increase of the chromium with each 
chromizing. 

Fig. 7 is a photograph about actual size taken of samples which 
have been alternately chromized and heated at 1350° C. The first 



364 



F. C. KELLEY. 



sample shown at the left is chromizecl, and from left to right they 
are alternately chromized and heated so that the last sample has 
been chromized four times and heated four times. The pene- 
tration is quite sharp in each sample with the exception of sample 
No. 2, which has been heated in hydrogen for 3 hr. after the first 
chromizing. The diffusion of the chromium has decreased the 
distinctness of the chromized laver. 




Fig. 7. 

Samples of chromized iron showing the effect of alternate chromizing and 
heating, x 1. 

The effect of concentration of chromium powder is shown when 
we pack the samples to be chromized into pure chromium powder, 
for the penetration at any given temperature for a given length 
of time is greatly increased. This is shown in Table V. 



Table V 









j 






Tem- 




Sample 


Weight before 


Weight 

after 


gain in 


Per 

cent 


Time 
of 


pera- 
ture of 


Pene- 


No. 


chromizing 


chromizing 


weight 


gam 


chro- 


chro- 


tration 




g- 


g- 


g. 


in 


mizing 




mm. 








weight 


hr. 


•c 




1 


43.8459 


45.8186 


1.9727 


4.5 


3 


1350 


0.852 


2 


43.7816 


45.5701 


1.7885 


4.10 


3 


1350 




3 


43.7585 


44.9604 


1.2019 


2.74 


2 


1350 


0.533 


4 


43.8480 


44.8967 


1.0487 


2.40 


2 


1350 


• • • • 


5 


43.7020 


44.7787 


1.0767 


2.46 


1 


1350 


0.406 


6 


43.7895 


44.7177 


0.9282 


2.12 


1 


1350 






The percentage gain in weight is much greater where pure 
chromium is used, for the pure chromium particles are fused to 
the surface in a much closer arrangement, and the rate of diffu- 
sion being so nuich greater also helps to account for the increase 
in weight. 



CHROMIZING. 



365 



In order to get some of the physical characteristics of chro- 
mized iron, I fired some iron wire in vacuum at 1300° to 1400" C. 
for 1.5 hr. and obtained the results recorded in Table VI. 

TabIvE VI. 
Physical Characteristics of Chromized Iron. 



Tem- 
perature 
of chro- 
mizing 
"C. 


Time Weight 
chro- before 
mized chromizing 
hr. g. 

1 


Weight 
after 
chromizing 
g- 


1 

Per cent [ Diameter 
increase before 

in chromizing 
weight mm. 


Diame- 
ter after 
chro- 
mizing 
mm. 


\m\~ 1.5 ' 2.2673 

1400 2 2.2666 

i J 


2.568 
2.7705 


11.7 0.89 
22.6 


1.0 




Per cent 

increase 

in diameter 


Resistance 
before chro- 
mizing in mi- 
crohms per 
cc. 


Resistance 
after chro- 
mizing in 
michrohms 
per cc. 


Specific 

gravity before 

chromizing 


Specific 

gravity after 

chromizing 


1300- \ 
1400 ( 
1400 


12.9 


11.53 


86.2 


8.11 


7.62 



This wire had a large grain structure, but was not brittle. It 
was surprisingly soft for the amount of chromium which it had 
taken up. The chromium had diffused entirely through the wire. 
It was heated in the open air by passing a current through it at 
1050° C. for 200 hr. without burning out, thus showing the pro- 
tective value of chromium as far as oxidation is concerned. 



RESISTANCE TO CORROSION. 

In testing samples of chromized iron, we ran them in salt spray 
along Avith blanks and found that after a month the blank sample, 
3 mm. (0.125 in.) thick, was about half corroded away, while a 
chromized sample had here and there slight signs of attack. 

Chromized samples tested along with sherardized iron samples 
in salt spray after six weeks showed only slight attack and held 
up under test just as well as the sherardized samples. 

The samples under test showed up so well that we made addi- 
tional tests upon turbine buckets. These chromized nickel steel 
buckets showed up so well that the Turbine Department decided 



366 



F. C. KELLEY. 




Fig. 8. 

Chromized and uncliroinized nickel steel turbine buckets 
after one year of actual service. 



CHROMIZING. 367 

to put them into various turbines throughout the country, and 
into some of the turbines of ocean-going vessels. The best com- 
parison of resistance to corrosion of chromized and unchromized 
turbine buckets under service conditions is illustrated in Fig. 8 
of this paper. These buckets were run side by side in the same 
wheel of a turbine for one year. The unchromized nickel steel 
bucket at the left has its edge entirely corroded and eroded away, 
and in addition the face of the bucket is badly corroded. The 
chromized bucket on the right is in perfect condition, showing no 
signs of corrosion. 

EFFECT OF HEAT TREATMENT. 
In cases where the material chromized must stand high tension 
and fatigue stresses, the high temperature of chromizing lowers 
the resistance of the material to these stresses, but by proper heat 
treatment the original properties may be almost completely 
restored. 

EFFECT OF CARBONIZING. 

Carbonizing of chromized iron lowers its resistance to corro- 
sion, and polished samples of chromized iron which have been 
case hardened will show numerous globules of water if allowed 
to stand in the open air for only a short time. 

Chromized iron itself is quite soft and ductile, but by case 
hardening and heat treatment it may be made very hard. 

RESISTANCE TO ACIDS, 

Chromized iron samples were tested in 10 per cent HCl, HNO3 
and H2SO4. They stood up for five months in the 10 per cent 
HNO3 without discoloring the solution or showing any signs of 
attack, but they broke down almost immediately in the other two 
acids. 

ADDITIONAI, PROPERTIES. 

In addition to these characteristics, chromized iron has a silver 
color, it takes a high polish, and the most remarkable thing about 
it is its softness even where large percentages of chromium are 
present, 

OTHER CHROMIZED METALS. 

There are other metals which may be chromized besides iron, 
but under somewhat different temperature conditions. Nickel 



368 DISCUSSION. 

may be chromized if the temperature used does not exceed 
1300° C. If a higher temperature is used the eutectic alloy of 
(Cr-Ni) is formed and the whole mass melts. The composition 
of this alloy is (42 per cent Ni, 58 per cent Cr) and it melts just 
under 1300° C. There does not seem to be much trouble with 
fusion when chromizing at 1300° C, because the rate of diffusion 
of chromium into nickel is slow at this temperature. 

Molybdenum and tungsten may also be chromized, but in order 
to get any penetration a temperature of 1600° C. is necessary, 
which is above the critical point of cr}'stallization, and the wire 
obtained is of large grain structure and very brittle. 

ANOTHER APPLICATION. 

Chromizing may be used for another purpose than protection 
from corrosion. It may be used to prevent the flow of a metal 
like copper on iron at a temperature above the melting point of 
copper. In a case like this it is better to oxidize the chromized 
metal first before attempting to use it. If the chromized metal, 
say iron, is used to prevent copper from wetting it in hydrogen at 
above 1200° C, it will if fired for long enough time eventually 
alloy with the copper, due to the lowering of the concentration of 
chromium at the surface, due to dififusion. But it will resist alloy- 
ing for a limited length of time even at this high temperature. 

This is an interesting field of research, and there are indica- 
tions that there may be future developments and applications for 
metals treated by dififusion processes. 



DISCUSSION. 

CoLTN G. FiNK^ : Mr. Kelley states that hydrogen performs 
two functions. One is to keep the chromium in reduced condi- 
tion, and the other is to prevent the molybdenum resistor from 
oxidizing. Without the hydrogen, the alloying between chromium 
and iron would probably not take place. Hydrogen is the only 
efficient "flux" that I know of commercially for this case. 

L. O. Hart- : I\lr. Kelley's paper opens up a new field. There 
seems to be, from a manufacturing standpoint, some objections to 

' Consulting Metallurgist, New York City. 
* Driver-Harris Co., Harrison, N. J. 



CHROMIZING. 369 

this process. The requirements of temperature and purity of 
hydrogen mean that the process of chromizing necessarily must 
be an expensive one. It requires expert supervision and ex- 
pensive apparatus, and it seems to me that a number of the results 
might be obtained more cheaply by making the articles of a 
chrome-iron alloy rather than chromizing a steel or a nickel steel. 
If the process were capable of operation at a cost comparable 
with sherardizing, I think that chromizing would have a much 
wider application than it has now. 

H. K. Richardson^: We have three things to say about this 
process. At present we are using a process in an experimental 
way, of chromium plating nickel-steel wire. This wire is heated 
in its final stage of preparation to about 1,100° C, and for less 
than half a minute. The process is continuous, whereby a strictly 
adherent coating of ductile chromium is made upon an under- 
coating of nickel steel. 

I would like to speak about one or two of our observations. 
Mr. Kelley's curve on page 361, regarding the penetration in time, 
does not seem to be borne out in its lower regions by our experi- 
ence. We have a penetration of about 0.01 mm. in a half minute 
or less. 

Regarding the amount of chromium, we put 8 per cent or 
thereabouts upon a wire, and that coating after passing through 
the process at 1,100° C. can be drawn, under the right conditions, 
from 25 mils to 10 mils, with little cracking on the surface. 

Now some friends have taken this coating and have submitted 
it to X-ray analysis. The resulting spectrogram shows that the 
chromium has inter-penetrated the nickel-steel lattice and as such 
has made a much more dense alloy than Mr. Kelley shows here. 
There is no indication at 250 magnifications of any crystals what- 
soever on the coating. Sometimes the coating can not be seen 
at 250 magnifications. The only way that we can find out that 
we have a coating is by special etches. That is, when things have 
been done rightly. We do not always get the result, for some- 
times, due to faulty cleaning, we have a line of demarcation 
between the chromium coating and the nickel-steel under-body. 

In our own work we can not use any nickel-iron-chromium 
alloy, because it would have too high a resistance, and it would 

' Westingliouse Lamp Co., Bloomfield, New Jersey. 

25 



370 DISCUSSION. 

have a wrong coefficient of expansion. So we are limited to an 
under-body which has the right coefficient of expansion. The 
chromium serves only the purpose of making the contact between 
the glass and the right coefficient under-body. 

F. C. KelIvEy : In answer to Dr. Fink's statement, that hydrogen 
is acting as a flux in this process, and is the essential thing which 
makes it work, you may call hydrogen a flux, or whatever you 
will. It is not essential to the operation of the process, but it is 
the most convenient way of preventing oxidation and of carrying 
on the process. It can be done in a lamp exhausted down to very 
low pressures. I will go so far as to say that from my experience 
and knowledge of the facts, an iron wire can be chromized inside 
of a lamp where the pressure is extremely low, as low as the best 
vacuum we know, 

I have treated cold-rolled iron in this same way and at these 
same temperatures in vacuum, and produced the same results. 
I should say that good, clean contact surfaces between the pow- 
dered chromium and iron, and an atmosphere where oxidation 
can not take place, or a vacvmm, are the essential conditions under 
which this temperature treatment should take place. 

In regard to the wire to which IMr. Richardson has referred, 
he is dealing with a nickel-iron alloy wire, I assume, with a high 
nickel content. Nickel and chromium form a eutectic alloy, which 
melts below 1,300° C, and in his case a ternary alloy is probably 
formed. It is an entirely different material from cold-rolled 
iron which my data cover. As to the nickel-steel buckets, to which 
I referred in my paper, I wish to make clear that the data given 
in this paper do not deal with the rate of penetration of chromium 
in nickel steel, but only in cold-rolled iron. I have no accurate 
data on the diffusion of chromium into nickel steel or nickel-iron 
alloys of high nickel content at 1,100° C, but I do know that it 
is possible to chromize pure nickel in this same way and at lower 
temperatures, and that chromized nickel steel resists corrosion to 
a marked degree. 

You can chromize many other metals. In fact, this diffusion 
of metals at high temperatures and below their melting points 
occurs generally. This is a wide field for investigation and little 
is known about what is really going on outside of the fact that 
diffusion takes place. 



A pafer presented at the Forty-thira 
General Meeting of the American Elec 
trochemical Society held in New York 
City, May 5, 1923, Dr. F. M. Becket in 
the Chair. 



THE PREPARATION OF PLATINUM AND OF PLATINUM-RHODIUM 
ALLOY FOR THERMOCOUPLES.' 

By Robert P. Neville.* 

Abstract. 
The Bureau of Standards has prepared in its laboratories 
thermo-element platinum and platinum-rhodium alloy for standard 
thermo-couples, to determine what performance might justly be 
required of such instruments. Melting of the pure metal and 
of the alloy was carried out in an Ajax-Northrup high frequency 
induction furnace, in crucibles of lime or thoria. Platinum and 
platinum-rhodium alloy, superior in quality to the best material 
of this kind formerly in the possession of the Bureau, was 
prepared. 



I. INTRODUCTION. 

One of the essential properties of thermocouples is constancy 
of calibration. Deficiencies in this property may be due to several 
causes, chief among which are inhomogeneity in the alloy wire 
and contamination of either the pure metal or the alloy. Deterior- 
ation may be due either to introduction of impurities during use, 
which is especially true of rare-metal couples, or to impurities 
in the metal and alloy from which the thermocouple was made. 
Lack of constancy in calibration caused by contamination during 
use may be prevented by proper precautions, but a solution of 
the problem when the deterioration is due to a lack of sufficient 
purity in the original metals is less easily attained. 

As a part of its general investigation of the metals of the 
platinum group the Bureau of Standards was desirous of making 

' Published by the permission of the Acting Director of the Bureau of Standards of 
the U. S. Department of Commerce. Manuscript received February 2, 1923. 
* Associate chemist, Bureau of Standards, Washington, D. C. 

371 



372 ROBERT P. NEVILLE. 

up in its own laboratories standard rare-metal thermocouples to 
determine what performance might justly be required in such 
instruments. 

II. MELTING TECHNIQUE. 

r 1. Requisites: Platinum melting is usually done with an oxy- 
hydrogen or oxy-gas flame on a fire-clay or lime refractory. 
When extreme purity of the fused metal is of utmost importance, 
the method of heating and the composition of the crucible must 
be considered with respect to other conditions than simply re- 
fractoriness and sufficiently high temperature. In addition to 
possessing the usual necesssary refractory qualities, the container 
in which pure platinum is melted should be a material free from 
all substances which might alloy with the metal, either directly 
or after reduction by the molten platinum. It also must be a 
material which does not appreciably dissociate when heated to 
very high temperatures under vacuum. 

The first essential of a method of heating is the attainment 
of the temperature at which platinum melts, but in addition to 
this the method also must be such as not to promote decomposi- 
tion of the refractory. Calcium oxide is sufficiently reduced 
by an oxy-hydrogen flame, especially if the flame is deficient in 
oxygen, for calcium to be detected in the platinum thus melted. 
Other oxides behave in a similar manner. The method of heating, 
therefore, must be such as not to favor the reduction of the 
refractory. 

^ 2. Furnace : The Ajax-Northrup high frequency induction 
furnace is particularly well adapted to the melting of pure plat- 
inum, and the preparation of platinum metal alloys. A descrip- 
tion of the furnace and a mathematical explanation of the theory 
of its method of heating may be found in a paper by Dr. 
Northrup.^ A small inductor coil especially adapted to melting 
small amounts of platinum was made for this work. It differed 
from the usual coils only in size, the inside diameter being 3 cm., 
and the length 10 cm. A 25 kva. converter supplied the high 
frequency current. 

3. Refractories : Molded crucibles of the necessary size, shape 
and composition were not available. Hand tamped crucibles, 

» E. F. Nortliiiip, Tians. Am. Electrochem. Soc. 35, 09-158 (1919). 



PREPARATION OF PLATINUM FOR THERMOCOUPLES. 373 

usually either of lime or thoria, were made from materials pre- 
pared in the Bureau's laboratories for this purpose. 

Calcium oxide has the advantage of being the least expensive 
and the most easily purified of the refractory materials tried. 
Its use is advantageous for small melts where solidification of 
the metal is allowed to take place in the container. The crucibles 
are less troublesome to make, the resulting ingots may be easily 
cleaned with hydrochloric acid, and the quality of the metal 
produced compares favorably with the best. The special purifi- 
cation of the material employed at the beginning of the work was 
later found unnecessary. The oxide obtained by igniting "c. p." 
calcium carbonate at about 1000° C. in an electric muffle furnace 
was found just as satisfactory. 

The thoria used was prepared from the "c. p." nitrate of com- 
merce by successive precipitations as Th(OH)4 and finally as 
the oxalate, and ignition in an electric muffle furnace at about 
1000° C. Calcination at a higher temperature would have been 
desirable, but means of obtaining a higher temperature without 
danger of contamination were not available. It was necessary 
to use thoria whenever large quantities of the purest metal attain- 
able were desired, or whenever the melt was to be poured. Cruci- 
bles of thoria have a high density, and unusual mechanical 
strength for an unsintered material. Their very low thermal 
conductivity makes them more suitable than lime for large melts, 
where the heat capacity is much greater. Ingots melted in thoria, 
however, are very troublesome to clean. Several fusions in 
potassium pyrosulfate are necessary to dissolve the refractory 
still remaining after all possible has been removed by mechanical 
means. 

The best lot of platinum that has been prepared up to the 
present time was melted in thoria. It was found to be 10 micro- 
volts thermoelectrically negative at 1200° C. to the Bureau's 
standard, known as "K." This standard, K, was a melt made in 
lime and was 45 microvolts negative at 1200° C. to the best 
Heraeus thermo-element wire formerly used as a standard. This 
later melt in thoria then superseded K as a standard. 

Zirconium oxide, if pure, would probably serve as well as 
thoria. A few melts were made in zirconium oxide prepared by 



374 ROBERT P. NEVILLE. 

igniting Kahlbaum's zirconium nitrate in an electric muffle fur- 
nace. Platinum melted in crucibles of this oxide was about 30 
microvolts positive to the standard then used, or 40 microvolts 
positive to the present standard. The number of these melts was 
insufficient to justify definite conclusion as to its suitability. 

The same general method of making crucibles was used for 
the different refractory materials. The procedure was that of 
tamping the refractory in a cylindrical crucible of alundum of 
very thin walls. Thoria, in the dry powdered form, is sufficiently 
coherent when slight pressure is applied for crucibles to be made 
without moistening. Calcium oxide packs less easily, so this 
material was moistened with petroleum ether. The hydration of 
calcium oxide necessitated the use of petroleum ether, but it 
was also used with thoria or zirconia if moistening was necessary, 
because of its rapid evaporation and the consequently quick 
drying of the crucible. The mandrel was removed after tamping, 
and if the material was thoria, the crucible was ready to use. 
Lime crucibles were dried and lightly calcined. 

4. Melting: A number of experiments were made to deter- 
mine the best method of heating, and to work out details of 
melting and crucible making. The melting of previously fused 
platinum in the induction furnace was a simple matter so far 
as ability to obtain the necessary temperature was concerned. 
The melting of sponge, however, was found to be more difficult. 
Sponge could be quickly heated to about 1500° or 1600° C, but 
it was very difficult to continue heating from this point up to the 
melting point of platinum. If the sponge was compressed it 
would then heat as readily as the solid platinum. The method 
tried first was to melt a small piece of the compressed sponge 
and then to add to this the remainder of the platinum as un- 
compressed sponge. The time required for the addition of this 
uncompressed sponge allowed excessive shrinkage of the refrac- 
tory, and thereby frequently caused failure and loss of the melt. 
For this reason it was found more satisfactory to compress all 
the sponge into pellets. 

The compression block used for this purpose was a steel cylin- 
der of uniform diameter, highly polished and "glass" hard on 
the inner surface, closed with a tightly fitting plug at one end 



PREPARATION OF PLATINUM FOR THERMOCOUPLES. 375 

and a removable plunger at the other. With the plug in place 
the block was filled with sponge and the plunger inserted. Pres- 
sure was applied to the plunger until the sponge was compressed 
into a compact mass, after which the plug was released and the 
pressure reapplied which forced out the plug followed by the 
pellet of platinum. The cylindrical pellets made in this manner 
were 1 cm. in diameter and about 1.5 or 2 cm. long. They had 
the bright metallic appearance of fused metal and possessed 
sufficient mechanical strength so that no particular care was 
necessary in handling them. 

Experiments were carried out varying the rate of heating, the 
temperature of the melt, length of time the melt was kept molten, 
and the number of repeated meltings. In these experiments the 
metal was allowed in every instance to solidify in the crucible in 
which it was made. Superheating to any extent was found not 
only to be of no advantage but undesirable, and to subject the 
melt to danger of loss through shrinking and cracking of the 
refractory. Excessive heating increased liability of contamina- 
tion. The method found to produce the best results consisted in 
a rapid heating to a temperature just below the melting point, 
followed by a much slower heating to fusion. After dropping 
the temperature so as to permit partial solidification, and re- 
melting two or three times with alternate scant solidification, the 
metal was allowed to cool slowly to below the freezing point. 
The slower rate of heating just before fusion kept the tempera- 
ture from suddenly running up too high when the metal melted. 
Likewise there was more certainty that the metal was not being 
heated to an excessive temperature when, instead of being kept 
continuously molten, it was remelted several times with alternate 
scant solidification. If the temperature was allowed to run too 
high, or the metal kept molten an excessively long time, shrinkage 
took place in the refractory (especially if it was thoria), which 
allowed cracks to develop into which the metal would run, and 
cause the ingot to have an irregular shape and uneven surface. 
A calcination of the refractory at a higher temperature would 
have been a means of preventing this, if calcination could have 
been accomplished without contamination. A method of calcining 
thoria crucibles under vacuum in a tungsten shell will be discussed 
below. 



376 ROBERT P. NEVILLE. 

Several experimental melts were carried out in which attempts 
were made to control shrinkage cavities by regulating the method 
of solidification, so as to obtain progressive freezing of the ingot 
from the bottom toward the top. In this manner the diminution 
in the volume of the metal upon transition from the liquid to 
the solid phase could be localized at the top of the ingot. The 
method of controlling the order of freezing consisted in cooling 
through the solidification temperature, by gradually lowering the 
crucible down through the furnace inductor coil without any 
change in the power input of the furnace. This progressive 
freezing of the melt was obtained by lowering the crucible through 
the inductor coil by means of a screw in the crucible support, the 
power input remaining unchanged during the process. The bottom 
thus began to cool first, and solidification was progressive from 
the bottom to the top of the ingot. Thus since the direction of 
freezing was entirely lengthwise in the crucible, the shrinkage was 
localized at the top, and any cavity was at the top rather than in 
the interior or on the side of the ingot. The method was not 
entirely successful, because the longer time required for solidifi- 
cation in this manner often caused the failure of the refractory 
and consequent loss of the melt. 

5. Casting : The preparation of platinum alloys introduces a 
difficulty which does not accompany the melting of pure platinum, 
namely, inhomogeneity in composition, resulting from selective 
freezing upon solidification. Selective freezing may be prevented 
by extremely slow cooling with stirring, or by so sudden a tran- 
sition from the liquid to the solid phase that segregation can 
not take place. Casting the melt in a chill mold is the obvious 
solution, hence the first requirement is a crucible of sufficient 
mechanical strength to permit pouring. This mechanical strength 
was not present in the crucibles used for melting pure platinum, 
where solidification took place in the crucible. This again brought 
up the question of a feasible method of calcining crucibles. 

The preparation of hard-burned crucibles from compressed 
refractory powders, without the calcination of the crucibles before 
their removal from the shells in which they were molded, was 
practically impossible. Tungsten seemed to be the only practical 
material in which this calcination could be carried out without 



PREPARATION OF PLATINUM FOR THERMOCOUPLES. 377 

detriment to the quality of the crucible. Graphite so used caused 
the formation of carbide in the refractory. Recent work* had 
shown that thoria is slightly reduced by tungsten at temperatures 
below 2300° C, but apparently not enough to interfere with its 
utilization for the present purpose. 

Crucibles were made by tamping thoria, previously calcined at 
1800° C, in cylinders of sheet tungsten. The thoria lined 
tungsten shells were calcined in an electric vacuum furnace to 
about 1800° C. The resulting sintered crucibles were very hard 
and possessed good mechanical strength, but as a precaution 
they were not used without the reinforcement of an outer crucible 
of alundum. Any space intervening between the thoria crucible 
and the alundum shell was filled in carefully with finely ground 
thoria. Castings were in a few instances made from uncalcined 
crucibles, but the fragility of the thoria was a source of annoyance. 

The melting procedure for casting was the same as usual except 
that, instead of allowing the melt to solidify in the furnace, the 
crucible was removed from the coil and the melt poured into 
a graphite mold, made by drilling out the desired ingot shape in 
a large block of Acheson graphite. 

A melt to be poured must be superheated somewhat more than 
one permitted to solidify in the crucible, or solidification will 
take place before pouring is possible, particularly when the 
melting has been done in a sintered crucible whose thermal 
conductivity is greater. The pouring temperature was kept as 
near the freezing point as possible, as high casting temperatures 
were found to cause unsoundness in the ingot. The amount of 
gas dissolved by the molten metal, especially the platinum-rhodium 
alloy, apparently increased as the temperature of heating was 
raised, which seemed to cause more blow holes on freezing. 
However, if the melt was held for a short time at the lowest 
temperature permitting pouring without premature freezing, little 
gas was evolved on solidification in the mold, and chances for a 
sound ingot were greater. 

III. MECHANICAL WORKING. 

1. Rolling: The ingots were rolled through 5 cm. (2 in.) 
diamond grooved hard steel rolls. The grooves were graduated 

* C. J. Smithells, Reduction of Thorium Oxide by Metallic Tungsten Tour 
Chem. Soc. (Lon.), 122, 2236 (1922), ^ ' •" 



37^ ROBERT P. NEVILLE. 

in size from 19 mm. (3/4 in.) square for the first to 2 mm. (5/64 
in.) for the last, which had slightly rounded corners. In order 
to prevent contamination during mechanical working particular 
care was taken to keep the roll surfaces in the best possible 
condition. Spectrographic analysis revealed no trace of iron in 
pure platinum after rolling. 

2. Draw'mg: Sapphire dies were used for drawing the wire 
from the 5/64-inch rod. Before drawing, the wire was cleaned 
by rubbing between filter paper saturated with alcohol to remove 
grease and any adhering flakes of metal. The reductions in the 
dies were 0.0076 mm. (0.003 in.) at each draft at the start. 
The last few drafts were slightly less. The final diameter of the 
wire was 0.63 mm. (0.0246 in.) 

Platinum is so malleable that unevenness of the ingot and many 
other defects may be rolled out and obscured. Such flaws pos- 
sibly may be cold-welded so that they are as sound as any portion 
of the metal, but since there was some uncertainty, discards were 
always made from both ends of the drawn wire. The wire was 
cleaned after drawing in the same manner as after rolling. 

IV. THERMO-ELEMENT PLATINUM. 

1. Sponge: The separation of the metals and the purification 
of the sponge will not constitute a part of this paper. It is 
assumed here that the materials melted were in every case of 
the highest degree of purity attainable. Preparatory to melting 
the sponge was pressed into small cylinders of sufficient density 
to permit heating by direct induction. 

2. Melting: Several different lots of platinum were melted 
with slight variations in method. This description will follow 
in detail the method of melting the best of the large ingots made. 

The melting was done in a thoria crucible made in an outer 
crucible of alundum as described above. Its inside diameter was 
slightly greater than that of the cylinders of compressed sponge. 
The cylinders of sponge were placed in the crucible, one on top 
of the other, until the crucible was full, and the whole set in the 
coil of the furnace ready for melting. The graphite mold was 
set a few inches away from the furnace, and the remainder of 
the compressed cylinders for the charge placed conveniently for 



PREPARATION OP PLATINUM FOR THERMOCOUPLES. 379 

quick addition after fusion had begun. The furnace was started 
at a power input of 5 kw. and reduced to about 4 kw. before 
fusion had begun, which usually occurred in about a minute. 
Quick adjustment of power input permitted ready control of the 
temperature of the melt. As the first part of the charge melted 
and sank the remaining cylinders were added. As soon as the 
mass was thoroughly liquid after all the sponge had been added, 
it was allowed to cool to superficial solidification and again melted. 

Two or three successive remeltings with alternate superficial 
solidification were a means of preventing unintentional super- 
heating, and at the same time assured that the time the melt was 
molten was long enough for the volatihzation of any remaining 
salt or other foreign matter in the sponge. Upon melting the 
last time the temperature was carried on up until judged high 
enough for the metal to remain liquid until it could be poured. 
The power was cut ofif, the crucible removed with tongs and the 
melt poured as quickly as possible. Solidification was almost 
instantaneous. 

The main body of the ingot was about 1 cm. in diameter and 
6 cm. long. The top part of the mold was of a larger diameter 
so as to provide for a head which would solidify last and confine 
the shrinkage cavity to the top. The ingot (124 g. in weight) 
was sound, of smooth surface, and with no sign of a defect. 
The shrinkage cavity on solidification was localized at the top 
of the head, which was cut oflf before the mgot was rolled. 

3. Wire : Since this ingot was cast, no cleaning was necessary 
before rolling as was the case when the melt was allowed to 
solidify in the furnace. Pure platinum is so ductile that rolling 
and drawing are simple matters. A slight contamination of 
very pure platinum noticeably increases the hardening resulting 
from the cold working during drawing. After roUing and draw- 
ing to 0.63 mm. (0.0246 in.) wire, without any annealing during 
the process, the pure platinum wire was still soft. After cleaning 
and making discards from the ends, the wire was ready for 
testing and cutting into convenient lengths for thermocouples. 

Spectrographic analysis failed to reveal the presence of any 
impurit}\ Results of thermo-electric comparisons and service 
tests are discussed below. 



380 ROBERT P. NEVILLE. 

V. THERMO-ELEMENT ALLOY. 

1. Materials and Melting: The platinum sponge used in mak- 
ing the 90 per cent platinum- 10 per cent rhodium alloy was the 
same as that used for the platinum element, and was handled in 
the same way. The rhodium, however, was not added as sponge 
but in the form of a fused ingot. The rhodium sponge, approxi- 
mating in weight a tenth of the total weight of alloy to be 
made, was compressed into a cylinder and fused under vacuum. 
This preliminary vacuum fusion eliminated any gaseous and 
volatile matter in the sponge and facilitated the addition of a 
definite amount of rhodium to the melt. 

The melting procedure for the rhodium differed little from the 
melting of pure platinum. The crucible was of powdered cal- 
cium oxide pressed into a shell of alundum. This crucible, con- 
taining the compressed rhodium sponge, was placed in the bottom 
of a closed-end hard glass tube and set in the coil of the induc- 
tion furnace. The rhodium was fused under vacuum, held molten 
a few minutes, and allowed to cool in the crucible while the 
vacuum was maintained. 

The charge was then accurately calculated on the basis of the 
weight of the cleaned rhodium ingot, the platinum weight being 
nine times the weight of rhodium. In melting the alloy the pro- 
cedure Avas the same as described above for melting pure platinum. 
The rhodium ingot was dropped in while the platinum was molten 
so it would dissolve quickly and not be exposed to the air long 
while at a high temperature. The method of pouring the alloy 
differed from that of pure platinum only in that more care had 
to be taken that the alloy was not too hot when poured ; otherwise 
an unsound ingot resulted. 

2. Wire: The alloy was rolled and drawn to 0.63 mm. 
(0.0246 in.) wire in the same manner as the pure platinum, 
except for annealing, which was unnecessary with the latter. 
The alloy hardens more with deformation than pure platinum, 
so it was annealed at frequent intervals during the mechanical 
working. The finished wire was as smooth and uniform as the 
pure platinum wire. 

The alloy was tested spectrographically for contamination, with 
negative results. Xo difficulty was experienced in preparing 



PREPARATION OF PLATINUM FOR THERMOCOUPLES. 38 1 

alloys of the desired composition by direct synthesis. Complete 
homogeneity, however, was the doubtful point, so thermo-electric 
tests were made to detect any inhomogeneity in composition. 
Careful thermo-electric comparisons made at frequent intervals 
along the entire length of the wire indicated a maximum dif- 
ference in composition corresponding to less than 1° at 1200° C. 
In lengths suitable for thermocouples there was no significant 
difference in e.m.f. between the opposite ends. 

VI. SERVICE TEST. 
One of the thermocouples made as described and designated 
as CI was subjected to continuous heating. After a flash an- 
nealing, which consisted in heating the cold-drawn wire to about 
1500° C. by the momentary passage of an electric current, the 
couple was compared with the standard couple. It was then 
heated for 25 hours at about 1600° C. by passing an electric 
current through the wire suspended in air, and again compared 
with the standard. The platinum and alloy were found to have 
dropped 5.5 and 14.5 microvolts, respectively, at 1200° C, the 
equivalent of less than 1° C, which is about the usual drop noticed 
upon annealing preparatory to calibration. 

Life tests made at the Bureau on thermocouples of commercial 
manufacture have shown that the usual change in calibration 
resulting from 18 to 24 hours heating at 1500° to 1600° C. sub- 
sequent to preliminary annealing is from 3° to 10° C. 

Upon calibrating CI, subsequently to the treatment mentioned 
above, its calibration curve was found to be almost identical with 
the standard temperature-e.m.f. curve for platinum-platinum- 
rhodium thermocouples as given by the Geophysical Laboratory 
of the Carnegie Institution.'* 

VII, SUMMARY. 

1. As part of its general investigation of the platinum metals 
now in progress, the Bureau of Standards desired to prepare 
in its own laboratories standard rare-metal thermocouples in 
order to determine what performance might justly be required 
of such instruments. 

6 Adams, Bull, A. L M. M. E., 159, 2111 (1919). 



382 DISCUSSION. 

2. A method of melting was developed which consisted in 
fusing the sponge in crucibles of pure thoria or lime by means 
of an Ajax-Northrup high frequency induction furnace. The 
crucibles were made by tamping the powdered material around 
a mandrel in an outer crucible of alundum or tungsten. The 
melts of alloy were cast in a chill mold and those of pure platinum 
were usually allowed to sohdify in the furnace. 

3. Platinum and platinum-rhodium alloy superior in quality 
to the best material of this kind formerly in the possession of 
the Bureau were prepared. Thermocouples were made from 
this material which drop])ed off on 25 hours heating at about 
1600° C. the equivalent of about 1° C. 

The author wishes to make several acknowledgments. The 
preparation of the platinum and rhodium sponges was done by 
E. Wichers, chemist; the spectrographic analyses were made by 
W. F. Meggers, physicist ; the thermocouple service test was made 
by W. F. Roeser, laboratory assistant ; the entire work was con- 
ducted under the supervision of E. Wichers and Louis Jordan, 
chemist. 

Other papers dealing with the investigation of platinum metals 
by the Bureau of Standards are as follows: 

G. K. Burgess and P. D. Sale. A Study of the Quality of Platinum 
Ware, Bureau of Standards Sci. Papers, No. 254. 

G. K. Burgess and R. G. Waltenberg, Further Experiments on the 
Volatilization of Platinum, Bureau of Standards Sci. Papers, No. 280. 

L. J. Gurevich and E. Wichers, Comparative Tests of Palau and Rho- 
tanium Ware as Substitutes for Platinum Laboratory Utensils, Ind. Eng. 
Chem. 11, 570 (1919). 

E. Wichers, The Preparation of Pure Platinum, J. Am. Chem. Soc 
43, 1268 (1921). 

E. Wichers and L. Jordan, Investigations on Platinum Metals at the 
Bureau of Standards, Trans. Am. Electrochem. Soc. This volume. 



DISCUSSION. 

H. K. Richardson^ : The author says that the preparation of 
hard-burned crucibles from compressed refractory powders, with- 
out calcination of the crucibles before their removal from the 
shells in which molded, is practically impossible. We have been 
using thoria crucibles the last year or so, which were made by 

* Westinghouse Lamp Works, Bloomfield, New Jersey. 



PREPARATION OF PLATIXUM FOR THERMOCOUPLES. 383 

practically standard methods of the ceramic art, i. e., by casting 
and also by pressing methods. In both cases we have, by suit- 
able calcination and burning, obtained a crucible which has a 
perfectly smooth surface, and to which we have found, in one or 
two cases, that platinum scrap when melted does not adhere. 

So far we have not been able to make a crucible larger than 2 
inches in diameter by 6 inches long. These crucibles, when 
made in a furnace of the carbon-plate resistance type, are not 
satisfactory for use in induction furnaces, because they take up 
carbon from the atmosphere of the furnace and do not make a 
satisfactory container at 2,200 to 2,500° C, due to conducting the 
current and breaking down. 

These crucibles were made up for uranium research. One 
crucible has been carried to approximately 2,500° C. at least seven 
times. Molten material at this temperature has dropped into 
the crucible without cracking same, showing in a practical way 
their low coefficient of expansion. Under this condition of use 
they do not soften or lose shape. 

In the manufacture of the crucible, the thoria is very sensitive 
to taking up various materials ; but after once being made, except 
for metallic iron in an oxidizing atmosphere, the metals do not 
seem to react much with the crucibles. 

H. T. Reeve-: Has Dr. Jordan ever tried working down a bar 
of sintered platinum to wire. Melting seems unnecessary when 
it requires such troublesome methods to prevent contamination. 

F. E. Carter^: What does Dr. Jordan mean by the inhomo- 
geneity of the wire? Does he mean that one end of a thermo- 
element wire has a different composition from the other, or that 
there is coring of the crystals? 

Also, on page 372, it is stated that "the container in which pure 
platinum is melted should be a material free from all substances 
which might alloy with the metal, either directly or after re- 
duction by the molten platinum." Actually, if you use the oxy- 
hydrogen flame, and under oxidizing conditions, the purity of 
the lime crucible does not seem to be of much importance. The 
impurities are taken out of the platinum by the lime rather than 
the impurities of the lime by the platinum. I have found, for 

- Western Electric Co., New Yorlc City. 

= .Afetallurgist, Baker & Co. Inc., Newark, N. T. 



384 DISCUSSION, 

instance, I could get a purer platinum by melting in a lime cruci- 
ble with oxy-hydrogen flame, making sure it is thoroughly oxi- 
dizing, than by using the high-frequency induction furnace. 

When the metal is cast into a graphite mould, has the author 
ever had any indication of the platinum being attacked by the 
carbon? Is a carbide formed under these conditions? I notice 
the author used a closed end, hard-glass tube when working with 
a vacuum in the high-frequency furnace. I have found it more 
convenient to work the other way around, /. e., to use the ordinary 
vitreosil insulator closed by a disc of transparent quartz at the 
top, and evacuate at the bottom. 

Louis Jordan*: In regard to making the crucibles, Mr. Rich- 
ardson calls attention to the statement that it is practically im- 
possible to make them by ordinary methods. Since the preparation 
of Mr. Neville's paper, work with methods of casting the cruci- 
bles has been in progress. 

With regard to reaction with tungsten, there is a reference at 
the bottom of page Z77 to the reduction of thorium oxide by 
metallic tungsten. The work cited was at a somewhat higher 
temperature than that employed for the platinum melting, and 
at 1,800° C. we did not notice any reaction between the tungsten 
and the thoria. This was a thoria-Hned tungsten shell, rather 
than a tungsten-lined thoria. It was calcined in an Arsem fur- 
nace, but we found no decrease in the purity of the platinum 
melted in such crucibles, and no apparent change in the crucible 
indicating contamination by carbon. 

It is, of course, not necessary actually to melt the compressed 
platinum sponge. That is an European practice, I believe. It was 
not difficult to melt the compressed platinum sponge. A consid- 
erable charge of platinum sponge was melted in a high-frequency 
induction furnace in a few minutes, and it was as easy to melt 
completely as to sinter and hammer the metal sponge. 

We did not find any trouble in casting the pure metal or its 
alloys in Acheson graphite moulds. The mould was a chilled 
mould for the amount of metal we used, and freezing took place 
instantly and without, as far as we could see, any reaction with 
the carbon, 

* Bureau of Standards, Washington, D. C. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in Nciv York 
City, May 5, 1923, Dr. F. M. Becket in 
the Chair. 



INVESTIGATIONS ON PLATINUM METALS AT THE BUREAU 
OF STANDARDS.^ 

By Edward Wickers^ and Louis Jordan.' 

Abstract. 
The Bureau of Standards has vmdertaken a comprehensive 
investigation of the platinum metals, involving the purification 
of all metals of the platinum group, critical studies of analytical 
separation of the platinum metals, the melting and mechanical 
working of the pure metals and their alloys, the study of selected 
alloys with respect to their suitability for platinum ware, and the 
determination of a variety of physical properties of such metals 
and alloys. The first three phases of this investigation are 
actively in progress ; the last two phases are to be undertaken in 
the immediate future. 



I. INTRODUCTION, 

A considerable amount of work on platinum and platinum 
group metals has been carried out or is in progress in various 
divisions of the Bureau of Standards. It is believed that it will 
be of interest to give a brief account of this research, and call 
to the attention of those interested the activities of the Bureau of 
Standards in this field. It is the Bureau's desire to assist both 
users and the manufacturers in improving the standards of 
quality and performance of platinum and platinum alloy products. 

The importance of platinum and platinum metals for chemical 
laboratory ware, catalysts, resistance thermometers, thermo- 
electric pyrometers, electrical contacts, dental alloys, standards of 
mass and length, as well as their wide use in jewelry and in 

* Published by permission of the Acting Director, Bureau of Standards, Department 
of Commerce. Manuscript received February 2, 1923. 

* Chemists, Bureau of Standards. 

385 



386 EDWARD WICHERS AND LOUIS JORDAN. 

numerous other miscellaneous but important applications, are all 
too well known to require more than mention. 

1. Beginning of Platinum Work at the Bureau of Standards. 

In 1910 the American Chemical Society formed a committee 
on quality of platinum laboratory utensils, with Dr. W. F. 
Hillebrand, chief of the division of chemistry of the Bureau of 
Standards, as chairman. This committee made two reports, the 
first in 191 P and a supplementary one in 1914.* In the first 
report were summarized the principal difficulties experienced 
with laboratory ware at that time, namely, (1) undue loss of 
weight on ignition; (2) undue loss of weight on acid treatment, 
especially after ignition; (3) discoloration, crystallization, or 
frosted appearance of the surface after ignition; (4) adherence 
of crucibles to platinum triangles after ignition; (5) alkalinity of 
surface after ignition; (6) blistering; (7) development of cracks 
after continued heating. 

Following the suggestions of this committee as to points 
requiring investigation. Burgess and Sale,"* of the Bureau of 
Standards, determined losses on ignition and on treatment with 
acid for a number of platinum utensils. In order to show the 
relation of these losses to the composition of the platinum ware, 
they developed a thermoelectric test for purity, a test which did 
not injure the article tested, and which furnished data which 
made it possible to classify the metal in terms of its content of 
iridium, at that time the most common impurity or alloying 
element. 

This method consists in clamping or arc soldering two pure 
platinum wires to opposite sides of a platinum dish or crucible 
and connecting these wires with a millivoltmeter. With one 
junction at room temperature or cooled in an air jet, the other 
junction was heated in a small blast flame to a definite tempera- 
ture, say 1,100° C, and the thermoelectromotive force of the 
impure platinum of the crucible against the pure platinum wire 
was read. From a chart of isothermal curves of electromotive 
force in millivolts against the percentage of iridium alloyed with 
platinum, the amount of impurity in the crucible was found in 

'J- Ind. Eng. Chem., 3, 686-91 (1911). 
*J. Ind. Eng. Chem., 6, 512-13 (1914). 
» B. S. Scientific Papers No 2.54; 1915. 



INVESTIGATIONS ON PLATINUM METALS. 387 

terms of the equivalent iridium content. The crucibles tested for 
losses on ignition and acid treatment were then classified accord- 
ing to their iridium content or in one or two instances accord- 
ing to their rhodium content, when this was known to be the 
alloying and hardening element. 

Burgess and Waltenberg" carried out further tests on the vola- 
tilization of platinum, working over a range of temperatures 
from 700 to 1,200° C. In testing for volatilization losses the 
ware was heated in an electric resistance furnace, but always with 
a stream of air passing through the heated chamber, since losses 
in weight of platinum on ignition seem to be influenced by the 
presence of oxygen. The data obtained from these experiments 
indicated that above 900° C. the volatilization of platinum con- 
taining iridium was greater than that of pure platinum, and 
increased with the iridium content and with temperature ; the 
loss of platinum containing rhodium was less than for pure 
platinum at all temperatures. 

2. Present Need for Research on Platinum Metals. 

It was not possible for the platinum committee to obtain 
reliable information as to the composition of platinum ware 
further than that given by the thermoelectric test. That is to 
say, qualitative information as to the nature of the impurity 
could not be obtained, and little could be done in correlating 
composition with quality of service in the absence of definite 
knowledge of the nature of the impurities. 

The committee in their supplementary report outlined in the 
following sentences the procedure which seemed to them desira- 
ble in continuing work on the quality of platinum ware. ''This in- 
formation . . . can be gained only by carrying out an elabo- 
rate investigation involving the preparation of the pure metals 
and some of their alloys, and also by the careful analysis of 
commercial ware. It is hoped that in time the Bureau of Stand- 
ards may be able to take up such an investigation. . . . The 
investigation should not be restricted to a study of the subject 
from the point of view of the chemist alone, but should be made 
comprehensive as to the physical behavior of the metals and their 
alloys so that all users of platinum might benefit." 

•B. S. Scientific Papers No. 280; 1916. 



388 EDWARD WICKERS AND LOUIS JORDAN. 

II. CURRENT INVESTIGATION OF PLATINUM METALS. 

The Bureau of Standards has recently been able to commence 
this comprehensive investigation of platinum metals. The major 
phases of this work are the preparation of all the platinum metals 
in a state of very high purity ; the development and critical 
examination of methods of analysis, not only chemical, but also 
spectrographic and thermoelectric methods ; the development of 
the technique of melting and mechanical working of metals and 
alloys of extreme purity ; the preparation and testing for quality 
of platinum laboratory ware of accurately controlled composition, 
the determination of selected physical properties of metals and 
alloys of composition identical with the ware, and the correlation 
of composition, physical properties, and quality of service ; the 
determination of the most important physical constants and the 
physical and chemical behavior of all available platinum metals 
and alloys in so far as the facilities of the Bureau permit. 

1. Purification of Metals. 

It is obvious that the first essential in an investigation such as 
was just outlined is the preparation of each of the platinum 
metals in the highest possible degree of purity. This important 
feature has been neglected too often in the past, and to this 
neglect are undoubtedly due many of the questionable data on 
physical properties found in the literature. This work of purifica- 
tion has already progressed to a stage where quantities of each 
metal, except ruthenium, sufficient for our immediate needs have 
been prepared. Ruthenium has been omitted thus far because 
its scarcity probably will prevent any extensive application. 

The purification of platinum and palladium has been reduced 
to a routine procedure. A preliminary paper on pure platinum 
has been published, this paper dealing particularly with the con- 
tamination of platinum with calcium when the metal is melted in 
lime crucibles under unfavorable conditions.'' The preparation 
of pure osmium, involving a new method for converting osmium 
tetroxide to quadrivalent osmium chloride, will be published 
shortly in connection with the re-determination of the atomic 
weight of osmium, the latter work having been done at The Johns 
Hopkins University. 

'E. Wichers, J. Am. Chem. Soc, 43, 1268 (1921). 



INVESTIGATIONS ON PLATINUM METALS. 389 

The Study of methods of purification has developed consider- 
able material suitable for publication, but which will first be 
supplemented with additional work. It may be stated that the 
simple process of repeated precipitation with ammonium chloride 
is an entirely feasible method of purifying platinum. The exist- 
ing literature contains but little useful information on the puri- 
fication of most of the platinum metals, especially iridium and 
rhodium. 

It was realized from the first that the presence of very small 
quantities of impurities in the metals prepared would have to be 
detected by other than chemical methods. For this purpose spectro- 
graphic analysis, and the comparison of thermoelectric force, and 
the coefficient of electrical resistance, have been used with much 
success. Spectographic examination has been applied to all of 
the metals, but the other two methods have been applicable only 
in the case of palladium and platinum, the two metals which can 
be readily drawn into wire. 

Thermoelectric comparison has been found to be particularly 
useful in controlling the purification of platinum. Observations 
are made at an approximately fixed temperature (1,200° C.) 
against an arbitrary standard. Readings can be completed in a 
few minutes, and the sensitiveness is far in excess of the require- 
ments. The e. m. f. can be measured to tenths of microvolts 
without difficulty, and dififerences of 10 or even 15 microvolts 
can hardly be interpreted in terms of a definite impurity even by 
means of the spectroscope. All evidence indicates, however, that 
the purest samples (as prepared from the usual sources) are 
the most negative. The best samples of platinum thus far pre- 
pared gave an e. m. f . of about 30 microvolts negative to the best 
material (consisting of a single sample) to which the Bureau 
had had access previously. One of these best samples is now 
used as the standard for thermoelectric comparison, and all 
platinum prepared is required to give an e. m. f . of not more than 
15 microvolts positive to this sample at 1,200° C. 

A series of alloys of rhodium in platinum and one of iridium 
in platinum, both from 1 per cent down to 0.001 per cent, were 
prepared to determine the thermoelectric behavior of dilute 
alloys toward pure platinum. It was found that in these two 
series the variation in e. m. f. was directly proportional to com- 



390 EDWARD WICHE;RS and LOUIS JORDAN. 

position ; that is, the isothermal curve of e. m. f . plotted against 
composition was practically a straight line, for alloys up to 1 
per cent.* Thermoelectric comparison has been applied in a 
similar way to palladium, particularly to the metal which is being 
used to determine the palladium melting point on the optical 
scale of temperature. 

Less use has been made of the determination of the cqefificient 
of electrical resistance. This method is far less sensitive than the 
thermoelectric comparison, takes more time, and so far as it has 
been used has not given much additional information. It is gen- 
erally accepted that the coefificient of resistance increases with 
increasing purity. The thermo element platinum purchased by 
the Bureau in the past few years has usually had a coefificient 
(between 0° and 100°) of about 0.003910, while one of a group 
of three samples, which were of a foreign manufacture, gave a 
value of 0.003917. A sample of American manufacture, recently 
received, gave a value of 0.003906 as received, and 0.003917 after 
heating at 1,500° for several hours. Samples of platinum pre- 
pared at the Bureau have given a coefificient up to 0.003917 as 
drawn and up to 0.003922 after a period of heating such as that 
just described. 

This method as well as the thermoelectric comparison fails to 
give any information as to the nature of the impurity or impuri- 
ties which are present. For this purpose the method of spectro- 
graphic analysis is used. The application of this to platinum has 
been described by Meggers, Kiess and Stimson.^ The sensitive- 
ness of the method to the most persistent impurities was deter- 
mined by examining series of progressively diluted alloys, down 
to 0.001 per cent. It is believed that the presence of 0.001 per 
cent of any of the usual impurities in the platinum metals can 
be detected in the spectrogram. The aim in routine purification 
is to prepare material which shows no lines of any impurities, 
except in some cases the faintest lines of the elements in the 
refractories used for melting. Sometimes even these can be 
eliminated. 

Table I will serve as an illustration of the way in which 
spectrographic analysis and the thermoelectric comparison were 

' C. O. Fajrchild. Communication to the Philosophical Society of Washington, 
Feb. 11. 1922. 

• B. S. Scientific Papers No. 444, "Practical Spectrographic Analysis;" 1922. 



INVESTIGATIONS ON PLATINUM METALS. 



391 



used in the control of the process of purification. No. 94 
is a sample taken from a 500-g. lot of sponge of commer- 
cial purity purchased from an American refiner. No. 95 
is metal from the first precipitation of ammonium chloroplatinate. 
No. 96 is from the second and No. 105 is from the third and last 
precipitation. All were melted in pure lime in the induction 
furnace, as will be described in a subsequent part of the paper. 

The values for e. m, f. are those found against our standard at 
1,200° C. The values are given in microvolts and all are positive. 
The figures given in the spectrographic analysis are intensities 
estimated relative to those of platinum lines, the faintest of which 
are designated as 1 and the strongest as 10. These values are not 
interpreted in absolute proportions present, except that the "trace" 
of rhodium in No. 96 is estimated as less than 0.001 per cent. 



Table I. 

Results Obtained in Purifying Platinum. 

Thermo clcciric Comparison. 





No. 94 


No. 95 


No. 96 


No. 105 


e. m. f 


442 


57 


24 


8 


Spectrographic Analysis. Figures indicate estimated relative intensities. 



Palladium 
Rhodium . 
Copper . . . 
Iridium . . . 
Ruthenium 

Iron 

Tin 

Lead 

Calcium . . 



3 


2 


1 — 





1 


1 — 


trace 





1 


trace 




































































trace 


trace 


trace 


trace 



It is interesting to note that the original source of this platinum 
was probably platiniferous copper or nickel ore, rather than 
alluvial platinum deposits. This is indicated by the predominance 
of palladium among the impurities and the absence of iridium. 

2. Analytical Methods. 
With a quantity of each of the pure metals (except ruthenium 
as noted) at hand, it became possible to undertake some of the 



392 EDWARD WICKERS AND LOUIS JORDAN. 

Studies contemplated when the work was begun. A critical 
investigation of analytical separations and methods of determina- 
tion seemed to be of prime importance, both as a means of pro- 
viding adequate control of the composition of alloys used in other 
phases of the general research, and because of the lack of 
accepted standard methods for the analysis of various articles of 
commerce containing one or more of the platinum metals. The 
evaluation of crude platinum metals, ore concentrates, catalytic 
masses, manufacturers' scrap and sweeps, and the control of com- 
position of alloys for electrical work, jewelry and dental work, 
are matters of every-day necessity in the platinum industry. 

The Bureau's study of analytical methods is at present directed 
mainly toward two problems. The first is the accurate determina- 
tion of iridium in platinum alloys, and the second an accurate 
and reasonably rapid method for the partial or complete analysis 
of crude platinum concentrates or native grain platinum. The 
work on the latter has been begun only recently, and may be said 
to show promise. The principal novel feature of the method is 
the avoidance of the separation of the concentrates into two 
fractions, respectively soluble and insoluble in aq^ta regia. If 
this is successful it will permit of the determination of total 
iridiuiTu rather than the portion which is insoluble in aqua regia. 
The high relative cost of iridium makes the proper evaluation of 
the native platinum important. 

The work on the determination of iridium in platinum alloys 
will be published shortly. No new method is proposed, but the 
old method of Deville and Stas is brought up to date, and made 
to conform to modern laboratory methods. The procedure con- 
sists of fusing the alloy with ten or more parts of lead, and 
parting the resulting lead ingot first with nitric acid and then 
with dilute aqua regia. The factors of temperature of the lead 
fusion, time of fusion, proportion of lead, and concentration of 
aqua regia used in the second parting, as well as the influence 
of the presence of iron, ruthenium, and rhodium have been care- 
fully studied. The method was found to be capable of giving 
results of great accuracy, except that slightly low results for the 
iridium content are obtained in alloys containing about 15 to 20 
per cent, corresponding to contact point metal. This error can 
be corrected by a second separation of iridium. It is proposed 



INVKSTIGATIONS ON PLATINUM METALS. 393 

to submit this method to commercial laboratories for comment 
before it is published. 

3. Technique of Melting and Working. 

(a) Refractories. The first method employed for melting the 
pure platinum sponge was the usual one of fusion on lime in an 
oxyhydrogen blast flame. Calcium was always detected in metal 
melted in this manner. Contamination by calcium was serious 
■ whenever the blast was allowed to become deficient in oxygen 
while the metal was molten.^" Platinum melted in lime in the 
Ajax-Northrup high-frequency induction furnace, with free 
access of air and without excessive superheating, was of satis- 
factory purity as determined by the thermoelectric tests. 
although spectrographic evidence of calcium usually was found. 

Small quantities of platinum melted on pure magnesia in the 
oxy-hydrogen flame with an excess of oxygen were of high purity. 
Melts of platinum in magnesia in the induction furnace were 
seriously contaminated with magnesium when a graphite or 
tungsten shell was used outside the refractory liner. The reduc- 
tion of the refractory may have been caused by the carbon or 
carbon monoxide or by the metallic tungsten. However, a con- 
sideration of the qualities required in a refractory for general use 
in melting the metals of the platinum group and their alloys, led 
to the belief that thorium or zirconium oxide should be more 
satisfactory than lime or magnesia, and tests with magnesia in 
the induction furnace were discontinued. 

Thorium oxide has an exceedingly high heat of formation, a 
high fusion point, low thermal conductivity, and can readily be 
made into refractory shapes of good mechanical strength without 
the use of any additional substance as a binder. It therefore gave 
promise of being suitable for crucibles for melting all of the 
platinum metals, and of being little liable to dissociation at high 
temperatures and reduced pressures. These latter character- 
istics are required, because it is desirable to carry out the fusi.on 
of certain platinum metals in a vacuum, as in the case of palladium 
and rhodium. Thoria has been used as the refractory in all melts, 
both in air and in vacuum, when the highest purity was required. 

Xtvy pure zirconium oxide is difficult to obtain. The best 

'• See footnote 7. 

26 



394 EDWARD WICKERS AND LOUIS JORDAN. 

oxide available, prepared by ignition of Kahlbaum's zirconium 
nitrate, was used as the refractory in a few melts of platinum. 
The quality of the resulting metal as judged by the thermoelectric 
test was not as good as that of metal fused on lime or thoria. 

(b) Furnace. The high-frequency induction furnace proved 
to be a convenient and satisfactory means of melting platinum 
metals with the minimum contamination. The range of tempera- 
tures available is sufficient for melting the most refractory of the 
metals. Temperature control and the control of the atmosphere 
over the molten metal or melting under vacuum are easily accom- 
plished. ' Homogeneous alloys are readily made ; small melts can 
be cast in chill molds ; the location of shrinkage cavities can be 
controlled ; and a very accurate synthesis of alloys is possible. 

(c) Working of Platinum Metals. The mechanical working 
of the pure metals and alloys presents no particular difficulty 
in so far as contamination during rolling and drawing are con- 
cerned. Careful attention to the condition of the surface of steel 
rolls, and the use of jewel (sapphire and diamond) dies for wire 
drawing, allow satisfactory working. ^^lore complete details 
of the technique of melting and working as involved in the 
preparation of the Bureau's standard thermocouples are given 
in a paper by R. P. Neville to be presented at this meeting. 

4. Quality of Platinum Laboratory Ware. 

The results of the first three major phases of the general in- 
vestigation of the platinum metals, namely the purification of 
metals, methods of analysis, and melting and working technique, 
are rapidly becoming available. It is thus possible to undertake 
the study of platinum alloys with reference to their suitability 
for platinum laboratory ware. 

In the Bureau's experience, based on the small portion of its 
platinum laboratory ware purchased from commercial sources 
and on the few samples of ware submitted from other labora- 
tories for tests of quality, some of the difficulties mentioned in 
the platinum committee's first report are no longer so frequently 
encountered. The most serious point of failure in platinum ware 
at present seems to be the tendency to develop cracks after con- 



INXTiSTlGATIONS ON PLATINUM METALS. 395 

tinned heating. The causes of this failure and methods for its 
prevention are apparently unknown. 

The present plan for this portion of the general investigation 
is to determine mechanical and certain other physical properties 
of test specimens and crucibles made from selected platinum 
metal alloys, to make accelerated service tests, and to attempt 
to correlate the two series of data. 

5, Physical Properties of Platinum Metals. 

The preparation of the pure platinum metals and their alloys 
for the purposes of the several phases of the general investigation 
thus far outlined, provides an opportunity for the measurement 
of a variety of physical properties of such materials. The plat- 
inum metals have properties of unusual interest, and are in con- 
stant use in the prosecution of scientific investigations. Some 
of the data already reported in the literature are contradictory, 
and many more are doubtless incorrect or very inaccurate, both 
because of faulty measurements and because the degree of purity 
of the materials studied has frequently been ignored. 

In so far as the nature of the samples available from the 
preceding phases of this work and the facilities of the Bureau 
of Standards will permit, the more important electrical, thermal, 
optical, mechanical and various other miscellaneous physical 
properties of the pure metals and selected alloys of the platinum 
group will be determined. 

It is believed that the results obtained from the investigations 
outlined will be of interest and value to all users and manu- 
facturers of platinum. Manufacturers of platinum have already 
expressed their interest in this investigation. Detailed reports on 
the various phases of the research will be made as rapidly as 
the progress .of the work warrants. The Bureau will welcome 
correspondence or conference with both manufacturers and users 
of platinum, with a view to establishing closer contact with the 
outstanding problems of the industry. 



DISCUSSION. 
F. E. Carter^ : I have just two remarks to make. I do not 
altogether agree with the authors that the thermoelectric test is 

' Metallurgist, Baker & Co., Inc., Newark. N. J. 



396 DISCUSSION. 

better than the coetiicient of electrical resistance. I think that 
the figures given in the same paragraph show that you readily 
distinguish between the purity of platinum by the latter test. I 
would be interested to learn whether the Bureau is working out 
electrolytic methods of separation of the platinum metals, for 
I think the future lies along that line. Getting only partial 
separation and having to repeat the precipitation is a great 
nuisance in chemical separations. As an example of what I 
mean, Dr. Jordan states that the method for determining iridium 
in platinum was found capable of giving results of great accuracy 
except that slightly low results for the iridium content are ob- 
tained in alloys containing about 15 to 20 per cent, where actually 
greatest accuracy is required. 

The manufacturer does not take into account whether there is 
half per cent or one-third per cent of iridium in platinum ; in 
such cases he pays for platinum only. But if appreciable quan- 
tities are present it is different; he pays for the iridium, the 
amount of which he must know accurately, because the difference 
in price between iridium and platinum is great. 

I quite agree with the statement that in platinum ware the 
tendency to develop cracks upon continued heating is serious. 
This cracking appears to take place most frequently when deter- 
mining, say, volatile matter in coal or in other materials. I think 
it has something to do with the formation of carbides. 



A paper presented at the Forty-third 
General Meeting of the American Elec- 
trochemical Society held in New York 
City, May 5, 1923, Dr. F. M. Becket in 
the Chair. 



SOME NOTES ON THE METALS OF THE PLATINUM GROUP.' 

By Fred E. Carter.^ 

Abstract. 
Some general remarks on metals of the group are given, par- 
ticular mention being made of the liability to gas absorption and 
of the consequent difficulties of melting. Results are given to 
show^ that the addition of iridium to platinum raises considerably 
the temperature required for annealing. Some alloys of the 
platinum metals among themselves are discussed, particularly 
those of platinum and iridium. 



When the comparative rarity of the platinum metals is taken 
into consideration, it is quite remarkable that so much attention 
has been given to them ; this statement applies, however, more 
accurately to the chemical rather than to the physical side, because, 
although large numbers of complex salts, etc., of the platinum 
metals have been prepared and investigated, the physical prop- 
erties of the metals of the group and their alloys have not been 
nearly so exhaustively examined. The average analyst has felt 
that there is something uncanny about the platinum metals ; he has 
found that it is practically impossible to get complete quantitative 
separation by a simple laboratory operation and that to make 
such separations complete precipitations, etc., must be carried out 
many times in succession. He ordinarily considers, for example, 
platinum ammonium chloride as an insoluble salt, particularly in 
the presence of alcohol, yet actually there are many salts which 
may be present in the solution, and in which the precipitated salt 
may be appreciably soluble. The author prefers therefore to 

^ Manuscript received February 9, 1923. 
= Baker and Co., Inc., Newark, X. J. 

397 



398 FRED E. CARTER. 

avoid in this paper the chemistry of the platinum metals, and to 
write down some facts on the subject from the physical and 
metallurgical standpoint. 

It is necessary, first of all, to emphasize the fact that much 
that has been published on the physical properties of the platinum 
metals is quite erroneous, because the metals used in the tests 
have been by no means pure, although this difficulty is not at all 
peculiar to the group in question, but applies generally to data 
on the metallic elements and their alloys. The platinum metals 
further add to our troubles by their susceptibility to gases. It 
is not intended in this paper to present precise measurements of 
physical standards, but rather to give, as is indicated by the 
title, some random notes on the platinum metals and to point out 
certain facts which may be of general interest. 

The platinum group of metals is composed of platinum, iridium, 
osmium, palladium, rhodium, and ruthenium. They occur prac- 
tically always in the elemental state, so that their metallurgy is 
comparatively simple and need not be discussed here. AH the 
platinum metals are white in color; most writers differentiate 
between their appearance, platinum being called tin-white, 
rhodium aluminum-white, osmium bluish, etc., but actually it is 
difficult to distinguish the group members by appearance only. 
The author would hesitate to say that there is any difference in 
color between platinum, palladium, and rhodium ; iridium might 
be conceded a more brilliant white appearance and ruthenium is 
whiter still ; osmium certainly has a bluish tinge. Such differences 
as are noted here might easily be due to surface oxide films or to 
variable crystal grain sizes, rather than to inherent different 
shades of color. 

The metals do not oxidize at ordinary temperatures, but on 
heating, certain of the group oxidize and volatilize. Table I, 
based on the contradictory literature on the subject, shows what 
probably happens when a hypothetical mixture of all the metals 
is gradually heated up. 

One of the most interesting general properties of the platinum 
group of metals is their capacity for dissolving gases, for therein 
probably lies the reason for their great activity as catalytic bodies. 
This property is extremely disagreeable to the manufacturer ; if 
the composition of the gas used for melting, say, platinum, is 



THE METALS OF THE PLATINUM GROUP. 399 

incorrect, gas may be dissolved by the molten metal and, since 
the solid metal is a much poorer solvent than the molten, set free 
on solidification, the metal then "spits" in the same manner as 
does solidifying silver which has been saturated with oxygen in 
the molten condition. Generally, however, the gas has not the 
opportunity to escape in this way, and is partly entrapped in the 

Table I. 

Results of Heating the Platinum Group Metals. 

100° C. OsOi begins to evolve (if the metal is very finely divided the 

vapor is observed at considerably lower temperature, but 

compact metal does not oxidize appreciably below a dull red 

heat). 

450° C. Pt oxidizes to black PtO (if metal is finely divided and oxygen 

is passed). 
500° C. PtO decomposes to give Pt and Pt02. 
550° C. Pt02 decomposes to Pt and 0=. 

600° C. Rh and Ru, if finely divided, oxidize to black Rh^O. and 
bluish RuOj. 
Pd begins to oxidize to PdO, giving blue and red colors. 
700° C. Pd oxidizes to PdO. 
800° C. Ir begins to oxidize to IrOj. 
900° C. PdO is decomposed to Pd and O. 
1,000° C. Ir begins to volatilize freely as oxide. 

RuOj partially decomposes to Ru and O2. If oxygen is passed, 

some RuO* is formed and evolved. 
Pd, Pt and Rh begin to volatilize appreciably in the order 
named, as metals. 
1 150° C. Rh.O. decomposes to Rh and O. 
1,550° C. Pd melts. 
1,755° C. Pt melts. 
1,950° C. Rh melts. 
2,350° C. Ir melts. 
2.450° C. Ru melts. 
2.500° C. Rh boils. 
2,520° C. Ru boils. 
2.540° C. Pd boils. 
2.550° C. Ir boils. 
2,700° C. Os meks. 
3.910° C. Pt boils. 

The temperatures given from 2350° C. upwards are questionable. 

bar as small gas inclusions. These often do not appear until the 
bar is rolled down to thin sheet and annealed, when the surface 
is found covered with numerous gas blisters. A bar that is much 
gassed swells badly on solidifying and is remelted forthwith, but 
the manufacturer's trouble chiefly comes when not so much gas is 
trapped that swelling occurs and only shows up in the finished bar 



400 FRED E. CARTER. 

as a few blisters scattered throughout the bar. It is hoped that 
x-ray examination may eventually be useful in showing gas 
bubbles in the interior of ingots, but the usefulness of this method 
of examination has not yet been proved in the case of platinum. 

Coal gas and oxygen or hydrogen and oxygen are generally 
used for melting the metals, and it is obvious that great care must 
be taken to have the correct proportions of gas or hydrogen and 
oxygen. Platinum must be melted in a distinctly oxidizing 
atmosphere, otherwise the blister trouble will appear; palladium, 
if melted by a reducing flame, is absolutely friable, the well- 
formed crystal grains being apparently without cohesion and easily 
separable by the fingers ; rhodium blisters if melted under oxidiz- 
ing conditions ; iridium behaves like platinum ; osmium and 
ruthenium rapidly volatilize in an oxidizing flame. It will be 
evident that difficulties arise when, say, alloys of platinum, 
iridium, and rhodium, or of platinum, palladium, and osmium 
have to be melted; in such cases experience has pointed out the 
special precautions that must be taken. 

The obvious method of overcoming such difficulties is to melt 
in vacuo and by electricity, but even then the troubles are not yet 
avoided, because refractories which are suitable for oxy-hydrogen 
gas melting may react with the molten metals under such condi- 
tions. Wichers^ has shown that platinum-calcium alloys are 
formed if platinum is melted in a lime crucible with a reducing 
atmosphere existing in the crucible. If such alloy formation is 
to be avoided excess oxygen in the oxy-hydrogen flame must be 
used. Also it was shown that if platinum is melted electrically in 
a magnesia crucible an alloy of platinum containing about three 
per cent magnesium may be produced. In parenthesis, it may be 
observed that such results force us to the conclusion that our 
ideas of stability of compounds must be modified when we get 
into the higher ranges of temperature. 

Of course, graphite would be the ideal crucible material to use 
for melting in vacuo, but unfortunately the platinum metals are 
readily attacked by carbon. It is not even necessary actually to 
melt the metal in carbon vapor for the platinum to be rendered 
quite dark in appearance, to be strongly modified in its micro- 
scopic structure, and to be made absolutely brittle. One way of 

» j. Am. Chem. Soc. 43, 1268 (1921), 



THU METALS OF THE PLATINUM GROUP. 401 

avoiding these troubles is to use the old "French method," which 
consists in pressing Pt sponge into a briquet and heating to about 
1,000° C. In this way the grey platinum mass is gradually 
"metallized," and can then be worked down to thin sheets in the 
usual way. The finer the state of division of the original plat- 
inum, the more readily does this metallizing take place. The 
process, however, lacks one advantage of the ordinary melting 
process, namely, the refining effect {i. e., removing the base metal) 
of the lime on the molten metal. 

Some indication has been given above of how the loss of the 
platinum metals by volatilization takes place, which loss is of 
course important in crucible ware ; it is necessary to decide what 
is the alloy which will lose least weight when heated to 1,000° or 
1,200° C. for several hours. Platinum-iridium alloys, high in 
iridium, lose in weight considerably at these temperatures, owing 
to volatilization of the iridium and must be avoided; platinum- 
rhodium is practically eliminated by the high cost of the rhodium, 
chemically pure platinum is good so far as constancy in weight 
is concerned, but is rather soft. The Bureau of Standards* has 
therefore recommended as a compromise that a small amount of 
platinum metals (chiefly iridium) other than platinum may be 
present, suggesting that the alloy used should not show more 
than 1 m. v. against chemically pure platinum at 1,100° C. ; this 
corresponds to about 0.3 per cent iridium. Crucibles, etc., made 
from such material are constant in weight and reasonably stiff. 

The metals of the group alloy with one another in all propor- 
tions, the alloys being solid 'solutions, as is usual in the case of 
combinations amongst the closely related elements of a group. 
There does not appear to be any case where the meUing point of 
the alloy is lower than either of the constituents (as, for example, 
occurs with gold and copper), but always the melting points of 
the alloys are intermediate between those of the constituent 
metals. Micro-photographs show that the addition of a second 
platinum metal to platinum itself causes a distinct refining of the 
crystal structure. For example, the crystal grains of a series of 
annealed iridio-platinum alloys show with increasing iridium a 
decreasing size of grain. Metallurgical examination also shows 

* Bureau of Standards, Sci. Paper 254. 



402 



FRED E. CARTER. 



that the alloys are homogeneous and, after adequate annealing, 
are practically free from any "coring" in the crystal grains. 

The temperature required to render platinum dead soft is 
comparatively low, but this temperature is considerably raised 
by the addition of even a small percentage of iridium. Fig. 1 
shows the large effect of traces of iridium on the annealing point 



120 

( 






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►—a 




















" 




-^ 


^ 
















lOO 
90 










\N" 


^ 




















\ 


\ 


\ 


















\ 




•\ 










80 










1 




\ 


















1 






\ , 








70 


































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^ 


CRUC. 




50 














S) 






^ 


















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k— Q— ^ 








;^ — A — 1 


40 
30 
20 






C.P. 




















































lO 














. 













zoo 300 400 30O •OO 700 800 900 lOOO 

TEMPERATURE. PESREES CEMTIGR.ADE 
Fig. 1. 



of platinum. The curve marked "C. P." is for platinum of a high 
degree of purity (temperature coefficient of resistance, 0.00391), 
and that marked "Cruc." is for platinum containing 0.1 per cent 
iridium (0.48 m. v. against C. P. Pt), such as is used for crucible 
ware, etc. The furnace, a platinum-wound electric tube furnace 
equipped with platinum-rhodium thermocouple, was slowly 
brought up to temperature, and the samples of metal, 1.9 x 1.3 x 
0.3 cm. (^ X ^ X ^8 i»-) ^vere introduced and kept in the fur- 



THE METALS OF THE PLATINUM GROUP. 403 

nace for 5 min. after they had reached the furnace temperature ; 
the hardness was tested in a Brinnell machine. 

It is necessary to make some further reference to Fig. 1. Rose' 
showed that traces of impurity raise the annealing temperature 
of gold appreciably ; hydrogen was found to be especially effec- 
tive in this respect, 0.002 per cent raising the temperature of 
annealing from 150° C. to over 300° C. Phelps*' confirmed Rose's 
results. It was believed by the present author that a similar effect 
had been shown for platinum, although the impurity is not neces- 
sarily hydrogen. However, another factor may have been influ- 
ential in the results here obtained. It is well known that an 
increase in the amount of cold work done on a metal previous to 
annealing causes a decrease in the temperature required to anneal, 
and it was thought possible that the two samples of platinum in 
Fig. 1 were not in exactly the same strained condition, in spite 
of the fact that both had been cold rolled from }i in. to ^ in. 
Another sample of platinum, not quite so pure (it gave 0.05 m. v. 
positive to the platinum previously used), was rolled in the same 
way, and tested, and it was found that the temperature required 
for annealing was practically as high as that necessary for the 
"crucible" platinum of the figure. The same sample was then re- 
melted and cold rolled from ^i in. to j4. in. instead of from ^/^ in. 
to % in. The annealing temperature now was even lower than 
that shown in the figure. There seems to be little doubt, there- 
fore, that in the case of almost pure platinum the previous history 
of the sample has more eflfect on the annealing temperature than 
has the purity. 

It will be seen from the figure that for pure platinum the 
required temperature is about 650° C, while for platinum with 
only 0.1 per cent iridium the temperature is about 1,000° C. 
Further additions of iridium do not raise the annealing point 
much. For example, platinum with ten per cent iridium requires 
1,150° C. to become fully annealed in five minutes; complete 
crystallization of the alloys containing 20 and 25 per cent iridium 
may be brought about at this same temperature, but require a 
considerably longer time. 

It is unnecessary here to do more than to draw attention to the 

"J. Inst, of Metals, 10, ISO (1913). 
"J. Inst, of Metals, 12. 125 (1914). 



404 FRED E. CARTER. 

slight increase in hardness of platinum on annealing at about 
300° C. This phenomenon of a slight hardening at tempera- 
tures just below that at which softening begins seems to be a 
general one in commercially pure metals and in alloys. It cer- 
tainly is quite pronounced in many gold alloys for which the 
author has drawn curves similar to Fig. 1. It is interesting, in 
view of some theories which have been advanced in explanation, 
to find this phenomenon occurring in the case of a metal of such 
extreme purity as the platinum used here. 

PHYSICAL CHARACTERISTICS OF EACH METAL. 

Platinum. Electrical resistance at 0° C. is 60.5 ohms per mil 
foot (10.06 microhms per cm. cube) for hard drawn platinum, 
and 59.8 ohms per mil foot (9.96 microhms per cm. cube) for 
the annealed material. The temperature coefftcient of resistance 
is 0.00392 or even slightly higher for the extremely pure metal.^ 

The melting point is 1,755° C.,^ apparently being the same for 
metal melted in air or in vacuo. The melting point is depressed 
by the presence of traces of carbon in the metal. 

The Brinnell hardness is about 110 in the hard worked and 47 
in the annealed condition. The Erichsen number for ductility 
of the annealed sheet 0.040 in. thick is 12,2 mm. 

Pt wire is drawn down commercially directly to 0.0007 in., 
while if drawn by the Wollaston method (that is, a platinum core 
and a covering tube of a metal, e. g., silver, which can be dissolved 
off later without attacking the platinum, are drawn down together) 
the diameter may be made one-tenth or even one-hundredth of 
this size. 

Iridium. The melting point is about 2,350° C.® and possibly 
higher. This metal is little used except in alloy form. It is gen- 
erally stated to be quite a hard metal, but actually such statements 
are made from tests with a very impure material. The chemically 
pure metal is fairly soft — about the same as 90 Pt 10 Ir. Brinnell 
hardness, 172 (cast). Iridium is insoluble in aqua regia. 

Osmium. The melting point is about 2,700° C, but this figure 
must be considered as only an approximation. It volatilizes 

" Bureau of Standards. 

' Bureau oi Standards, Circular 35. 

• Loc. fir. 



THE METALS OF THE PLATINUM GROUP. 405 

rapidly as osmium tetroxide if heated in air, and the melting 
should be done in vacuo; even in vacuo osmium on heating close 
to its melting point volatilizes in the form of a brown vapor. 
Osmium is insoluble in aqtia regia. 

Palladium. The melting point is 1,550°C. ;^ as ordinarily 
melted the metal retains considerable quantities of gas, as is 
shown by the fact that if it is remelted in vacuo there is a violent 
evolution of gas just at the melting point. The metal forms 
different oxides which are stable only within certain narrow limits 
of temperature. If an ingot of palladium is allowed to cool slowly 
it becomes coated with thin oxide films of red, green and blue. 
If it is desired to have a bright finish to a bar, it is only necessary 
to quench it, red-hot, in water. Brinnell hardness, 49 (Cast). 
Palladium is soluble in concentrated nitric acid and in aqua regia. 

Rhodium. This metal has been obtained in a high state of 
purity, since it is used for making the 10 per cent alloy with 
platinum, as the positive element in precious metal thermo- 
couples; if the metal is even slightly impure the curve for the 
electromotive force against platinum at once shows discrepancies. 

The melting point is 1,950° C," if melted in air the metal is 
coated with a blue oxide film, but in vacuo the metal is perfectly 
white. Brinnell hardness, 139 (Cast). Rhodium is insoluble in 
aqua regia. 

Rtithetiium. The melting point is about 2,450° C.,* but it is 
not at all certain that the metal has ever been obtained in the chem- 
ically pure state. Melted in air it is coated with a blue-black 
oxide; melted in vacuo it remains quite bright, although a black 
deposit settles in cooler parts of the apparatus. Brinnell hardness, 
220 (Cast), but the pure metal would certainly be considerably 
softer than this. Ruthenium is insoluble in aqua regia. 

ALLOYS. 

The metals of the platinum group form many useful alloys with 
other metals outside the group, of which may be cited palladium- 
gold alloys for laboratory ware, etc., palladium-silver for contacts, 
platinum-copper alloys of remarkably high electrical resistance, 
etc. Discussion of these would lead too far afield, and in this 
paper mention will be made only of the alloys formed among the 
platinum metals themselves. 



406 FRED E. CARTER. 

Platinum-iridium alloys undoubtedly constitute the most im- 
portant series. "Crucible platinum" is platinum with a small 
quantity of iridium in it (less than 0.3 per cent.) This iridium is 
sufficient to stiffen the pure metal slightly and probably helps to 
reduce the tendency to form large crystals. Ordinary commercial 
platinum is by no means pure platinum ; it contains from 1 to 3 
per cent, iridium, which, although double the value of platinum, is 
not worth while extracting, owing to the chemical difficulties 
involved ; also traces of all the other platinum metals are present, 
together with appreciable quantities of iron. Alloys useful to 
the jewelry world are platinum with 5 to 10 per cent iridium, 
known to the trade as "hard" platinum ; here again the iridium 
includes all the other platinum metals in small quantity. C. P. 
platinum with 10 per cent C. P. iridium would be much softer 
than the ordinary commercial "10 per cent." The 15 and 20 per 
cent iridium alloys are used for electrical contacts and for hypo- 
dermic needles, and indeed in many places where a hard precious 
metal alloy with reasonably good working properties is required. 
The 25 and 30 per cent iridium alloys are considerably harder and 
are rather difficult to work without special precautions. They are 
chiefly used for hypodermic needles. 

The approximate figures for Brinnell hardness of some typical 
commercial iridio-platinum alloys are shown in Table II. These 
alloys are widely used for resistance wires where a precious metal 
alloy is required. The approximate resistances of some of the 
commercial alloys are given in Table III. Alloys made from pure 
materials have resistances as shown in Table IV. 

The addition of iridium to platinum decreases the rate at which 
the latter dissolves in aqua regia; platinum with 20 per cent 
iridium is very slowly dissolved, while the 25 and 30 per cent 
alloys are practically unattacked. 

Platinum-rhodium. The only important alloy of these metals is 
that containing 10 per cent rhodium, used at the present time for 
the positive element of the well-known Pt-PtRh thermocouple ; 
although the electromotive force developed by this couple is only 
about 60 per cent of that given by the corresponding Pt-Ptir 
couple, it is preferred on account of the low volatility of the 
rhodium compared with the iridium, and the consequent greater 
constancy of e. m. f. A great many industries require accurate 



THE METALS OF THE PLATINUM GROUP. 

Table II. 
Hardness of Commercial Iridio-Platinnm Alloys. 



407 



Composition 


Brinnell Hardness 


Pt 


Ir 


Hard 




per cent 


per cent 


Worked 


Annealed 


95 


5 


170 


110 


90 


10 


220 


150 


85 


15 


280 


190 


80 


20 


330 


230 


75 


25 


370 


270 


70 


30 


400 


310 



Table III. 
Resistances of Commercial Iridio-Platinnm Alloys. 



Composition 


Resistance 


Pt Ir 
per cent per cent 


Microhms 
per cm. cube 


Ohms 
per mil ft. 


95 
90 
85 
80 
75 


5 
10 

15 • 
20 
25 


20.0 
26.6 
30.8 
3U 
34.9 


120 
160 
185 
200 
210 



Table IV. 
Resistances of Pure Iridio-Platinnm Alloys. 



Composition 


Resistance 


Pt 


Ir 


Microhms 


Ohms 


per cent 


per cent 


per cm. cube 


per mil ft. 


99.9 


0.1 


11.0 


660 


99.8 


0.2 


n.3 


67.9 


99.0 


1.0 


12.4 


74.7 


98.0 


2.0 


15.0 


89.9 


96.0 


4.0 


17.3 


104 


94.0 


6.0 


19.5 


117 



4o8 FRED E. CARTER. 

temperature control at some stage of manufacture, and it is 
essential to have reliable thermocouples. Pt-PtRh certainly 
remains the most constant in e. m. f. and, with care in manu- 
facture, can be made to agree to the standard curve of Day and 
Sosman to v^^ithin a degree or two. Certain other alloys, with 
the rhodium somewhat above or below 10 per cent are used in 
thermocouples, but that containing exactly 10 per cent seems the 
most satisfactory. 

The 10 per cent rhodium alloy is much softer (Brinnell number, 
90 when annealed) than the corresponding iridium alloy and also 
has lower electrical resistance (110 ohms per mil ft.; 18.3 
microhms per cm. cube). 

PlafiniDJi-palladiinii alloys are used to some extent in jewelry; 
the addition of the palladium does not harden the platinum much, 
and the resulting alloys are readily workable. 

Platiniim-osmhim alloys have been made containing up to 30 per 
cent osmium ; they are extremely hard, the osmium having about 
two and one-half times the hardening effect of iridium.^" The 
osmium also increases the electrical resistance of platinum about 
two and one-half times as much as does the same amount of 
iridium. They are not used commercially, because annealing at 
even a dull red heat is sufficient to expel some of the osmium 
and thus alter the composition of the alloys. 

Indium-osmium alloys occur in the natural state as osmiridium ; 
the grains are extremely hard and are used as tips for fountain 
pens. The alloys are now being made artificially in any desired 
proportions and by suitable treatment crystal grains of the proper 
size for pens are obtained. 

Palladium-osmium alloys are easily workable, but cannot be 
heated without losing osmium. 

There are also several ternary and quaternary alloys finding 
commercial application which may be mentioned. Platinum- 
iridium-os)yiium alloys are used for sparking points ; platimtm- 
iridium-rhodium alloys are used for radio tubes ; plafinum-pal- 
ladium-osmium alloys were formerly used in jewelry, but the 
partial volatilization of the osmium as tetroxide was disagreeable 
and platinum-palladium-rhodium alloys are now preferred. 

"Johnson, V,. P. 29/23 0910); Heraeus. C. P. 239,704 (1913): Zinimermann, U. S. 
P. 1,055,199 (1913). 



INDEX 



PAGE 

Acheson, Dr. Edward G., and His Work — F. A. J. FitzGerald S 

Air Electrode, Electrotitration with the Aid of the — N. Howell Furman 79 

Alkaline Solutions, The Hydrogen Electrode in— A. H. W. Aten 89 

Alloy for Thermocouples, The Preparation of Platinum and of Plati- 
num-Rhodium — Robert P. Neville 371 

Alloying Elements in Steel, Inherent Effect of — B. D. Saklatwalla 271 

American Electrochemist Abroad, Opportunities for the — C. G. Schlue- 

derberg 21 

Annual Report of the Board of Directors 12 

Annual Report, Secretary's 13 

Annual Report, Treasurer's 17 

Arcs, Carbon, The Relation Between Current, Voltage and the Length 

of— A. E. R. Westman 171 

Arsem, W. C. — Discussion 166 ct seq., 229, 313 

Artificial Magnetite, Oxygen Overvoltage of, in Chlorate Solutions — 

H. C. Howard 51 

Aten, A. H. W. — Discussion 77 et seq. 

Aten, A. H. W. — The Hydrogen Electrode in Alkaline Solutions 89 

Base Metal, The Influence of, on the Structure of Electrodeposits — 

W. Blum and H. S. Rawdon See Vol. 44 

Baughman, Will — Discussion 313 et seq. 

Baughman, Will — Notes on the Metallurgy of Lead Vanadates 281 

Becket, F. M..— Discussion 268 et seq. 

Becket, F. M. — Some Effects of Zirconium in Steel 261 

Benjamin, E. O. — Discussion 75 ct seq., 349 

Benzene, Electrolytic and Chemical Chlorination of — Alexander Lowy 

and Henry S. Frank 107 

Blum, W. and H. E. Haring — Current Distribution and Throwing 

Power in Electrodeposition See Vol. 44 

Blum, W. and H. S. Rawdon— The Influence of the Base Metal on the 

Structure of Electrodeposits See Vol. 44 

Board of Directors, Annual Report of the 12 

Boron, Uranium, Titanium, Cerium and Molybdenum in Steel, Experi- 
ments with— H. W. Gillett and E. L. Mack 231 

Brooke, Frank W.— Methods of Handling Materials in the Electric 

Furnace and the Best Type of Furnace to Use 149 

Caplan, P. — Discussion 75 

Caplan, P., M. Knobel and M. Eiseman— The Effect of Current Density 

on Overvoltage 55 

I 409 

27 



410 INDEX. 

PAGE 

Carbon Arcs, The Relation Between Current, Voltage and the Length 

of— A. E. R. Westman 171 

Carter, F. K.— Discussion 383, 395 

Carter, Fred E. — Some Notes on the Metals of the Platinum Group.. 397 
Cerium, Uranium, Boron. Titanium and Molybdenum in Steel, Experi- 
ments with— H. W. Gillett and E. L. Mack 231 

Chemical, and Electrolytic, Chlorination of Benzene — Alexander Lowy 

and Henry S. Frank 107 

Chlorate Solutions, Oxygen Overvoltage of Artificial Magnetite in — 

H. C. Howard 51 

Chlorides, The Reduction of Some Rarer Metal, by Sodium — M. A. 

Hunter and A. Jones See Vol. 44 

Chlorination of Benzene, Electrolytic and Chemical — Alexander Lowy 

and Henry S. Frank 107 

Chromizing— F. C. Kelley 351 

Cobalt — Its Production and Uses — C. W. Drury 341 

Cone, E. F. — Discussio>i 268 

Conversion of Diamonds to Graphite at High Temperatures, The — 

M. deKay Thompson and Per K. Frolich 161 

Cooper, H. S. — Discussion 227 et sea. 

Cooper, Hugh S. — The Preparation of Fused Zirconium 215 

Crosby, E. L. — Discussion 200 

Cunningham, Thos. R., and Jas. A. Holladay — Experiments Relative 

to the Determination of Uranium bj' Means of Cupferron 329 

Cupferron, Experiments Relative to the Determination of Uranium by 

Means of — Jas. A. Holladay and Thos. R. Cunningham 329 

Current Densitj', The Effect of, on Overvoltage — M. Knobel. P. Caplan 

and M. Eiseman 55 

Current Distribution and Throwing Power in Electrodeposition — H. E. 

Haring and W. Blum See Vol. 44 

Current, Voltage and the Length of Carbon Arcs, The Relation Be- 
tween — A. E. R. Westman 171 

Dawson, F. G. — Discussion — 186 

Detinning, Electric Furnace, and Production of Synthetic Gray Iron 

from Tin-Plate Scrap — C. E. Williams, C. E. Sims and C. A. 

Newhall 191 

Diamonds, the Conversion of, to Graphite at High Temperatures 

M. deKay Thompson and Per K. Frolich 161 

Doremus, Chas. A. — Discussiion 323 

Drury, C. W. — Cobalt — Its Production and Uses 341 

Drury, C. \Y.— Discussion 350 

Edward G. Acheson and His Work— F. A. J. FitzGerald 5 

Effect of Current Density on Overvoltage. The — M. Knobel, P. Caplan 

and M. Eisiman 55 



INDEX. 4H 

PAGE 
Effect of Iron on the Electrodeposition of Nickel, The — M. R. Thomp- 
son See Vol. 44 

Eiseman, M., M. Knobel, and P. Caplan— The Effect of Current Density 

on Overvoltage 55 

Electrically Heated Apparatus, Heat Insulating Materials for — J. C. 

Woodson 127 

Electric Furnace Detinning and Production of Synthetic Gray Iron 
from Tin-Plate Scrap — C. E. Williams, C. E. Sims and C. A. 

Newhall 191 

Electric Furnace, Methods of Handling Materials in the, and the Best 

Type of Furnace to Use — Frank W. Brooke 149 

Electrochemist Abroad, Opportunities for the American — C. G. Schlue- 

derberg 21 

Electrode, Air, Electrotitration with the Aid of the — N. Howell Furman 79 

Electrode, Hydrogen, in Alkaline Solutions — A. H. W. Aten 89 

Electrodeposition", Current Distribution and Throwing Power in — H. E. 

Haring and W. Blum See Vol. 44 

Electrodeposition of Iron, Notes on the — Harris D. Hineline 119 

Electrodeposition of Nickel on Zinc, The — A. Kenneth Graham, 

See Vol. 44 
Electrodeposition of Nickel, The Effect of Iron on the — M. R. Thomp- 
son See Vol. 44 

Electrodeposits, The Influence of the Base Metal on the Structure of — 

W. Blum and H. S. Rawdon See Vol. 44 

Electrolytic and Chemical Chlorination of Benzene — Alexander Lowy 

and Henry S. Frank 107 

Electrotitration with the Aid of the Air Electrode — N. Howell Furman 79 
Experiments Relative to the Determination of Uranium by Means of 

Cupferron — Jas. A. Holladay and Thos. R. Cunningham 329 

Experiments with Uranium, Boron, Titanium, Cerium and Molybde- 
num in Steel— H. W. Gillett and E. L. Mack 231 

Fink, Colin G.— Discussion 53, 167 ct seq.. 312, 349, 368 

FitzGerald, F. A. J. —Discussion 147, 168 

FitzGerald, F. A. J.— Dr. Edward G. Acheson and His Work 5 

Forty-third General Meeting, Proceedings of 1 

Frank, Henry S., and Alexander Lowy — Electrolytic and Chemical 

Chlorination of Benzene 107 

Frolich, Per K., and M. DeKay Thompson — The Conversion of Dia- 
monds to Graphite at High Temperatures 161 

Furman, N. H. — Discussion 87 

Furman, N. Howell — Electrotitration with the Aid of the Air Electrode 79 

Fused Zirconium, The Preparation of — Hugh S. Cooper 215 

General Meeting, Forty -third, Proceedings of 1 

Gillett, H. W., and E. L. Mack — Experiments with Uranium, Boron, Ti- 
tanium, Cerium and Molybdenum in Steel 231 



412 INDEX. 

PAGE 

Gillett, H. W.— Discussion 201 et seq., 258, 268 et sea. 

Graham, A. Kenneth — The Electrodeposition of Nickel on Zinc. 

See Vol. 44 
Graphite. The Conversion of Diamonds to, at High Temperatures — M. 

DeKay Thompson and Per K. Frolich 161 

Gray Iron, Synthetic, from Tin-PIate Scrap, Electric Furnace Detin- 
ning and Production of — C. E. Williams, C. E. Sims and C. A. 

Newhall 191 

Guests and Members Registered at the Forty-third General Meeting... 18 

Guiterman, Kenneth S. — Discussion 347 et seq. 

Handling Materials in the Electric Furnace. Methods of. and the Best 

Type of Furnace to Use — Frank W. Brooke 149 

Haring, H. E. and W. Blum — Current Distribution and Throwing 

Power in Electrodeposition See Vol. 44 

Hart, L. O. — Discussion 368 et seq. 

Heat Insulating Materials for Electrically Heated Apparatus — J. C. 

Woodson 127 

Hering, Carl — Discussion 77, 146 

Hineline, Harris D. — Notes on the Electrodeposition of Iron 119 

Holladay, Jas. A. and Thos. R. Cunningham — Experiments Relative to 

the Determination of Uranium by Means of Cupferron 329 

Horsch, W. G.— Discussion 54, 75, 88 

Howard, H. C. — Discussion 50, 54 

Howard, H. C. — Oxygen Overvoltage of Artificial Magnetite in Chlo- 
rate Solutions 51 

Hunter, M. A. and A. Jones — The Reduction of Some Rarer Metal 

Chlorides by Sodium See Vol. 44 

Hydrogen Electrode in Alkaline Solutions, The— A. H. W. Aten 89 

Influence of the Base Metal on the Structure of Electrodeposits, The — 

W. Blum and H. S. Rawdon See Vol. 44 

Inherent Effect of Alloying Elements in Steel — B. D. Saklatwalla 271 

Insulating Materials, Heat, for Electrically Heated Apparatus — J. C. 

Woodson 127 

Investigations on Platinum Metals at the Bureau of Standards — Ed- 
ward Wichers and Louis Jordan 385 

Ionization Problems, Newer Aspects of — Hugh S. Taylor 31 

Iron, Notes on the Electrodeposition of — Harris D. Hineline 119 

Iron, Synthetic Gray, from Tin-Plate Scrap, Electric Furnace Detin- 
ning and Production of — C. E. Williams, C. E. Sims, and C. A. 

Newhall 191 

Iron, The Effect of, on the Electrodeposition of Nickel — M. R. Thomp- 
son See Vol. 44 

James, C. — Present Status of the Production of Rarer Metals 203 

Johnston, John — Discus^non 48 



INDEX. 413 

PAGE 

Jones, A. and M. A. Hunter — The Reduction of Some Rarer Metal 

Chlorides by Sodium See Vol. 44 

Jordan, Louis and Edward Wichers — Investigations on Platinum 

Metals at the Bureau of Standards 385 

Jordan, Louis — Discussion 384 

Kelleher, J. — Discussion 188 

Kelley, F. C— Chromizing 351 

Kelley, F. C. — Discussion 370 

Knobel, M. — Discussion 54, 75, 77 et seq., 104 et seq. 

Knobel, M., P. Caplan, and M. Eiseman — The Effect of Current Den- 
sity on Over voltage 55 

Knobel, M. — The Reactions of the Lead Storage Battery 99 

Lead Storage Battery, The Reactions of the — M. Knobel 99 

Lead Vanadates, Notes on the Metallurgy of — Will Baughman 281 

Lind, S. C. — Discussion AS et seq.. 168 et seq. 

Lowy, Alexander and Henry S. Frank — Electrolytic and Chemical 

Chlorination of Benzine 107 

Mack, E. L. and H. W. Gillett — Experiments v/iih Uranium, Boron, Ti- 
tanium, Cerium and Molybdenum in Steel 231 

Magnetite, Artificial, Oxygen Overvoltage of, in Chlorate Solutions — 

H. C. Howard . . .' 51 

Marden, J. W., and H. C. Rentschler — Discussion 323 ef seq. 

Marden, J. W. — Discussion 225 et seq. 

Members and Guests Registered at the Forty-third General Meeting... 18 
Metal Chlorides, The Reduction of Some Rarer, by Sodium — M. A. 

Hunter and A. Jones See Vol. 44 

Metallic Uranium, Preparation of — R. W. Moore 317 

Metallurgy of Lead Vanadates, Notes on the — Will Baughman 281 

Metals of the Platinum Group, Some Notes on the — Fred E. Carter... 397 

Metals, Rarer, Present Status of the Production of — C. James 203 

Methods of Handling Materials in the Electric Furnace and the Best 

Type of Furnace to Use — Frank W. Brooke 149 

Molybdenum, Uranium, Boron, Titanium, and Cerium in Steel, Experi- 
ments with— H. W. Gillett and E. L. Mack 231 

Moore, R. B. — Discussion 350 

Moore, R. W. — Discussion 326 et seq. 

Moore, R. W. — Preparation of Metallic Uranium 317 

Moore, W. C. — Discussion 49 

Neville, Robert P. — The Preparation of Platinum and of Platinum- 
Rhodium Alloy for Thermocouples 371 

Newer Aspects of Ionization Problem.s — Hugh S. Taylor 31 

Newhall, C. A., C. E. Sims, and C. E. Williams — Electric Furnace De- 
tinning and Production of Synthetic Gray Iron from Tin-Phte 
Scrap 191 



414 INDKX. 

PAGE 
Nickel, The Effect of Iron on the Electrodeposition of — M. R. Thomp- 
son See Vol. 44 

Nickel, The Electrodeposition of, on Zinc — A. Kenneth Graham, 

See Vol. 44 

Notes on the Electrodeposition of Iron — Harris D. Hineline 119 

Notes on the Metallurgy of Lead Vanadates — Will Baughman 281 

Opportunities for the American Electrochemist Abroad — C. G. Schlue- 

derberg 21 

Overvoltage, Oxygen, of Artificial Magnetite in Chlorate Solutions — 

H. C. Howard 51 

Overvoltage, The Effect of Current Density on — M. Knobel, P. Caplan, 

and M. Eiseman 55 

Oxygen Overvoltage of Artificial Magnetite in Chlorate Solutions — - 

H. C. Howard 51 

Platinum Group, Some Notes on the Metals of the — Fred E. Carter. .. .397 
Platinum Metals at the Bureau of Standards, Investigations on — Ed- 
ward Wichers and Louis Jordan 385 

Platinum, The Preparation of, and of Platinum-Rhodium Alloy for 

Thermocouples — Robert P. Neville 371 

Preparation of Fused Zirconium, The — Hugh S. Cooper 215 

Preparation of Metallic Uranium — R. W. Moore 317 

Preparation of Platinum and of Platinum-Rhodium Alloy for Thermo- 
couples. The— Robert P. Neville 371 

Present Status of the Production of Rarer Metals — C. James 203 

Proceedings of the Forty-third General Meeting 1 

Ralston, O. C. — Discussion 87, 349 et seq. 

Rarer Metal Chlorides, The Reduction of Some, by Sodium — M. A. 

Hunter and A. Jones See Vol. 44 

Rarer Metals, Present Status of the Production of — C. James 203 

Rawdon, H. S. and W. Blum — The Influence of the Base Metal on the 

Structure of Electrodeposits See Vol. 44 

Reactions of the Lead Storage Battery, The — M. Knobel 99 

Reduction of Some Rarer Metal Chlorides by Sodium, The — M. A. 

Hunter and A. Jones See Vol. 44 

Reeve, H. T. — Discussion 383 

Relation Between Current, Voltage and the Length of Carbon Arcs, 

The— A. E. R. Westman 171 

Rentschler, H. C. and J. W. Marden — Discussion 323 et scq. 

Report, Annual, of the Board of Directors 12 

Report, Annual, Secretary's ■ 13 

Report, Annual, Treasurer's 17 

Report of Tellers of Election 4 

Rhodium-Platinum Alloy for Thermocouples. The Preparation of 

Platinum and of — Roliert P. Neville 371 

Richardson, H. K. — Discussion 369, 382 



INDEX. 



415 



_ , , „ PAGE 

baklatwalla, B. D.— Discussion 312 

Saklatwalla, B. D.— Inherent Effect of Alloying Elements in Steel 271 

Schluederberg, C. G.— Discussion 200 

Schluederberg, C. G.— Opportunities for the American Electrochcmist 

Abroad 21 

Scrap, Tin-Plate, Electric Furnace Detinning and Production of Syn- 
thetic Gray Iron from— C. E. Williams, C. E. Sims and C.A. 

Newhall jni 

Secretary's Annual Report J3 

Sims, C. E., C. E. Williams and C. A. Xewhall— Electric Furnace De- 
tinning and Production of Synthetic Gray Iron from Tin-Platc 

Scrap 291 

Sodium, The Reduction of Some Rarer Metal Chlorides by— M. A. 

Hunter and A. Jones ' See Vol. 44 

Some Eflfects of Zirconium in Steel — F. M. Becket 261 

Some Notes on the Metals of the Platinum Group— Fred E. Carter. .. .397 
Steel, Experiments with Uranium, Boron, Titanium, Cerium and Mo- 
lybdenum in— H. W. Gillett and E. L. Mack 231 

Steel, Inherent Effect of Alloying Elements in— B. D. Saklatwalla 271 

Steel, Some Effects of Zirconium in — F. M. Becket 261 

St. John, Ancel — Discussion jgp 

Storage Battery, Lead, The Reactions of the— M. Knobel 99 

Stoughton,, Bradley — Discussion 258 

Synthetic Gray Iron from Tin-Plate Scrap, Electric Furnace Detin- 
ning and Production of— C. E. Williams, C. E. Sims and C. A. 

Newhall joj 

Taylor, H. S. — Discuss-wn A9 et sea 

Taylor, Hugh S.— Newer Aspects of Ionization Problems '. 31 

Tellers of Election, Report of 4 

Tin-Plate Scrap, Electric Furnace Detinning and Production of Syn- 
thetic Gray Iron from— C. E. Williams, C. E. Sims and C. A. 

Newhall jgj 

Titanium, Uranium, Boron. Cerium and Molybdenum in Steel, Experi- 
ments with— H. W. Gillett and E. L. Mack .' 231 

Thermocouples, The Preparation of Platinum and of Platinum-Rho- 
dium Alloy for— Robert P. Neville 37I 

Thompson. M. DeKay and Per K. Frolich— The Conversion of Dia- 
monds to Graphite at High Temperatures 161 

Thompson, M. R.— Discussion 86 ^-^ seq. 

Thompson, M. R.— The Effect of Iron on the Electrodeposition of 

Nickel See Vol. 44 

Throwing Power, and Current Distribution, in Electrodeposition— 

H. E. Haring and W. Blum See Vol. 44 

Treasurer's Annual Report \y 



4i6 INDEX. 

PAGE 

Uranium, Boron, Titanium, Cerium and Molybdenum in Steel, Experi- 
ments with— H. W. Gillett and E. L. Mack 231 

Uranium, Experiments Relative to the Determination of, by Means of 

Cupferron — Jas. A. Holladay and Thos. R. Cunningham 329 

Uranium, Metallic, Preparation of — R. W. Moore 317 

Vanadates, Lead, Notes on the Metallurgy of — Will Baughman 281 

Voltage, Current, and the Length of Carbon Arcs, The Relation Be- 
tween — A. E. R. Westman 171 

Weir, Helen — Discussion 104 et scq. 

Westman, A. E. R. — Discussion 187 et seq. 

Westman, A. E. R. — The Relation Between Current, Voltage and the 

Length of Carbon Arcs 171 

Wichers, Edward and Louis Jordan — Investigations on Platinum 

Metals at the Bureau of Standards 385 

Williams, C. E., C. E. Sims and C. A. Newhall — Electric Furnace De- 
tinning and Production of Synthetic Gray Iron from Tin-Plate 
Scrap 191 

Williams, C. E. — Discussion .201 et scq. 

Woodson, J. C. — Discussion 147 

Woodson, J. C. — Heat Insulating Materials for Electrically Heated Ap- 
paratus 127 

Zinc, The Electrodeposition of Nickel on — A. Kenneth Graham, 

See Vol. 44 

Zirconium, Fused, The Preparation of — Hugh S. Cooper 215 

Zirconium in Steel, Some Effects of — F. M. Becket 261 



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