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East Engiii,
Library.
TS
6 90
• ^6-3. 3
\
ill
THE
Manufacture of Metallic Articles
Electrolytically. — Electro-
Engraving
BY
DR. ¥ PFANHAUSER
Manufacturer of Machinery, Apparatus and Chemical Prepar-
ations for Electroplating and Galvanoplastics
Authorized English Translation
BY
JOSEPH W. RICHARDS, M.A, A.C, Ph.D.
Professor of Metallurgy, Lehigh University ; Past President of
the American Electrochemical Society
EASTON, PA.
THE CHEMICAL PUBUSHING CO.
1906
1
,
Copyright, 1906, By The Chemical Publishing Co.
I
\
MONOGRAPHS
ON
Applied Electrochemistry
EDITED BY
VIKTOR ENGELHARDT.
Head Engineer and Chief Chemist of the Siemens & Halske A. G.,
Vienna.
WITH THE COOPERATION OF
Dr. E. Abel, Chemist for the Siemens & Halske A. G., Vienna.
E. G. Acheson, President of the International Acheson Graphite Co.,
Niagara Falls, N. Y.
Dr. P. Askenasy, Superintendent of the Akkumulatorwerke, Liesing.
H. Becker, Publisher of '* ly 'Industrie ^lectro-chimique," Paris.
Dr. W. Borchers, Professor at the Technical High School, Aachen.
Sh. Cowper-Coles, Publisher of "The Electrochemist and Metallur-
gist," London.
Dr. F. Dieffenbach, Professor at the Technical High School, Darm-
stadt.
Dr. G. Erlwein, Chief Chemist of the Siemens & Halske A. G., Berlin.
H. Friberg, Engineer of the Siemens & Halske, A. G., Berlin.
H. Gall, Director of the Soci^t^ d 'Electrochimie, Paris.
F. E. Giinther, Mining Engineer, Aachen.
Dr. F. Haber, Professor at the Technical High School, Karlsruhe.
Dr. C. Haussermann, Professor at the Technical High School, Stutt-
gart.
Dr. R. Hammerschmidt, Electrochemist, Charlottenburg.
Dr. G. Hausdorff, Registeed Chemist, Essen.
Dr. K. Kellner, General Drirector, Vienna.
A. Krakau, Professor of theElectrochemical Institute, St. Petersburg.
Dr. H. Landolt, Director of the Society for Electrochemical Industry,
Turgi.
Dr. M. Le Blanc, Professor at the Technical High School, Karlsruhe.
C. Liebenow, Engineer, Berlin.
Dr. R. Lorenz, Professor at the Swiss Polytechnic, Ziirich.
Dr. R. lyucion. Director of Solvay & Co., Briissels.
A. Minet, Publisher of ** ly'ifelectrochimie, " Paris.
A. Nettel, Engineer, Berlin.
H. Nissenson, Director of Akt.-Ges. of Stolberg & Westfalen,
Stolberg.
Dr. F. Peters, Instructor at the Royal Mining Academy, Berlin.
Dr. W. Pfanhauser, Manufacturer, Vienna.
Registered Chemist Dr. O. Prelinger, Chemist of the Siemens &
Halske A. G., Vienna.
Titus Ulke, M. E., Electrometallurgical and Mining Engineer of the
Lake Superior Power Co., Sault Ste. Marie, Ontario.
Dr. Th. Zettel, Chief Chemist of Brown-Boveri & Co,, Baden.
And other experts.
C.-4
CONTENTS
PAGB
I. HisTORiCAi, Review i
A. Introduction *. i
B. Advances in the Art i
II. Baths FOR Copper GAI.VANOPLASTY 3
A. Neutral Bath 3
B. Work of Chassy 3
C. Foerster*s Work on Quantitive Precipitation of Copper 4
D. Studies by Hiibl, 1886 6
III. Physicai, Properties of the Copper Deposit 14
A. Hiibrs Investigations 15
IV. Behavior of Copper Anodes 25
V. Constants of the Bath and Cai,cui,ation o^ the Amount
OF Deposit 28
VI. InDUSTRIAI. PI.ANTS .32
VII. Particui^ar Devices for Speciai, Purposes. Production
OF Uniform Deposits 37
A. Process of Bauer 39
B. Process of Anderson 39
C. Wurttemberg Process 40
D. Dumoulin Process 42
E. Method of the French Copper Company 43
F. Devices for Loosening of the Precipitates 43
G. Process of Sutherland 43
H. Process of Reinfeld 44
I. Method of Holl 44
J. Elmore's Process 45
K. Nussbaum's Process 46
Iv. Collapsible Forms 46
M. Elmore's Process 47
N. Collapsible Moulds of Gerhardi & Co 49
VIII. Manufacture of Metai^lic Powders and the Like 52
A. Process of the Societe Civile 54
B. Process of Hoepner 55
C. Process of Hiiber & Sachs 60
IX. Manufacture of Metai,i,ic Foii, 61
A. Process of Reinfeld 61
B. Process of Endruweit 61
C. Elmore's Process 63
vni CONTENTS
D. Desolle's Process 63
E. Process of Cowper-Coles 64
F. Process of Landauer & Co 64
. G. Process of Brandt & Nawrocki 69
H. Process of Endruweit 70
I. Process of Schroeder 70
J. Sheet Gold by Swan's Process 7a
K. Production of Plane Surfaces, Rieder*s Process 72
L. Elmore's^Process 75
X. Production of Wire, &c. 76
A. Process of Elkington 76
B. Fox's Process 76
C. Acheson's Process 76
D. Tavernier's Process 77
E. Process of Swan 78
F. Process of Sanders 84
G. Process of Forsythe and Fletcher 91
H. Process of Cowper-Coles 91
XI. Manufacture OF Bodies of Large Size 93
A. Process of J. Klein 93
B. Nussbaum's Process 100
C. Sutherland's Process 105
D. Elmore's Process 105
E. Process of Davis & Evans 106
F. Process of A. Krueger 106
XII. Manufacture of Parabouc Mirrors 108
A. Process of the Elmore German and Austro-Hungarian Metal
Company, Limited, "and P. E. Preschlin 108
B. Process of Cowper-Coles 108
XIII. Manufacture OF Tubes 117
A. Process of the French Copper Society 123
B. Process of Dumoulin 125
XIV. Ei^ECTROLYTic Etching '. 130
A. Burdette's Process 131
B. Hall & Thornton Process 133
XV. Ei.ECTROi,YTic Engraving 138
A. Introduction 138
B. Engraving with Partial Covering 139
C. Electro- Engraving Processes 140
D. Rieder's First Investigations 141
Appendix 149
PREFACE
While giving in the present small treatise a compilation of the
published information in the field of the manufacture of metallic
articles by electrolytic methods, I must say that it is impossible to
treat such an extensive field in so small a space in such a manner
that the technician, seeking for minute details, would not be com-
pelled to seek further information in special publications.
The material can only be handled in the form of abstracts, but
in many cases the incompleteness of the work is entirely due to
the fact that it has been impossible to publish all the secrets of the
trade. On these grounds I must unfortunately restrain myself in
many cases from presenting such important data as to the profit-
ableness of most of the processes ; yet in many cases I have at-
tempted to supply the lack of such data by my own calculations,
where the firms using the processes were unwilling to furnish
such data. In many cases profitableness of the processes may be
deduced from the data concerning the process, which have been
given.
Many of the processes meet with a great many unforseen diffi-
culties, such as in the details of apparatus or of technical practi-
cability ; many on the contrary cost more than the old processes.
The thoughtful artisan, however, will find much food for re-
flection in many of the processes described, and be induced to ex-
periment further in one or another direction, or to attempt to per-
fect some of these processes, and I will consider my task suffi-
ciently completed if I have furnished the impulse to this work by
mv modest efforts.
Vienna. W. P^anhaus^r.
I. HISTORICAL REVIEW.
INTRODUCTION.
M. H. Jakobi is generally acknowledged as the founder of gal-
vanoplastic reproduction and the industrial development of cop-
per precipitation resulting therefrom. He first presented the re-
sults of his pioneer work to the St. Petersburg Academy of Sci-
ences in 1838. However, Jordan and Spencer contested the
priority, but it has been proven that these brought their experi-
ments to a practical stage later than Jakobi. Jakobi also, like all
workers in galvanoplasty up until the last thirty years, worked
with the well-known cell apparatus, which in principle was prac-
tically a short-circuited Daniell cell.
In the year 1840 Murray introduced the graphitizing of non-
conducting surfaces and in 1842 reproduced the first engraved
copper plates by galvanoplastic methods.
ADVANCES IN THE ART.
The manufacture of useful articles in the electrolytic way could
naturally only become practicable with the advent of the modern
dynamo machine which thus makes available large quantities of
electrical energy. With the increased interest in all such pro-
cesses which used electricity there was a great increase along ex-
perimental lines, towards the bringing of electricity to the service
of the metal worker, and thus the circle of application rapidly
widened.
As in almost all branches of electrochemistry, so here, detailed
information of processes, such as is used by technicians for their
exact reproduction, are seldom to be had, and I must, in many
cases, limit myself to assumptions, especially where calculations
are involved.
At the present time there are a large number of more or less
technically available processes, widely divergent electrolytically,
for the manufacture of useful articles, in which in general copper
is used as the depositing metal ; and it is only very recently that
2 MANUFACTURE 01^ METALLIC OBJECTS
nickel has become of importance, unfortunately only to a limited
extent, because in the case of nickel quite serious difficulties are
encountered which limit the availability of this otherwise so suit-
able metal.
It can be said of some of the processes already developed that
they are competing successively with the older mechanical ones
and many of them will drive out the older processes as soon as the
small difficulties which stand in the way of their technical applica-
tion have been overcome by the general advance of the art.
Nevertheless, electrolysis has open before it a large and profita-
ble field in galvano-technics, when cheap power and raw mate-
rials are brought into combination with well organized processes
run on a large scale.
n. BATHS FOR COPPER GALVANOPLASTY.
The most important galvanic bath technically is the copper
bath. As the oldest and therefore the best known bath it has been
the most thoroughly investigated, and for this reason copper has
played the main role in the manufacture of articles electrolyti-
cally.
NEUTEAE BATH.
It has been found that when electrolyzing a neutral solution of
copper sulphate, CuSO^, (obtained by boiling it with copper car-
bonate, CuCOg, and subsequent filtration) there always results
brittle copper, which, in being lifted off the cathode, falls in
pieces. After continued use of the bath, particularly when em-
ploying high current densities, the character of the precipitate im-
proves so that finally perfectly flexible homogeneous metal is ob-
tained. The explanation of the above described facts appears to
be found in the assurnption that in the neutral solution there is a
small quantity of basic sulphate together with the normal salt,
which then furnishes traces of cuprous oxide during the electroly-
sis ; or that the latter is formed by reaction upon the already pre-
cipitated copper. According to this explanation the brittleness of
the deposited copper is explained by its content of cuprous oxide.
WORK OF CHASSY, 1894.
Chassy^ furnishes some interesting contributions on this sub-
ject. This investigator found out that using a cathode current
density of i ampere per square decimeter and electrolyzing a sat-
urated copper sulphate solution at 100° C, there was obtained a
red precipitate tarnishing a peculiar blue, and consisting of small
red cubic and octahedral crystals of cuprous oxide, CugO. At
temperatures below 100° C. much copper appears in place of cup-
rous oxide ; at 40° C. and thereunder only the metal is precipi-
tated. Similar results were obtained by Chassy by decreasing the
concentration or the current density.
1 Comptcs rcndus, 1894, 119, Vols. 4-5. 271.
4 MANUFACTURE OF METALLIC OBJECTS
FOEBSTEB'S WOBE ON QUANTITATIVE PBECIFITATION OF
COPPEB.
Very soon after this Dr. F. Foerster published his interesting
communication upon the phenomena of the electrolysis of copper
sulphate solutions, which he brought out in connection with his
studies upon the copper voltameter. Foerster set forth the follow-
ing fundamental laws:^
1. With current densities under o.oi ampere per square deci-
meter the action of the current upon the concentrated copper sul-
phate solution at the ordinary temperature consists in a liberation
of cuprous ions at the cathode. With increasing current densities
more and more cupric ions are completely discharged and rela-
tively fewer cuprous ions produced by the current, without, how-
ever, the production of the latter completely ceasing even at high
current densities.
2. The tendency of the cupric ions of the sulphate solution to
pass over into cuprous ions increases very markedly with the tem-
perature so that at ioo° C. the current produces almost exclusive-
ly cuprous ions at the cathode, even with current densities of 0.03
ampere per square decimeter in a concentrated copper sulphate
solution.
3. The production of cuprous ions can take place in copper sul-
phate solutions without the influence of the current, as in cupric
chloride solutions, by the action of metallic copper upon the cup-
ric ions of the cupric sulphate solution :
Cu + Cu = 2Cu,.
This action proceeds until the cupric sulphate solution is satu-
rated with cuprous sulphate. It is difficult to determine in the
case of copper sulphate solutions to what extent the formation of
cuprous sulphate depends upon this solution of copper or upon
pure electrolytic action ; Foerster thinks the latter to be the simp-
lest and most probable factor.
4. Under similar conditions more cuprous ions will be formed
1 Zeitschr. f. Elektrochemie 3, 480 and 481.
s This fact was established a long time ago by Jakobi (see Wiedemann, Zeitschr. f.
Elektrochemie a, 510) but the knowledge of it apparently had no influence upon
the later developments of the subject.
BATHS FOR COPPER GALVANOPLASTY 5
In a sulphuric acid solution, the greater the concentration of the
cupric ions present.
5- If the solution is neutral the cuprous sulphate produced suf-
fers hydrolysis as soon as its concentration has exceeded a certain
limiting value. The equation of the change is
2Cu + SO, + H^O = Cu,0 + 2H + SO,.
By reason of this reaction cuprous oxide is often separated
upon the cathode in crystals having an adamantine lustre, leaving
in solution free sulphuric acid.
6. If the solution is sufficiently acid no hydrolysis will take
place and much larger quantities of cuprous ions will remain in
solution than if the latter is neutral.
Even in this case, however, there is a limit to the enrichment of
the solution in cuprous salt, for as soon as the relative concen-
tration of the cuprous ions to the cupric ions has passed a certain
limit the former change back to cupric ions thereby separating out
■metallic copper:
+ + +
2Cu = Cu + Cu.
Referring back to the phenomenon of solution described in
paragraph 3, we see that we have a reversible reaction
7. There results at the cathode metallic copper by the above de-
scribed operations from very acid cupric sulphate solutions, also
when the current density only produces cuprous ions.
In the latter case the copper might be regarded as separated out
""'secondarily" and does not form uniform deposits like the copper
separated out in the ordinary way from acid solutions, but ap-
pears in small single, distributed crystals.
8. If the cuprous ions get to the anode they again take up posi-
tive charges and are converted into cupric ions; the current is
then doing at the anode, in a measure as this reaction takes place,
other work than ionizing the anode itself.
As is seen from the preceding paragraphs the current density
used plays an extraordinarily important part even in the correct
solution, no less than the content of acid and the temperature of
6 MANUFACTURE OF METALLIC OBJECTS
the solution. The avoidance of the formation of cuprous ions is
a fundamental condition for quantitative precipitation of copper
and likewise for the obtaining of coherent metal.
Foerster found the results collected together in the following
table when electrolyzing acid and neutral cupric sulphate solutions
of various concentrations with various current densities.
Amp per.
CUS04.
H2S04.
sq. dm.
Properties of the Cathode copper.
2.0
—
13.0
At places powdery
2.0
—
lO.O
Dense, bright red
I.O
I
7.0
Powdery
I.O
I
4.0
Strongly adherent, bright red
0.25
—
I.O
Dark red, powdery
0.25
—
0.7
Beautiful, bright red
0.25
I
1.8
Dark red. powdery
05
—
0.3
Ditto
0.5
—
O.IS
Bright red adherent
In this table the numbers under the headings CuSO^ and
H2SO4 denote the number of gram-equivalents of these materials
present in one litre of the electrolyte (by weight the gram-equiv-
alents are 80 and 49 respectively).
Foerster worked wtih stationary electrolytes and the above
values are valid only for such.
As early as 1857 Magnus^ published a work upon "Limiting
Values of the Current Density in Copper Sulphate Solutions,"
and here we may also refer to the work of Karl Ullmann, who re-
ported upon the influence of time upon the phenomena at the
cathode in the electrolysis of copper sulphate solutions. It would
lead us too far to reproduce at length Ullmann's results, and I
content myself with referring to his very interesting original man-
uscript.^
STUDIES BY HUBL, 1886.
Arthur von Hiibl described in 1886 in the "Mitteilungen des k.
u. k. militar- geographischen Institutes," 6, 51 to 96, his funda-
mental studies upon the properties of electrolytically precipitated
copper, and I extract freely from this communication because the
physical properties of cathode copper are treated with particular
completeness and thus must be of special interest to us. Hiibl
writes :
1 Pogg. Ann. 103, (1857) I to 54.
« Zeitschr. f. Elektrochemie, 3, 516 ct seq.
BATHS FOR COPPER GALVANOPLASTY 7
"If an addition of sulphuric acid is made to the copper sulphate
solution then both copper sulphate and sulphuric acid take part
in carrying the current and both will be decomposed in quantity
corresponding to their conductivities.^ Since the sulphuric acid
is very strongly dissociated in comparison to the copper sulphate
and therefore is an excellent conductor, the addition of only a
few per cent, of acid results in the conducting of the current being
done practically by the acid itself. The separating out of copper
+
at the cathode proceeds as follows: that H precipitates copper
secondarily because of its higher discharge potential, while cop-
per is precipitated primarily only in quantity corresponding to the
dissociated fraction of copper sulphate present.
"If the hydrogen finds at its point of evolution an insufficient
quantity of copper in the solution, that is if the solution is too
dilute in comparison with the quantity of hydrogen produced,
then the latter separates out as free gas and results in a loosely
coherent deposit of copper. This phenomenon is therefore to be
observed ; the lower the current density the more dilute the solu-
tion in copper sulphate and the greater the addition of sulphuric
acid. The beginning of the separation of hydrogen is character-
ized very plainly by the development of a strong polarization by
which the apparent resistance of the electrolyte suffers a sudden
increase.
The Separation of Copper in Granular Porm,
"If the quantity of hydrogen separating out is small in propor-
tion to that of the copper no evolution of gas takes place at the
cathode: the hydrogen apparently combines with the copper,
forming a hydride, which combined with the pure metal forms
a non-homegeneous, powdery, spongy or sandy precipitate of
more or less dark color. Only on further increase of the current
density, doea the quantity of hydrogen set free become so great
that it appears in the form of gas bubbles.
Changes in Concentration During Electrolysis,
"If the concentration of the bath is investigated during the elec-
trolysis at different places it is found to vary and it may be easily
1 This explanation is no longer considered valid. — Translator.
8 MANUFACTURE OF METALLIC OBJECTS
proven that a dilution takes place at the negative pole, and at the
positive pole a concentration of the solution. In the presence of
free sulphuric acid the dilute solution at the cathode will be richer
in acid than the concentrated solution at the anode. Hittorf ex-
plains these changes in concentration, by the assumption that the
ions move with different velocities towards the electrodes (Wiede-
mann, Elektrizitat 3, 548, 942), while the increase of acid at the
cathode is produced by the indirect precipitation of copper by hy-
drogen.
"The concentrated solution is specifically heavier, the dilute
solution lighter than the original, and therefore when the elec-
trodes hang vertical a current of electrolyte rises upwards around
the cathode and flows downwards around the anode. The conse-
quence of this phenomenon is that after some time a layer of very
concentrated solution is found at the bottom of the vessel while at
the surface a very dilute solution and finally only an acid solution
is to be found.
"These facts entail many disadvantages in practice and have to
be very carefully watched when working with vertical electrodes
and are the more in evidence the greater the current density and
the extent of the depositing surfaces.
Inequalities in the Copper Precipitate.
"The current of solution rising at the cathode is divided quick-
ly into single vertical rising parts by the small irregularities found
upon the cathode surface, and since these divided currents vary
in their concentration they produce an unequal distribution of the
current passing to the cathode. There will be therefore formed
vertical lines upon the cathode with gutter-like grooves in be-
tween; the lines grow rapidly and therefore increase the difficul-
ty both in consequence of increasing the differences in concentra-
tion, as also because the projecting lines receive more copper de-
posit than the grooves between them.
"A further consequence of these currents is that the copper
crystals of which every galvanic deposit consists arrange them-
selves in certain directions and thereby make the cohesive strength
of the precipitate different in different directions.
"The layers of liquid produced in time cause the heavy solu-
BATHS FOR COPPER GALVANOPLASTY 9
tions at the bottom of the vessel bathing the lower end of the
anode to cover it with copper sulphate crystals, which, being poor
conductors of electricity, introduce resistance. On the other hand
the different conductivitv of the concentrated and dilute solutions
produce an unequal division of the current, so that finally the di-
lute or simple acid solution on the surface may produce a deposit
•of non-homogeneous copper. For this reason it will always be ob-
served that the lowest lying part of the cathode grows faster than
those parts which are nearer the surface and that the first indica-
tion of the production of hydrogen, namely the precipitation of
■sandy copper, occurs first in the upper part of the electrolyte.
*'In order to get a better picture of the stratification of the solu-
tion, tests were taken at different depths through a bath contain-
ing 19 per cent, of copper sulphate and 3j^ per cent, of sulphuric
acid, during the course of the electrolysis. The size of the elec-
trodes was about 50 centimeters square, the distance apart, 8 cen-
timeters, and the current strength 40 amperes. After running 7
hours three tests taken from between the electrodes showed the
following composition :
1. Test from the surface: 12.7 per cent, copper sulphate, 3.9
per cent, sulphuric acid.
2. Test 25 centimeters under the surface: 21 per cent, copper
-sulphate, 3.4 per cent, sulphuric acid.
3. Test 50 centimeters under the surface: 29.2 per cent, cop-
per sulphate, 3 per cent, sulphuric acid.
Concentration Currents.
"A further evil of the stratification of the liquid is observed if,
after shutting off the current, the electrodes are allowed to stand
in the bath by themselves for several hours. The copper dipping
into the two solutions of different concentration causes concentra-
tion currents which pass from the metal in the dilute acid solu-
tion above, through the liquid to the concentrated solution below
and to the end of the electrode in contact with it, and produce
solution of the upper part of the electrode and deposition upon the
lower part.
"The existence of currents of this kind was first observed by
Buchholz (Gehlens, Journal de Chemie 5, 1808). The upper part
10 MANUFACTURK OF METALLIC OBJECTS
of the cathode of precipitated copper being in dilute acid solution,
behaves after the interruption of the current exactly like an
anode ; its surface is dissolved by SO4. As will be later explain-
ed at length, there fomis, however, on the surface of each anode
a loosely coherent dark colored deposit which, when electrolysis
is resumed after an interruption, prevents the newly precipitated
metal from uniting perfectly with that earlier precipitated. In
consequence of this phenomenon which repeats itself at each in-
terruption of the current, the copper precipitated may consist of
several loosely coherent layers.
"All the difficulties which are met with in practice in conse-
quence of the inequalities in the solution may be overcome in two
simple ways : through a mechanical arrangement for a continual
mixing of the bath or by arranging the electrodes horizontally.
Maximum Current Density.
'"As has already been mentioned, there is formed during elec-
trolysis, if a certain current density is exceeded, a non-coherent
precipitate caused by the free development of hydrogen. This is
very evidently perfectly useless for practical purposes. But since
it is on the other hand very desirable to hasten the galvanoplastic
processes as much as possible it is necessary to make use of higher
current densities. It is therefore of the greatest value to know
this maximum current density which may be used in those baths
of different composition, and still produce with certainty fault-
less, strong and flexible precipitates.
"The results of experiments in this direction are contained in
the following table which gives the current densities at which free
hydrogen is evolved, immediately upon the closing of the circuit.
This is evidenced both by the occurrence of the already describ-
ed polarization as well as by the occurrence of non-homogeneous
dark metallic deposits.
Concentration of
the solution in
CUSO4
Per cent.
Current density
Normal.
at which the evolution of h5-drogen begins,
amperes per square decimetre.
0.6 ^ H2SO4. 3.0 ^ H«S04. 6.0 ^ H2SO4
I.O
0.32
• * * .
• • • •
• • • •
2.5
1.20
080
0.68
• • • •
5.0
2.60
T.60
1.44
1.40
10.
15-0
5.12
7.80
• • • •
• • « •
3-40
5-72
3.20
4.60
20.0
10.20
• • • •
7.08
6.00
BATHS FOR COPrE;R GALVANOPLASTY II
*'From this table it is to be concluded that :
1. The allowable current densities are approximately propor-
tional to the concentration of the solution.
2. A very small addition of sulphuric acid lowers very much
the allowable current density, while a further addition of acid ex-
-ercises a relatively small influence. This fact is explained very
simply by the relatively higher conductivity of the sulphuric acid.
If to a 20 per cent, solution of copper sulphate, i per cent, of sul-
phuric acid is added it will share to an equal extent in the con-
duction of the current ; while with 5 per cent, of sulphuric acid
the acid does practically all the current conducting. It the last
case almost all the copper precipitated is separated out second-
arily : therefore, a still further addition of sulphuric acid must be
almost without influence.
"In practical galvanoplasty a number of conditions arise, how-
-ever, which influence very unfavorably the current densities
Avhich can be used in practice.
"To start with, it must be observed that the solution at the
negative electrode and at the surface of the bath becomes poorer
in copper ; and that, therefore, the development of free hydrogen
may occur often when using current densities below the normal
maximum value, if the copper content of the layer of liquid be-
comes so decreased by electrolysis that it no longer suffices to
furnish copper in exchange for hydrogen. In consequence of this
condition it is scarcely possible in practice to use more than one-
"half, usually only one-third, of the above given values of current
'densities. If, however, active circulation of the fluid is provided
for, so that the negative electrode is continually supplied with new
•copper sulphate solution, faultless precipitates will be obtained up
to the maximum values given. With very energetic agitation of
the solution even these numbers can be greatly exceeded, since
investigations on a small scale have shown that with these condi-
tions a one per cent, neutral bath may be worked with 0.8 am-
pere, a 20 per cent, solution with 18 amperes current density and
still give practically useful deposits. From practical considera-
tions, however, only a very gentle agitation of the bath is possi-
l)le, in which case the use of one-half to two-thirds of the maxi-
mum density named appears to be all that is allowable.
12 MANUFACTURE OF METAIXIC OBJECTS
"From these remarks it appeafs that the highest current den-
sity practicable in galvanoplastic practice is between the following
limits.
Maximum current
density practicably al-
lowable for solutions in
Composition of the bath. amperes per square
'^ decimeter.
In gentle
At rest. motion,
amperes, amperes.
15% copper sulphate, neutral 2.6-3.9 3.9-5.2
15% copper sulphate -f- 6% sulphuric acid .. .. 1.5-2.3 2.3-3.0
20% copper sulphate, neutral 3 •4-5' i 5- 1-6.8
20% copper sulphate -f 6% sulphuric acid 2.0-3.0 3.0-4.0
"The current density could be still further increased if it were
possible to use a more concentrated copper solution, which, how-
ever, is not practicable when using copper sulphate because on the
one hand the solubility of this salt is very noticeably diminished
by the addition of the necessary sulphuric acid, and because on
the other hand the concentration of the liquid layer around the
anode increases during the electrolysis and yet must always pos-
sess the capability of dissolving the newly formed sulphate.
Solubility of Copper Sulphate.
"The solubility of copper sulphate in dilute sulphuric acid of
different concentrations has been determined experimentally at
55° C. and gave the following results:
In the presence of 0% H2SO4 i liter of saturated solution contains 39-
gms. CUS04.
In the presence of i % H2SO4 i liter of saturated solution contains 348
gms. CUSO4.
In the presence of 2% H2SO4 i liter of saturated solution contains 308-
gms CUSO4.
In the presence of 3% H2SO4 i liter of saturated solution contains 280
gms. CUSO4.
In the presence of 4% H2SO4 i liter of saturated solution contains 260
gms. CUSO4.
In the presence of 5% H.2SO4 i liter of saturated solution contains 253.
gms. CUSO4.
In the presence of 6% H2SO4 i liter of saturated solution contains 245
gms. CUSO4.
In the presence of 8% H2SO4 i liter of saturated solution contains 231
gms. CUSO4.
BATHS FOR COPPER GALVANOPLASTY 1 3
In the presence of io% H2SO4 i liter of saturated solution contains 215
gms. CUSO4.
In the presence of 12% HjSO^ i liter of saturated solution contains 197
gnis. CuSO^.
In the presence of 14% H2SO4 i liter of saturated solution contains 180
gms. CUSO4.
"It is to be seen from these figures that in the presence of 4 per
cent, of sulphuric acid not more than 26 per cent, of copper sul-
phate can be dissolved, and therefore a solution of this concentra-
tion can no longer be used. For a gently agitated bath a solution
containing, at the highest, 20 per cent, may be used ; but in a bath
not stirred separation of crystals on the anode will begin even at
this concentration if the highest curent densities are used and 4
per cent, of sulphuric acid is present. It is finally self-evident
that the temperature of the bath may also exert an important in-
fluence upon the above described conditions and under some cir-
cumstances may also be the determining factor of the allowable
current density.
ni. PHYSICAL PROPERTffiS OF THE COPPER
DEPOSIT.
The endeavor of galvanoplastics must be to produce a copper
deposit with properties suitable for the purpose desired, — that is,
with certain definite physical properties. Since these properties
must be within certain limits, it is necessary to know those factors
which determine the qualities of the deposits obtained.
INFLUENCE OF FOREIGN ADMIXTURES.
The views on this subject are contradictory. This is explained
by the great difficulties which are experienced in carrying out
such investigations. The properties of the deposit are without
doubt often very largely influenced by secondary processes con-
nected with changes or small impurities in the bath, and it is often
impossible to recognize and trace out to their limit the phenomena
in question. If we take into consideration the changes which cop-
per, like other metals, undergoes through the presence of traces of
foreign bodies, for instance even by cuprous or cupric oxide, there
can be no doubt that similar considerations must be of an import-
ant influence upon the properties of the galvanic deposit. There
is no doubt of this in the case of deposits gotten from the acetate
or from cupric chloride, as also from basic copper solutions.
STRUCTURE.
Aside from the secondary processes taking place and the influ-
ence of impurities in the bath, the physical properties of the cop-
per are considerably influenced by the structure of the same.
The structure is crystalline but the single crystals are more or less
developeed. This consideration as well as their orientation must
determine largely the strength, elasticity and hardness, etc., of the
metal.
Since the metal is separated from a copper solution by the elec-
tric current, the structure of the crystalline aggregate must be
determined by two factors; composition of the bath, and current
strength.
PHYSICAL PROPERTIES OF COPPER DEPOSITS IS
Two views have been advanced respecting the influence of these
two factors. One was advanced by Smee and is summed up in the
statement: current density and concentration of the bath deter-
mine by their relative proportions the quality of the metal. The
second view was given by F. Kick as follows : the quality of the
galvanic deposit is dependent upon the composition of the elec-
trolyte and independent of the current density.
Smee, upon the basis of his numerous investigations, comes to
the following conclusions :
1. The metal is separated out in a non-homogeneous form
(powdery, spongy, or sandy) if the current strength is so great
that evolution of hydrogen occurs simultaneously with the deposi-
tion of the metal.
2. The metal is separated out in a coarsely crystalline form if
the current strength is far from being sufficient to cause evolu-
tion of hydrogen.
3. The metal appears as a tough, solid, fine-grained deposit if
the current strength is as great as possible, but not strong enough
to cause evolution of hydrogen.
Smee therefore concludes that by the application of proper cur-
rent density it is possible to obtain deposits having certain proper-
ties from baths of almost any concentration.
H. Meidinger (Dingier p. J. 218, 219) reviews the conclusion
of Smee and adds this statement: "The relation of the current
density to the concentration of the solution is a constant for a
determined quality of the precipitate, but the limits are not very
sharply defined. If a deposit of certain properties is obtained
from a concentrated bath a similar precipitate might be obtained
from a bath of half the concentration by half the current strength,
from a bath of one-third the concentration by one-third the cur-
rent strength, etc."
Hiibl made extensive experiments to find the most suitable re-
lations for producing the best precipitates. His preliminary ex-
periments on a small scale, to determine the appearance and the
brittleness of the precipitates, were carried out as follows :
HiJBL'S INVESTIGATIONS.
The copper sheets used as electrodes were 50 mm. wide, 100
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PHYSICAL PROPERTIES OF COPPER DEPOSITS I7
-mm. long and held at a distance of 20 mm. apart by suitable sup-
ports. The cathode was silvered and slightly iodized in order to
facilitate loosening of the precipitate. A glass beaker filled with
the experimental solution was brought under the electrodes and
raised until the latter dipped 50 mm. into the solution. Daniell or
Bunsen cells served as the source of current, a circular rheostat
In the circuit serving to regulate the current strength. When ex-
periments were to be made with agitated baths the desired agita-
tion was obtained by the bubbling in of air.
Two pairs of electrodes were always in the circuit, one pair
dipping into a 5 per cent., the other into a 20 per cent., solution
of copper sulphate.
At first so-called neutral solutions (boiled with copper carbon-
ate) were electrolyzed, using various current densities, the solu-
tion being replaced after each experiment in order to produce no
Irregularity by the change in the composition of the bath.
NEUTRAL SOLUTIONS.
It follows from these results that, using a so-called neutral solu-
tion and a smaller current density in a 5 per cent, bath, better
precipitates are obtained than in a concentrated solution, while the
appearance of the metal in both cases is the same. The cause of
this phenomenon has already been alluded to. The addition of
sulphuric acid hinders the formation of large crystals. There are
therefore obtained with small current densities very finely granu-
lar, tough deposits whose texture and behavior in bending are in-
dependent of the concentration of the solution.
The more or less crystalline texture appears as well with so-
called neutral as with acid baths, depending entirely upon the cur-
rent strength used. The coherence of the metal which is to some
extent shown by its behavior on bending agrees completely with
the development of the crystals in acid baths, but in neutral solu-
tions appears to be determined almost entirely by the basicity of
tlie solution.
In order to obtain a useful deposit the current density used
sTiould not exceed a maximum already stated, as determined by
the concentration of the bath ; within this limit, however, the cur-
rent density is the only determining factor of the texture and the
properties depending upon the texture.
l8 MANUFACTURE OF METALLIC QBJECTS
THE ACTION OF ADDITIONS.
The reason why only finely crystalline deposits are obtained
when acid is added has so far not been explained. Meidinger at-
tempted an explanation, according to which the cause was the in-
direct separation of the metal, but in this case similar influences
should be exerted by other substances. If to a lo per cent, so-
called neutral bath there is added lo per cent, of sodium sulphate,,
there must in this case according to the conductivity of the latter,,
"certainly be a large part of the copper separated out indirectly by^
the sodium. But with a current density of 0.8 of an ampere such
a solution gave a quite as coarsely crystalline and fragile deposit
as without this addition.
ADDITION OF SULPHURIC ACID.
Concerning the quantity of the sulphuric acid added, experi-
ments on this point show no difference in the texture of the pre-^
cipitate when 2 to 8 per cent, of acid was present.
TENSILE STRENGTH.
The determination of accurate values for the tensile strength of
galvanoplastic deposits is attended with extraordinary difficulties
and in spite of serious attempts it was not found possible to obtaia
complete correspondence between the numbers found and the var-
iations in the method of producing the deposit.
A great difficulty is primarily in the production of perfectly
faultless plates of dimensions large enough to make the tests on
them. Irregularities in the growth of the precipitate (the forma-
tion of copper granulees which when removed show a changed
structure at the point where they have been removed) influences
self-evidently the numbers found by the testing machine.
Experience has, however, shown that copper of smaller
strength is deposited from old baths. The reason of this phenom-
enon could not be explained, since the chemical analysis of the old
baths with the exception of a trace of cuprous salt, showed na
differences from the new baths just going into use. It appears-
highly probable that the turbidity of the baths which have been
used, caused by the particles of anode slime in suspension, exert
a prejudicial influence on the precipitate. It is also, however, very^
PHYSICAL PROPERTIES OE COPPER DEPOSITS IQ
probable that substances coming from the lining material of the
cell, as lacquer upon the back of the cathodes, contaminate the
"baths.
For this reason the following results, which have been taken
from copper specimens precipitated from long used baths, do not
represent the best obtainable results and can on these grounds
only be regarded as values for comparison among each other.
The method of the production of the specimens was as follows :
A layer of copper 0.8 to i mm. in thickness was deposited by a
carefully measured current from a dynamo machine, upon a
smooth silvered copper plate of proper dimensions, covered on
the back with an asphalt varnish. The current density was cal-
culated from the current strength and the size of the plates. Two
sheets each 50 mm. wide were cut from the middle of the plate in
a determined direction and subjected to a tensile test.
TENSILE STRENGTH TESTS.
The table in the appendix contains the average values gathered
from two series of investigations.
Considering first the values for each test obtained from baths
of similar concentration, the following conclusions may be drawn :
1. The absolute strength increases with the clirrent density.
With not quite pure baths the differences are smaller than when
using freshly made up solutions. The relatively highest values
appear to be obtained with a current strength of 2.2 to 3 amperes ;
-with still higher densities the absolute strength decreases. This is
explained by the fact that 4 amperes is in the neighborhood of the
practically allowable current density, and at this strength the ten-
dency becomes manifest to separate out sandy copper. This
phenomenon will also occur in a short time if the agitation of the
"bath is ceased and it is allowed to stand quiet.
2. The elastic limit and elongation show a maximum with cur-
rent strengths of i.o to 1.5 amperes.
3. The toughness of the metal, represented by the elongation at
rupture, decreases with increase of current strength.
The maximum value lies below a density of 0.6 ampere, yet
it might be supposed that with very small densities the toughness
would decrease because of the appearance of a more crystalline
structure.
20 MANUFACTURE OF METALLIC OBJECTS
4. The hardness increases with the current density. It is to he-
observed that the method of determining hardness gives correct
results with thick plates, but that with thin sheets deformatioir
may occur, making the method of the determining of the hardness-
unreliable.
Discussing the relations between the above properties and the-
concentration of the bath it may be observed that :
1. The absolute strength is almost independent of the composi-
tion of the bath. The results of the series of experiments with
freshly made up baths are very plainly different from those with
old baths ; but in each group similar current densities correspond*
to nearly equal tensile strengths, independently of what concentra-
tion was used in the bath. These values are graphically set fortlr
in connection with the table.
2. The elastic limits and the elongations sliow undoubtedly the
influence of the concentration of the bath ; since as the latter de-
creases these physical values decrease also.
3. The values for the toughness show such irregularities that
the correspondence between it and the concentration of the bath
is scarcely to be recognized. Tests 10 and 11 in particular are
quite isolated from the others. The other values allow of conclu-
sions respecting the variation of toughness with current density
alone, but there are some vStriking relations between the properties
of the precipitate and the ratio of the concentration of the bath ta
the current density.
The results are given further on. The following additional ex-
planations may be added :
The elastic limit given under i and 2 is expressed by the num-
ber of kilograms which a bar of one square centimeter cross-
section can support without producing a permanent elongation of
0.0000 1 or 0.000 1 respectively of its length.
The hardness is expressed by the length of a nick which is pro-
duced by a chisel upon which a certain weight is allowed to fall.
The longer nick corresponds therefore to a relatively softer cop-
per, and conversely.
The sheets distinguished by J are taken from vertical hang-
ing plates in a vertical direction. Those divStinguished by w-*
are cut in a horizontal direction. There was thus obtained as
relative hardness :
((
((
( t
PHYSICAL, PROPERTIES OF COPPER DEPOSITS 21
No. 15 = 19.4 from a 20% bath and 4.00 amp/sq. dm.
No. 18=19.4 " •' isfc *' " 3.23
No. 20=17.2 •* '* 10% " •* 1.50
No. 21 = 19.7 " •* 5% " •• 1.30
It is to be remarked that defects in the material would be of
great influence upon the length of the sheets after rupture, which
circumstance may be the cause of some of the irregularities which
the values of the toughness show.
From these investigations it must be concluded that practically
the current density, partly also its relation to the concentration of
the bath, determine the strength and elasticity of the galvanic de-
posit. If the entire electrolytic process proceeded perfectly it is
highly probable that the qualities of the deposit would depend
upon the current density only ; this would determine the crystal-
line texture of the product and the mechanical properties would
be in correspondence with it. But since without doubt second-
ary processes occur during the electrolysis, the intensity of which
depend upon the relation of the current density to the concentra-
tion of the bath, the latter factor must also influence the qualities
of the precipitated metaL
For practical purposes the following rules may be developed
from the above facts:
1. If copper of the greatest tensile strength and hardness is to
be deposited and less weight is laid upon great toughness, high
current densities of 2 to 3 amperes per square decimeter should
be used. The electrolyte must in this case evidently be as con-
centrated as possible (20 per cent.).
2. If copper of the greatest possible toughness is desired, and
hardness and strength are of less importance, current densities of
0.6 to I ampere are suitable. The electrol3ie would be a i6 to i8
per cent, solution.
The absolute tensile strength of a good galvanic deposit approxi-
mates that of cold-hammered plate and its elastic limit in some
tests has gone considerably higher.
As far as toughness is concerned the galvanic deposits are con-
siderably superior to the rolled metal. This is very well deserv-
ing of notice.
As is shown in experiment No. 12, the cohesion of the precipi-
22 MANUFACTURE OF METALLIC OBJECTS
tate upon a vertical hanging plate is not the same in all directions.
Tensile strength, elastic limit and especially the toughness are
greatest in a vertical direction. This circumstance is only to be
explained by the orientation of the crystals, which is influenced
by the upward flowing current of electrolyte. This fact is also of
practical value in that it is sometimes desirable to put the articles
being produced in such position in the bath so as to produce the
above effects in certain desired directions. Copper plates for en-
graving are therefore always to be produced in such manner that
the strongest cohesion of the metal lies in the direction along
which the plate passes in the ])rinting press.
Experiment No. 23 is made with a plate produced with the
greatest care in a Daniell trough apparatus. The apparatus was
charged with the so-called English vitriol; the measured current
strength was 0.25 ampere. The absolute tensile strength and
toughness are in fact lower than those made with dynamo-electric
machines, yet this precipitate is to be regarded as a particularly
fine one in view of the manner in which it is made.
Appendix V of Hiibl's "Original-Abhandlung" shows the de-
formation which different precipitates suffer under the tensile
tests. Tests 2 and 3 are well worthy of notice ; for they have a
higher elastic limit than refined copper, and yet show a surpris-
ingly good behavior on rupture.
Foerster and Seidel^ took these questions up later and obtained
results in complete accord with those of Hiibl. They discovered,
however, an important new factor; z>ic., the influence of the tem-
perature of the electrolyte upon the physical properties of the cop-
per. The following values were found :^
Temperature of Ihe Average bath-tetision.
Electrolyte in °C. Volts
20 0.;2
40 0.25
60 0.20
Drawn wire from Mansfield
electrolytic copper.
It appears therefore that the temperature of 35 to 40° C. is the
» Zeitschr. f. Elektrochemie 5, 508 et seq.
* These numbers represent the length of a wire of the metal in Kilometers which
will support its own weight. These tests were made at the Mechanical Institute at
Dresden by Dr. Hariig.
Rflative tensile
streniith-.
Toughness Per cent
elongation at
rupture.
2.>5
9.12
2.67
26.00
2.69
13 50
2.83
31.00
PHYSICAL, PROPERTIES OF COPPER DEPOSITS 23
most suitable, while an elevation above this causes a decrease in
tensile strength of the copper. The reason of the favorable action
of the higher temperature upon the structure of electrolytic cop-
per was not definitely known. Foerster^ is of the opinion that
the temperature of the solution determines the size and regularity
of the small crystals of the deposit and thus determines its struc-
ture ; he conducted two experiments in a bath which contained an
amount of Glauber salt equivalent in amount to the copper sul-
phate present, along with the usual amount of sulphuric acid.
Toughness. Per cent
Temperature of the Tensile strength elongation at
electrolyte in °C. (relative). rupture.
20 2.46 15.20
40 1.96 10.82
From this it is to be concluded that when alkaline sulphate is
added, the increased temperature influences unfavorably -the phy-
sical properties of the copper, while on the other hand, the re-
sults at 20^ C. were better with the addition of alkaline sulphate
than without it.
The galvanoplastic baths in ordinary use at present are made
up according to the principles above explained, and Hiibrs and
Foerster's investigations, which furnished the foundation for the
present stage of development. Later investigations have been
concerned mostly with increasing the speed of deposition of the
copper precipitate and the copper baths in practical use at present
have been modified according to the principles discovered by Carl
Polenz and the author,^ and give precipitates much more quickly
and yet without a deterioration of the quality of the cathode cop-
per.
RAPID DEPOSITION.
While Carl Polenz used a solution containing 350 grams of
copper sulphate in a liter of water and warmed to 30° C, the
author used a bath of the following composition :
Water • • i liter
Copper Sulphate 250 grams
Sulphuric acid...: 7.5 grams
Alcohol 5 grams
1 Zeitschr. f. Elektrochemie 5, 511.
2 Wilh. Pfanhauser: " Elektroplattierung, Galvanoplastik und Metallpolierung."
4th Ed., 1900.
24 MANU]?ACTURE OF METAI^WC OBJECTS
This bath possesses a specific resistance of t.6 ohms and a tem-
perature coefficient of 0.0096. The temperature was about 20°
C. ; yet higher temperatures, such as are produced by high current
densities, up to 10 aniperes per square decimeter, are quite harm-
less if they do not exceed 30° C. ; in fact, they exert a favorable
influence on the precipitate. The electrolyte vvas kept in motion
by an air blast, thus furnishing concentrated copper solution con-
stantly to the cathode and at the same time cooling the solution
so as to dispense with the use of cooling water.
OI,D BATHS.
The bath formerly used for galvanoplastics was composed of
Water 1 liter
Copper sulphate 200 ^rams
Sulphuric aci( 1 30 grams
Specific resistance 0.93 ohm, temperature coefficient 0.0112.^
POWER REQUIRED FOR COPPER PRECIPITATION.
If the relative currents are compared, as required for the usual
bath and for the rapid deposition bath of Pfanhauser, the power
required to deposit one kilogram of copper, the distance between
the electrodes being 10 centimeters, is as follows :
Current density in
amperes per
square decimeter.
Inordinary galvano-
plastic bath.
Horsepower — Hours.
In Pfanhau.<ier's rapid
galvanoplastic bath.
Horsepower— Hours.
0.5
0.67
• • •
I.O
1.34
• • • •
1-5
2.01
• « • •
2.0
2.68
4.60
3.0
6.90
4.0
9.20
50
6.0
It. 50
i3.«o
7.0
i6.ro
8.0
18.40
9.0
20.70
lO.O
23.00
The power requirement is proportional to the specific resist-
ance of the electrolyte as long as no polarization phenomena ap-
pear, that is as long as no counter electromotive force complicates
the calculation. If the Pfanhauser rapid deposition bath is kept
in use for a long time the electrolyte becomes impoverished in
free sulphuric acid and therefore acid must be added from time
to time.
^ As measured by the author.
IV. BEHAVIOR OF COPPER ANODES.
anode: sumk.
In this field Hiibl has also made some skillful observations, and
Foerster also has given extensive communications on anode slimes
in the baths. Max Herzog von Leuchtenberg has also written
concerning the slime residue. Commercial copper, not electroly-
tic, may contain impurities of the most different elements, of
which I may mention, Au, Ag, As, Sn, Pb, Fe, Ni, S, etc., which
are usually known outside of the copper refinery.
But the electrolytically produced copper, if it has not been roll-
ed before being used as an anode, also furnishes a reddish slime
which was investigated as early as 1875 ^Y Kick.^ He deter-
mined that it contained about 60 per cent, of metallic copper and
40 per cent, of cuprous oxide, CuoO.
Hiibl does not agree with Kick for he writes: "If what F.
Kick observed is correct, a part of the SO4 radicle liberated at
the anode would have to form free sulphuric acid and oxygen.
In that case the content of the bath in free sulphuric acid would
increase after long use." Since the quantity of the slime formed
when using electrolytic copper as anodes is in considerable
amount, it was interesting to further investigate this phenomenon.
As far as commercial copper plates were concerned the results
obtained substantiate completely those of Leuchtenberg. The
quantity of black slime produced depends almost solely upon the
purity of the metal and is quite small when using the better grade
of copper at present found in commerce. Using electrolytically
produced anodes, however, there appears to be produced a much
larger quantity of a light brown slime which was found to be
completely free from foreign metals. After washing and drying
there remains a heavy, dense, brittle mass, readily taking a cop-
pery lustre when polished. Under the microscope it was seen to
be almost entirely composed of more or less well preserved cop-
per crystals.
1 Dingier Pol. J. ai8, 219.
26 MANUFACTURE OF METALLIC OBJECTS
COMPOSITION OF THE ANODE SLIME.
Using pure anodes deposited electrolytically, repeated chemical
analyses of the residues showed them to consist only of pure cop-
per. The method of Hampe,^ the determination of the loss of
weight by ignition in a current of hydrogen, was used for the de-
termination of the oxygen present in the residue. In two tests no
oxygen at all could be found, and therefore CugO could at most
only have been present in traces. If the washing and drying of
the copper slimes has not been done with the proper care it be-
gins to take a yellow color and in that case considerable quanti-
ties of CU2O can be found. A test of a partly oxidized slime of
this nature showed a content of 4.7 per cent, of CU2O.
The residue from galvanic deposited anodes consists therefore
of microscopically small copper crystals which have the property
when used as an anode of remaining unaltered. It is highly
probable that they really exist in a passive state which may be
due to an extremely thin coating of cuprous oxide, CU2O, not de-
tectable analytically. Only galvanic deposited copper shows this
phenomenon, which may be explained by its quite characteristic
crystalline structure.
INFLUENCE OF THE ANODE SLIME ON THE PRECIPITATE.
This copper slime thus formed is a highly undesirable material
for the gaivano-plater, since it causes a turbidity in baths which
are agitated, becomes entangled in the precipitated copper, causes
rough surfaces and lowers the cohesive strength of the metal.
On these grounds it is desirable to use commercial rolled cop-
per plates in preference to the electrolytically deposited.
All the observations so far made concerning anode slime relate
to acid baths. When using the so-called neutral baths the forma-
tion of cuprous oxide, CujO, can be actually observed, particu-
larly when high current densities are used. The anode in this
case becomes at places plainly reddish yellow and under this con-
dition the bath shows a change in its acidity after the electrolysis.
Foerster also finds only a small amount of cuprous oxide, CujO,
and determined that it consisted likewise of small crystals of pure
copper. He explained the formation of these small crystals by
1 Zeitschr. f. anorgan. Chemie 13, 202.
BEHAVIOR OF COPPER ANODES 27
the increase in the concentration of the solution in the neighbor-
hood of the cathodes which were surrounded loosely with parch-
ment paper; and by the tendency of the anode copper to furnish
copper ions to the solution, producing in the immediate vicinity of
the anode cuprous sulphate, CU2SO4, which decomposed sponta-
neously into cupric sulphate, CUSO4, and the crystalline precipi-
tate of copper.
-I- + +
2 Cu=Cu
+ + +
Cu-fCu = Cu2S04,
+ +
Cu,S04 = CUSO4 + Cu.
POLARIZATION PHENOMENON.
The author has observed that when using envelopes of parch-
ment paper, silk, etc., around the anode the current strength falls
soon after closing the circuit, instead of remaining constant, and
in this case reaches constancy only at a small fraction of an am-
pere. But since it is desirable at times to keep the anode slime
out of the body of the electrolyte, particularly when the baths are
agitated, in order not to interfere with the physical properties of
the precipitated copper, 1 began investigations to find a suitable
envelope which would be close enough to retain fine slime and on
the other hand sufficiently porous to keep down the tendency to
increased concentration inside the envelope, which occurs par-
ticularly with high current densities. Flannel not too tightly
woven w^as found to be the only suitable material. Using current
densities of even 8 amperes per square decimeter and envelopes
of this material, there was no sign of the falling off of the cur-
rent after closing of the circuit and the solution remained clear
of slime even when the so much feared electrolytic anodes were
used. In this manner, plates 4 to 5 millimeters in thickness were
produced, using current densities of 8 amperes per square deci-
meter and having only very small unevenness on the depositing
surfaces.
V. CONSTANTS OF THE BATH AND CALCU-
LATION OF THE AMOUNT OF DEPOSIT.
The operation of plants for the electrolytic manufacture of me-
tallic objects must be so arranged, it will be admitted, that even
the workmen may be able to determine at once whether their
baths are working or not. For this reason, each bath must be
supplied with an ammeter and a voltmeter, as well as, when neces-
sary, a regulating resistance either in series or in parallel with
the bath; we will speak later of this. Since the ordinary work-
man having charge of the bath cannot be expected to be able to
calculate specific bath resistances, current density, etc., it is neces-
sary to give him precise data concerning the proper indication of
his instruments, from which he can draw conclusions concerning
the correct working of his bath. On the contrary, the constants
of the bath should be known to the person in charge, and I will
therefore at this place recapitulate briefly the methods of deter-
mining them.
DETERMINATION OF THE SPECIFIC RESISTANCE.
In Fig. I, AA, indicates a stretched wire of *'constantin" serv-
ing as a measuring wire and provided with a millimeter scale.
B
i^
■^
w
D
/wwv\
K
T
a_
I I I I i i ' I ' I I I I ' ' i I
wwwwww
/wwvu
Fig. I.
From the point A a conductor leads to the Arrhenius cell W,
which contains the electrolyte to be investigated and whose other
pole is in connection through B with the plug rheostat R, and
CAIXULATION OF THE AMOUNT OF DEPOSIT 29
i:hrough it to the other end A, of the measuring wire. Between
the point and the movable wire contact K there is inserted a Bell
telephone T, which gives a sound by means of the alternating cur-
rent generated in the induction coil, so long as a current flows
through the telepone. By suitably changing the resistance in R
and sliding of the contact K, the current through the telephone
can be brought to zero when the potential fall through BR is
•equal to the potential fall through the other side of the circuit.
The relation of resistance at this point is therefore
^ ~ R
the latter reading being the relation of the distances AK and Ai,
K, respectively, as measured in millimeters, and on the further
assumption that the measuring wire has a constant resistance for
uniform distances on the scale. ^ (F'or the most accurate work the
measuring wire should be calibrated). From the above propor-
tion the resistance of the cell W between the two platinized elec-
trodes of the Arrhenius vessel is calculated, that is
a
Resistance of cell =7- X Resistance of plug rheostat.
o
W being known, the determination of the specific resistance of
the electrolyte, R^, taking as a practical unit^ a cube of the
fluid one decimeter on a side, may be found by dividing R by the
resistance capacity K of the measuring vessel, in which K is the
ratio of the length to the cross-section of the electrolytic resist-
ance measured, this proportion being called the resistance capacity
of the measuring vessel. This proportion can be gotten by meas-
usement, or by an experimental determination by placing in the
vessel a fluid of known specific resistance, and measuring the re-
sistance of the vessel, so that the actual resistance divided by the
specific resistance of the fluid gives the ratio K for the vessel
used.^
I See Kohlrausch and Holborn.
> The specific resistance of fluids is usually expressed in the tables as that of a centi-
meter* of the liquid, which value is ten times the value Rj chosen as the unit by
Mr. Pfanhauser and attention should be paid to this difference when using^
Pfanhauser's formula and taking the specific resistance from the ordinary
tables.— Translator .
30 MANUFACTURE OF METALLIC OBJECTS
As an example, the resistance K of an Arrhenius cell was found
to be 0.2, and the actual resistance of the unknown fluid was 0.3
ohm, from which the specific resistance of the unknown fluid was-
o. "l
calculated to be — ^ =1.5 ohms.
0.2
For further details to be observed in this measurement, such as
the choice of the calibration fluid, choice of the form of the meas-
uring vessel, etc., reference is made to the work of Kohlrausch.
and Holborn, "Das Leitvermogen der Elektrolyte."
CALCULATION OF THE BATH TENSION.
When one knows the specific resistance of the electrolyte, then^
if the distance of the electrodes apart and their sizes are carefully
measured, the total resistance of the bath R* is equal to the
specific resistance multiplied by the length of the bath between;
the electrodes and divided by its cross-section.
In this formula s is the active cross-sectional area of the elec-
trolyte and / the mean distance apart of the electrode surfaces
from each other expressed in square decimeters and decimeters-
respectively. In order to send through the bath with a resistance
Ri, a current of A amperes, a potential difference V volts is nec-^
V = AR = A.R, —
essary. If — is assumed to be the current density per square
s
decimeter (ND/ioo) and if the alteration of the resistance with
the temperature is taken into account, we have the relation
V = ND,oo-/-R. (i±«0
If the counter electromotive force V^ enters into the galvanic
process, its amount (expressed in volts) appears on the right side-
of the above equation; so that the expression for the total bath-
tension will be
V = ND^oo-/. W, (I ± a t) + V^.
GROWTH IN THICKNESS OF GALVANIC DEPOSITS.
To calculate the growth in thickness of galvanic deposits the:
CAL,CUIvAT10N OF THE AMOUNT OF DEPOSIT 3 1
■current density used and the duration of the electrolysis are the
•determining factors. A third factor is the electrochemical equiv-
alent of the metal being precipitated from the solution used.
There are, for instance, two different rates of precipitation of
copper according to whether it is precipitated from cuprous or
•cupric salt solutions. According to Faraday's Law, 96,540 cou-
lombs separate a gram-equivalent of metal, or in round numbers,
26.8 ampere-hours are necessary, as a practical unit.
So the amount of copper precipitated by an ampere-hour is
.3.272 grams from a cuprous solution and 1.186 grams from a cup-
ric solution.
The amount of metal precipitated in a given time t in hours by
a given current A in amperes and with an efficiency in precipita-
tion e expressed in percentage, would be, calling the amount of
metal precipitated by one ampere-hour W.
W=Wi.A.^
100
[This value of W, would be 3,600 times the usual electrochem-
ical equivalent of the metal; that is, the amount precipitated by
one ampere-second or one coulomb. — Translator.]
Calling D the specific gravity of the precipitated metal, the
thickness T in millimeters of the metal deposited on the cathode
of surface S
I — -- — mm,
S.D.iooo D-iooo
From this equation any single value can be easily obtained ; thus
for instance the time in which a given current density must act in
•order to obtain a deposit of a given thickness
T.D-iooo
-W,.(ND,J^
The current density to be used (ND/ioo) will be expressed by
the formula
. - _ T.D.iooo
The subsequent tables contain numerous examples and refer--
-ences may be made to them.
VI. INDUSTRIAL PLANTS.
Before passing to the practical operation of the different pro-
cesses, I will give a few further fundamental points concerning
the equipment of the plants, such as may not be unwelcome to the
manufacturer.
SOURCE OF CURRENT.
First of all concerning the source of current, there is seldom
above 15 volts tension needed at the dynamo-machine because
greater tensions are unsuitable from the danger of the ground-
connection which may be made tiirough the tanks. We are deal-
ing also with well conducting solutions and during the manipula-
tion of the cathodes, their taking out and putting in, naturally-
some of the fluid is spilled and may cause ground connections.
TANKS.
The tanks for electrolytic use are almost universally made of
larch or pitch pine wood, vessels of earthenware or cement being
seldom used. The wooden vessels have as their greatest advant-
age the slight danger of being broken, and besides auxiliary ap-
paratus can easily be fastened to wooden tanks ; for instance, stir-
ring apparatus and the like.
Fig. 2 shows a wooden tank such as is used in the manufacture
INDUSTRIAL PLANTS 33
of metallic papers. Such vessels are usually rated according to
contents and the following table gives the approximate prices
which the various sizes cost, on the average, per unit of contents.
Cost per liter of
Capacity. capacity.
loo liter 7.5 cents
100—150 5.0
150—200 4.5
200 — 250 4.0
250—300 3.5
300—400 3.0
(C
i(
(t
C(
(C
((
400—500 2.7
i 500 — 600 2.5 **
j 600—800 2.2 "
800—1000 2.1 '*
Over 1000 1.7 — 2.0 **
It is recommended to set all tanks on a cement floor so that
they do not warp and leak as they would do on a wooden floor.
' CONNECTING UP OF THE BATHS.
On a large scale when certain duplicate objects are being pro-
duced, a series connection of the bath is to be recommended for
many reasons, because in that manner the production becomes
j more uniform. When connecting in series, there is an assurance
that the cathodes all receive the same amount of metal, will all be
ready at the same time, and must be of similar quality. It is self-
evident that the electrode surfaces in the several baths must be
alike.
If there are considerable differences, however, in the sizes of
the objects when many small pieces are to go into one bath, it is
necessary to use parallel connection of the baths, or regulating
resistances connected up in parallel to each one of the baths which
are in series. These rheostats, in combination with the resistance
of the bath thus provide a nonnal resistance of the cell unit.
A schematic diagram of such plants is shown in Fig. 3. DM is
the dynamo-machine furnishing current, AM is the principal am-
meter. The nine baths are divided into three groups connected
in series, each group consisting of three baths in parallel. Each
series has a regulating resistance RWI, RWII, and RWIII, re-
spectively, connected in parallel.
34
MANUFACTURE OF METALLIC OBJECTS
If, for instance, R is the total resistance of a single bath, Ri
that resistance which exists in a similar bath with a smaller
cathode surface, then it is necessary to put in parallel with this
series a resistance Rg, which in connection with the resistance Ri
will give a normal resistance R.
+ -
Y T
1
. r^V-T
(1
c
1
roxjpc
/
n
■0 O
ro'upe.
i-(
IT
- -
I (
(
>
\
i
c
c
1
c
(
1
>
c
1
»
c
m
• •
1 »
m
^ — r
_
T
T
T
C h
o
s
a
T
Q-
"
i
1
_j
i
*/
7
1-
9 —
>-^
a —
z
JT
"
5—
^ I,
ij —
*~
St—
i
>—
o—
J 1
6
5^
^
1
u
—
y/w,
o
1
— — ^
1
■4-
Fig. 3.
The method of connection must therefore fulfill the condition
expressed by the formula
^ _ Rjj-f-JRj
R, X R2
A voltmeter attached to the ends of the rheostat shows to the
workman whether the adjustment has been properly made, since
the normal current density will be present in the bath when the
voltmeters of the separate baths are alike. If the voltmeter reads
below the normal bath tension, then too great a current is passing
INDUSTRIAL PLANTS 35
through the rheostat and too small a current through the bath
and the latter is working with too small a current density ; in this
case the resistance of the rheostat should be increased until the
voltmeter indicates the normal bath tension.
PARALLEL CONNECTING OF THE BATHS.
When the baths are connected in parallel, the rheostats are con-
nected in series with the baths so that the bath-current goes
through the rheostat. This provides a means of reducing the
voltage of the system down to a normal bath tension or of mak-
ing the bath tension smaller in order to produce a normal ctirrent
density when there are smaller cathode surfaces in the bath, which
disturb the relation between the anode and cathode surfaces.
The regulating resistance then absorbs the voltage V,-v ; that
is, it causes this drop of potential when the bath current passes
through it. Its maximum resistance is therefore :
R (max) ^
A (rain)
Fig. 4 shows this method of connecting used for two baths.
BRi and BR, are the bath-current regulators for the baths R, and
Bj. The voltmeters VMi and VM, are in parallel with the elec-
trodes, a and b are the main conductors, DM the central dynamo,
MW the shunt winding, NR the field regulator, BS the lead fuse,
36 MANUFACTURE OF METALLIC OBJECTS
AM the main ammeter, HA a single pole hand switch, and VU
a voltmeter switch for the voltmeter VM. The voltage of the
system, V, measured by placing the voltmeter switch on the ar-
restment 2, is held constant by the shunt regulator, and the bath
tension is adjusted by the regulator BRi and BRj.
THE CONDUCTORS.
It naturally can not be within the scope of this work to treat of
the calculation of the conductors. I will limit my observations to
what I regard as normal : the drop of potential in the conductors
should not be greater than 7.5 per cent, of the voltage at the
dynamo terminals, whether either parallel or series connection is
used. The plant with series connections necessarily works better
from a financial standpoint because the cross-section of the con-
ductors is much smaller, also the contact surfaces at the joints of
the conductors may be lighter.
On the other hand, the insulation is simpler with parallel con-
necting and therefore in many plants a mixed connection such as
is shown in Fig. 3 has been found most suitable.
Vn. PARTICULAR DEVICES FOR SPECIAL
PURPOSES. PRODUCTION OF UNIFORM
DEPOSITS.
DISTRIBUTION OF CURRENT LINES.
If the current is allowed to pass from an anode of any size to a
smaller cathode, without taking particular precautions, it is often
found that the edges and such parts of the cathode which hang
closer to the anode are more heavily coated with deposit than the
other parts. The explanation of this is as follows: the separate
surface elements of the cathode and those of the anode form in
combination with the corresponding cross-section of the electro-
lyte a total resistance R which is formed of the parallel single re-
sistance elements r. According to Kirchoff, however, the total
current A must distribute itself in proportions corresponding to
the conductivities of the separate resistance elements. With
equal distances between all of the cathode-surface elements and
the corresponding anode-surface elements (assume these elements
I square centimeter each), there will result an equivalence of the
separate resistance elements, giving them the values ;
/ X loo
^'^ kXs
the result being in ohms if / is the distance of the electrode sur-
face elements from each other, in decimetres, k is the conductivity
of the electrolyte per decimetre,' and s is the cross-section (say
one square centimeter) of the conducting fluid.
In case that the anode as well as the cathode form the end sur-
faces of the trough and are parallel to each other and reach to the
surface of the fluid, all the resistance elements in the fluid are
equal. Or if it is possible that there is a certain cross-section of
electrolyte above the edges of the cathode, then current lines di-
verge into this space and concentrate down upon the edges of the
cathode. The consequence is that the sum of these lines
^ / X lOQ
kX s
38
MANUFACTURE OF ME:TALUC OBJECTS
will increase the current density upon the cathode edges, where-
by an inequality of the rate of growth takes place.
The case is similar if projecting parts of the cathode or anode
reduce the length /of the resistance elements. This results in in-
creasing the current density on the electrode surface elements
concerned and increases the influence of electrolysis upon cathode
or anode.
UNIFORM DEPOSITS.
Fletcher^ obtained uniform deposits by rotating the cathode
and arranging the anodes at a certain distance from it. It may be
remarked that Fletcher's method can be improved if the various
distances for the anodes are worked out graphically.
Figs. 5. 6, 7.
Engelhardt^ made the further improvement by eliminating the
errors which could not be avoided by rotating the cathode alone,
by rotating the anode as well as cathode. Thus, by varying at
I American Patent, 485, 343— Lum. El. 1892, 47, 32.
American Patent 544, 668, Aug. 20, 1895. See also Zeitschr. f. Elektrochemie a, 408.
PRODUCTION OF UNIFORM DEPOSITS 39
times the initial velocity of rotation, the average current density
on all parts of both cathode and anode can be kept alike, whereby
a unifomi growth of the deposit and a uniform solution of the
anode would be obtained.
The apparatus proposed by Engelhardt for obtaining these ends
is shown in Figs. 5, 6, and 7.
The contact strips / are placed upon the edge of the decomposi-
tion cell a. Upon these rest the cathode carriers h of non-con-
ducting material having metallic strips m underneath. At right
angles above them are the anode carriers c, which are provided
with the conducting strips k on their upper surface. The elec-
trodes e and g, fastened to rods / and /, are hung to their supports
by the clamps d and so connected with the conductors.
The collars v are movable upon the rods e and g and can be
clamped by screws and so hold the electrodes in the guides d.
The electrodes can be rotated by means of the rope pulleys i and h.
PROCESS OF BAUER.
J. G. Bauer^ patents the following process for the manufacture
of curved bodies which must be precipitated upon moulds having
the corresponding projections.
Patent Claims.
1. A process for the production of uniform galvanic deposits
upon non-conducting bodies, characterized by having metallic
chains inserted into the cores, the links of which appearing at the
surface of the core form points of attachment for the galvanic
precipitate. .
2. The use of the principles of Claim i applied to cast articles
of wax, gypsum, etc., consisting of inserting through these bodies
metal wires provided with heads or enlargements, in such man-
ner that one end of the metal wire appears at the upper surface of
the body while the other end is connected with the main current
conductor.
PROCESS OF ANDERSON.
Anderson^ worked similar to Fletcher, surrounding a rotating
cathode core by anodes arranged around it concentrically as
anode strips.
1 German Patent 65, 819, Feb. 6, 1892.
2 American Patent 534, 942, Feb. 26, 1895.
40 MANUFACTURE OF METALLIC OBJECTS
WUBTTEMBEBG PROCESS.
The superintendent of the Wiirttemberg^ Metal Ware Works
made an important advance in this special line, useful in case that
a non-uniform division of the precipitate was desired, where for
instance certain projecting parts of the finished article were de-
sired to be more thickly coated. This is obtained by placing in
the bath between the article and the anode, plates of insulating*
material, such as glass, etc., which are provided with openings
and result in largely cutting off the current from the parts which
are covered and increasing the current passing to the parts imme-
diately behind the openings, so as to produce at will a non-uniform
distribution of the current.
These plates may be called screens or current-line deflectors^
If the opening in the distributor is for instance circular, then the
current lines form approximately a paraboloid of revolution and
the projection of the latter upon an article gives the desired dis-
tribution upon the cathode. Self-evidently, the projection surface
upon the cathode varies with the distance of the deflector from it
and if the latter is at a great distance, the projection becomes
blurred and disappears.
The process is protected by the following patent claim :
Patent Claim,
Process for the simultaneous obtaining of galvanic metallic de-
posits of varying thickness upon the same object, produced by-
arranging between the latter and the anode freely hanging plates,
of insulating material.
Extension of the Process,
These cleverly designed aids can, as has been proved by the
inventor, be used in order to produce heavy precipitates upon the
deeper lying parts of the mould, in the production of curved ob-
jects : this is done by arranging the perforated shields before the
cathode with the opening so arranged that the resistance capacity
of the elements of the cathode surface at the deeper lying parts is
made equal to that of the other parts of the object.
Figs. 8 and 9 will illustrate this.
1 German Patent 7^. 975, July 30, 1893.
PRODUCTION OF UNIFORM DEPOSITS
41
If the cathode K is hung opposite to the anode A with no special
precautions, then with the electrodes at too small a distance apart,
great differences will occur in the values of the resistance ele-
ments, resulting in excess of current density around the point S.
But if it is desired to coat over the whole spherical surface uni-
formly, then, as is shown in Fig. 9, a shield is placed before the
object in such a manner that the apertures oo;'i are in the position
shown. The course of the current lines will be thus deflected,
until they will distribute themselves nearly uniformly over the
■whole cathode surface.
As long as the condition
fulfiKed for all the
■elements of the cathode surface, the distribution of current-lines
will be equal upon all parts of the cathode, producing a uniform
deposit.
+ — -^
For sharp corners, the division is rather more difificult. The
investigations of the author have shown an analogy between the
path of the current-lines and the distribution of the magnetic
lines of force and has shown that with larger electrode surfaces,
above i square decimeter, and with electrode distances of more
than 5 decimeters, the scattered current-lines will be more than
25 to 30 per cent, of the number of current-lines which would
■exist in a homogeneous field between two plane parallel electrodes.
"The amount of the scattering of the current-lines increases with
the distance of the electrodes apart and decreases with the size of
the electrode surfaces. The following expression will serve to
-approximately indicate the value of the coefficient of scattering,
coef. =
42 MANUFACTURE OF METALLIC OBJECTS
where a is a factor depending on the conductivity and upon the
electrolyte. Only a few very approximate values have so far been
obtained^ for this factor and it can only be- said that in equally
good conducting alkaline or cyanide solutions the coefficient of
scattering of current-lines is greater than in acid solutions.
DUMOUUN PROCESS.
The process of E. Dumoulin^ is somewhat connected with a
screen process. Dumoulin used his process for the production of
objects with surfaces of rotation, basing it on the principle that
inequalities in the surface of the precipitate are caused by un-
equal distribution of the molecules and especially by rough places
upon the cathode. If an unevenness exists upon the cathode either
before the current is started or afterwards, or as a result of the
poor precipitation of the metal resulting from a bad preparation
of the form or by a deposition of the slimy impurities from the
electrolyte, Dumoulin insulates these points of unequal deposit
until the surrounding parts have reached the same thickness.
The process is protected by the following patent claim.
Process for the manufacture of uniform electrolytic metallic
deposits consisting in placing upon the cathode during the pre-
cipitation insulating material; producing this effect in a manner
similar to the inking of type; reintroducing the surface into the
bath wherein the insulating material itself is slowly removed, but
not before the points coated have disappeared and become uni-
form with the whole surface of the cathode.
The Insulating Material,
The materials used for insulation are tar, fat, vaseline, albumen
and the like and the quantity of the insulating material used can
be regulated by the workman in charge, and the growth of the
surrounding deposit is thus regulated. It is clear that the cur-
rent density will have a certain influence on the kind of insulating
material used as well as the frequency with which the application
is made.
The applications of this process are more extensively described
later (see page 125).
» See Zeitschr. f. Elektrochemie 7, 895. Dr. W. Pfanhauser, "Ueber die Strcuung
der Stromlinien in Elektrolytcn."
2 German Patent 84, 834, April 9. 1895; English Patent 16, 360, August 31, 1895.
PRODUCTION OF UNIFORM DEPOSITS 43
METHOD OF THE FRENCH COPPER COMPANY.
The Societe des Cuivres de France^ in 1894 obtained a patent
based on the following principles :
If these conditions which are necessary for the obtaining of uni-
form deposits are not fulfilled, irregularities will necessarily ap-
pear, so that often with the most varied shaped anodes or even
by arrangement of anode strips around the cathode, the irregular-
ities cannot be entirely overcome.
The point referred to consists in surrounding the rotating
cathode with anodes which are provided with projections or in
general with equal "unevennesses." There is thus produced upon
the rotating cathode a corresponding unevenness in the precipi-
tate. The author believes the process to have a very limited* appli-
cation because slight projections on the anodes will soon be dis-
solved off and then will exert no further influence.
Devices for Loosening of the Precipitates.
The precipitates are made upon particular forms, which, if of
non-conducting material such as wax, gutta-percha, plaster of
Paris, etc., must be made conducting by suitable surfaces of con-
ducting material, such as graphite, finely divided silver, etc. Me-
tallic forms are often used which are given an intermediate con-
ducting coat if it is desired to remove the metallic precipitates
upon them ; the coating must be of such a nature that it does not
combine with the metal, and yet does not hinder the conduction
of the current. For such intermediate coatings the sulphides of
the heavy metals may be used, or the metallic surfaces may be
iodized or greased. W. Wood^ proposed the graphitizing of non-
conducting forms by the use of rubber dissolved in linseed oil;
the further description of this is given in the special applications
of galvanoplasty.
PROCESS OF SUTHERLAND.
W. S. Sutherland^ manufactured surface condensers by the
precipitation of metal upon an easily fusible core, which was melt-
ed out at the completion of the precipitation.
1 English Patent 23, 679, Dec. 5, 1894.
2 English Patent Oct. 30, 1873.
* English Patent 8054, May 22, 1884.
44 MANUFACTURE OF METALLIC OBJECTS
PROCESS OF BEINFELD.
A. K. Reinfeld^ had the idea to nickel plate the forms before
using them, being convinced that traces of nickel dissolve in acid
copper sulphate solutions, by which reaction a very small amount
of copper is separated out which does not adhere to the nickel
surface ; so that by further electrolytic precipitation of copper it
was possible to obtain a precipitate not adherent to the form and
easily lifted off.
The loosening of the precipitate is easier if the nickel plated
surface is treated with oxidizing agents or soap-like mixtures.
In the latter case the surface of the form becomes extremely
smooth because this mixture fills up any small unevennesses. The
oxidation of the surface of the form can be produced by potas-
sium chromate, or potassium manganate (the solution should be
concentrated). The forms remain in this solution about 15 min-
utes, and are then washed and rubbed off.
Patent Claim.
The process for manufacturing easil}'- removable metallic pre-^
cipitates electrolytically, consisting in providing a printing plate
of any suitable form with a coating of nickel, or using plates al-^
loyed with nickel, upon which the metallic precipitate is to be pro-
duced ; treating these plates with chromium or manganese salts or
soap-like mixtures for the purpose of making their surfaces per-
fectly smooth, whereby the easy removal of the metallic precipi-
tate is rendered possible and subsequent polishing may be dis-
pensed with.
METHOD OF HOLI.
C. Holl- uses pure nickel as the form material for the remov-
able precipitates. For greater cheapness he proposes to use also*
the following materials: cobalt, copper, steel, lead, cadmium, an-
timony, aluminium, tin ; also ferro-silicon, ferro-chrome, etc. The
materials used can also be supported upon glass in quite thin
sheets and casings. Calcium chloride, also oxygen, either atmos-
pheric or electrolytically produced, as well as other oxidizing sub-
1 German Patent 50,^50, Nov. 2r, 1888.
2 German Patent 7/,sc/, Oct. 7, 1F9?. ?iipf Itmentr.ry to Gein an Fattnt .'o,rco, Ncv
22, 1F&8.
PRODUCTION OF UNIFORM DEPOSITS 45
Stances, render possible a preparation of the fomi in the manner
desired. The main condition is always that the intermediate layer
be insoluble in the electrolyte.
For instance, cuprous chloride, CuCl, can be used in copper
baths for copper cathodes, silver cyanide for silver deposits in
silver baths, or copper forms can be coated with a thin deposit of
silver and the silver coating converted into a compound, with a
non-metal, in order to facilitate the detaching of the subsequently
precipitated copper.
Patent Claims,
1. The process of manufacturing easily removable metallic pre-
cipitates produced galvanically according to German Patent
50,890, by using pure nickel for the printing plate or form in-
stead of a nickel coated or nickel alloyed plate.
2. In the use of the process of German Patent 50,890 and the
process of the above Claim i, the treating of the cathode either
with various oxidizing agents such as chromium and manganese
solutions or also with hydrogen peroxide, ferricyanide of potas-
sium, chloride of lime, atmospheric oxygen, electrolytically pro-
duced oxygen or the precipitation of oxides insoluble in the elec-
trolyte, or by insoluble conducting metallic cyanides, haloids, or
sulphide compounds upon the surface of the cathode whereby the
electrolytic deposition of the metal can be produced, different
from the metal contained in the protecting intermediate coating,
or the metallic surface of the form.
ELMORE'S PROCESS.
The Elmore German and Austro-Hungarian Metal Company^
patented in the year 1891 a method for the production of several
consecutive cylindrical coatings upon a mandril. According to
this process the metal is coated in place with a material which pre-
vents adhesion of the subsequent deposit, such as fat, metallic
sulphides and the like. When a precipitate has been formed en
this the insulating process is repeated. It is thus possible to pro-
duce several layers on the same profile upon each other, and by
cutting loose or otherwise separating from each other, sheets, rib-
bons, etc., are produced.^
1 German Patent 64.420, July 7. 1891 ; English Patent 5,167, March 23, 1891, 14,624, (1890),
11.778, (18S8) ; American Patent 484.704 ; French Patent 214,641.
* Compare also Burgess, Zeitschs. f. Electrochemie, 5, 334-
46 MANUFACTURE OF METALLIC OBJECTS
Patent Claim.
The process of producing several concentric cylindrical metal-
lic precipitates consecutively on a mandril electrolytically, con-
sisting in coating the surface of an already formed galvanic pre-
cipitate with a sulphide, fat or other material preventing the ad-
hesion of a new precipitate and subsequently precipitating a
further galvanic coating upon the one first formed.
NUSSBAUM'S PROCESS.
A novel method of separating precipitates from the forms was
proposed and patented in 1896 by A. Nussbaum.^ The process
itself will be further described at length and I limit myself here
to saying that the easy and satisfactory removal of the precipitate
from the particularly constructed model is obtained by introduc-
ing a fluid under pressure, which raises a valve-like part of the
surface along with the precipitate upon it and so passes between
the surface of the form and the precipitate.
The loosening can also be attained by depositing the metal at a
free space upon the model upon a bolt so arranged that it can be
unscrewed and removed, leaving a tube which serves as a pres-
sure tube for introducing the fluid between the deposit and the
mould.
COLLAPSIBLE FORMS.
The Electro-Metallurgical Company, Limited,^ uses collapsible
forms from which the deposit is easily removed. The forms con-
sist of thin metallic strips rolled in many windings upon each
other. The loosening of the deposit is produced by drawing to-
gether the roll of strips by the assistance of the framework in the
interior, which is gripped by a suitable tool ; that is, the diameter
of the successive rolls of ribbon are diminished and the precipi-
tate becomes loose of itself, even when very long tubes are being
produced.
Because of its elasticity, the form after being removed from the
precipitate takes its original shape and size.
1 German Patent 91,146, May 28, 1896. See also Zeitschrift des osterreischen Ingenieur
und Architekten-Vereins, 1899, 296. Kngrelhardt, " Ueber das Nussbaumsche Ver-
fahren."
« German Patent 89,780, May 24, 1896 ; American Patent 592,802 ; English Patent 11,338,
May 23, 1896.
PRODUCTION OF UNIFORM DEPOSITS
47
Patent Claim.
The cathode for the reception of solid precipitates made elastic
and spirally-formed so as to permit being rolled together and thus
loosened from the precipitate and which in consequence "of its elas-
ticity retakes its original form.
ELMORE'S PROCESS.
The Elmore German and Austro-Hungarian Metal Company^
produces objects electrolytically, and uses as means of separating
them from the mandril on which they are precipitated, the follow-
ing process.
The thin metallic tubes which serve as mandrils for the precipi-
tation are coated over with a material fusible at a low tempera-
ture and made smooth.
Apparatus,
The mandril a, in Fig. lo, is with its axle a^ laid in a socket
b of the frame c. The projecting part of the frame has a slit d in
Fig. 10.
which are two boxes e adjustable by the spindle f. In the boxes
rest the spindle of the roll g lying parallel to the mandril. This
roll g can be so adjusted by the spindle / that it forms a wedge-
shaped gutter with the mandril a, into which by means of the
hopper-shaped vessel h, the material is fed which shall be used
to coat over the mandril. The spindle a^ of the mandril a is liol-
1 German Patent 63,838, April 12, 1891 : English Patent 7.932. May 22, 1900 ; American
Patent 485,919 ; French Patent 212,385.
48 MANUI^ACTURIt OF MB^TALUC OBJECTS
low and serves for the introduction and circulation of cold water ;
on the other hand, either hot air or steam is led through the roll
g, the whole arrangement to keep the mandril cool and the roll
warm. The coating material coming out of the funnel h is melt-
ed by the heat of the roll g and sets upon the cold mandril a. The
thickness of the layer produced is regulated by the adjustment
of the roll g. The coating may be either of an easily fusible
metallic alloy or of some wax-like material. In the latter case,
when non-conducting substances are brought upon the mandril, it
is necessary to puncture the coating in numerous places through
to the metallic surface of the mandril ; or to effect this, to add to
the coating material some salt easily soluble in water which can
be washed out of the coating by immersion in water before plac-
ing in the electrolyte and thereby producing the desired porosity
of the coating. The coating material can also be mixed with
graphite.
When the electrolytically produced tube has been deposited
upon the mandril the whole is warmed, as for instance, by intro-
ducing hot water into the interior of the mandril and so melting
the coating upon it. The metal shell can then be easily removed
from the mandril.
Patent Claims.
1. The process of facilitating the loosening of electrolytically
produced deposits from a tubular mandril consisting in giving to
the latter an easily fusible or smooth coating, soluble in a fluid,
by the use of a rotating smoothing roll ; in case the coating is non-
conducting, providing it with numerous small holes, or mixing
with it a conducting powder or a powder soluble in the galvanic
bath, in order to produce a conducting path between the mandril
and the conducting surface, such as graphite placed upon the non-
conducting coating.
2. In the application of the process of Claim i, in the case of
using a coating soluble in a fluid the use of a tubular mandril
provided with numerous perforations which are kept closed until
the finishing of the perforated tube and which are afterwards
used to facilitate the solution of the coating in a short time.
PRODUCTION OF UNIFORM DEPOSITS 49
The Best Material for Coatings.
P. E. Preschlin^ in connection with the Elmore German and
Austro-Hungarian Metal Company patents as particularly ad-
vantageous, the filling of the tubular mandril with cold water in
order to freeze immediately the coating placed upon it. The tube
is first painted with asphalt varnish which produces a good ad-
liesion of the coating. The latter consists of
Paraffin wax 75 parts
Pitch 25 "
This melts at 63° C. It is either poured upon the mandril or the
cooled mandril is rotated while dipping into the melted material.
AVhen the coating has set, it is turned off smooth by the use of a
strong jet of water. In this manner not only cylindrical tubes,
"but all types possessing a surface of revolution, and even helical
.•surfaces can be made.
Patent Claim.
In the use of the process of patent 63,838 the production of an
easily fusible coating upon a mandril by painting the latter with
asphalt varnish and then giving it a coating of a mixture of wax
and pitch with simultaneous cooling of its interior.
COLLAPSIBLE MOULDS OF aERHARDI & CO.
German Patent 123,056, of December 13, 1900, of the firm
of Gerhardi & Co., of Liidenscheid,^ is identical with the Stein-
weg process and recalls that of the Electro-Metallurgical Com-
pany, Limited. It is concerned with the manufacture of easily de-
tachable galvanic precipitates and especially with the manufacture
♦of nickel vessels.
Objects of Pure Nickel.
The previous processes for the separating of galvanic precipi-
tates from their matrices are very little suited in many cases for
nickel deposits ; in some cases quite impracticable, especially whea
the precipitate is made upon a surface which is not quite even or
aipon a grooved or recessed matrix.
In depositing nickel the ordinarily used matrices of wax, rub-
l<German Patent 72,195, April 6, 1893.
-* Eugliiih Paient 13,365, 1901, and German Patent. March 17, 1901
50 manui'acture: o^ metallic objects
ber, gum arable, and similar materials made superficially conduct-
ing, are impracticable since heavy deposits in a reasonable time
can only be obtained in hot solutions in which the materials named
above would become soft and lose their form.
The process of making the forms out of easily fusible metal
and melting the latter out after the formation of the deposit has
the great disadvantage of always forming an alloy with the first
precipitated part of the deposit.
It is only possible in depositing nickel to use matrices of hard
metal such as brass, copper or iron. Using such materials, only
simple shaped flat objects or smooth hollow objects like cylindri-
cal and conical objects can be made, or such as allow the removal
of the core either by the contraction of the same or by the ex-
panding of the precipitate by means of rolling, hammering, water
pressure, etc.
The process is, on the other hand, not applicable for all other
objects; that is, for the production of hollow vessels with con-
stricted openings, recesses or off-sets or ornamental decorations.
Process,
The process to be described allows of the production of articles
of any form whatever, and in particular, of hollow vessels of al-
most any desired form and with raised or recessed surfaces. The
manner of working is characterized by the use of thin walled hol-
low metallic matrices made out of soft easily torn metals ; for in-
stance, of alloys of tin, zinc, or lead with antimony, bismuth, cad-
mium, arsenic, mercury, etc., the brittleness of which is increased
when the temperature is made very low (using tin or tin-antimony
alloys), or when the temperature is raised (as with tin, lead or
bismuth alloys) ; and the side which does not receive the precipi-
tate is provided with grooves or small linear recesses. The grooves
which reach nearly through to the other surface divide the walls
into strips or divisions. After the formation of the precipitate,
the single strips are lifted and torn away by the aid of suitable
tools. By properly dividing up the walls of the matrices in this
manner, cores of almost any shape whatever are easily removed
without changing the form of the precipitate.
The carrying out of the process may be varied in separate
PRODUCTION OF UNIFORM DEPOSITS 5 1
cases. The material for the matrices is lead, tin, or an alloy, such
as Britannia metal, as best suited to the purpose.
If the matrix is made of sheet metal, the sheet may be previous-
ly passed between rolls, one of which is smooth and the other pro-
vided with grooves and projections or the plate is laid upon a
steel plate provided with corresponding projections, and the two
passed together between two smooth rolls. With cast matrices,
these grooves may be easily produced by providing the part of the
mould which is back of the matrix with corresponding ribs or
projections or the corrugations may be made by cutting by a
suitable tool upon a lathe, a planing or a milling machine, or final-
ly done by hand. In this case care must be taken that the tool
does not cut too deeply so as not to damage the other side of the
matrix.
The cuts or grooves can be made either before or after the for-
mation of the precipitate. The direction of the grooves is pre-
ferably so ordered that the walls of the matrix are divided into
single parallel strips which can easily be* torn away. With ob-
jects of revolution it is often practicable to produce the grooves
spirally so that the whole wall of the form can be rolled off in a
single helicoidal strip. With complex matrices a further sub-
division of the walls must sometimes be made.^
1 See also Zcitschr. f. Elektrochemic, 8, 193.
Vra. MANUFACTURE OF METALLIC POW-
DERS AND THE LIKE.
In order to produce directly metallic powders electrolytically
there are two methods. It may be separated out cathodically from
such solutions which do no furnish coherent precipitates, or it
may be separated out of a normal metallic bath by precipitation
upon a powdered cathode. The latter method must really be in-
cluded in the art of galvanoplasty since it concerns a superficial
coating of a conducting substance.
PRINCIPLE'S.
If powder is to be separated directly from a solution of metallic
salt, dilute solutions are used or such additions are made to the-
electrolyte as experience has shown will cause the separation of
the metal in the form of a powder. Such additions may be, for in-
stance, solutions of such metals which are more electropositive
than the metal to be precipitated or a corresponding quantity of
free acid.
LEAD POWDKR.
A fine crystalline powder of lead can be obtained from a solu-
tion of lead nitrate containing 50 grams of lead nitrate per liter
if care is taken to keep the current density above one ampere per
square decimeter of depositing surface. It is also important that
the electrolyte be actively stirred, otherwise layers of solution
rich in metal form at the bottom of the vessel from which lead is
precipitated in another form.
COPPER POWDER.
A strongly acid, quite dilute soltion of copper sulphate furnish-
ed copper in the form of a fine powder. The Elektrizitats-Aktien-
gesellschaft, formerly Schuckert & Company,^ produce in this
manner, and afterwards still further pulverize the powder accord-
ing to the German Patent, No. 88,415, of August 15, 1896.
1 German Patent 88,273, Aug. 24, 1S94 ; Peters " Elektroraetallurgie und Galvanoplas-
tik, ' I, 47 et seq, and Zeiischr. f. Rlektrochemie, 3, 199.
MANUFACTURE OF METALLIC POWDERS 53
Principle.
The primary condition is that a crystalline deposit always falls
if compounds of higher valence are present in the electrolyte,
which by reduction to lower valence, partly redissolve the metal
precipitated.
Example,
Tin may ht obtained as a fine powder if ferric chloride or ferric
sulphate is added to the electrolyte along with small quantities of
organic acids. The metal of these solutions added should not be
precipitated by the current, which is easily effected by keeping the
solutions correspondingly acid or alkaline according to the kind
of metal in the solution added. Copper powder may be precipi-
tated from cuprous chloride solutions if cupric chloride or ferric
chloride is added continuously during the electrolysis.
In case that the metallic salt added is only raised to the higher
state of oxidation during electrolysis, the current density at the
anode is so regulated that as the anode is being dissolved some of
the added salt is simultaneously somewhat oxidized or perduced.
Process.
The baths used are worked with an average tension of 0.8
volt and a current density of 220 amperes per square meter, the
distance betwen the electrodes 10 centimeters. The solution is
kept at room temperature and agitated by a stirring apparatus.
When making a loosely crystalline mass of metallic copper, there
are used anodes of cast copper 20 millimeters thick and cathodes
of sheet copper i millimeter thick.
Uses.
According to the Austrian Schuckert Works, this product is
capable of replacing bronze powder made in the ordinary way.
Although the product is quantitatively satisfactory, it is, however,
too heavy to compete with the ordinary bronzes. On this ground,
no plant has been erected for the carrying out of the operation.
Patent Claim.
The process for the production of loosely coherent crystalline
metallic masses suitable for the manufacture of metallic scales or
54 MANUFACTURE OF METALLIC OBJECTS
bronze powder, electroljticall}', consisting in using as electrolyte
solutions containing the metal to be precipitated and also other
metals which are not to be precipitated and which are in the high-
er state of oxidation, and which are able to redissolve the pre-
cipitating metal forming its lower salts ; the anode being soluble
and of the same material as that being precipitated, and no dia-
phragm being used in the process,
PEOCESS OF THE SOCIETE CIVILE.
The Societe' civile d'etudes du Syndicat de I'acier Gerard sub-
jects the metal to the action of the current while in the molten
condition and in a thin freely falling column using high current
densities and small tensions.
Applications.
The process is suitable for the manufacture of metallic powders
and also as an intermediate step in a process having for its object
the subdivision of materia! without reference to its state of
comminution or the final condition. The first use is illustrated by
the production of lead powder for accumulator plates. The second
method of application may be illustrated by the treatment of a
finely divided stream of fluid iron with an excess of air for the
production of steel.
The apparatus used is shown in Fig. ii,
1 GemiBD Patent 69.061, Dec. 14, 1695 ; see also Zeitrehrift f. Elektrochemie, 3, '37-
MANU^ACTURIS OF METALLIC POWDERS 55
The melted metal is in the vessel a, in the upper part of the
shaft ^ terminating below in the vertical middle plane of the shaft
in a slit-like opening a^. At some distance below the latter the
electrodes ee, most suitably of carbon, project through the walls
of the shaft, leaving between their parallel sides an opening cor-
responding to the above mentioned slit. The metal falls in a thin
layer between the electrodes ee, is thereby finely divided by the
current, its temperature is raised, and it falls as a rain Wg in the
lower part of the shaft where it collects as a powder or dust ac-
cording to whether the particles fall a long distance, or the bot-
tom of the shaft is artificially cooled, or the arrangement of a re-
ceiving fluid which may be placed in the bottom of the shaft, or
a current of ascending gas which may be projected against it.
In case the transformation to powder or dust is only an in-
termediate step in the production of the material, in order to
allow of the better action of a vaporized or gaseous reagent, for
instance such as the steel manufacturing process mentioned above,
the shaft may be provided at the proper distance below the elec-
trodes with tuyeres for the introduction of the reagents; and
higher up and closer to the electrodes, with openings d for the
exit of the same or of the gaseous products resulting. ( See Fig.
II, right hand side).
PROCESS OF HOEPFNER.
L. Hopfner^ obtains loose metallic masses in coherent flat
plates. He first precipitates from the solution which may be of
normal composition a pulverized or moss-like branching metallic
mass by using high current density and for a period of 15 to 30
minutes, and then somewhat stiffens this by using a smaller cur-
rent density for several hours and coats them with a coherent me-
tallic plating.
Porous Copper.
In order to make porous copper, the ordinary acid copper bath
used in galvarioplasty can be employed. Starting with a high
current density of same, 4 amperes per square decimeter, powder-
ed copper is as is well-known obtained; this is followed by a
1 German Patent 87,430, May 11, 1895; English Patent 17,671, Aug. 10, 1896; see also
. Zeitschrift f. Elektrochemie, 3, 130.
56 MANUFACTURE OF METALLIC OBJECTS
smaller current density, which is continued until the dark color of
the powdered precipitate is changed into the well-known bright
red color of electrolytic copper. If it is wished to work entirely
with small current densities, a solution is used which contains less
copper and more sulphuric acid.
Porous Lead.
Lead can be similarly obtained, but it is better to throw down
the lead not in the state of powder, but in the form of leafy or
moss-like crystals. The suitable current density for obtaining
these leaves may vary between that which produces spongy lead
and that which produces dense lead. This current is allowed to
run for some time, then the current density is decreased some-
what in order to make the small leaves which are at first some-
what delicate more resistant. The regulating of the current den-
sity (from the stronger to the feebler) can be automatically ad-
justed by using at first a current density only a little greater than
that necessary to deposit metallic powder or leafy lead; as soon
as a certain quantity of metal has thus separated, the total cathode
surface in contact with the electrolyte being increased, the new
surface receives deposit with a lower current density, if the total
current has been kept constant. For the production of the subse-
quent layers of metal successively higher current densities must
be used. It is to be recommended to exert a small pressure upon
the mass of leaf-like lead by means of a smooth surface, in order
to reduce any large cavities and to obtain a uniform porous de-
posit. Not all lead solutions are equally well suited for the ob-
taining of such leaf-like lead. A solution of nitrate of lead gives
for instance hard leaves which become brittle when pressed to-
gether, while a solution of lead oxide in caustic soda or caustic
potash yields very soft and flexible leaves.
Patent Claims.
1. The process for the electrolytic production of metals in the
state of a porous but coherent precipitate, characterized by the
consecutive use of difl'ering current densities by which a pow-
dery or leaf-like or branching-mossy form of metal is first pre-
cipitated and afterwards dense metal.
2. In the process of Claim i, the automatic regulation of the
MANUFACTURE OF 'METALLIC POWDERS 57
current density by the use of an original current density only
slightly above the limit of that which furnishes dense metal.
3. In the production of the leaf-like structure of metals as
claimed in the process above described, the compressing of the
electrolytically produced metallic leaves by a gentle mechanical
pressure not sufficient to affect the porosity, used alternately with
the application of the current.
4. In the process of Claims i, 2 and 3, the use of a solution of
lead oxide in caustic alkali as an electrolvte.
Modification of the Process,
Instead of changing the current density and using the same
concentration of solution the former may be kept constant and
the latter changed,^ or to increase the effect both factors may be
changed at once ; for instance, a loose form of metal obtained by
the use of a high current density and a low concentration of the
electrolyte, and for producing dense metal high concentration
with a suitable current density. Increasing the temperature acts
upon the electrolyte in the same way as increasing the concentra-
tion. The best work is done in general by using for the deposition
of loose metal the high current density at a low temperature and
with a small concentration of the bath ; and for dense metal higher
temperatures, greater concentration and a suitable current den-
sity. Agitation of the electrolyte at the cathode or movement of
the cathode itself acts similarly to increase of concentration or of
temperature ; agitation of the electrolyte permits of the deposition
of dense metal.
Agitation acts therefore like concentration, particularly since
it equalizes the dilution at the cathode because of the deposition
of the metal from the solution. Its action is particularly to be
noted when the electrolyte is agitated in order to reduce the polar-
ization at the anode. Finally under quite similar conditions a
change in the metallic deposit may be attained by putting the
cathodes alternately into baths of qualitatively different composi-
tion ; for instance, in the production of porous copper alternately
in baths which are neutral or acidified by sulphuric acid, or for
increasing these effects a change in the qualitative composition of
i German Patent 89,289, Jan. 1, 1896 ; Addition to German Patent, 87.430.
58 MANUFACTURE OF METALLIC OBJECTS
the bath may be coupled with changes in the current density, con-
centration, temperature or by decreasing agitation so that there is
obtained first loose and then dense metal. To carry out regularly
the alternations of the conditions named two different systems
may be advanced, either the use of two separate cells and two
separate electrolytes in which the cathodes are alternately plunged
or working always in the same cell by changing the current den-
sity, temperature and agitation as well as also circulating through
it fluids of differing concentrations and differing compositions.
It is recommended to combine both systems so that the loose de-
posit is treated in one cell first with a somewhat lower current
density or slightly raised temperature until it becomes so strong
that it will bear transporting to another cell where it will be still
further strengthened. Since the surface of the cathode contin-
ually increases during the electrolytic process, a change from
loose to dense metallic deposit can be allowed to proceed auto-
matically if the conditions for obtaining the loose metal deposit are
arranged at the beginning, as near as possible to the conditions
necessary for the formation of dense metal. Now with a change
of current strength, the change in temperature is particularly ad-
vantageous for the automatic regulation for the change in struc-
ture in the metallic deposit. It is to be recommended to particu-
larly use a gentle pressure not injurious to the porosity of the
metal. The process of patent 87,430 may be cheapened by the
additional means proposed, namely of using agitation of the elec-
trolyte and higher temperatures thereby producing also a very
active depolarization of the anode. In fact, in for example, the
separation of lead from not too dilute solutions of lead oxide in
caustic alkalies, the anode remains permanently a metallic white,
even with current densities of 200 amperes per square meter if
high temperatures are used. Using high temperatures, the refin-
ing of the metal is much facilitated and cheapened since in conse-
quence of the smaller bath tension the less electropositive metals
do not go into solution. On the other hand, low temperatures are
suited for the production of insoluble oxides and peroxides upon
the anode. For example, extensive investigations down at a tem-
perature of 9° C. showed that the anodes coat themselves over
MANUI^ACTURE OF METALLIC POWDERS 59
with undissolved or insoluble oxides more quickly the lower the
temperature.
Patent Claims.
Hopfner protects his process by the following comprehensive
claims.
1 . The method of carrying out the process of patent 87,430 for
the electrolytic production of metals in the from of porous, yet
coherent precipitates, characterized a) by alternate application of
two solutions of different concentrations and such changes of the
suitable current density in each case that at one concentration
loose metal, at the other concentration, dense metal is precipi-
tated; or b) by the alternate application of two different tempera-
tures of the electrolyte and such changes of the corresponding
current density that at one temperature loose and at the other tem-
perature dense metal precipitates; or c) by the alternate applica-
tion of rest and motion to the cathode or to the fluid at the cathode
and such changes of the corresponding current density that in the
one case loose metal and in the other case dense metal is obtained ;
or d) by the alternate application of two differently constituted
baths and such changes of the current density that in the one bath
the precipitated metal is loose and in the other is of a dense struc-
ture; or e) by the alternate application of two of the above de-
scribed combinations included under the headings a) to d), and
using suitable current densities so that with one combination loose
metal and with the other combination dense metal is precipitated.
2. For the application of the process of Claim i, a) to e) the
separate and combined application of the two following systems ;
a) the alternate introduction of the cathode into separate cells in
which the arrangements according to Claim i, a) to e) are so
adjusted that the cathode in the one cell is coated wuth loosely co-
herent metal and in the other with dense metal; b) the maintain-
ing of the cathodes in the same cell in which, however, the current
density, temperature, agitation or the presence of different elec-
trolytes (the latter by circulation) are made to regularly alter-
nate.
3. In the process of Claim 1, a) to e) the automatic regulation
of the passage of the loose metal into the dense metal by the suit-
6o MANUFACTURE OF METALLIC OBJECTS
able utilization of the automatically increasing surface of the ca-
thode and the diminution of the current density produced thereby.
4. In the process of Claim i, a) to e) and 2, b) : the use of ar-
rangements for the automatic regulation of the temperature and
the current strength.
5. In the process of Claims i to 4, the application of a gentle
pressure not injurious to the porosity of the metallic precipitate,
used alternately with the action of the current.
6. In the process of Claims i to 5, the application of a solution
of lead oxide in a caustic alkali as an electrolyte.
7. In the electrolysis of dilute metallic compounds according to
the processes described in Claim i, a) to e), the use of impure
metal as anodes for the purpose of refining it and the utilization
of the oxides formed at the anode for the obtaining of by-pro-
ducts.
FBOCESS OF HUBER AND SACHS.
Huber and J. Sachs^ produce metallic or metallized powder as a
substitute for metallic and bronze colors, by precipitating the de-
sired metal upon a core consisting of a conductor of the first
class. The powdered cathode to be coated is agitated in the bot-
tom of the electrolytic vessel in contact with a solid cathode con-
ductor so that an intimate contact of the powder with the cathode
conductor is assured with a continuously changing position of the
particles. The anodes are parallel to the cathode plate and are
separated from them by a clay diaphragm in order to avoid" short
circuits between the anode and the powdered metal in suspension.
Patent Claim,
The process for the manufacture of metallic powder consisting
in the electrolytic formation of a metallic coating upon a conduct-
ing powder which is kept in motion in a bath in such a manner as
to be in contact with the cathode while contact with the anode is
prevented by means of a diaphragm.
1 German Patent 79,896, June 27, 1894; American Patent 521,991 and 521.992, June 26,
1894; American Patent 522,415, July 3, 1894.
IX. MANUFACTURE OF METALLIC FOIL.
In order to produce metallic foil or thin sheets electrolytically,
particularly prepared cathode sheets are usually hung opposite to
anodes of the metal to be precipitated in a suitable electrolyte and
left there until the desired thickness is reached.
PROCESS OF REINFELD.
A. K. Reinfeld^ pastes paper upon the thin copper sheet pro-
•duced in the above manner and tears it away from its support.
Reinfeld uses as cathode nickel-plated sheets which have been
treated with oxidizing agents or soap-like materials in order to
prevent the adhesion of the copper skin. In this manner prepared
sheets of only i to 2 thousandths of a millimeter thickness are ob-
tained.
Operation.
The well-nickeled and polished cathode is allowed to stand a
-quarter of an hour in a concentrated solution of potassium chro-
mate or potassium manganate and is then rubbed off. The plates
are covered on both sides with metal and the foil is obtained from
the cathodes with a polish.
PBOCESS OF ENDRUWEIT.
C. Endruweit^ makes copper and nickel foil by titrating the
metal plate serving as a form with a concentrated solution of an
alkaline sulphide, and after washing off with water dips it in di-
lute caustic soda solution. It is then again washed off and placed
in the metal bath. Under some circumstances, it is recommended
to have the plates connected as cathodes with a source of current
when they are dipped into the caustic soda solution.
Patent Claims.
I. The process for the preparation of metallic plates upon
which an insoluble skin of metal is to be precipitated in order to
1 English Patent 3.222, Feb. 22, 1889.
« Bnglish Patent 2.724, Feb. 7, 1893 ; German Patent 82,664, Jan. 25, 1895. See also
Jahrbuch, a, 194.
62
MANUFACTURE OF METALUC OBJECTS
manufacture metallic paper, consisting in treating the plate first
with a solution of alkaline sulphide in water and immediately af-
terwards with a solution of caustic alkali.
Pig. 12.
2. A special method of carrying out the process of Claim i,
especially suitable for plates upon which a skin of copper is to be
MANUFACTURE OF METALLIC FOIL 63
precipitated, consisting in connecting the plates as negative elec-
trodes short-circuited to suitable anodes while being dipped in the
caustic alkali solution.
Improvements.
Endruweit has arranged the process in such manner^ as not to
use a metallic plate as cathode but an endless metallic band (see
Fig. 12).
The metallic band M passes in series through the roll R, the
polishing roll P, passes then into the vessel G in which it is pre-
pared by a 5 per cent, solution of alkaline sulphide. It then passes
into the cleaning arrangement A, and thence into the nickeling
bath Ni, where a thin film of nickel is deposited upon it, which
as has already been explained, serves very well as an intermedi-
ate deposit. The copper bath Cu must self -evidently be of larger
dimensions because the real precipitate is there given. Past the
bath Cu there is a washing arrangement which frees the precipi-
tate from electrolyte coming over from the last bath.
The backing paper which is rolled off from the spool Pj by
means of rollers is supplied continuously with the necessary paste
from the holder K which distributes paste upon the precipitate.
The pasted metallic band passes now to a steam drying apparatus
D, and afterwards the finished metallic paper is stripped from the
metallic band by a sharp instrument and rolled up upon Pg.
ELMORE'S PROCESS.
Elmore's process of producing metallic sheets electrolytically
by the production of a non-metallic intermediate coating has been
already described on page 47 and is merely referred to here.
DESSOLLE'S PROCESS.
L. E. Dessolle^ produces lead metal and all kinds of useful ob-
jects which are to be obtained polished from the moulds, by satu-
rating the surface of the metallic form with hydrogen. The form
is first provided with a coating which is indifferent towards the
electrolyte, and which is not quite removed by the hydrogen.
Acids or alkalies may be used as electrolyte and anodes which are
1 American Patent 676.357 ; see also Zeitschr. f. Elektrochemie, 8, 99.
> German Patent 98,468, Aug. 12, 1897. See Jahrbuch, 6, 333.
64 MANUFACTURE OF METALLIC OBJECTS
insoluble in the electrolyte. A voltage of 2.5 to 3 volts is used anct
the preparing operation lasts up to three hours.
Patent Claim.
The process for the preparation of cathodes for the immediate
production of polished metallic sheets or other objects electrolyti-
cally, by placing upon the cathode a coating not soluble in the
electrolytic bath, then saturating this coating in the electrolytic
bath described with hydrogen and then polishing.
PROCESS OF COWPER-COLES.
The process similar to that of Elmore (see page 45) was
patented by Cowper-Coles in England in 1899, No. 16,210. The
latter produces several concentric layers upon each other, and
uses as an intermediate coating in order to facilitate detaching
the deposit, an alcoholic solution of wax or a layer of metallic
oxides or sulphides. The layer of oxide is obtained by heating in
a mixture of air and steam, the sulphide layer by dipping into-
potassium sulphide. Cylindrical brass forms are used as cathodes
which are rotated mechanically at a surface speed of 1,000 feet
per minute. The precipitate comes down in this manner bright
and coherent, although quite extraordinary current densities are
used.
After several superimposed metallic sheets have been deposited,,
separated from each other by layers of wax or metallic sulphides,
the whole is cut through parallel to the axis of the cylinder and
the metallic sheets are separated from each other. The copper
foil thus produced is used especially for making dynamo brushes.
PROCESS OF LANDAUER & CO.
As an example of one of the processes which are used on a large
scale for the manufacture of metallic paper, that of Landauer^
may be described. In Landauer & Company's Galvanic Metal
Paper Works in Vienna there is manufactured paper pasted to-
copper foil or nickel plated copper foil, as also other similar
manufactures which are protected by a number of patents.
Among the latter may be mentioned copper brushes for dynamos,
coppered asbestos gaskets, flanged gaskets consisting of asbestos
with a loose copper coating, etc.
1 English Patent I5,573. July 15. 1898.
MANUFACTURE OF METALLIC FOIL 65
Principle.
earthen-ware i meter long, 50 centimeters wide and 70 centi-
Landauer precipitates copper, or first nickel, and afterwards
copper, upon highly reflecting polished plates of brass or German
silver, which have been first provided with the already described
detachable intermediate layer; the metallic precipitate is dried,
and then detached by itself. or after being glued to paper.
Baths Used,
The baths used for precipitating the copper have the usual com-
position :
Water i liter
Crystallized copper sulphate 200 grams
Concentrated sulphuric acid 30 "
For anodes there are used electrolytically deposited copper
plates, 500x500 millimetres and 8-10 millimetres thick.
The precipitates must be prefectly smooth and free from pro-
tuberances. To this end, the electrolyte is continuously circulated
and while circulating, passed through a filtration apparatus in the
form of a small filter press so that it is always free from sus-
pended solid impurities. The single baths are connected in series,
the cathode plates of each bath in parallel. In each bath there
are four anodes and three cathodes and between them moves a
mechanical stirring apparatus provided wuth glass rods. The ten-
sion across the bath is only one volt with the electrodes about 10
centimeters apart, and a current density of about 10 amperes per
square decimeter is used.
The dimensions of the lead lined wooden tanks are 700 milli-
meters long, 500 millimeters wide and 700 millimeters deep. If
nickel metallic paper is to be produced, a plate prepared as before,
is given a thin film of nickel precipitate in the following bath :
Water i litre
Nickel sulphate, NiS04 80 grams
Ammonium chloride, NH4CI 20
Boracic Acid, HjBO;, 10
The nickel deposit requires about one minute, a current density
of about 0.5 ampere. The bath tension is 2.3 volts with the elec-
trodes 10 centimetres apart. The tanks for the nickel baths are of
3
tt
66 MANUFACTURE OF METAU.IC OBJECTS
meters deep, and have supports and clamps for one cathode and
two anodes. The anodes are of rolled and of cast nickel sheets
mixed in equal numbers.
Operation.
The German silver plates, 400x500 millimeters are maintained
with a highly lustrous polish in order that the metallic leaves may
have a similar lustre and may be most easily detached. In the
plant in question there are used for this process three polishing
motors of 2j4 H.P. each, driven by a single generator. For pol-
ishing there is used a composition of grease and lime. After pol-
ishing, the plates are freed from grease by lime water and pass
then to the oxidizing or sulphiding baths. The time of this opera
tion is about 5 minutes. After careful washing with water they
are placed in the baths. They remain about 30 minutes in the
copper baths, which are arranged in series of 30, there being two
such series. Each series is run by a motor-generator furnishing
125 amperes at 35 volts. The operation is uninterrupted since for
every plate taken out of the bath a new one is immediately in-
serted in order to avoid irregularity in the current-density rela-
tions. The coppered plates are given another washing and then
placed in a drying room to remove the last traces of moisture,
and then passed to pressing rolls where the paste is fed to them
from a holder, the pasted surface covered with paper and then tlie
plate and paper pass together through two pressure rolls. The
pasted plate is again dried and the metallic paper then detached
by loosening the edges with a knife-like instrument.
Gaskets.
If copper foil is to be made which is not to be pasted on paper,
the copper precipitate is made somewhat heavier, the time of depo-
sition being lengthened to 45 minutes, using the same current
density as before. The flanged gaskets, that is, metallic copper
gaskets with asbestos filling, are manufactured on a large scale
in the works in question and have the following advantages. They
are extraordinarily soft and possess in consequence of their tough
elastic copper coating an extraordinary capability of making a
tight joint, thus utilizing to the greatest extent the yielding qual-
MANUFACTURE OF METALLIC FOIL
67
ity of the asbestos. In this manner the asbestos filling is protect-
ed against the strong decomposing action of the steam, condenser
or cooling water, etc., being protected by the seamless copper
coating closed on the inside.
. *. . • • •
' ' ^
O^
Fig. 13.
a is the asbestos filling, b the copper coating. In consequence
of the continuous metallic surface of the ring, the burning fast
of the gasket surfaces is prevented and the asbestos filling is
therefore capable of being used over many times. The gaskets
are manufactured by the quick electrolytic plating process devis-
ed by the author, the dynamo furnishing a thousand amperes at 6
volts, and driven by a separate electric motor, furnishing current
for a 3,000 liter bath. The electrolyte is kept in oscillation by a
compressor ;^ a tank has 9 cathodes and 10 anodes in parallel. The
thickness of the precipitate is controlled by ammeters attached to
each cathode conductor so that the bath is run independently of
the size of the various electrodes. The thickness of the copper de-
posit is brought to o.i or 0.2 of a millimeter, the duration of the
process, depending upon the current density used, is 15 hours for
a current density of 6 amperes per square decimeter (see the cor-
responding table).
1 See Pfanhauser " Elektroplatierung, Galvanoplastik und Metalpolierung," 4th Ed,,
1900. *
68 MANUFACTURE OF MICTALUC OBJECTS
Brass rings are used as cathodes which are nickeled and pro-
vided with an intennediate stratum similar to that used in the
plates for the manufacture of the metallic paper. The rings are as
thick as the asbestos filling for which the copper coating is to be
made ; mostly 5 millimeters. The copper precipitates are loosened
with a spatula-like instrument, the skill of the workman being an
important factor in this work.
Power Plant,
As a source of power there is a 50 HP. steam engine furnishing
regularly 35 HP., a dynamo attached to the machine gives current
for the whole of the electrical power required. The plant has a
total floor surface of some 600 square meters (6,600 square feet),
and produces daily 3,000 sheets of metallic paper and 2,000 gasket
rings and employs normally 60 hands. The copper used per year
amounts to about 30 tons. The capital of the firm is $70,000.
Costs and Profits,
The firm of Landauer & Company have most kindly, communi-
cated to me their balance sheets of costs and profits, which I am
permitted by them to reproduce here.
DA11.Y Operating Expenses.
•^oo H.P.-hours at I Vc I 3 75
100 kilograms of electrolytic copper 30 00
60 workmen at loc. per hour 60 00
Superintendent at |i,ooo per year 3 37
jo% sinking fund on capital 23 75
5% interest on the capital 1 1 87
40% Government tax on wages 24 00
Unforseen 5 75
Total I162 50
Daily Output.
3,000 sheets of metallic paper at I90 per i ,000 .... $270 00
2,000 Gaskets at I300 per 1,000 600 00
I870 00
30% discount for the trade I261 00
Producing cost 162 50
I423 50
•
Daily profits I446 50
The process of Landauer is carried on in Vienna by the Gal-
vanic Metal Paper Works, formerly Landauer & Company; this
firm also grants licenses for production in all other countries.
MANUI^ACTURE OF METALUC FOIL
69
LEAF SILVER AND LEAF GOLD.
The manufacture of leaf silver and leaf gold is quite easily
accomplished by the principle of removable electrolytic coatings.
From the many patents on this subject I select for mention those
of Wood/ Perner,^ and Brandt & Nawrocki.*
FBOCESS OF BBANDT & NAWROCEI.
This process uses copper plates as cathodes, and for avoiding
the adherence of the precipitate there is used a thin intermediate
layer of wax applied as a solution of wax in alcohol.
Where neutral or potassium cyanide solutions are customary as
for gold, silver, nickel, brass, etc., a solution of rosin in benzole
has been proposed. But for copper which is separated out of a
strongly sulphuric acid solution, a coating of wax dissolved in
alcohol of a strength of i in 50 is applied. The baths used are
the usual galvanoplastic baths the composition of which can be
found in special works on electro-plating.
Time of Deposition.
The time fof depositing leaf gold and leaf silver is given in the
following table :
Metal.
Silver
Gold -
L
Thickness
of the
metal leaves
mm.
0.0002
0.0005
O.OOIO
0.0020
0.0050
O.OIOO
0.0002
0.0005
O.OOIO
0.0020
0.0050
O.OIOO
Current density in amperes per square decimeter.
0.05
O.I
0.2
0-3
Time in hours and minutes.
oSyi
oiU
OI>^
01
16
08
04
02>^
32
16
08
05
1-04
32
16
10
2-36
1-18
39
26
5-12
2.36
i-iS
52
13
o6>^
03H
02
32
16
oS
05X
1-04
32
16.
io>^
2-39
1-04
32
2[
5-18
2-39
1-20
53
10-36
5-18
2-39
1-46
1 English Patent 3,537. Oct. 30, 1873.
* English Patent 10,126, Aug. 7, 1886.
» German Patent 43,35i, Sept. 25, 1887.
70 MANUI^ACTURE OF METALUC OBJECTS
In the manufacture of metallic paper from gold and silver, the
deposit of noble metal is usually strengthened by a galvanic de-
posit of baser metal in order to give a more durable and a more
intimate connection of the metallic leaf with the paper. Copper
or brass is mostly used in the case of gold leaf because according
to experience the back ground works through the thin sheet of
gold so that for instance copper gives to the sheet gold a reddish
tint, to silver a greenish tint.
Patent Claims,
1. The process of manufacturing metallic paper (papier-mache
or the like) consisting in first precipitating upon a suitable metal-
lic plate an extremely thin metallic coating either chemically or
galvanically, drying the same, furnishing the free surface of the
same with a binding material, laying upon this moistened paper
or paper pulp, and by a rolling process or pressure combining
these so intimately that the sheet metal together with the paper
can be detached from the support without being torn.
2. In the process of Claim i, the variations: (a) that in place
of a metallic skin two or more metallic films of different metals
superimposed upon each other are produced upon the backing
plate before the uniting of the metallic film or films with paper,
paper pulp, papier-mache or the like: (b). Instead of placing
the binding material first upon the metal-skin and then laying
paper upon it, the placing of the paper, paper pulp, or papier-
mache, or the like, already provided with a binding material upon
the dry metallic film.
FBOGESS OF ENDBUWEIT.
The above process has several short-comings such as the small
durability of the leaf metal upon the paper, and the necessity of
polishing each time the cathode plates, such that the price of the
metallic paper thus produced is about 25 cents per pack. C. En-
druweit^ claims to have invented a method by which the same
amount of metallic paper can be made at a cost of 2J/2 cents.
Patent Claims.
I. The manner of conducting the process of Patent 43,351,
I German Patent 68,561, June 16, 1891 ; American Patent 510.013-
MANUFACTURE O^ METALLIC FOIL 7I
Claim I, in which the insulating of the cathode plate from the
metallic layer is done by means of a sulphide layer, consisting in
moistening the plate with a i per cent, solution of alkaline poly-
sulphides or acid hydrogen sulphide in methyl alcohol.
2. For the facilitating of the union of the metallic precipitate
produced upon the cathode plate by Claim i, with sheet paper the
process of placing the cathode plate provided with a copper or
nickel precipitate for a short time in a solution of zinc sulphate,
being at the same time made the cathode of an electric current,
and treating the precipitate thus produced with a solution of am-
monium sulph-hydrate, mercaptan or allyl sulphide or of mixing
of the just-named materials with the paste used.
Gilding or silvering is produced by rubbing the copper pre-
cipitate with a suitable cyanide solution containing gold or silver.
FBOGESS OF SCHEOEDER.
E. Schroder^ patents in Germany a process for the production
of cathodes^ for the direct producing of polished metallic leaves
electrolytically.
Schroder covers a highly polished and burnished metallic plate
with a preliminary layer, a sort of enamel like material, which on
being melted upon it produces a thin fluid glaze consisting of
metallic oxides or similar mixtures. The lustrous polish of the
backing metal sheets passes through this smooth coating, and the
metallic precipitates upon these glazes are quite as dense and lus-
trous as if they had been produced upon the polished metallic plate
itself. A single enameling suffices for several precipitations since
the metallic sheets are very easily loosened and the plate is at once
ready for a new coating.
In this way sheets of gold, silver and nickel are easily produced. '
Schroder says that the enameling is injured neither in acid or
alkaline, hot or cold solutions ; but he assumes that the plates are
always cathodically polarized, and that the conducting of the cur-
rent is as explained by Streintz,^ according to which the metallic
oxides of the enamel being very finely subdivided as they are in
such glazes, conduct the current to the metallic background.
1 German Patent 123.658, April 6, 1900.
2 Zcitschr. f. Elektrochemie, 7, 921.
72
manufacture: of metallic obtects
SHEET GOLD BY SWAN'S FB0CES3.
J. W. Swan^ produced sheet gold electrolytically upon polished
thin copper plates using any usual gold plating bath; the metal
being made as thick as is desired. The thin copper plates are
then dissolved in ferric chloride solution or in nitric acid, leaving
the gold as thin perfectly coherent films. In this way leaves
have been made of less than o.oooi millimeter in thickness, trans-
lucent to light.
FBODUCTION OF FLANE SUBFACE3— BIEDEBS' FBOCESS.
Rieders^ invented a process for the manufacture of smooth
surfaces upon cast or rolled plates, galvanoplastically. The ob-
ject of the process is to produce highly polished surfaces upon un-
even surfaces such as are necessarily those of cast plates, and to
Fig. 14.
thus produce flat plates of a determined thickness. This process
is intended to displace grinding or polishing work and to avoid
the loss of metal connected with such processes. Rieders uses in
his really ingenious process the following apparatus:
Apparatus,
A polished glass plate G (Fig. 15) is fastened in the electrolyz-
ing tank and polishes the metallic plate M to be smoothed. The
spindle bent at K moves loosely in a bearing A of the metal plate.
The plate is pressed against the glass table G by the movable
heavy roller B, while the motion of the spindle causes the plate to
1 VElectricien XII. (1896), 173.
« German Patent 117,097, Dec. 15, 1899.
MANUFACTURE OF METALLIC FOIL
move eccentrically. ,The anode a is at the bottom of the vessel
parallel to the plate M.
Other Forms of the Apparatus.
The appartus can also be constructed as shown in Fig. i6. In
this the plate to be smoothed is moved backwards and forwards
by an eccentric motion while the weighted roll B produces the de-
sired pressure upon the glass plate G.
Manner of Working.
If a metallic plate which has cavities is coated in the ordinary
way with a metallic precipitate, either the precipitate will deposit
evenly and leave tiie cavities as they were, or by fast working
the precipitate deposits preferably upon the projecting points ac-
centuating the unevennesses. Rieders is of the opinion that the
metallic precipitate forms more slowly on the projecting points
74
MANUFACTURE- OF METALLIC OBJECTS
which come in contact witli the glass plate since they are continu-
ously ground off.
The action of the glass plate appears to the author, however,
to be not completely understood.^ But it must be assumed as a fact
'^F^tF
=H
^
'^E "fl nm
^^^:
^^^,
^r^ ■=^,
1
a
-'
' 3T '
i.k*
1
( aai
1
L
^i
=
I
^a > ! .■ ! until
i
1
• s
^M
ltft«a^™Wi
rt
ffi
L
a
M.
it
IS
- 2
— ^*
— — S — '-
1 plates are produced by the apparatus, such as
MANUFACTURE OF METALLIC FOIL 75
are used as plates in typographical work. There is a certain simi-
larity between this process and that of Dumoulin, which will be
described further on, yet Rieders says nothing of using a greasing
or insulating material to protect the projecting parts of the plate.
ELMORE'S PBOCESS.
F. E. Elmore^ has worked out mechanically a process for the
production of sheets. He makes especially with his apparatus
electrolytic metal sheets which are soft and which can be pressed
to a high polish ; such as for instance, copper, tin, silver, and the
like.
Apparatus,
The apparatus is shown in plan and elevation in Fig. 17. The
plate a is moved by the rollers b^ from left to right in the direction
of the arrows, while the precipitate in smoothed by polishers. The
apparatus is driven by the pulley q, the rollers by the worm gear-
ing. The polishers are of agate or of the like and rest upon the
cross rods m, which are rotated by the main shaft i by an eccen-
tric. The anodes u lie above and below the plate operated upon.
The prepared plates are taken from the movable table a, polished
on both sides.
Continuous sheets and leaves can be made by modifying the
apparatus so that an endless metallic ribbon is led over rollers, a
suitable intermediate layer being first deposited upon it in any
known manner.
X English Patent 9,214. July 15, 1886.
X. PRODUCTION OF WIRE, ETC
Advantages of Electrolytic Copper Conductors,
It has SO far been practicable to produce wire of electrolytic
copper only in such condition as to require a subsequent drawing,
at least always when it is to be sold as commercial wire. Excep-
tions to this statement may be the quite thin leaves which are used
as resistance ribbons. The high tensile strength possessed by
electrolytically precipitated copper (see the work and investiga-
tions of Hiibl) are possessed by no other electrolytic deposited
metal, at the most excepting nickel, concerning which according
to my knowledge nothing has been published as yet.
It is known that the conductivity of copper is extraordinarily
influenced by impurities and it is the chemical purity of the copper
produced by pure copper sulphate solutions which was primarily
so greatly prized. In 1870 J. B. Elkington^ patented a process by
which electrolytically pure copper could be worked into wire with-
out being melted.
FBOCESS OF ELKINOTON.
The method consisted in first precipitating thin copper plates
electrolytically vvhich were then cut into square strips. These
were drawn out as usual, and when round in shape thickened up
in the copper bath and again drawn.
FOX'S FBOCESS.
E. Fox^ improved on the above patent in relation to the copper-
ing of the wires, devising a suitable apparatus which had, how-
ever, no particular novelties.
ACHESON'S FROCESS.
E. G. Acheson^ patented a method of producing conducting
wires which contain two separate insulated conductors. The
metallic core of this double conductor is provided with a coating
1 English Patent 2,525. Sept. 2o» 1870.
* English Patent .3.4.S5, Aug. 27, 1879.
« German Patent 38.914, June 2. 1886; English Patent 7..^94, June 2, 1886.
PRODUCTION O^ WIRE^ ETC TJ
of asphalt or the Hke and by drawing through a box holding
graphite, is brushed over by mechanical means with a layer and
made conducting. The wire is then coated electrolytically with a
layer of copper, using at first a high current density and later a
lower one until the desired thickness is obtained. The high cur-
rent density must be used at first in order to copper over the
graphite quickly while the subsequent smaller current density has
the purpose of making the precipitate pliable. The bath tension
is three volts at the beginning, and after the graphite has been
coppered over this is reduced to one volt.
Patent Claims,
1. An electrolytic conductor consisting of a wire and insulating
envelope of fibrous material and asphalt, a thin layer of electroly-
tically precipitated copper, a further coating of a metallic alloy
and a protecting envelope.
2. The process of manufacturing the conductor described in
Claim I, consisting in coating over a layer of fibrous material and
asphalt by brushing with graphite and so making it conducting,
and passing it c6ntinuously first through a small bath using a high
electromotive force wherein is deposited a proportionate hard
crystalline layer of copper, and subsequently in a larger bath
where, by a feebler current, a softer and more flexible copper pre-
cipitate is produced ; and passing the wire then through a bath of
an easily fusible metallic alloy.
TAVEBNIEE'S PROCESS.
E. A. Tavernier^ proposed to strengthen thin copper wires
manufactured in the ordinary way by passing them through a
trough by means of. several rollers so that the path of the wire
through the bath is as great as possible.
The construction of the apparatus is very simple. The wire
runs inside the bath on insulated rollers either of porcelain or
glass and outside the bath upon metallic rollers which drive the
apparatus. Between the wires are the anodes, and the electrolyte
is continuously moved by means of a suction pump.
1 English Patent i,68o, Jan. 29, 1891.
78 MANUFACTURE OF METALLIC OBJECTS
FBOCESS OF SWAN.
J. W. Swan^ uses the principle of precipitating copper continu-
ously upon a cathode and then drawing it continuously through
draw-plates in the process itself, thereby producing a smooth sur-
face and the desired section.
Patent Claims,
1. The process of manufacture of wire by electrolytic precipi-
tation and drawing wherein the wire is simultaneously moved
through an electrolytic bath and backwards and forwards through
a drawing-plate.
2. The apparatus for the carrying out of the process of Claim
I in which at both ends of the trough A provided with draw-
plates FFj are placed drawing cones DDi and drums EEi, upon
which the wire is wound, and rotating these automatically by a
source of power so that the wire is moved alternately backwards
and forwards through the bath and the drawingplates.
Apparatus.
Swan uses for his apparatus that shown in Fig. i8. In a long
narrow trough A is an electrolyte of normal composition. The
two ends of the trough are closed by the plates FFi provided with
the drawing holes. Outside of the plates FFi are spaces CCi, in
which are two drawing drums DDi which keep the wire stretched.
From here the wire passes upon a much larger drum EEi in a
washing box where the wires are washed. The driving of the
drum EEi is by means of the pulley JJ^. The wires are connected
as cathodes with a source of current by the contacts M and the
current is lead in by the brushes N. The conductors N are passed
through glass tubes and insulated from the copper anodes ii by
bushings of non-conducting material. There are several such
conductors in a bath.
Placing of the Wires in the Apparatus.
The wires are so placed in the apparatus that at one end of the
trough A, for instance, the end adjacent the drum Di, the wire is
passed through the hole in the draw-plate Fi and then fastened
1 German Patent 63,030, Oct. 9, 1891 ; English Patent 19,586, Dec. i, 1890 ; see also Lum.
elektr. E. Andreoli, (1892), 45, 66.
80 MANUFACTURE OF ME:TALI.IC OBJECTS
Upon the drum Dj. The latter is then turned until a length of
wire equal to the length of the trough is wound up. The fastened
end is then loosened and the drum again revolved, the loose end
then being fastened to the drum Ei- This is continued until the
wire is completely drawn through and wound up upon the drum
whereupon the other end is passed through the drawing plate F
at the other end of the trough and fastened to the drum D. Eacfh
of these wires which serves as a carrier for the precipitate should
be at least four times the length of the trough A.
Operation,
For making copper or silver wires the bath is worked at a tem-
perature of 20° C. The apparatus serves also for the manufacture
of nickel wires, but must be altered to work with warmer solu-
tions. For copper a tension of i volt is used and the bath con-
tains not more than 3 per cent, of free sulphuric acid, otherwise
the copper suffers in regard to tensile strength. The table in the
appendix gives exact figures concerning the current strength
used. It is self-evident that the current strength to be used is
regulated according to the number of meter lengths of wire being
electrolytically produced as well as according to the diameter of
the same which regulates the surface.
The rate of drawing is regulated according to the current den-
sity used and the dimensions of the drawing* holes. With a nor-
mal current density of i to 1J/2 amperes per square decimeter the
velocity of drawing would not be more than i meter per minute,
in order to bring the surface of the wire as often as possible in
contact with the edges of the drawing holes and so to produce a
compression and smoothing of the deposited copper.
Two electric motors ee^ are best adapted for driving the
apparatus, each furnishing i horse-power. These two motors
rotate the drums DD^ alternately so that the wire, becoming al-
ways thicker as the deposit increases, is drawn forwards and
backwards through the holes of the draw-plate FFj and wound
up on the drums EEi. While the wire is drawn by the drums D
or Di from the trough, fresh wire is simultaneously wound off the
other drum D^ or D and is carried forward into the trough by the
winding drums and there receives a fresh coating. When this
PRODUCTION OF WIRE^ ETC
8l
newly coated and thickened wire comes to the other end of the
«
trough it is drawn through the draw-plate there and wound up
at that end ; then the direction is changed and the operation is so
conducted until, because of the deposit of metal from the bath,
the desired length of wire has been produced.
The two driving drums D and Di could be automatically oper-
ated by an arrangement to be described later, or in case electric
motors are used for driving, a suitably connected switch could
be operated by a contact, best placed on the end of the wire so as
to throw the electric motors e and^^ alternately into and out of
action. It may be seen in Figs. i8 and 19 that each of the two
Fig. 19.
drums D and D^ is driven by its own electric motor by the pulleys
/ g and worm gear drive k L If it is desired the source of power
can be directly connected with the screw shaft /i by a coupling.
A pawl m fastened to the gear wheel is held against the ratchet
wheel o fastened upon the axle of the drum D, by the pressure
•of a spring n. The spur wheel q fastened to the gear wheel / on
one of its spokes is turned around one tooth at each revolution of
82
MANUI^ACTURE OF METALUC OBJECTS
the gear wheel / by striking against a fixed projection of the latch
r. The latter prevents a reversal of the wheel q. At each revo-
lution the wheel q lifts by a small rod the latch m out of the
toothed wheel o, so that the drum can turn freely in the reversed
direction by a pull of the wire from the drum at the other end
of the trough.
Simultaneously with the lift of the latch or immediately there-
after the current-making contact m fastened on the wheel q
touches another contact and makes electrical connection between
this and a current closing piece upon the wheel I, whereby the cir-
cuit is closed by the switch throwing the formerly operating
motor out of the circuit and the other electric motor into the cir-
cuit so that the direction of motion of the wire is reversed. In
this way the wire is mechanically drawn backwards and forwards
until the desired length has been produced and the wire is of the
desired thickness.
According to the calculations of the author a trough lo meters
long should produce in lo hours the following quantities, if it is
assumed that 30 draw-holes are used so that there is exposed to
the electrolytic deposition 300 meters of wire at one time.
Diameter
of
wire in
mm.
Weight pro-
duced m
10 hours
Kg,
Current used
for whole
apparatus in
amperes. 1
Surface per
running meter
in square
decimeters.
Area of
wire
in square
millimeters.
Weight
per meter
in
grams.
I
14.2
120
0.31
0.79
6.99
2
28.4
240
0.62
3.14
27.96
3
42.6
360
0.93
7.07
62.95
4
56.8
480
1.24
12.57
I I I. 90
5
70
600
1.55
19.64
174.80
It is to be seen from this compilation that the smaller wires are
made under unfavorable conditions, because the cost of operating,
interest and sinking fund would be increased when making them.
Cost of Plant,
For a wire-drawing establishment to produce 100 kilograms of
copper wire daily of various sizes between i and 5 millimeters in
diameter the cost of plant would be as follows :
1 Current density used 1.3 amperes per square decimeter.
PRODUCTION 01^ WIR^^ E:TC 83
3,5(X) square yards of ground $ 1,625.00
Buildings with 2,000 square yards of shedding 875.00
Boiler, 70 square yards of heating surface with mason-
ry and chimney 3,000.00
60 H. P. steam engine, including foundation, etc .... 2,500.00
Main generator, 35 Kw., with switchboard 1,250.00
35 Swan apparatus, including electric motors 12,500.00
Switchboard, measuring instruments, conductors, etc 1,125.00
Erection, packing, freight i ,500.00
Putting in operation 625.00
Total cost of plant $25,000.00
Operating Costs.
For a plant of the above capacity the operating costs would be :
Coal: 3.3 lbs. per H. P. -hour, per year of 300 days of
24 hours each = 650 tons at $3. 75 $ 2,437.50
72 tons of blister copper at $237.50 17, 100.00
Wages of the foremen i ,500.00
Wages of one clerk 500.00
Wages of one engineer 375-oo
Wages of two firemen 550.00
Wages of ten workmen 2,500.00
Dynamo brushes, grease and polishing material 750.00
5 % interest on capital 1,250.00
10% sinking fund 2,500.00
Light, heating, etc 250.00
Total yearly operating cost $29,712.50
Profits.
Assuming the price of copper wire at 41.5c. per kilogram
(18.64c. per pound) and that the above plant produces yearly
72,000 kilograms = 159,400 pounds, the profits would stand as
follows:
72,000 kilograms of wire at 42.5c. per kilogram
(18.64c. per pound) $29,880.00
Value of 0.4% silver content of the blister copper at
$19.00 per kilogram ,. 5,500.00
Value of 0.003% gol<l content at $700 per kilogram . . i ,500.00
Total $36,880.00
Operating cost 29,712.50
Yearly profits $ 7,167.50
Corresponding to a dividend of 28 per cent.
84 MANUFACTURE OF MIvTAIXIC OBJECTS
Applications.
The. fundamental condition for the profitability of this attract-
ive process is the obtaining of rich blister copper since it can be
easily calculated that if electrolytic copper were used which is
free from the noble metals, the process would no longer be profita-
ble. Whenever the price of pure electrolytic copper would be
over 28.75c. per kilogram the process would also be unprofitable.
PROCESS OF SANDEES.
R. D. Sanders^ obtained a patent tc^ether with a number of
supplementary patents, the claims of which are as follows :
The production of wire or ribbon electrolytically by means of a
conical, prismatic or otherwise shaped cathode, the working sur-
face of which is spirally grooved with the adjacent grooves in-
sulated from each other.
A cathode for the production of wire or the like electrolytically
using a cathode with non-conducting insulated spaces, similar to
that of patent 71,838, characterized by so forming the non-con-
ducting spaces or the conducting cathode spaces that the desired
sectional shape of the wire or ribbon can be produced, and that
the metal can be deposited on either, sideways or in a direction
perpendicular to the cathode surface.
A method of carrying out the process of the above patent for
the production of wire and like objects, characterized by placing
in the grooves of the mandril used as cathode a wire which facili-
tates the detaching of the electrolytic deposit.
The production of wire electrolytically using a starting wire as
a depositing surface, which wire is wound upon a spindle so as to
be detachable, and instead of being sunk into deep grooves is
wound upon the surface of the cylinder or in such shallow de-
pressions that the wire projects above the cylindrical surface of
the spindle so that rubbing contacts would lie continuously on the
starting wire or on the deposited metal.
Principle of the Process.
From these patent claims it can be seen that Sanders works
1 See also Zeitschrift f. Elektrochemic, i, 428.
German Patent 71,838. Feb. 16, 1892 ; English Patent 7.960, May 8, 1891,
German Patent 73 824. May 18. 1893 : KngHi^h Patent 12.382. July 4. 1&92.
German Patent 78,361, March 22, 1894 ; English Patent 13,931. Jwly 18, 1893.
German Patent 104,185, Aug. 26, 1898.
PRODUCTION OF WIRE^ ETC 85
Upon the principle of a revolving roller using a conducting roller
wound spirally upon a mandril, deposits metal electrolytically
upon it, and thus produces a metallic deposit like a spiral spring.
Sanders thereby saves much space and simplifies considerably the
apparatus of Swan. The wire is loosened from the backing and
drawn through the ordinary apparatus whereby the seams of the
spiral of the flattened surfaces which are against the mandril are
caused to disappear.
First Apparatus.
Sanders' first apparatus was constructed as follows : A roller
was made of wooden disks clamped tc^ether and placed in a
holder and covered over with a non-conducting or a conducting
material. In this coating a spiral groove was cut or in the case
of the non-conducting coating was then covered with a conducting
material either in the grooves or upon the ridges. If the coating
was of metal the grooves were filled with wax or a similar non-
conducting material. The wax having hardened the whole roller
is turned so that the ridges of the metallic surfaces of the spiral
grooving are visible. If a conducting material is to be used the
roller with its coating is turned smooth and is given a metallic
coating such as tinfoil. The coating having become hard a spiral
groove is cut in which leaves upon the grooves a strip of the
metallic coating in the form of a spiral line. The roller is as
large as can conveniently be used which allows easier winding
off of the finished wire. The coating is best made of asphalt or
the like.
Use of Finishing Tools.
While the roller is being rotated burnishing tools can be ap-
plied to it. As soon as the tools arrive at one end of the spiral the
direction of rotation of the roller is reversed. The burnishing
tools are carried in frames which move in guides fastened to the
sides of the vessel. The motion of the burnishing tools is given
by the spiral winding of the roller itself.
Second Form of Apparatus.
In the first apparatus the metal showed a tendency to grow
upon the non-conducting parts, so that the patent 73,824 was
MANUFACTURE OP METALLIC OBJECTS
directed towards the use of angular cathodes. In this manner
precipitates of nearly circular cross-section are obtained.
Fig 20 shows a cathode carrier with recessed construction. Be-
tween the strips b are layers c of non-conducting material in
which are embedded metallic plates a upon which the precipitate
is formed. Fig. 2! shows a cathode carrier upon which the metal
can be deposited spirally in great lengths. If wished, this cathode
carrier can also be made of a cylindrical form. In all cases the
visible surfaces of the metal strips upon which the deposit takes
place are not so wide as the bottom of the grooves, so that the
deposited metal can spread sideways as it increases in amount
until the desired cross-section or the desired amount has been
reached. In a similar manner it is evident that a large variety of
cross- sectional forms can be produced, as for instance, in Fig. 22,
in which a spiral groove is formed upon a cylindrical metallic
mandril rf. This groove is filled with non-conducting materia!,
and then the whole cylinder turned down, leaving upon the outer
surface a thin visible metallic line a. The metal precipitated upon
the latter takes then an almost circular form. In taking off the
wire it is self-evident that the surface under the deposit will ap-
pear as a long groove which can be, however, pressed together
afterwards. For producing longer wires the cathode surface is
constructed in the manner shown in Fig. 23. The metal band is
rolled up spirally and the intermediate spaces filled with non-
conducting material. The flat sides are turned ofF or cut down to
PRODUCTION C
the edges of the metallic band so as to leave visible on each side
a thin screw-like metallic surface a.
If the deposited metal is to be rubbed during the deposition an
arrangement, as shown in Fig. 24, is used in which the cathode
carrier ;' is pivoted in a vessel k and a roller or a rubbing pad I
lies loosely upon the upper surface of the cathode. This roller
must have sufficient weight to smooth out the deposited metal by
its motion.
Loosening of the Wire.
The separating of the backing wire from the precipitate is
facilitated by laying in the grooves of the mandril or roller a iiue
wire which forms the true depositing surface. During the elec-
trolysis the groove is filled up with the deposited meta! and at the
end the metallic precipitate can be rolled off with or without the
original wire. It is required to make a smaller groove in which
the wire is laid so that it cannot be surrounded by the precipitated
ca manufacturh of metallic objects
metal. The mandril consists of any suitable material such as
porcelain or glass.
Upon the mandril is a spiral groove b in which the fine wire c
Fig. 26.
is laid. The ridges or wires e form a conductor between the fine
wire c and the larger coductor d, their free ends rest upon the
upper surface of the wire c and the other end fastened into holes
in the conductor d which latter is held by a bracket / fastened to
the holder g. If the deposited metal is such that it does not ad-
here to the original wire, such as is the case with lead it can be
removed without disturbing the original wires.
In those cases where the conductor is arranged outside of the
mandril or kernel the latter is hung upon a rotating shaft, and in
order to avoid deposition of metal upon the rods e is so hung that
a part of its circumference extends above the level of the fluid.
This manner of supporting the mandril can also be used when the
material of the mandril encloses the conductor. The rotating
PRODUCTION OF WIRE^ ETC 89
shaft h is turned in any suitable manner by the pulley i, (see Fig.
2y)y and preferably above the level of the liquid in the trough g.
By this arrangement when the shaft Ji is rotated the mandril a is
by friction slowly rotated in the fluid. Metal is deposited upon
the wires c and the pencils e carry the current.
Operation,
In operation several shafts are run by a common shaft the ro-
tating speed being best about i meter per minute. The power re-
quired per roller varies according to the number of burnishing
tools, the size of the trommel and the surface velocity, and is be-
tween 0.2 and 0.5 HP. The power necessary for electrolysis is
not included in this. The bath tension varies between 0.25 and
0.7 volt. In order to obtain as great a tensile strength and the best
conductivity of the wire it is recommended to use pure electrolytic
copper or blister copper containing at least 98 per cent, copper.
The burnishing tools are best made of agate of proper shape to
give to the wire the desired fonn in which it is to be sold. For
round wires agate tools are used, which are cut with a semi-
circular groove in them.
Cost of Plant.
In order to compare this process with that of Swan the cost
of the plant will be calculated likewise for a production of 100
kilograms of copper wire per day; the wire being assumed as 5
millimeters in diameter, which can then be drawn to any desired
size.
COST OF PLANT.
Ground, about 10,000 square feet $ 250.00
Building for electrolytic and drawing plant, with
office and dwelling for the superintendent 2,500.00
Boiler of 300 square feet heating surface, including
masonery and foundation 1.375.00
Steam engine, 30 H.P 1,750.00
30 Sanders' apparatus, 3 feet long and 2 feet diameter
including burnishing tools 6,375.00
7,500 gallons of electrolyte 875.00
10 Kw. dynamo 625.00
Switchboard with equipment and conductors i ,000.00
90 MANUFACTURE OF METALUC OBJECTS
Drawing apparatus and reels i,2oo.cx>
3elts and pulleys 1,125.00
Washing tanks 200.00
Erection, packing, freight 500.00
Starting expenses 925.00
Total $18,750.00
OPERATING COST.
The following values can be assumed:
Coal 3.3 pounds per H.P.-hour at $3.75 per ton = per
year $ 1,250.00
72 tons of 98 per cent, blister copper at $237.50 per ton 17,100.00
Superintendent 1,500.00
Clerk 500.00
One engineer 375oo
Two firemen 550.00
Fifteen workmen 3i75o.oo
Dynamo brushes, lubricating oil, etc 750.00
Five per cent, interest on capital 937- 50
Ten per cent, sinking fund on the capital 1,875.00
Lighting, heating, etc 250.00
Total, about $28,837.50
PROFITS.
Assume the same selling price of the wire, that is 41.5c. per
kilogram (18.87c. per pound).
72 tons of wire $29,880.00
Value of 0.4 per cent, silver in blister copper at $19.00
per kilogram 5,500.00
Value of 0.003 per cent, gold in blister copper at
$700 per kilogram 1,500.00
$36,880.00
Operating cost 28,837.50
Yearly profits about $ 8,042.50
Corresponding to a yearly dividend of almost 43 per cent.
It is therefore seen that the Sanders process possesses a better
outlook than the Swan, starting with the same conditions. I must
remark that the price of the Sanders apparatus has been found
by approximate calculation, and there may be some further varia-
tion in the value from that given.
PRODUCTION OF WIRE, ETC 9I
PROCESS OF FORSYTH AHD FLETCHER.
A process similar in principle to that of Sanilers for producing
metallic ribbons and rods was patented by Forsyth and Fletcher.
The apparatus used by them is constructed as follows:'
Apparatus.
The wrought iron cylinder F closed at both ends is covered at
the ends with an insulating layer B, on the sides with a metallic
covering of easily worked metal G. (Figs. 28-30). A spiral
groove of trapezoidal cross-section is cut in the metallic sheath
with the larger base of the trapezium beneath and in these grooves
strips of insulating material K are placed, which may be of rub-
ber.
This roller is then hung as a cathode in an electrolytic metallic
vessel and rotated, when the metal deposits between the rubber
strips K, so that when the electrolysis is stopped it may be wound
off as a metallic band, or if the electrolysis is carried on longer
may be obtained as wire or rod having a cross-section determined
by the form of the rubber strips between which it is deposited.
PROCESS OF C0WFER-C0LE8.
To complete the list of these processes I mention that of Cow-
per-Coles, by which sheet metal or metal strips or wire may be
produced in any desired lengths.
Apparatus.
Cowper-Coles' deposits the metal upon an endless copper band
which is drawn so slowly through the electrolyziiig vessel that
' ABieriean Patent 57o,!2s, Oct. 17, 1896 i see also ZeiUchr. f. Elektrochemle, 3, J46.
, English Patent 2,998, 1895 : Zeitschrift t. Elektrochemie. a. 64S.
92 MANUFACTURE OF METALLIC OBJECTS
the precipitate on leaving the bath is of the desired thickness; it
Fig. 32.
is then separated from the band outside of the batli and rolled up
on a reel. (See Figs. 31 and 32).
XL MANUFACTURE OF BODIES OF LARGE
SIZE
The largest application of electrolytic metallic depositing pro-
cesses is the manufacture of tubes of all varieties; but before
turning to this use we will describe those processes dealing with
the manufacture of large bodies such as large vessels, parabolic
mirrors, etc.
PROCESS OF J. ELEIN.
A completely new method of producing bodies having the shape
of surfaces of revolution of most varying kinds was patented by
J. Klein.^ This investigator likewise compresses the metal as it
is being deposited by causing a rotating cathode to roll against a
corresponding shaped straight or grooved support.
Patent Claims.
1. The process for the compressing and forming of electrolytic
precipitates characterized by using roller-like cathodes of any de-
sired number and profile and rolling them upon corresponding
straight or grooved supports in an electrolyte bath until the end
of the operation.
2. The carrying out of the process described in Claim i by the
use of an apparatus consisting of one or more frames in which
(according to the number of the bodies to be produced at once)
either one, two or more rotating mandrils are rolled upon a verti-
cal, inclined or horizontal or curved support, backwards and for-
wards, until the precipitate upon the mandril is of the desired
thickness.
3. The apparatus of the kind described in Claim 2 in which
the mandril is hollow and open at one or both ends and the metal-
lic deposit upon which is compressed by smoothing irons while
the deposit upon the inner surface of the mandril is compressed
by one or more rollers carried upon a rotating frame.
1 German Patent 79,764, March 31, 1892 ; English Patent 563, Jan. 9, 1895 ; see also 2ieit-
schrift f. Elektrochemie, 1, 161 ; Dr. G. I^angbein.
94
MANUFACTURE Oi^ METALLIC OBJECTS
4. An apparatus of the kind described in Claim 2 so altered that
it or at least the frame is arranged as a turning rack within whose
sweep the mandrils are rotated and so radially movable, while the
form has the shape of a fixed hollow cylinder the inner or outer
circumference of which is rolled by the movement of the turning
rack.
5. The apparatus of the kind described in Claim 2 in which the
frame is arranged as a rotating disc which in its motion rolls the
mandrils, arranged radially about its turning axis, upon a hori-
zontal plate.
As far as concerns the process used by Klein it can be judged
from the same how the process is carried out since the different
constructions of the mandrils as well as the whole apparatus are
minutely described.
Manufacture of the Mandrils.
The mandrils upon which the metal precipitate is deposited con-
sist either of metal or wood and can be hollow or solid. See fig-
ures 33 to 36.
f f f t
Fig. 33. Fig. 34. Fig. 35. Fig. 36.
Fig. 33 shows a solid mandril. Fig. 34 a hollow one, Fig. 35, one
which is stiffened by an included tube, while in Fig. 36 the man-
dril is stiffened inside by one or more cross ribs.
7<
^^
Fig. 37-
The adjustment of such hollow mandrils is made clear in Fig.
37. The mandril is closed by the plug e, which has a small screw
plug b and a conducting contact e, the latter having the form of a
cap. The hollow mandril is usually filled with sand or lead shot.
The stiffening webs of the mandril are then filled up by the appli-
MANUFACTURE OF BODIES OF LARGE SIZE 95
cation of gypsum, glue, clay, or the like, or at once coated with an
easily fusible and polishable material, such as wax, lead, paraffine,
etc. The form is then rolled upon the properly prepared former
giving it the form of rotation desired. Instead of rolling the man-
dril with its plastic coating it may also be turned down to the
shape desired ; the surface of the roller is then made conducting
in the proper way if it is of non-conducting material. The ar-
rangement shown in Fig. 38 is particularly designed for produc-
PiB- 38.
ing hollow rotated bodies. It consists of two exterior parallel
guides a screwed down to a base k. Between these guides is the
form c having the profile of the desired article. The hollow body
is carried^ by the tube d, forming the center of the mandril. The
ends of the spindle j are furnished with screws in order to hold
the article fast in position. On both sides of the spindle are roll-
ers g and guides k so that the guides a lie between them. The
mandril is fastened ih position on the spindle by the nuts b.
The tube d is then coated with clay and rolled backwards and
forwards upon the base c, previously rubbed with oil, and rolled
until the desired form corresponding to the base has been ob-
tained. The guides k roll freely upon the track a. The mandril
is now burned and then dipped into a mixture of resins or wax,
after which it is again rolled upon the former in which operation
the rings U placed upon the sliding guides regulate the thickness
of the coating. In putting on the wax coating the burned form is
wetted with water to prevent the adhesion of the wax. The man-
dril so coated is then made conducting either with graphite or
with an easily fusible alloy if the mandril has not been coated
with wax.
For the forming, various arrangements can be used and Figs.
39 and 40 show several types. This forming is to be distinguished
96
MANUFACTURE OF METALLIC OBJECTS
from the forming of the mass of clay on tlie forming table since
the forming arrangements to be described serve to compress and
polish the precipitate during the electrolytic process. Figures 39
and 40 show quite simple apparatus.
Simple Form of Apparatus.
In the electrolyzing bath A the.forming plate h is placed on the
supports ^, being of hard material like glass or procelain not at-
tacked by the bath. If several mandrils are to be simultaneously
worked they can if they have the same profile be rolled upon the
same forming plate if they are put together in the frame t, being
so placed in the frame that they can be easily taken out one at a
time. The conducting of the current to the mandrils is by the
wire Wi by means of the brush L fastened to the frame and the
already mentioned contact pieces on the ends of the mandrils.
The anode is above the forming mandrils and parallel to their
direction of motion.
As soon as the current is put on metal begins to deposit on the
manufactcrE of bodies of lakge size 97
forming shape, and the frame is moved backwards and forwards
upon the forming plate by an eccentric, Figs. 41 and 42 show a
cross-section of the forming plate.
Fig. 43 shows a form of apparatus which is a multiple of that
shown in Figs. 39 and 40.
The longitudinal and cross- sect ions of a forming vessel are
shpwn in Figs. 44 and 45. In this several forming cylinders can
be simultaneously worked over in a vertical direction in which
case the frame is carried by the rollers f^ and the mandrils are
pressed against the forming plate by the rollers r^. The frames
can also be pressed against the forming plate by adjustable wedges
or in any simitar manner. The anode plates are bent to corre-
spond approximately with the profile of the cylindrical forms and
take part in the motion.
Circular Apparatus.
Another shape of the apparatus is that having a trough-shaped
arrangement of the forming plate. The best form is that of a
9» MANUFACTURE OF METALLIC OBJECTS
hollow cylindrical arrangement of the plates because in that case
both the forming plate and the anode can be given the desired
profile by a turning operation. Such a form of apparatus is
shown in Fig. 46, in which b is the forming plate in the shape of a
cylinder and fastened to the outer case of a holder c; d is the turn-
ing frame carr ng the cjlndrcal anode / and two discs e
on the axle of the fomung cylinder lie in slits opening out-
MANUFACTURE OF BODIES OF LARGE SIZE 99
wardly. If the turning frame d is moved alternately in one or the
other direction whereby the cylindrical formers are pressed, either
simply by centrifugal force or by any other method the precipitate
is smoothed out in the same manner as if the forming plates were
plane. The apparatus of Fig. 47 is constructed similarly with the
slight additions that the cylindrical forming plates are placed ver-
tical and tlie cylinders travelling over them are placed inside.
lOO MANUFACTURE OF METALLIC OBJECTS
A radial arrangement of the cylindrical rollers upon a concen-
trically moulded forming disk is shown in Fig. 48. In Fig. 49 the
forming of the precipitate upon the inner and outer surfaces of
the two hollow forming cylinders is shown, in which internal
rollers w and an external forming plate p are used. In this case
two anodes must be used, an inner and an outer, marked a and b.
Advantages and Applications.
The advantages of the Klein process are evident without further
discussion. It requires a minimum of space and a small amount
of electrolyte, It is able to produce any described article having
for its outlines a surface of revolution, which is not the case if the
cylindrical formers are used without the aid of the smoothing or
forming plates.
The process is very suitable for many purposes and experiments
have been made to produce by it corrugated boiler tubes. Since
the most various profiles can be obtained in this way the Klein
process has decided advantages over the many methods for the
production of tubes.
NTJSSBAUU'S P£OC£SS.
The process of A. Nussbaum,' consists in the manufacture of
copper vessels and the like using a fluid under pressure between
the deposit and the mould. This is done in the simplest manner
by causing the fluid under pressure to pass through a valve-like
arrangement at the inner surface of the dejMJsit and to raise up the
latter and pass between it and the mould ; the electrolytic deposit
is extended at one side of the mould into a nipple by means of a
German Patent 91,146, May iB. 1S96 ; see also Sngelbiatdt ; III Interna tiona lee CoDgr.
f. ansew. Cbemie : Cbem. Zeitg, J3, 649. (1898)-
MANUFACTURE OF BODIES OF LARGE SIZE
bolt or protuberance in tlie mould which on being; screwed out
leaves a tube which serves as a means of introducing the fluid
under pressure between the deposit and the mould.
The apparatus for the practical carrying out of the process is
shown in the accompanying figures.
Figures 50-54 show the mould with the valve v which is then
coated with the deposit u. Fluid under pressure is then pumped
Fig. 50. Fig, SI.
into the center of the hollow mould or best by means of the pres-
sure tube «, where it lifts the valve v at the surface of the mould.
The pumping in of the fluid must proceed slowly at first in order
to give it time to insinuate itself between the surface of the mould
and the precipitate and so to enlarge the elTective pressure sur-
faces; otherwise the precipitate may rupture at the valve. The
complete separation of the precipitate is indicated by a slight
crackling; with larger objects several cracklings may be heard
corresponding to the loosening of the different parts. After a
few further strokes of the pump the precipitate separates from the
'mould.
I02 MANUFACTURE OF METALLIC OBJECTS
The Valve,
The valve v must close tightly in order to prevent the entrance
of the fluid under pressure into the mould and to perfectly com-
plete the unbroken surface of the mould. The best shape is a
slightly conical valve.
Small valves keep tight by simple greasing, larger ones must be
held down by a suitable spring f, or by a bent wire d with a pro-
jecting wedge k fastened to an enlargement v^ of the valve. The
spring / under the influence of pressure of the fluid slides easily
out of its seat and thereby leaves the valve open. The bent wire
d must be freed by the loosening of the wedges k before pumping
in the pressure fluid in order to render possible the pressing out
of the valve v.
Vessel moulds having a convex bottom may be provided with
smaller valves, but these require rather high pressures. Vessels
with flat bottoms must, however, have valves almost the size of the
bottom and be strong enough to withstand the pressure ; otherwise
the flat bottoms will bulge out or even burst. In the manufacture
of open tubes it is recommended to make them with a hemispher-
ical auxiliary bottom and valve because the convex depositing
surfaces stand the pressure better which is necessary for the re-
moval of the tube.
The valves are easily loosened from the precipitate, if neces-
sary, they are given several blows with a wooden hammer. If a
tube with an open end is to be made the precipitate at this end is
cut off, the valve inside pushed out. In making small tubes, the
tube serving as the mould can be also the pressure tube, but must
in this case have a greater thickness of walls than the precipi-
tate. For larger articles a special pressure tube is used in which
case the tubes acting as the moulds can be made correspondingly
slimmer because they do not have to withstand inner pressure. The
separation and loosening of the precipitate is easier in this case
because the mould is somewhat compressed by the pressure and
the pressure fluid can more easily find its way along the precipi-
tate.
The Pressure Tube.
The pressure tube is either fastened permanently to the mould
MANUFACTURE OF BODIES OF LARGE SIZE 103
by means of flanges or is pressed firmly against the flat bottom of
the vessel and its free end arranged for connection with the pres-
sure pump. It is better to place them in the axis of the mould at
the bottom of the same. In the case of long articles in which the
precipitate cannot be axially removed from the mould, several
pressure tubes can be placed at suitable distances from each other.
By pumping the pressure fluid into the several pressure tubes the
precipitate can be successively removed.
Raising of the Precipitate.
The loosening of the precipitate is possible, Fig. 54, in the case
of open vessels without using a valve. The metallic tube is closed
at its open end by means of an auxiliary piece into which a bolt
passes. When a sufficiently thick deposit has been formed on the
pressure tube the auxiliary piece and the bolt, of which the head
of the latter has been protected from receiving a precipitate by
means of a coating is then turned out and the tubular nipple- form
of the precipitate is then fastened to the pressure pump, for in-
stance, by tapping it with a screw-thread. The separating of the
precipitate results as when using the valve arrangement.
Patent Clai^ns.
1. The process for the loosening of electrolytic precipitates by
pumping in a fluid under pressure between the precipitate and the
metallic surface.
2. A method of carrying out the process of Claim i, charac-
terized by the use of a pressure fluid which raises a valve-like
movably arranged part of the surface together with the precipi-
tate thereupon and thereby passing between the precipitate and
the mould; in connection wherewith for the introduction of the
pressure fluid the use of either a hollow formed mould itself (m.
Fig. 50) or a particular pressure tube (r, Fig. 50 and 53) fas-
tened against the body of the mould.
3. A second method of carrying out the process of Claim i, in
which the electrolytic precipitate is prolonged at an open place of
the mould by means of a bolt (b, Fig. 54), for the purpose of con-
necting to the nipple formed pressure tube after the withdrawal
of the bolt.
I04 MANUFACTURE OF METALLIC OBJECTS
As is shown in the following calculation of profits* the Nuss-
baum process should soon replace the old coppersmiths' work.
COST OF PLANT.
For a plant with a daily output of 900 kilograms, or yearly 300
tons of copper vessels and using 100 HP.
(a) Dynamo $ 3,000.00
Measuring instruments and switchboard 212.50
Main conductors 87'50
Unforseen 125.00
Erection 337-50
(b) 200 baths with stirring apparatus, without solu-
tions and anodes, at {106.25 21,250.00
(c) Pumps, lathes and various tools 2,512.50
(d) 3,000 moulds at I4.25 12,750.00
(e) 81 tons of anode copper at {300 per ton 24 300.00
(f ) Electrolyte (CuSo^ -|- H^SOJ 7,500.00
(g) Water-power plant with turbines at |i 27.50 per
H.P 12,750.00
(h) Buildings, 1,700 square yards shedding 14,375.00
200 square yards brick building . ... 2,550.00
5,000 square yards ground 2, 125.00
(i ) Purchase of patents 25,000.00
(k) Working capital 12,500.00
Total 114^37500
OPERATING COST ( YEARLY).
1. Wages: 50 workmen at J191. 25 $ 9,562.50
1 foreman 500.00
2 engineers at I375.00 750.00
2. 300 tons of electrolytic copper at I300 per ton . . . 90,000.00
3 per cent, waste of anode material 2,700.00
3. Lubricating material, etc 450.00
4. Sinking Fund.
10 % of the electrical equipment (13,875) 387.50
15 *' " bath equipment (121,250) 3,187.50
10** *' machinery equipment (12,512.50). 251.25
15 " ** cost of moulds (J12, 750) 1,912.50
5 ** ** cost of electrolyte ($7,500) 375.oo
5 ** " cost of the water-power plant
($12,750) 637.50
4*' *' building cost ($19,050) 762.00
8" ** cost of the patents 2,000.00
1 The following data I owe to Chief Engineer Engelhardt.
MANUFACTURE OF BODIES OF I^RGE SIZE IO5
5. Interest :
5 % of the working capital (12,500) 625.00
2 ** *' cost of the anode copper (24,300). 486.00
6. General expenses :
Superintendent $ 1,250.00
Two clerks 1,500.00
Insurance 250.00
Taxes 6,250.00
Diverse expenses 3,300.00
$ 12,550.00
Total 1127,136.75
Rounded to 127,50000
PROFITS.
Assuming the value of the 300 tons of ware at 1575.00
per ton $172,500.00
Operating expenses 1 27,500.00
Yearly profits $ 45,000.00
Corresponding to a dividend of 32 per cent.*
The following patents are of smaller importance, but are put in
for the sake of completeness.
SUTHERLAND'S FBOCESS.
W. S. Sutherland^ precipitates metal upon easily fusible forms,
to produce surface condensers and steam generators.
ELMOBE'S PROCESS.
F. E. Elmore^ patented a process for the manufacture of hollow
vessels and evaporating pans in which the forms were coated first
with a layer of adhering and then with a coating of non-adhering
copper. The forms thus treated were then placed upon a hori-
zontal shaft in the bath and connected up as cathodes, using as
anodes either copper strips or strips of insoluble material arranged
at equal distances from the cathode. The shaft carrying the
cathode is rotated and the precipitate is worked by smoothing
tools.
1 The differences in the cost of labor in Europe and in America would modify many
of these assumptions. — Translator.
* English Patent 8,054, May 22, 1884.
' English Patent 10,451, Sept. 3, 1885.
I06 MANUFACTURE 01? METALLIC OBJECTS
FBOCESS OF DAVIS AND EVANS.
J. W. Davis and J. O. Evans^ produce hollow metallic ware by
using sectional forms upon which the metal is deposited while the
electrolyte is circulated in the usual manner.
C. G. Haubold produces perforated hollow metallic cylinders
by fastening upon the forms upon which the metal is to be pre-
cipitated rods of non-conducting material which on being removed
leave a cylinder with corresponding perforations.
FBOCESS OF A. ERUOEB.
Miss A. Kruger^ obtained a patent for the production of flexible
objects by the electrolytic precipitation of metal, the several layers
of which are separated either partially or totally from each other
by intermediate layers so as to be sufficiently flexible in spite of
their solidity.
Patent Claims.
1. A process for the production of flexible elastic bodies elec-
trolytically, characterized by producing alternately repeated elec-
trolytic deposits of metal and intermediate layers completely or
partially separating the metallic layers from each other.
2. A method of carrying out the process of Claim i, in which
the metallic layers are deposited upon an elastic support in order
to produce greater elasticity of the coating.
3. The methods of carrying out the processes of Claims i and
2, in which the metallic layers consist of different metals or alloys
in any desired order or sequence.
4. A method of carrying out the processes of Claims 1-3, in
which the metallic precipitates are smoothed or pressed mechan-
ically.
The process consists practically in the use of various electro-
lytes and certain changes and sequences for the obtaining of
metals and alloys of fixed composition, which later may be caused
to unite with each other by heating, and the smoothing of the sur-
face by a suitable smoothing apparatus.
1 English Patent 8,io8, April 20, 1892.
2 German Patent 95,761, Sept. 20, 1896; English Patent 26,102, Nov. 9, 1897; see also
Zeitschrift f. Elektrochemie, 6, 356.
MANUFACTURE OF BODIES OF LARGE SIZE IO7
Examples of the Process,
As examples are mentioned : In order to produce a body with
a screw-like surface a conical hollow spindle of metal is used
which is provided with a coating of graphite mixed with spirits
of turpentine, which after being completely dried, is smoothed
over. By rotating the spindle in an electrolytic bath a thin coat-
ing is precipitated, which is smoothed and provided with a sepa-
rating layer. Then a further metal coating is precipitated in the
bath and the manipulation continued in this manner until the de-
sired strength of deposit is reached. In case that a still greater
strength of the metal coating is desirable it can be obtained by
having direct contact of the separate metallic layers, which is done
by drawing well placed lines through the separating layer so that
at these points the succeeding metallic deposit comes in contact
with the underlying metallic layer, without, however, sensibly
affecting the flexibility of the whole.
Xn. MANUFACTURE OF PARABOLIC
MIRRORS.
The expensive operations required for the production of exact
parabolically curved mirrors has led many investigators to at-
tempt to produce such mirrors electrolytically in a cheaper man-
ner.
FBOCESS OF THE ELMOBE GERMAN AND AUSTBO-HUNOABIAN
METAL COMPANY, LIMITED, AND P. E. PBESCHLIN.
Amongst the important attempts which have been practically
tried we may mention the process of the Elmore German and
Austro-Hungarian Metal Company, Limited, and P. E. Presch-
lin.i
Patent Claims.
1. An arrangement for the manufacture of saucer-shaped ves-
sels electrolytically characterized by placing the cathode, corre-
sponding to the form of the vessel, upon an inclined axle, in order
thereby to place the driving gear and bearings of the axle outside*
of the bath, while parts of the cathode dip into the bath.
2. In the arrangement of the apparatus described in Claim i a
smoothing tool pressed by a spring which by means of wheels and
levers moves slowly in the plane of the axis of rotation of the
cathode in order to act upon all parts of the concave vessel.
PROCESS OF COWPEB-COLES.
Sherard Osborn, Co:wper-Coles and the Reflector Syndicate,
Limited,^ have solved the problem of manufacturing perfect mir-
rors for reflectors in a most characteristic mannei
Patent Claims,
I. The process for the manufacture of hollow minors charac-
terized by covering over a mould with a layer of wax, precipita-
ting upon this layer silver by a chemical process, afterwards pre-
I German Patent 71.831, April 6, 1893.
« German Patent 89,249, Feb. 26 1896 ; English Patent 5 600 March 16. 1895.
MANUFACTURE OF PARABOLIC MIRRORS IO9
cipitating upon the silver a layer of palladium galvanically, after-
wards also galvanically precipitating a further coating of copper
or another suitable metal, while rotating the form, and heating
the mirror after removing from the form in order to alloy the
palladium with the silver or treating the mirror with a solution
of potassium cyanide or the like in order to remove the silver.
2. In the process described in Claim i, the production of the
wax coating by painting with a solution of wax in benzine or any
other volatile solvent.
3. In the process of Claim i, rubbing and polishing the silver
coating before the galvanic precipitation of the palladium.
4. In the process of Claim i, the use of a form consisting of a
mixture of sulphur and graphite in which the latter material is
somewhat in excess.
The Forms and Their Manufacture,
Forms are made out of glass, wax, metal, or any other suitable
material which may be provided with a thin coating of silver. It
must be noted that the silver coating can be directly precipitated
upon the wax ; all other kinds of forms must be first coated with
a layer of wax before they can be silvered. The wax solution is
best as a solution of bees-wax in benzine, because the latter vola-
tilizes very rapidly and leaves the dissolved wax upon the form in
an unusually uniform layer. When this coating has become suffi-
ciently solid it is rubbed with a piece of chamois leather until it
has a high polished surface. This treatment is quite necessary
with glass forms since the small flaws found upon the surface of
the same will easily become larger by use, and they cause the
formation of still larger unevenness if they are not carefully cov-
ered over.
The silver precipitate produced in the chemical way is likewise
rubbed and polished with leather, whereby at the same time the
silver is loosened from the support. The silvered form is then
covered over with palladium in a galvanic bath consisting of
Palladium ammonium Chloride 0.62 per cent.
Ammonium chloride i.oo **
The bath is worked at a temperature of 24.^ C, using graphite
plates for anodes. The current density used is 0.027 ampere per
I lO MANUFACTURE OF METALLIC OBJECTS
square decimeter, the bath tension corresponding to the feeble
concentration of 4 to 5 volts.
The silver bath for coating the wax consists of
Silver nitrate 0.5 per cent.
Caustic potash 0.5 *'
Glucose 0.25 **
The form being thus prepared it is placed in a copper bath con-
taining :
Water 83 parts
Copper sulphate 13
Sulphuric acid 3
At starting a high current density is used up to 10 volts ten-
sion. The palladium layer is covered over very quickly with cop-
per and then the current density is decreased. During' the precipi-
tation of copper the form is continually rotated and the precipi-
tate may be smoothed by smoothing tools while it is forming.
Loosening of the Precipitate,
When the copper backing has reached the desired thickness the
form with its silver, palladium and copper precipitates is removed
from the bath and warmed to between 65° and 95° C, whereupon
the layer of wax melts and the form is separated from the pre-
cipitate. The precipitate is now further heated in order that the
silver may alloy with the palladium, or the silver coating is treated
with a solution of potassium cyanide or some other solvent of sil-
ver which does not attack the palladium.
In the first case the mirror will have a surface consisting of a
palladium-silver alloy which has the advantage that the palladium
is not so easily tarnished as the silver while the silver gives to the
precipitate a high lustre.
If, on the other hand, the silver is completely dissolved away
then a pure palladium surface is left, which likewise shows a high
lustre because it was produced upon a polished silver background.
Instead of precipitating the palladium upon the silver and copper
upon the palladium the copper can be precipitated immediately
upon the silver, and the palladium or any other non-tarnishing
metal precipitated upon the silver after the removal of the mirror
from the form.
MANUFACTURE OF PARABOLIC MIRRORS III
If the form is of metal, for instance of iron, with a layer of cop-
per silvered upon its surface, the palladium can at once be pre-
cipitated upon its surface without first coating it with silver; the
copper can also be precipitated immediately upon the form having
a silver coating.
Chromium may serve as a substitute of palladium or silver in
the manufacture of spherical mirrors.
The economy of the manufacture of mirrors by the above de-
scribed process consists principally that the reflectors do not need
tedious polishing but at the most need a treatment such as is
called in practical galvanoplasty, "Hand coloring." At the same
time the mirror surfaces are produced nearer to the mathemati-
cally correct shape than by the previously used process. Finally
the new mirrors are less sensitive to deformation by uneven heat-
ing and are not so easily injured by rough handling.
If desired the reflectors can also be made hollow so that water
or any fluid may be run through them to avoid too high heating
when in use or the alteration of shape which is caused by heating
may be compensated for by unequal thickness of the walls of the
reflector.
The forms are made preferably of a mixture of sulphur and
graphite, with the latter somewhat in excess, and may be cast in
glass moulds.
The palladium or palladium alloy can also be placed upon the
mirror in the form of an amalgam, for instance, by a similar pro-
cess to that used in gilding with mercury.
Apparatus.
The patent specification describes a series of apparatus particu-
larly for the carrying out of the electrolytic part of the work.
Fig. 55 shows a longitudinal section of an electrolytic bath on
which the copper background of the mirror is deposited.
Figs. 56-58 show the details of the apparatus.
Inside the box A is the form B serving as cathode and provided
with an edge B^ and arranged so as to be removable from but
resting upon the square upper end of a vertical shaft b, which is
rotated by conical wheels beneath through the journal C and the
packing box D. The anode E has an arched form corresponding
H2 MANUFACTURE OF METALLIC OBJECTS
to the form B and may be hung in the eye e in any convenient
manner. It is covered inside with a woven cover, for instance of
unbleached cotton, in order that any small particles from the
anode may not fall upon the form. During the rotation of the
form B the roller G^, which is coupled by an arm Gj to an arm
Gi, produces pressure upon the copper precipitate. This latter lies
removable in the yoke G, held there by the eye G^, the end being
movable backwards and forwards by the endless screw F', placed
Fig*- 55. 56- 57- 58.
upon an axle F. The axle F is fixed upon the box A by the bear-
ings f and carries at one end three disks p, f, f, of which the
middle one is loose and driven by one crossed and one straight -
belt. The belt fork, G°, which governs the position of both belts,
is fastened to a bent lever, G', by means of a rod, G*, and in the
same manner as the upward directed arm, G° moves the nut G
upon the rod, G", which is fastened above the shaft F.
MANUFACTURED OF PARABOLIC MIRRORS
113
By the arrangement described the direction of rotation of the
shaft F is periodically automatically reversed, since the nut G
moved in one direction by the screw F^ strikes against the end of
the bent lever, G^, with its arm, G*^, and moves with it until the
telt reversing motion is operated; whereupon the screw moves
in the opposite direction until the arm, G^, strikes against the
other end of the bent lever and again reverses the belts. The
arm, G^, moves with the motion of the nut, G, since it passes into
the slit, E^, of the anode E, while the roller, G*, moves up to the
apex of the form.
In order that the roller, G*, may regulate automatically the
pressure which it exerts against the top of the copper precipitate
corresponding to the circular part of the mirror upon which it
works, the arm, G^, is provided with a weight, H, which is car-
ried in a slit, g, and has an automatic motion imparted to it by the
arrangement shown in Figs. 56-58. The threaded part, F^ of the
shaft F engages the worm wheel, g^, which is keyed to the nut G,
and upon whose axle a roller ,^.^, alternately winds and unwinds a
chain or a string, g^, which is carried over an idler, g^, to the rod
of the balance weight, H, and thus moves it up and down as the
shaft, F, is turned in one or the other direction.
In Fig. 59 there is shown a somewhat different arrangement.
The cupola-shaped anode is replaced by two plate-like forms.
Two rollers, G*, are placed diametrically opposite each other in
the arms P and P loaded by the weights Pjv and Px. Both arms
114
MANUFACTURE OF METALLIC OBJECTS
are connected to the nut, P, which is moved up and down by the
vertical spindle, I, whereby the rollers, G*, approach almost to
touching each other at the apex and can separate towards the
periphery of the form. The nut, P, is hindered from turning by
the rod P, which may be arranged to be revolvable around the
drum, P, fixed upon the box A, so that the whole arrangement
may be swung to one side if the form b is to be taken out.
FiR. 60.
Fig. 61 shows another arrangement which can be used in place
of that in Fig. 59. The bent arm J is fastened to the side of the
containing vessel at J^, its upper end being held by an adjustable
brace, J^ ; its outer form corresponds to that of the mould B. Two
Fig. 61.
chain rollers, J-' and J*, are fastened to the ends of J, one of which
is provided with a driving sheave, and carry the chain, J°, upon
which are a number of rollers, J®, replacing the pressure roller,
G*. The arm J carries a guide for the chain and the pressure
MANUFACTURE OF PARABOLIC MIRRORS
IIS
rollers, J®, roll one after the other upon the form B, each de-
scribing a path from the periphery to the crown of the mould.
The carriers for the roller axles are so arranged that they can
be easily removed if the mould or the completed mirror is to be
taken out. The pressure rollers can also be moved by little fin-
gers or eccentrics, especially if the distance between the periphery
and crown of the mould is divided between several rollers.
A suitable arrangement is also that of inclining the shaft B,
and giving the box an angular cross-section in such manner that
one wall is at right angles to the shaft. The shaft B can also be
made telescopic and provided with a screw arrangement or the
like to allow of the form being lifted out of the box.
The observation of the precipitate is facilitated if the vessel is
connected by means of a hose with another vessel so that by the
raising or lowering of the latter the solution can be run in or run
out of the precipitating box.
Pig. 62.
Fig. 62 shows an apparatus suitable for the precipitating of a
galvanic coating of palladium or chromium upon the form. The
pan K is heated with steam and lined with lead or some other
metal suitable as an anode and which will hold the palladium
solution. It is carried by a spindle L, which since it is prevented
from rotating by the steam pipe may be raised or lowered by
Il6 MANUFACTURE OF METAIXIC OBJECTS
means of the nut M turning in the bearing O, so that the form B
fastened by means of hooks N^ and the chain N^ to the supports
N, can be dipped into the solution by the raising of the pan K or
left out of the solution by the lowering of the same. With this
arrangement a comparatively small quantity of palladium solu-
tion is necessary for constituting the bath.
Instead of the forms as shown in Figs. 55-61 with their bent
surfaces arranged on top, these may be inverted and driven by
vertical shafts from above. In these cases the round anode and
the pressure rollers can be dispensed with and replaced by the
pressure of the friction between the surface of the rotating form
and the electrolyte.
This process is carried out on a large scale by the "Searchlight
Syndicate, Limited/'^ who manufacture parabolic mirrors and
locomotive headlights. Several reflectors are precipitated and
taken from one form without the latter needing polishing. The
process is not expensive. For instance, the silver deposit does
not weigh more than 0.059 niilligram per square inch and is
0.0000034 inch thick. The cost of this deposit is not more than
23^ to 4 cents per square inch.
1 The Electrician, I«ondoii, (46), 578 to 580.
Xm. MANUFACTURE OF TUBES.
In the processes coming under this heading the most necessary
items are suitable arrangements to separate the metal deposited
upon suitable mandrils from the same, and to obtain an outer sur-
face smooth and free from excrescences.
Elmore has succeeded in this line quite brilliantly, producing
on a larger scale tubes of the most varying diameters and lengths.
For the quick production of tubes of small diameter, J. O. S.
Elmore^ uses the following apparatus suitable for continuous
working (Figs. 63-66) :
The bath is contained in a trough shaped vessel A, having a
[/-shaped section and divided by partitions into a number of
chambers through which the core D passes. In some of these
/f F
D A
Figs. 63, 64, 65, 66.
subdivisions the electric current is led to the core by springs C
and the precipitate is rubbed by polishing stones B. The anodes
are only placed in such compartments which contain neither con-
tact places or smoothing tools, thus avoiding the plating of these
parts.
The trough is longer than a single core which latter extends
between two rods of non-conducting material such as wood or
the like. It is passed through the end of the box by means of
stuffing boxes H.
1 German Patent 95,857, July 2, 1897 ; English Patent 7.222, April 2. 1896.
ii8
MANUFACTURE OF METALUC OBJECTS
The electrolyte flows continuously through the apparatus and
the trough is covered, with a closely fitting cover R in order that
the electrolyte may be conducted through it under pressure. The
core is rotated during the action of the process and rnoves in and
out through the chambers.
Patent Claims.
I. The apparatus for the manufacture of tubes by electrolytic
deposition of metal, characterized by using a box A divided into
chambers with a rotating core or mandril D, serving as a cathode
Fig. 67.
and movable backwards and forwards in the direction of its
length and provided with contact springs C and smoothing tools
e, in some of the compartments, and with anodes f of the metal
to be precipitated surrounding the anode in the alternate com-
partments, in such manner that the electrical current passes
through the contacts C and the anodes, decomposing the electro-
lyte flowing through the compartment and depositing the metal
upon the core.
MANUFACTURE OF TUBES
119
2. The form of apparatus for carrying out Claim i, in which
a series of vessels A have their cores or mandrils insulated from
each other by the insertion of non-conducting pieces, and the
anode of each box is in electrical connection with the contact
springs bearing upon the mandril of the next following box, thus
making it possible to remove from time to time the last mandril,
to move up the following mandril into the last box and to place
a polished mandril in the first box and so to produce tubes con-
•
tinuously.
Old Process of i8po.
The old process* for the manufacture of tubes had the following
patent claims.
I. The process of producing copper tubes electrolytically con-
sisting in placing the iron mandril first in a copper cyanide bath
and coating it with a layer of copper which is afterwards oxidiz-
ed and subsequently placed in an acid solution of copper sulphate
for the purpose of further precipitating and compressing of the
copper ; using in the latter bath copper plates with granulated cop-
Fig. 68.
per thereupon as anodes, and rotating the mandril serving as
cathode, while at the same time the precipitated layer of copper is
1 German Patent 59,933, Nov. 19, 1890 ; English Patent 18,896, Nov. 21, 1890 ; American
Patent 464,351 ; French Patent 209,602,
120 MANUFACTURE OF METALUC OBJECTS
compressed by an oscillating polishing tool, and finally subjecting
the mandril thus coated to the influence of pressure rollers in such
manner that the copper coating is stretched in the direction of its
circumference, and thus loosened from the mandril.
2. The modification of the process of Claim i, consisting in
afterwards plating a certain thickness of copper, in order to form
separated concentric copper tubes one over the other.
3. For the carrying out of the process of Claim i, the use of
two parallel series of electrolytic baths with mandrils therein, the
rotation of which is accomplished by means of an intermediate
shaft, while the backwards and forwards motion of the polishing
tools is produced over all the mandrils simultaneously by means
of a reversing pulley and coupling actuated by a finger fastened
upon a spindle of the first pair of mandrils.
4. The carrying out of the process described in Claim i, con-
sisting in the loosening of the copper tubes from the iron mandril
by placing the mandrils between concentric rollers and slowly
rotating the same while at the same time pressure rollers T^, T^,
T^, normal to the tube exert pressure upon the copper tube and
are movable in the direction of the length of the tube.
The Polishing Tools.
The Elmore process lays particular stress upon the construction
of the polishing tools and they patent several different forms. The
Elmore German and Austro-Hungarian Metal Company, Lim-
ited, makes the smoothing tools in the shape of a wheel rotating
upon an axis, which is approximately perpendicular to the ro-
tating mandril. The wheel is moved the length of the mandril
backwards and forwards, and at the same time has a rotary mo-
tion. As soon as the surface of the precipitated metal becomes
uneven the smoothing wheel must have a radius which is smaller
than the smallest radius of any of the depressions in the coating.
The wheel can then enter into any cavity and work its surface.
Fig. 68 shows a section through the bath in which the wheel-
formed smoothing tool acts upon the rotating mandril M. A is
an arm provided with a screw spindle which moves it backwards
and forwards parallel to the axis of the mandril. The smoothing
tool is then moved backwards and forwards upon the metallic sur-
manufacture: of tubes 121
face of the deposit. A clamping screw fastens the second arm B
to the bracket A by a slot in the latter and the rod R, which is
movable by means of the screw S. The rod R is fork-shaped and
carries the wheel W, which with one edge runs upon the surface
of the mandril. A rubber band C passing around the rod R and
into the teeth upon the arm B, serves to press tne wheel W against
the circumference of the mandril.
Since the arm B moves back and forth upon the mandril the
wheel W passes along the latter and continually forces its edge
to the smoothing of new deposits. When one of these edges is
dulled the wheel is turned around the axle of the rod R in order
to use the other edge. A positive motion can be given to the wheel
W by means of a wire or a cord running around a small pulley
upon the same axle and so give to the wheel a quicker or slower
motion than it would naturally acquire from its contact with the
copper tube. The driving wire or cord is stretched the whole
length of the bath and is kept tight by a weight so that it con-
tinually presses against the small pulley and thus rotates the wheel
W.
Patent Claim.
An arrangement for the smoothing and compressing of metals,
which are being precipitated upon a rotating mandril character-
ized by using a wheel of agate or a material of approximately
equal hardness which is pressed against the mandril with one edge
while the latter is rotated and simultaneously moved backwards
and forwards along the tube.
An alteration in the manner of smoothing^ is obtained by giv-
ing to the smoothing tools an additional motion lengthwise.
Patents of Elmore.
Further improvements in the Elmore process are contained in
the following patents:
English Patent, 2,618, February 14, 1889.
German Patent, 65,808, April 12, 1891.
German Patent, 72,195, April 6, 1893.
German Patent, 71,811, April 14, 1893.
German Patent, 77,745, March 4, 1894.
1 German Patent 67,947, Sept. 29, 1892 ; English Patent 17,631, Oct. 15, 1891 ; American
Patent 503,076.
122 manufacture; of metallic objects
Literature.
The following articles contain additional information:
El. (1888), 22,47.
Lum. el. (1888), 30, 435 ; 3i, 280; 32, 579.
Engineering (1898), No. 1714, William Brown.
El. Rev. (1891), 28, 449 and 476. Watt.
Engineering (1890), 50, 21 and 46. A. W. Kennedy.
Operation.
In the manufacture of 1,000 kilograms of copper tubes there
are used 1,170 kilograms of coal, for a bath tension of 0.5 volts,
corresponding to a cost of about $1.75.
At the works of the Elmore Company in Hunsled, near Leeds,
there are four dynamos each of 37.5 kilowatts and furnishing 50
volts and 750 amperes.
These works use Chili copper granulated by running into
water. The plant contains 60 baths in series each of the dimen-
sions, 3 meters long, 0.8 meter wide and i meter deep. The bath
tension is 0.9 volt. The precipitate grows slowly so that working
night and day a copper tube of 0.3 millimeter thickness requires
6 days for its production. In the works of the German Elmore
Company in Sladern, on the Sieg, there are 1,200 HP., of which
550 are used. The dynamos furnish 1,200 amperes at 50 volts.
'The works can produce 35 tons of tubes weekly. Atmer gives
some exact figures of the profits of this process using 94 to 96 per
cent, blister copper. The granules are used in a layer 20 centi-
meters thick upon the anode plate. The tanks are arranged in
long double rows in series. Every two rows of tanks possess a
common shaft serving for the driving of the mandrils. Between
the tanks of each row are cast iron slides lengthwise of the boxes
and an automatic mechanism moving in slots in these guides pro-
vides the necessary motion for the smoothing tools.
The copper tubes increase in thickness 0.03 of a millimeter be-
tween each passage of the agate smoothing tools, thus obviating
the precipitation of crystalline copper. The advantage of the
smoothing tools is in the fact that using them, current densities
up to 1 ,000 amperes per square meter can be employed. The nor-
mal current density on the other hand is scarcely 200 amperes.
MANUFACTURE OF TUBES I23
The normal length of the tubes is three meters and the process
must never be interrupted during the formation of a tube.
The tube being ready the box containing it must be cut out of
the circuit, and the solution run into a tank at a lower level in
which the anode slime is allowed to settle.
Loosening of the Tube.
The loosening of the tubes which are made up to diameters of
1.6 meters is either accomplished in the previously described waj
or in case copper mandrils are used by substituting for a period of
half an hour, for the polishing agate, as long as the precipitate
is stiil quite thin, an agate roUer which rolls upon the precipitate
with a>moderate pressure and thus loosens it from the mandiU.
Large copper sheets can be obtained by the Elmore procei:" by
cutting a cylinder parallel to the axis of the mandril. The table
in the Appendix gives data concerning the weight of tubes thus
produced.
PEOCESS OP THE FRENCH COPPER SOCIETY.
The Societe des Cuivres de France' produces compact tubes
electrolytically.
The smoothing and compressing is attained in this process by
using in place of the agate tools of the Elmore process the pres-
sure of two rollers moving upon each other.
Fig. 69.
Apparatus.
The apparatus used for this precipitation is shown in Fig-i 69-
71. The container a holds the electrolytic bath and has the roll-
formed cathodes b and c contained in any suitable number in the
; English PfltenI is,6So, Dec. 5, 1*94; American
124 MANUFACTURE OF METALLIC OBJECTS
vessel. The lower roller b has its axle supported by insulating
blocks d, which are also provided with guides e for the spindle of
the upper roll c.
The lower roll is driven by a belt pulley f and communicates
its motion to the upper roll c which is held loosely in the bushing
in order that it can change its position according to the increase
of the thickness of the precipitate. The rolls are kept together
either by their own weight or by springs. At the beginning, how-
ever, the rolls should not touch because such would injure the
graphite coating upon them. In order, therefore, to provide con-
tact between the rolls from the start they are provided with cop-
per disks at their ends having a slightly larger diameter than the
rolls so that these come in contact with each other and leave the
rolls thus uninjured.
Fig. 70. Pi»- 7'.
When a precipitate of a certain thickness has formed the cop-
per rings alluded to are taken off and the rolls allowed to come
in contact with each other. The current is carried to the rolls by
brushes h touching the roll c. The rolls, instead of being ar-
ranged as in Fig. 69, can be arranged in any desired number, as
in Fig. 71.
The sectional shape of the anodes k I, as well as their material,
is determined by the shape of the cathodes and by the material to
be deposited.
The current entering at m and h precipitates the copper uni-
formly upon the rolls b and c, and is cut off as soon as the de-
sired thickness of deposit has been obtained.
MANUFACTURE OF TUBES 125
Large Tubes.
In precipitating larger tubes according to this process, two or
more smaller rolls can be used in order to avoid too large dimen-
sions of the tanks and these rolls are arranged as shown in Fig.
71. The current is carried into one of the rolls Z? by a brush h,
and passes to the rolls c^ and c^. Thus tubes of large or small
diameter may be produced simultaneously in the one vessel.
As in the Elmore process the tubes can be either used as such
or by slitting and straightening as copper sheets.
Patent Claims,
1. The process for the electrolytic deposition and simultaneous
compressing of copper and other metals characterized by the use
of two or more rotating rollers as cathodes in such manner that
they exert pressure upon each other in order to compress the metal
precipitating upon them.
2. The apparatus for carrying out the process of Claim i, con-
sisting of a vessel a, in which adjacent or superposed rolls, c, or
b, c^, c^, always in light contact with each other, are arranged as
rotating cathodes, their distances from each other being auto-
matically regulated according to the thickness of the metal de-
posit, and the anodes have any suitable form.
PROCESS OF DUMOULIN.
The Dumoulin process^ was discovered in 1895, ^^ ^^ attempt
to find a suitable method of avoiding the excrescences upon an
electrolytic deposit. Dumoulin observed, as many others have
likewise, that the deposition of metal occurred principally on the
projecting parts of the cathode and that these excrescences were
the principal reason that ordinary cathode copper cannot be rolled.
If the projecting excrescences are, however, insulated until the
surrounding part has reached the same thickness, or if a dia-
phragm is interposed between the excrescences and the solution,
then the precipitation will finally arrive at a point where again
the smooth surface begins to be deposited upon.
Dumoulin obtains this hindering of precipitation upon the ex-
crescences by bringing the cathode cylinder into contact with an
1 German Patent 84,834, April 9, 1895 ; English Patent 16,360. Aug. 31, 1895; Zeitschr. f.
Elektrochemie, a, 509.
126
MANUFACTURE OF METALLIC OBJECTS
insulating or adhesive material placed upon a porous body. The
coating of the body with insulating material occurs only upon the
projecting parts, thereby hindering further deposition upon them.
Fatty substances are the most suitable as coating material or such
bodies which naturally contain fatty substances or with which
such can be mixed. Amongst these may be mentioned, animal
membranes and extracts from them (albumen, fibrin, etc.), skins,
muscles, entrails, and the like. In general, any sort of material
may be used which is saturated with a fatty or oily insulating
body. The principal requirement is always that the body is pli-
able and does not fall to pieces in the machine.
In the special treatment proposed by Dumoulin, the following
points play an important part:
I. The contact surfaces of the cathode and the rubber holding
u
Fig. 72.
the insulating material.
2. The pressure of the rubber.
3. The velocity of motion of the cathode or of the rubber.
4. The current density.
MANUFACTURE OF TUBES I27
The rubber is given a slight longitudinal motion in order that
all parts of the cathode can be equally treated ; the movement of
the rubber is independent of the cathode cylinder.
The Apparatus.
Fig. 72 shows in section the principle of the apparatus ; it shows
more particularly a longitudinal section of the apparatus for the
manufacture of large tubes and sheets. The core m, upon which
the cathode is placed, is in this case made short. At the ends it
has a pulley g of insulatating material, and in the recesses of the
mandril, there are rectangular bearing pieces h, which are con-
nected with the spindle b. The latter passes through hollow bear-
ings f, which are fastened by stuffing boxes to the vessel A. The
electric current is led in by contact brushes /.
FiR- 73.
For larger tubes the mandril is of brass or bronze, for small
tubes of steel. The mandrils are pohshed or greased before they
are put mto the baths. In order that ail points on the surface may
be equally coated with the fatty material the rubber is moved par-
allel to the length of the cathode cylinder by means of a screw.
This motion must be adjusted to the velocity of rotation of the
cylinder and be uniform.
128 MANUFACTURE OF METALLIC OBJECTS
The Rubber,
Fig. 73 shows the rubbing apparatus for applying the fatty
material. The latter is placed in it and pushed against the cathode.
The rubbing surfaces are arranged along side of each other upon
a shaft T, (Fig. 72), upon which they are moved by a worm gear
C. They are movable upon the shaft T, but not longitudinally.
Dumoulin has the opinion that the insulating material can als<>
be put directly in the bath ; in this case the rubbers would have
the function only of passing over the cylinder and rubbing the in-
sulating material upon the projections of the cathode. In sucii
cases brushes of silk or the like would suffice.
Loosening of the Tubes,
The loosening of the tubes is attained by slowly warming them,
whereby the mandrils separate from the precipitate; if this is
insufficient, hydraulic pressure is used.
It is of importance for the process that the temperature does not
exceed 16° C, in order to insure the permanence of the animal
membranes used. The temperature can be kept down by the
blowing in of air and circulation of the electrolyte, at the same
time iron and organic compounds would be thereby oxidized.
Patent Claim,
The process for the manufacture of uniform electrolytic metal-
lic deposits characterized by placing upon the cathode during the
precipitation insulating materials in such manner that only the
projecting parts of the precipitate receive a coating of the in-
sulating material, the process being in this respect similar to the
inking of type by ink during printing, by which treatment and in
which process also the insulating material is oxidized in the bath
and can be removed by a rubbing arrangement used for applying
the insulating material as soon as the projecting parts have dis-
appeared and become uniform with the whole surface of the
cathode and for that reason do not need longer the application
of the insulating material for the retardation of the deposition
upon them.
MANUFACTURE OF TUBES 1 29
Operation.
The Dumoulin process is carried on at the Brunoy Works, near
Paris, and at Widnes, England, by the Electrical Copper Com-
pany, which has a capital of $2,500,000.^
In the latter works there are 5 dynamos furnishing a total cur-
rent of 1,300 amperes at 75 volts. The electrolyte used is a solu-
tion containing 40 per cent, of copper sulphate with 7 per cent, of
sulphuric acid. The tanks are wooden vessels with lead linings
and the electrolyte circulates through thirty in series. The man-
drils are copper cylinders 3.6 meters long and 40 centimeters in
diameter, which dip half way into the electrolyte. The anodes are
of cast blister copper in the shape of a U. The current density is
3.5 to 4 amperes per square decimeter and the bath tension 1.6
volts.
1 Wm. Brown, Kl. Rev. (1898), 43, 561, 663. Engineer, Oct. 2j, 1898.
XIV. ELECTROLYTIC ETCHING.
Practical electroqjiemistry has not only utilized the cathodic
reactions of electrolysis, but ^Iso anodic reactions in order to pro-
duce useful articles of the most different kinds. The process of
dissolving metals at the anode which is partially protected or
covered with a design, has been known for a long time, and some-
what recently the process of Joseph Rieders of electrolytically
etching dies deserves to be mentioned more at length. This pro-
cess is called by the inventor electro-engraving, and is described
in full in the next chapter.
Concerning the ordinary etching processes, such solutions are
used as electrolytes which contain free anions, such as are able
when discharged against the metal of the anode to form an easily
soluble salt therewith, but which do not show a particular tend-
ency to attack the anode when current is not passing. The choice
of the electrolyte should not be difficult to the chemist or electro-
chemist. For copper or its alloys dilute sulphuric acid or alka-
line salts, such as potassium sulphate or potassium nitrate; for
iron and zinc, sodium sulphate or ammonium chloride, for silver
potassium cyanide in solution, etc.
The procedure in electrolytic etching consists in coating the
object to be etched with lacquer, melted stearine or some other
insulating material, laying bare the parts of the metal to be en-
graved or etched, cleaning the latter with alcohol, benzine, lime,
or any suitable cleaning material, but in such a manner that the in-
sulating coating is not injured. The article thus prepared is used
as an anode in the etching bath. For cathode a metallic or car-
bon plate is used. On closing the circuit the metal is dissolved
at the exposed places, while the covered places remain unat-
tacked. By regulating the current it is possible to etch more or
less deeply or to accelerate the process.
This method has many applications ; so there can be imagined
an imitation of deep engraving processes carried out by printing
a sample upon the metallic surface with a grease color, in which
^I^ECTROLYTIC ETCHING
131
case the fat in the color serves as a coating. The design which is
to be engraved remains uncovered. The printed surface is then
covered with powdered asphalt or some sort of a resin, some of
which sticks to the greasy places while it can be blown away from
the unprinted places. The object being then warmed to the melt-
ing point of the resin or asphalt, the latter melts, and after cool-
ing serves as a protective coating, while the uncovered metallic
surfaces are being etched, so that in this way a deeply cut design
is obtained. It is possible, further, to deposit in the depressions
so etched a precipitate of a metal of different color from the
ground mass, and upon polishing the whole plate to have a beau-
tiful piece of inlaid work.
In this manner, also, may be produced, without difficulty, plates
and rolls for caHco printing and embossing of paper, cloth, leath-
er, etc., which have been formerly made at great expense by en-
graving.
r^ai
V
-4-
" !■ " " ■' '''
"«3^
W^
6'
1 ii II
" ^^ " "
^ojoQOoagjiaioa
*94#=§
7 ' 11 ■' I' " " " " " " " ' " !' ■' " "-TT-f : : 3 :
<5t-
/t'
/n o
^
Fig- 74-
-. / f 6*
c4JU ^ I c
Fig. 75. Fig- 76.
BURDETTE'S PROCESS.
Burdette^ patented a process for the galvanic etching, suitable
for producing figures, monograms, numbers, and other designs
upon cutlery, tableware, etc. Figs. 74-76 show his apparatus.
1 German Patent 83,615, Feb. 26, 1895 ; Zeitschr. f. Klektrochemie a, 359.
132 MANUFACTURE OF METALUC OBJECTS
The working table a, usually of wood, has a holder b for re-
ceiving the articles to be etched. The holder consists in this case
of rods b^ b^, with shallow depressions in their surfaces for re-
ceiving and holding the pieces. Since the process is particularly
intended for the etching of cutlery, although it is applicable for
the etching of all other kinds of metallic objects, its application
to table knives is taken as an illustration.
The rods b^ b^ are of metal and insulated, and lie upon strips
with the insulating material fastened to the conductors d. The
detachable metallic conductor is arranged at some distance above
the point where the drawing or the like is to be etched. In the
apparatus shown in Fig. 74 these conductors are of small copper
strips carried by a rod f. The rod / is fixed to the arm g, which
projects from the stand h, fastened to the slide i. The slide is
fastened to the conductor k, which is movable in relation to the
row of knives by means of a screw spindle /. This form of ap-
paratus is suitable for the treating of a number of pieces, such as
knives, to produce the same mark or design upon all. For other
pieces any suitable form of slide can be used. It is necessary
that the conductor remains a certain time immediately above the
surface of the piece, being treated in order to etch in the mark
by the action of the electric current.
The conducting wire m goes from the positive pole of the
source of electricity through the rods &^ b^, upon which the arti-
cles to be etched are laid, while the conducting wire n from the
negative pole is connected with the rod f carrying the conductor e.
In a suitable place, for instance, along the front edge of the table,
there is a guide p, upon which is fasteened a movable sliding
block />^, which carries an adjustable arm with the stamp q. This
stamp when pressed down upon the surface of the knife-blades
prints upon them the design to be etched, the blades having been
previously coated with a special material : the surface of the stamp
is cleaned with a solution which will be described. After the
articles have been stamped one after the other, the stamp is moved
sideways, the slide forwards, and the conductors arranged direct-
ly above the imprint of the stamp upon the blades.
The etching is completed by using a current which acts upon
the imprinted design, but leaves untouched the background.
ELECTROLYTIC ETCHING I33
The material for the protecting coating consists of
Naphtha i liter
Carbon bisulphide 125 grams.
Pulverized resin 2000 grams.
Cupric chloride 1500 grams.
A thin layer of this coating is placed upon the surface, the
stamp washed off with a weak solution of caustic potash, and then
pressed upon the coated surface. The articles are then washed
with water and the imprint of the stamp with a weak solution of
ammonium chloride. The articles are then at once subjected to
the electrolytic etching. The imprint of the stamp is etched upon
the metal because the place stamped is in conducting connection
with the current used. The ammonium chloride used in this pro-
cess can be replaced by common salt.
Applications,
The process, as described, takes only a short time. When the
etching is completed the knives are taken out, dipped into a solu-
tion of caustic potash or soda in order to dissolve off the coating.
The knives are then ready for further treatment.
The process described allows of etching to a sufficient depth to
show quite clearly the design of the stamp.
HALL AND THORNTON'S FBOCESS.
Hall and Thornton^ have invented another method of applying
anodic action in order to produce points upon metallic rods.
Many metals are injured by the cutting, turning, hammering
or rolling which they must undergo in order to put them into the
desired shape.
Unavoidable heating of surfaces which are being worked can
easily draw the temper of steel pieces. To avoid this some fac-
tories have replaced grinding by an electrolytic bath in which the
articles to be worked are used as anodes in order to be thus re-
duced to the desired thickness. In the process being described
articles of uniform or non-uniform dimensions may be treated
and the desired removal of material is controlled by raising or
lowering the level of the electrolyte or by the corresponding sink-
ing or raising of the articles. The articles treated are awls, need-
1 German Patent 87,845, Aug. 30, 1695 ; see also Zcitschrift f Elektrochem ie 3, j 3
'34 MANUFACTURE OF METALLIC OBJECTS
les, surgical instruments, fish hooks, umbrella ribs, rapiers,
swords, spokes for bicycles, forks, etc. The patent describes the
following apparatus for the carrying out of this process.
Apparatus.
Fig. 77 shows the apparatus for the treatment of a series of
wire rods, which are to be given a tapered form by being grad-
ually lifted out of the solution. Fig. 78 is a plan of the arrange-
ment of Fig. yy. Fig. 79 shows a tapered metallic rod produced
Fijta. 77, 78, 79.
by this process. Fig 80, the same before being treated. Fig. 81
is a cross-section on a large scale of the connections for one of the
ends of the rod.
t=^=aRSO
The holder contains the electrolyte or the dissolving fluid b,
and metallic zinc is added to the same, if necessary ; Oi is a stop-
cock for running off the solution, c and d are conductors of the
current. The conducting pieces, c^ d,^ carry the current from the
negative or the positive pole of the electric generator to-c and d,
while the contacts d^ are connected to the rods d, their ends lying
upon insulating pieces, d^. Upon the rods d are yokes tf, to which
are fastened the upper ends of the hanging rods /, which form
ELECTROLYTIC ETCHING I3S
the anodes, while the negative rod c, which is likewise insulated
at one end is in connection with a block of carbon e, which forms
the electrode. The electric current enters the solution at the
anode rod e and leaves the solution at the carbon cathode.
When rods or wires of iron are to be used the solution becomes
saturated with that metal which either deposits as slime or is
deposited upon the cathode. Instead of using only one carbon
block as cathode a series of such blocks may be used connected
with the negative conductor of the system.
Fig. 82 shows the invention applied to the pointing of metallic
pins, needles, or the like. Fig. 83 is a plan of Fig. 82. Fig. 84
shows a needle before being pointed. Fig. 85 shows how needles,
having eyes, can be hung in order to be pointed by the process.
a is the containing vessel, a, the rim off cock, and / the articles
to be pointed by being gradually drawn out of the solution b. d
is a positive conductor and holder or the pieces, while e is the
cathode which is hung to the other conductor c.
Fig«. 81. 83, S4, 8s. 86.
Fig. 86 shows a sectional diagram of the apparatus applied
to simultaneously carrying out the process in two vessels in one of
which the fluid rises, while in the other it sinks.
136
MANUFACTURE OF METALLIC OBJECTS
Fig. 87 shows an apparatus in which the articles to be pointed
are gradually lifted out of the solution, the level of the fluid being
kept constant.
Figi. 87. B8, S9, 90, 91, 91, 93, 94.
a is the containing vessel in which the carbon block e is hung,
forming the cathode and connected with the negative conductor
c, f are the articles to be treated connected to the positive rod d
of the frame g. The rising and sinking of the frame is done by
the spring j, or a similar contrivance fastened to the pulley and
whose motion can be regulated by a clockwork or other mechan-
Fig. 88 shows a process intended for the simultaneous use of
two vessels and in which the objects are alternately dipped into
one vessel and raised out of the other.
a are the holders, g the frames, and i the regulating arrange-
ment, f the objects to be treated fastened to the frames. As one
frame is raised out of the liquid the other one sinks into the liquid.
Fig, 8g shows a further form of the apparatus in which the
change of level of the liquid is attained by the rising and lowering
ELECTROLYTIC ETCHING 137
of a displacement block /. The movement of this block is either
regulated by clockwork or by other means and produces a corre-
sponding rise and fall of the liquid so that the objects dip more or
less into the solution.
Fig. 90 shows a tapered umbrella rib or bicycle spoke with an
enlargement allowed to remain at the end for the forming of a
head or other purpose.
Fig. 91 shows the original form of this rib or spoke with a nick
at the point where the tapered end and the head come together.
Fig. 92 shows a tube, the inner and outer surfaces of which are
tapered by this process.
Fig. 93 shows a tube which is tapered only on the inside.
Fig. 94 finally shows a rod tapered in sections obtained by al-
lowing the fluid to remain stationar}^ at the level where the off-
sets are to be made, or by correspondingly arresting the motion
of the solution at these points.
XV. ELECTROLYTIC ENGRAVINa
INTRODUCTION. -
We have already said that this process is one in which the work
of the engraver is replaced by the use of the electric current. It
has been principally developed by Joseph Rieders^. So far, it has
principally been applied to engraving on metals, and of these
principally on iron and steel.
We will go somewhat into the subject of metal-engraving in
order that the information to be given may be better understood.
There are to be distinguished three kinds of metallic engraving.
The oldest application of this work was concerned with ornament-
ing useful objects in order to increase their commercial value.
This original creative application of the engraving art was char-
acteristic of the early times. The second division of the engrav-
ers work was concerned with the finishing of the reliefs which
had been made by casting; we call this work chasing and the
artist ^a chaser or engraver. The third group finally is concerned
with the manufacture of plates for printing which we call copper
or steel engravings. While it would not appear that the electro-
lytic engraving could revolutionize the field of engraving, as
above described, yet it may become a valuable aid in that part of
the engraving which is concerned with printing, at least by the
use of which objects may be made or embellished by the use of
pressure. Electrolytic engraving is for this reason of importance
for this part of the engraving because it replaces expensive hand
labor by which dies and moulds must be worked from the crude
piece of steel.
For a long time the engraving art has hoped to find in electro-
lytic engraving a rational means of replacing the artistic work
of the engraver by that of the ordinary workman. The work of
Jacobi in the field of copper galvanoplastics raised the general
^Klectrochemische Zeitschrift. i, 1900; Dr. G. lyangbein, Zeitschr. f. Klektrochemie,
4. 139; 6, 328; German Patent 124,529, Feb. 20, 1900; Supplementary to German
Patent 95,081, Feb. 7, 1897.
ELECTROLYTIC ENGRAVING
139
hope that the further pursuit of this Hne would lead to favorable
developments for the engraver. But up to the present it has not
become practicable to produce electrol)rtically deposits of steel
of such physical qualities as ordinary steel ; quite aside from the
fact that the production of heavy iron precipitates, such as are re-
quired in coinage dies takes an enormous length of time. But if
galvanoplastics is to find use in the coinage industry it can only
be in the form of steel galvanoplastics. But the galvanic steel
precipitate lacks toughness in spite of the fact that its hardness is
nearly equal to that of steel ; this is partly due to the absence of
carbon in the iron precipitated, which is the characteristic ingre-
dient of steel.
ENGRAVING WITH PARTIAL COVERING.
If there is no possibility that electrolytic precipitation can come
to the aid of the coming art, yet in electrolytic engraving there is
a possibility of producing stamping dies electrolytically. The
above described etching methods were only in a few rare cases
Fig. 95. Fig. 96.
applicable to the coining industry. If for instance. Fig. 95 rep-
resents a section of an iron plate with the surfaces ab and cd cov-
ered, then the surface be can be etched. If vve afterwards cover
the surface bef and chg we can obtain a second etching within the
limits fg; or altogether we obtain the form befghc. This process
is for example practically used in the manufacture of etched
cliches. In Fig. 96 if it is desired to etch out the form as figured
it would be necessary to coat over very restricted areas in order
to obtain approximately the shape desired. The rounded parts
140 MANUFACTURE OF METALLIC OBJECTS
in particular could not be thus etched out and would have to be
engraved by hand ; the workman on which must actually be an
artist in order to finish the design.
ELECTEO-ENORAVING PBOCEKES.
We will now pass to the electro-engraving processes themselves
of such nature that the use of coverings are completely dispeiisvd
with. The process is based upon the fundamental principle that
for the attainment of the end sought it is completely immaterial
whether the places not to be etched are covered over or whether
the places to be etched only come in contact with the etching
bath. The inventor allows the insulation to be done by a layer of
air and attains this end by producing, by means of a porous mate
rial, a fluid surface which by successive forward movements will
come more and more into contact .with the metal until a reversed
relief is entirely in contact with the metal surface. This will be
clear from an inspection of Fig. 97. The vessel is filled with am-
monium chloride solution which may be regarded as the electro-
lyte. The plaster block is intended to take the engraving to the
steel anode above. The cathode described by the inventor as a
wire spiral is placed underneath the gypsum block. As soon as-
the plaster block is saturated with the electrolyte its upper surface
becomes in reality the upper surface of the electrolyte in relief,
acting as the attacking agent against the steel anode ; the surface
of the plaster being solid prevents the pressure of the steel block
from altering the surface of the electrolyte so that the steel comes
only in contact with the electrolyte at the high places of the plas-
ter relief. The current being then turned on, the chlorine liber-
ELECTROLYTIC ENGRAVING I4I
ated at the anode dissolves iron which diffuses as ferric chloride,
FeClg, into the pores of the plaster. The weight of the steel
anode presses down on the points in relief upon the plaster block
as soon as any appreciable thickness of the steel is dissolved and
the continuance of this pressure brings the anode and plaster
block into better and better contact until the whole of the plaster
block is in contact with the steel anode.
RIEDEB'S EmST INVESTIGATIONS.
•
In his first attempts with this process Rieder used a steel plate
3 mm. thick and his electrolyte a 10 per cent, solution of ammo-
nium chloride. The battery had a tension of 2 volts. The weak
point of this arrangement was that the operation of the etching
process could not be followed, since by taking up and again re-
placing the steel block points of contact were changed.
After this the course of the process was guessed at. After
about one hour's electrolysis it was found that a black mud ap-
peared at the steel anode, after the removal of which the details
of the relief were to be recognized. It was, therefore, necessary
to devise an arrangement which would allow the mould and the
steel anode to be separated during the process in order to be able
to clean the anode. A quite simple model apparatus was devised
by which much better results were obtained, from which Rieder
adduced the following fundamental laws of procedure :
Fundamental Laws,
1. The carbon contained in the steel and possibly also other ad-
mixtures insoluble in the electrolyte, must be mechanically re-
moved from the anode plate from time to time since they lie as a
powder between the plate and the model making exact work im-
possible. The intervals at which this must be done is primarily
dependent on the amount of carbon in the steel to be etched.
2. The ammonium chloride at the surface of the plaster block
is quickly used up, and since the diffusion through the pores of
the plaster is much slower than in a free fluid the amount of am-
monium chloride available at the surface is far below that re-
quired by the process. This condition requires the occasional re-
moval of the steel block at intervals dependent upon the relative
size of the etching surface and the current strength used. The
142 MANUFACTURE OF METALLIC OBJECTS
current density in order to work as fast as possible is used as high
as conditions will permit and taking this into consideration it was
found that 20 seconds is the maximum interval of working which
must not be exceeded.
Behavior of the Steel Anodes.
The black mass mentioned above which lies between the steel
plate and the plaster block is not only carbon but largely ferrous
oxide. It sefems that as soon as the chlorine at the surface of the
plaster model is used up tlfere is no longer electrolysis of ammo-
nium chloride, but decomposition of water takes place. The
oxygen thus liberated at the anode forms with the iron an in-
soluble ferrous oxide which deposits upon the anode and stops the
etching. The evolution of gases at the anode also expels electro-
lyte from the etching surface and produces irregularities in the
etching.
The Plaster Used.
Rieder met many difficulties in finding the most suitable com-
position for the plaster blocks. At first he used alabaster plaster,
which, however, had the great inconvenience that as soon as it
was saturated with electrolyte it became extremely easily injured
as soon as the anode was let down upon it. It was hardly possible
;to find a substitute for plaster since the other self -hardening
materials do not have the porosity which makes gypsum so suit-
able for this process. Rieder made investigations, by altering the
relative weights of water and plaster used to find such a composi-
tion which would be durable and yet porous. Another device
appeared to be that of making several similar models which
could replace each other as soon as one was injured; but this met
with the difficulty of placing the models always in exactly the
same position. He afterwards succeeded by using a special meth-
od of casting the plaster, which in combination with satisfactory
tests upon mixtures used gave quite good results.
Mechanical Devices.
Fig. 98 shows some of the mechanical apparatus of the process,
^ is a glass vessel with the lid d having an offset on which is
placed the plaster model B surrounded by a rubber mantel C. It
ELECTROLYTIC ENGRAVING I43
may be interesting to remark here the manner in which it is pos-
sible to replace the plaster blocks in the later machines. Sev-
eral rubber mantels c are made in which the similar models are
cast so that they are fastened in the cover in exactly the same posi-
Fiff. 98-
tion, to which end a mark is made upon the cover.
The anode to be etched is at A. This was an exactly cylindri-
cally turned steel plate prevented from turning sideways by a
pointer not shown in the figure. The anode fits exactly into the
opening of the cover d.
The apparatus had to be converted into an automatically work-
ing machine, which was done by the firm of Dr. G. Langbein &
Company, of Leipsic, as shown in Fig. 99. The description is
briefly as follows : The plaster mould is fastened by two conical
wedges into the cast iron frame upon a vertically moving table,
the latter worked by an eccentric. Above this table is the clamp-
ing plate to hold the steel anode to be etched. The clamping plate
is likewise adjustable and can be fastened exactly parallel to the
mould by a suitable adjustment. A carriage having a rotating
brush and movable by an eccentric cleans off the steel plate, the
brushes being washed oi¥ by water, while, besides a sponge roller
is carried over the mould for the purpose of wetting it with elec-
trolyte.
Action of the Machine.
The mould upon the movable table is applied to the plate to be
etched without shock and as elastically as possible ; after being in
contact 15 seconds and during which electrolysis takes place the
mould is lowered from contact with the anode and the cleaning
processes by the brushing and sponging rollers take place. As
soon as the cleaning appliances have been withdrawn the mould
is again brought against the steel plate and the operation repeated.
144 MANUFACTURE OF METALLIC OBJECTS
For each machine there is a mould casting arrangement, in
which the frames of the machine are cast into place.
The Dynamo.
The dynamo used gives a tension of 12 vohs to 15 volts and
the current used for a plate 200 x 300 mm. is about 50 amperes, if
P'S- 99-
the whole surface of the plaster model comes into contact .with the
steel plate. An electrolytic engraving plant of this kind was ex-
hibited at the Paris Exposition in 1900.
Dtiralioii of the Etching.
According to the depth of the etching the operation may take
ElyECTROLYTlC ENGRAVING I4S
more or less time, about 4 or 5 hours being required for a depth
of I mm., varying somewhat with the fineness of the model. The
cleaning of the same can, if desired, be accomplished with the as-
sistance of compressed air. If the duration of etching is 12 sec-
onds, some 600 to 800 etching periods must be used in order to
-etch to the depth of i mm.
Patent Claims.
German Patent, 95,081, February 7, 1897.
1. The process of forming reliefs and other shapes electrolyti-
>cally by using a negative in the shape of a porous mass, such as
plaster, clay, or the like, cast or cut, using the article to be formed
as anode pressing lightly upon the forming side of the porous
block saturated with a suitable electrolyte, and a cathode im-
mersed in the electrolyte.
2. The apparatus for the carrying out of the process of Claim
I, consisting of a porous block upon which is a negative of the
design to be produced and whose forming surface rests with a
light pressure against the anode to be formed, and which is sa^.i-
rated with electrolyte; the block being further encased in an
^encasing mantel and the position of the anode being assured by
guides.
German Patent, 124,529, February 20, 1900; an addition to
the previous patent.
1. A device for the carrying out of the process of forming re-
liefs and other designs electrolytically according to patent 95,081,
consisting in placing the negative upon a vertically moving table
.above which is the anode so that when the table is lowered in the
manner provided, a slide carrying a cleaning brush for the anode
-can pass between the negative and the anode, while a moistening
roller supplies the porous block with fresh electrolyte in order to
counteract the alkalinity of the electrolyte upon the surface of
the negative.
2. An apparatus for the carrying out of the purposes of Claim
I, characterized by means for automatically raising the negative
l)y means of a lever as the etching proceeds.
Manufacture of the Machines,
The maimfacture of electro-engraving machines is in the hands
146 MANUFACTURE OF METALLIC OBJECTS
of the Elektrogravure G. m. b. H., in Leipsic, and we take from
the catalogue of this firm the following data concerning the ma-
chines, their listing and price :
Machine.
No.
E.
El
E,
E,
Engraving of
Surface
m.m.
50 X 50
120 X 150
200X300
350 X 450
Necessary for
Etching.
Volts. Amperes.
15 2 — 3
15 15
15 30
15 60
Total Power
used: H. P.
0.40
I.OO
1.35
2.50
Price of the
complete
installation
$ 625.00
1125.00
1725.00
E,.
E,.
I125.00
I150.OO
0.75
i.oH.P.
The air compressor is only used when engravings deeper than
3 mm. are to be made. When engraving not so deep the cleaning
by means of the brush and sponge roller suffices. The price given
above includes the air compressor and the power data includes its
power consumption. If the air compressor is not used the price
of the machine and its power requirement is as follows :
For machines. Ei.
Deduct from price .... |ioo.oo
Deduct from power .... 0.5
In the price for these plants the cost of the dynamo is not in-
cluded, but the license for using the German Patent goes with the
machine, good for the use of the machine during the life of the
patent.
Auxiliary Apparatus,
The necessary conditions for the carrying out of electro-en-
graving is the possession of an original model of wax, plaster,
wood, etc., from which the necessary plaster moulds needed for
the electro-engraving can be reproduced in numerous duplicates.
For these purposes a complete plant must contain the following
auxiliary apparatus.
Two casting apparatus for 20 frames ; one drying oven for dry-
ing the plaster moulds rapidly, arranged for burning spirits, petro-
leum, or gas.
Plant for Electro-Engravure.
Fig. 100 shows the ground plan for the erection of an electro-
engraving plant of a capacity indicated in the table by the figure
Eg. Such a plant has been erected in Moscow by the Faberge
Silverware House.
ELECTROLYTIC ENGRAVING I47
Cost of Making Dies.
The cost of making finished electro-engraved dies depends upon
the depth of etching and the dimensions of the mould. It also de-
pends on whether the engraving is to be afterwards engraved or
chased, or whether it is to be ready for use when it comes from
the machine.
Prowls.
The approximate estimate of the profits of an electro-engraving
plant have been made as follows by the author :
The machine of the size, Ej, will produce about 10 dies at once
having a maximum etched depth of 2 millimeters. These dies
148 MANUFACTURE OF METALLIC OBJECTS
are quite fine work, which, if made by hand, would be worth»
$37.50 apiece.
FIXED PLANT.
I Electro-engraving machine, E]* having a maximum
engraving surface of 200X300 mm., including
air compressor { 1750.00
I. dynamo machine, 30 amperes, at 15 volts, including
shunt regulator, ammeter, voltmeter, and switch* 125.00
Shafting, pulleys and small appliances 125.00
Total investment in plant $ 2000.00
COST OF PRODUCING TEN DIES.
Power, 10 days of 10 hours each ; equals 150 H. P.
hours at i>^c. per H. P.-hour $ 2.25
I engraver for touching up the dies at {1.50 per day • • 15.00
I moulder and i engineer for 10 days 21.25
150 kilos of steel at |2o per 100 kilos 30.00
10 fo sinking fund on the capital invested for 10 days. 6.67
5% interest on capital for 10 days 3.33
Government tax 50% on the wages 13* 13
•
Cost of producing 10 stamps $ 94.12
PROFITS.
Value of produce (one die per day 200X300 mm.)
per year of 300 working days I11250.00
Cost of 300 dies according to the above assumption . . 2823.65
Leaving as yearly profit $ 8426.35
Corresponding to a dividend of 420 per cent.
It may be said that these figures make no claim to be true since-
very much depends on the cost of labor for running the machine.
The profits must be smaller when work is produced which must
compete with cheap hand labor. With increasing fineness of "the
work, however, the cost of manufacturing them by hand in-
creases rapidly and the profits of the electro-engraving process-
will increase when producing such fine work.
APPENDIX,
TABLE I.
STRENGTH TESTS OF GAI,VANOPLASTlCAI,I,Y FORMED COPPER PRINTING
PIRATES.
d .
•
•
mpositio
the bath
S
.2
1
%
Cd
•
So
u
ii
d
%
'e
S
cd
%
V
^
■*^
a
f
•
B
(0
c
V
1
a
a
'i
9
t
r
>
u
5
Dimen-
tions of
the strip
before
testing.
X
a
H
1)
a
o
Si
^'
a
a
u
%
S
I.
II.
Elastic
Xyixnit.
Kg. per sp. centi.i
Elongation
to the
I.
II.
Elastic
I^imit.
a*i
e
^•2
cd
it
a <e
s
After
breaking.
cd
cd
Cd
a
bo
•c
O
'o il bo
dj > o •
a S-.S ^
boiS
N
4;iM >C
■T3J3 .^"^
£a «
z
Drop-
ping.
50
100
mm.
mm.
to
•a
&
2
3
4
5
6
7
8
9
10
II
13
13
13
14
15
16
17
18
19
20
21
30
17
14
10
30
15
10
22 20
23
23
24
2
s
%
2
o
o
0.61
I.OO
1.25
1.67
2.23
0.85
I.SO
0.85
1.50
0.85
1.50
I.OO
I.OO
I. so
2.50
4.00
I.OO
1.50
3-23
I.OO
1.50
1.30
I.OO
;
1
n t
0.71
2838
739-5
950.5
0.062
0.082
0.74
3270
845
1080.5 ;o.07o 0.090" 1
0.74
3378
776.5
1047
938.5
0.067 1 0.093
0.051 0.080
0.80
3605.5
625.5
0.73
0796
3724.5
2855
754
692.5
?flnr
0.056
0.030
0.073
0.070
0.75
36195
566.5
733
0.U41
0.055*
0.84
2517
7U
833
0056
0.064
0.86
3238
552
843
0.0426
0.0726
0.84
2500
714
952
0.053
0,0736
0.846
3532
710
m.
0.058
0.0856
0.866
2715
520
0.043
0.076
0.801
2440.5
482
748.5
855.5
0044
o.o§4
0.080
1.237
2941
509
0.046
0.847*
2949.5
472
678.5
0.0366
0.050
0.068
'•^
2404.5
489
716.5
0.044
1.12*
2738
444
664. s
0037
0.05B6
1 012
2795-5
517.5
727.5
0.0436
0.0746
042
3013
513
820
0035
0.063
0.69
2674
464
753
0.0366
0.0626
0.598
2803.5
401.5
772
0.0276
0.0616
0.606
2760.5
564
596
0.023
0.0416
10
10
1-93
2802.5
583
849.5
0.052
0.077
0,805
0.796
2540
571.5
961.5
0.042
o.o8c6
2534
503
981
0.041
0.085
1-55
4230
733
921
0.049
0.054
27.06
22.56
17.6
16.6
16
30.9.
27.5*
1496
20.2
6.1
10.3
26.4
5.7
26.4
19.4*^
330;
28.56
19.4
17.26
19.76
12.5
1.8
I
0.607
0677
0.643
0.619
0.643
0596
o 622
0.836
05^3*
0.889
0.752
0.642*
0.807*
05416
0.6676
0.6636
0.5206
0.5606
0.685
0.4866
0.762*
0.720*
0.827
0.971*
0.987
1.5 0442
6.6
6.2
6
6.2
5-7|
64'
6.61
6.7
6.7
5.9
7
6.8
6.8
7.1
6.7
7.1
6.9
6.T
6.6
6.6
6.5
6.6
6.7
7-9
8.2
7-3
8
7
8.1
8.1
8.T
8.4
7.9
8.4
8
7-9
7.7
7.8
8.2
8.1
7.8
7.8
cd
cd
I§
2 a c j3 a
- - VM
O N «
«< V a«
•o r^ a
cd
.5= .
*? 2
a
Cd
M
C Cd
V bo
bo
1 1,000 Kg per square centimeter = 14,300 pounds per square inch.
TABLE II.
CONDUCTIVITY OF EI,ECTROI.YTES WHICH ARE USED IN THE MANUFACTURE
OF METAI.I.IC OBJECTS.^ ^
The table refers to temperature of solutions of i8® C.
P^= percentage by weight of anhydrous salt in the solution.
7^ = number of gram-equivalents of salt in a cubic centimeter of solution.
5" = specific gravity of the solution at i8® C, or at 15® C, compared with
water at 4® C.
Xy^-=- conductivity of the solution in reciprocal ohms per cubic centimeter
(i)"
i8«C.
The temperature coeflScient gives in fractional parts of x-^^ the alteratio**
of X for one degree, for which is taken the mean alteration betwee^
18® and 26®.
Interpolated values are in parenthesis.
Elektrolyt
p
*
1000 1} im:ilv)
StU
IC^li
2.5
0.321
1.0246
109
0.0213
5.
0.658
1. 0531
189
0.0216
CuSo^
10.
1.387
1. 1073
320
0.0218
15.
2.194
1. 1575
421
0.0231
17.5
2.631
1.2003
458
0.0236
5
0.651
1.0509
191
0.0225
ID
I.37I
1. 1069
321
0.0223
ZhSOa
15
2.169
1. 1675
4i§
0.0228
(20)
3.053
1.2323
468
0.0241
25
4.040
1 .3045
480
0.0258
(30)
5.124
1.3788
444
0.0273
___
• 0.5
I 0344
154
0.0218
I
1.0692
258
0.0218
FeSO,
2
1. 1375
390
0.0223
3
I. 2018
461
0.023 [
3.56
1.2359
470
0.0243
— -
0.5
1.0379
153
0.0231
NiSOs.
I
1.0759
254
0.0227
2
1. 1503
385
0.024 r
3
I. 2219
452
0.0250
5
0.307
1.0422
256
0.0218
10
0.641
1.0893
476
0.0217
(•5)
1.006
1. 1404
683
0.0215
20
1.407
I. 1958
872
0.0212
(25)
1.847
1.2555
1058
0.0210
AgNO,,
(30
(35)
2.332
2.872
1.3213
1.3945
1239
1406
0.0209
0.0207
40
3.477
1.4773
1565
0.0205
(45)
4.158
1.5705
1716
0.0204
(50
(55)
4.926
1.6745
1856
0.0205
5.791
1.7895
1984
0.02(56
60
6.764
1.9158
2101
6.0209
1 The figures are mostly taken from the work of Kohlrausch and Holborn, " Das
Ceitvermogen der Elektrolyte," 1898.
Blektrolyt
p
1000 i| (fn:i/z;)
Sih
vAxyL
xx% ^ dt 'n
(Kohlrausch
8, 1879)
5
10
15
0.735
1.536
2.411
1.0450
I.09I5
I. 1426
409
687
886
0.0236
0.0249
0.0256
(Klein 1886)
.0.5
I.
1.0302
1.0602
298
508
0.0241
0.0242
2.
I. "79
800
0.0250
5
0.873
I. 05 10
263
0.0226
MgSO,
10
15
(20)
25
1.836
2.89T
4.054
5.342
1. 1052
1. 1602
1.2200
1. 2861
414
480
476
415
0.0241
0.0252
0.0269
0.0288
J^CN
3.25
6.5
5
0.778
1.0292
552
0.0215
(N//,),SO,
10
1.601
1.0581
lOIO
0.0203
Kohlrauscn
20
3-337
1.1160
1779
0.0193
8, 1879)
30
5.322
1. 1730
2292
0.0 1 91
31
5.528
I. 1787
2321
0.0191
5
0.948
1.0142
918
0.0198
10
1.923
1.0289
1776
0.0186
NHiCl
15
2.924
1.0430
2596
0.017 1
20
3.952
1.0571
3365
0.0161
25
5.003
1.0710
4025
0.0154
0.506
1.029
^=15
I.OI54
1.0316
527
1026
0.0207
0.0193
3
M
O .§
to
5
10
15
20
25
30
35
40
(45)
50
(55)
60
65
70
75
80
85
90
95
1.053
2.176
3.376
4.655
6.019
7.468
9.01 1
10.649
12.396
14.258
16.248
18.375
20.177
23.047
25592
28.25
30.90
33.34
35.58
1. 033 1
1.0673
1.1036
1.1414
1. 1807
1.2207
1.2625
1.3056
1.3508
1.3984
1.4487
1.5019
1.5577
1. 6 146
1.6734
1.7320
1.7827
1.8167
1.8368
(Bock 1887)
Aquiv.
0.776
1.92
2.88
3.612
0.377
0.936
1.409
1.771
/=i8
1.0029
1.0073
1. 0109
I.OI3I
2085
3915
5432
6527
717I
7388
7243
6800
6146
5405
4576
3726
2905
2157
1522
IICJ5
980
1075
1025
0.022
O.II
0.21
0.31
O.OI2I
0.0128
0.0136
0.0145
0.0154
0.0162
0.0170
0.0178
0.0186
0.0193
0.0201
0.0213
0.0230
0.0256
0.0291
0.0349
0.0365
0.0320
0.0279
0.0231
0.0143
O.OIII
0.0075
o
00
152
MANUB'ACTURK OI? METALLIC OBJECTS
TABLE III.
SPECIFIC RESISTANCE OF A CUBE OF ELECTROLYTE ONE DECIMETER ON
A SIDE. (ohms).
loooiy (m).
HiSO^.
CuSO^.
1000 T) (m).
H^O^.
CuSOi.
O.OOI
277-0
lOOO.O
O.I
4.444
22.2
0.002
143.0
527.0
0.2
2.337
12.8
0.005
58.8
244.0
0.3
1.587
9.3.S
0.5
0.976
6.49
O.OI
32.2
139.0
I.O
0.504
3.875
0.02
17.5
76.9
2
0.273
2.497
003
12.2
58.8
30
0.199
2083
0.05
7.87
38.5
5.0
0.148
• • • •
lO.O
0.143
• • • •
TABLE IV.
WEIGHTS OF COPPER PRECIPITATES OBTAINED FROM ACID SOLUTIONS.
Current density
used.
Amp. per sq. dm.
Weight of a s
I hour.
(qua re decimeter <
2 hours.
of the precipitate
5 hours.
in grams after
10 hours.
0.5
0.75
I.OO
0.59
0.89
1. 18
I.r8
1.78 ,
2.36
2.96
4.44
5.92
5.92
8.87
TI.84
1-25
1.50
1.75
2.00
1.48
1.78
2.07
2.37
2.96
3.56
4.14
4.74
7.40
8.88
10.37
11.85
14.80
17.76
20.74
23.70
2.25
2.50
2.75
3.00
2.67
2.96
3.26
3-55
5.34
5.92
6.52
7.10
13.33
14.80
16.28
17.75
26.65
29.60
32.55
35.50
3.5
4.0
4-^5
4.74
8.30
9.48
20.75
23.70
4^.50
47.40
4.5
5.0
532
5.90
10.64
11.80
26.60
29.50
53.20
59.00
5.5
6.0
• 6.50
7.10
13.00
14.20
32.50
35.50
65.00
71.00
6.5
7.0
7.70
8.30
15.40
16.60
38.50
41.50
77.00
83.00
7.5
8.0
8.90 ^
9.45
1 7. So
18.90
44.50
47.25
89.00
9450
8.5
9.0
10.05
10.70
20.10
21.40
50.25
5350
100.50
107.00
9.5
lO.O
11.25
11.80
22.50
23.60
56.25
58.00
112.50
118.00
APPENDIX
153
TABLE V.
THICKNBSS OF COPPER PRECIPITATES.
Current
density
used.
Number of hours required for a thickness of
0.1
mm
0.2
mm
0.3
mm
0.4
mm
0.5
mm
0.6
mm
0:7
mm
0.8
mm
0.9
mm
1.0
mm
Thickness
of the
copijer
precipitate
in 10 hours
in milli-
meters.
0.5
0.75
r.oo
1.25
1.50
1.75
2.00
2.25
2.50
2.75
3.00
3-5
4.0
4.5
5-Q
5.5
6.0
"6y
7.0
7.5
8.0
8.5
9.0
9-5
lo.o
I5.I
10. 1
7.5
30.2
20.2
15.0
12.0
1 0.0
8.6
7-5
6.7
6.0
5-5
50
45.3
30.6
22.5
6.0
5.0
4.3
3 75
18.0
15.0
12.9
11.25
10.05
9.00
825
7.5
6.45
5.64
3.35
3.00
2.75
2.5
2.15
i.8i;
4.3
376
3.3
3.0
2.7
2.5
2.3
2.16
2.0
1.86
1.76
1.66
1.65
1.5
1.35
1.25
1.15
1.08
4.95
4.5
4.05
3.75
3.45
3.24
3.0
2.79
1.0
0.93
0.88
0.83
0.79
0.75
2.64
2.49
1.58
1.50
2.37
2.25
60.4
40.4
w.o
24.0
20.0
17.2
T50
75.5
50.5
37.5
30.0
25.0
21.5
18.7522.5
90.6
61.2
' 45.0
I36.0
i30.o
'25.8
13-4
12.0
ii.o
lO.O
"8:6"
7.52
16.75 20.1
15.0018.0
13.75116.5
12.5 I 15.0
10.75
9.4
6.6
6.0
JJ
5.0
4.6
4.32
8.25
7.5
6.75
6.25
5.75
5.4
4.0
3.72
3.52
3.32
3.16
3.0
5.0
4.6
4.4
4.15
3.9
3.75
12.9
11.28
9-9
8.1
7.5
6.9
6.48
6.0
5.58
5.28
4.98
4.74
4.50
105.7
71.0
52.0
42.0
35.0
30.1
26.25
23.45
2I.OC
19.25
17.5
15.5
13.16
11.55
10.5
9.45
8.75
8.05
7.56
|20.8
80.8
60.0
48.0
40.0
34-4
30.0
26.8
24.0
22.0
20. n
17.2
1504
132
12.0
10.8
lO.O
92
8.62
8.0
7.44
7.04
6.64
6.32
6.0
135-9
90.9
67.5
54.0
45.0
38.7
33-75
30.15
27.00
24.75
22.5
19.35
16.92
14.85
13.5
12.15
11.25
10.35
9.72
9.0
8.32
7.92
7.72
7.06
6.75
7.0
6.51
6.16
5.81
5.53
5.25
I5I.0
lOI.O
750
60.0
50.0
43.' »
37.5
33.5
30.0
27.5
25.0
0.0664
0.0995
0.133
0.166
0.199
0.233
0.267
0.299
0.332
0.366
0.399
21.5
18.75
16.5
15.0
13.5
12.5
II.5
10.75
1 0.0
9.33
8.83
8.33
0.466
0.534
0.598
0.664
0.732
0.798
0.864
0.930
1. 000
1.065
1. 126
1.200
7.9^
7.5
1.260
1.330
The numbers in the above table are only true for homogeneous current
distribution and do not apply to edges or like cases where the current dis-
tribution may have various values.
TABLE VI.
AUXII.IARY TABI,E FOR USE IN THE MANUFACTURE OF COPPER WIRE.
For wires of a
diameter
in millimeters
of
Surface of one
meter length
in square
decimeters.
Current rcq
density
0.5
[uired for one m
in amperes per
1.0
eter length at a
square decimet
1.5
current
erof
2.0
I
2
0.31
0.62
0.15
0.30
0.30
0.60
0.45
0.90 •
0.60
1.20
3
4
0.93
1.24
0.45
0.60
0.90
1.20
1.35
1.80
1.80
2.40
5
6
1.55
1.86
0.75
0.90
1.50
1.80
2.25
2.70
3.00
3.60
7
2.17
1.05
2.10
3.15
4.20
TABLE VII (a).
WEIGHT OF SBAMI,ESS COPPER TUBES PER RUNNING METER IN KII,0-
GRAMS, (made by THE ELMORE PROCESS).
Inside
diam-
Thickness of wall in millimeters
eter in
mm
I mm
|i^ mm 1% mm i^ mm
2 mm
2^ mm
3 mm
354 mm
4 mm
5 mm
3
0.11
0.16
0.19
0.28
0.28
0.89
0.61
0.64
1
^^
4
.14
.18
•23
.28
.34
.46
•59
.74
—
—
5
.17
.22
.28
•33
•40
•53
.84
1.02
—
6
.20
.26
.32
.38
.45
.60
^76
.94
.13
1.66
7
.23
.29
.36
.43
.51
.67
.85
1.04
.24
.70
8
.25
•33
.40
.48
•56
•74
.93
.14
.36
•84
9
.28
.36
•44
•53
.62
.81
1.02
.24
.47
•98
lO
•31
.40
•49
•58
.68
.88
.10
.34
•58
2.12
II
.34
•43
•53
.63
.73
.95
.19
.43
.70
.26
12
.37
.47
.57
.68
•79
1.02
•27
.53
.81
.40
13
.50
•30
.61
•73
.85
.07
.36
.63
.92
•54
14
.42
.54
.66
•78
.90
.17
.44
•73
2.04
.69
15
.45
•57
.70
.83
.96
.24
•53
.83
.15
•83
i6
.48
.61
.74
•89
1.02
.31
.61
.93
.26
•97
17
.51
.64
.78
•93
.07
•38
.70
2.08
•37
8.11
i8
.54
.68
.83
.98
•13
.45
•78
•13
.49
.25
19
.57
•72
.87
1.08
•19
.52
.87
•23
.60
•39
20
•59
.75
•91
.08
.24
.59
.95
•33
•71
.53
21
.62
.79
•95
.13
.30
.66
2.04
.42
•83
.68
22
.65
.82
1.00
•17
.36
.73
.12
.52
.94
.82
23
.68
.86
.04
.22
.41
.80
.20
.62
8.05
.96
24
.71
.89
.08
.27
.47
.87
.29
.72
.17
4.10
25
.73
•93
.12
•32
•53
•94
.37
.82
.28
.24
26
.76
,96
.17
.37
.58
2.01
.46
•92
.36
.38
27
.79
1.00
.21
•42
.64
.08
.54
8.02
.50
•52
28
.82
•03
.25
•47
.70
.16
.63
.12
.62
.66
29
.85
.07
.29
.52
.75
•23
.71
.22
.73
.81
30
.88
.10
•34
.57
.81
.30
.80
•31
.84
•95
31
.90
.14
.38
.62
•87
.37
.88
•41
.96
5.09
32
•93
• 17
.42
•67
•93
.44
.97
.51
4.07
.23
33
.96
.21
.46
.72
.98
.51
3.05
.61
.18
.37
34
•99
•25
51
•77
2.04
•58
.14
.71
.30
.51
35
1.02
.28
.55
.82
.09
.65
.22
.81
.41
.66
36
.05
.32
•59
.87
• 15
•72
.31
.91
.52
.80
37
.07
.35
•63
•92
.20
•79
.39
4.01
.64
•94
38
.10
.39
.67
.97
.26
.86
.48
.11
.75
6.08
39
.13
.42
•72
2.02
.32
•93
.56
.21
.86
.22
40
.16
.46
• 76
.07
.37
8.00
•65
•30
•98
.36
41
.19
.49
.80
.11
.43
,07
.73
.40
6.09
.50
42
.22
.53
.84
.16
.49
.14
.82
.50
.20
.64
43
.24
.56
•89
.21
.54
.22
.90
.60
.32
.79
44
.27
.60
.93
.26
.60
•29
.99
.70
.43
•93
45
.30
.63
•97
.31
.66
.36
4.07
.80
.54
7.07
46
•33
.67
2.01
.36
.71
•43
.16
.90
.65
.21
47
.36
.70
.06
•41
.77
.50
.24
6.00
.77
•35
48
.38
.74
.10
.46
.83
.56
.33
.10
.88
•49
Inside
diam-
Thickness of wall in millimeters
•
eter in
mm
I mm
i}i mm
1% mm
iK mm
2 mm
2% mm
3 mm
3% nim
4 mm
5 mm
49
.41
.78
.14
.51
.88
.64
.41
.19
•99
•63
50
.44
.81
.i8
•56
.94
•71
•50
.29
6.11
• 77
51
.47
.85
.23
.61
8.00
•78
.58
.39
.22
•92
52
.50
.88
•27
.66
•05
.85
.66
.49
.33
8.06
53
.53
.92
.31
•71
.11
.92
•75
.59
•45
.20
54
.55
.95
.35
•76
.17
•99
.83
.69
.56
•34
55
.58
•99
.40
.81
.22
4.06
^'l^
.79
•67
.48
56
.61
2.02
.44
.86
.28
.13
6.00
.89
.79
.62
57
.64
.06
.48
.91
.34
.21
.09
•99
.90
.76
58
.67
.09
•52
.96
.39
.28
• 17
6.09
7.01
.91
59
.70
.13
.56
8.01
.45
•35
.26
.18
.12
9.06
60
.72
.16
.61
.05
•51
.42
•34
.28
.24
.19
61
.75
.20
.65
.10
•56
.49
•43
.38
^ .35
.33
62
. .78
.23
.69
•15
.62
.56
.52
.48
.46
•47
63
.81
.27
.73
.20
.68
.63
.60
•58
•58
.61
64
.84
.31
.78
•25
.72
.70
.68
.68
.69
.75
65
.87
.34
.82
•30
•79
•77
•77
.78
.80
.90
66
.89
.38
.86
•35
•85
.84
.85
.88
.92
10.04
67
.92
.41
.90
.40
.90
•91
-•91
.98
8.08
.18
68
.95
.45
.95
•45
.96
.98
6.02
7.08
• 14
.32
69
.98
.48
•99
.50
4.01
5.06
.11
.17
.26
.46
70
2.01
•52
SOS
.55
•07
.12
•19
.27
•37
.60
71
.04
.55
.07
.60
• 13
• 19
.28
•37
.48
.74
72
.06
.59
.12
.65
.18
•27
•36
.47
•59
.89
73
.09
.62
.16
.70
.24
.34
•45
•57
.71
11.08
74
.12
.66
.20
.75
•30
.41
•53
•67
.82
.17
75
.15
.69
.24
.80
•35
.48
.62
.77
.93
.31
76
.18
.73
.29
.85
.41
.55
•72
.87
9.06
.45
77
.21
.76
•33
.90
•47
.62
.78
.97
.16
•59
78
.23
.80
.37
•95
•52
.69
•87
8.06
.27
•73
79
.26
.84
.41
4.00
.58
.76
.95.
.16
.39
.87
80
.29
.87
.46
.04
.64
.83
7.04
.26
.50
12.02
81
.32
•91
.50
.09
.69
.90
.12
.36
.61
.16
82
•35
•94
.54
.14
.74
.97
.21
•46
•73
.30
83
.38
.98
.58
•19
.81
6.04
.29
•56
.84
•44
84
.40
8.01
.63
•24
.86
.11
•38
.66
.95
.58
85
.43
•05
•67
•29
•92
.18
.46
• 76
10.07
•73
86
.46
.08
•71
.34
•98
.26
.55
.86
.18
.86
87
•49
.12
.75
.39
5.08
•33
.63
.96
.29
18.01
88
•52
• 15
.80
.44
.09
.40-
.72
9.06
.40
• 15
89
.55
• 19
•84
.49
•15
•47
.80
• 15
•52
.29
90
.57
.22
.88
.54
.20
•54
.89
•25
.63
•43
91
.60
.26
•92
•59
.26
.61
•97
.35
•74
•57
92
•63
.29
.96
.64
•31
.68
8.06
.45
.86
.71
93
.65
•33
4.01
.69
•37
.75
.14
•55
. -97
•85
94
.68
.37
•05
•74
•43
.82
.23
.65
11.08
14.00
95
.71
.40
.09
.79
•48
.89
.31
.75
.20
• 14
96
.74
.44
.13
.84
.54
.96
.40
•85
.31
.28
97
.77
.47
.18
•89
.60
7.08
.48
.94
•42
•42
156
MANUFACTURE OF METALLIC OBJECTS
Inside
diam-
eter in
mm
Thickness of wall in millimeters,
I mm
i}( mm
i^ mm i^ mm
2 mm
2^ mm' 3 mm 3H mmj 4 mm
5 mm
98
99
100
TOI
102
103
104
105
106
107
108
109
1 10
III
112
113
114
"5
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
.80
.51
.22
•94
.65
.10
•57
.83
.54
.26
•99
.71
.17
•65
.86
.58
.30
6.08
•77
.24
.74
.88
.61
.35
.08
.82
.32
.82
.91
i^
.39
.13
.88
.39
.91
.94
.68
.43
.18
•94
.46
•99
.97
.72
.47
•^3
•99
•53
9.08
8.00
.75
.52
.28
6.06
.60
.16
•03
.79
.56
.33
.11
.67
.25
.05
.82
.60
.38
.16
.74
•33
.08'
.86
.64
.43
.22
.81
.42
.11
.90
.69
.48
.28
.88
•50
.14
.93
.73
.53
.33
.95
•59
.17
.97
.77
.58
•39
8.02
.67
.19
4.00
.81
.63
.45
.09
.76
.22
.04
.86
.68
•50
.16
.84
.25
.07
.90
•73
.56
•23
•93
.28
.11
•94
.78
.61
•30
10.01
.31
.14
.98
•S3
.67
.38
.10
.34
.18
5.08
.88
•73
.45
.18
.36
.21
.07
•93
.78
.52
.27
.39
.25
.11
.08
.84
•59
•35
.42
.28
.15
6.08
.90
.66
.44
.45
.32
.19
.07
•95
•73
•52
.48
.35
.24
.12
7.01
.80
.61
.51
•39
.28
.17
.07
.87
.69
.53
.43
•32
.22
.12
.94
.78
.56
.46
•36
.27
.17
9.01
.86
.59
.50
.41
•32
.24
.08
•95
.62
.53
•45
•37
.29
.15
11 08
.65
.57
.49
.42
•34
.22
.12
.68
.60
•53
.47
.41
.29
.20
.70
.64
•58
.52
.46
.36
.28
10.04
.14
.24
•34
.44
.54
.64
.74
.84
.93
11.08
.13
.23
.33
•43
•53
.63
•73
.83
•93
12.02
.12
.22
.32
.42
.52
.62
.72
.82
.92
18.01
.11
.21
.54
.65
.76
.87
.99
12.10
.21
.33
.44
•55
.67
.78
.89
18.00
.12
•23
.34
.46
.57
.68
.80
14.02
14
25
36
48
59
70
82
93
15.04
.15
15
.56
70
.84
99
18
,27
.41
55
69
83
98
16.12
.26
40
54
68
82
97
1711
25
.39
.53
.67
81
95
18.09
23
37
51
65
79
93
19.08
APPENDIX
157
TABLE VII (b).
IVEIGHT OF SBAMI«ESS COPPER TUBES PER RUNNING METER IN KILO-
GRAMS, (made by THE EI«MORE PROCESS).
Inside
diam-
Thickness of wall in millimeters.
eter in
mm
i^ mm
2 mm
2% mm
3 mm
sH mm
4 mm
5 mm
6 mm
7 mm
H mm
131
6.66
7.62
9.48
11.87
18.81
1627
19.28
2826
27.82
81.46
132
.62
.57
.50
.45
.41
•38
•37
•41
.51
.66
133
.66
.63
.58
.54
.53
•53
•55
.62
•74
.90
134
.71
.69
■65
.62
.64
.66
•71
•76
•94
82.12
-135
.76
.74
.71
.71
.73
.76
.82
.92
28.15
•35
136
.81
.80
.78
.79
.81
•83
.94
24 08
.31
•57
137
.86
.86
.86
.88
.90
•93
20.06
.21
.46
.«o
138
.91
•91
•9^
.97
14.00
16.04
.18
•36
.70
88.06
^39
.96
.97
10.00
12.05
.11
.17
.33
.60
.94
.25
140
7.01
8.08
.07
.13
.20
•29
•59
•77
29.11
•47
141
.06
.08
.14
.21
.29
.40
.70
•93
•^2
.69
142
.11
.14
.21
.29
•39
.52
.81
26.09
•48
.93
^43
.16
.20
.28
.38
•49
.63
;93
.26
.68
84.15
144
.21
.25
.35
.47
.60
.74
21.06
.45
«^^
•38
^45
.25
.31
,42
.56
.70
•85
.21
.61
80.09
.61
J 46
•3^
.36
.49
.64
.80
.96
•35
.78
.28
.8.^
147
.35
.42
.57
.73
.90
17.07
•49
•95
•48
85.06
148
.41
.48
.64
.82
16.00
•19
•64
26.18
.68
.29
«49
•45
.53
.70
.90
09
•30
•77
•29
• .88
•51
150
.51
.60
.77
.98
.19
•41
•91
•46
81.08
.73
J^ST
.55
.65
.85
18.06
.29
•53
22.05
•63
.28
.96
«52
.61
.70
.92
.14
•38
.64
•19
.80
•47
86.18
153
.65
.76
.99
.22
.48
.75
•33
.97
.66
.41
154
.70
.82
11.06
.31
•58
•87
•47
27.14
.86
•64
Jf55
.75
.87
.13
•39
.68
.98
.61
.31
82.06
.86
156
.80
.93
.20
.48
.78
18.10
• 76
.48
.26
8709
157
.85
.99
.27
.57
.89
.22
•91
.66
.46
•32
«58
.90
9.05
.34
.65
.98
.33
28.05
.82
.66
.55
159
•95
.10
.41
.73
16.08
•44
•19
•99
.86
.88
<6o
8.00
.15
.48
.82
.18
•55
•33
28.16
88.06
88.01
<6i
.05
.22
.56
.91
.28
.66
.47
.33
.«5
•23
162
.10
.27
.63
14.00
.38
•77
.61
•50
•45
.45
163
.15
.32
.69
.09
.48
.89
•75
.67
•65
.68
164
.20
.39
.76
.17
.58
1900
.89
.84
.84
.90
165
.24
.44
.84
.25
.68
.11
24.08
29.01
84.08
89.12
i66
.30
•50
.91
.33
.78
.22
• 17
.18
.23
•35
167
.34
.55
.98
.42
.88
•34
•32
•35
.43
•58
168
.40
.61
12.05
.50
.97
•45
.46
.51
.63
.80
169
.44
.67
.12
.58
17.07
.56
.60
.68
.83
40.08
170
.50
.72
.19
.67
•17
•67
.74
.85
85.08
.26
171
..S4
.78
.26
.76
•27
•79
.88
80.02
.23
.49
172
.60
.84
.33
.84
.37
.90
25.04
• 19
.42
.70
173
.64
.89
.40
.92
•47
20.01
.20
•36
.62
•91
174
.69
.95
.47
15.00
•57
.12
.36
•53
.82
41.12
175
.74
10.01
.55
.09
•67
• 24
•53
.71
86.02
•34
Inside
diam-
eter in
mm
Thickness of wall in millimeters,
i^ mm 2 mm 2^ mm' 3 mm 3^ mm 4 mm 5 mm 6 mm 7 mm 8 mm
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
.79
.06
.61
.17
.84
.12
.68
.26
,
.89
.18
.75
.35
^
.94
.23
.83
.44
18
•99
.29
.90
.53
9.04
.34
.97
.61
.09
.40
18.04
.69
.14
.46
.10
.77
.19
.51
.18
.85
.23
.58
.25
•93
.29
.63
.32
16.01
.33
.68
.39
.10
•39
.74
.46
.18
.43
.80
.54
•27
19
•49
.85
.60
.37
•53
.91
.67
.45
.59
.96
.74
•53
.63
11.08
.82
.61
.68
.08
.89
.69
•73
.13
.96
•77
.78
.20
14.08
.86
.83
.25
.09
•95
.88
.30
.17
17.04
•93
.36
.24
•13
20
•98.
.42
.31
.22
10.08
.47
.38
.30
.08
.53
.45
.38
.13
.59
.52
•46
.18
.65
.60
•55
.23
.70
.66
•63
.28
.75
.73
.72
•33
.81
.80
.80
.38
.87
.88
.89
.43
•93
.95
•97
21
.48
.99
15.08
18.06
.53
12.05
.10
• 14
.58
.10
.16
•23
•63
.15
.23
.32
•
.68
.21
.31
.41
.73
.26
.38
.49
,
.78
.32
.46
.58
.83
.38
.53
.67
.88
.44
.60
.75
,
.93
.50
.67
.83
22
•99
.56
.74
.92
11.03
.61
.81
19.00
.07
.66
.88
.08
.12
.72
.95
.16
.18
.78
16.02
.25
76
86
96
.06
16
25
35
45
55
65
75
85
95
.05
15
24
34
44
54
64
74
84
94
.04
14
24
34
44
54
64
74
84
94
.08
13
23
33
43
53
63
73
83
93
.08
13
23
32
42
52
.35
.65
.87
.46
.77
81.04
.57
.89
.21
.69
26.02
.38
.81
.15
.55
.92
.29
.72
21.08
.43
82.^6
.14
.57
.25
.71
•23
.36
.85
.40
.47
•99
.57
.58
27.18
.74
.70
.27
.91
.82
.42
88.09
.94
.57
.25
22.05
.71
.42
.16
.85
.59
.27
•99
.76
•38
28.18
.93
.49
.27
84.10
.60
.41
.27
.72
.55
.44
.84
.69
.61
.96
.83
.78
28.08
.98
.95
.19
29.12
85.12
.30
.26
.29
•41
,40
•46
•52
.54
.63
.63
.68
.80
.74
.82
•97
.85
.96
86.14
.96
80.10
•31
24.08
.24
•48
.20
•39
.65
.31
.53
.81
.42
.67
.98
•53
.81
8715
•64
.95
.32
.75
81.09
.49
.86
.23
.66
.98
.37
.83
25.10
.52
88.00
.22
.67
.17
•34
.82
.34
.45
.96
•50
.56
82.10
.67
.67
.24
.84
.78
.38
89.01
.21
.41
.61
.81
87.01
.21
.41
.62
.83
88.04
.25
.46
.67
.88
89.09
.27
.45
.64
.83
40.02
.21
.40
.59
.78
.97
41.16
.35
•55
.75
.95
42.15
•35
.55
.75
•95
48.14
.33
.53
.73
. -93
44.18
•33
.53
.73
.93
45.12
.31
.51
.71
.57
.81
42.05
.29
.53
•75
.97
48.19
.41
.63
.86
44.09
.32
.55
.78
45.00
.22
.44
.67
.90
46.18
.36
.59
.82
47.05
27
49
71
93
48.16
39
62
85
49.08
•31
53
75
97
50.20
43
66
89
.12
35
58
51
80
52.02
.24
.46
APPENDIX
159
Inside
diam-
•rhicki
eter in
mm
i}i mm
2 mm
2% mm
3 mm
Thickness of wall in millimeters.
$% mml 4 mm
5 mm
6 mm
7 mm
8 mm
225
226
227
228
229
230
240
250
260
270
280
290
300
310
320
330
340
350
360
370
380
390
400
410
420
430
440
450
460
470
480
490
500
600
•23
.28
.33
.38
.43
.48
12.46
.83
.89
.95
18.01
.06
.12
.6
%
14.25
.81
15.38
•95
16.52
17.08
.65
18.21
.77
19.84
•91
20.47
21.08
.60
22.17
•73
28.80
.86
24.48
25.00
.56
26.18
.69
27.26
.82
28.89
84.05
.08 .33
.15 .42
.22 .50
.29 .59
.36 .67
.43 .76
17.15 20.61
.85 21.46
18.56 22.81
19.27 28.16
.96 24.00
20.68 .85
21.89 2670
22.10 26.55
22.81 27.40
28.51 28.25
24.22 29.09
24.92 .94
2568 80.79
26.88 81.64
27.04 82.49
.75 88.84
28.46 84.18
29.16 85.08
.87 .88
80.58 86.78
81.2987.58
82.0088.48
.70
88.40
84.11
84.82
85.58
42.60
89.27
40.12
.97
41.82
42.67
51.15
.62 .89
.72 26.00
.82 .11
.92 .22
28.01 .34
.11 .46
24.10 27.59
25.09 28.72
26.08 29.85
27.07 80.98
28.05 82.11
29.05 88.25
80.04 84 88
81.08 85.51
82.02 86.64
88.01 87.77
84.00 88.90
84.99 40.04
85.9841.17
86.97 42.80
87.96 48.48
88.95 44.56
89.9445.69
40.98 46.82
41.91 47.95
42.90 49.08
48.89 50.22
44.88 51.85
45.8752.48
46.86 58.61
47.85
48.84
54.74
55.87
49.8857.00
59.7868.80
.52
.18
.66
.35
.80
.52
.94
.69
88.08
.86
.22
40.08
84.68
41.78
86.05
48.48
87.46
45.18
88.87
46.82
40.28
4852
41.70
50.21
48.11
51.91
44.58
58.61
45.95
55.81
47.86
57 00
48.77
68.70
50.19
60.89
51.60
62 09
58.01
68.79
54.48
65.48
55.84
67.18
57.26
68.88
58.67
70.67
60.08
72.27
61.50
78.97
62.91
75.66
64.82
77.86
65.74
79.06
67.14
80.75
68.57
82.45
69.98
84.14
71.89
86.84
85.54
102.81
.91
46.11
.31
.51
•71
.91
48.89
60.87
62.86
64.88
66.81
58.79
60.76
62.74
64.72
66.70
68.68
70.66
72.64
74.62
76.60
78.57
80.66
82.58
84.51
86.49
88.47
90.45
92.48
94.41
96.89
98.87
100.85
120.14
.68
.91
68.14
•37
.60
.83
66.58
58.84
60.60
62.87
65.12
67.88
69.66
71.98
74.19
76.45
78.72
80.98
88.24
86.50
8776
90.08
92.29
94.56
96.81
99.07
101.84
108.60
105.86
108.12
110.88
112.65
114.91
187.68
INDEX OF NAMES.
Acheson 76
Anderson 39
Andreoli 78
Bauer .... 39
Brandt 69
Brown 122,129
Buchholz 9
Burdette 131
Burgess 45
Chassy 3
Cowper-Colts 64, 91, 108
Davis 106
Dessolle • 63
Dumoulin 42, 1*5
Blectro-Metallurgical Co 46
Klectricitats-Aktien-G., V. Schuckert & Co 52
Blektrogravure G. I«td. Elmore 45» 75. 105, 117
Elmore, German and Austro- Hungarian Co 45, 47, 49. 53» 108
Elkington 76
Edruweit 61, 70
Engelhart 38, 46, 10, 104
Evans 106
Fletcher 38,91
Foerster 4, 22, 23, 26
Forsyth 91
Fox 76
Gerhardi & Co 49
Hall 133
Hampe 26
Hartig .22
Haubold 106
Hittorf 8
Holborn 29
HoU 44
Hoepfner 55
Huber 60
Hiibl, von 6, 15, 25
Jakobi I
Jordan i
Kennedy 122
Kick 15
KirchofF 37
Klein 93
Kohlrausch 29
Krueger 106
