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LIBRARY OF THE

SCHOOL OF ENGINEERING

SCIENCE CENTER LIBRARY

HARVARD COLLEGE
LIBRARY

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MONOGRAPHS

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 "L'Industrie electro-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 Socigte* d '^lectrochimie, Paris.

F. E. GUnther, 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, Registered Chemist, Essen.

Dr. K. Kellner, General Director, Vienna.

A. Krakau, Professor of the Electrochemical 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, Zurich.

Dr. R. Lucion, Director of Solvay & Co., Brussels.

A. Minet, Publisher of "L'ifclectrochimie, M 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.

MONOGRAPHS OF APPLIED ELECTROCHEMISTRY.

VOL. IV.

ARRANGEMENT OF

ELECTROLYTIC LABORATORIES

WITH SPECIAL REFERENCE TO THE
REQUIREMENTS OF

METALLURGICAL PRACTICE

H. NISSENSON

DIRECTOR OF THE CENTRAL LABORATORY OF THE
STOLBERG AND WESTPHALIA
COMPANY

AUTHORIZED TRANSLATION BY

JOSEPH W. RICHARDS, A.C., M.S., Ph.D,

PROFESSOR OF METALLURGY IN LEHIGH UNIVERSITY.
PAST PRESIDENT OF THE AMERICAN
ELECTROCHEMICAL SOCIETY.

E ASTON. PA. :
THE CHEMICAL PUBLISHING COMPANY.

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HARVARD UNT/fT'ITY

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Translator's Preface.

The rapid increase in interest in electrochemistry in
England and America during the last few years, and especially
the rapidly increasing importance of applied electrochemistry,
is giving rise to the need of more laboratories suitably arrang-
ed and properly equipped for studying electrochemical
problems.

The best guide for the erection of such laboratories is un-
doubtedly to study existing electrochemical laboratories, in
order to profit by the experience of pioneers in this work.
The thirteen laboratories described by Herr Nissenson are
fairly representative of European arrangements, while those
added by the translator, — that of the University of Wiscon-
sin, by Professor C. F. Burgess, and that of the Massachusetts
Institute of Technology, by Professor H. M. Goodwin, and
that of Lehigh University — will give a view of the arrange-
ments found suitable in America. As thus constituted, the
book ought to prove useful to anyone wishing to furnish an
electrochemical laboratory for almost any electrochemical
purpose.

The translator wishes to thank Professor Burgess and
Goodwin for permission to include their articles, also the
publishers of Electrochemical Industry for the loan of the
cuts to illustrate those articles, and further to thank Mr.
Walter S. Landis, Instructor in the department of Metallurgy
at Lehigh University for assistance in preparing the manu-
script for the press.

Jos. W. Richards.
Lehigh University,

January, 1905.

CONTENTS.

**fc

PAGE.

PART I.

i . Introduction i

2. Purpose and Value of Electrolysis r

3. Fundamental Ideas 3

4. Fundamental Laws of Electro-Technology 3

5. Calculation of Conductors 4

6. Components of an Electrolytic Equipment 5

(a) Source of the Current 5

(b) Measuring Instruments 6

(d) Conductors 8

(e) Switch-Boards 8

(f ) Work Room 9

(g) Space Requirements 9

PART II.

DESCRIPTION AND EQUIPMENT OP ELECTROLYTIC LABORATORIES.

1. Aachen 11

2. Breslau 13

3. Clausthal 16

4. Darmstadt 18

5. Freiberg, Saxony 22

6. Giessen 22

7. Hoboken near Antwerp (Desilverizing Works). 24

8. Konigsberg 29

9. Leoben 30

10. Central Laboratory of Dumont Brothers at Luttich 32

11. Munich 35

12. University of Pennsylvania 37

13. Stolberg, Central Laboratory of the Stolberg Company .... 41

The Electrochemical Laboratory of the Massachusetts Institute of

Technology. By Prof. H. M. Goodwin 51

Laboratory of Applied Electrochemistry, University of Wisconsin. By

Prof. Charles F. Burgess 63

Lehigh Univeraity. By Prof. T. W. Richards 79

PART I.

Introduction.

Although so much satisfactory material has been written upon
the value and importance of analysis by electrolysis, yet it has not
been appreciated, especially by our older colleagues, or they are
not yet acquainted with this field. Our younger colleagues, who
have had the good fortune to pursue their studies at a High
School, equipped with a chair of electro-chemistry, have lacked
on the one hand, the necessary experience to be able to judge of
the value of electrolysis to analysis, and on the other hand, be-
cause they mostly have only learned one system of laboratory
equipment for electrolysis, lack a general view of the various ex-
isting systems and methods, their advantages and disadvantages.

It seems to me therefore of the greatest importance to revert
to this method of analysis, and to describe anew the advances
which have been made and the experience gained.

I shall therefore in the present volume attempt to awaken fur-
ther interest in electrolytic analysis, by explaining its value and
purpose, offering a limited review of its present and possible scope
and finally to describe in detail, that which appears to me the most
suitable for metallurgical chemistry, upon the basis of eighteen
years of practical experience. I beg the forbearance of my ex-
perienced colleagues for detailing here the fundamental laws and
ideas, in a way the ABC of electricity, but it appears to me un-
avoidable for the complete attainment of the object of the work.

It is of importance that the business managers of mines,
metallurgical plants, etc., should be able to follow the presentation
and form an opinion of the matter, and they can then better appre-
ciate the efforts of the chemist. On this account, I have endeav-
ored to express myself in a way which will be generally under-
stood.

Purpose and Value of Electrolysis.

The purpose of analytical electrolysis is the quantitative sepa-
ration and estimation of the metals. It may be said that this pur-

2 ELECTROLYTIC LABORATORIES

pose is attainable by the older methods without the aid of the elec-
tric current, and that an equipment for electro-analysis is super-
fluous ; that this opinion is incorrect I will show in what follows
by a statement of the great advantages of electrolytic methods.

The great value of quantitative analysis by electrolysis for
metallurgical chemistry as well as also for the application of the
principles of chemical knowledge in practice, particularly for
large industrial operations, lies in the fact that with this method
of working the above purpose is attained more accurately, more
surely and in a much shorter time.

In fact this last advantage of quantitative analysis by electroly-
sis cannot be mentioned too emphatically. The fact is well known
that many estimations of metals, whose determination by the
older methods required many hours, as the estimation of lead,
copper, antimony, tin, cobalt and nickel in ores, the quantitative
determination of alloys, metallurgical products, etc., are now per-
formed by electrolysis in a few hours and with greater accuracy.
The value of this method is still further increased by the fact that
the chemist, during the real analysis, whose duration he knows ex-
actly after several experiments, may quietly finish other work;
that he may carry out a large number of electrolytic determina-
tions at the same time, with a sufficiently large equipment; and
that in certain tests he may by a single electrolysis simultaneous-
ly estimate two metals.

In large metallurgical operations, much depends on the obtain-
ing of accurate results in the analysis of ores in the shortest time.
It follows that those smelting works operate under the greatest
advantage which learn earliest the approximate value of the ore
content by means of the electroytic method, and in consequence
of this can purchase by telegraph most advantageously in the de-
sired quantity, before the ores are absorbed by another party.

It is also of the greatest importance to the smelter superin-
tendent to have the laboratory furnish him exact results in the
shortest possible time, that he may control and also correct in time
the operation of the metallurgical process in question.

The value of quantitative analysis by electrolysis to the sciences
follows from what has been said. It is well known that to-day all
large institutions are furnished with more or less complete equip-

INTRODUCTION 3

ments for analytical electrolysis; as Aachen, Breslau, Clausthal,
Darmstadt, Giessen, Konigsburg, Leoben, Munich, and many
others.

Finally, electrolysis gives to the student the possibility of observ-
ing and judging his analysis uninterruptedly, learning to recog-
nize and avoid errors and deficiencies, and enabling him to enter
into practice with a certain self-confidence in this line of work,
which to the same degree is impossible with the older methods.

Fundamental Ideas.

Before we go into a description of the equipment itself, we will,
for the reasons stated in the introduction, put forward the follow-
ing for an easier understanding of the subject.

The principal units of measurement in electricity are the am-
pere, the volt and the ohm.

The ampere is the unit of measurement for the mass or quan-
tity of the current, abbreviated to I = intensity, and generally
called "strength of current."

The volt is the unit for the measurement of the pressure which
pushes the current through the conductor (either metal or fluid),
abbreviated to' E = electromotive force, and generally called
"tension."

The ohm is the unit of measurement for the resistance which
opposes the flow of the current through the conductor, abbre-
viated to W in German (Widerstand) or R in English (resist-
ance) .*

Fundamental Laws of Electro-Technology.

The fundamental law of electricity (we are here only concerned
with direct currents, namely only those which always flow in the
same direction) is Ohm's Law, which reads

E = I.R [V = A.O]

or electromotive force (tension) = current strength X resistance,
or, transposed

T E T> E L V n VI

* [These three quantities are more logically designated as A, V and O
or O, the first letters of the units of measurement themselves. — Translator.]

4 ELECTROLYTIC LABORATORIES

The values and relations to each other of these electrical units
may be conceived best by a comparison with steam. The current
strength measured in "amperes" corresponds to the amount of
steam made per second, measured in kilogrammes; the tension
measured in "volts" corresponds to the steam pressure measured
in atmospheres, and the resistance of the path of the current or the
conductor, measured in "ohms" corresponds to the resistance
which the steam has to overcome in its conductors, or the fric-
tional resistance of the pipe walls.

If one with a steam pressure in a boiler (source of current) of
say two atmospheres (analogous to volts) can force an amount
of steam, say 20 kilogrammes (analogous to amperes) through
a pipe say 10 centimetres effective diameter and of a certain length
(analogous to resistance) in a unit of time, and then if — assum-
ing the necessary boiler capacity — the amount of steam in the
same time is to be doubled to 40 kilogrammes, the steam pres-
sure must be raised to 4 atmospheres, or if this is not possible,
then the area of the steam pipe must be doubled — one has a pic-
ture of the manner in which the corresponding electrical units are
related to each other. If 20 amperes (kilogrammes per second)
are passed through an electrolytic cell (conducting tube) with a
total resistance of 0.1 ohm (frictional resistance) by a tension of
the source of the current (boiler) of 2 volts (atmospheres), and
it is desired to raise it to 40 amperes, then the tension must be
raised to 4 volts or if that is not possible, the cross section (carry-
ing space) must be doubled, in order to halve the resistance, it
becoming 0.05 ohm.

Calculation of Conductors.

For calculating the necessary cross-section of the conductors
this simple formula is used:

L«I«o.oi6 f" Q L« A. 0.016"]

y - V L b ~ o J

where Q = the desired cross section of a copper conductor in
square millimeters, L the total length of the same, the sum of the
direct and return circuits, in meters, I the maxium intensity to be
carried (current strength) in amperes, V = the maximum al-
lowable tension loss in volts, and 0.016 the specific resistance of
copper at 15 C.

CALCULATION OF CONDUCTORS 5

Example : A conductor is required for an accumulator battery
of four cells ( = 8 volts) with a maximum discharge current of
40 amperes, the distance to the point of use being 15 meters, and
the allowable voltage drop to be 5 per cent., or 0*05 X 8 = 0.4
volt. Calculate the required cross-section of the copper wire.

^ 2. 15. 40. 0.016

q = -l_z = ^g S q # mm#

0.4

Component of an Electrolytic Equipment.

Source of the Current.
In the equipment of an electrolytic laboratory, the most import-
ant element is a source of current, which has to have the capacity
to furnish the required current to all the working places, for the
longest time required and at a voltage as constant as possible.
At the present time we have the following at our disposal :

1. Primary elements, namely those which in consequence of
their composition have the power to furnish current by changing
chemical into electrical energy.

For our purposes we need only concern ourselves with the
Meidinger and the Bunsen cells. The first gives a very weak cur-
rent so that even with a large battery only a slow precipitation of
metals can be attained; its electromotive force is about 1.1 volts,
and it has a somewhat high inner resistance. The latter gives a
strong current at the beginning which after several hours drops
off considerably ; they are not constant enough and besides evolve
injurious gases dangerous to health; their electromotive force is
at first about 1.8 volts and the inner resistance is very small.

2. Thermo-piles, of which the Gulcher is the most highly recom-
mended. This gives an electromotive force of 4 volts and has
an inner resistance of 0.65 ohm, and they are therefore best used
in practice in combination with accumulators, by the charging of
which during the night, the output of the installation is consid-
erably increased.

3. Accumulators or secondary elements, namely those which
store up . electrical energy furnished them, in the form of chem-
ical work and which in discharging transform it again into elec-
trical energy. Accumulators possess within their limits of capac-
ity the advantage of great constancy, and with a sufficiently large
electrode surface will give currents«of any magnitude, and there-

6 ELECTROLYTIC LABORATORIES

fore should not be absent from any good electrolytic plant. That
the battery may have long life it is essential to have it large
enough. The electromotive force of a cell is about 2 volts, and
the inner resistance is very small.

4. Dynamo machines, which can be obtained for any desired
output of amperes and volts, but in reference to the constancy of
their electromotive force are too dependent upon the constant
speed of their driving agent, and during their operation always
require a certain amount of attention, and therefore should be al-
ways combined with accumulators.

5. Connection with existing electrical lighting or power plants,
of private or public ownership. In reference to the constancy of
the electromotive force the same is true as was mentioned tinder
4, though possibly not to the same extent. The necessary accumu-
lators can only be charged by central stations by the use of re-
sistance, with the consequent loss of energy and expense, or in
relation to the amount of current used almost without cost by con-
necting in series in one or more of the arc light circuits of proper
current strength, and to prevent an overcharging of the batteries
in case of the short circuit of one or more of the arc lights, it is
necessary to interpose in the circuit an automatic circuit breaker,
in addition to the safety devices present in each generating sta-
tion. Finally motor-generators are suitable for charging accumu-
lators, transforming high tension currents of small intensity into
low tension high intensity currents. By the use of converters it
is indifferent as to whether the main current from the central sta-
tion is direct, or single or polyphase alternating. For these motor
generators the same remarks apply as to the dynamo.

Measuring Instruments.
After the selection of the source of current, the choosing of
suitable measuring instruments is of the greatest importance, be-
cause we can only hope for reliable results in electrolysis when
these re*ad correctly at all ordinary temperatures and over all
points of their scale, in short are instruments of precision. So
called commercial instruments are only applicable when they are
frequently submitted to an exact calibration, which, however, is
necessary from time to time even with instruments of precision.

MEASURING INSTRUMENTS 7

Another fault of the technical electrical instruments is that their
pointer does not come quickly enough to rest, while with instru-
ments of precision the desired value can be read off almost im-
mediately. Among the instruments of precision I mention here
the aperiodic, cased instruments of perfect construction made by
Hartmann & Braun and other firms. The large galvanometers,
etc., are more precise and reliable, although leaving out of consid-
eration their high price they are too susceptible to outside electri-
cal and mechanical influences, and require for their safe handling
a great amount of patience and experience. An ammeter is nec-
essary for the measuring of the current strength, and a voltmeter
for the measuring of the electromotive force, and it is also de-
sirable to have another ammeter, reading both ways from zero,
for measuring the charging and discharging current, and which
can also be used as an indicator of current direction. With the
exception of this last instrument which is always put directly into
the circuit, it must be decided whether one prefers to measure the
current strength in the main circuit or in a shunt.

Measuring in the first manner, namely the direct measuring,
is decidedly preferable because of its simplicity, and therefore
greater accuracy. The second method, namely the indirect meas-
uring, is preferred where there is a large number of work places
involved, and where by correct use errors of measurement
through wrong connections are almost impossible. For large
works there is also recommended the installation of a watt-meter
for the purpose of calculating the costs in the separate depart-
ments.

Current Regulators.

As important as the measuring instruments are the current
regulators, the adjustable resistances which are intended to bring
and maintain the current and tension at the right values at the
respective electrolytic baths. These regulators must have a wide
adaptability, and a great number of steps, in order to be able to
vary the amperes and the volts at the baths within a wide range,
which is indispensible on account of the variety of the baths.
Wire resistances with large contact points, fastened in iron frames
on slate and marble, are to be preferred.

All incandescent lamp resistances and plug boxes or similar

8 ELECTROLYTIC LABORATORIES

construction must be classed as unreliable and unsuitable because
of too small range of variation, poor contacts even with careful
construction, and other deficiencies.

Conductors.

The conductors must as is to be seen from the preceding have
a sufficient cross section of copper that the loss of voltage is re-
duced as low as possible. I once had the opportunity to visit a
plant which lost one volt, between the source of current and the
electrolytic work table, the fall amounting in this case to 25 per
cent. Even in the best plants there is an unavoidable drop of
voltage through contact resistance (as where the current goes
from one contact surface to another) so the cross section of the
copper is made from 15 to 25 per cent, greater than the calcula-
tion would require. Concerning the outside of the conductors, it
is recommended to use wires or cables insulated with seamless
vulcanized rubber, and then coated for protection, and fastened
to large porcelain insulators. Naked wire may be strung on large
porcelain insulators and covered with a coat of acid resisting
paint for protection from the laboratory fumes, though there is
great difficulty in preserving this protecting coat at the binding
posts due to the abrasion there.

Switch Borads,

The switch board should be placed immediately over the elec-
trolytic table, and should be large enough to contain all the meas-
uring instruments, current regulators, and switching apparatus,
mounted in such order as to be easily understood and simply
operated. For protection from the dampness the whole board
should be enclosed in a tight case with glass doors, which to econ-
omize space should be of the sliding order. The most suitable
material for the board is white well-polished marble, free from
metals, which has the advantage over slate in not being so hy-
groscopic. The size of the switch board depends, as also the size
of the source of the current, accumulator batteries, regulators and
switching apparatus, upon the kind of work to be performed, and
the number of working places.

WORK ROOM

Work Room.

After reaching a final conclusion on these questions, we are
ready to consider the selection or (if building) the designing of
the work rooms. There should be at least two rooms, one solely
for electrolysis and for the switch board and accumulators (in
an alcove) and the second room for the dynamos, with their mo-
tive power (steam, gas or water motors), or for the converter
when connection is made with a central station. This second
room can only be dispensed with when connection with an arc-
light circuit is possible, in which case it is pre-supposed that there
is a sufficient number of lamps burning all night. This is gener-
ally the case in large works.

In reconstruction and large plants designed for the purpose of
instruction, four rooms should be allowed, one for the dynamo
with its motive power, one for the accumulators, one for work,
as electroanalysis (possibly two more for use in metallurgical
and galvanic plating) and the last one for the balances and for
writing purposes.

Space Requirements.

The necessary floor space for normal conditions of the engine
room is 20 square metres for either steam (without boiler), gas
or water power; with converters about 4 square metres; an ac-
cumulator battery of four cells furnishing 60 amperes requires
about 4 square metres; and a battery suitable for metallurgical
purposes and the like, that is for very heavy service about 20
square metres, if the cells are all placed in the same plane, which
is desirable for an easy access. If the cells are placed in two
rows, one over the other on wooden supports, only half the floor
space will be required.

The work room for electrolysis will require, including the labor-
atory tables, about 16 square meters for four work places; and
the same amount of space will be required for the metallurgical
and galvanic testing equipments.

The space required for the balances can be adjusted to local
conditions and the requirements of the chemist, but will require
at least 16 square metres.

The rooms should lie as close as possible to each other and

10 . ELECTROLYTIC LABORATORIES

communicate through doors, with the exception of the accumula-
tor room, which should open to the outside only, so that the gases
evolved cannot pass into the other rooms. To avoid loss of energy
the battery room should be adjacent to the working room. All
rooms should be high, well lighted and well ventilated, and be well
equipped with gas and water taps at all the working places, and
besides good artificial lighting each table should be equipped with
a small water, hot-air or electric motor for driving stirring appa-
ratus. With the exception of the accumulator room all rooms
should be connected with the existing steam heating system, or
else otherwise comfortably heated.

PART II.

In this part we will describe a limited number of existing
plants for electrolysis. In order to avoid obscurities we will limit
these descriptions to the more important points and, as it becomes
necessary, add drawings. I could have included many other
plants, but that was unfortunately impossible because of insuffi-
cient knowledge with regard to certain details.

However, it will be quite possible to <Jraw from the examples
given a picture of the manifold arrangements of this kind of plant,
and in case of necessity, to construct from them general directions
for the choice of the system best suited to the particular case.

At this point we will not omit to express our sincere thanks to
the gentlemen who so willingly placed the information in our
hands.

Aachen.

The Electro-chemical Institute of the Aachen High School,
which is under the direction of Professor Classen, uses as a source
of current the three-wire direct-current system of the municipal
electric plant. The high tension direct current taken therefrom,
of 2 X 1 08 volts is transformed by means of a rotary transformer
into current of 8 to 12 volts, and is as such either directly used or
is stored up in a large accumulator battery consisting of 4 ele-
ments of 60 amperes maximum discharge current and 180 am-
pere-hours guaranteed capacity, and thence conducted by heavy
insulated wires to the twenty work places provided. Besides the
large battery there is in addition a small one likewise of 4 cells
and of 20 amperes maximum discharge current. The cells of
both batteries may be used, if so desired, in pairs in parallel for
heavy currents, or in series for tension.

Each working space carries over it a board upon which are
placed the handles for the regulating resistance, the double-pole
lead fuse to protect the apparatus and transformers against over-
loading, the cut-out switch, an ammeter switch, a voltmeter
switch, as well as two binding posts marked + and — for con-

ELECTROLYTIC LABORATORIES

necting with the electrolytic cells. The resistance belonging to
the regulating handle is placed in a closet under the table, for
protection from vapor. The conductors upon the table are placed
inside a double walled back-board so that only the four appara-

Figr. i.

tus and the two binding posts are visible. The fuses, the main

AACHEN 13

cut-out switch and the ammeter switch are provided with protect-
ing covers.

Each working place is provided with an ammeter with a scale
from o to 3 amperes in both directions and divided into 0.1 am-
pere, and a voltmeter with two scales with a range of o to 5 and o
to 10 volts respectively. These instruments are provided with
particularly large scales of 16 centimeters radius, in order to
make possible readings at comparatively large distances.

The connections between apparatus and instruments are set forth
in the wiring plan of Fig. 1 ; -f- and — designate the main con-
ductors coming from the accumulators. At the working places
I the current goes from + through the safety fuses S to the cut-
out switch A, to the resistance W with the regulator R, to the
cell Z, and from there over to the other pole of the safety fuse S
and to the ammeter switch A-U, and thence to — , while the volt-
meter switch V-U in combination with the voltmeter wires E-L
allows a measurement of tension. The measurement of the cur-
rent used by the cell or of the work expended upon the bath with
a determined measured current strength is shown by the posi-
tion of the switches in Fig. 2. At this place the current passes
from -f- through S-A-W-R-Z and S up to A-U, by the same path
as in I; it is then, however, taken by the reversed throwing of
A-U directly through the ammeter wires J-L, in this way to the
ammeter.

The plant was installed by the firm of Schuckert & Co., of
Niirnberg.

Breslau :

Zeitsch. f. Elektrochem., 1897-98, 552.

When the Chemical Institute of Breslau was rebuilt in the year
1896, a laboratory with 24 places for electrochemistry was in-
stalled.

The necessary current was taken from the city power plant at
a tension of 1 10 or 220 volts and by this means and the use of a
main current regulating resistance (see Fi^. 2) two batteries of
accumulators were charged, one of which, containing 36 cells, was
used entire for particular purposes, and especially for supplying
the large lecture room, while the other consisting of 30 cells (see

ELECTROLYTIC LABORATORIES

SJ5

^ i

"■■» *■■ ■> ^ — K

BRSSI^AU

Fig. 3) was divided into several groups and served as the source
of direct current for the electrochemical room. In order to be
able to take varying electromotive forces from this battery five
elements were united into one group, one group of which is sub-
divided into single cells. The poles of these single cells as those

nd flewctonce

Fig 3a.

Fig. 3b

of the five single groups end at the switch-board in small brass
blocks, and here end also the conductors which lead to the single
work tables. Thus it is possible to connect the latter by using
flexible conducting cables in many combinations with the fixed

ELECTROLYTIC LABORATORIES

contacts (Fig. 3a) and with the various parts of the battery so
that any desired voltage may be had.

Since the five single elements of the battery will naturally be
most used the switches are so arranged that this part of the bat-
tery may be charged alone. The finest measuring instruments
and particular apparatus needed for investigation are placed in
each case for the experimenters and arranged for use upon the
working places (Fig. 3b). The measuring instruments for use

with the battery are placed with the other necessary apparatus
on a switch-board so that they may be used for measuring any
single discharge current.

The accumulators are set up in the cellar of the Chemical In-
stitute.

Clausthal :

Zeitschr. f. anorg. Chem., 26, 167.

The chemical laboratory of the Mining Academy at Clausthal
takes its primary current of a maximum strength of 15 amperes

e UUUU.U.1.L1.UI, 1

rrrrrrrrrrrrmT ki

Fig. 4.

fi— ii c

rU n

ITTe VTw win

l/J Iff \d Vi

Fig. 5.

from the city circuits and either uses it directly for experimental
purposes or charges with it a battery of accumulators without
the introduction of any resistance but merely with the introduc-
tion of safety fuses and an automatic low-current cut-out. The
battery consists of 48 cells each of 22 amperes maximum dis-
charge current strength and 90 ampere-hours guaranteed capac-
ity. The battery is divided into 16 single groups of 3 cells each
and 32 groups of wires lead from its location in the cellar to the
contact apparatus (Figs. 4 and 5.) mounted on the ground floor.

CI^AUSTHAI,

This contact apparatus consists of a switch-board 120 X 30
centimetres and 60 centimetres thick which has been boiled in

Direcf cAan£/)7& w/Mout resistance.

HH y HHii

Jdafteri/ uri/A Vtfcetts.

660 OOOooOo o OOO

kD 1 ^) OOOOOGOOGOOO

H-hrf-Hi

C/tar&sir& $u//fc6 covtr wtfr COjoper A>ow*.

•Automatic .
Zero cuhout switch.

JJPrrxcfjoa/ cuho«t *w/fcA.
Prtnct&ai <S#fet(/ fuses.

2j^g^fit£t£fi^B4AB™^i

Fig. 6.

paraffin, and has 32 circular holes, arranged in two parallel rows,

1 8 IvI.ECTROI.YTlC I^ABORATORIES

corresponding to the 32 wires, and further two holes each for the
principal charging and discharging conductors. These 36 holes
are filled with mercury. For connecting the batteries for charging
and discharging at the determined current strength of 22, 44, 88,
l 7&> 35 2 amperes at 96, 48, 24, 12 or 6 volts, respectively, wooden
forms are used with the corresponding labels, upon the under
side of which copper bows are attached of such form, strength
and position that they only need to be dropped down between
corner guides upon the connection board in order to furnish the
system of connection designated by its label. The wiring plan for
direct charging of the battery without resistance may be seen in
Fig. 6.

Two wires lead the main current to the switch-board, while
others lead the discharging current to the distributing switch-
board on the first story, from whence the distribution is made to
the auditorium, the four work places, the private laboratory, and
the iron metallurgical laboratory. For obtaining small currents
at tensions under 6 volts, as well as for electrical measurements
10 small accumulators are provided, which are connected in pairs,
as small transportable batteries ; these are connected in series and
charged over night by the large battery at a tension of 24 volts.

When carrying out an electrolytic operation a student is given
a place provided with an ammeter, a voltmeter, a rheostat, and
binding posts, so arranged that the necessary connections in the
circuit can be easily observed. The student thus needs only to
place upon his work table the electrolysing stand and to connect
this with the poles of the main conductors above each working
table and then proceed with his analysis.

Darmstadt.

The eletrochemical laboratory of the Technical High School
at Darmstadt produces its own current in its own electric power
plant placed in the basement of the building where the noise from
the machinery cannot annoy any one. The plant is provided
with a direct current dynamo giving either 500 amperes at 12
volts, or by changing the circuit 250 amperes at 24 volts. The
cables from the dvnamo machine are conducted to a main switch-

DARMSTADT

board in the same room so that all regulating and changing of
circuits of the dynamo can be conveniently performed from this
point. The current furnished by this dynamo is used either to
charge a battery of 5 cells having a discharge capacity of 500 am-
peres or for a second of 36 cells of 300 amperes capacity. In the
first case the armature windings of the dynamo are put in parallel
so that the machine gives double current strength at single ten-
sion. For charging the 36 cell battery, the armature windings
of the dynamo are connected in series; that is, to give a single
current strength at double tension, and the battery is then divided
into single groups. All the required apparatus and instruments
are placed upon the main switch-board, to which the batteries,
likewise in the cellar, are also connected by a corresponding
number of conductors.

Besides this the plant also contains an alterating current
dynamo of a capacity of 60 amperes at 100 volts, and a trans-
former for current at 10 to 1,000 volts divided into convenient in-
termediate intervals.

-5 X!>*CUw

Fig. 7.

From the main switch-board the current is led to the main cur-
rent measuring room on the ground floor, and is thence under
skillful supervision divided up and furnished to the working
places in the strength and at the tension required at the time. This

20 ELECTROLYTIC LABORATORIES

division and regulation of the current from the main power house
to the working places is accomplished by means of a so-called
line controller, the construction of which is shown in Fig. 7. The
two lower horizontal copper strips are connected with the five cell
battery and therefore give 500 amperes at ten volts tension, the
two upper ones to the 36 cell battery and give therefore up to
300 amperes at 72 volts. The vertical strips are connected with
the upper and lower horizontal strip by the plugs shown in the
drawing and then conduct the current, after passing through
lead safety fuses, by means of insulated wires to the working
places. These conductors are made so large that even with the
highest currents an energy loss of 5 per cent, in the conductors is
not exceeded, and in this way disturbances of neighboring ex-
periments are as far as possible avoided. In the measuring room
there are also delicate instruments of precision which as needed
may be placed in one or the other working circuits.

In two rooms on the ground floor and the first story above
there are 40 working places. Each work table has a regulating
resistance mounted in a closet under the table to protect it from
vapors, and a voltmeter and ammeter which are placed in a sepa-
rate glass case.

DARMSTADT

22 ELECTROLYTIC LABORATORIES

In general only 20. amperes are available for each working
place. Yet the measuring instruments as well as the regulating
resistances and the lead fuses are arranged so as to be easily re-
placeable in oredr that, if necessary, instruments for large cur-
rents may be put in their places.

In the private laboratory of the head of the department, Prof.
Dieffenbach, there is also a large line controller, the outside of
which is shown in Fig. 8. In this the horizontal strips are also
connected with the source of current while the vertical strips con-
duct the current, by using the proper plugs, to the desired work-
ing places. For the avoidance of overloading by short circuits,
etc., the distributing conductors are provided with lead fuses.
This controller allows of the taking off of direct or alternating
current in six different ways.

Freiberg, Saxony :

Chemiker-Zeitg., 24, 56, 1900.

The electrolytic laboratory at Freiberg, Saxony, uses a Gulcher
thermopile as a source of current, and with it charges an accumu-
lator battery of four cells.

The switch-board is placed directly above the electrolysing
table and contains the following apparatus, serving for four
working places : an ammeter of precision reading up to 5 amperes
by 0.01 ampere and a voltmeter of precision divided as the above
up to 10 volts, a circular crank regulating resistance, a plug
switch for the measurement of the current, a common plug
switch for the measurement of the voltage, and two binding posts
for the connection of the cells.

All the conductors lie on the front side of the switch-board to
show their use clearly, for which purpose they are also insulated
in colors, the wires to the working rooms being green, for cur-
rent-measuring are red, for voltage measuring blue, etc. Fig. 9
gives a clear idea of the equipment.

Giessen :

Zeitschr. f. Elektrochemie, 1 899-1900.

At the Electrochemical Institute in Giessen, Professor Elbs
erected a private plant, which uses as driving power a 16 horse-

GIESSEN

power gas engine. This runs a demonstration dynamo which can
furnish either direct or alternating current. For the electrolytic
work itself (the dynamo is used also for lighting) there is an ac-
cumulator battery of 9 elements of 1200 ampere-hours capacity
and a maximum discharge rate of 590 amperes, which is charged
by means of a converter wound for an output of 200 amperes at
20 volts (see Fig. 10).

DYNAMO zs

If MQTOR+sV

Fig* 10.

The battery is divided into three groups of respectively two,
three and four cells in series, by which tensions of 4, 6, 8, 10, 14
and 18 volts may be obtained. See Fig. 11.

nmnmnn

Corresponding to the above grouping of the battery four wires
lead to each working place, which are calculated for a maximum
current of 25 amperes.

24 ELECTROLYTIC LABORATORIES

Each working place has a three-storied superstructure for the
accommodation of the regulating resistance, the ammeter and the
voltmeter, and at the side of the shelves are the binding posts for
the connection of the cells to the current conductors.

Desilverization Works at Hoboken near Antwerp.

This plant, used only for practical purposes, employs as a
source of current, an old accumulator battery on hand at the time
of remodeling, and a new one consisting of four cells with a maxi-
mum rate of discharge of 30 amperes and a maximum capacity
of 132 ampere-hours, on a 10 hour discharge rate at 13 amperes.
Both batteries are charged from the lighting plant at the works
by the interposition of a resistance. The apparatus equipment is
designed for eight working places. Fig. 12 gives a clear view of
the arrangement, which will be still further explained in the fol-
lowing :

Three switch-boards, M 1} M 2 , M 3 , of white marble free from
metals, are built in a large oaken frame 3 metres long and 1.25
metres high.

The measuring instruments Amp. and Volt with their
switches Amp. Umsch and Volt Umsch are placed on the
middle board M 2 so that they may be easily connected to
and read from each working place. The voltmeter Volt is
an aperiodic precision instrument with a reading range from
o to 12 volts with a scale of equal divisions in tenths of a
volt. The aperiodicity (dead beat quality) of the measuring
instruments for such purposes is of great value in order that they
may quickly come to rest and can be accurately read off. Con-
nected directly with the instrument is the double-pole voltmeter
switch Volt Umsch, which is placed in the middle of the
switch-board M 2 because being most frequently used. The switch
consists of two sectors of circles x + and x — , which are con-
nected to the binding posts of the voltmeter by two wires, and
the 2 X 10 contacts be arranged in the form of an arc, of which
eight with their eight diametrically opposite contacts lead by
means of heavy insulated conductors of negligible resistance
straight to the binding posts BK of the baths. Over the centre
of the contacts is a heavy pivoted handle of ebonite which at each
of its two ends carries heavy contact brushes, one sliding over the

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o o o

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26 ELECTROLYTIC LABORATORIES

sector contacts x and the other over the contacts C and uniting
these metallically directly with each other. If the handle is placed
for instance in contact with C 4 then the voltmeter will indicate
the tension across the binding posts of the bath 4. The contacts
C 9 and C 10 are in connection with the main switch H — U and
enable the electromotive force of both the old and the new ac-
cumulator batteries to be read off.

The main switch H — U is a double-pole lever switch whose
blades are pivoted at the middle clamps v x which are in connec-
tion with the distributing conductors. When the blades are
thrown over to the upper contacts a x current is taken from the
old battery, when thrown over to the lower ones u x the new
battery furnishes the current. When no work is being performed
the handle is thrown straight out at right angles to the drawing
where it is held by an arrestment. Thus the switch also serves as
a make and break switch. For measuring the current an aper-
iodic precision ammeter Amp. with a scale of equal divisions from
o to 6 amperes and divided into 0.05 ampere is used. This in-
strument is not, however, used to measure the whole current di-
rectly, for by so doing larger or smaller errors are unavoidable
according to the skill with which the switching plant has been
built and is used. Rather it is preferable to use it as a shunt in-
strument traversed only by a part of the whole current. This
manner of measuring is designated as indirect, and that in gen-
eral use as direct measurement. Fig. 13 shows this last method
applied to a single circuit, and Fig. 14 the same applied to several
working places. Figs. 15 and 16 show the indirect method ap-
plied respectively to one or more working places. A comparison
of the figures shows at once the superiority of the indirect method
with the direct in reference to precision of measurement, es-
pecially with the application of a single concentric ammeter switch
for all the baths. The greatest possible accuracy will be attained
when the total resistance of the adjacent or distant bath-circuits
remain unchanged whether the ammeter is in circuit or not,
which is attained by putting the ammeter of relatively higher inter-
nal resistance by means of the ammeter switch only in shunt at
the terminals of standard shunt resistances S introduced into
each current circuit. These shunt resistances are all alike and of

DESILVERIZATION WORKS AT HOBOKEN

+ I

-*vwvvvA-

28 ELECTROLYTIC I^ABORATORIES

very small resistance which bears an accurately determined rela-
tion to the resistance of the measuring instrument, so that the
measuring instrument is traversed by a certain fraction of the
current passing through the bath, the latter being calculated by
the formula,

Jm w, + w/

in which Jm is the current flowing through the instrument Jv
the current passing through the bath, Ws the resistance of the
shunt, and Wra the internal resistance of the instrument.

To attain really accurate results it is indispensible that the con-
ductors between Amp. and Amp. Umsch on the one side and
Amp. Umsch and the shunt on the other side should have exactly
the same very small resistance, for which purpose this re-
sistance should be determined before they are fastened to
the switch-board. The double-pole ammeter switch, which is
constructed exactly like the voltmeter switch Volt Umsch,
avoids absolutely the danger of the error that the sum of the cur-
rent strengthrent strength of two given baths may be measured
for one, because the lever of Amp. Umsch can only touch the con-
tacts of a single bath at one time.

Besides the above described apparatus the switch-board carries
eight reversing switches, eight bath-current regulators and eight
pairs of bath binding posts which according to the space available
are divided among the marble tablets M lf M 2 , M 8 .

The double-pole reversing switches serve for reversing the cur-
rent, a requirement which is necessary in certain cases, and which
saves the annoyance and time-consuming disconnection when by
oversight the bath is connected up wrongly, which often happens
in practice. The arrangement of the poles is the same as in the
above described main switch H-U, only it is smaller because of
smaller currents. The middle terminals lead the current away to
the baths, the upper and lower ones bring the current ; above the
right one is + and the left — , below the right — , and the
left +.

The bath current regulators have in the case in question a
total resistance of 40 ohms divided into twenty, some large, some
small steps.

DBSILVERIZATION W<Mj$f» .^

LABORATORIES

mp-cvt-cutsuHteh l, P/metf

r© i

\auci. tf

e cut-cut tu/iteA.

onam

/2er ent//r6 Witch, f famviM StritcA, ftererging stritch.

***i?i?l nn?T Fin

DESILVERIZATION WORKS AT HOBOKEN 29

They consist of rectangular cast iron frames on which are
strung resistance spirals which are connected in suitable sections
with contacts arranged in the form of an arc of a circle on a
slate board. In order to regulate these resistances, there is pivot-
ed a long contact arm of large radius, and therefore easily moved,
upon a fixed axis at the opposite end of the frame, the axis serving
likewise as a contact. Underneath the regulators are the binding
posts BK for the baths from which flexible double cables covered
with rubber lead to the stands. The two wires of the double
cables are differently colored so as to differentiate their polarity.
The whole installation including the return conductors is protect-
ed from the laboratory fumes by a tightly closed oak case from
which only the last named double cables lead out. Three tightly
closed glass doors are placed on the front of the case, through
which the measuring instruments and their connections may be
seen.

Beneath the apparatus case there is hung a case of shelves,
which are covered with thick glass plates for protection from
•damage by acids. The case, as made by me, had two shelves ar-
ranged step-like one above the other. On the lower one, after the
electrolysis is complete, a glass vessel can be placed into which
the electrolyte can be siphoned in a simple manner.

The installation was designed and built by the firm of Raacke
Brothers, of Aachen, in the fall of 1899, who packed it in such
shape that it was only necessary to hang the shelves and closet
in place in order to be at once ready for use.

• • •

Konigsberg.

The present electrolytic installation of the Chemical Institute
at Konigsberg was completed in the winter of 1899/1900 under
the direction of Professor Blochmann. It is arranged for four
working places.

The source of current is an accumulator battery of four cells
of the same capacity as those at Hoboken which are charged from
the city plant through resistances. The measuring and the switch-
ing arrangements are the same as those at Hoboken, except that
"here a second ammeter with a large-range scale is permanently
placed in the main circuit without an individual cut-out switch

ELECTROLYTIC LABORATORIES

and serves for the control of the current consumption of all the
baths.

The accompanying figure, Fig. 17, shows the external arrange-
ments of the installation.

Raacke Brothers of Aachen designed and installed the plant.

Loeben :
Osterr. Zeitg. f. Berg. u. Hiittenwesen, 46, 1898.

The laboratory equipment of the Imperial Mining Academy at
Leoben demonstrates that it is possible to carry out investigations
on a small scale in such places as are without a city power supply
or one of their own for the disposal and distribution of the cur-
rent. A Gulcher themopile is used as the source of current; it
consumes 170 litres of gas per hour and gives a current of 3 am-
peres at 4 volts.

Pachy trop .

Tig. 18.

Six accumulator cells are charged by this, each having a dis-
charge rate of 2 amperes and a capacity of 18 ampere-hours.

For connecting the cells for tension or current strength, or con-
necting singly or in groups in parallel or series, the Institute uses
a so-called Pachytrope after Daurer. Such a Pachytrope con-
sists, corresponding to the number of cells concerned, of a num-
ber of contacts mounted on an axle, and capable of being rotated
by means of a handle, sliding between metal teeth which connect

32 ELECTROLYTIC LABORATORIES

copper segments. According to the distance which the discs are
turned and according to the use of certain discs, one can have at
his disposal the desired current at the desired tension.

From this switching arrangement the current is conducted to
two working places which are on the same table with the above
described apparatus. Both working places have a plug resistance
box and a double-pole mercury switch, one side of which con-
nects the cell with the voltmeter and the other side with the am-
meter. Both measuring instruments together with a rack for rea-
gents are on the wall over the table, so that the total equipment is
assembled above and upon this one table. Figs. 18 and 19 pre-
sent a clear outline of the scheme of connections and equipment.

Central Laboratory of Dumont Brothers, Luttich.

The equipment for electrolysis in this case is likewise for the
practical purposes of a laboratory connected with a large
metallurgical works and is built after the same principles as that
of Hoboken. Differing, however, from the latter are the means
for producing current, which will be described more in detail here.
Aside from this Fig. 20 shows the equipment intended for six
working places.

The laboratory uses as a source of current the existing con-
nections for lighting purposes to the city lighting plant of 2 X
105 volts direct current (three wire system). The current taken
from the outside conductors of the three wire system at A (see
Fig. 21) at 2 X 105 volts tension, passes first through a double
pole lead fuse B, a double pole main switch HA and the watt-
meter Z; from here it is led by rubber covered wires of copper
having a cross section of 5 square millimeters, and carried by por-^
celain insulators, to the transformer switch-board T-S in room I
(see Fig. 22) and then conducted to the converter T through the
regulating resistance A-W.

The converter is of the rotary type, consisting of a direct cur-
rent shunt wound motor rated at one horse-power at 220 volts
and mounted on the same cast iron bed plate with a direct current
shunt wound dynamo to which it is directly coupled through a
flexible leather coupling, and which at 1000 revolutions per min-
ute furnishes 40 to 50 amperes at 12 to 9 volts tension. The cur-

LABORATORY AT LUTTICH

bi
to

■5

34 ELECTROLYTIC LABORATORIES

rent from the dynamo is regulated by the use of a shunt control-
ler either for direct use at 8 volts or for charging storage batter-
ies at 12 volts, and then passes through a double pole 50 ampere
fuse from which point it is led over to room III by rubber cov-
ered copper conductors of 35 square millimeters cross section
strung on large porcelain insulators. In the same room in an al-
cove A-K is the accumulator battery A-B. This consists of four
cells with a maximum discharge rate of 30 amperes and a maxi-
mum guaranteed capacity of 132 ampere-hours when discharged
at the rate of 13 amperes for ten hours.

In general the accumulators are used for electrolysis because
of their constant tension, and are charged as follows. First, the
switch HA is closed into the main line and then gradually by
means of the starting resistance AW the motor side of the con-
verter is cut in until the latter is at full speed and then the shunt
regulator KR of the dynamo side is brought into circuit until the
voltmeter registers 12 volts. The charging switch L-S on the
main switch-board is now closed and the charging begins, the
current strength being controlled according to the indications of
the ammeter. This instrument of precision is of the same
type as those used at Hoboken and has its zero point in the mid-
dle of the scale so that it can also be used at the same time as an
indicator of the direction of the current ; that is, when the needle
points to the right the battery is charging, when to the left it is
discharging. In order to use the instrument to better advantage
it is connected to the ammeter switch, so that it is possible by
turning the handle, to switch on to a shunt on the bath circuit, and
so with the same to measure the total current simultaneously used
by several baths whether they are taken directly from the dynamo
or indirectly from the battery.

If it is necessary to perform electrolysis during the charging of
the battery the main switch is thrown over to the right, and there
is received the direct current of the dynamo at the charging ten-
sion used. This method of operation is recommended as econom-
ical, because in this way a loss of energy in the accumulators
amounting to 20 per cent, is saved, aside from the excess voltage
necessary for charging. This overvoltage which has to be neutral-
ized in the bath circuit regulators ceases as soon as the charging

\*i * *

-SMH-

ELECTROLYTIC LABORATORIES

above is a large accumulator battery of 30 cells with a capacity
of 180 ampere-hours, and a small battery of 4 cells and capacity
of 120 ampere-hours.

The large laboratory on the first floor has 27 working places
which, with the exception of two, contain no other apparatus than
the plug contacts for connecting the decomposing cells. The
switching in and out and measuring and regulating of the current

TTTTTT
TctAe wcrfi tables.

Fig. *3-

for all these working places takes place in the adjoining switching
and measuring room. Only the so-called general table No. 9
and a single table in an alcove possess each their own current reg-
ulators at the place and the first several small measuring instru-
ments for direct and alternating current.

MUNICH 37

For distributing the current there is a large switch-board
which covers one whole side of the above mentioned switching
and measuring room. (See Fig. 23). It consists of a black slate
board containing 29 horizontal copper strips for bringing in the
current and 2 X 27 vertical strips, corresponding to the number
of working places, for leading off the current: each is mounted,
with a small space between. The latter are provided with a suit-
able number of tapped holes so that one can obtain at each work-
ing place current of the desired tension and strength from each
of the sources which are provided ; that is, either with direct cur-
rent 60 to 90 volts (direct from the dynamo), alternating current
of 50 volts, the same transformed from 2 to 100 volts (the ten-
sions of 1,000 and 10,000 volts are not accessible to the student),
and also with accumulator currents of 2 to 8 or 10 to 66 volts.
Underneath this system of strips are 12 crank current regulators
mounted upon projecting brackets, and which may be connected
with the respective working places by screw plugs. Each regula-
tor has two contact circles with swinging cranks, capacity 12 am-
peres; the one for interposing resistance from 0.1 to 10 ohms, and
the other from 10 to 50 ohms ; so that any resistance from 0.1 to
50 ohms can be switched into the circuit, thus satisfying widely
varying requirements.

The institute possesses a special room for fine measurements,
there being at disposal an Edelmann's absolute electrotechnic
galvanometer for 200 amperes, and a Siemens' torsion galvan-
ometer for 0.01 to 170 volts. The same room also serves for the
preparation of ozone and Rontgen investigation. [The production
of ozone in the room where standard instruments are kept is not
recommended by the translator.]

We must not overlook the fact that the laboratory is ventilated
by three large electrically driven Blackmann ventilators.

The dynamos were furnished respectively by Schuckert, Gen-
eral Electric Company, and Siemens, and the switching and con-
ducting equipment was furnished and installed by the General
Electric Company.

University of Pennsylvania.
Elektrochem. Zeitschr., 8th year, No. 9.
The electrochemical equipment of the Chemical Department of

ELECTROLYTIC LABORATORIES

the University of Pennsylvania has been in use since the year
1878, and at that time, as was the case with all the older installa-
tions, used for the source of current primary cells. Owing to the
inefficiency of these cells and also to the development of the sec-
ondary elements (accumulators) to a state applicable to practice,

UNIVERSITY Otf PENNSYLVANIA 39

a battery of cells of the Julien type was installed in 1888, and
was afterwards replaced by a number of chloride accumulators.

The switching arrangement (Fig. 24) of the older plant is in-
teresting. The figure shows only a portion of the whole (because
of the limited space) but it is enough for our purposes of expla-
nation.

A to F are secondary elements, whose positive p6les are con-
nected when in use to the contact blocks P in the upper row, and
whose negative poles are when in use connected with the contact
blocks N in the upper and lower rows. The connection of the
working places, 1 to 3, to the cells is effected by contact plugs.
If one wished to work at place 1 and required 4 volts, a plug
should be put in the upper row between P and 1 of the first set,
and a second between N and P of the following group in the
under row. In this manner the place 1 receives its current from
the cells A and B in series. If, now, place 2 requires this same
tension, but double the current strength for its investigation, the
cells C, D, E, F are connected two and two in parallel and the
two groups in series as follows : above, in groups 3 and 5, plugs
are inserted between P and 2; below, in groups 4 and 6, between
N and 2; and finally above (for series connection), in groups 4
and 6, between N and P. It is clear that with this arrangement
many mistakes will be made by the student which will damage
the battery by short-circuiting. For a larger number of working
places than three the confusion will became worse, quite aside
from the fact that the integrity of the many contact surfaces will
be injured by acid vapors.

In charging, all the cells are connected in series and during the
night placed in series with a bank of lamps directly in a no volt
lighting circuit. For the regulation and measurement of the elec-
trical energy, portable resistances and measuring instruments
were supplied to the working places.

The inadequacy of this equipment was soon recognized, and
in time as the number of students in electrochemistry became
larger, it was replaced by a new outfit. This contains 16 working
places in a room having 40 square metres of floor space. As a
source of current two rows of 24 accumulator cells were used

ELECTROLYTIC IABORATORIES

they having a normal discharge rate of 15 amperes (maximum
30 amperes) and a capacity of 120 ampere-hours.

The new scheme of connections is shown in Fig. 25. Each
working place has a battery controller, shown to the left in the
figure; all the controllers being mounted upon 2 enameled slate

UNIVERSITY OF PENNSYLVANIA 41

switch-boards at the head of the room. Each of these consists
of a contact circle of 24 knobs, each knob in connection with a
cell of the corresponding row of the battery, over which revolves
two arms insulated from each other. These lead off the current
at the desired tension to the working places indicated at the right
of the figure. In these conductors for protection against over-
loading — also on the switch-board — are double-pole fuses and a
double-pole switch to cut out the concerned working place, all
plainly seen in the figure. Each work table is provided with a semi-
circular current regulator, a voltmeter and two ammeters. The
first has a total resistance of 172 ohms with steps in geometric
ratio. The voltmeter has a measuring limit of o to 50 volts di-
vided to 0.5 volts, the ammeter, o to 1 ampere divided into 0.01
ampere and the other, o to 25 amperes divided into 0.2 ampere.
Accordingly as the student wishes to use small or large currents
he connects his bath between + and 1, or + and 25. The meas-
uring instruments are fixed in a permanently closed glass case for
protection from fumes, so that the only exposed apparatus in the
laboratory are the controllers, the regulators and the terminals.

Besides the two switch-boards spoken of, there is still a third
for four extra places so arranged that one can work with the full
tension of all the whole 2 X 24 cells, or 96 volts. A parallel ar-
rangement of the batteries is not provided since the maximum
discharge current, about 30 amperes, suffices for the regular work
of the student.

Central Laboratory of the Stock Company of Stolberg
and Westphalia at Stolberg, Rhenish Prussia.

The three plants at Hoboken, Luttich and Konigsberg, and sev-
eral others not mentioned here, sprung from the electrolytic plant
in my laboratory, which was first erected in its primitive form in
1883 and remodelled in 1892 and 1899. These reconstructions
were erected under my direction, by the Raacke Brothers, of
Aachen, upon the basis of my accumulated experience, the fol-
lowing form having been in use since 1889.

The local arrangement of the apparatus board, the electrolysing
tables and the accumulator battery are shown in Figs. 26 and 27.
It is particularly worthy of notice that the accumulators are

ELECTROLYTIC LABORATORIES

placed in a communicating room so that, in charging, the acid
fumes set free can be removed without vitiating" the air in the
laboratory. The battery is accessible through glass doors into the
communicating room. The apparatus board is let into a recess
at the end wall of the electrolytic laboratory. By this arrange-
ment floor space is saved, and, for protection from the laboratory
fumes, it is encased by sliding windows; and, finally, the leading
in and connecting wires to the instruments are easily accessible

Fig. 26.

at all times without disturbing their operation. This last condi-
tion is advantageous where unusual work is frequently done,
which requires unusual arrangements of the connections.

IABORATORY AT STOLBERG

ELECTROLYTIC LABORATORIES

The construction of the analytical work table is well adapted to
its purpose. The characteristic of the same is the shelf-like ar-
rangement of the two table tops, the upper one 20 centimetres
above the lower, so that the electrolytes can be emptied out of the
vessels right on the spot by means of a simple siphon.

As a source of current the plant uses :

■0

qrc

Ijikt*

<$ma// /toaom*

jfutomtu

cut-out

z r_ J9*t/er*f

mmeAsr

fimrre-

jfoin-c*rre*t

Cfar$tn£ Ran.

Fig. 28.

i. A shunt wound dynamo rated at 60 amperes at 12 volts. This
is directly coupled to a small high speed steam engine made by
Daevel of Kiel, and has a current regulator and voltmeter ar-
ranged close by the machine. Because of the arrangement of the
steam pipes at the time, the engine was unfortunately placed some
60 metres from the laboratory. The current was led over through
a bare copper cable of 100 square millimetres cross-section which

LABORATORY AT STOI3ERG 45

was strung on porcelain insulators. This machine installed in
1892, is, however, because of the great distance at which it was
placed and the troublesome service thus involved, only used as an
auxiliary.

Boner

&ar/ertf

H I J Hj H r\ r

+1/c/t

x &cuhie Current

ffrerg/J.

flfofc -

TfieSfimt.

<5i7i£/e Current &ren£Mi*

JD/scharJm£ PM*

Fig. 29.

2. In the year 1897 a 5° horse-power engine and dynamo for
lighting of the zinc works, the work rooms and the rolling mill
was put into service and this furnished current the whole night.

46 ELECTROLYTIC LABORATORIES

The lighting plant was run at no volts, which is naturally too
high for the charging of accumulators. The reduction of the
voltage was accomplished in a simple manner; six of the 600
candle-power arc lamps of this plant were used as resistance and
their current led to the battery for charging by means of a com-
mon conductor. If no charging was going on the place of the
battery was taken by a corresponding resistance thrown into the
lamp circuit by means of a double-pole charging switch. The
arrangement of the connections is shown in Fig. 28. The arc
lamps are connected in pairs in series absorbing each 90 volts, and
the remaining 20 volts of the 1 10 volt plant is in general carried
by the resistance, or in other words uselessly converted into heat,
and so its use for charging the battery costs practically nothing.
By the use of only six lamps in the above manner the battery was
not overloaded during a night. The battery, discharged during
the day, was charged at night so as to be ready the next morning.
3. As the secondary source of current there was used the pre-
viously mentioned accumulator battery consisting of four — two
pairs in series — cells of the Cologne Accumulator Works of Gott-
fried Hagen, of Kalk, near Cologne, with a capacity of

252 ampere-hours with 25 amperes discharge rate in 10 hours,
224 " " " 32 " " " " 7, "

2j " " " 4.2 " " " " 5 "

t.Q << <« << £q «« it (i << ~ <<

From the battery four wires lead to the double-pole discharge
switch on the apparatus board by means of which the two pairs of
cells can be connected in series or parallel, and so obtain a double
current at 4 volts, or a single current strength at 8 volts, the nor-
mal discharge rate. During the charging the cells are connected
in series. The scheme of these connections is clearly shown in
Fig. 29.

We now come to the real apparatus equipment itself: its ex-
terior is shown in Fig. 30 and a scheme of the connections in de-
tail in Fig. 31, which will be described later.

The apparatus has to perform the functions of distributing and
regulating the electrical energy as follows :

(a) charging the accumulators by the small dynamo,

(b) charging the accumulators by the large dynamo,

LABORATORY AT STOLBERC

ELECTROLYTIC LABORATORIES

LABORATORY AT STOLBERG 49

The apparatus for a and b and their functions have already
been explained, and it now remains to be said that the current
from the small dynamo can be regulated from the laboratory by
the dynamo regulator G, and its current can be read off upon the
large ammeter up to 60 amperes ; and that, further, an automatic
minimum current switch protects the dynamo from reverse cur-
rents of the battery. Direct dynamo currents can be taken from
the terminals B and C, eliminating the battery from the circuit.
In designing the plant for the purpose named under (c) it was
kept in mind that not only the current strength and tension of
each single bath must be measured, but also that of all ; and that
in many cases it is desirable to be able to alter the direction of the
current in the baths without changing other conditions.

For measuring the voltage there is used a Hartmann & Braun
voltmeter with scale divided from o to 12 volts, connected to a
double-pole voltmeter switch with 10 contacts ; the contacts 1 to 8
being used to measure the voltage at the eight baths, 9 the volt-
ge of charging or discharging the battery and 10 the voltage of
the small dynamo. The total charging or discharging current is
measured by a large ammeter divided from 10 to 60 amperes, or,
in case it is under 10 amperes, upon the instrument reading from
o to 10 amperes in series with the first. In* this case the switch
D on a shunt with the latter instrument is opened, and in the other
case, when the current is above 10 amperes, it is closed. In order
to measure the current consumption in each single bath without
the use of as many ammeters as baths the switch E is provided.
It is a double-pole fork switch without interruption of the current.
If this stands in the position as shown in Fig. 31 then no current
will flow through the smallest ammeter of o to 3 amperes, but
rather it flows through the 10 ampere instrument to the baths. If
it is wished on the contrary to measure the current used in one
bath then the corresponding switch lever is placed upon the free
contact, Fig. 32, and the bath current in question is forced to pass
through the small ammeter.

For regulating the energy supplied to the baths there is in each
circuit an adjustable resistance with 21 steps. After leaving this,
the current has to pass through the double-pole reversing switch
F, and finally to the baths.

ELECTROLYTIC LABORATORIES

In order not to complicate the drawing unnecessarily in Fig. 31
the connection of the current with only two baths is completely
shown, and for the same reason the connections to the voltmeter
are omitted, this being clear without further explanation.

7 Cu^our

Sur/tcA.

W/Acut

breakim

ecxnecf/oTis.

To M *e Sa//rs

Measurement of the current Strength

Pig. 32 .

After a two years use of my laboratory and continuous obser-
vations in other laboratories, I have noted a number of desirable
improvements — improvements which for the most part will cheap-
en the operation, simplify the manipulations and increase the ac-
curacv of the results.

THE ELECTROCHEMICAL LABORATORY OF THE MASSACHU-
SETTS INSTITUTE OF TECHNOLOGY.

BY PROF. H. M. GOODWIN.

During the past year the Institute has equipped a special labo-
ratory for instruction in electrochemistry to meet the demand
which the many rapidly growing industries in this branch of ap-
plied science have created for men especially trained to undertake
the class of problems arising in connection with the development
of such industries. As frequent inquiries for a description of the
arrangements and equipment of the laboratory have been received
during the past winter, it is believed that it may be of some inter-
est and value to those who may be contemplating a similar labo-
ratory equipment to describe briefly the essential features of the
arrangements which have been worked out.

The electrochemical laboratory consists of two parts, one de-
voted to what may be called electrochemical measurements, and
to processes requiring currents not greater than about fifteen am-
peres, and the other to technical work requiring heavy direct or
alternating currents up to several thousand amperes. In addition
to these two pricipal rooms, six other special rooms equipped for
measurements of electrical conductivity, dielectric constants, phy-
sico-chemical quantities, and for research, are provided. These
contain no essentially novel features in their equipment, and re-
quire, therefore, no special description.

The laboratory of electrochemical measurements (30x62 feet),
is equipped with desks for twelve students. The general arrange-
ments are indicited in the accompanying plan, Fig. 1, Room I.
The most important feature of the equipment in this laboratory is
the arrangements of circuits and other conveniences on the desks.
These are arranged in three groups of four each with a sink at
each end and a large thermostat in the center. Each desk is pro-
vided with three faucets, including a Richards suction pump and
gas at the sink end. Along the back of each desk is a switch-
board, 14 inches high, to which the terminals of the various cir-

ELECTROLYTIC LABORATORIES

cuits are brought. Opposite switchboards are separated by a 4-
inch space and bridged over the top by a shelf. This permits am-
ple space at the back of each switchboard for the necessary wir-
ing.

FIG. 33.— LABORATORY OF ELECTROCHEMICAL MEASUREMENTS.

A — Private Office.

B — Balance Room.

C— Hot Closet.

D — Group of four Students 1 Desks.

D' — Instructor's Private Research
Desk.

E — Three Hoods for Electrochemical
Analysis.

F — Electric Furnaces.

G — 25-kw. Direct-current Motor Gen-
erator.

H— Hood.

I — Instrument Case.

K — Set of ten large Storage Batteries

and Switchboard.
L— 18-inch Shelf.

M — Grinding and Polishing Machine.
N — 2-h. p. Power Motor.
O — 50-kw. Transformer.
P — Slate-top Masonry Pier.
R — Reagent Shelves.
S— Sink.
T— Thermostat.
V — Steam Evaporating Cups.
W — Special Still for Conductivity

Water.

The circuits provided are four in number, no volts, I2j4
volts, 25 volts, and 2 volts, respectively. The first is wired from
one side of the general 220-volt direct-current power circuit of
the building; the second and third constitute a three-wire system
from a special motor generator located at G, Fig. 33 ; the 2-volt
circuit is connected to a large storage cell, four of which, one for
each desk are set up between the desks and under the thermostat.
The method of wiring is shown in Fig. 36.

The battery circuits are brought up back of the switchboards
as indicated by the dotted lines B. The three-wire I2y 2 and 25-
volt circuit is wired along the top of the switchboard on one side
of the desks, and tapped off across to the opposite side as indi-
cated. The three-wire no-volt and 220-volt circuit is run in a
similar manner along the top of the opposite switchboard, and 1 10
volts tapped off at each desk and across to the proper cut-out on
the opposite desk. The circuits are brought out to General Elec-

MASSACHUSETTS INST. OF TECHNOUXJY

trie porcelain combination switch and cut-outs, connected in turn

S tKQj y

m^&

©- CO-oG'

Zv>

DO CO

D3 CO

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i

r 1 '

lll
in!

IH|:::.v:

i;sss

"HOT

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M

w
p

to
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CO
to

o
o
6

S *

v « 5

5 8 « rt

3 5 *?2 •**

o*£ g £

*j rt C w

3 ^ « -

U^H §

v©
CO

a ri

8-3 S
9 2 ~

s
cy

S
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w
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W
u

■♦-•

to '

a
3
o
o
cd

3
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to ^

M W «

to large double binding posts mounted on fiber. Each circuit is

56 ELECTROLYTIC LABORATORIES

fused in general for 10 amperes. Currents of this magnitude may
be taken from any circuit without affecting adjacent circuits. The
fuse plugs in each circuit may be replaced by lamps of different
resistances, a set of which permits a convenient and ready adjust-
ment of current within wide limits. For a finer adjustment of
current a large rheostat on the floor at the end of each desk, wired
to terminals R, on the switchboard, is provided. For a still finer
adjustment of resistance, such as is required in tapping off poten-
tials in determining decomposition voltages, a German silver wire,
or coil with sliding contact is stretched between binding posts
along the top of the switchboard. The electrical accessories of the
desks are completed by portable Weston ammeters. and voltmeters.
The general arrangement may be seen in Fig. 35, which gives a
general view of the laboratory looking south.

The porcelain lined thermostat, 36 x 18 x 20 inches, in the cen-
ter of each group of four desks, is heated and regulated electric-
ally. The outside is heavily lagged with magnesia to reduce ra-
diation. To bring the temperature quickly up to any desired value,
a heating coil of heavy German silver wire is switched onto the
no volt circuit at C, Fig. 36. A constant temperature is then
maintained by an ether regulator which operates a relay mounted
at the left of the open space above the thermostat. As the tem-
perature of the bath rises or falls above the desired temperature,
the relay opens or closes alio volt circuit through a 32-c. p. lamp,
the bulb of which is nearly completely immersed in the water of
the thermostat. The heat thus generated is more than sufficient
to compensate for the loss by radiation and evaporation, and has
been found to work most satisfactorily. A small no-volt 1-12
horse-power motor serves to drive in the thermostat a shaft with
paddle wheels for stirring the water, and with a device for ro-
tating bottles for saturating solutions. The motor is also belted
up to a shaft which runs the whole length of the shelf at the top
of the switchboard. The shaft carries four cones of pulleys, one
for each desk, by means of which power is furnished to each stu-
dent for stirring. A heavy brass rod carrying an adjustable arm
with a horizontal cone of pulleys equal in size to those on the
shaft, can be screwed, when desired, into a brass plate into the
top of the desk.

MASSACHUSETTS INST. OF TECHNOLOGY 57

The equipment of electrochemical apparatus provided with each
desk is shown in Fig. 34. It consists of a silver, a copper, a gas
and a titration voltameter, transference apparatus, complete con-
ductivity apparatus with a resistance box and a slide wire bridge,
a Lippmann electrometer, keys, commutators, a potential box and
complete accessories for potential work, a three-scale, 3-volt, 15-
volt, and 150-volt Weston voltmeter, and a Weston milli-volt-
meter, with 15-ampere auxiliary shunt for use as ammeter. The
advantage of giving each student a complete outfit at the start is
evident ; for first, it permits the whole class to work concurrently
on the subjects which are being discussed in the lectures; second,
it is conducive to great economy of time in the work of the stu-
dent, and third, it greatly increases the interest and care with

which the student undertakes the calibration and standardization
of his instruments, if he feels his own responsibility for them
throughout all his later work.

The laboratory is provided with a balance room, a hood, a dry-
ing closet, steam cups, distilled water, and a large still of special
construction for the redistillation of pure water for conductivity

ELECTROLYTIC LABORATORIES

work. Three hoods of special construction, each equipped with
four different circuits of constant voltage connected with the
large accumulators, and with means of regulating and varying
their temperature, are provided for electrochemical analysis.

The laboratory for heavy current work, Room II. (30 x 32
feet), is equipped for the purpose of illustrating on a fairly large

MASSACHUSETTS INST. OF TECHNOIX)GY 59

scale various electrochemical processes involving the use of both
direct and alternating currents, and to provide facilities for re-
search work along these lines.

Direct current is supplied from a Holtzer-Cabot motor gen-
erator of 25-kw. capacity, shown in Fig. 37. It is enclosed in a
room with glass windows to protect it from dust and acid fumes.
The motor is supplied with power from the electrical engineering
power plant at 220 volts direct current. The double current gen-
erator is directly coupled to the motor and delivers under full
load 1000 amperes at I2y 2 volts at each commutator, which may
be connected either in series or parallel as desired. The voltage
may be varied at will by varying the resistance of the separately
excited fields. The generator may be switched onto the three-
wire system leading directly to the switchboard at the front of
each desk as already described, or to heavy copper bus-bars 2
inches x y 2 inch section and 32 feet in length which extend
around two sides of the laboratory, 5 feet above the floor. Con-
nection is made between the electric furnaces, which are ar-
ranged along the sides of the room and the bus-bars by means of
heavy flexible cables which are easily clamped to the latter by
heavy screws. The general arrangement is shown in Fig. 38.

For electrolytic work requiring very constant low voltage, and
in particular for work which must proceed continuously over
night, such as plating, electro-analysis and electro-depositions in
general, a set of ten large chloride accumulators capable of fur-
nishing 150 amperes each are provided. These are each connect-
ed to a switchboard bv means of which anv combination of the
cells in series and parallel may be easily effected. Currents from
150 amperes at about 20 volts to 1500 amperes at 2 volts are thus
available independent of the motor generator. The batteries are
charged in series on the 25-volt circuit from the generator.

For furnace work requiring heat only, and for the purpose of
bringing to a state of fusion electrolytes to be subsequently sub-
jected to electrolysis, a 50-kw. transformer of special construction
is provided. This is of the core type, and can be used on either
a 2200 or 1 100 volt circuit at 60 or 125 cycles, by connecting the
primary windings in series or parallel. At present it is used on a
1 100- volt circuit of 125 cycles. There are 16 independent sec-

60 ELECTROLYTIC LABORATORIES

ondaries so wound that each can deliver 300 amperes at 10 volts.
The terminals of each of these are brought out to a swtchboard
where they can be thrown in multiple or series or used in inde-
pendent combination as desired. The two halves of the switch-
board are quite independent, so that 25 kilowatts can be drawn
simultaneously from each set of bus-bars at any voltage from 10
to 80 volts in steps of ten volts. By connecting the two halves in
series of parallel, currents from 300 to 4800 amperes at pressure
from 160 to 10 volts resepctively can be obtained.

FIG. 39.— 50 KW. TRANSFORMER SWITCHBOARD AND RESISTANCE

Flexible cables, each capable of carrying 500-700 amperes are
used to connect the transformer with furnaces which cannot be
built or brought close to the transformer. Fig. 39 shows the trans-
former connected for a run on a resistance furnace used in an in-
vestigation now being carried out on the properties of refactory
oxides. The laboratory is provided with all the necessary acces-
sories to the above power equipment in the way of resistances,
choke coils, and direct and alternating current measuring instru-
ments for the measurement of current, voltage and power. The
calibration of these instruments and of the student's own desk in-
struments form a part of the regular work which each student
performs in the electrical standardizing laboratory. For meas-
uring high temperatures, the laboratory is well provided with

MASSACHUSETTS INST. OF TECHNOLOGY 6 1

thermo-electric pyrometers. The calibration of these instruments
forms a part of the regular work in the laboratory of heat meas-
urements.

The laboratory is equipped with six different types of furnaces,
including the Moissan and Borchers type, platinum and graphite
resistance furnaces, and a large furnace especially constructed for
aluminium reduction. As many furnaces have to be built up for
each run, special tables have been designed for this purpose.
These contain no wood in their construction except the supports.
The tops are concrete arches supported at the sides by iron I-
beams. A layer of fire bricks is placed in sand on the cement,
and on this foundation the furnaces are built. No danger from
fire has been experienced thus far with tables of this construc-
tion.

Finally should be mentioned the typical electro-plating plant
with tanks of various size up to 30 gallons capacity for illustrating
nickel, copper, silver, gold and brass plating. This includes, of
course, the necessary grinding, polishing and finishing acces-
sories.

In concluding the above description of the laboratory which
has been equipped to provide special facilities for instruction in
electrochemistry, it may not be out of place to indicate the general
plan of the course in electrochemistry as given at the Institute.
The present four years' course was established by the faculty five
years ago, and is given under the direction of the department of
physics, that department having inaugurated special instruction
in electrochemistry as early as 1894. The chief features of this
course are very thorough training in theoretical and applied elec-
tricity and chemistry, together with as much of the subjects of
mechanical engineering and metallurgy as can be included in a
course of four years' duration.

The work of the first vear is common with that of all other en-
gineering courses, and includes mathematics through analytic
geometry, mechanical drawing and descriptive geometry, chem-
istry, language and general culture studies. The latter are con-
tinued in all courses, at the Institute throughout the first three
years. Specification begins in the second year in chemistry and
electricity. The former consists of qualitative and quantitative

62 ELECTROLYTIC LABORATORIES

analysis throughout the second year and first half of the third
year, followed by organic chemistry, gas analysis and assaying
in the second term of the third year. These courses all lead up
to a very thorough course in industrial chemistry given through-
out the fourth year.

Theoretical chemistry is begun in the second year and is con-
tinued to the end of the third year. This forms a very thorough
preparation for the theoretical and applied electrochemistry,
which constitutes a large part of the professional work of the
fourth year.

The electrical studies are also arranged in a progressive se-
quence. Electricity is treated first in the course on general phy-
sics of the second year. Theoretical electricity is then begun in
the second term of this year, and is continued through the
third and fourth years, the later work being devoted to the
subject of periodic currents and their applications to alternating
current machinery. Parallel with this theoretical work courses
are given in electrical measurements and testing, in electrical en-
gineering and in the electrical engineering laboratory.

In addition to subjects included in the two lines of work de-
scribed above, a certain number of engineering subjects are re-
quired. These include metal work, mechanical engineering, draw-
ing, mechanism, valve gears and thermodynamics, all leading up
to a very practical course in the fourth year on general machinery,
including engines, pumps, compressors, etc. Non-ferrous metal-
lurgy, and work in the metallurgical laboratory complete the
group of subjects included.

In the last term of the course each student devotes a consider-
able portion of his time to the preparation of a thesis, embodying
the results of an experimental research on some electrochemical
subject.

Four years is admittedly too short a time to include in a course
all subjects which an electrochemist is likely to find useful in the
practice of his profession, and a fifth year, or a graduate course
which can be arranged to great advantage, is highly recommended
to those who find it practicable to devote another year to study be-
fore beginning professional work.

LABORATORY OF APPLIED ELECTROCHEMISTRY

University of Wisconsin.
BY PROF. CHARLES F. BURGESS.

The work in applied electrochemistry is under the direction of
Prof. C. F. Burgess, assisted by Mr. Carl Hambuechen and Mr.
J. G. Zimmerman. The laboratory occupies the second floor of
the electrical laboratories, the plan being shown in the accompany-

■ — rf,_— — ■ — ■ f^' H ~^-rr l = =|- -^

FIG. 40.— APPLIED ELECTROCHEMISTRY LABORATORY.

A. Lecture Room, with projection lantern. B. Workshop. C Office and Analytical
Room. D. Electrodepositing Room. 1. Storage Batteries. 2. Electrolytic Vats. 3. Clean-
ing Tanks. 4. Motor-Generator. 5. Switchboard. 6. Centrifugal Separator. 7. Rotary
Ball Mill. 8. Compressed Air Receiver. E. Grinding and Polishing Room. P. Drying
Room. G. Store Room. H. General Electrolytic Laboratory. 1. General Switchboard.
2. Work Tables. 3. Hood. 4. Reagent Stand. 5-6. Instrument Cases. 7. Filter Press.
8. Electrolytic Bench. I. Electric Furnace Room. J. Storage Battery Room. K, L, M.
Research Rooms. N. General Laboratory.

ing drawing. The portion of the floor which includes the re-
search rooms is at present in process of construction, and will
practically double the space available for electrochemical work.

64 ELECTROLYTIC LABORATORIES

The present space includes a large plating room, rooms for
polishing and grinding, chemical analysis and weighing, work
shop, drying room, general laboratory, high-tension room, re-
search laboratories, a storage battery room, and store rooms, one
of which is not shown on the plan. On the first floor adjoining
the dynamo room is the electric furnace laboratory.

The plating room equipment comprises a motor-generator hav-
ing a capacity of 300 amperes at a pressure up to 10 volts on the
low pressure side ; twelve large lead lined, and wood and enamel
lined tanks of a capacity of from 30 to 60 gallons capacity, hot
water, lye and cleaning tanks. Plating and refining solutions for
copper, nickel and zinc are maintained continually, and the other
tanks are used for experimental work on various other solutions.
A rheostat is connected to each tank, and voltmeters and ampere
meters are installed so that by a simple switching arrangement
they may be connected to any of the tank terminals. The equip-
ment in the electrodepositing department was obtained chiefly
from the Hanson & Van Wir^de Co., and is similar to that in-
stalled by them in technical plants.

The grinding and polishing room contains two high-speed
lathes, driven by an electric motor. By means of the above equip-
ment instruction is given in electroplating, electrotyping, and the
refining and recovery of metals.

The equipment of the general laboratory includes eight spec-
ially designed switchboards for varying and regulating the cur-
rent used in small electrolytic experiments, together with a large
number of rheostats, electrolytic tanks, stirring devices, instru-
ments for measuring current, e. m. f . and resistance. A consider-
able proportion of the apparatus has been designed and construct-
ed in the laboratory, and to the valuable assistance of the Mechan-
ism department of the College of Engineering, in charge of Mr.
E. H. J. Lorenz, many of the special instruments and devices are
due. The equipment also includes balances, filter presses, centri-
fugal drying machine, a rotary ball mill and other grinding mills,
a vacuum drying oven, etc. A system of compressed aif fur-
nishes at various outlets around the laboratory air at a pressure
of 60 pounds to the square inch.

— 30-KW. TRANSFORMEH FOR KI.KCVRfC FCHNACKS.

66 ELECTROLYTIC LABORATORIES

Electrical energy is furnished by the dynamo laboratory and by
the city lighting and power circuits. Both alternating and direct
currents are available, the former in quantities up to several hun-
dred amperes at a pressure of 1 10 volts, and the latter up to iooo
amperes at the same pressure. By means of a 20-kw. high-ten-
sion transformer (Fig. 41) pressures are available up to 60,000
volts.

In the electric furnace room is a switchboard connected
to a Bullock direct-current generator, capable of delivering

1000 amperes at a pressure of no volts. This current is
regulated and controlled for furnace work by a water-pipe
rheostat illustrated in accompanying photograph (Fig. 42). It
consists of ten lengths of j4-inch wrought iron pipe
capable of carrying about 250 amperes without excessive
heating with no water circulating, and a maximum ca-
pacity considerably above 1000 amperes with the water

UNIVERSITY OF WISCONSIN 67

turned on. The current is regulated in ten steps by opening or
closing the switches, which short-circuit the various sections as
may be required. A self-acting switch protects the generator and
engine from damage by sudden short-circuits. Water is supplied

to each of the lengths of pipe through a two-foot length of rub-
ber hose, such material being necessary to prevent short circuits
between the consecutive lengths of pipe.

A 10 kw. auxiliary rheostat made by the Wirt Electric Co., of
Philadelphia, consisting of cast-iron strips supported on an iron

68 ELECTROLYTIC LABORATORIES

frame and mounted on rollers serves for handling currents below
150 amperes.

Alternating current for high temperature work is obtained
from alternators in the electrical laboratory and from the city
power circuit and is at present available in quantities up to 40 kw.,
although a 200 kw. alternator is to be installed, and in operation
within a few months. For adapting the alternating pressures to
the various uses required in furnace work a 20 kw. transformer
was especially designed for this purpose and constructed in the
laboratory. By means of switching arrangements it may receive
its full capacity at pressures ranging from no to 220 volts, and
the switches which connect the subdivided secondaries in series

or parallel pressures from 15 to 200 volts may be delivered to the
furnaces. A high-pressure coil, capable of delivering 20 amperes

UNIVERSITY OF WISCONSIN 69

at 1000 volts is used for operating high resistance electric fur-
naces where the material under treatment is a high resistance sub-
stance such as molten silica.

Various small electric furnaces of the Moissan and Borchers
types which have been imported are installed and used for various
high temperature small scale experiments. Most of the furnaces
used have been, however, constructed in the laboratory, various
refractory materials, such as magnesite and silica fire-bricks, mag-
nesia, lime, silica, etc., being employed in such construction.

To adapt the electrode supports to the construction of various
types of furnaces necessary for a variety of experimental work,
two sets of electrode supports have been designed and constructed,
and which has given excellent satisfaction. (Fig. 43). These
are capable of holding carbon or graphite rods up to 2 inches in
diameter, and have a capacity for handling currents up to 1000
amperes, the terminal blocks being provided with water-cooling
pipes. The horizontal type is capable of vertical adjust-
ment by means of a slot and lock-nut and the electrodes
may be set at any desired angle through 90 . (Fig.
44). The electrodes are adjustable backward and for-
ward by means of lever arms. The vertical electrode sup-
ports are an adaptation in part of the vertical type suggested by
Mr. R. S. Hutton, of Owens College, Manchester, England.

The work tables of the furnace room are constructed of wood
frames supporting a top of concrete and cement three inches thick.
This form of top was adopted to reduce danger from fire, but
experience has shown that in an experimental room of this sort
the entire absence of wood work is desirable.

For conducting high temperature and electrolytic work various
new forms of apparatus and methods have been devised, some of
which are referred to in the following paragraphs.

In measuring single electrolytic potentials the well known
"calomel" electrode is employed, its e. m. f. being assumed as
0.56 volt, and where convenience and rapidity requires the use of
cadmium or other suitable metal, the single values of such are de-
termined in terms of the "calomel" standard.

For measuring small electric potentials with a high degree of
accuracy a Leeds potentiometer is available, but for ordinary pur-

JO ELECTROLYTIC LABORATORIES

poses where a decree of accuracy consistent with unavoidable ex-
perimental error is attained, a simpler and much cheaper potentio-
meter outfit has been designed and constructed in the laboratory
which permits an accuracy within one-tenth of one per cent. Two
forms of this potentiomoter outfit are used. The appara-
tus was constructed in the laboratory. It consists of iooo ohms
subdivided into ten io-ohm coils in series, with nine 100-ohm
coils, each of these steps being connected to suitable contact
terminals to which radical arms make contact. This is an adapta-
tion of the Ostwald potentiometer, with radial adjustment arms
which increase the convenience of working, and in addition there
is supplied a 9000-ohm coil, which can be placed in series with the
1000 ohms, increasing the range of measurement ten times. By

fig. 45.
means of this outfit, potentials varying from less than 0.001 volt
to over 100 volts can be measured with an accuracy of one-tenth
of one per cent. It is used for the calibration of ampere meters
and voltmeters, the measurement of c. m. f, s., and resistance by
the fall of potential method. It has proved especially suited to
the determination of resistances of very high value, above 100,000

UNIVERSITY OF WISCONSIN

megohms, such as are encountered in the determination of insu-
lation resistances.

The indicating instrument used in connection with this poten-
tiometer is, for ordinary purposes, a horizontal portable galvano-
meter or milli voltmeter, but where these cannot be used satis-
factorily, a portable capillary electrometer is employed. The
form of electrometer which has been found especially adaptable
is a modification of the well-known Lippmann instrument, and is
illustrated in Fig. 45. It is so arranged that there is no possible
ity of spilling the electrolyte. The position of the meniscus is de-
termined by means of a small microscope fitted with a micrometer
eye-piece, and the portability of the instrument and the freedom
from vibration influences may be judged from the fact that the
meniscus may be adjusted upon the scale of the eye-piece and
after shipment by express may be found ready for immediate use
without readjustment. A portable instrument of this sort was
constructed with a sensitiveness of 0.00002 volt, and used for sev-
eral months in a study of the changes of e. m. f. which are set up
by iron under various conditions of strain.

FIG. 46. MEASURING RESISTANCES.

For the measurment of electrolyte resistances the well-known
methods are employed. A method which has been found of great
convenience, overcoming the various sources of error in a degree
sufficient to meet commercial requirements is illustrated in Fig.
46, where an ordinary voltmeter is the only indicating instrument
employed. The method of operation consists in placing the elec-
trolytic resistance in a rectangular trough of such length as to fur-
nish between the terminal electrodes a resistance having a suitable
proportion to the resistance of the voltmeter. The measurement
consists in connecting the cell terminals in series with the volt-

72 ELECTROLYTIC LABORATORIES

meter to a ioo-volt or other convenient source of pressure. By
closing the switch S to a the voltmeter gives the total pressure
E, and upon opening the switch the resistance of the electrolyte is
thrown in series with the voltmeter, thereby reducing the reading
to the value E'. By applying the following formula the resistance
of the electrolyte R' is derived, R being the resistance of the volt-
meter.

™ „E-E'

This method is especially applicable for the rapid determination
of the resistances of the earth, or any high resistance electrolytic
conducting material.

Where is becomes desirable to measure the specific resistance
of an electrolyte by simply immersing the measuring apparatus
in the solution, as a hydrometer would be used for determining

FIG. 47. — MEASURING SPECIFIC RESISTANCE.

the density, a tube containing the electrodes, as illustrated in Fig.
47, is employed. The measurement can be made by means of a
voltmeter, as previously described, or by other suitable means.

An important part of the equipment of an electrochemical labo-
ratory consists in rheostats for adjustment of current values.
Some rheostats which have been designed and constructed to meet
the special requirements of this laboratory are in frequent
use. To obtain a small step-by-step adjustment of cur-
rent for electrolytic work from a no- volt source of supply,

UNIVERSITY OP WISCONSIN

six wall lamp resistance boards are installed. These permit of
range of current from 0.1 ampere to 6 amperes in fifty steps, each
board being supplied with an ammeter and voltmeter.

FIG. 48.

Carbon rods mounted on an iron frame and protected by
an iron screen constitute a cheap and satisfactory form of
rheostat for large volume, low pressure currents. A spe-
cial form of rheostat for use in the testing of one or
two storage cells is also shown. ( Fig. 48) . It is a
combination of switch and rheostat, the side bearing springs
being divided into a number of sections faced with carbon blocks
about ^4-inch thick. The blade of the switch consists of a metal
frame holding strips of carbon, and the two opposite sides of the
switch constitute the terminals of the resistance. The resistance

74 ELECTROLYTIC LABORATORIES

is adjusted by the sliding contact to the exact value desired, this
being done by closing the knife of the switch to the desired de-
gree. This form of switch has the advantages of cheapness, grad-
ual adjustment, and large current-carrying capacity.

In an electroplating room one of the difficulties with rheostats
commonly used is the corroding of the contacts which therefore
require frequent attention. The wall rheostats illustrated in the
photograph from the electrolytic depositing room were designed
to overcome this difficulty by enclosing the contact points behind
a glass cover. These rheostats have now been in use for five years
without giving the least trouble from poor contacts.

A high pressure rheostat of low current carrying capacity, and
having a sliding contact adjustment, is made by cutting a circular
band in a slate or stone slab and filling this with a mixture of
graphite, pumice-stone and a binding material, the relative pro-
portion of the material being determined by the degree of resist-
ance and current carrying capacity required. A considerable num-
ber of such rheostats are in use and are found to be durable and
cheap, and capable of being heated to about 150 C.

The work of the first semester in the applied electrochemistry
laboratory consists in performing such experiments as will give
an idea of the various methods of making electrolytic measure-
ments of resistance and potentials, of the oxidation and reduction
and other electrolytic effects of the current; experiments illus-
trating the applicability of Faraday's law to the deposition of
metals and production of various chemical reactions. The var-
ious details connected with the deposition of nickel, copper and
zinc and other metals for plating purposes are studied together
with the methods of cleaning and preparing the surfaces both be-
fore and after receiving the deposits. The effect of current
density, temperature, composition, density and circulation of the
electrolyte as regards the influence on the character of the metal
deposit are illustrated by a set of experiments. Batteries, both pri-
mary and secondary, are subjected to tests of efficiency, resist-
ance, polarization, etc.

The work during the second semester deals with the operation
and study on a miniature scale of various technical applications of
electrolysis and high temperature work. This includes the pro-

UNIVERSITY OF WISCONSIN 75

duction of hypochlorites, chlorates by the electrolysis of salt solu-
tions ; also the production of alkali, chlorine, pigments, metallic
sodium, calcium carbide, carborundum, (Fig. 49), silicon, graph-
ite, aluminium, magnesium, and various other materials of a simi-
lar kind.

The thesis work and the graduate study in applied electrochem-

SIG. 49.

istry covers largely the study of special problems. While it con-
sists mostly in laboratory investigation it includes also an exam-
ination of the literature bearing on the subject, facilities for which
are available in the University and State Historical library, one
of the most complete libraries in the country, having complete
files of most of the important scientific and engineering publica-
tions in English, German and French, together with complete sets
of the United States, British and Canadian patents.

Among the investigations which are now under way are the fol-
lowing. A study of the electrolytic refining of iron has been in
progress for over two years, and with results which indicate that
chemically pure iron can be produced as simply and as cheaply
as is the case with copper. About one-half ton of this iron has
been deposited, chemical analyses of which show no trace of car-

y6 ELECTROLYTIC LABORATORIES

bon, manganese, silicon and other impurities commonly found in
iron.

A study of the electrolytic rectification of the alternating; cur-
rent, utilizing the well-known property of aluminium and other

metals for this purpose, has resulted in the development of several
types of electrolytic rectifiers to fulfill commerical requirements.

UNIVERSITY OF WISCONSIN J?

Two types, utilizing the fused electrolyte and aqueous solutions,
are shown in the illustrations. (Fig. 50).

A study of the distillation and recovery of zinc direct from its
sulphide ores has yielded results of value, and the extraction of
molybdenum directly from its sulphide without the usual prelim-
inary roasting has been satisfactorily accomplished. The separa-
tion and recovery of several of the rare elements from their ores
is being studied by electrolytic and electrothermal methods.

FIG. 51.— 50,000 VOLT TRANSFORMER A

Investigation of the conductivity of various fused materials is
being made for the purpose of determining a suitable material for
an electrically heated fused bath for tempering high-speed tool
steel, the requirements of which are non-corrosive action on the
steel, and electrodes, and maintenance of the electrolyte without
decomposition or appreciable volatilization at about 1400 to
1500° C.

Other investigations deal with the fusion of quartz, reduction
of tungsten, commercial tests of the Edison storage cell, resistance

78 ELECTROLYTIC LABORATORIES

and counter electromotive force of copper refining tanks, and the
determination of such physical properties of carbon and graphite
as relate to the use of these materials for electrode purposes and
the construction of electric furnaces.

Among experimental work which has been done within the past
few years may be noted the determination of efficiency, cost and
commercial considerations relative to the production of hypo-
chlorites, tests on storage batteries of different makes, and upon
storage battery plants, and a comparison of most of the dry cells
on the market to determine their life, capacity, resistance, and
other properties. An extended investigation upon the corrosion
of iron showed, among other interesting facts, that iron under
strain causes a change in the contact potential of the metal toward
an electrolyte, so that a curve showing such changes is similar to
the curve of the stress-strain diagram.

An electrolytic stripping process was developed for the removal
of copper, brass and silver from iron. It has found extensive ap-
plication in the bicycle factories of the country as an adjunct to
the brazing process.-

Zinc plating has been the subject of a large amount of work,
and in addition to determining the conditions for the production
of the best deposits, a comparison has been made of the protective
properties of zinc applied by the electrolytic and by other methods.

A process has also been worked out for the deposition of dura-
ble, adherent deposits upon aluminium, as described in the Elec-
trochemical Industry, March, 1904. Another line of work to
which considerable attention has been given is the production of
chrome yellow and other pigments.

Various other researches which have produced interesting and
valuable results might be noted, but the ones mentioned serve to
indicate in general the nature of the work undertaken.

LEHIGH UNIVERSITY

The electro-metallurgical laboratory of the Lehigh University
at South Bethlehem, Pennsylvania, is supplied with direct current
at no volts, from the electrical laboratory, the main conductors
having a carrying capacity of ioo amperes. There are also in the
laboratory a Gulcher thermopile and three Cox thermopiles, for
small current work.

The laboratory has at its disposition a lecture room; a dark
room with equipment of microscope, goniometers and polariscopes
and drawing table; a room with appliances for crushing and
grinding ores, and apparatus for making and polishing thin sec-
tions ; an instrument room, with cases for instruments not in use
and balances, — a coarse balance, analytical balance, and button
balance; and with two working laboratory rooms which will be
more closely described.

The furnace room, or dry laboratory, is equipped with two wind
furnaces, a Pernot gas-furnace for use without blast, a Sefstrom
blast-furnace, a gas-fired muffle, a small engine and blower, a
Borcher's universal electric furnace, and a Moissan arc furnace ;
also a gas tank for storing any gas desired, cement floor, appara-
tus cases, and stone-topped table on brick piers for experiments.

The wet laboratory is equipped with sinks, two hoods with
steam baths, hot-air bath, chemical supply cases, and a stone-
topped centre-table for analytical work supplied with gas, blast,
suction, steam, water and waste-drip. Around the walls are six
working places, on oak tables, arranged for electrolytic work, as
follows :

Each working space has incandescent lamps of %, Va^A an d
four of i ampere, arranged in parallel, so that current may be ob-
tained in steps of % ampere up to 5 amperes. The measuring in-
struments are placed in a glass-front box, and consist for each
desk of a volt-meter with double scale, showing o to 5 or o to 50
volts, an ammeter with full scale 1 ampere, divided into fiftieths,
and an ammeter with full scale 10 amperes, divided into fifths.

ELECTROLYTIC LABORATORIES

Connecting-wires are led from the instruments to double binding
posts on the table, and connections can be thus made without
touching or jarring the instruments or opening the instrument
cases. Each working space has two large drawers and a stool,
and is plentifully supplied with flexible conductors of different
lengths with capped ends, thermometers, square and round glass-
jars, funnels, beakers, wash bottle, glass electrolytic stands, filter
stand, clamps, glass and rubber tubing, etc.

Fig. 52.

The wiring is all insulated aluminium wire, the joints being
made by looping the wires and passing a short screw-bolt through
the two loops, which on being screwed up flattens the soft wires
together and makes a very satisfactory joint, which is afterwards

LEHIGH UNIVERSITY 8l

taped. All short conductors are supplied with permanent brass
tips, soldered on, so as to avoid poor connections.

The wiring diagrams is as shown in Fig. 52, which will be
easily understood in connection with the description given.

Besides the equipment mentioned, each desk is supplied with
reversing switch, and resistance box. There are also in the labo-
ratory a number of extra voltmeters and ammeters of varying
capacity, a d'Arsenval galvanometer with reading telescope,
cylindrical wire wound rheostat, Ayrton plug shunt, Wheatstone
plug resistance bridge, Le Chatelier thermo-electric, Mesure and
Noel, and Wanner pyrometers, calorimeters, etc., etc.