IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR DEPOLARIZING ELECTROLYTIC BATHS IN THE REFINING AND DEPOSITION OF METALS
Year: 1883

page_text: LETTERS PATENT to Alexander Melville Clark of the firm of A. M and
W. Clark of 53 Chancery Lane in the County of Middlesex Fellow of the
Institute of Patent Agents for an Invention of IMPROVEMENTS IN THE
METHOD OF AND APPARATUS FOR DEPOLARIZING ELECTROLYTIC BATHS IN THE
REFINING AND DEPOSITION OF METALS communicated to him from abroad
by Constant de Changy, of the City of Levallois-Perret (Seine) France
PROVISIONAL SPECIFICATION left by the said Alexander Melville Clark at
the Office of the Commissioners of Patents on the 4th May 1883.
ALEXANDER MELVILLE CLARK of the firm of A. M. and W. Clark of 53
Chancery Lane in the County of Middlesex Fellow of the Institute of Patent
Agents "IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR DEPOLARIZING
ELECTROLYTIC BATHS IN THE REFINING AND DEPOSITION OF METALS [commu-
"
nicated to him from abroad by Constant de Changy, of the City of Levallois-Perret
(Seine) France]
The object of this Invention is to obtain a maximum amount of metal for the
quantity of electric current used; and the Invention consists in organizing the
electrolytic bath in such a manner that the plates or bath anodes and cathodes
are constantly kept depolarized in the manner more fully hereafter described.
Heretofore, in the refining of metals by electricity or in the deposition of metals
on different substances, a secondary action always takes place on the surface of
each plate, for the reason that an extra-current is produced simultaneously with the
transposition of the metal from one plate to the other. This action is detrimental
to the success of the operation whether it is intended to simply refine metal, or to
deposit gold, silver, copper, or other metals on different objects..
With the system of apparatus of this Invention, these objections are entirely
avoided.
In the accompanying drawing Figure 1 is a perspective view, and Figure 2 an

page_text: elevation of what I call a "depolarizer" of the plates. The same letters indicate
the same parts in both figures.
The electrolytic baths containing the plates are not shown, nor is there any need
to describe them as they are well known.
For connecting the depolarizer to an electrolytic bath, I have selected the
following method:-After having connected the plates of the bath to a generator
of electricity or dynamo-machine in such a manner as to form a closed circuit, I
connect to one pole of the electrolytic bath a wire which leads to post No 1 of the
depolarizer connecting with the electro magnet having the helix of the same cross
section as the principal circuit and communicating with a bar of copper g placed
above the armature which comes into contact therewith by the attraction of the
electro magnet. When this contact is formed the current runs through the
armature C to post h of the armature, thence through wire i of this electro magnet,
and thence to post N° 2. The two posts of the dynamo machine are connected
with the two leading wires which communicate, one (the negative for instance) with
a plate of the electrolytic bath, and the other with the post N° 1 of the depolarizer,
thence through the depolarizer as described to post N° 2 which is also connected
by a wire with the other pole of the electrolytic bath.
From the two leading cables a derivation circuit is taken and connected with the
two posts ff of the electro magnets having the helix of fine wire. By this
disposition, the electrical circuit is completely interrupted between the electrolytic
bath and the dynamo machine, thus preventing the secondary current from
circulating through it, and also preventing the machine from changing polarity.
When the dynamo machine is set in motion and the circuit to the leading wire is
closed, through the helix of the electro magnet having the fine wire, the machine
charges itself (thus preventing the reversion of the current.) The electro magnet
being charged, the iron armature D inserted in the copper bar or. armature C is
attracted, thus making electrical connection with the copper bar g which must
make good contact to allow the current to circulate freely through the helix of the
electro magnet A (which helix is made of the same diameter as the leading wires)
to go to the bath. The resistance of the helix being very small, the current will
pass through this, and none or very little through the helix of the other electro
magnet B having the fine wire thus keeping always charged the electro magnet A
which keeps constantly the bar C in contact with g. This is the apparatus which
serves at the same time to depolarize the electrolytic bath and which is accomplished
in the following manner; the two poles of the bath are connected with the two
posts N° 3 which communicate with the copper contact postse e thus completing
the circuit of the bath, either both when the machine is in motion or at rest. By
this operation, any static charge which the bath might have assumed during the
passage of the current is immediately discharged, and the bath consequently
depolarized
i
:
It will be understood that the action of the current, especially that generated by
a dynamo machine on liquids containing metallic plates, has a tendency to create
secondary currents, as well as to charge both the plates and the liquid statically.
Now therefore, by means of the depolarizer, I continually and automatically
discharge both plates and liquid from their static condition.
The armature C of the depolarizer when properly adjusted by means of retractile
springs, vibrates between the electro magnets A and B and the posts e e thus making
and breaking, or diminishing and increasing the contact with g; and approaching
or making contact, with the standing posts e e which latter serve to discharge the
bath as before stated.
It will also be understood that I do not limit myself to any particular
construction of the depolarizer, as, for instance, it may be composed of a series of
plates insulated from each other, having their termini connected either with the
earth, or with plates placed near each other when the depolarization of the bath will
take place.
'L'

page_text: The electrolytic bath may be connected either for tension or in multiple are.
When the plates are connected in derived circuit the depolarizer must be connected
in multiple are with the pole of each circuit, taken from the main circuit.
I have found in practice that it is both advisable and economical to use currents
of somewhat high tension, in order to more easily overcome the resistance offered
by the different baths when connected for tension but I have also noticed that the
current is apt to pass through the liquid, without producing electro chemical
decomposition. To prevent this action I therefore connect first a number of baths
in series;
and then, take either from all or any of them, derived currents, to actuate
other baths.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Alexander Melville Clark in the Great Seal Patent Office on the
3rd November 1883.
ALEXANDER MELVILLE CLARK of the firm of A. M. & W. Clark of 53
Chancery Lane in the County of Middlesex, Fellow of the Institute of Patent
Agents "IMPROVEMENTS IN THE METHOD OF AND APPARATUS FOR DEPOLARIZING
ELECTROLYTIC BATHS IN THE REFINING AND DEPOSITION OF METALS.” A commu-
nication to me from abroad by Constant de Changy of the City of Levallois-Perret
(Seine) France
The object of this invention is to obtain a maximum amount of metal for the
quantity of electric current used; and the invention consists in organizing the
electrolytic bath in such a manner, that the plates or both anodes and cathodes are
constantly kept depolarized in the manner more fully hereafter described. Here-
tofore, in the refining of metals by electricity or in the deposition of metals on
different substances a secondary action always takes place on the surface of each
plate, for the reason that an extra-current is produced simultaneously with the
transposition of the metal from one plate to the other. This action is detrimental
to the success of the operation, whether it is intended to simply refine metal or to
deposit gold, silver, copper or other metals on different objects. With the system
of apparatus of this Invention, these objections are entirely avoided. The Invention
is illustrated by way of example in the accompanying drawing figure 1 of which
shows a front view, figure 2 an end view and figure 3 an underside plan of what
I term a depolarizer of the plates.
The electrolytic baths containing the plates are not shown, nor is there any need
to describe them, as they are well known. For connecting the Depolarizer to an
electrolytic bath I adopt the following method:
After having connected the plates of the bath to a generator of electricity or
dynamo machine in such a manner as to form a closed circuit, I.connect to one pole
of the electrolytic bath a wire which leads to binding post No. 1 of the depolarizer,
connecting with the electro-magnet B whose coil is of the same cross section as the

page_text: principal circuit, and communicating with the bars of copper g placed above the
armature which come into contact therewith by the attraction of the electro-
magnet. When this contact is formed the current runs through the armature C to
the post h to which the armature is pivoted thence through wire i of the electro
magnet to binding post No. 2. The two poles of the dynamo machine are con-
nected with the two leading wires which communicate, one (the negative for
instance) with a plate of the electrolytic bath, and the other with the binding
post No. 1 of the depolarizer thence through the depolarizer, as described, to
post No. 2 which is also connected by a wire with the other pole of the electrolytic
bath.
From the two leading wires a derivation circuit is taken, and connected with
the two binding posts f. f to which the ends of a fine wire electro magnet A are
attached. By this disposition the electric circuit is completely interrupted between
the electrolytic bath and the dynamo machine, thus preventing the secondary
current from circulating through it, and also preventing the machine from changing
polarity. When the dynamo machine is set in motion and the circuit to the
leading wires is closed through the fine wire electro magnet the machine charges
itself (thus preventing the reversal of the current). The electro magnet being
excited the iron armature D inserted in the copper bar, or armature C is attracted,
thus making electrical connection with the copper bars g, which must make good
contact to allow the current to circulate freely through the coil of the electro
magnet B (which coil is made of wire of the same sectional area as the leading
wires) to go to the bath. The resistance of the coil being very small, the current
will pass through this, and none or very little through the coil of the other electro-
magnet A baving the fine wire, thus keeping always charged the electro magnet B
which keeps the bar C constantly in contact with g.
This apparatus serves at the same time to depolarize the electrolytic bath which
is accomplished in the following manner; the two poles of the bath. are connected
with the two binding posts No. 3 which communicate with the copper.contact
posts e e thus completing the circuit of the bath, both when the machine is in
motion or at rest. By this operation any static charge which the bath might have
acquired during the passage of the current, is immediately discharged, and the bath
consequently depolarized.
It will be understood that the action of the current (especially that generated
by a dynamo machine) on liquids containing metallic plates, has a tendency to
create secondary currents as well as to charge both the plates and the liquid
statically. Now therefore, by means of the depolarizer, I continually and auto-
matically discharge both plates and liquid from their static condition. The
armature C of the depolarizer, when properly adjusted by means of retractile
springs, vibrates between the electro magnets A and B and the posts e e. thus
making and breaking, or diminishing and increasing the contact with g, and
approaching or making contact with the posts è e which latter serve to discharge
the bath as before stated.
It will be understood that I do not limit myself to any peculiar construction of
the depolarizer as for instance, it may be composed of a series of plates insulated
from each other, having their terminals connected either with the earth, or with
plates placed [near each other whereby the depolarization of the bath will take
place.
The electrolytic bath may be connected either for tension or in multiple arc.
When the plates are connected in derived circuit the depolarizer must be connected
in multiple are with the pole of each circuit, taken from the main Circuit. I have
found in practice that it is both advisable and economical to use currents of some-.
what high tension, in order to more easily overcome the resistance offered by the
different baths when connected for tension, but I have also noticed that the current
is apt to pass through the liquid, without producing electro-chemical decomposition.
To prevent this action I therefore connect first a number of baths in series and
then take either from all, or any of them, derived currents to excite other baths,

page_text: Having described the nature of the said Invention and the manner of performing
the same I declare that what I claim as the Invention to be protected by the
hereinbefore in part recited Letters Patent is :
1 The method of automatically depolarizing electrolytic baths which consists
in breaking, diminishing or increasing the contact of the main circuit and making,
approaching or receding from a contact, with the circuit of the electrolytic bath
or baths, with or without breaking the main circuit, substantially as herein
described.
2nd The combination of two electro-magnets as herein described with the
armature C, the contact posts e e and the copper bars all substantially as shown
and described.
3rd The combination of electro-magnets A and B armatures C and D contact
posts e e binding posts Nos. 1. 2. 3 and ff with their connecting wires and
electrolytic baths (not shown) and a generator of electricity.
4 The combination of an electrical generator; electrolytic baths connected in
tension, and also in derived circuits, and a depolarizer substantially as shown and
described.
In witness whereof I the said Alexander Melville Clark have hereunto set my
hand and seal this third day of November A.D. 1883.