A New Process of Electrolysis, and Apparatus therefor.
Year: 1895

page_text: Da'e of Application, 8th Mar., 1895-Accepted, 4th May, 1895
COMPLETE SPECIFICATION.
A New Process of Electrolysis, and Apparatus therefor.
I, EMILE ANDREOLI, of 18 Somerleytou Road, Brixton, in the County of
London, Journalist, do hereby declare the nature of this invention and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement :-
The object of this invention is a new process of electrolysis which I will call
"indirect" electrolysis.
According to my invention the anode and cathode to which the electric
generator is connected are situated in compartments of a vessel the said com-
partments being formed by two porous partitions, and the said compartments
containing suitable electrolytes. The solution to be treated by the indirect
electrolysis is contained in or passed through a compartment, situated between the
anode and cathode compartments.
The indirect electrolysis takes place in the central compartment which contains
metal, carbon or the like in the form of plates gauzes pieces or in any suitable
form and of a character in accordance with the solution, and these metal plates
gauzes pieces or the like are not connected with either the cathode or anode in the
adjoining compartments, nor with the poles of the dynamo or electric generator.
I will give two illustrations of the applications of my invention; first, to the
reduction of a bisulphite of sodium solution to the state of hydrosulphite of sodium
which is a very powerful bleaching agent; secondly, to the precipitation and
deposition of gold, or silver, or the like from their solution, froin which also the
other applications of the invention will be understood.
In the first case, in the positive compartment of the tank, the electrolyte will
be for instance a caustic potash solution and in the negative compartment it will
be a chloride of sodium solution but I may use other convenient electrolytes. The
liquid in the central compartment is a solution of bi-sulphite of sodium in which
are immersed zinc or other suitable plates pieces gauzes or the like not connected
with the anode and cathode nor with the electric generator. As soon as the
current passes through the tank, the solutions in the positive and negative com-
partments are decomposed in the usual manner and the bi-sulphite of sodium is
transformed into hydrosulphite of sodium.
The bi-sulphite solution may flow from a reservoir successively through several
such tanks connected in series by suitable pipes or passages and be pumped back
to the reservoir which can be used as a bleaching tank from which it passes again
through the central compartment of the electrolyser where it recovers the bleaching
properties. The solution may be used over and over again, before it requires an
addition of fresh bi-sulphite of sodium to maintain its strength. Other liquids
can be submitted to the indirect or secondary electrolysis and the anolyte and
catholyte as well as the metal of the plates gauzes pieces or the like which dip in
the central compartment may be varied as may be convenient.
I will now describe the precipitation or deposition of gold or other metals
according to my invention.
In the usual electro-depositing tanks there are two electrodes, viz., an anode and
a cathode. Gold, silver or other metal is deposited on the cathode and both the
anode and the cathode are dipped in the metallic solution.
In carrying out my invention as applied for example to the obtainment of gold
from its solutions, the metallic plates or perforated sheets, gauzes, pieces or the like,
on which the metal will be precipitated, are placed in the central compartment

page_text: between the positive and negative electrodes, which work in any convenient
electrolyte in their respective compartments.
There is no netal precipitated on the cathode as in the ordinary electro
deposition of metals, but the gold is precipitated on the said sheets gauzes pieces
or the like which, if in the form of plates or sheets, are preferably perforated and
may be made of lead, zinc, silver, or other suitable metal or inaterial and be
disposed vertically or horizontally or in other convenient position over or near
each other in the central compartment and which are not connected in any way to
the anode or cathode in the next compartment nor to the poles of the dynamo or
electric generator.
The indirect electrolysis precipitates the gold on the whole, and on the two sides
of the perforated sheets plates gauzes pieces of metals or the like which are in the
central compartment, and which adjoin the positive compartment.
The solution containing gold is in, or passes through the central compartment
in which the said metallic plates gauzes or pieces or the like are placed and where
the indirect electrolysis is set up under the influence of the true anode and cathode,
which, each in its respective compartiment, and in any convenient electrolyte work
independently. This indirect electrolysis in the central compartment precipitates
or deposits on the plates gauzes pieces or the like immersed in the solution
containing the gold until the strong or weak metallic solution, is practically
exhausted.
The mode of arrangement of the perforated sheets or plates, gauzes or pieces
of metal, or the like conducting material in the central compartiment may be varied
according to circumstances, but it must be understood that the more the central
compartment contains of such sheets plates gauzes pieces or the like the better and
quicker the deposition of gold on their surface will be effected by the indirect
electrolysis. It is advisable to avoid the contact of the plates or the like disposed
on the side of the porous diaphragm of the positive compartment, with a plate or
plates or the like on the side of the porous diaphragm of the negative
compartment.
To effect this I coat a perforated plate of zinc or other metal with paraffin or
other insulating substance on the side which will face or touch the other plates
or the like, or I separate it from them by means of glass tubes, or other
insulators.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is:
1
1. The herein before described process of indirect electrolysis which consists in
placing solutions in, or causing them to pass through a central compartment
containing perforated metallic plates sheets gauzes or pieces of metal or the like,
not connected with the anode and cathode in the adjoining compartments nor with
the poles of the electric generator, the electric current being applied by means of
an anode and cathode situated in the above mentioned compartments.
2. For the indirect electrolysis of solutions a tank divided in three compartments
by two porous diaphragms constituting a third compartment for containing the
solution to be subjected to the indirect electrolysis, provided with metallic plates
or their equivalents not connected with the true electrodes nor with the poles of the
electric generators and compartment at each side of the central compartment,
the said side compartments respectively containing a convenient electrolyte and
the anode and cathode connected to the electric generator substantially as
hereinbefore described.
Dated this 8th day of March 1895
JOHNSONS & WILLCOX,
Agents.