Improvements in Electrolysis.
Year: 1896

page_text: Date of Application, 29th July, 1896-Accepted, 1st. May, 1897
COMPLETE SPECIFICATION.
Improvements in Electrolysis.
1, GRAYDON POORE, of 9, Cowcross Street (late of 47, Cannon Street), in the
City of London, Engineer, do hereby declare the nature of this invention and in
what manner the same is to he performed to be particularly described. and
ascertained in aud by the following statement:-
My invention has reference to a new method of depositing metals and decomposing
salts by electrolysis, and has for its object the overcoming of objections and
difficulties which obtain with the systems at present in use and the production with
rapidity and economy of sound and homogeneous deposits.
In depositing copper and other metals by the methods most commonly employed
the anode and cathode are placed in a bath containing metallic salts in solution and
are connected by conductors to a suitable electric generator so that when an
electric current is passed the anode is dissolved and the metal is deposited on the
cathode.
Now in practice it is found that during the process of deposition there is a
tendency to decompose the liquid as well as the salts so that there is a generation
of gas which forms bubbles on the surface of the plates; these bubbles cause
partial insulation of the plates with the result that the deposit becomes irregular
and wanting in homogeneity.
To mitigate these evils various plans have been devised such as the movement or
oscillation of the plates, the agitation of the liquid, or the mechanical rubbing of
the surface of the cathode so as to expel or disperse the gas bubbles, but these
devices are only partially successful, and in all cases it has hitherto been necessary
to perform the operation of electrolysis slowly and consequently with considerable
expense.
It will be understood that the essential reason of the generation of the gas
referred to is that during the process of deposition that portion of the solution
which is in immediate contact with the cathode becomes rapidily impoverished so
that consequently the electric current tends to decompose the liquid and to produce
hydrogen and oxygen gases. The agitation of the liquid or oscillation of the
plates only partially obviates this, as it is found in practice impossible to obtain a
circulation which shall always maintain the liquid in contact with the cathode up
to a constant degree of strength, or in other words to deliver to the surface of the
cathode a supply of the metallic salt as quickly as it is deposited.
Now according to my invention I dispense with the submersion of the cathode
in a bath and maintain a supply of the solution to the surface of the cathode at a
constant degree of strength, and at the same time mechanically remove and cause
the instant dispersion of any gas bubbles which may be formed during the process
of deposition.
By these means the process can be carried on with very great rapidity and
consequent economy, whilst the deposit is sound and homogeneous.
In carrying out my invention I employ a receptacle containing a solution of
metallic salts and I suspend or retain the cathode in such a position that by the aid
of a pump or equivalent it can receive upon its surface a stream, spray, or jet of
G

page_text: the liquid, the said stream or jet constituting the only electrical connection between
the anode and cathode and having sufficient force and velocity to immediately-
dislodge any particles of gas which may tend to attach themselves to the cathode..
By this means a continuous supply of unimpoverished solution is directed on to
the cathode upon the surface of which deposition of the metal instantly takes
place.
The anode may be either the insoluble nozzle through which the jet or stream
passes, in which case the strength of the solution must be maintained from some
outside source, or it may be from a plate of the required metal placed directly in
the stream of liquid, or the nozzle itself may be composed wholly or in part of
the metal required to be deposited.
To insure the regular deposition of the metal I may cause the cathode to be
moved in front of the jet so that its surface is equally exposed to the stream. In
some cases I cause the jet to be moved so that the stream can be directed over the
surface or I may employ both arrangements together.
I have appended a drawing illustrating one means of performing my invention in
the production of printers' electrotypes.
Fig. 1 is a plan, and Fig. 2 a section on line 1-2 thereof.
B represents the receptacle containing the metallic gólution to about the depth
shown, C is the cathode or mould laid and fixed upon a table T adapted to be
moved to and fro clear above the said solution by an eccentric arrangement as
shown at E E' or in any suitable manner. P is a pump driven as shown at P¹ or
in any convenient manner, S its suction pipe from the solution in B, D its delivery
pipe terminating in a fish-tailed nozzle N disposed above the line of travel of the
moving table T and cathode C, and of sufficient width to enable the jet to
completely cover the cathode. When the jet is to be moved over the cathode a
flexible pipe and trolley device may be employed operated in any convenient way.
The electric connections from the source of supply are made respectively to the
unsubmerged cathode and to a part of the nozzle as at L L so that as above
stated the liquid of the jet itself constitutes the only electrical connection between
them.
To make up for impoverishment and maintain the strength of the solution after
it has acted upon the cathode C and returned to the receptacle B I have illustrated
the employment of a perforated tray at F fixed in the receptacle B and filled with
the required salt through which the spent liquor permeates in returning, but as
above stated the nozzle N may itself he composed of the required metal which will
be apparent without illustration.
It is to be understood that 1 in no sense limit the arrangement. to that shown as
I may suspend the cathode vertically or in any convenient way and dispose the
conducting jet, pump, and parts to correspond.
It will be seen that my invention may be applied to the deposition of metals for
many purposes amongst which may be mentioned
1. The production of electrotypes.
2. The purification of metals.
3. The electro-plating and production of various articles of commerce.
4. The decomposition of metallic salts.
Having now particularly described. and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what
I claim is :-
1. In electrolysis, instead of a bath, the use of a jet of electrolyte through
which a current of electricity is passed, the liquid of such jet constituting the only
electrical connection between the anode and unsubmerged cathode.
2. In electrolysis wherein a jet is employed as the only electric connection
between anode and cathode, moving the anode and unsubmerged cathode relatively
to one another for the purpose set forth.

page_text: 3. The process or method of producing electrotypes, electroplating, decomposing
metallic salts, and so forth conducted substantially as herein described.
Dated this 29th day of July 1896.
J. C. CHAPMAN,
70, Chancery Lane, London, W.C., Chartered Patent Agent..