New or Improved Process and Apparatus for the Electrolytio Decomposition of Common Salt.
Year: 1894

page_text: Date of Application, 19th Mar., 1894
Comolete Specification Left, 18th Dec., 1894-Accepted, 19th Jan., 1895
PROVISIONAL SPECIFICATION.
New or Improved Process and Apparatus for the Electrolytio
Decomposition of Common Salt.
I, CASTLE SMITH, of 54 Fleet Street, in the City and County of London,
Gentleman, do hereby declare the nature of this invention, as communicated
to me from abroad by Gersdorf Jorgensen, of Bergen, Norway, to be as
follows:-
My invention has for its object an improved process and apparatus for decom-
posing a solution of common salt by the aid of an electric current, to produce
chlorine gas and caustic soda.
For the purposes of my invention I use for containing the electrolyte a vat or
vessel of an U shape, constructed of granite, slate or other material lined with a
suitable non-conducting substance.
At the bottom of one of the upright or vertical portions of this vessel I arrange
an insulated carbon plate from which projects upwards one or more rods of retort
coal forming the anode, the whole being enclosed in a cylindrical cover of porous
material having a pipe connected to the upper end thereof for the escape of the
chlorine gas evolved.
In the second upright or vertical portion of the vessel I place an iron plate
forming the cathode and near this is the outlet pipe for the sodium hydroxide.
With such a vat or containing vessel having the anode and cathode arranged
therein as above described the collection of the ions at the proper points during
the process of decomposition will be materially assisted, and this may be ensured
to a still greater extent by arranging in that portion of the vessel containing the
cathode and above the latter a centrifugal apparatus of any suitable construction.
The supply of the solution to the vat or containing vessel is effected preferably
from a tank situated at a higher level and connected to the bottom of the horizontal
portion of the vat by a suitable pipe.
Dated this 10th day of March 1894.
CASTLE SMITH,
Invention" Office, 54, Fleet Street, London, E.C.
New or Improved Process and Apparatus for the Electrolytic
Decomposition of Common Salt.
I, CASTLE SMITH, of 54 Fleet Street, in the City and County of London,
Gentleman, do hereby declare the nature of this invention and in what manner
the same is to be performed, as communicated to me from abroad by Gersdorf
Jorgensen, of Bergen, Norway, to be particularly described and ascertained in and
by the following statement:-
My invention has for its object an improved process and apparatus for decomposing

page_text: a solution of common salt by the aid of an electric current to produce chlorine
gas and caustic soda, the latter being subsequently purified by a continuation of the
process.
For the purposes of my invention I use for containing the electrolyte a closed
vat or vessel of an U shape, constructed of granite, slate or other material lined
with a suitable non-conducting substance.
. One of the upright or vertical portions of this vessel is divided from the
remainder thereof by means of a porous partition or by inserting therein a porous
vessel of suitable size and shape, and into this divided off portion of the containing
vat or vessel or the porous vessel contained in it project the lower ends of one or
more rods of retort coal forming the anode, and those upper ends, which extend
through the top of this vat or of the porous vessel contained therein, are connected
together by a carbon plate or metallic binding preferably of lead in electrical
connection with one of the wires of the electric circuit.
In the second upright or vertical portion of the vessel I place an iron plate or
perforated receptacle forming the cathode, and to this the second wire of the
electric circuit is connected.
Suitable inlets and outlets are provided at proper points in the vat for the
charging and discharging of the contents thereof.
A vat constructed as above described is shown in sectional elevation in the
accompanying drawings. In this A is the vertical portion of the vat containing
the anode formed of sticks of retort coal a connected to the plate or binding a,
and B the vertical portion containing the cathode which may be either in the form
of an iron plate or perforated cylinder b. The part A is divided off from the
remainder of the vat either, by a porous division plate or a porous vessel c fitting
into it, the anode room thus formed being provided with charging pipe d and exit
pipe e for the chlorine gas evolved during electrolysis whilst the remainder of the
vat is provided with charging pipe f, an outlet pipe 9 for the hydrogen evolved, and
outlet pipe for the sodium hydroxide.
In carrying my process into effect by the aid of the above described vat both
compartments A and B are charged with the solution of common salt and the latter
decomposed by the passage of an electric current through it. Chlorine gas is
thereby evolved in the anode room A and sodium in the cathode room B forming
mixtures of hydroxide, chloride and hypochlorite of sodium.. The sodium
hydroxide thus obtained I then purify in a series of similarly constructed vats in
any of the following ways:-
1. By filling the anode room of the second or subsequent vat with a strong
solution of common salt and the cathode room of the same vat with the electrolysed
solution from the cathode room of the first vat ;
2. By filling the anode room of the second or subsequent vat with the electrolysed
solution from the cathode room of the first vat and the cathode room of the second
vat with water, to which, in order to further the process a little caustic soda may
be added and the water kept warm ;
3. By filling the whole of the second or subsequent vat with the electrolysed
solution from the cathode room of the first vat;
4. By using in any of the anode rooms strong solution of common salt and in the
cathode rooms pure water, to which as in process 2 a little caustic soda may be
added and the water kept boiling; the solutions are then electrolysed in the
ordinary way.
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.) The process of electrolytically decomposing solutions of common salt and
purifying the caustic soda obtained by such composition substantially as described.
(2.) In the electrolytic decomposition of solutions of common salt a vat of

page_text: U section the interior of which is divided by a porous partition or a porous vessel
fitting into one of the vertical portions thereof substantially as described and
illustrated in the accompanying drawings.
Dated this 15th day of December 1894.
CASTLE SMITH,
Invention" Office, 54, Fleet Street, London, E.C.