Year: 1892

page_text: I then allow the solution to cool slowly in a crystallizing vessel in order to
separate therefrom the monocarbonate of soda in the crystalline form which may be
converted by heat into soda ash of high percentage or by carbonic acid gas into
bicarbonate of soda or by lime into caustic soda.
The mother liquor from the deposited crystals of monocarbonate of soda is
caused to pass successively through the carbonating apparatus the electrolytic cells
and the crystallizing tanks the required amount of chloride of sodium being added
from time to time to make up for that which has been decomposed thereby
rendering the cycle of electrolytic decomposition, bicarbonation, monocarbonation
and crystallization perfectly continuous.
In the electrolysis of chloride of potassium the electrolytic action is allowed to
proceed until nearly all the chloride is converted into carbonate and this is then
saturated with carbonic acid gas and the bicarbonate of potash which is precipitated
is filtered off which may be effected by the ordinary means.
The chlorine gas evolved from the anode compartment is led away continuously
during the electrolysis and may be utilised for any required purpose such as for
the manufacture of bleaching powder or chlorate of potash by any known or suitable
means.
Additions of the chloride may be made from time to time preferably in the solid
state to the solution in the first or any tank in order to replace the chlorides
decomposed.
The aforesaid tanks are preferably electrically connected in series and the cells
or compartments are preferably connected in parallel.
The carbon anodes mentioned above are composed preferably of a mixture of
anthracite, plumbago and pitch, which may be in the following proportions,
anthracite 2 parts, plumbago 2 parts and pitch 3 parts. This mixture is com-
pressed in a mould of a shape corresponding to that of the anode to be produced
and is heated to such a temperature as will effectually drive off any hydrocarbon
therein.
I find that it is advantageous to coke the anthracite before mixing it with the
pitch and plumbago and to heat the mixture preparatory to moulding it.
In heating the anodes of carbonaceous mixture so formed I prefer to embed them
in plumbago by which means I obtain a skin or coating of plumbago on the surface
of the anodes which greatly increases their life and conductivity.
In order to prevent leakage of the chlorine gas from the positive electrode
compartment it may be closed by a cover of insulating material the liquid level in
the negative electrode compartment constituting a seal. I find that it is best to
fasten, by means of cement, the carbon anode into the cover. This cement is made
preferably of equal parts of sulphur and kaolin.
Dated this 23rd day of December 1892.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, Agents.
COMPLETE SPECIFICATION.
Improvements in and Apparatus for the Manufacture of Chlorine
and Alkali by Electrolysis of Compounds thereof, and Anodes to
be employed therein.
I, EDWIN THORLEY PARKER of Newbridge House, Wolverhampton in the
County of Stafford, Electrician do hereby declare the nature of my invention and
in what manner the same is to be performed to be particularly described and
ascertained in and by the following statement :-
In the electrolysis of a solution of the chlorides of sodium or potassium chlorine
is set free at the positive pole electrode, caustic alkali being formed at the negative
pole electrode, owing to the presence of water.

page_text: Date of Application, 23rd Dec., 1892
Complete Specification Left, 25th Sept., 1893-Accepted, 28th Oct., 1893
PROVISIONAL SPECIFICATION.
Improvements in and Apparatus for the Manufacture of Chlorine
and Alkali by Electrolysis of Compounds thereof, and Anodes to
be employed therein.
I, EDWIN THORLEY PARKER of Newbridge House, Wolverhampton in the
County of Stafford, Electrician do hereby declare the nature of this invention to be
as follows:-
In the electrolysis of a solution of the chlorides of sodium or potassium chlorine
is set free at the positive pole electrode caustic alkali being formed at the negative
pole electrode owing to the presence of water.
If the electrolysis be conducted in a vessel in which the anode and cathode
compartments are divided by a porous diaphragm or partition the diffusion of the
electrolyte rapidly decreases the electro chemical efficiency but if carbonic acid gas
be passed through the cathode compartment any diffusion that may take place does
not to any material extent affect the original conditions of the electrolytic cell,
firstly, because chlorine gas has under those conditions no action upon the
carbonates of the alkalis and secondly because such carbonates are not decomposed
by the electric current. I prefer to heat the solution constituting the electrolyte
during electrolysis in order to prevent the absorption of the chlorine gas in the
chloride solution and consequently the conversion of the gas into hydrochloric acid
and also to decrease the electrical resistance of the cell. The heating may be
effected by steam coils in the tanks the coils being connected by joints of insulating
material to prevent leakage of electricity. The exhaust steam may pass into an
earthenware drain pipe.
According to my invention I may arrange a series of electrolytic tanks preferably
connected in series and each containing one or a number of cells with porous
partitions of suitable material such as burnt fire clay for instance. In these tanks
& cells I put preferably a saturated solution of the chloride to be electrolysed. The
said tanks themselves may constitute the negative electrode and for that purpose
may be made of iron.
The anodes may consist of carbon or of chromium phosphide. If of carbon they
may be made as hereinafter described.
A current of electricity preferably of a density of from 10 to 20 ampères per
square foot of cathode surface is passed through the cells for say from 5 to
10 ampere hours a portion of the chloride being thereby converted in the cathode
compartment into caustic alkali.
'
To start the cycle I then cause the electrolyte from the negative electrode
compartment to pass to a carbonating apparatus which is so arranged that carbonic
acid gas at ordinary or increased pressure (preferably drawn from a close lime kiln)
acts upon it in such a manner as to convert the whole of the caustic alkali into
bicarbonate of the alkali thus :-
NaHO + CO,= NaHCO,

page_text: If the electrolysis be conducted in a vessel in which the anode and cathode
compartments are divided by a porous diaphragm, or partition, the diffusion of the
electrolyte, rapidly decreases the electro-chemical efficiency but if carbonic acid
gas he passed through the cathode compartment, or compartments, any diffusion
that may take place does not to any material extent affect the original conditions
of the electrolytic cell firstly because chlorine gas has under these conditions but
slight action upon the carbonates of the alkalis and secondly because such
carbonates are not decomposed by the electric current. I heat the solution
constituting the electrolyte during electrolysis in order to prevent the absorptiou
of the chlorine gas in the chloride solution and, consequently, the conversion of the
gas into hydrochloric acid and also to decrease the electrical resistance of the cell.
The heating may be effected by steam coils in the tanks the coils being connected
by joints of insulating material to prevent leakage of electricity. I have found
that a suitable heat for the purpose is one of from about 115 degrees Fahrenheit
up to the boiling point of the solution. The heating has the further advantage of
keeping the solution in circulation. The exhaust steam may pass into an
earthenware drain pipe.
In carrying out my invention I may employ a series of electrolytic tanks, they
being preferably connected in series, and each containing one cell or a number of
cells with porous partitions of suitable material, such as burnt fire-clay for instance,
the cells, or compartments, of each tank being preferably connected in parallel.
In these tanks and cells I put a solution (preferably a saturated solution) of the
chloride to be electrolysed. The said tanks themselves may constitute the negative
electrode, and, for that purpose they may be made of iron.
The anodes may consist of carbon, or of chromium phosphide. If they be of
carbon they may be made as hereinafter described.
A current of electricity preferably of a density of from 10 to 20 amperes
(according to the internal resistance of the cell) per square foot of cathode surface,
is passed through the cells for say from 5 to 10 ampère hours, a portion of the
chloride being thereby converted, in the cathode compartment, into caustic alkali.
To start the cycle I then cause the electrolyte from the negative electrode
compartment to pass to a carbonating apparatus, which is so arranged that carbonic
acid gas, at ordinary, or increased pressure, (preferably drawn from a closed lime
kiln), acts upon it in such a manner as to convert the whole of the caustic alkali
into bicarbonate of the alkali thus :-
NaHO + CO₂ = NaHCо.
This solution of bicarbonate is circulated through the electrolytic tanks, thereby
transforming the caustic soda into carbonate thus :-
NamC, + Nano = Na₂CO + Hʊ.
T
1
Or I may start
+ Nano= Na,CO, H₂O.
cycle by the addition of sufficient bicarbonate of soda to the
electrolyte to convert preferably one half of the electrolysed chloride of sodium
into mono-carbonate the bi-carbonate of soda acting as a carrier of carbonic acid gas
to the electrolyte.
When the solution becomes electrolysed to the necessary point I allow it to cool
slowly in a crystallizing vessel in order to separate therefrom the mono-carbonate
of soda in the crystalline form, which may be converted by heat, into soda ash of
high percentage, or by carbonic acid gas, into bi-carbonate of soda, or by lime, into
caustic soda.
The mother liquor from the deposited crystals of mona-carbonate of soda is
caused to pass successively through the carbonating apparatus, the electrolytic
cells, and the crystallizing tanks, the required amount of chloride of sodium being
added from time to time to make up for that which has been decomposed thereby
rendering the cycle of electrolytic decomposition, bi-carbonation, mono-carbonation
and crystallization perfectly continuous.

page_text: In the electrolysis of chloride of potassium the electrolytic action and passage of
carbonic acid gas is allowed to proceed until nearly all the chloride is converted
into bi-carbonate of potash such bi-carbonate being filtered off by ordinary means.
The chlorine gas evolved from the anode compartment is led away continuously
during the electrolysis, and may be utilized for any required purpose, such as for
the manufacture of bleaching powder, or chlorate of potash, by any known or
suitable, means.
Additions of the chloride may be made from time to time, the said chloride being
preferably in the solid state, to the solution in the first, or any tank in order to
replace the chloride decomposed.
The carbon anodes herein before mentioned are composed preferably of a mixture
of anthracite coal, or coke made from anthracite coal, plumbago, and pitch, which
may be in the following proportions:-anthracite 2 parts, plumbago 2 parts, and
pitch 3 parts. This mixture is compressed in a mould of a shape corresponding to
that of the anode to be produced, and is heated to such a temperature as will
effectually drive off any hydrocarbon therein.
I find that it is advantageous to coke the anthracite before mixing it with the
pitch and plumbago and to heat the mixture preparatory to moulding it.
In heating the anodes of carbonaceous mixture so formed I prefer to embed them
in plumbago by which means I obtain a skin, or coating of plumbago on the surface
of the anodes which coating greatly increases their durability and conductivity.
In order to prevent leakage of the chlorine gas from the positive electrode
compartment it may be closed by a cover of insulating material the liquid level in
the negative electrode compartment constituting a seal.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is :-
1. In the manufacture of chlorine and alkali by electrolysis, the passing of
carbonic acid gas (carried in the form of bicarbonate) through the cathode
compartment, whilst the electrolyte, or solution, under treatment is subjected to
heat; substantially as herein before explained.
2. For the manufacture of chlorine and alkali by electrolysis, tanks, or cells, of
iron, constituting the negative electrode, and anodes of chromium phosphide,
substantially as hereinbefore described.
3. The manufacture of chlorine and alkali by electrolysis by subjecting a solution
of a chloride to electric action in the presence of carbonic acid gas and with the
application of heat, the current being conducted through the solution by means of a
cathode of iron and an anode of chromium phosphide; substantially as hereinbefore
described.
4. The manufacture of chlorine and alkali by electrolysis by subjecting a chloride
to the action of an electric current of from 10 to 20 ampères per square foot of
anode surface in the presence of excess of carbonic acid gas as bicarbonate and with
the application of heat substantially as hereinbefore described.
5. In the manufacture of chlorine and alkali by electrolysing a solution of a
chloride in electrolytic cells the employment of cells made of iron and provided
with means for heating the solution the said cells being in communication with a
carbonating apparatus into which the said solution passes from the cells and in
which the said solution is subjected to the action of carbonic acid gas under
pressure and from which it passes back to the electrolytic cells to be again subjected
to electrolysis substantially as hereinbefore described.
6. The manufacture of anodes for use in electrolysis by mixing anthracite coal
(or coke made from anthracite coal) plumbago and pitch and compressing the
mixture with or without, the application of heat; substantially as hereinbefore
described.
7. The manufacture of anodes for use in electrolysis by mixing and compressing
anthracite coal (or coke made from anthracite coal), plumbago and pitch, and

page_text: applying heat whilst the anodes are embedded in plumbago substantially as
herein before described.
Dated this 25th day of September 1893.
J. H. JOHNSON & Co.,
Agents.