Manufacture of Caustic Soda and Potash and Hydrochloric Acid by Electrolytic Treatment of Chloride of Sodium and Chloride of Potassium, and Apparatus for this Purpose.
Year: 1892

page_text: Date of Application, 22nd Aug., 1892
Complete Specification Left, 20th May, 1893-Accepted, 22nd July, 1893
PROVISIONAL SPECIFICATION.
Manufacture of Caustic Soda and Potash and Hydrochloric Acid by
Electrolytic Treatment of Chloride of Sodium and Chloride of
Potassium, and Apparatus for this Purpose.
We, JEAN PAUL ROUBERTIE, of 15 Rue de Lyon, Bordeaux, Gironde, Chemist,
VICTOR LAPEYRE, of 54 Rue de Prony, Paris, Civil Engineer, and ULYSSE
GRENIER, of Ponyand, Dordogne, Proprietor, do hereby declare the nature of this
invention to be as follows:-
When a solution of chloride of sodium is treated by electrolysis, there is produced,
firstly at the negative pole, sodium, (which in combining with the elements of water,
forms caustic soda) and hydrogen; secondly, at the positive pole, chlorine is
generated which afterwards forms compounds with oxygen.
In the processes heretofore employed, it has been endeavoured to utilise the
chlorine which is given off at the positive pole, but we have found that the
presence of this gas and its oxygen compounds operates detrimentally upon
the proper working of the electrolytic action.
Our invention has for its object to bind the chlorine as it is generated and to
transform it into hydrochloric acid, employing by preference for this purpose the
hydrogen which is given off at the negative pole.
By this means we avoid not only the formation of the oxygen compounds of the
chlorine, but also the presence of the latter in a free state in the electrolytic.
apparatus.
We utilise for this purpose the affinity of hydrogen for chlorine, such affinity
being so energetic when these substances are produced by electrolysis that the
combination can be effected in diffused light.
The hydrochloric acid formed in this manner will not mix with the solution of
the chloride of sodium or potassium in the electrolytic bath but will form a
supernatant layer on its surface, which can readily be decanted.
The apparatus employed for the purposes of our invention may be variously
arranged, but in all constructions it consists essentially of two chambers separated
from each other at the upper part and resting upon a bottom vessel containing the
chloride of sodium, with which they both communicate, the chambers being either
rectangular and formed in one piece with an intervening partition, or they may be.
separate vessels, either of cylindrical or other form.
The chambers may be made of wood lined with a material that is not acted upon
by acids or alkalies, such as cement, glass, &c.
The bottom vessel is charged with sea salt or with chloride of potassium through
The bottom
the open tops of the chambers, which are then closed by covers.
vessel is also charged through pipes with a saturated solution of sea salt or chloride
of potassium. The one chamber has placed within it the iron negative electrodes
situated above the layer of sea salt, and connected with the negative pole of the
electric generator employed; they are formed of a series of vertical iron plates
connected together. The other chamber contains the positive electrodes, which are
placed in slanting positions and connected to the positive pole of the generator.
They are of any suitable metal silvered, or of lead, or of silvered glass.
They might also be of carbon. The negative chamber is closed hermetically,
with an escape pipe for leading off the hydrogen gas, the withdrawal of which may
be accelerated by a pump, which forces the gas into the positive compartment
through a pipe opening underneath the positive electrodes, so that the gas, issiting
in small bubbles through perforations, passes up along the inclined surfaces of the
electrodes and combines with the nascent chlorine as this forms on the electrodes;
*****

page_text: thus producing hydrochloric acid, which rises to the top of the electrolyte and flows
off through a lateral opening. The soda or potash solution formed in the negative
chamber also passes up to the surface of the electrolyte with the hydrogen gas and
flows off through a lateral passage, to be concentrated elsewhere. A discharge pipe
for the spent electrolyte is provided at the bottom of the negative chamber.
The supply and discharge of the liquids is regulated according to the intensity of
the electric current employed.
The flow may be arranged to take place either continuously or intermittently.
In some cases the supply of the salt solution can take place from the top of the
negative chamber and the caustic soda or potash solution be discharged at
bottom.
The negative electrode may also be formed by a helically coiled plate, when the
chambers are of cylindrical form, and the positive electrode may be made of funnel
shape, leaving an annular space between its upper edge and the sides of the chamber
for the escape of the hydrochloric acid.
In order to facilitate the combination of the hydrogen and chlorine gases, it is
advantageous to subject them to the influence of a strong light, for which purpose
the apparatus may be made of glass and the daylight projected into it by means of
strong reflectors, or one or more electric lamps may be placed within the negative
chamber when this is of opaque material.
Dated this 22nd day of August 1892.
ABEL & IMKAY,
Agents for the Applicants.
COMPLETE SPECIFICATION.
Manufacture of Caustic Soda and Potash and Hydrochloric Acid by
Electrolytic Treatment of Chloride of Sodium and Chloride of
Potassium, and Apparatus for this Purpose.
We, JEAN PAUL ROUBERTIE, of 15 Rue de Lyon, Bordeaux, Gironde, Chemist,
VICTOR LAPEYRE, of 54 Rue de Prony, Paris, Civil Engineer, and ULYSSE
GRENIER, of Ponyaud, Dordogne, Proprietor, do hereby declare the nature of this
invention and in what manner the same is to be performed to he particularly
described and ascertained in and by the following statement :-
When a solution of chloride of sodium is treated by electrolysis, there is
produced, firstly at the negative pole, sodium, (which in combining with the
elements of water, forms caustic soda) and hydrogen; secondly, at the positive
pole, chlorine is generated which afterwards forms compounds with oxygen.
In the processes heretofore employed, it has been endeavoured to utilise the
chlorine which is given off at the positive pole, but we have found that the presence
of this gas and its oxygen compounds operates detrimentally upon the proper
working of the electrolytic action.
Our invention has for its object to bind the chlorine as it is generated and to
transform it into hydrochloric acid, employing by preference for this purpose the
hydrogen which is given off at the negative pole.
By this means we avoid not only the formation of the oxygen compounds of the
chlorine, but also the presence of the latter in a free state in the electrolytic
apparatus.
We utilise for this purpose the affinity of hydrogen for chlorine, such affinity
being so energetic when these substances are produced by electrolysis that the
combination can be effected in diffused light.
As source of hydrogen, as already stated, we employ by preference that which
is given off at the negative pole of the electrolytic bath, and this bydrogen which,
in the processes at present employed, is a source of electrical resistance, becomes an
auxiliary in conveying it to the positive electrode where it comes in contact with
the chlorine which is there disengaged and forms with it hydrochloric acid under
the influence of light.

page_text: The hydrochloric acid formed in this manner will not mix with the solution of
the chloride of sodium or potassium in the electrolytic bath but will form a
supernatant layer cn its surface, which can readily be decanted.
The apparatus employed for the purposes of our invention may be variously
arranged, but in all constructions it consists essentially of two chambers separated
from each other at the upper part and resting upon a bottom vessel containing the
chloride of sodium, with which they both communicate, the chambers being either
rectangular and formed in one piece with an intervening partition, or they may be
separate vessels, either of cylindrical or other form.
The chambers may be made of wood lined with a material that is not acted
upon by acids or alkalies, such as cement, glass &c.
In the arrangement shewn in longitudinal section, cross section and plan at
Figs. 1, 2 and 3 of the accompanying drawings, A is a rectangular vessel either of
wood and glass combined, or of glass alone, or of cement and glass, or generally
of any material usually employed for resisting the action of acids and alkalies.
This vessel is divided into two compartments by means of a body of chloride of
sodium or potassium in ordinary crystalline form. This mass serves as partition
allowing the passage of the electric current but effectually separating the alkaline
liquid formed at the negative pole and the acid or chlorinised liquid which is
formed at the positive pole. This body of chloride of sodium is maintained by
plates B B of porcelain rendered very porous with large pores by incorporating
therewith substances that can either be volatilised during the baking, or be dissolved
after the baking either in water or acids.
Such very porous plates may, for example, be obtained by incorporating with
the porcelain paste carbonate of baryta in small grains, and after baking, treating
the plate with hydrochloric acid, which dissolves the carbonate of baryta.
These plates only serve as the support to the chloride powder, and they can be
replaced by plates of wood having a number of small perforations, or frames
covered with thick fabrics of pyroxilised hemp, flax or cotton.
These plates or frames terminate at a small distance from the bottom of the
bath, which is covered with a layer of chloride of sodium. They are fixed in the
side walls of the vessel below the solid parts m m which pass down to a certain
depth into the liquid, and serve as internal supports to the covers of the vessel
which are fixed thereto.
In each of the compartments thus formed is suspended an electrode C formed of
a carbon plate, by means of threaded rods d of copper which pass through the
cover of the apparatus. The parts below the cover as also their connections with
the carbon are coated with lead covered with a varnish of caoutchouc and gutta
percha. To the parts passing through the covers are attached copper bars e serving
as conductors for the electric current and for connecting the vessels either in
parallel or series. The covers must be made to close hermetically. The mode of
closing shewn on the drawing consists of screwing by means of screw bolts of the
cover, which is of wood covered with glass or slate for the positive compartments
with the interposition of strips of caoutchouc at the joints.
The middle part n is removeable for the introduction of the chloride in the form
of powder.
The hydrogen which is given off at the negative pole is drawn off by a pump of
a size proportionate to the extent of electrolytic decomposition taking place, and is
forced by the same into the pipe R which conveys it into a lead pipe S fixed below
the positive electrode and having very small perforations on its upper side, facing
the electrode, through which the hydrogen issues in a somewhat divided condition.
The hydrogen can be heated in its course before arriving in the lead pipe.
Electric arc lamps are employed for illuminating the liquid and can, if required,
be fixed in the inside of the positive compartment itself by means of an arrange-
ment similar to that of the supplemental decomposition chambers, which will be
presently described.
The hydrogen and the chlorine which are not combined in the liquid are drawn

page_text: off by a pump, the action of which is regulated by cock c according to the one first
described in order to prevent all displacement of the levels of the liquid in the two
compartments. These gases are forced into one or several small chambers made of
stone, cement or glass. These chambers Q have a strong glass tube passing
vertically through them, within which are placed the carbons of an electric arc
lamp. The hydrogen and the chlorine, which escape from the decomposing vessels
uncombined, combine in these chambers and the hydrochloric acid produced is
dissolved in the liquid of the positive compartment, which passes through the lower
part of these chambers after having been decomposed by electrolysis.
The supply tube for this liquid is provided between the chamber Q and the
positive compartment D¹ with a check valve r which may be formed of a simple
glass or caoutchouc ball. Each supply tube leading from one chamber to another
is provided with a similar valve, and the tubes for the supply of the gases have
similar valves.
The
The discharge of the electrolysed liquid is regulated by the supply, which is
effected at the bottom of the receptacle for the salts solution through the pipe M,
and this supply is itself regulated according to the intensity of the current.
alkaline solution flows off through the tube N which communicates with the
negative compartment, and it is subsequently concentrated if necessary.
Several such above described apparatus can be coupled together, and the pumps
and other accessories are so arranged as to be applicable to all.
The hydrogen gas can be taken from a source, other than that of the negative
compartment, in which case the pump would be connected to the receptacle in
which it is generated.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, we declare that what we
claim is
1. The herein described improved manufacture of caustic soda and potash and
hydrochloric acid by electrolytic treatment of chloride of sodium or chloride of
potassium.
2. In the manufacture of caustic soda and potash and hydrochloric acid referred
to in the preceding claim, the method of binding the chlorine given off at the
positive pole of the electrolytic apparatus by means of hydrogen supplied from
any source, for the production therefrom of hydrochloric acid, substantially as
described.
3. Providing the supply of hydrogen referred to in the second claim from the
hydrogen given off at the negative pole of the electrolytic apparatus, such supply
being heated if necessary for facilitating the combination, substantially as
described.
4. In the electrolytic apparatus for carrying on the process referred to in the
preceding claims the use of a body of chloride of sodium or of potassium for
separating the positive and negative compartments, substantially as described.
5. Apparatus for the electrolytic treatment of chloride of sodium or chloride of
potassium for the production of caustic soda and potash and hydrochloric acid,
arranged and operating substantially as described with reference to the drawing...
Dated this 20th day of May 1893.
ABEL & IMRAY,
Agents for the Applicants.