Improvements in the Utilization of Chlorides of Sodium and Potassium for the Obtainment of Useful Products.
Year: 1893

page_text: Date of Application, 7th Mar., 1893
Complete Specification Left, 7th Dec., 1893-Accepted, 13th Jan., . 1894
PROVISIONAL SPECIFICATION.
Improvements in the Utilization of Chlorides of Sodium and
Potassium for the Obtainment of Useful Products.
We, THOMAS PARKER, Works Director of The Electric Construction
Corporation Limited, of Wolverhampton in the County of Stafford, and ALFRED
EDWARD ROBINSON, Technical Chemist to the said Corporation, do hereby declare
the nature of this invention to be as follows:-
In the electrolysis of chloride of sodium and chloride of potassium caustic soda
and caustic potash are formed, respectively, at the negative pole, and chlorine gas
is liberated at the positive pole. The full electro-chemical efficiency of the
reaction has not heretofore been obtainable owing to the tendency of the two ions
to recombine. The object of this invention is to provide means to be employed in
connection with the said electrolysis whereby or through the medium of which the
electro-chemical efficiency is in effect increased and useful products are obtained as
hereinafter described.
This we effect by removing the caustic alkali from the sphere of electrolytic .
action by combining it with oleic, stearic, margaric, or other organic fatty acid
which in consequence of the lower specific gravity of the compound which is
thereby formed and its insolubility in the electrolyte rises to the surface in the
cathode compartment and can be removed therefrom as may be convenient.
The aforesaid acids may be added as oils or fats such as tallow, olive oil, cotton
seed oil, palm oil or the like in which the fatty acid is combined with glycerine, or
we may use the acids after they have been separated from the glycerine.
Or we may continue the electrolysis of the solution so long as an amount of
caustic soda (or caustic potash) is formed practically corresponding with the
theoretical amount obtainable for the amount of electrolytic action expended, then
remove, the solution and convert the caustic soda or potash contained therein into
the insoluble compound before mentioned, and again proceed with the electrolysis
of the chloride solution as before. The soap compound made as described may be
used as soap or for any purpose for which it is suitable, or we may treat the
compound with carbonic acid gas and thus recover from it the fatty acid and convert
the alkali into a carbonate.
Dated the 6th day of March 1893.
:
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:
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicants.
COMPLETE SPECIFICATION.
Improvements in the Utilization of Chlorides of Sodium and
Potassium for the Obtainment of Useful Products.
We, THOMAS PARKER, Works Director of The Electric Construction Company,
Limited, (formerly The Electric Construction Corporation, Limited), of Wolver-
hampton in the County of Stafford, and ALFRED EDWARD ROBINSON, Technical
Chemist to the said Company, 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 :-
In the electrolysis of chloride of sodium (common salt) and chloride of potassium,
caustic soda and caustic potash are formed, respectively, at the negative pole, and
chlorine gas is liberated at the positive pole. The full electro-chemical efficiency

page_text: of the re-action has not heretofore been obtainable owing to the tendency of the
two ions, which have been separated by the electrolytic action, to recombine. The
object of this invention is to provide means to be employed in connection with
the said electrolysis whereby or through the medium of which the electro-chemical
efficiency is in effect increased and useful products are obtained as hereinafter
described.
The above object is effected, according to this invention, by removing the caustic
alkali resulting from the electrolytic action from the sphere of such action, either
as the caustic alkali is liberated from the chlorine or from time to time before it
accumulates in sufficient quantity to interfere in a material degree with the
efficiency of the further electro-chemical reaction. The method or process of
removal from the electrolytic action consists in combining with the alkali fatty acid
such, for instance, as oleic, stearic, or margaric, either in the cathode compartment
or in a separate tank or compartment to which the solution containing the caustic
alkali has been transferred for such purpose. The compound thus formed, owing
to its lower specific gravity than the electrolyte or solution in which such compound
is formed and to its insolubility therein, rises to the surface and can be removed
therefrom by skimming or in other convenient manner.
The fatty acid may be added in the form of fat or oil such as tallow, olive oil,
cotton seed oil, palm oil or the like, as the glycerine in combination with it in such
forms does not interfere with the combination of the alkali and fatty acid and
remains neutral in the electrolyte or solution in which the combination is effected;
or the fatty acid may be used, of course, after it has been freed from any. glycerine
in combination in any convenient manner such as is now employed for the
purpose.
We prefer to remove the solution from the cathode compartment of the electrolytic
cell in which the separation of the caustic alkali from the chlorine is effected, for
the treatment thereof with fatty acid, as it avoids the liability of the porous
diaphragm of the cell becoming coated with the fatty acid and so increasing the
electrical resistance which is found to be incidental to the use of such acid in the
cathode compartment. In adopting this method of treatment the electrolysis of
the solution should, of course, be continued so long as an amount of caustic soda (or
caustic potash) is formed practically or substantially corresponding with the
theoretical amount obtainable for the amount of electric energy expended, and the
solution then be removed to a separate tank or vessel and treated with fatty acid
to convert the caustic soda (or caustic potash) into the insoluble compound before
mentioned. After the removal of the insoluble compound by skimming or other
convenient means, the solution should be returned to the cathode compartment of the
cell and the electrolysis proceeded with for the further liberation of caustic alkali;
and, when the further liberation of alkali has been carried to a point beyond which
the full electro-chemical efficiency will not be obtained if the electrolysis is continued
without the removal of some of the alkali from the sphere of electrolytic action, the
solution is again removed for treatment with fatty acid; and the alternate
processes of electrolysis and of removal of the caustic alkali are repeated as may
be required.
It is recommended to commence the process with a saturated solution of the
chloride, and to maintain the strength of the solution by the addition of chloride;
and we find the best results are obtained by using in the electrolysis a current
density of 10 to 15 amperes per square foot of positive and negative surface.
The soap compound made as described may be used as soap or for any purpose
for which it is suitable, or it may be treated with carbonic acid gas and the alkali
be thereby converted into a carbonate and the fatty acid recovered.
Having now particularly described and ascertained the nature of our said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is :-
1. In, or in connection with, the electrolysis of chloride of sodium and chloride

page_text: of potassium, the use of fatty acid to form a compound with the caustic alkali
liberated by the electrolytic action and thereby remove it from the sphere of such
action, for the purpose of ensuring the greater efficiency than would otherwise be
the case, of the further electro-chemical reaction by which further caustic alkali is.
liberated, and subsequently submitting or continuing to submit the chloride solution
to electrolytic action for the liberation of further caustic alkali, substantially as.
described.
2. In, or in connection with, the electrolysis of chloride of sodium and chloride.
of potassium, removing caustic alkali liberated by the electrolytic action from the
sphere of such action, before it has accumulated in sufficient quantity to interfere-
in a material degree with the efficiency of the further electro-chemical reaction, by
or through the medium of fatty acid, and subsequently submitting, or continuing to
submit, the chloride solution to electrolytic action for the liberation of further
caustic alkali, substantially as described.
Dated this 6th day of December 1893.
STEPHEN WATKINS,
Wolverhampton, Agent for the Applicants.