Improvements in and Apparatus for Electrolysing and Bleaching.
Year: 1891

page_text: Date of Application, 2nd Mar., 1891
Complete Specification Left, 2nd Dec., 189-Accepted, 2nd Jan., 1892
PROVISIONAL SPECIFICATION.
Improvements in and Apparatus for Electrolysing and Bleaching.
I JULIUS MARX of Bad-Nauheim in the Empire of Germany, Manufacturing
Chemist, do hereby declare the nature of this invention to be as follows :-
The object of my invention is to provide improved means for use in electrolysing
substances yielding soluble products, without the use of a diaphragm, and also for
bleaching. The apparatus, for the purposes of my present invention, may be like or
similar to, the apparatas described in the Specification of my application for Letters
Patent No. 6266 of 24th April 1890, but I do not limit myself to that apparatus;
for instance: the electrodes can be placed in the same plane instead of being one
above the other, but, if this arrangement be used, I prefer to make the electrodes
low, or but of small depth, and to prevent unchecked active communication between
anode and cathode except below and above them.
The apparatus employed is filled; for example, with an alkaline chloride and
when the electric current is passed therethrough hydrogen and chlorine develope
and the base (or caustic alkali,) remains in solution. The base and the chlorine
tend to recombine but, owing to the electrodes being low, the gas evolves quickly
and only a small part of it can recombine to form an alkaline hypochlorite. This
hypochlorite solution is exposed to carbonic acid when free hypochloric acid forms.
This liquor is electrolysed again, or repeatedly, in the same or in a series of the
apparatus.
Then the free hypochloric acid combines with the caustic alkali (alkaline base
or hydrate) set free by the action of the current and a hypochlorite is formed
and the chlorine cannot recombine except with increased difficulty and, as the ⚫
process is repeated systematically, only a small amount of hypochloric acid suffices
for the whole process as the hypochloric acid is regenerated or set free continuously
by the carbonic acid. The carbonic acid may be passed through the solution in
any convenient vessel; or the solution may be exposed to carbonic acid in a suitable
apparatus such as in a series of compartments forming an arrangement somewhat
like a staircase, or one consisting of an inclined plane with projections causing the
liquid which descends to partly rise again.
As free hypochloric acid is a known bleaching agent the process is easily adapted.
to bleaching. In this case the chlorine is caused to be absorbed more readily, and
the hypochlorite formed is redecomposed by carbonic acid the free hypochloric acid
being made to act upon the bodies, or materials, to be bleached and the solution is
preferably then re-conducted into the electrolytic and carbonating parts of the
apparatus. Thus the same liquor can be used repeatedly as the chlorine developed
by electrolysis destroys the impurities separated by the alkaline and hypochloric
acid lye and dissolved or carried along by the acting fluid.
Daied this 2nd day of March 1891.
J. H., JOHNSON & Co.,
47, Lincoln's Inn Fields, Agents.
COMPLETE SPECIFICATION.
Improvements in and Apparatus for Electrolysing and Bleaching.
I JULIUS MARX of Bad-Nauheim in the Empire of Germany Manufacturing
Chemist 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 :-
The object of my invention is to provide improved means for use in electrolysing

page_text: substances yielding soluble products (e.g. the haloid salts of the alkalies) and
also for use in bleaching. The electrolysing apparatus employed for the purposes
of my present invention is preferably without a diaphragm, and may be like, or
similar to the apparatus described in the Specification of Letters Patent No. 6266
granted to me and dated 24th April 1890, but I do not limit myself to the use of
that particular apparatus. For instance for the purposes of my present invention
as applied to bleaching I prefer the electrodes to be placed in the same horizontal
plane instead of being one above the other, and to make the electrodes low, or but
of small depth. Apparatus of greater depth can be used but then partitions are
needed or similar devices for preventing or reducing unchecked active electrical
communication between anode and cathode except below and above them. The
partition is preferably composed of porous material or according to the Specification
of Letters Patent No. 2367 granted to me and dated the 16th February 1888
allowing the transmitting of current but checking the passage of gases, but I prefer
as mentioned to employ an apparatus constructed without such partitions or
diaphragms like or similar to the arrangement described in the Specification of the
aforesaid Patent No. 6266 of 1890, and to substitute chemical action for such
mechanical separation as hereinafter explained. Although, by my shallow electrodes,
tendency to recombination is lessened, it is further reduced by the said chemical
action which is obtained with chlorides by means of hypochlorous acid, the electro-
lysing apparatus being charged with a solution of an alkaline chloride for example.
When the electric current is passed through this solution hydrogen and chlorine
are evolved and the metal or base (say caustic alkali) remains in solution. The
base or hydrate and the chlorine tend to recombine, but owing to the electrodes.
being low, the gas has to traverse but little liquid, therefore it escapes so quickly
that only a small part of the chlorine can recombine with the base to form an
alkaline hypochlorite. By suction this favourable condition may be further
enhanced.
This is a great advantage obtained by my improved arrangement of the electro-
lys ng apparatus as described in the Specification of the aforesaid Patent No. 6266°
but the process can be further improved by causing an acid to act which prevents
or reduces the objectionable influence of the chlorine but which acid can be readily
removed afterwards.
The purpose of this operation being to provide a weak acid, which is able to take
up the alkali liberated by the electrolysis and to protect it thus more or less against
the chlorine.
At the same time this acid must be readily removeable afterwards because of the
object of the process, namely, to obtain the alkali.
A very convenient plan for effecting this is expose this hypochlorite solution to
the action of carbonic acid which has the effect of forming free hypochlorous acid.
By these means the liquor is caused to contain according to the quantity of carbonic
aed employed, a mixture of free hypochlorous acid and alkaline carbonates, or
.bicarbonates. This mixture is then again subjected to electrolysis in the same, or in
another apparatus wherein the alkali (alkaline base or hydrate) is formed anew by
the el ctrolytic action and forms a hypochlorite by combination with the free
hypochlorous acid produced as afore said. In this case the liquor is caused to
contain a mixture of alkaline carbonates and hypochlorites and the chlorine not
finding free alk ili to act upon separates more easily as its tendency to recombine is
reduced.
The process is repeate·l methodically that is to say the liquor which has been
subjected to ele trolysis is immediately treated with carbonic acid and then again
subjected to the electric current the same liquid being caused to circulate con-
tinuously through the series of apparatus and being regenerated as required by the
introduction of a fresh supply of the salt. Obviously it is possible to separate the
electrolysing and carbonating operations but this method would not be economical
in practice. By combining the action of the carbonic acid and of the electric'
current as hereinb fore described a constant and systematic repetition of the

page_text: operations, namely of obtaining or separating chlorine, alkali and hypochlorous
acid, is ensured. A small amount of hypochlorous acid is sufficient for the purpose
of the operation as this agent is continually regenerated or set free by the action of
the carbonic acid. The resulting chlorine and carbonates are employed as usual to
make chlorates, hypochlorites, bleaching powder, and the like, or soda, potash,
alkaline bicarbonates and the like.
The carbonic acid may be passed through or brought into contact with the
solution in any convenient manner for instance by introducing the carbonic acid
directly into the electrolysing vessel or by means of a separate apparatus of any
suitable construction.
An apparatus which I have found very convenient for providing the hypochlorous
acid in practice is constructed with an inclined plane having transverse ribs or
projections which impede or break up the stream of liquid admitted from the
electrolysing apparatus to the upper end of the inclined plane and cause currents or
small eddies to be formed in the body of the liquid in such a manner as to bring
every part thereof up to the surface and so into contact with the carbonic acid
which is supplied to a chamber or enclosed space above the liquid flowing over the
inclined plane.
A suitable form of this apparatus is represented in vertical section in the annexed
drawing. The electrolytic tank or vessel is combined with the apparatus shown so
that the electrolysed liquor enters it by the tube o and passes into the stand pipe >>'
(preferably open at both ends) and passes therefrom into the troughs and when
this is filled the liquor overflows the edge thereof and passes down the inclined
plane into the troughs which it leaves by the tube and passes therethrough
into the next electrolysing apparatus or into any other place where it is to be
further treated or utilized.
1
The inclined plane u is provided at intervals with transverse ribs or projections u u¹
causing the liquid to rise and fall constantly as it runs down the inclined plane thus
bringing about a continuous renewal of its surface. The apparatus is covered with a
lid or cover provided with the tubes and through which the carbonic acid is
admitted to above the liquor flowing down the incline plane. The troughs and st
form hydraulic seals and prevent the carbonic acid passing out through the pipes of
and n.
0
The carbonic acid by combination with the alkali as before mentioned forms
carbonate and hypochlorous acid is liberated by decomposition of the hypochlorite.
If an excess of carbonic acid be used the liquid is caused to contain carbonates,
carbonic acid and hypochlorous acid together with such chloride as may have
escaped decomposition and which may be supplemented by a fresh supply of chloride
before the liquid flows into the next electrolysing apparatus. In this apparatus the
electrolytic decomposition of the chloride produces a fresh quantity of alkaline
hydrate which combines with the free acid, at the same time the presence of the free,
acid facilitates the developement or separation of the alkali.
As free hypochlorous acid is a valuable bleaching agent the process is well
adapted for bleaching purposes. In this case the absorption of the chlorine requires
to be accelerated.
This is done by causing the carbonic acid to act on the solution in a lesser degree
during the electrolytic action. If weak solutions only are required the carbonic
acid may even be dispensed with but for strong solutions the chlorine obtained is
caused afterwards to act upon the alkaline solution resulting from the aforesaid
treatment to make it stronger. Thus the liquor can be made to contain any desired
relative proportions of hypochlorous acid, hypochlorite, carbonic acid and free
alkali. In the first instance as hereinbefore described an alkaline hypochlorite is
formed by the action of the electric current (or of the chlorine) but it is decomposed
by the carbonic acid and hypochlorous acid is set free, which is caused to act upon
the material to be bleached either more or less combined or as free acid made by
treating the bleaching liquor with sufficient carbonic acid before or during the
bleaching operation.

page_text: After bleaching the solution is preferably reconducted into the electrolytic and
carbonating parts of the apparatus. Thus the same liquor can be used repeatedly
as the chlorine developed by the electrolysis destroys most impurities that may be
separated by the alkaline and hypochlorous acid lye and dissolved or carried along
in the liquid.
Of course fresh chloride must be added to the solution in order to regenerate the
same when necessary
By conducting the process as hereinbefore described the hypochlorous acid is
caused to do that part of the work of the diaphragms which is essential in electro-
lysing alkaline compounds, that is to say it prevents or reduces the reabsorption or
recombination of the electrolytic products, for example of the alkali with the free
halogen, and enables me to improve still further upon my electrolysing and precipi-
tating processes described in my aforesaid Specifications and in the Specification
of Letters Patent No. 6417 of 2nd May 1887.
It will be well understood by electro-chemists that acids which act similarly can
be used instead of hypochlorous acid and that heating or cooling can be employed
as circumstances require.
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. In the electrolysis of the haloid salts of the alkalies more especially of the
chlorides for making carbonates for bleaching or other purposes the use of carbonic
acid to develop active hypochlorous acid from hypochlorites and the use of hypo-
chlorous acid and acids which act similarly substantially as and for the purpose
herein before described.
2. The treatment of electrolized solutions of haloid salts of the alkalies by
means of carbonic acid caused to come into contact with the said solutions as they
pass from the electrolizing apparatus for the purpose of causing the action of
hypochlorous acid in the manner substantially as hereinbefore described.
3. In electrolizing solutions of haloid salts of the alkalies the process consisting
in exposing the electrolysed liquids proceeding from both electrodes to the action
of carbonic acid so that the alkali contained in the liquid is carbonated and hypo-
chlorous acid is set free which absorbs the free alkali formed in the next electrolytic
vessel and thus further reduces the combination of the chlorine or halogen substan-
tially as hereinbefore described.
4. For treating electrolized solutions of haloid salts of the alkalies for bleaching
or other purposes with carbonic acid as herein before described and claimed an
apparatus constructed with an inclined plane provided with ribs or projections
which impede the flow of the solution and produce currents circulating in the body
of the solution so as to bring the said solution into efficient contact with the carbonic
acid in combination with means for admitting the liquid to and discharging it from
the apparatus and for admitting carbonic acid all substantially as and for the
purpose hereinbefore described and illustrated in the accompanying drawings.
Dated this 2nd day of December 1891.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.