Improvements in Apparatus for the Electrolytical Decomposition of Salt Solutions.
Year: 1893

page_text: Date of Application, 17th Oct., 1893
Complete Specification Left. 7th Nov., 1893-Accepted, 9th Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for the Electrolytical Decomposition of
Salt Solutions.
I, CARL KELLNER, of Wasagasse 29, Vienna IX, Austria, Doctor of
Philosophy, do hereby declare the nature of this invention to be as follows:-
The apparatus hitherto proposed for the electrolytical decomposition of solutions
of salt, especially of common salt, for the production of bleaching-agents, possess
disadvantages which make it impossible to employ them successfully in practice
amongst these disadvantages being the following viz. :-they are complicated and
costly and at the same time are liable to quickly wear out; they necessitate in the
branches of industry in which they are used either entirely new plant or expensive
alterations to existing plant, viz. the addition of pipe-conduits and pumps for
connecting such plant with the electrolytic apparatus; and lastly, in apparatus
which work without diaphragms, a large portion of the current is lost, because the
nascent hydrogen reduces a portion of the already electrolytically produced
hypochlorite, and the latter, with increasing enrichment, becomes an electrolyte,
and by the formation of the hypochlorite half of the separated chlorine is
recombined into chloride.
My invention relates to apparatus whereby the above mentioned objections
are obviated. It comprises a number of conducting plates held at a suitable
distance apart by insulating rods, the whole forming what I call a "bleaching
block."
Such apparatus is simple, cheap, and durable; it can be readily and quickly
applied to any desired existing bleaching vessel in which the materials or articles
to be bleached are contained and wherein the decomposition for this purpose of the
salt-solution is to take place; and it renders practically the complete utilization of
the electric current possible, as hereinafter explained.
In the accompanying drawings,
Fig. 1 is a perspective view of an apparatus according to this invention.
Fig. 2 shows the method in which several such apparatus can be connected in
series;
Fig. 3 illustrates such apparatus arranged in an ordinary rag engine; and
Figs. 4 and 5 represent in longitudinal and in cross section respectively an
apparatus of this kind arranged for bleaching textile materials.
A, A1, A2, etc. are conducting plates, held at a suitable distance from one another
by distance tubes CCC preferably of glass, threaded on rods B B B² etc. of non-
conducting material such as hard rubber by which the plates are held together so
as to form practically one body.
The plates A A' A³ &c. are constructed by coating pieces of sheet metal, such
for example as sheet copper, tombac, or phosphor-bronze, on one side with platinum
foil and amalgamating it on the other side with mercury only.
For some purposes the plates may be of carbon or other material that is a good
conductor of electricity and is not liable to be injuriously acted upon by the
liberated ions; and the plates may sometimes be covered with a textile fabric
made of asbestos or glass-wool.
The plates A A¹ A² etc., the number of which will depend upon the potential of
the source of the current employed, are placed on the connecting rods B B' B¹
with the sides that are coated with platinum all facing in one direction, if metallic
plates of the kind referred to are used, and the first and the last plates are placed
in connection with the source of the current, the coated side of the first plate being

page_text: connected to the positive terminal, and the non-coated (amalgamated) side of the
last plate to the negative terminal.
According to the capacity and accommodation of the bleaching vessel into which
the apparatus is to be placed, the latter may consist of one block or of several
blocks arranged side by side and placed in series in such a manner that the non-
coated side of the last plate of one block is conductively connected with the coated
side of the first plate of the next block, as shown in Fig. 2; in this way the
platinum coated side of each plate serves as an anode, whilst the non-coated side of
the plates forms the cathode, where sodium is separated or caustic soda, in the
case of the decomposition of common salt is formed and hydrogen disengaged.
It will be understood that this apparatus, which, as experiments have shewn, is
not injuriously attacked, by the ions, and, in consequence of its construction,
renders attainable the production of a very large electrode-surface with a small
amount of platinum, is simply placed in the salt-solution to be decomposed, which
may advantageously be contained in the same vessel as the material or articles to
be bleached so that the formation of bleaching liquid resulting from the electro-
lytical decomposition, is effected in the presence of the substances to be
bleached.
For example, when bleaching paper-material, the salt-solution is placed in
an ordinary rag-engine D (Fig. 3) which contains the paper-material and one or
more of the herein before described apparatus is or are suspended therein, and can
be immediately put into operation by connecting it or them with the terminals of
an ordinary continuous current dynamo.
For bleaching textile fabrics, the apparatus may, as shown in Figs. 4 and 5, be
suspended in a vat E containing salt-solution and the material to be bleached be
conducted over and under rollers F, and through the solution so as to pass between
the several plates A, A', A², &c., the rods and distance tubes by which the plates
are held together being suitably arranged to enable this to be done.
The apparatus possesses the following advantages
:-
(1.) Much energy is saved, as the liberated ions come into operation in a nascent
condition.
(2.) The material being bleached itself forms a kind of diaphragm on one side
of which chlorine is liberated or formed and on the other side caustic soda, these
two substances exercising a joint dissolving or decolorizing effect, the chlorine
oxidizing the colouring substances and rendering them soluble in alkalies and
the caustic soda then dissolving them, whereupon this solution is decomposed by
the sodium hypochlorite, which is formed in excess, and sodium chloride is
reproduced.
(3.) The hydrogen being liberated at the cathode is prevented, by the material
being bleached, from reaching the anode and exerting an injurious reducing
action.
(4.) The enrichment of the electrolyte with hypochlorite and the decomposition
of this salt by the current is prevented owing to the presence of the material to
be bleached, the hypochlorite produced being re-transformed into chloride by the
bleaching process very soon after its production.
(5.) The direct formation of hypochlorite is avoided, because the material being
bleached prevents, to a certain extent, the combination of the ions.
From the foregoing description it will be seen that by means of apparatus
constructed according to this invention the bleaching operations, can be carried out
in a simple and certain manner in existing appliances, with cheap raw materials
and with a comparatively small expenditure of electrical energy.
Dated this 17th day of October 1893.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.Č., Agent for the Applicant.

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus for the Electrolytical Decomposition of
Salt Solutions.
I, CARL KELLNER, of Wasagasse 29, Vienna IX, Austria, Doctor of
Philosophy, 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 apparatus hitherto proposed for the electrolytical decomposition of solutions
of salt, especially of common salt, for the production of bleaching agents, possess
disadvantages which make it impossible to employ them successfully in practice,
amongst these disadvantages being the following, viz. they are complicated and
costly and at the same time are liable to quickly wear out; they necessitate in the
branches of industry in which they are used either entirely new plant or expensive
alterations to existing plant, viz. the addition of pipe-conduits and pumps for con-
necting such plant with the electrolytic apparatus; and, lastly in apparatus which
work without diaphragms, a large portion of the current is lost, because the nascent
hydrogen reduces a portion of the already electrolytically produced hypochlorite,
and the latter, with increasing enrichment, becomes an electrolyte and by the
formation of the hypochlorite half of the separated chlorine is recombined into
chloride.
My invention relates to apparatus whereby the. above mentioned objections are
obviated. It comprises a number of conducting plates held by insulating rods at a
suitable distance apart the whole forming what I call a bleaching block."
"
Such apparatus is simple, cheap, and durable; it can be readily and quickly
applied to any desired existing bleaching vessel in which the materials or articles
to be bleached are contained and wherein the decomposition for this purpose of the
salt-solution is to take place; and it renders practically the complete utilization of
the electric current possible as hereinafter explained.
Referring to the drawings filed with my Provisional Specification,
Fig. 1 is a perspective view of an apparatus according to this invention.
Fig. 2 shows the method in which several such apparatus can be connected in
series;
Fig. 3 illustrates such apparatus arranged in an ordinary rag-engine; and
Figs. 4 and 5 represent in longitudinal and in cross section respectively an
apparatus of this kind arranged for bleaching textile fabrics.
A, A', A2 &c. are conducting plates held at a suitable distance from one another
by distance tubes C C₁ C' preferably of glase, placed on rods B, B1, B2 &c. of
non-conducting material such as hard rubber by which the plates are held together
so as to form practically one body.
The plates A, A', A³ &c. are constructed by coating pieces of sheet metal such
for example as sheet copper, tombac, or phosphor-bronze, on one side with platinum
foil and amalgamating it on the other side with mercury only.
For some purposes the plates may be of carbon or other material that is a good
conductor of electricity and is not liable to be injuriously acted upon by the
liberated ions; and the plates may sometimes be covered with a textile fabric made
of asbestos or glass-wool.
The plates A, A', A² &c. the number of which will depend upon the potential of
the source of the current employed, are placed on the connecting rods B, B', B²;
with the sides that are coated with platinum all facing in one direction, if metallic
plates of the kind referred to are used, and the first and the last plates are placed
in connection with the source of the current, the platinum coated side of the first
plate being connected to the positive terminal and the non-coated (amalgamated)
side of the last plate to the negative terminal.

page_text: According to the capacity and accommodation of the bleaching vessel into which
the apparatus is to be placed, the latter may consist of one block or of several
blocks arranged side by side and placed in series in such a manner that the non-
coated side of the last plate of one block is conductively connected with the
platinum-coated side of the first plate of the next block, as shown in Fig. 2; in
this way the platinum-coated side of each plate serves as an anode, whilst the non-
coated side of the plates forms the cathode, where sodium is separated or caustic
soda, in the case of the decomposition of common salt, is formed and hydrogen
disengaged.
It will be understood that this apparatus, which as experiments have shewn, is
not injuriously attacked by the ions, and, in consequence of its construction, renders
attainable the production of a very large electrode-surface with a small amount of
platinum, is simply placed in the salt-solution to be decomposed, which may
advantageously be contained in the same vessel as the material or articles to be
bleached so that the formation of bleaching-liquid resulting from the electrolytical
decomposition, is effected in the presence of the substances to be bleached.
For example, when bleaching paper-pulp, the salt solution is placed in an
ordinary rag-engine D (Fig. 3) which contains the paper-pulp and one or more of
the hereinbefore described apparatus is or are suspended therein and can be
immediately put into operation by connecting it or them with the terminals of an
ordinary dynamo employed for lighting purposes.
For bleaching textile fabrics, the apparatus may, as shown in Figs. 4 and 5, be
suspended in a vat E containing salt-solution and the material to be bleached be
conducted over and under rollers F and through the solution so as to pass between
the several plates A, A1, A2 &c. the rods and distance tubes by which the plates
are held together being suitably arranged to enable this to be done.
The apparatus possesses the following advantages
-:
(1.) Much energy is saved, as the liberated ions come into operation in a nascent
condition.
(2.) The material being bleached itself forms a kind of diaphragm on one side
of which chlorine is liberated and on the other side caustic soda is formed, these
two substances exercising a joint dissolving or decolorizing effect, the chlorine
oxidizing the coloring substances and rendering them soluble in alkalies the caustic
soda then dissolving them whereupon this solution is decomposed by the sodium
hypochlorite, which is formed in excess, and sodium-chloride is reproduced.
(3.) The hydrogen being liberated at the cathode is prevented, by the material
submitted to bleaching, from reaching the anode and exerting an injurious reducing
action.
(4.) The enrichment of the electrolyte with hypochlorite and the decomposition
of this salt by the current is prevented owing to the presence of the material to be
bleached, the hypochlorite produced being re-transformed into chloride by the
bleaching process very soon after its production.
(5.) The direct formation of hypochlorite is avoided because the material being
bleached prevents, to a certain extent, the combination of the ions.
From the foregoing description it will be seen that by means of apparatus
constructed according to this invention the bleaching-operations can be carried out
in a simple and certain manner in existing appliances, with cheap raw materials and
with a comparatively small expenditure of electrical energy.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. Apparatus for the electrolytic decomposition of salt-solutions for the purpose
of producing bleaching-fluids comprising a number of plates A, A', A² of conducting
material held at a suitable distance from one another by rods of non-conducting
material and adapted to serve as electrodes when connected with an electrical
generator substantially as herein described.

page_text: 2. Apparatus of the kind specified in the preceding claim in which the
plates A, A', A' are made of sheet metal coated on one side with platinum and
amalgamated on the other side.
Dated this 7th day of November 1893.
W. LLOYD WISE,
Per F. J. Brougham,
46, Lincoln's Inn Fields, London, W.Č., Agent for the Applicant.