Improvements in the Manufacture or Production of Chlorine and Alkaline Carbonates.
Year: 1891

page_text: Date of Application, 27th Nov., 1891
Complete Specification Left, 28th Dec., 1891-Accepted, 20th Feb., 1892
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture or Production of Chlorine and
Alkaline Carbonates.
1, Carl Kellner, Director of the Kellner-Partington-Paper-Pulp‐Company,
Limited, IX Wasagasse 29, Vienna, Austria, do hereby declare the nature of this
nvention to be as follows:-
If in the electrolytical decomposition of haloid alkaline salts, easily soluble com-
pounds are formed and allowed to accumulate, such compounds will be again and
gain decomposed by the electric current, thereby causing a loss of electric power.
Laboratory experiments made in 1889 furnished means for obviating this incon-
In these
venience by facilitating the formation of compounds not easily soluble.
experiments departing from the known fact that mono-carbonate of soda is not
easily soluble in a saturated solution of chloride of sodium, the latter has been
decomposed into chlorine and sodium, carbonic acid being at the same time
introduced into the space containing the cathodes thus causing the formation of a
precipitate of carbonate of soda, whilst the chlorine set free escaped from the
space occupied by the anodes to which space was constantly added fresh quantities
of solid chloride of sodium.
This invention has for its object to afford the possibility of attaining industrially
the results arrived at in the aforesaid experiments, that is to say to enable the
liberation of great quantities of chlorine under the simultaneous production of an
alkaline carbonate. The fundamental conditions of industrial production are
continuity and cheapness, and the process carried out in the experiments has been
correspondingly developed. In order to insure a continuous working, it was first
of all necessary to prevent the formation of the alkaline carbonate taking place
inside the electrolysing apparatus as, otherwise, the operation would have to be
unavoidably interrupted from time to time to dismount the apparatus in order to
remove the products. Further, it has been necessary to effect the largest possible
yield of valuable products with the least possible expenditure of electric current,
or motive power; consequently it was necessary, that in the first place, the
electrolyte coming from the electrolyzer and not entirely decomposed should be
conveyed back for further treatment, and, in the second place, that the precipitation
of the alkaline carbonate should take place under conditions insuring the maximum
yield of carbonate which could only be effected by constantly keeping the solution
coming from the space within which the cathodes are contained, and carrying with
it the caustic alkali, in a saturated condition, as the solubility of the alkaline
carbonates in their haloid solutions increases in the same proportion as these
solutions are more diluted.
The discovery of an industrial process furnishing means for obtaining at the
same time chlorine and alkalies has been all the more desirable because all the
methods of electrolytical decomposition hitherto proposed possess some very serious
inconveniences oz. :-
(1) The formation in the electrolyzer, besides chlorine and alkali, of a hypo-
chlorite which is afterwards decomposed again and again by the current, during
the further decomposing operation.
2. The impurity of the products obtained.
3. The rapid wearing out of the anodes and of the diaphragms.
4. The diffusion of the hydrogen set free.
The process hereinafter described obviates these defects in the following
manner-The electrolyte kept constantly in a saturated state, is admitted to the
electrolyzer and caused to flow past the electrodes with such rapidity that but a

page_text: very small part of it is decomposed into ions, which are not removed from the
solution until they have passed out of the apparatus. This apparatus comprises
electrodes arranged in cells separated by diaphragms made as hereinafter described
the hydrogen set free being removed by continuous suction.
In the apparatus hitherto in use, the decomposition of a haloid alkaline salt,
for instance of common salt into chlorine and caustic soda, takes place without any
hindrance at the beginning of the operation; but as soon as the liquid surrounding
the cathodes contains a certain proportion of caustic soda, the latter begins to
diffuse towards the space containing the anodes, there to form a hypochlorite
which is afterwards decomposed by the current and reduced by the hydrogen, also
diffusing from the cathode, in such a manner that a chlorate, a haloid salt, and
water, are simultaneously formed.
In the bleaching process for which I have obtained Letters Patent dated
5th April 1890 No. 5285, I have obviated this inconvenience by causing the ions
to circulate constantly through the bleaching vats and by not conveying them back
to the electrolyzer until, under the action of the décomposed organic coloring
matters all the active chlorine contained in the solution has been converted into
hydrochloric acid, and the two ions, in meeting again, have reconstituted the
original electrolyte (Na Cl).
The principle upon which the invention referred to is based, has been developed
with the aforesaid object of simultaneously obtaining chlorine and an alkali. The
saturated solution of the electrolyte (common salt, for instance) flows through the
electrolyzer with a great velocity; after leaving the apparatus, the substances set
free are removed from the solution; and the liquid fed into the decomposing cells
is always kept saturated by constantly adding to it fresh quantities of the salt to
be decomposed. The substances set free by the action of the electric current are
removed from the solution, the chlorine being removed by suction and eventually
combined with lime or otherwise dealt with, and carbonate of soda being precipitated,
whilst the solution carrying with it the caustic soda is maintained in a saturated
state, by bringing it constantly in contact with solid chloride of sodium in such
a manner that when the said solution is cooled and carbonic acid is blown into it,
the carbonate of soda thus formed will be precipitated. By this means the forma-
tion of hypochlorite and of chlorate is almost completely prevented and thus the
principal defect of the processes heretofore proposed is obviated.
In all the methods hitherto suggested for attaining the above mentioned result,
there arises the necessity of separating from the alkaline products formed in the
electrolyzer, the chloride of sodium which might have become mixed with them in
consequence of incomplete decomposition or of diffusion. This inconvenience is
also remedied by my invention, as the carbonate of soda which crystallizes outside
of the decomposing apparatus, is nearly chemically pure and requires no further
purifying treatment.
As to the rapid wearing out, after a short time, of the anodes and diaphragms,
which I have pointed out as being the third inconvenience of the methods hitherto
suggested, I meet it by making the anodes and diaphragms of a particular com-
position the effect of which is to render their power of endurance completely
independent of the decomposing operation.
The anodes employed in the carrying out of my process are made in the
following manner; wood-fibre or cellulose is dissolved in a concentrated solution of
chloride of zinc, and the liquid if caused to evaporate in a vacuum apparatus until
it has attained a syrup-like consistence; then powdered-retort carbon (graphite) is
added to it and the whole is kneaded in a kneading machine into a thick paste.
This paste is formed under strong pressure, into rods or slabs, which are dried and
then washed in water until the whole of the zinc chloride is eliminated.
These rods or slabs are afterwards impregnated several times with heavy
hydrocarbon, and heated in inuffles filled with coal-dust. When the desired hard-
ness and density have been obtained, they are plunged into a solution of a salt of
lead which may advantageously be acetate of lead, dried and then inserted, first

page_text: as cathodes, and afterwards as anodes, into a bath of dilute sulphuric acid. By
this means the lead salt is reduced, the lead being deposited in its metallic state
within the pores of the material, and being afterwards transformed into peroxide.
The same result might be attained by covering the carbon electrodes with a layer
of litharge mixed with sulphate of ammonia.
The electrodes prepared in the manner described are either placed directly into
the electrolizer, or they may be first heated in paraffin, or in a solution of water
glass at about 38° Be., until no more air bubbles are evolved, and then dipped in
muriatic acid.
A large number of experiments made on a great variety of diaphragms have led
me to the conclusion that for carrying out my process on a large scale the most
suitable diaphragms are those which have their pores filled with some gelatinous
material, in such a manner that the electric diffusion (circulation of the ions) is
free to take place under the action of the current whilst the mechanical diffusion
of the several substances formed is prevented. The diaphragms which have
found most suitable for this purpose are made of wood fibre or cellulose dipped
in a solution of water glass, and after being impregnated with the same, plunged
in muriatic acid so as to have their pores filled up with silicic acid in a gelatinous
state. The best way of afterwards using these diaphragms is to insert them
between two sieves having large meshes, one of which, turned towards the anodes,
is of horsehair, and the other, turned towards the cathodes, is of wire. As a
substitute for cellulose, some woven fabric, arranged in several layers, may be used,
although for the sake of uniformity, I prefer a sheet of thick paper.
In the same
manner, ordinary diaphragms of porous clay may also be employed in carrying out
my process, provided that they have been boiled in a solution of water glass
until no more air bubbles are driven off, and have then been plunged into muriatic
acid.
The sodium chloride, which is formed by the action of the muriatic acid on
the silicate of soda, is mixed in such a manner with the particles of the gelatinous
silicic acid lying in the pores of the diaphragm, that the conductibility of the
diaphragm prepared as above described so as to admit of the circulation of the
ious, is most satisfactory, whilst, on the other hand, the alkali formed at the cathode
cannot diffuse towards the anode, there to form a hypochlorite, as silicic acid with
which the pores of the diaphragm are filled, prevents its passage through the
diaphragm.
If in certain cases fears were entertained that the cation, when evolved in excess,
might attack the gelatinous silicic acid in the diaphragm, it is obvious that the
pores of the latter may be filled with some other gelatinous substance, such for
examples as hydrate of aluminium, glue, albumen or starch, not readily attacked
by the cation, without departing from the principle of my invention, which consists
in preventing the ions set free from diffusing and consequently disturbing the
electrolytical decomposition, and in filling, for that purpose, the pores of the
diaphragms placed between the electrodes with some gelatinous material which,
coming in contact with a solution of a good conductor, will have no disturbing
action on the circulation of the ions as determined by the current.
Finally the fourth defect hereinbefore mentioned, .e. the diffusion of the
hydrogen, is totally suppressed, as the hydrogen set free at the cathodes is drawn
out of the electrolizer by suction. The removal of the hydrogen in this way may
be assisted by injecting a blast of carbonic acid into the cathode cells; but in
that case, due precautions must be taken to keep the temperature of the electrolyte
as high as is necessary for preventing the carbonate formed from settling within
the apparatus.
When the hydrogen escapes from the apparatus, it is advisable to force it through
a light hydrocarbon, and then to store it in a gasometer whence the gas thus
carburetted may be fed to heating or illuminating appliances.
Having described the chief features of my invention, and the detailed phases it

page_text: comprises, I will now explain fully the working of my process it being supposed
that a saturated solution of chloride of sodium is used as an electrolyte.
In the accompanying drawings,
Fig. 1 is a diagrammatic illustration of apparatus for carrying out my invention.
A and B are two vats, which at the beginning of the operation are filled with a
saturated solution of the salt to be used as. an electrolyte-common salt in the
present case and in which are suspended baskets and containing solid
chloride of sodium intended to maintain the solution in a saturated state. These
baskets can be replaced by any other appliance that will admit of the liquid being
constantly in contact with the solid salt.
One of the vats, (A), communicates by means of a pipe with the first cell of
the cathodes, and the other vat, (B), communicates by means of a pipe with the
first cell of the anodes, these electrodes belonging to an electrolizer C consisting of
a series of separate frames connected together in the same manner as those of a
filter-press.
Fig. 1 shews the electrolizer partly in vertical longitudinal section and partly
side elevation; and
whilst the
Fig. 2 shews it partly in horizontal section and partly in plan or top view.
Figs. 3 and 4 illustrate two of the frames forming part of the electrolizer.
As shewn the electrode cells 1, 2, 3, 4. . formed by and between the
frames R and the diaphragms D, are connected one with the other in such a
.manner that the electrolyte admitted into the apparatus by the pipe F1 (1, in
Fig. 1) necessarily passes through all the anode cells 1, 3, 5. .
electrolyte fed from pipe F2 ( in Fig. 1) passes through all the cathode cells 2,
4, 6.
It is advisable to cause these liquid streams, when within the electrode
cells. to flow across them diagonally in an upward or downward direction, which is
effected by providing for each upper admission port cut in one of the standards of
the frame, a lower outlet port cut in the opposite standard of the same frame. For
the sake of clearness I shall describe the path followed by the stream of liquid
electrolyte passing from pipe F into the anode cell 1. The stream enters this cell
through port o' in the left top corner (Fig. 3), flows out through o² in the right
bottom corner, passes through the passage cut in the right bottom corner of the
frame of cell 2, and flows through in the right. bottom corner of cell 3, and
through this cell which it leaves by the port of in the left top corner;
passes through the opening o cut in the left top corner of cell 4 (Fig. 4) then into
cell through port o³ in the left top corner, and escapes at of in the right bottom
corner and so on.
it then
In the same manner, the electrolyte supplied from pipe F2 is introduced into the
first cathode cell through port a in the right top corner, leaves it through a² in the
left bottom corner, crosses the frame of cell 3 through the aperture provided in
the left bottom corner of the same, enters through a (Fig. 4) the left bottom
corner of cell 4, and so on. The pipes F F for supplying the electrolyte to the
apparatus may have cocks for the purpose of regulating the discharge.
The electrodes E may advantageously be in the form of cylindrical or prismatical
rods with fluted surfaces. The cathodes may be of iron. The anodes may be made
in the manner hereinbefore described.
The ions set free in the apparatus escape through the pipes G¹ G².
In order that the gases set free during the decomposing operation should be
allowed to escape separately, the frames R have holes g therethrough forming a
continuous passage placed above the upper lateral communicating passages, and
.these holes are connected with the passages o . . . and a cut in the upper
part of the framing and through which flows the electrolyte, by means of
passages respectively. In consequence of the slope given to the underside of
the top of each frame R (as shewn in Eigs. 3 and 4) the cells have their roofs
inclined alternately to the right and to the left, this arrangement facilitating the
escape of the gases into the passages through which the electrolyte passes, as above

page_text: ני
explained from one cell into the next cell but onc. The gases consequently flow
with the electrolyte into the passages o . . . and a. . . . whence they rise
through the small pipes into the passages g g'. The gases thus separated from
the liquids, flow out of the apparatus through the separate pipe attachments i i
provided on the front plate Ri and through pipes jj'. The chlorine and hydrogen
evolved at the anodes and cathodes respectively are thus perfectly separated from
each other, and are conveyed through the pipes (Fig. 1) to any desired place.
If it be desired to blow a gas into the apparatus, this can be easily effected by
means of a pipe formed of successive passages g³ cut in the bottom members of the
frames R. Slots are provided in the floor of those cells into which it is intended
to introduce the gas, and, as these slots reach downwards as far as the passages g³,
they allow gas to enter the respective cells from these passages. A pipe serves
to convey the gas to the conduit thus formed by the successive passages.
In the drawings these slots for the admission of gases are cut in the floor of the
cathode cells; they may be used either for blowing in air in order to remove
hydrogen from the electrodes and to prevent its depolarizing action, or carbonic
acid for the purpose of neutralizing the caustic alkalies formed.
The heating of the electrolyte is carried out either in the vats A and B or in the
electrolizer or simultaneously in each of these vessels.
When leaving the decomposing apparatus C, which is arranged with its axis
inclined so as to facilitate the escape of the gases, the liquids, viz. the solution of
sodium chloride coming from the anodes, and the solution of sodium chloride
containing caustic soda coming from the cathodes, are conveyed through the pipe
attachments GG² (Fig. 2) respectively and the pipes g, g' (Fig. 1) into vats M
and N.
The vat M which receives the solution of sodium chloride coming from the
anodes and which always contains some chlorine, is closed, and has a pipe 2 which
may convey the chlorine into the same vessel as that into which the chlorine set
free in the electrolizer C is conveyed by the pipe ». A steam worm d, made of
lead, with closed or perforated walls,. is placed on the bottom of the vat M and
serves for heating the liquid therein. This heating operation can also be effected
while the liquid is being conveyed into the vat B, by using a steam jet apparatus
or injector of lead instead of the pump p. The solution of electrolyte from the
vat M is forced by the pump through the pipe into the vat B which is also
closed, and connected by a pipe with the gas holder, as chlorine is also set free
in appreciable quantities in the vat B owing to solid sodium chloride from the
basket being continually dissolved.
The vat N into which is conveyed the solution of electrolyte coming from the
cathodes and containing caustic soda, comprises, besides special cooling appliances, a
metallic perforated pipe e into which a compressor or a forcing pump F blows
carbonic acid taken from any suitable source, but preferably sucked from the kilns
in which is burned the lime which is to be combined with the liberated chlorine.
A basket suspended in the liquid in vat N holds sodium chloride in a solid state.
A. stirring device e' may be arranged in the vat N in order to ensure the thorough
mixture of the liquids therein, and to prevent the settling of large crystals of
carbonate of soda. As the liquid is always kept at its highest point of con-
centration, since it passes through the basket k² containing solid sodium chloride,
and as the carbonate of soda is very difficult to dissolve in a saturated solution of
sodium-chloride, the carbonate of soda is precipitated in the form of small crystals.
After leaving the vat N the solution is conveyed by the pipe either into settling
or decanting vessels. P and P', or into a filter of known construction, whence it
passes to a pump pl. Or the solution may be forced through a filter press Q by a
pump and raised into the vat A, which it again leaves in order to again undergo
the successive treatment. hereinbefore set forth. The pipes used in the latter
case are marked in the figures in dotted lines.
The crystallized carbonate of soda collected in the filter press or in the decanting
vessels is dried in a hydro-extractor, covered with water or with a saturated

page_text: solution of soda, and may then be sold as crystallized carbonate of soda. The
chlorine carried away by pipe may be conveyed into chambers containing
powdered hydrate of lime and be thus converted into chloride of lime or bleaching
powder it may also be used for other purposes.
From the foregoing description it will be understood that my process provides
means for directly obtaining pure crystallized carbonate of soda by precipitation
from the solution coming from the cathodes, and that consequently it is no longer
necessary, as was the case in other methods hitherto proposed to perform a distinct
operation for transforming the bicarbonate of soda into mono-carbonate. Since the
electrolyte after having been deprived of the alkali therein contained, is completely
saturated again in the vat. N before being conveyed back into the vat A, the
basket suspended in the latter vat for holding solid chloride of sodium may be
dispensed with according to circumstances.
As will be understood, the solution fed into the decomposing apparatus is
maintained constant in quantity, and always in a saturated condition, and it
circulates through the apparatus with such a velocity that the electrolyte in
contact with the electrodes can only retain a very small portion of the ions set free,
which are afterwards eliminated from the solution outside of the decomposing
apparatus.
It is very advantageous to heat the solution by preference in the vats A and B,
as by this means the conductivity of the solution is increased and maintained, the
evolution of the chlorine set free at the anodes is accelerated, and the settling of
crystals of carbonate of soda at the cathodes is prevented. The settling of these
crystals in the vat N is on the other hand facilitated by cooling the liquid contained
in this vat.
As in the process described in my said former Specification, so in the process
hereinbefore described, the solution of electrolyte, whilst in the electroliser, contains
but a very small quantity of the ions, in consequence of which all disturbing
influences are avoided and at the same time, the depolarization being lessened, a
saving is effected in the motive power required.
If it be desired to manufacture only bleaching agents in small quantities for use
in some industrial establishment, such as bleaching or paper works, the intro-
duction of carbonic acid into the solution which has circulated past the cathodes,
for the purpose of forming a precipitate of carbonate of soda may be dispensed
with. In this case, the liquid will preferably consist of a solution of chloride of
sodium and of caustic soda, and, when coming from the cathodes, it will be raised
directly into vat A, where it will dissolve sodium chloride until saturated, after
which it will again circulate through the cathode cells, absorb caustic soda, and
again rise into A, there to dissolve sodium chloride, these operations being repeated
in a continuous manner. It is advisable in this case, to supply the anodes with a
saturated and heated solution of sodium chloride, to which sulphuric acid has been
added. A slight addition of sulphuric acid, up to 0.5% to the electrolyte which
comes in contact with the anodes, is, in fact, advisable in all cases, as the resulting
sulphate of soda which remains in the liquid whilst it circulates has a decomposing
action on the hypochlorites and the chlorates present therein and the formation of
which cannot be entirely avoided. A sulphate of the alkali used may be added
instead of sulphuric acid if desired.
Dated this 27th day of November 1801

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture or Production of Chlorine and
Alkaline Carbonates.
I, CARL KELLNER, Director of the Kellner-Partington-Paper-Pulp-Company-
Limited, IX Wasagasse 29 Vienna, Austria, 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 :-
If in the electrolytical decomposition of haloid alkaline salts, easily soluble
compounds are formed and allowed to accumulate, such compounds will be again
and again decomposed by the electric current thereby causing a loss of electric
power. Laboratory experiments made in 1889 furnished means for obviating this
inconvenience by facilitating the formation of compounds not easily soluble. In
these experiments starting from the known fact that mono-carbonate of soda is not
easily soluble in a saturated solution of chloride of sodium, the latter has been
decomposed into chlorine and sodium, carbonic acid being at the same time
introduced into the space containing the cathodes thus causing the formation of a
precipitate of carbonate of soda, whilst the chlorine set free escaped from the space
occupied by the anodes to which space was constantly added fresh quantities of
solid chloride of sodium.
This invention has for its object to afford the possibility of attaining industrially
the results arrived at in the aforesaid experiments, that is to say, to enable the
liberation of great quantities of chlorine with the simultaneous production of an
alkaline carbonate. The fundamental conditions of industrial production are
continuity and cheapness, and the process carried out in the experiments has been
correspondingly developed. In order to insure a continuous working, it was first
of all necessary to prevent the formation of the alkaline carbonate taking place
inside the electrolysing apparatus, as, otherwise, the operation would have to be
unavoidably interrupted from time to time to dismount the apparatus in order to
remove the products. Further, it has been necessary to effect the largest possible
yield, of valuable products with the least possible expenditure of electric current,
or motive power; consequently it has been necessary, in the first place, that the
electrolyte coming from the electrolyzer and not entirely decomposed, should be
conveyed back for further treatment; and, in the second place, that the precipitation
of the alkaline carbonate should take place under conditions insuring the maximum
yield of carbonate which could only be effected by constantly keeping the solution
coming from the space within which the cathodes are contained, and carrying with
it the caustic alkali, in a saturated condition, as the solubility of the alkaline
carbonates in their haloid solutions increases in the same proportion as these
solutions are more diluted.
The discovery of an industrial process furnishing means for obtaining at the
same time chlorine and alkalies has been all the more desirable because all the
methods of electrolytical decomposition hitherto proposed possess some very serious
inconveniences viz. :-
(1) The formation in the electrolyzer, besides chlorine and alkali, of a hypo-
chlorite which is afterwards decomposed again and again by the current, during the
further decomposing operation.
2. The impurity of the products obtained.
3. The rapid wearing out of the anodes and of the diaphragms.
4. The diffusion of the hydrogen set free.
The process hereinafter described obviates these defects in the following
10anner :- -The electrolyte kept constantly in a saturated state, is admitted to the
electrolyzer and caused to flow past the electrodes with such rapidity that but a
very small part of it is decomposed into ions, which are not removed from the
solution until they have passed out of the apparatus. This apparatus comprises

page_text: anodes arranged in cells separated by diaphragms made as hereinafter described,
the hydrogen set free being removed by continuous suction.
In the apparatus hitherto in use, the decomposition of a haloid alkaline salt, for
instance common salt, into chlorine and caustic soda, takes place without any
hindrance at the beginning of the operation; but as soon as the liquid surrounding
the cathodes contains a certain proportion of caustic soda, the latter begins to
diffuse towards the space containing the anodes, there to form a hypochlorite which
is afterwards decomposed by the current and reduced by the hydrogen, also diffusing
from the cathode, in such a manner that a chlorate, a haloid salt, and water, are
simultaneously formed.
In the bleaching process for which I have obtained Letters Patent dated
5th April 1890 No. 5285, I have obviated this inconvenience by causing the ions
to circulate constantly through the bleaching vats and by not conveying them back
to the electrolyzer until, under the action of the decomposed organic coloring
matters, all the active chlorine contained in the solution has been converted into
hydrochloric acid, and the two ions, in meeting again, have reconstituted the
original electrolyte (Na Cl).
The principle upon which the invention referred to is based, has been developed
with the aforesaid object of simultaneously obtaining chlorine and an alkali. The
saturated solution of the electrolyte (common salt, for instance) flows through the
electrolyzer with a great velocity; after leaving the apparatus, the substances set
free are removed from the solution; and the liquid fed into the decomposing cells
is always kept saturated by constantly adding to it fresh quantities of the salt to
be decomposed. The substances set free by the action of the electric current are
removed from the solution, the chlorine being removed by suction and eventually
combined with lime or otherwise dealt with, and the crystallized carbonate of soda
being precipitated, whilst the solution carrying with it the caustic soda is maintained
in a saturated state, by bringing it constantly in contact with solid chloride of
sodium in such a manner that when the said solution is cooled and carbonic acid is
blown into it, the crystallized carbonate of soda thus formed will be precipitated.
By this means the formation of bypochlorite and of chlorate. is almost completely
prevented and thus the principal defect of the processes heretofore proposed is
obviated.
In all the methods hitherto suggested for attaining the above mentioned result,
there arises the necessity of separating from the alkaline products formed in the
electrolyzer, the chloride of sodium which might have become mixed with them.in
consequence of incomplete decomposition or of diffusion. This inconvenience is
also remedied by my invention, as the carbonate of soda which crystallizes outside
of the decomposing.apparatus is nearly chemically pure and requires no further
purifying treatment.
As to the rapid wearing out, after a short time, of the anodes and diaphragms,
which I have pointed out as being the third inconvenience of the methods hitherto
suggested, I meet it by making the anodes and diaphragms of a particular
composition the effect of which is to render their power of endurance completely
independent of the decomposing operation.
The anodes employed in the carrying out of my process are made in the
following manner :- -Wood cellulose is dissolved in a concentrated solution of
chloride of zinc, and the liquid is caused to evaporate in a vacuum apparatus
until it has attained a syrup like consistence; then powdered retort carbon
(graphite) is added to it and the whole is kneaded in a kneading machine into a
thick paste.
This paste is formed under strong pressure into rods or slabs which
are dried and then washed in water until the whole of the zinc chloride is
eliminated.
These rods or slabs are afterwards impregnated several times with heavy hydro-
carbon, and heated in muffles filled with coal dust. When the desired hardness
and density have been obtained, they are boiled in a solution of a salt of lead which
may advantageously be of acetate of lead, dried and then-inserted, first as cathodes,

page_text: and afterwards as anodes, into a bath of dilute sulphuric acid. By this means the
lead salt is first reduced, the lead being deposited in its metallic state within the
pores of the material, and being afterwards transformed into peroxide. Or
the same result might be attained by first covering the carbon electrodes with a
layer of litharge mixed with sulphate of ammonia, and then subjecting them to a
similar electrolytical treatment.
The electrodes prepared in the manner described are either placed directly into
the electrolyzer, or they may be first heated in paraffin, or in a solution of water
glass at about 38° Be., until no more air bubbles are evolved, and then dipped in
muriatic acid.
A large number of experiments made on great variety of diaphragms have
led me to the conclusion that for carrying out my process on a large scale the
most suitable diaphragms are those which have their pores filled with some
gelatinous material in such a manner that the electric diffusion (circulation of
the ions) is free to take place under the action of the current whilst the mechanical
diffusion of the several substances formed is prevented. The diaphragms which I
have found most suitable for this purpose are made of wood-cellulose dipped in a
solution of water glass, and after being impregnated with the same, plunged in
muriatic acid so as to have their pores filled with silicic acid in a gelatinous state.
The best way of afterwards using these diaphragms is to insert them between two
sieves having large meshes one of which, turn towards the anodes, is of horsehair,
and the other, turned towards the cathodes, is of wire. As a substitute for wood-
cellulose, some woven fabric, arranged in several layers, may be used, although for
the sake of uniformity, I prefer a sheet of thick paper.
In the same manner
ordinary diaphragms of porous clay may also be employed in carrying out my
process, provided that they have been boiled in a solution of water glass until no
more air bubbles are driven off, and have then been plunged into muriatic acid.
The sodium chloride, which is formed by the action of the muriatic acid on the
silicate of soda, is mixed in such a manner with the particles of the gelatinous
silicic acid lying in the pores of the diaphragm, that the conductibility of the
diaphragm prepared as above described so as to admit of the circulation of the
ions, is most satisfactory, whilst, on the other hand, the alkali formed at the cathode
cannot diffuse towards the anode, there to form a hypochlorite, as the silicic acid
with which the pores of the diaphragm are filled, prevents its passage through the
diaphragm.
If in certain cases fears should be entertained that the cation when involved in
excess, might attack the gelatinous silicic acid in the diaphragm, it is obvious that
the pores of the latter may be filled with some other gelatinous substance, such for
examples as hydrate of aluminium, glue,-albumen, or starch, not readily attacked
by the cation, without departing from the principle of my invention, which consists
in preventing the ions set free from diffusing and consequently disturbing the
electrolytical decomposition, and in filling, for that purpose, the pores of the
diaphragms placed between the electrodes with some gelatinous material which,
coming in contact with a solution of a good conductor, will have no disturbing
action on the circulation of the ions as determined by the current.
Finally the fourth defect herein before mentioned, i.e. the diffusion of the
hydrogen, is totally suppressed, as the hydrogen set free at the cathodes is drawn
out of the electrolyzer by suction. The removal of the hydrogen in this way may
be assisted, by injecting a blast of carbonic acid into the cathode cells; but in that
case, due precautions must be taken to keep the temperature of the electrolyte
as high as is necessary for preventing the carbonate formed from settling within
the apparatus.
When the hydrogen escapes from the apparatus, it is advisable to force it through
a light hydrocarbon, and then to store it in a gasometer whence the gas thus car-
buretted may be fed to heating or illuminating appliances.
Having described the chief features of my invention, and the detailed phases it

page_text: comprises, I will now fully explain the working of my process it being supposed
that a saturated solution of chloride of sodium is used as an electrolyte.
In the drawings left with my Provisional Specification Fig. 1 is a diagrammatic
illustration of apparatus for carrying out my invention.
A and B are two vats, which at the beginning of the operation are filled with a
saturated solution of the salt to be used as an electrolyte-common salt in the
present case, and in which are suspended basketsk and containing solid chloride
of sodium intended to maintain the solution in a saturated state. These baskets
can be replaced by any other appliance that will admit of the liquid being constantly
in contact with the solid salt.
One of the vats (A) communicates by means of a pipe r with the first cell of
the cathodes, and the other vat (B), communicates by means of a pipe with the
first cell of the anodes, these electrodes belonging to an electrolizer C consisting of
a series of separate frames connected together in the same manner as those of a
filter press.
Fig. 1 shows the electrolyzer partly in vertical longitudinal section and partly
in side elevation; and
Fig. 2 shows it partly in horizontal section and partly in plan or top view.
Figs. 3 and 4 illustrate two of the frames forming part of the electrolyzer.
As shewn, the electrode cells 1, 2, 3, 4. . . formed by and between the frames R
and the diaphragms D, are connected one with the other in such a manner that
the electrolyte admitted into the apparatus by the pipe F (in Fig. 1) necessarily
passes through all the anode cells 1, 3, 5... whilst the electrolyte fed from
pipe (in Fig. 1) passes through all the cathode cells 2, 4, 6 It is
advisable to cause these liquid streams, when within the electrode cells, to flow
across them diagonally in an upward or downward direction which is effected by
providing for each. upper admission port cut in one of the standards of the frame,
a lower outlet port cut in the opposite standard of the same frame. For the sake
of clearness 1 shall describe the path followed by the stream of liquid electrolyte
passing from pipe F into the anode cell 1. The stream enters this cell through
port of in the left top corner (Fig. 3), flows out through o in the right bottom
corner, passes through the passage cut in the right bottom corner of the frame of
cell 2, and flows through in the right bottom corner of cell 3 and through this
cell which it leaves by the port of in the left top corner; it then passes through
the opening o cut in the left top corner of cell 4 (Fig. 4) then into cell 5 through
port in the left top corner, and escapes at o in the right bottom corner,
and so on.
In the same manner, the electrolyte supplied by pipe F2 is introduced into the
first cathode cell through port a¹ in the right top corner, leaves it through a² in
the left bottom corner, crosses the frame of cell 3 through the aperture provided in
the left bottom corner of the same, enters through a³ (Fig. 4) the left bottom corner
of cell 4 and so on. The pipes F1 F2 for supplying the electrolyte to the apparatus
may have cocks for the purpose of regulating the discharge.
The electrodes E may advantageously be in the form of cylindrical or prismatic
rods with fluted surfaces. The cathodes may be of iron. The anodes may be made
in the manner hereinbefore described.
The ions set free in the apparatus escape through the pipes G¹, G².
In order that the gases set free during the decomposing operation may escape
separately, the frames R have holes g'g' therethrough forming a continuous passage
placed above the upper lateral communicating passages, and these holes are con-
nected with the passages o.....
and a.
cut in the upper part of the framing
and through which flows the electrolyte, by means of passages respectively..
In consequence of the slope given to the underside of the top of each frame R (as
shewn in Figs. 3 and 4) the cells have their roofs inclined alternately to the right
and to the left, this arrangement facilitating the escape of the gases into the
passages through which the electrolyte passes, as above explained from one cell

page_text: into the next cell but one. The gases consequently flow with the electrolyte into
the passages o . . .
and a
whence they rise through the small pipes h²
into the passages gg. The gases thus separated from the liquids, flow out of the
apparatus through the separate pipe attachments i provided on the front-plate R'
and through pipes. The chlorine and hydrogen evolved at the anodes and
cathodes respectively are thus perfectly separated from each other, and are conveyed
through the pipes ³ ³ (Fig. 1) to any desired place.
If it be desired to blow a gas into the apparatus, this can be easily effected by
means of a pipe formed of successive passages 3 cut in the bottom members of
the frames R. Slots are provided in the the Hoor of those cells into which it is
intended to introduce the gas, and, as these slots reach downwards as far as the
passages, they allow gases to enter the respective cells from these passages.
A pipe serves to convey the gas to the conduit thus formed by the successive
passages g.
In the drawings the slots for the admission of gases are cut in the floor of the
cathode cells; they may be used either for blowing in air in order to remove hydrogen
from the electrodes and to prevent its depolarizing action, or carbonic acid for the
purpose of neutralizing the caustic alkalies formed.
The heating of the electrolyte is carried out either in the vats A and B or in the
electrolizer or simultaneously in each of these vessels.
When leaving the decomposing apparatus C, which is arranged with its axis
inclined so as to facilitate the escape of the gases, the liquids, viz. the solution of
sodium chloride coming from the anodes, and the solution of sodium chloride
containing caustic soda coming from the cathodes, are conveyed through the
pipe attachments G¹ G (Fig. 2) respectively and the pipes g, 9 (Fig. 1) into
vats M and N.
The vat M which receives the solution of sodium chloride coming from the
anodes and which always contains some chlorine, is closed, and has a pipe which
may convey the chlorine into the same vessel as that into which the chlorine set
free in the electrolizer C is conveyed by the pipe. A steam worm d, made of
lead, with closed or perforated walls, is placed on the bottom of the vat M and
serves for heating the liquid therein. This heating operation can also be effected
while the liquid is being conveyed into the vat B, by using a steam jet apparatus or
injector of lead instead of the pump p. The solution of electrolyte from the vat M
is forced by the pump p through the pipe into the vat B which is also closed, and
connected by a pipe with the gas holder, as chlorine is also set free in appreciable
quantities in the vat B owing to solid sodium chloride from the basket being
continually dissolved.
The vat N into which is conveyed the solution of electrolyte coming from the
cathodes and containing caustic soda, comprises, besides special cooling appliances,
a metallic perforated pipe e into which a compressor or a forcing pump F blows
carbonic acid taken from any suitable source, but preferably sucked from the kilus
in which is burned the lime which is to be combined with the liberated chlorine. A
basket suspended in the liquid in vat N holds sodium chloride in a solid state.
A stirring device e' may be arranged in the vat N in order to ensure the thorough
mixture of the liquids therein and to prevent the settling of large crystals of
carbonate of soda. As the liquid is always kept at its highest point of concentration,
since it passes through the basket containing solid sodium chloride, and as the
carbonate of soda is very difficult to dissolve in a saturated solution of sodium
chloride, the carbonate of soda is precipitated in the form of small crystals. After
leaving the rat N the solution is conveyed by the pipe either into settling or
decanting vessels P and P, or into a filter of known construction, whence it passes
to a pump p'. Or the solution may be forced through a filter press Q by a pump p³
and raised into the vat A, which it again leaves in order to again undergo the
successive treatment hereinbefore set forth. The pipes used in the latter case
are marked in the figures in dotted lines.
The crystallized carbonate of soda collected in the filter-press or in the decanting

page_text: vessels is dried in a hydro-extractor, cleansed with water or with a saturated solution
of soda, and may then be sold as crystallized carbonate of soda. The chlorine
carried away by pipe may be conveyed into chambers containing powdered
hydrate of lime and be thus converted into chloride of lime or bleaching powder;
it may also be used for other purposes.
From the foregoing description it will be understood that my process provides
means for directly obtaining pure crystallized carbonate of soda by precipitation
from the solution coming from the cathodes, and that consequently it is no longer
necessary, as was the case in other methods hitherto proposed, to perform a distinct
operation for transforming the bicarbonate of soda into monocarbonate. Since
the electrolyte after having been deprived of the alkali it contained, is completely
saturated again in the vat N before being conveyed back into the vat A, the
basket suspended in the latter vat for holding solid chloride of sodium may be
dispensed with according to circumstances.
As will be understood, the solution fed into the decomposing apparatus is main-
tained constant in quantity and always in a saturated condition, and it circulates
through the apparatus with such a velocity that the electrolyte in contact with
the electrodes can only retain a very small portion of the ions set free, which
are afterwards eliminated from the solution outside of the decomposing apparatus.
It is very advantageous to heat the solution by preference in the vats A and B,
as by this means the conductivity of the solution is increased and maintained, the
evolution of the chlorine set free at the anodes is accelerated, and the settling
of crystals of carbonate of soda at the cathodes is prevented. The settling of these
crystals in the vat N is on the other hand facilitated by cooling the liquid contained
in this vat.
As in the process described in my said former Specification so in the process
hereinbefore described the solution or electrolyte, whilst in the electrolizer, contains
but a very small quantity of the ions, in consequence of which all disturbing
influences are avoided and at the same time, the depolarization being lessened, a saving
is effected in the motive power required.
If it be desired to manufacture only bleaching agents in small quantities for use
in some industrial establishment, such as bleeching-or paper-works, the intro-
duction of carbonic acid into the solution which has circulated past the cathodes,
for the purpose of forming a precipitate of carbonate of soda may be dispensed
with. In this case, the liquid will preferably consist of a solution of chloride of
sodium and of caustic soda, and, when coming from the cathodes, it will be raised
directly into vat A, where it will dissolve sodium chloride until saturated, after
which it will again circulate through the cathode cells, absorb caustic soda, and
again rise into A, there to dissolve a further quantity of sodium chloride, these
operations being repeated in a continuous manner. It is advisable in this case, to
supply the anodes with a saturated and heated solution of sodium chloride, to which
sulphuric acid has been added. A slight addition of sulphuric acid up to 0.5%, to
the electrolyte which comes in contact with the anodes, is, in fact, advisable in all
cases, as the resulting sulphate of soda which remains in the liquid whilst it circulates
has a decomposing action on the hypochlorite and the chlorate present therein and
the formation of which cannot be entirely avoided. A sulphate of the alkali used
may be added instead of sulphuric acid if desired.
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. The herein described process for simultaneously producing chlorine and an
alkaline carbonate, by causing a heated saturated solution of an alkaline chloride
to rapidly circulate in two separate streams through an electrolytical decomposing
apparatus, one of the said streams namely that which flows past the anodes of the
apparatus, and to which a small quantity of sulphuric acid or of a sulphate of the
base used has been added, being conveyed after leaving the said apparatus through a

page_text: vessel provided with the alkaline chloride in a solid state whereby the liquid is
again completely saturated before being conveyed back to the anodes, the other
stream, namely that which flows past the cathodes of the apparatus being subjected
after leaving the said apparatus simultaneously to a cooling action, to contact with
solid alkaline chloride, and to the action of carbonic acid whereby a carbonate of
the alkali present is formed and precipitated from the solution which is afterwards
conveyed back to the cathode cells of the apparatus substantially as herein set
forth.
2. In the process referred to in the preceding claim, introducing carbonic acid
into the cathode cells, for the purpose of facilitating the escape of the hydrogen
set free, and maintaining the electrolyte at such a velocity and temperature as will
prevent carbonate of soda settling within the decomposing apparatus, substantially
as described.
3. For the purpose of carrying out the process referred to in Claims 1 and 2, an
electrolytical decomposing apparatus consisting of a succession of frames Rin
which the electrodes are arranged, these frames being separated from each other
by diaphragms and having in their upper parts passages y gl connected by other
passages h ' with the passages o.... and a through which the electrolytes are
caused to circulate, the said passages gy' allowing of the gases set free during the
electrolytical decomposition escaping separately from the ions substantially as
described and shewn.
4. In electrolytical decomposing apparatus of the kind referred to in the pre-
ceding claim, diaphragms D made of a permeable fabric or porous clay, the pores
of which are filled with gelatinous material mixed with a solution of salt corre-
sponding to that to be electrolytically decomposed, for the purpose of preventing
injurious mechanical diffusion from one cell to another of the liquids treated,
and at the same time of facilitating the circulation of the ions, substantially as
described.
5. In electrolytical decomposing apparatus of the kind referred to in Claim 3,
electrodes made by mixing together powdered retort carbon and a thickened solution
of wood cellulose in zinc chloride, these materials being kneaded together to form
a paste which is pressed into moulds and afterwards washed, then heated in a
muffle, impregnated with hydrocarbon, and again heated several times, substantially
as hereinbefore described for the purpose specified.
6. In electrolytical decomposing apparatus of the kind referred to in Claim 3,
electrodes the pores of which have been filled up with peroxide of lead obtained
either by covering the said electrodes with a layer of litharge and sulphate of
ammonia mixed together, or by boiling them in a saturated solution of lead acetate,
and afterwards electrolytically transforming the lead or the oxide of lead thus
obtained into peroxide of lead, this operation being repeated if required, substantially
as described for the purpose set forth.
7. For the manufacture or production of chlorine and an alkaline carbonate by
the process herein described, apparatus constructed, arranged, and operating
substantially as herein before described with reference to and shown in Fig. 1 of
the drawings.
Dated this 28th 1...
11001
C. KELLNER,
By L.W., per F.B.