Improvements in Apparatus to be used for Electrolytic Purposes.
Year: 1890

page_text: Date of Application, 12th Feb., 1890
Complete Specification Left, 1st Sept., 1890-Accepted, 7th Feb., 1891
PROVISIONAL SPECIFICATION..
Improvements in Apparatus to be used for Electrolytic Purposes.
We JAMES CHARLES RICHARDSON of 23 Claremont Square, Clerkenwell, in
the County of Middlesex, Electrical Engineer, and TREVENEN JAMES HOLLAND
of Ivymeath, Snodland, in the County of Kent, J.P., C.B., Colonel in Her
Majesty's Army, do hereby declare the nature of this invention to be as follows:-
The main object of the present invention is to facilitate the electrical decom-
position of common salt (chloride of sodium) for the production of chlorine and
caustic soda suitable for use in the manufacture of paper, but the invention is also
applicable in electrolysis for other purposes.
When chloride of sodium in solution is decomposed by an electric current with an
insoluble anode, it is resolved into its elements, chlorine and sodium, the chlorine
being set free next the anode, or pole by which the current enters the solution, and
the sodium, which eventually becomes caustic soda by the decomposition of the
water present, being set free next the cathode, or pole by which the current leaves
the solution, hydrogen being at the same time given off at that pole.
In tanks usually employed, the anode and cathode are separated from each other
by a porous diaphragm or partition, which will more or less prevent the liberated
elements from re-combining, while the passage of the current is still permitted.
The use of such porous partitions is generally considered objectionable, on account
of the cost of the material, its fragility, and the difficulty of obtaining the partitions
of sufficiently large area for use on a practical scale. The greatest objection is
however the resistance which the porous material offers to the passage of the electric
current.
The present invention is specially designed to remedy or lessen these defects.
In the electrolysis of chloride of sodium in solution with an insoluble anode,
chlorine gas is set free about the anode, and finds its way quickly to the surface,
while caustic soda formed about the cathode, has a tendency, owing to its
density, to descend. Hydrogen gas is however at the same time set free at the
cathode, and by the commotion thereby occasioned in the liquid, the caustic soda is
also carried upward to the surface. Thus, if the caustic soda and the chlorine are
allowed to do so, they will come in contact and re-combine. To avoid this re-com-
bination, according to the present invention the electrodes are contained in separate
compartments formed in the tank by means of a non-porous partition or partitions.
Such partition does not however extend throughout the whole section of the
solution under treatment, but leaves a space unobstructed at the bottom of the tank.
We may here mention, that in some cases, as when the products of electrolysis are
directly denser than the electrolyte, for instance, when a soluble anode is employed,
the unobstructed space may be at the top. By this space, whether at top or
bottom, the current will have free passage from the anode to the cathode suitably
placed on either side of the partition, and the resistance being thus materially
diminished, the current can be used to better advantage.
The products of the electrolysis, whether of chloride of sodium, potass, or other
alkali, are conducted by suitably arranged conduits to vessels or receptacles
prepared to receive them.
The non-porous partition, as also the tank, may be of any material which is not
attacked by the electrolyte under treatment, nor by the resulting elements or
compounds which may be set free, or formed by the electrolysis, to an extent likely
to effect destruction of the partition, or contamination of the solution.
Dated this 19th day of Fehmary 1890.
NEWTON & SON,
Agents for the Applicants.

page_text: COMPLETE SPECIFICATION.
Improvements in Apparatus to be used for Electrolytic Purposes.
We JAMES CHARLES RICHARDSON of 23 Claremont Square, Clerkenwell, in
the County of Middlesex, Electrical Engineer, and TREVENEN JAMES HOLLAND
of Ivymeath, Snodland, in the County of Kent, J.P., C.B., Colonel in Her
Majesty's Army, 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 main object of the present invention is to facilitate the electrical decom-
position of common salt (chloride of sodium), for the production of chlorine and
caustic soda suitable for use in the manufacture of paper, but the invention is also
applicable in electrolysis for other purposes.
When chloride of sodium in solution is decomposed by an electric current with
an insoluble anode, it is resolved into its elements, chlorine and sodium, the chlorine
being set free next the anóde, or pole by which the current enters the solution, and
the sodium, which eventually becomes caustic soda by the decomposition of the
water present, being set free next the cathode or pole by which the current leaves
the solution, hydrogen being at the same time given off at that pole.
In tanks usually employed, the anode and cathode are separated from each other
by a porous diaphragm or partition, which will more or less prevent the liberated
elements from re-combining, while the passage of the current is still permitted.
The use of such porous partitions is generally considered objectionable, on
account of the cost of the material, its fragility, and the difficulty of obtaining the
partitions of sufficiently large area for use on a practical scale. The greatest
objection is, however, the resistance which the porous material offers to the passage
of the electric current.
The present invention is specially designed to remedy or lessen these defects.
In the electrolysis of chloride of sodium in solution with an insoluble anode,
chlorine gas is set free about the anode, and finds its way quickly to the surface,
while caustic soda formed about the cathode has a tendency, owing to its density, to
descend. Hydrogen gas is however at the same time. set free at the cathode, and
by the commotion thereby occasioned in the liquid, the caustic soda is also carried
upward to the surface. Thus, if the caustic soda and the chlorine are allowed to
do so, they will come in contact and recombine. To avoid this re-combination,
according to the present invention the electrodes are contained in separate com-
partments formed in the tank by means of a non-porous partition or partitions.
Such partition does not extend, however, throughout the whole section of the
solution under treatment, for the separation of the elements necessary only at the
point where the re-combination would take place were there no partition.
The remaining space is left unobstructed for the free passage of the current through
the solution.
In the accompanying drawing, we have illustrated tanks for the decomposition of
chloride of sodium, constructed on the lines of our invention.
Fig. 1 shews in transverse section a tank in its simplest form, together with
chambers for the collection of the chlorine.
Fig. 2 is a vertical section of a tank with the partitions somewhat differently
arranged.
Fig. 3 is a vertical section of a series of tanks arranged one over the other.
Fig. 4 is a longitudinal section of tank containing a series of compartments placed
side by side.
Fig. 5 is a partial plan of Fig. 4, and
Fig. 6 is a vertical section, on an enlarged scale, of a detail to be presently
referred to.
In Fig. 1, A is a covered tank of slate or other suitable material, divided longi-
tudinally into three compartments, B C D, by partitions a a, extending from the
cover downward to within a small distance of the bottom. Salt in solution is fed

page_text: into the tank through pipes 66 to a suitable height, leaving room for the formation
of the chlorine and hydrogen gas.
The anodes or positive electrodes, which may be carbon rods passing through the
sides of the tank, are arranged in the compartments B and D, and are supported by
leaden or other plugs X in electrical connection with a conductor Y (see Fig. 6)
running the length of the tank outside.
The cathode, or negative electrode, may be of copper strip or wire in the shape
of a grid, as indicated in the drawing. The electrodes being connected to a
dynamo or other source of electricity, the current passes from the anodes or
positive electrodes to the negative or cathode through the salt solution, and the
decomposition of the latter commences. The chlorine gas which forms next the
anode, collects in the chambers B and D at the surface of the liquid, and from
thence it may be conducted, by pipes e e, to closed chambers E E, where it may be
absorbed by lime, for the production of bleaching powder. The chlorine may
however, if preferred, be stored as a gas, if required in that form, and suitable
receivers can be provided. f is a rake for turning over the lime in the chamber E,
and exposing fresh surfaces to the action of the chlorine gas.
At the same time, the formation of caustic soda goes on at the negative electrode
in the chamber C. Hydrogen gas is also formed by the decomposition of the water,
and rising rapidly to the surface, carries with it the caustic soda in solution. The
hydrogen gas passes away up the pipe C' to a suitable receiver, and the caustic soda
solution, as soon as sufficiently strong, is drawn off by the pipe c. It is preferred to
draw off the caustic, and to admit fresh salt solution continuously, and to auto-
matically regulate the inflow and outflow the one by the other, as may be readily
done by means of taps and valves, as soon as the rate of production of the requisite
strength of caustic soda shall have been determined.
In Fig. 2 the cathodes are arranged in troughs extending lengthwise of the tank,
which serve to make separate compartments CC for the formation of the caustic
soda. CC are pipes for the escape of the hydrogen, and ce are outflow pipes for
the caustic soda solution. The chlorine is formed on the surface of the liquid, near
the anodes, in the body of the tank.
Fig. 3 shows a series of tanks mounted one over the other, each tank being
divided into two compartments, B and C, by a single partition. The anode com-
partments B are provided with salt solution admission pipes b, and chlorine escape
pipes e, as before, and the cathode chambers C are furnished with hydrogen pipes C¹
and caustic soda solution pipe c.
Figs. 4 and 5 serve merely to show how a long, shallow, and comparatively.
narrow tank may be divided up, the anodes being all connected together on one
side, and the cathodes on the other. The anode chambers B, when the tank is of
metal likely to suffer from contact with chlorine gas, may be enamelled, or lined
with glass, porcelain, or similar material, not so affected by chlorine gas.
In tanks thus constructed, it will be understood that recombination of elements
cannot take place, and at the same time partial divisions offer an unobstructed
passage to the electric current between the electrodes.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, we declare that what
we claim is :-
Apparatus to be used in electrical decomposition of salt and other solutions, con-
sisting of a tank divided by a partition or partitions of non-porous character,
extending through part of the section of the solution under treatment, and serving
to maintain the separation of the elements produced, and thereby preventing their
re-combination, in the manner hereinbefore described.
Dated this 29th day of August 1890.
NEWTON & SON,
Agents for the Applicants.