Improvements in Electrolytic Apparatus.
Year: 1896

page_text: PROVISIONAL SPECIFICATION.
Improvements in Electrolytic Apparatus.
I, TREVENEN JAMES HOLLAND, of Mount Ephraim House, Tunbridge Wells,
Colonel, C.B., Retired List, H.M. Army, do hereby declare the nature of this
invention to be as follows:-
The present invention relates to tanks or vessels wherein solution to be electro-
lytically decomposed is contained, the object of the invention being to improve and
simplify the construction of the said tanks, and to reduce resistance and economise
working.
The form of tank to which this invention more particularly relates is that which
comprises a series of positive and negative cells arranged alternately in a long
shallow vessel of slate or similar material, and separated by partitions extending
downward into the solution not quite to the bottom of the tank.
Tanks of this description are used for decomposing solutions of chloride of sodium
or chloride of potassium, with the view to producing caustic soda or potash and
chlorine gas.
The anode or positive cells, where the chlorine gas is liberated, are covered so
as to catch the gas as it leaves the solution, and pipes are provided for conveying
it away to a suitable receiver. The negative or cathode cells are usually left
uncovered.
The fitting and fixing of the covers, which are of the same materials as the tanks,
is a source of considerable trouble, owing to the difficulty which there is in closing
the joints, so as to prevent escape, and to exclude atmosphereic air, which would
dilute the chlorine gas.
I propose to obviate the difficulty in the following manner :-
Instead of dividing the tank into cells by means of transverse partitions let into
the sides of the tanks, and covering the cells by detached covers cemented into
position, I now take an open tank provided internally with longitudinally-extending-
ledges or narrow shelves at a suitable depth. The covered cells are, according to
my invention, to consist of inverted boxes of earthenware or other suitable material,
the ends of which boxes, when introduced into the tank, will rest on the ledges or
shelves before mentioned in the sides of the tanks. These boxes, of which there
will be any suitable number in the tank, will contain the electrodes, and will be
pierced to receive the solution supply pipe and the gas exit pipe.
In other respects, however, there will be no joints, as the cover is formed by the
bottom of the inverted box, and the whole cell is solid; consequently there will be
no liability to leak. The boxes can be readily lifted in and out of the tank, and as
they merely rest on the ledges provided for their reception, there is no trouble in
fixing them.
It will be found that with the above described arrangement, there is a reduction
in electrical resistance which permits an economy in the working current.
Dated this 3rd day of June 1806
NEWTON & SON,
Agents for the Applicant.

page_text: I TREVENEN JAMES HOLLAND of Mount Ephraim House, Tunbridge Wells,
Colonel C.B., Retired List H.M. 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 present invention has reference to apparatus for the electrical decomposition
of solutions, particularly solutions of chloride of sodium and chloride of potassium,.
with the view of obtaining chlorine gas and caustic soda or caustic potash therefrom.
The apparatus at present commonly employed comprises a long shallow tank or
tanks of glass, slate, or similar non-conducting material, divide into cells for the
reception of the electrodes arranged alternately positive and negative in the tank.
The anode or positive cells, where the chlorine gas is liberated, are covered so as
to catch the gas as it leaves the solution and pipes are provided for conveying it
away to a suitable receiver. The negative or cathode cells are left uncovered.
The fitting and fixing of the covers and sides of the anode cells (which are
generally, under existing circumstances, of the same materials as the tanks, and
form therewith a solid and expensive construction) entail considerable expense in
grooving the material of which the tanks are made, to enable covers and partitions
to be fitted in, and are sources of considerable trouble, owing to the difficulty which
there is in closing the joints and keeping them air-tight, so as to prevent escape of
chlorine gas and the inlet of atmospheric air, the admission of which dilutes or
considerably weakens the chlorine gas.
I propose to obviate these difficulties, and to obtain, moreover, considerable
advantage in economy of working, in the following manner :-
Instead of dividing the tanks into cells by means of transverse partitions let into
the grooved sides of the tanks, and instead of covering the anode cells, as at present,
by detached lids cemented into position, I now take a simple rectangular ungrooved
tank, and I form the cells by dropping into the said tank, inverted boxes of earthen-
ware or other suitable moulded material.
These boxes, of which there will be a suitable number in each tank, will constitute
removable air-tight cells for the positive electrodes, and their sides will act as partitions
to separate the positive and negative electrodes arranged alternately in the tank.
The boxes, which are all in one piece, will be pierced to receive the solution supply
pipe and the gas exit pipe; in other respects, however, there will no joints, and con-
sequently no leakage. The boxes can, moreover, be readily lifted in and out of the
tank, and there will be no trouble in fixing them.
If the boxes are made of porous earthenware (which is preferable), the current will
be able to pass through the sides, as well as below and around them, thus effecting a
reduction in resistance and an economy in current. A further economy of current,
or an improvement in efficiency, is effected by the employment of negative electrodes
of special form, made of wire, as hereafter described.
In the accompanying drawing, I have shown an electrolytic tank suitable for
decomposing a solution of chloride of sodium, embodying my improvements.
Fig. 1 is a longitudinal section on the line x-x of Fig: 2.
Fig. 2 is a plan view; and
Fig. 3 is a transverse section through one of the anode cells.
Fig. 4 shows, detached, in side view, the special form of cathode.
A is an open tank, built of slate or other suitable material unaffected chemically or
electrolytically by the process.
a a are narrow ledges extending along the sides of the tank from end to end, inside
the tank.

page_text: bare boxes of earthenware or similar material, of a length slightly less than the
width of the tank A. These boxes are inverted, and dropped at intervals into the
tank A so that they rest on the ledges a in the manner shown.
It may be here remarked that various means may be employed for holding the
inverted boxes b at a proper depth in the tank; the ledges a being a convenient
arrangement, have been selected for present illustration.
The inverted boxes b form covered removable air-tight chambers or cells for the
anodes or positive electrodes, and the uncovered spaces between the said covered
cells constitute uncovered cells for the wire grid cathodes or negative electrodes e.
The tank is thus divided into compartments by partitions composed of the sides of
the said air-tight cells 6, extending downward into the solution in the tank a distance
sufficient to properly separate the electrodes, which are arranged alternately positive
and negative along the length of the tank. The positive electrodes may be of any
suitable kind, but, as indicated in Fig. 3 of the drawing, they are carbon blocks
attached to a rod or bar, which is bolted to the bottom of the inverted box b.
The cathodes e will preferably consist of the special form of wire grids shown in
Fig. 4, supported by rods passed through the upturned sides e¹ of the said grids,
and resting on the edges of the tank A.
The said cathodes are of wire basket work, by preference double, and of
shape
in longitudinal section (see Fig. 4); the upturned sides e serve for the attachment
of the leads, and to support the electrodes as already mentioned.
+ and - - indicate, respectively, the leads for conveying the electric current from
the generator (not shown) to the anodes and cathodes.
Cis the main solution supply pipe for delivering, by means of the funnels c,
the solution to be decomposed to the positive cells b. d are connecting pipes for
leading away the gases formed in the boxes b to the discharge main pipe D.
Besides the advantages of construction above mentioned, it will be found that,
with the above described arrangement, the partitions may be of porous earthen-
ware, while the main body of the tank is non-porous. The current will therefore
be able to pass around and below the partitions, and also through them, thereby
effecting a reduction in electrical resistance, which permits a great economy in the
working current.
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. A vessel for containing a solution to be electrolytically decomposed, consisting
of a shallow open tank of glass, slate, or other suitable. material, and inverted
removable boxes of earthenware supported therein as explained, and constituting
closed airtight cells, while their sides act as partitions for separating the electrodes
substantially as described with reference to the accompanying drawing.
2. A vessel for containing a solution to be electrolytically decomposed, consisting
of a shallow open tank of slate or similar material, and inverted removable boxes
supported therein as explained, and constituting air-tight porous anode cells, while
their sides act as partitions for separating the positive from the negative electrodes,
the latter being grids of iron or copper wire formed substantially as described.
Dated this 14th day of October 1896.
NEWTON & SON,
Agents for the Applicant.