Improvements in Electrolytic Decomposing Apparatus.
Year: 1899

page_text: PROVISIONAL SPECIFICATION.
Improvements in Electrolytic Decomposing Apparatus.
We, TREVENEN JAMES HOLLAND, of Mount Ephraim House, Tunbridge Wells,
Colonel, C.B., Retired List, H.M. Army, and ARTHUR PILLANS LAURIE, M.A.,
D.Sc., of Monkwood Cottage, Loughton, Essex, Consulting Chemist, do hereby
declare the nature of this invention to be as follows:-
The present invention is directed to the construction and arrangement of
apparatus used in the electrolytic decomposition of solutions of alkali salts, with
the view of economizing the electric current employed, and of reducing the
original cost of an electrolytic plant, and of the labour bill for attendance thereon
during use.
In constructing apparatus according to this invention, to be employed in the
electrolysis of, say, a solution of chloride of sodium, to obtain chlorine gas and
caustic soda therefrom, we make a tank for the solution, of iron plates bolted
together, and divided transversely at intervals by partition plates of the same
metal, extending to within a short distance of the bottom of the tank, and in
metallic connection, by bolts or rivets, with the sides thereof. This tank forms
in itself the cathode, and is connected in any suitable manner to the negative
pole of the current generator.
The
The anode cells are boxes formed of porous material set down within the tank
between the partitions before mentioned. These boxes have detachable covers,
which carry positive electrodes depending therefrom, and extending down into
the boxes, the upper ends being extended upward thro' the covers to the
outside, where they are connected to the positive lead of the generator.
covers of the boxes are furnished with a pipe for leading off the chlorine gas
liberated at the anodes, and they are also furnished with a receptacle for salt
extending into the solution with which the boxes are filled, to within a short
distance of their covers. These receptacles are accessible from the outside, and
are kept supplied with salt to maintain the strength of the brine being decom-
posed. The arrangement is such, that there can be no escape of gas through the
salt receptacles. When the boxes are filled with solution, the covers are luted
down, and there will be no need to remove them for a long time, provided fresh
salt is frequently added, as above explained.
The iron tank is itself supplied with brine from time to time. The caustic
soda is formed in the spaces between the porous boxes and the iron tank, and is
drawn off by means of a tap as soon as it is sufficiently strong. The size of the
porous boxes is proportioned to the size of the compartments of the tank, so
that the space around the boxes is somewhat narrow, the object being to ensure
rapidity of decomposition outside the boxes, by reason of the small quantity of
solution being acted on. Furthermore, the distance between the anode, dia-
phragm, and cathode, is so regulated that the electro motive force required is
low, and the ratio between these distances is that best suited to a high current
efficiency.
The above described arrangement will be found easy and cheap to construct,

page_text: and economical as to current employed. The apparatus, however, requires little
attention when running, and thus an economy in the wages of attendants is
effected.
NEWTON & SON,
Agents for the Applicants.
.
Improvements in Electrolytic Decomposing Apparatus.
We, TREVENEN JAMES HOLLAND, of Mount Ephraim House, Tunbridge Wells,
Colonel, C.B., Retired List, H.M. Army, and ARTHUR PILLANS LAURIE, M.A.,
D.Sc., of Monkwood Cottage, Loughton, Essex, Consulting Chemist, do hereby
declare the nature of this invention and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement:
The present invention is directed to the construction and arrangement of
apparatus used in the electrolytic decomposition of solutions of alkali salts, with
the view of economizing the electric current employed, and of reducing the
original cost of an electrolytic plant, and of the labour bill for attendance thereon
during use.
In the accompanying drawing, we have shewn an electrolytic apparatus
embodying our improvements
Fig. 18 a longitudinal section;
Fig. 2 is a transverse section;
Fig. 3 is a plan view; and
Fig. 4 is a longitudinal section, on a small scale, to illustrate a slight modifica-
tion.
The apparatus which is shown is suitable for use in the decomposition of chloride
of sodium, comprises an outer tank A. preferably of iron, divided transversely
at intervals by partitions a of the same metal. In the spaces between the parti-
tions a, are set cells B, which are closed boxes of porous material. The covers
of these cells B support the anodes b, which may conveniently be carbon rods or
plates arranged near the sides. These anodes project through the cover, and
are connected at their upper ends to positive conductors c branching from the
main conductor. C, which leads from the generator, while the lower. ends are
immersed in the electrolyte contained in the cells. The tank A and partitions
form the negative electrodes, or the partitions only, if the body of the tank is
of non-metallic material. A¹ is the negative conductor bolted to the tank side,
. and connecting with the positive conductor of the next tank, or with the generator.
The partitions a, as shewn in Fig. 1, extend to within a short distance of the
bottom of the tank, and the solution in the said tank is free to pass beneath them
from one compartment to the next.
In Fig. 4, however, the partitions are alternately arranged clear of the bottom,
and in contact therewith, so that brine fed into the tank at the end by the
cock D, finds its way in a serpentine course to the opposite end, where there is
an outlet E. This is a continuous method of feeding, which is convenient when
it is not desired to employ the tank A entirely, as is necessary when the outlet
cock E is placed, as in Fig. 1, at the bottom of the tank. Both the tank A and
the cells B are charged with brine, and the latter, being sealed, are not emptied
except at rare intervals. The strength of the brine in the cells B is maintained
by means of fresh salt supplied to receptacles F, which extend into the solution

page_text: thro' the covers of the cells B. These receptacles F, which are accessible from
the outside, yield up their contents thro' perforations situated below the
electrolyte level, as the decomposition proceeds, without permitting the escape
of the gases liberated.
gare escape pipes for chlorine gas liberated in the anode cells, communicating
with the main gas pipe G, which conducts the gas away for storage.
The caustic soda is formed in the spaces between the porous boxes and the
iron partitions, and is drawn off by means of the tap as soon as it is sufficiently
strong. The size of the porous boxes is proportioned to the size of the com-
partments of the tank, so that the space around the boxes is somewhat narrow,
the object being to ensure rapidity of decomposition outside the boxes, by reason
of the small quantity of solution being acted on.
Furthermore, the distance between the anode diaphragm and cathode is so
regulated that the electro-motive force required is low, and the ratio between
these distances is that best suited to a high current efficiency.
The above described arrangement will be found easy and cheap to construct,
and economical as to current employed. The apparatus, however, requires little
attention when running, and thus an economy in the wages of attendants is
effected.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is:-
Electrolytic apparatus consisting of an outer tank divided at intervals by
transverse metal plates forming the cathodes; a series of closed porous boxes
arranged between the said plates and containing the anodes; means for supplying
salt to the anode cells, for maintaining the strength of the electrolyte therein,
without opening the cells; means for leading off the gases liberated in such
cells; and means for supplying and withdrawing solution to and from the outer
tank, whether continuously or at intervals; all arranged and operating sub-
stantially as described with reference to the accompanying drawing.
Dated this 21st day of August 1899.