Improvements in Electrolytic Apparatus.
Year: 1893

page_text: Date of Application, 13th Nov., 1893
°
Complete Specification Left, 13th Sept., 1894-Accepted, 3rd Nov., 1894
PROVISIONAL SPECIFICATION.
Improvements in Electrolytic Apparatus.
I, WILLIAM HAY CALDWELL, of Birnam, Cambridge, Gentleman, do hereby
declare the nature of this invention to be as follows:-
The object of this invention is to provide an improved diaphragm for use in an
electrolytic tank by means of which the substances produced at the anode and
cathode respectively are kept apart.
This diaphragm is formed of loose crystals of the salt which is being
electrolysed. A vertical wall of these crystals is maintained, by horizontally
placed strips of glass, porcelain, or other suitable material, arranged vertically one
above the other, from the bottom of the tank to the surface level of the solution,
after the manner of the laths of a Venetian blind. Further, each strip of glass is
placed at an angle to the floor of the tank, so as to binder the salt crystals
slipping through the spaces into the solution on either side.
The spacing in these glass walls is obtained by providing alternate strips with
suitable corrugations, or in any other convenient way.
Instead of building up the side walls of the diaphragm with separate pieces, as
described above, the same structure may be produced by a single casting of glass
or other suitable material.
Dated this 11th dow of November 1892
W. H. CALDWELL.
.
COMPLETE SPECIFICATION.
Improvements in Electrolytic Apparatus.
I, WILLIAM HAY CALDWELL, of Birnam, Cambridge, and also of Inverkeithing
in the County of Fife, Paper Maker, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed to be particularly described
and ascertained in and by the following statement:-
The object of this invention is to provide an improved diaphragm for use in an
electrolytic tank by means of which the substances produced at the anode and
cathode respectively are kept apart without appreciably increasing the resistance
of the cell.
This diaphragm is composed of loose crystals of the salt which is being electrolysed,
lying more or less tightly packed in a saturated solution of the same salt. A
vertical wall of these crystals is maintained by horizontally placed strips of glass,
porcelain, or other suitable material, arranged vertically one above the other,
from the bottom of the tank to the surface level of the solution, after the manner
of the laths of a Venetian. blind. Further, each strip of glass is placed at an
angle to the floor of the tank, so as to hinder the salt crystals slipping through the
spaces into the solution on either side.
The spacing in these glass walls is obtained by placing small pieces of glass
between the longer strips, or in any other convenient way, it might be by placing
a corrugated strip between each two flat strips.
In the accompanying drawings,
Figs. 1 and 2 are respectively a longitudinal vertical section and a plan, of part

page_text: of an electrolytic celi with diaphragms constructed according to this invention, and
suitable for the electrolysis of sodium chloride.
Figs. 3 and 4 show respectively in vertical cross section and plan, and to a
larger scale, part of one of the louvre-like side walls of a diaphragin according to
this invention.
A is a tank of suitable material, such as slate, divided vertically by vertical
partitions B into a series of salt compartments C, and electrode compartments D
and D in which latter compartments the anodes and cathodes E and E' are
respectively arranged. The partitions B are each composed of a number of
horizontally arranged flat strips of suitable material such as glass, placed
vertically one above the other with spaces between each two, and supported at their
ends in vertical grooves F formed in opposite sides of the tank. The said strips
are inclined to the bottom of the tank as shown, and may be spaced apart by
distance pieces 61 of suitable material, such as thin strips of glass or porcelain,
placed between them at suitable points, as for example at their ends in the
vertical grooves, as shown more clearly in Figs. 3 and 4. The breadth of each
groove F is suited to the width of the strip & used, due regard being had to the
incline to be given thereto. A convenient size for each strip bis inch thick x
1 inch broad x 2 feet long. The distance pieces or strips b may also be of similar
thickness and breadth, and say about in length. With these dimensions a
sufficient area for the passage of the current between the strips is obtained by
making the grooves F wide.
Crystals of sodium chloride are placed in each compartment C so as to fill it
from the bottom to the top of the tank, these crystals, which thus form a wall,
being held in position laterally by the louvre-like partitions B. The thickness of
the salt wall should be sufficient to allow the salt to, sink continuously as it
dissolves in the electrolyte, whilst remaining confined between the louvre-like
partitions. With a tank baving a depth of 24 inches, a sufficient breadth for the
salt wall would be 3 inches.
The top of the salt wall at the surface level of the solution, being always open,
can be conveniently fitted with a hopper holding a supply of salt crystals, thus
ensuring a constant feed to the diaphragm and any desired pressure on the salt
crystals in the electrolyte. One side of each hopper may conveniently be formed
by one side of the chlorine gas collecting cover G of the positive chamber D, and
the other side by a broad strip H of suitable material such as glass, arranged on
one side and at the top of the negative chamber D'. The ends of the several
hoppers may be formed by a rectangular frame H¹. When the cell is working,
a solution of sodium chloride is forced into the bottom of each anode and cathode
chamber D, D¹ respectively, preferably through inlets I from two longitudinally
arranged wooden conduits 11, 12, that are fixed in the lower corners of the tank Å
as shown, and are in communication with the bottom of a sodium chloride supply
compartment A' at one end of the tank A, one of the said conduits being arranged
to supply sodium chloride to the anode chambers, and the other, to the cathode
chambers. The overflow from each chamber takes place through outlets J placed
two inches below the top edge of the tank, all the overflow openings from the
anode chambers being arranged on one side and communicating with a wooden
conduit fixed to the outer side of the tank, and all the outlets from the cathode
chambers being arranged at the opposite side and in communication with another
conduit fixed to the exterior of the opposite side of the tank. The outlets J
and conduits J', J³, also serve as gas outlet passages from the respective chambers,
for which purpose the said conduits are made gas tight at the top, conveniently by
paraffin. The space between the two lower supply conduits 11 and below each
louvre-like partitions B, is closed by a vertical strip K of material such as glass,
retained at its ends in grooves K' in the sides of the said lower conduits.
With the construction described, if the salt crystals be small and be packed
tightly between the louvre-like partitions, the cathode chambers D' may be each
filled with mercury to constitute in effect a mercury cathode plate.

page_text: Having thus described the nature of my said invention and in what manner
the same is to be performed I declare that I am aware that it has before
been proposed to use diaphragms of salt crystals between the poles in electrolytic
apparatus, and I therefore make no general claim to such diaphragms otherwise
than when used in conjunction with louvre-like confining partitions as above
described and hereinafter claimed, nor do I claim broadly the use of glass strips
in an electrolytic tank, but what I do claim is :-
The hereinabove described improved electrolytic apparatus wherein, for keeping
apart the substances produced at the anode and cathode respectively, salt crystals
are maintained as a vertical wall or diaphragm between electrodes by and between
horizontally placed strips of suitable material such as glass or porcelain arranged
vertically one above the other, from the bottom of the tank to the surface level of
the solution, after the manner of the laths of a Venetian blind, leaving narrow
spaces for the electrodes, all as explained with reference to the drawings.
Dated this 13th day of September 1894.
For the Applicant,
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C., Chartered Patent Agent.