Improvements in Cells applicable for the Production of Chlorine and Alkali Metal Amalgams by Electrolytic Decomposition of Solu- tions of Alkaline Chlorides
Year: 1898

page_text: Improvements in Cells applicable for the Production of Chlorine and
Alkali Metal Amalgams by Electrolytic Decomposition of Solu-
tions of Alkaline Chlorides,
I, JOSIAH WYCKLIFFE KYNASTON, of Oak Terrace, Beech Street, Liverpool, in
the County of Lancaster, Analytical Chemist, do hereby declare the nature of this
invention to be as follows:-
The result of decomposition by electrolysis of solutions of alkaline chlorides,
when metallic mercury is used as the cathode, is the climination of chlorine with
the simultaneous production of an alkaline metal amalgam. The chlorine obtained
by such decomposition is usually in a state of high purity, but, by the usual modes
of working, the alkaline metal amalgam produced contains only a very minute
proportion of alkali metal. Several forms of cell of this description are com-
plicated, by combination with the actual decomposing cell, of one or more
compartments in which the mercury is partially denuded of alkali metal and is
returned to the decomposing cell proper in this condition. And further, in the
usual forms of this description of cell, the proportion of cathode surface to the
quantity of solution undergoing decomposition is so small that the rate of
electrolysis is necessarily very slow and the products very restricted in quantity.
And lastly, unless the chloride solutions to be composed in these cells, are in a
condition of high purity, the mercury becomes so fouled" by foreign matters
that it ceases to be effective for its purpose.
4
My improvements in the construction of cells, to be employed in the electrolysis
of alkaline chloride solutions, relate to the description of cell in which mercury
is used as the cathode with the usual anode of carbon, and the improved form of
my new cell avoids the inconveniences and imperfections attaching to this
description of cell as they have hitherto been constructed.
I use as the outer enclosure of the cell, a tank or cistern built up of flagstone
slate or similar natural material or I may use the artificial stone now commonly
produced in large slabs or blocks. The stone forming the bottom of the enclosure
must be of sufficient thickness and strength to bear, without fear of fracture, the
weight to be placed upon it, that is, it must be considerably stronger than the
sides, ends and cover to be erected upon it. The joints are made tight by.
the insertion of india-rubber cord in grooves and the structure is firmly braced
by means of brackets and bolts exactly in the manner employed in the con-
struction of hydrochloric acid cisterns in alkali works.
In the simplest form of the cell, which I have been able to design and which
I term a single cell, the approximate internal dimensions of the enclosure will be
as follows: height about half the length, and breadth about one-sixth the
length. For instance, in a cell of which the length is ten feet, I make the
height six feet and the breadth, one foot nine inches.

page_text: Upon each of the sides of such an enclosure, and running the entire length, I
arrange a series of narrow shelves of stone, natural or artificial, slate, ebonite,
vulcanite or similar material at a distance of a few inches from each other, the
uppermost shelf being about one foot from the top of the enclosure and the lowest
three or four inches from the bottom. The shelves are hollowed out on the upper
surface to the depth of about one half inch, the depression reaching to within
one-quarter inch of the edges of the shelves. At the alternate ends of each of
adjacent shelves and three inches from the ends, a ridge, one inch wide and
one-eighth of an inch lower than the upper edge of the shelf, runs across it and
in the depression beyond the ridge, a hole, one inch in diameter, is bored through
the shelf. Holes are bored through each of the sides or ends of the enclosure at a
short distance above the level of the uppermost of the shelves and an earthenware
pipe for the conveyance of mercury to the shelves is cemented firmly in the
apertures. A hole is also bored through the stone forming the bottom of the
enclosure and through this a wrought or cast iron pipe reaching to the upper
surface of the stone is firmly and tightly fixed. This pipe serves for the with-
drawal of the mercury amalgam from the cell.
The carbon anodes are suspended through the
central space between the shelves and extend to
bottom of the cell.
cover of the enclosure in the
within a short distance of the
The pipes for conveying the chloride solution to and withdrawing it from
the cell are conveniently passed through the cover of the cell and the usual
arrangements are provided for maintaining a constant level of solution within the
cell. I prefer to pass the solution into the cell at or near to its boiling point of
temperature. The pipe for carrying away the chlorine gas as it is evolved is
conveniently attached to an orifice in the cover of the cell.
I construct what I term a double cell exactly upon the same principles as
above described for a single cell, but the width of the enclosure is increased to the
requisite extent, and in addition to the two series of side shelves, I fix in the
centre of the space between the side a third series of shelves, the breadth of each
of which is the sum of the width of two of the side shelves. In this 66 double
cell, two sets of anode carbons are used and are suspended in the spaces between
each of the series of side shelves and the central series of shelves.
It is obvious that in the same way a triple or quadruple cell may be constructed.
In putting the cell into operation, the chloride solution is run into the cell until
the uppermost of the shelves is well covered. Mercury is then passed in and,
falling upon the uppermost shelf of each series, it fills the depression to the
depth of about three eighths of an inch and then falls through the opening
at the further end to the next shelf and so on until all the shelves are charged.
The supply of mercury is continued until the bottom of the cell is also covered
to the depth of about half an inch. Connection is now made between the sus-
pended carbons and the positive pole of an electric current and between the
mercury on the bottom of the cell and the negative pole, the latter most con-
veniently by means of the iron pipe through which the amalgam is withdrawn
from the cell. The flow of mercury into the cell is continued in a constant stream
so regulated that the alkali metal amalgam flows out as rich in alkali metal as
it is possible practically to produce it whilst retaining perfect fluidity at the
temperature at which the cell is worked. The chlorine evolved passes from the
cell through the pipe provided for its escape.
Under ordinary circumstances the electric current flows freely through the
amalgam on the bottom of the cell to that in the series of shelves by means of
the constant stream falling from one to the other, but I prefer to place the metal
on each of the shelves in independent metallic connection with each other of the
series and the whole in independent connection with the metal on the floor of
the cell. It will be understood however that this is not essential.
In thus describing my experimental apparatus, I do not bind myself to these

page_text: exact details of arrangement as it is obvious that the cell can be made of other
materials and of cylindrical or other form.
DL: 004 law of L.... 1808
W. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool,
Patent Agents for the Applicant.
Improvements in Cells applicable for the Production of Chlorine and
Alkali Metal Amalgams by Electrolytic Decomposition of Solu-
tions of Alkaline Chlorides.
I, JOSIAH WYCKLIFFE KYNASTON, of Oak Terrace, Beech Street, Liverpool, in
the County of Lancaster, Analytical Chemist, 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 result of decomposition by electrolysis of solutions of alkaline chlorides,
when metallic mercury is used as the cathode, is the elimination of chlorine with
the simultaneous production of an alkaline metal amalgam. The chlorine obtained
by such decomposition is usually in a state of high purity, but by the usual modes
of working, the alkaline metal amalgam produced contains only a very minute
proportion of alkali metal. Several forms of cell of this description are com-
plicated, by combination with the actual decomposing cell, of one or more
compartments in which the mercury is partially denuded of alkali metal and is
returned to the decomposing cell proper in this condition. And further, in some
of the forms of this description of cell, the proportion of cathode surface to the
quantity of solution undergoing decomposition is so small that the rate of
electrolysis is necessarily very slow and the products very restricted in quantity.
And, lastly, unless the chloride solutions, to be decomposed in these cells, are in a
condition of high purity, the mercury becomes so "fouled" by foreign matters
that it ceases to be effective for its purpose.
My improvements in the construction of cells, to be employed in the electrolysis
of alkaline chloride solutions, relate to the description of cell in which mercury
is used as the cathode with the usual anode of carbon, and the improved form of
my new cell avoids the inconveniences and imperfections attaching to this
description of cell as they have hitherto been constructed.
use as
the outer enclosure of the cell, a tank or cistern built up of flagstone, slate
or similar natural material, or I may use the artificial stone now commonly
produced in large slabs or blocks. The stone forming the bottom of the enclosure
must be of sufficient thickness and strength to bear, without fear of fracture, the
weight to be placed upon it. The joints are made tight by the insertion of
india-rubber cord in grooves (shown at B in the drawings) and the structure is
firmly braced by means of brackets (C) and bolts (D) exactly in the manner
employed in the construction of hydrochloric acid cisterns in alkali works.
In the simplest form of the cell which I have designed and which
I term a single cell, the approximate internal dimensions of the enclosure will be
as follows: height about half the length, and breadth about one-sixth the
length. For instance, in a cell of which the length is ten feet, I make the
height six feet and the breadth, one foot nine inches to two feet.
In the drawings attached hereto,-
Figure 1 is a transverse vertical section and

page_text: Figure 2 a plan of what I call a single cell.
Figure 3 a transverse vertical section of a modification showing a cell with
two sets of anodes and three series of cathode shelves or double cell.
.
Figure 4 section of detail of either a single or a double cell.
Figure 5 is a longitudinal section of either single or double cell.
Referring first to Figures 1, 2 and 4,-Upon each of the sides of the flagstone
enclosure A and running the entire length, I arrange a series of narrow shelves E
of stone, natural or artificial, slate, glass, ebonite, vulcanite or similar material
at a distance of a few inches from each other, the uppermost shelf being about
one foot from the top of the enclosure and the lowest three or four inches from the
bottom. The shelves are hollowed out on the upper surface to the depth of one
half inch, the depression reaching to within one quarter inch of the edges of
the shelves. At the alternate ends of each of adjacent shelves and about three
inches from the ends, a ridge F about one inch wide and about one-eighth of an
inch lower than the upper edge of the shelf, runs across it and in the depression
beyond the ridge a hole G about one inch in diameter, is bored through the shelf.
Holes are bored through each of the sides or ends of the enclosure at a short
distance above the level of the uppermost of the shelves and an earthenware
pipe for the conveyance of mercury to the shelves is cemented firmly in the
apertures. A hole I is also bored through the stone forming the bottom of the
enclosure and through this a wrought or cast iron pipe J reaching to the upper
surface of the stone is firmly and tightly fixed. This pipe serves for the with-
drawal of the mercury amalgam from the cell. The carbon anodes K are sus-
pended through the cover of the enclosure in the central space between the
shelves and extend to within a short distance of the bottom of the cell.
The pipes for conveying the chloride solution to and withdrawing it from
the cell are conveniently passed through the cover of the cell, in which case the usual
arrangements are provided for maintaining a constant level of solution within the
cell. Or the feed pipe may be passed through the side or end of the enclosure
near the bottom, and the outlet also through the side or end nine or ten inches
from the top. I prefer to pass the solution into the cell at or near to its boiling
point of temperature.
The pipe L for carrying away the chlorine gas as it is evolved is conveniently
attached to an orifice in the cover of the cell.
I construct what I term a double cell exactly upon the same principles as
above described for a single cell, but the width of the enclosure is increased to the
requisite extent and in addition to the two series of side shelves, I fix in the
centre of the space between the side shelves, a third series of shelves E, Figure 3,
the breadth of each of which is the sum of the width of two of the side shelves.
In this "double" cell, two sets of anode carbons are used and are suspended in
the spaces between each of the series of side shelves and the central series of
shelves. It is obvious that, in the same way, a triple or quadruple cell may be
constructed. In Figures 1 and 3 the corresponding parts are lettered the same
and Figure 3 only differs from Figure 1 in having two sets of anodes instead of
one, and between these two anodes, a third series of shelves.
In putting the cell into operation, the chloride solution is run into the cell until
the uppermost of the shelves is well covered. Mercury is then passed in and
falling upon the uppermost shelf of each series, it fills the depression to the
depth of about three eighths of an inch and then falls through the opening
at the further end to the next shelf below and so on until all the shelves are charged.
The supply of mercury is continued until the bottom of the cell is also covered
to the depth of about half an inch. Connection is now made between the sus-
pended carbons and the positive pole of an electric current and between the
mercury on cach shelf and the negative pole and also between
that on the bottom of the cell and the negative pole, the latter most con-
veniently by means of the iron pipe through which the amalgam is withdrawn
from the cell. The flow of mercury into the cell is continued in a constant stream

page_text: so regulated that the alkali metal amalgam flows out as rich in alkali metal as
it is possible practically to produce it whilst retaining perfect fluidity at the
temperature at which the cell is worked. The chlorine evolved passes from the
cell through the pipe provided for its escape.
Under ordinary circumstances the electric current flows freely through the
amalgam on the bottom of the cell to that on the series of shelves by means of
the constant stream falling from one to the other, but I prefer to place the metal
on each of the shelves in independent connection with the current.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that what
I claim is
1. The process for obtaining alkali metal amalgam and chlorine by electrolysis,
which consists in exposing a plurality of superposed thin horizontal layers of
slowly moving mercury forming the cathode placed around or beside and in close
proximity with the approximately vertical anode, feeding the mercury slowly
through these cathode shelves in such manner that it shall arrive at the exit
with the requisite maximum concentration, substantially as described.
2. In a cell for electrolytic decomposition of solutions of alkaline chlorides, the
combination of a substantially vertical anode and a plurality of horizontal super-
posed shallow trays surrounding or closely contiguous to the same, each shelf or
each shelf and the bottom of the cell carrying a thin and widely extended layer
of mercury, whereby a very large amount of cathode surface of mercury can be
placed around the anode and the escape of the chlorine from the anode is not
impeded as it is from the under side of the anode surface when it is horizontal
and all necessity for moving parts or agitating mechanism is obviated.
3. The general arrangement and construction of electrolytic cell, substantially
as and for the purposes described.