An Improved Electrolytic Apparatus for the Production of Alkali.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
An Improved Electrolytic Apparatus for the Production of Alkali.
I, WILLIAM THOMSON, Baron Kelvin of Largs, Professor of Natural Philosophy
in the University of Glasgow, North Britain, do hereby declare the nature of
this invention to be as follows:-
This invention is of an improved apparatus for the production of alkali by the
electrolysis of sodium chloride or other salt with mercury to receive the sodium
(or other metallic base) and water to dissolve out this metal with evolution of
hydrogen. For brevity I shall speak of sodium and common salt, or simply salt,
on the understanding that other analogous salts, such as potassium chloride may
be used in the process to be described.
My apparatus consists of a rectangular trough, which may be twenty or thirty
centimetres deep, with a partition parallel to two of its sides dividing it into
two rectangular cells. In the bottoms of the two cells are fixed a large number
of transverse partitions and barricades, each of which may be half a centimetre
or a centimetre high. In a model apparatus which I have constructed, one cell
has five equidistant partitions mercury-tight at their ends next the side and the
partition dividing the compartment into six equal pools for mercury. In the
middle of each pool a barricade is fixed with one end mercury-tight at the par-
tition and leaving an opening of half a centimetre between the other end and the
side. The other cell has six partitions mercury-tight at their ends touching the
partition and side and each in line with one of the barricades of the first cell.
Thus the second cell is divided into seven pools for mercury. The first and last
of these pools are of half the breadth of the remaining five of this cell and of cach
of the six of the first cell. Each of the five wide pools of the second cell has a
barricade, mercury-tight at the end next the partition and leaving half a centi-
metre between the other end and the side of the cell. The bottoms of all the
pools are in one plane, except that of one of the end pools of the second cell, which
is about two millimetres deeper than the others. By an automatic arrangement
a ladle lifts mercury up from this pool to a height of a few millimetres and lets
it run by a long canal, which may be the handle of the ladle, over the tops of
cross-partitions and barricades, into the pool at the other end of the cell.
Twenty four holes are bored in the bottom near the ends next the partition of
the half pools of the first cell and of the narrow pools and half pools of the
second cell. These holes are connected two and two, by mercury-tight tunnels
below the bottom of the pools. Twelve of the holes, or all the twenty four, are
guarded by tubular lips rising about two millimetres from the bottom, to prevent
any of the pools from being wholly emptied of mercury.
In the use of the apparatus the bottom of each of the pools is always covered
with mercury to some depth less than the height of the transverse partitions and
barricades. When mercury is lifted by the ladle from the one end and allowed
to run into the narrow pool at the other end, it runs through the tunnels under
the main partition, zig-zagging round the ends of the barricades, and quickly

page_text: finds its level in each pool, which may be different in the different pools. This
process may possibly with advantage be quickened by placing the main trough
with one end somewhat higher than the other end.
The first cell contains salt solution over the mercury with carbons to serve as
anodes in the electrolytic process, which is carried out by connecting the positive
electrode of a generator of electricity with these carbons and the negative electrode
with the mercury.
The second cell contains water over the mercury which becomes alkaline by the
dissolution of sodium out of the mercury. This part of the process is promoted
by iron or carbon electrodes placed in the alkaline liquid and metallically con-
nected with the mercury.
A gas-tight cover over all and appliances to draw off chlorine and hydrogen
separately from above the liquids of the two cells; and appliances for introducing
strong salt solutions into the first and drawing off portions weakened by the
electrolysis, and for admitting fresh water into, and removing alkaline solution
from the second cell are wanted to complete the apparatus.
00
1
1000
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Patent Agents.
An Improved Electrolytic Apparatus for the Production of Alkali.
I, WILLIAM THOMSON, Baron Kelvin of Largs, Professor of Natural Philosophy
in the University of Glasgow, North Britain, 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:-
This invention is of an improved apparatus for the production of alkali by the
electrolysis of sodium chloride or other salt with mercury to receive the sodium
(or other metallic base) and water to dissolve out this metal with evolution of
hydrogen. For brevity I shall speak of sodium and common salt, or simply salt,
on the understanding that other analogous salts such as potassium chloride may
be used in the process to be described.
In order that my invention may be properly understood and readily carried
into effect, I have hereunto appended two sheets of drawings, of which,
Figure 1 is a plan, Figure 2 a cross section on the line x, x.
Figure 1 is a section on the line y, y, Figure 1.
Figure 3 is a section on the line 2, z, with ladle not in section.
Figure 4 is an end view.
My apparatus consists of a rectangular trough, which may be ten or twenty
centimetres deep, with a partition P, parallel to two of its sides R, S, dividing it
into two rectangular cells, which I shall call A and B for brevity. In the bottom
of A and B are fixed a large number of transverse partitions a and barricades b,
each of which may be a centimetre high or more. In the apparatus shown, cell A
has four equidistant partitions, mercury-tight at their ends next R and P,
dividing the compartment into five equal pools for mercury, In the middle of
cach pool a barricade b is fixed with one end mercury-tight at P and leaving an
opening of half a centimetre between the other end and R. Cell B has five par-
titions, mercury-tight at their ends touching P and S, and each in line with one
of the barricades of A. Thus cell B is divided into six pools for mercury.
breadths at P of the first and sixth pools of B are half the breadth of the pools
of A. The breadth at P of the other four pools of B are all the same as those of A. Į
The

page_text: The shapes of the fifth and sixth pools of B are altered by the slanting of the fifth
partition as shown on the drawings for the purpose of giving space for the ladle
at one end of the sixth pool F. Each of the four wide pools of B has a barricade,
mercury-tight at the end next P and leaving about half a centimetre between the
other end and S. The bottoms of all the pools are in one plane, except that of F,
the sixth pool of cell B, which has a well at the end next S into which a ladle
dips. By a mechanical arrangement, shown at Figure 3, the ladle lifts mercury
up from F to a height of a few centimetres and lets it run by a long canal G over
the tops of cross-partitions and barricades, into E.
Passages are formed between cell A and cell B at the places marked c under-
neath the partition P to allow the mercury to flow backwards and forwards from
one compartment to the other. One of these passages is shown at Figure 1.
For emptying the apparatus holes are made from below into each of the
passages and are plugged by conical india-rubber corks, carried on a transverse
bar C which can be raised or lowered to close or open the holes. The ends e of
the transverse bar C very slightly rounded as shown in Figure 2 so as to press
the walls only at one or other of the upper sides of its ends are guided against
horizontal motion by the vertical walls V and W below the bottom, and by small
guiding pieces fixed to these walls but not shown in the drawings. A play of
half a millimetre of horizontal motion from right to left between the walls and
from front to back between the other guides may be allowed to prevent jamming.
The bar C is made one side of a rectangular frame with two sides M, M, projecting
to a fulcrum f, f, attached to a transverse wall projecting below the far edge of
the bottom. The near side of this rectangle is shown at L, L, Figure 4. To
press the corks into position, the side L, L, of the rectangular frame is pulled and
held up by a link /, Figure 4, which may be let down to open the holes. It may
be let down far enough to free the ends of the transverse bar C from the guiding
pieces and then it may be removed altogether so as to leave the main cells con-
veniently free for cleaning out their bottoms through the holes h. The corks are
fixed to the upper side of the bar C in the manner shown at Figure 2. By taking
out the screws u the upper plate T is free to be removed carrying the corks with
it and fresh corks may be put in at any time with perfect ease.
In the use of the apparatus the bottom of each of the pools is always covered
with mercury to some depth less than the height of the transverse partitions and
barricades. When mercury is lifted by the ladle from F and allowed to run
into E, it runs through the passages under the main partition, zig-zagging round
the ends of the barricades, and quickly finds its level in each pool, which may be
slightly different in the different pools. This process may possible with advantage
be quickened by placing the main trough with the side V, V, somewhat higher
than the side W, W.
Cell A contains salt solution over the mercury with carbons to serve as anodes
in the electrolytic process, which is carried out by connecting the positive electrode
of a generator of electricity with these carbons and the negative electrode with the
mercury.
Cell B contains water over the mercury which becomes alkaline by the dis-
solution of sodium out of the mercury. This part of the process is promoted by
iron or carbon electrodes placed in the alkaline liquid and metallically connected
with the mercury.
An iron cover D, corrugated to give increased surface with holes at the top
of each bend to allow bubbles of hydrogen to escape into the air with as little
sputtering of the liquid as possible, is placed over the bottom of the cell B. This
cover is supported above the mercury on glass or earthenware support. which may
conveniently be the tops of the barricades and partitions, and is metallically con-
nected to a pool of mercury H outside the trough connected by a passage through
the side of the trough with the mercury inside. The mercury pool H is con-
nected with the negative electrode. The connection of the iron with the mercury H

page_text: may be as shown in Figure 2 or it may be through any apparatus for using part
of the energy of the combination of the sodium and oxygen and avoiding unneces-
sary or injurious generation of heat in the cell.
A gas-tight cover over the cell A and an appliance to draw off chlorine; and
appliances for introducing strong salt solutions into A and drawing off portions
weakened by the electrolysis, and for admitting fresh water into, and removing
alkaline solution from B, are wanted to complete the apparatus.
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:-
The apparatus for the production of alkali consisting of a trough divided into
two cells, each cell divided into pools and mercury caused to flow through these
pools in succession, as described and illustrated by the drawings.
Dated this 29th day of May 1899
BOTTOMLEY & LIDDLE,
154, St. Vincent Street, Glasgow, Applicant's Patent Agents.