An Improved Process of and Apparatus for the Electrolytic Decomposition of Alkaline Salts.
Year: 1892

page_text: Date of Application, 7th Sept., 1892
Complete Specification Left, 6th June, 1893-Accepted, 15th July, 1893
PROVISIONAL SPECIFICATION.
An Improved Process of and Apparatus for the Electrolytic
Decomposition of Alkaline Salts.
I HAMILTON YOUNG CASTNER of 115 Cannon Street in the City of London
Managing Director of The Aluminium Company Limited do hereby declare the
nature of this invention to be as follows:-
This invention has for its object the economical electrical decomposition of
alkaline salts in solution or otherwise and is particularly applicable to the
production of pure alkaline hydrates, and chlorine or hypochlorites from alkaline
chlorides.
The electrical decomposition of haloid compounds of the alkali metals for the
production of the corresponding halogens and alkaline hydrates has long been
known, but, so far as I am aware, has never been commercially carried on for one
or more of the following reasons:-
1st. The required use of a porous partition or diaphragm to separate the
electrodes and the consequent products of the electrolysis necessarily interposes a
considerable electrical resistance. Such electrical resistance increases relatively
to the effectiveness of the chemical separation.
2nd. As the chemical separation has never been perfect in a single cell, the
intermingling of the two products of the electrical decomposition gives rise to a
new series of products, which more or less interfere with the continuance of the
electrical action besides meaning a direct loss in current efficiency,
3rd. The caustic solutions produced contain more or less salt and are very
dilute
as the strong solutions more rapidly diffuse through the porous partition or
diaphragm. Thus pure caustic cannot be obtained and the concentration and
production of solid caustic materially increases the manufacturing cost.
4th. In the various kinds of apparatus which have been designed to overcome
these many difficulties the parts are more or less complicated and thus both
expensive and almost impossible to work practically on a large scale.
The present invention consists of a process of and apparatus for producing
electrolytically from chloride of sodium, pure caustic soda and chlorine or hypo-
chlorites or when treating other materials obtaining analogous products. Briefly
stated the invention may be said to cousist in the employment of a mechanically
moving body of mercury or other liquid metal or alloy between the anode and
cathode compartments of a decomposing cell completely separating the materials
therein and so placed that the current in its passage through the cell, from the
actual anode to the actual cathode must pass into and through the moving metal:
Thus while the alkaline metal is being deposited in such liquid metal in the anode
compartment a like amount of the alkali metal is being set free in the cathode
compartment thereby reducing the counter electromotive force, rendering it
possible to carry on the electrical action continuously with a very. high current
efficiency and yielding at the same time where water is used in the cathode
compartment a solution of pure caustic of any desired strength.
Practically the moving liquid metal takes the place of a diaphragm and without
interposing any appreciable resistance to the passage of the current it completely
separates the products of the electrolysis. At the same time it allows the
intervening space between the positive and negative electrodes to be reduced to
a minimum and yet to have such space effectively occupied by salt and caustic
solution.

page_text: In the accompanying drawings
Figs. 1 and 2 illustrate by sectional elevation and plan a simple form of
electrolytic cell or apparatus with two compartments.
Figs. 3 and 4 illustrate by sectional elevation and plan a three compartment
apparatus or cell which will be found must suitable for carrying out the process on
a commercial scale.
In Figs. 1 and 2 the square cell A is divided by an impervious partition B into
two chambers A' A². The lower part of the cell is circular at D and the bottom
is closed by metal plate E beneath which is a hollow chamber or water jacket F
served by pipes G G through which water or other cooling medium is caused to pass.
The electrical connection from bottom plate E is marked E'.
Through partition B passes a spindle H fitted at the bottom with radial helical
blades I and at the top with a driving pulley K.
The negative electrodes L are clamped together and hung in chamber A¹ to
which is secured the connection M.
The positive electrode N passes into chamber A² and is joined to connection N¹
having two branches N2 N3.
shown at O.
Partition B is provided with a metal shoe at B' but such shoe does not touch
the bottom of the cell. Mercury or other metal or alloy in a fluid state is
Compartment A is provided with an outlet governed by tap P while the outlet
for liquid from A2 is indicated by Q and for gas by R and the inlet for liquid into
A' by S. Both chambers or compartments are covered by glass or other plates T.
In Figs. 3 and 4 of the drawings the cell A has two partitions B B making
three chambers A' A² A³ communicating at the bottom which is closed with metal
casting C having channels D' D².
In the metal bottom E are three barrels or cylinders having pistons I moved by
rod in any convenient way. Mercury is drawn into and expelled from alternate
ends of the cylinders causing circulation from cell A' to A' and from A to A³ or
from A³ to A' and from A' to A alternately.
Bottom plate C has the connection E' fastened on it and a hollow water jacket F
is provided for cooling purposes, the water for which enters and leaves by
pipes G G¹.
Plates L are clamped together and supported in chamber A¹ and are in
connection with wire M.
The positive electrodes NN project into chambers A² A' and are joined to
connections N¹ having branches N° Ñ³.
The partition walls B B have metal shoes B B along the bottom
into mercury in channels D D in which the mercury level is shown are dipping |
0.
The outlet from A' is provided with a tap at P while the outlet from A² and A³
for liquid is indicated by Q and for gas by R while the liquid inlet is indicated
by S the chambers having glass or other suitable covers T.
The operations of the process as carried on in the cell illustrated by Figs. 1
and 2 being most easily understood are first described. The cell being charged
with mercury up to the level O as shown, this forms with the aid of the partition B
and the metal shoe B' which is directly amalgamated by the mercury a complete
means of separating the solutions placed therein. Compartment A' is charged
with water and A with a saturated solution of salt. The stirrer I is started
slowly revolving and water is passed through compartment F by means of pipes G
and G. In carrying on the process it is necessary that the mercury should always
contain a certain proportion of sodium. Should sodium not be present in the
mercury, on the passage of the current through the cell, in the compartment A',
hydrogen and oxygen will be set free, the hydrogen passing off, the oxygen
combining with the mercury. In the presence of sodium however no mercury
is oxidized but the contained sodium being oxidized goes in solution as
caustic. Thus to prevent the oxidation of the mercury and maintain the proper
electrical and chemical action it is absolutely necessary that the alkali metal must

page_text: always be present in the mercury; the fixed quantity being more or less regulated
by the means employed for stirring. If the electrical efficiency of the passing
current through this cell could be maintained at 100 per cent. in both compartments
then starting with mercury containing a small proportion of sodium, the quantity
would remain constant, the chloride would be decomposed in A², chlorine being
liberated and amalgam forming, while in A' hydrogen is set free, the sodium going
in solution as caustic. From experiment I judge that it will be impossible to
obtain 100 per cent. efficiency in the passing of the current through A² owing to
the partial decomposition of water or, what amounts to the same thing, owing
to the deposited sodium recombining with the chlorine present to form chloride, or
with the water to form caustic and consequently hypochlorite. This loss in
efficiency will increase relatively with the percentage of sodium in the amalgam
being used and also with any rise in temperature during the electrolysis. With
proper stirring and regulated electrical action the amalgam can be kept at a
uniform strength containing a minimum amount of sodium, and any increase of
temperature due to the passage of the current may be prevented by the cold
water flowing through F. Practically by this process and similar apparatus an
efficiency of 90 per cent. can be obtained.
As the electrical efficiency in compartment A' is always 100 per cent., to ensure
the presence of sodium in the mercury I proceed as follows, best explained by the
following examples. The wires N' and E' are connected with the terminals of a
dynamo and the current passed therefrom causes sodium to be deposited in the
mercury and this is continued until an amalgam containing about 2 % (two tenths
of one per cent.) of sodium is obtained. Then N³ and M are made the connecting
wires between the dynamo and the anode N and cathode L, the current passing for
example being 90 amperes. N2 and E' are also connected with the positive and
negative poles respectively of a second dynamo which supplies a current of
10 amperes. Thus while 100 amperes are passing through N only 90 are passing
through M and the amalgam will remain at 2% (two tenths of one per rent.) of
sodium while 90 per cent. of the theoretical yield for the combined or total current
will be obtained as caustic in A¹ and a corresponding amount of chlorine will be
produced in A². Without employing two sources of current the same result may
be obtained by passing the current say for one hour using the wires E and N¹ and
then changing and for nine hours using N1 and M as the connections for the supply
of the same current. Thus cells coupled in series have their connections so
arranged as to allow this change to be made in turn and so allow a number of cells
to be worked without varying the total difference of potential in the dynamo
terminal. It is evident that cells coupled in parallel necessitate the use of two
currents to maintain the presence of sodium in the mercury; the efficiency yield
determining the proportion existing between the two currents. With cells coupled
in series a single current only is required, the direction of passage through the cell
being changed by time as fixed also by the efficiency.
After charging and starting the apparatus as before mentioned the current being
passed as described in either of the foregoing examples, chlorine is given off in
compartment A and escapes through the opening R into any suitable collecting
apparatus. The solution which is kept at saturation, by the addition of salt from
time to time, may be removed and replaced by a fresh solution free from hypo-
chlorites when necessary, while the solution so removed is treated either to separate
or decompose the hypochlorite and then again returned to the cell, or if desired
this operation may be made continuous. Some advantage is also gained by
employing salt solutions free of calcic sulphate an impurity always occurring in
common salt.
Unless it is removed from the solutions the proportion of this
impurity gradually increases to such an extent as to materially decrease the current
efficiency.
The oxidation and solution of the sodium in the cell generates a certain amount
of electrical energy or practically the electromotive force necessary to decompose

page_text: "
:
•
'
sodium chloride into its elements less the electromotive force gained by the
oxidation and solution of the metal to caustic and represents the actual counter
electromotive force of the cell. A result being equivalent to the direct electrolysis
of sodium chloride solution into caustic soda, hydrogen, and chlorine, with the
advantage of separating the products completely by the interposition of a substance
that offers no appreciable electrical resistance and allows the electrodes to be
brought almost in direct contact. At the commencement of the operation owing
to the weak caustic solution in A' being a poor electrical conductor the resistance
will be high but as this solution becomes concentrated the electrical resistance will
fall considerably. In running continuously after the solution in A¹ reaches a
certain strength it is kept so by allowing water to How slowly into the compartment,
in proportion to the caustic being produced, while a uniform strength caustic
solution is being drawn off at P. In this way without disturbing the liquid level
of the compartment a continuous flow of caustic solution is maintained.
In Figs. 3 and 4 which represent a larger and more economical apparatus the
same principle is employed the advantages being in the double compartment for
salt solution, the comparatively small quantity of mercury needed and the improved
method of keeping the mercury in motion. The three compartments shown are the
same size the depth of mercury, being about th of an inch. Thus the same weight
of mercury is in each compartment and the combined capacity of the three small
piston pumps I is made equal at a single stroke to the space occupied by the
mercury in each compartment. For example, if the size of a cell requires for a
depth of th of an inch 30 lbs. of mercury or 10 lbs. per compartment then the
combined capacity of the three small pumps per stroke is made 10 lbs. and in
reality 40 lbs. of mercury is used in each complete cell. At each stroke of the
three pumps which move very slowly the mercury or amalgam completely changes
its position and as the pumps are moving constantly during the electrolysis the
mercury is continuously flowing from an anode compartment into a cathode com-
partment and vice versa. The carbons which are used as anodes slowly disintegrate
and may be moved inwards as required, new ones being substituted from time to
time. The solutions are treated as before mentioned. The strong caustic liquor.
being evaporated produces pure caustic soda, a product at present unknown in
commercial quantities. The above arrangement of apparatus and parts thereto are
described merely to fully illustrate the process and the character of the apparatus
necessary to carry out the idea of a moving body of liquid metal as the means of
separating the two solutions in an electrolytic cell during electrolysis, completely
doing away with a porous diaphragm of any kind heretofore always thought
necessary in similar electrical processes.
"
In the foregoing when mention of sodium chloride is made it is apparent that
⚫ potassium chloride could be substituted. It is also apparent that the process and
apparatus is adapted to the formation of other salts as well as hydrate according to
the treatment in the cathode compartment, that instead of chloride of the alkali
metals being used, other salts of the alkali metals may be substituted in the anode
compartment, that hypochlorites may be formed directly in the anode compartment
instead of allowing the chlorine to escape. That in place of carbon anodes any
other suitable material capable of resisting the action of chlorine may be substituted
and that the same principle may be applied to the electrolysis of fesed salts using a
molten metal such as lead, tin or the like or an alloy of various metals in place of
mercury. It has long been known that sodium amalgam can be made by electro-
lyzing a solution of the hydrate or chloride using mercury as a cathode.
It is
also evident that to produce a rich amalgam (say to 1 per cent.) the mercury
must be stirred else a large part of the sodium deposited on the surface of the
mercury would be oxidized and return to the solution actually meaning a loss in
efficiency.
1.
I am aware that various and special means have been suggested for producing
amalgams and then by subsequent and separate treatment to produce caustic and

page_text: mercury for re-use but such suggestions can only refer to a distinct form of
apparatus to carry out a process long known of using mercury as a cathode.
Dated the 7th day of September 1892.
PHILIP M. JUSTICE,
Chartered Patent Agent, 55 & 56, Chancery Lane, London,
For the Applicant.
COMPLETE SPECIFICATION.
An Improved Process of and Apparatus for the Electrolytic
Decomposition of Alkaline Salts.
HAMILTON YOUNG CASTNER formerly of 115 Cannon Street but now of
13 and 14 Abehurch Lane in the City of London, Managing Director of The
Aluminium Company Limited 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 has for its object the economical electrical decomposition of
alkaline salts in solution or otherwise and is particularly applicable to the pro-
duction of pure alkaline hydrates, and chlorine or hypochlorites from alkaline
chlorides.
The electrical decomposition of haloid compounds of the alkali metals for the
production of the corresponding halogens and alkaline hydrates has long been
known, but, so far as I am aware, has never been commercially carried on for one
or more of the following reasons:-
1st. The required use of a porous partition or diaphragm to separate the
electrodes and the consequent products of the electrolysis necessarily interposes a
considerable electrical resistance. Such electrical resistance increases relatively to
the effectiveness of the chemical separation.
2nd. As the chemical separation has never been perfect in a single cell, the
intermingling of the two products of the electrical decomposition gives rise to a
new series of products, which more or less interfere with the continuance of the
electrical action besides meaning a direct loss in current efficiency.
3rd. The caustic solutions produced contain more or less salt and are very dilute
as the strong solutions more rapidly diffuse through the porous partition or
diaphragm. Thus pure caustic cannot be obtained and the concentration and
production of solid caustic materially increases the manufacturing cost.
4th. In the various kinds of apparatus which have been designed to overcome
these many difficulties the parts are more or less complicated and thus both
expensive and almost impossible to work practically on a large scale.
The present invention consists of a process of and apparatus for producing
electrolytically from chloride of sodium, pure caustic soda and chlorine or hypo-
chlorites or when treating other materials obtaining analogous products. Briefly
stated the invention may be said to consist in the employment of a mechanically
moving body of mercury or other liquid metal or alloy between the anode and
cathode compartments of a decomposing cell completely separating the materials
therein and so placed that the current in its passage through the cell, from the
actual anode to the actual cathode must pass into and through the moving metal.
Thus while the alkaline metal is being deposited in such liquid metal in the anode
compartment a like amount of the alkali metal is being set free in the cathode
compartment thereby reducing the counter electromotive force, rendering it
possible to carry on the electrical action continuously with a very high current
efficiency and yielding at the same time where water is used in the cathode
compartment a solution of pure caustic of any desired strength.
Practically the moving liquid metal takes the place of a diaphragm and without
interposing any appreciable resistance to the passage of the current it completely

page_text: *separates the products of the electrolysis. At the same time it allows the inter-
vening space between the positive and negative electrodes to be reduced to a
minimum and yet to have such space effectively occupied by salt and caustic
solution.
In the drawings accompanying the Provisional Specification
Figs. and 2 illustrate by sectional elevation and plan a simple form of
electrolytic cell or apparatus with two compartments.
Figs. 3 and 4 illustrate by sectional elevation and plan a three compartment
apparatus or cell which will be found most suitable for carrying out the process on
a commercial scale.
In Figs. 1 and 2 the square cell A is divided by an impervious partition B into
two chambers A' A². The lower part of the cell is circular at D and the bottom
is closed by metal plate E beneath which is a hollow chamber or water jacket F
served by pipes G G through which water or other cooling medium is caused
to pass.
The electrical connection from bottom plate E is marked E¹.
Through partition B passes a spindle H fitted at the botton with radial helical
blades I and at the top with a driving pulley K.
The negative electrodes L are clamped together and hung in chamber A' to
which is secured the connection M.
The positive electrode N passes into chamber A2 and is joined to connection N'
having two branches N2 N3.
Partition B is provided with a metal shoe at B' but such shoe does not touch
the bottom of the cell. Mercury or other metal or alloy in a fluid state is
'shown at O.
Compartment A' is provided with an outlet governed by tap P while the outlet
for liquid from A' is indicated by Q and for gas by R and the inlet for liquid
into A by S. Both chambers or compartments are covered by glass or other
plates T.
In Figs. 3 and 4 of the drawings the cell A has two partitions B B making three
chambers A A A³ communicating at the bottom which is closed with metal
casting Chaving channels D' D².
In the metal bottom E are three barrels or cylinders having pistons I moved by
rod in any convenient way. Mercury is drawn into and expelled from alternate
ends of the cylinders causing circulation from cell A² to A¹ and from A¹ to A³ or
from A³ to A and from A' to A alternately.
Bottom plate C has the connection E¹ fastened on it and a hollow water jacket F
is provided for cooling purposes, the water for which enters and leaves by
pipes G G¹.
Plates L are clamped together and supported in chamber A' and are in
connection with wire M.
The positive electrodes N N project into chambers A² A³ and are joined to
connections N¹ having branches N³ N³.
The partition walls B B have metal shoes B' B¹ along the bottom edge dipping
into mercury in channels D¹ D2 in which the mercury level is shown at O.
The outlet from A' is provided with a tap at P while the outlet from A' and A³
for liquid is indicated by Q and for gas by R while the liquid inlet is indicated
by S the chambers having glass or other suitable covers T.
The operations of the process as carried on in the cell illustrated by Figs. 1 and 2
being most easily understood are first described. The cell being charged with
mercury up to the level O as shown, this forms with the aid of the partition B
and the metal shoe B₁ which is directly amalgamated by the mercury a complete
means of separating the solutions placed therein. Compartment A¹ is charged
with water and A2 with a saturated solution of salt. The stirrer I is started
slowly revolving and water is passed through compartment F by means of pipes G
and G. In carrying on the process it is.necessary that the mercury should always
contain a certain proportion of sodium. Should sodium not be present in the

page_text: mercury, on the passage of the current through the cell, in the compartment A',
hydrogen and oxygen will be set free, the hydrogen passing off, the oxygen com-
bining with the mercury. In the presence of sodium however no mercury is
oxidized but the contained sodium being oxidized goes in solution as caustic. Thus
to prevent the oxidation of the mercury and maintain the proper electrical and
chemical action it is absolutely necessary that the alkali metal must always be
present in the mercury; the fixed quantity being more or less regulated by the
means employed for stirring. If the electrical efficiency of the passing current
through this cell could be maintained at 100 per cent. in both compartments then
starting with mercury containing a small proportion of sodium, the quantity would
remain constant, the chloride would be decomposed in A, chlorine being liberated
and amalgam forming, while in A¹ hydrogen is set free, the sodium going in solution
as caustic. From experiment judge that it will be impossible to obtain
100 per cent. efficiency in the passing of the current through A² owing to the
partial decomposition of water or, what amounts to the same thing, owing to the
deposited sodium recombining with the chlorine present to form chloride, or
with the water to form caustic and consequently hypochlorite. This loss in
efficiency will increase relatively with the percentage of sodium in the amalgam
being used and also with any rise in temperature during the electrolysis. With
proper stirring and regulated electrical action the amalgam can be kept at a
uniform strength containing a minimum amount of sodium, and any increase of
temperature due to the passage of the current may be prevented by the cold water
flowing through F. Practically by this process and similar apparatus an efficiency
of 90 per cent, can be obtained."
As the electrical efficiency in compartment Al is always 100 per cent., to ensure
the presence of sodium in the mercury I proceed as follows, best explained by
the following examples. The wires N' and E are connected with the terininals of a
dynamo and the current passed therefrom causes sodium to be deposited in the
mercury and this is continued until an amalgam containing about 2% (two tenths of
one per cent.) of sodium is obtained. Then N³ and M are made the connecting
wires between the dynamo and the anode N and cathode L, the current passing
for example being 90 amperes. N2 and E¹ are also connected with the positive and
negative poles respectively of a second dynamo which supplies a current of
10 amperes. Thus while 100 amperes are passing through N only 90 are passing
through M and the amalgam will remain at 2% (two tenths of one per cent.) of
sodium while 90 per cent. of the theoretical yield for the combined or total current
will be obtained as caustic in A' and a corresponding amount of chlorine will be
produced in A². Without employing two sources of current the same result may
be obtained by passing the current say for one hour using the wires E' and N' and
then changing and for nine hours using N and M as the connections for the supply
of the same current. Thus cells coupled in series have their connections so arranged
as to allow this change to be made in turn and so allow a number of cells to be
worked without varying the total difference of potential in the dynamo terminal.
It is evident that cells coupled in parallel necessitate the use of two currents to
maintain the presence of sodium in the mercury; the efficiency yield determining
the proportion existing between the two currents. With cells coupled in series a
single current only is required, the direction of passage through the cell being
changed by time as fixed also by the efficiency
After charging and starting the apparatus as before mentioned the current being
passed as described in either of the foregoing examples, chlorine is given off in
compartment A² and escapes through the opening R into any suitable collecting
apparatus. The solution which is kept at saturation, by the addition of salt from
time to time, may be removed and replaced by a fresh solution free from hypo-
chlorites when necessary, while the solution so removed is treated either to separate
or decompose the hypochlorite and then again returned to the cell, or if desired
this operation may be made continuous. Some advantage is also gained by

page_text: employing salt solutions free of calcic sulphate an impurity always occurring in
common salt.
Unless it is removed from the solutions the proportion of this
impurity gradually increases to such an extent as to materially decrease the current
efficiency.
The oxidation and solution of the sodium in the cell generates a certain amount
of electrical energy or practically the electromotive force necessary to decompose
sodium chloride into its elements less the electromotive force gained by the
oxidation and solution of the metal to caustic and represents the actual counter
electromotive force of the cell. A result being equivalent to the direct electrolysis
of sodium chloride solution into caustic soda, hydrogen, and chlorine, with the
advantage of separating the products completely by the interposition of a substance
that offers no appreciable electrical resistance and allows the electrodes to be
brought almost in direct contact. At the commencement of the operation owing
to the weak caustic solution in A¹ being a poor electrical conductor the resistance
will be high but as this solution becomes concentrated the electrical resistance will
fall considerably. In running continuously after the solution in A¹ reaches a
certain strength it is kept so by allowing water to flow slowly into the compartment,
in proportion to the caustic being produced, while a uniform strength caustic
solution is being drawn off at P. In this way without disturbing the liquid level
of the compartment a continuous flow of caustic solution is maintained.
In Figs. 3 and 4 which represent a larger and more economical apparatus the
same principle is employed the advantages being in the double compartment for
salt solution, the comparatively small quantity of mercury needed and the improved
method of keeping the mercury in motion. The three compartments shown are
the same size the depth of mercury being about th of an inch. Thus the same
weight of mercury is in each compartment and the combined capacity of the three
small piston pumps I is made equal at a single stroke to the space occupied by
the mercury in each compartment. For example, if the size of a cell requires for
a depth of th of an inch 30 lbs. of mercury or 10 lbs. per compartment then the
combined capacity of the three small pumps per stroke is made 10 lbs. and in
reality 40 lbs. of mercury is used in each complete cell. At each stroke of the
three pumps which move very slowly the mercury or amalgam completely changes
its position and as the pumps are moving constantly during the electrolysis the
mercury is continuously flowing from an anode compartment into a cathode
compartment and vice versú. The carbons which are used as anodes slowly
disintegrate and may be moved inwards as required, new ones being substituted
from time to time. The solutions are treated as before mentioned. The strong
caustic liquor being evaporated produces pure caustic soda, a product at present
unknown in commercial quantities. The above arrangement of apparatus and
parts thereto are described merely to fully illustrate the process and the character
of the apparatus necessary to carry out the idea of a moving body of liquid metal
as the means of separating the two solutions in an electrolytic cell during electro-
lysis, completely doing away with a porous diaphragm of any kind heretofore
always thought necessary in similar electrical processes.
Since the date of this application I have also ascertained that the mercury or
amalgam can be satisfactorily caused to flow from compartment to compartment by
imparting a slight tilting or rocking movement to the cell and an arrangement
of apparatus for this purpose forms the subject of a separate application for
Letters Patent No. 10,584 dated 30 May 1893.
In the foregoing when mention of sodium chloride is made it is apparent that
potassium chloride could be substituted. It is also apparent that the process and
apparatus is adapted to the formation of other salts as well as hydrate according
to the treatment in the cathode compartment, that instead of chloride of the
alkali metals being used, other salts of the alkali metals
may be substi-
tuted in the anode compartment, that hypochlorites may be formed directly
in the anode compartment instead of allowing the chlorine to escape. That

page_text: in place of carbon anodes any other suitable material capable of resisting the
action of chlorine may be substituted and that the same principle may be
applied to the electrolysis of fused salts using a molten metal such as lead,
tin or the like or an alloy of various metals in place of mercury. It has long
been known that sodium amalgam can be made by electrolyzing a solution of the
hydrate or chloride using mercury as a cathode. It is also evident that to
produce a rich amalgain (say to i per cent.) the mercury must be stirred else a
large part of the sodium deposited on the surface of the mercury would be
oxidized and return to the solution actually meaning a loss in efficiency.
1
I am aware that various and special means have been suggested for producing
amalgams and then by subsequent and separate treatment to produce caustic and
mercury for re-use but such suggestions can only refer to a distinct form of
apparatus to carry out a process long known of using mercury as a cathode.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed declare that what I
claim is:-
1. In a process for the electrolytic decomposition of alkaline salts the employ-
ment of a moving body of a liquid metal or alloy to separate the anode and cathode
compartments of the decomposing cell and through which body of liquid metal or
alloy the current passes.
2. In a process for the electrolytic decomposition of alkaline salts the employment
of a liquid metal or alloy in the decomposing cell for the purpose of carrying the
alkaline metal from the anode to the cathode compartment.
3. In a process for the electrolytic decomposition of alkaline salts employing a
body of liquid metal or alloy circulating between the two compartments of the
decomposing cell through which the current is made to pass and so placed as to
act both as an anode and cathode.
4. In a process for the electrolytic decomposition of alkaline salts the employment
of a cell not only provided with the usual anode and cathode but also with a body
of moving liquid metal or alloy into, through, and from which the alkaline metal
is made to pass by combined electrical and mechanical means.
5. In a process for the electrolytic decomposition of alkaline salts the employment
of a body of liquid metal or alloy to prevent any recombination of the final products
of the electrolysis.
6. In a process for the electrolytic decomposition of alkaline salts the utilization
of the electrical energy stored in amalgams or alloys produced during said process
to reduce the counter electromotive force necessary for the production of such
alloys or amalgams.
7. In a process for the electrolytic decomposition of alkaline salts, employing
the electric current for decomposing the alkaline amalgams or alloys produced
therein.
8. In a process for the electrolytic decomposition of alkaline salts the continuous
production and decomposition of an alkaline amalgam or alloy by the electric
current ensuring the presence of the alkali metal in such amalgam or alloy by the
aid of a supplementary current passing through the anode compartment or other-
wise substantially as specified.
9. In an electrolytic apparatus the combination with the anode and cathode
compartments of a body of liquid metal or alloy forming part of the electrical
circuit and capable of being moved from one compartment to the other substantially
as set forth.
10. In an electrolytic apparatus the combination with the anode and cathode
compartments of a body of metal or alloy forming part of the electrical circuit
with means for mechanically causing such liquid metal or alloy to circulate between
the said compartments substantially as set forth.
11. In an electrolytic apparatus the combination of an anode and cathode with

page_text: a moving body of liquid metal or alloy so placed as to separate the materials
either placed or being produced in the two compartments of the decomposing cell
substantially as set forth.
Dated the 6th day of June 1893.
PHILIP M. JUSTICE,
55 & 56, Chancery Lane, London,
Chartered Patent Agent for the Applicant.