Improvements in and Apparatus for the Manufacture of Alkaline or Earthy Alkaline Bases and of their Salts or Compounds by the Electrolysis of Saline Solutions.
Year: 1891

page_text: Date of Application, 15th Dec., 1891
Complete Specification Left, 14th Sept., 1892-Accepted, 29th Oct., 1892
PROVISIONAL SPECIFICATION.
Improvements in and Apparatus for the Manufacture of Alkaline
or Earthy Alkaline Bases and of their Salts or Compounds by
the Electrolysis of Saline Solutions.
We, EUGENE HERMITE and ANDRE DUBOSC both of 4 Rue Drouot, Paris in
the Republic of France Manufacturers do hereby declare the nature of this inven-
tion to be as follows:-
It is known that when an electric current is caused to pass through a solution of
a salt of any alkaline or earthy alkaline base, the acid and the oxygen combined
with the metal of the base pass to the positive pole and the metal passes to the
negative pole. A certain amount of water is generally decomposed at the same
time. The metal decomposes the water of the bath and becomes converted into
oxide setting hydrogen free.
The same theory applies to haloid salts such as chlorides. The chlorine and the
oxygen resulting from the decomposition pass to the positive. pole and the base is
reconstituted at the negative pole.
Attempts have been made to utilise this principle in order to separate alkaline
and earthy alkaline bases such as potash and caustic soda for example from their
saline combinations but it is necessary to provide for separating the base from the
acid as fast as the salt is decomposed in order to withdraw it from the influences of
the acid and of the current and obviate recombination of the separated elements.
With this object it has been proposed to employ electrolysing apparatus divided
into two compartments by porous or permeable membranes or partitions the base
being collected in the compartment containing the negative electrode and the acid
or oxygenised chlorine compound in the other but this method of operating is
attended with serious disadvantages in practice.
Another method is based on the employment of mercury in order to effect the
separation of the base. In this case the bottom of the electrolysing vessel is covered
with a layer of mercury electrically connected with the negative pole of the
generator the positive electrode being immersed in the saline solution which stands
upon the mercury.
As fast as the salt is decomposed the metal of the base passes to the negative
pole constituted by the mercury and forms an amalgam with the latter. The acid
or oxygenised chlorine compound remains in the saline solution.
It is not possible to work the process successfully in practice with this arrange-
ment. In proportion as the percentage of metal in the amalgam increases the
metal, being in the presence of the saline solution, is decomposed by the latter so
that after a short time the increase of amalgam is arrested and the current is
expended to no purpose.
Now according to our invention the amalgam is automatically removed as fast as
it is formed, from contact with the saline solution and from the influence of the
électric current and is continually replaced by fresh or non amalgamated mercury.
With this object we utilise the difference of density or weight between the
amalgam aud the mercury and arrange the apparatus so that the richest amalgam
is removed and brought into contact with the water or the acid by which it is
decomposed in order to form the required product and the lower layers of
"disamalgamated" mercury are returned and exposed to the action of electrolysis
in the presence of the saline solution in order to reform the amalgam which is again
removed from the action of the electric current and saline solution as fast as it is
formed and is separated from the mercury owing to its lesser specific gravity the
operation being automatically conducted in a regular and continuous manner by
pure or

page_text: the aid of any suitable combination of apparatus such for example as that herein-
after described.
An apparatus for the manufacture of caustic soda for example according to this
invention may be constructed as next hereinafter described for example and it is evident
that apparatus constructed on the same principle may likewise be employed for
operating on a solution of any salt of an alkaline or earthy alkaline base such as
potash, soda, ammonia, magnesia alumina and the like either for the purpose of
separating the base from the salt or with the object of obtaining another saline
solution. In the former case the amalgam formed is decomposed by water and in
the second case by any suitable acid. In order to obtain a carbonate for example
a current of carbonic acid is passed through the water employed to decompose the
amalgam.
The solution to be electrolysed is contained in one vessel and the water employed
to separate the sodium from the amalgam in order to obtain the caustic soda is
contained in another vessel. This water may be heated in order to accelerate the
reaction.
The two electrodes are immersed in the saline solution. The negative electrode
is constituted by one or more inclined plates or sheets of metal amalgamated on the
upper surface in order to cause the mercury to flow smoothly down the same in
place of rolling down in the form of globules. At their lower extremities these
plates are bent upwards so as to form shoots or gutters for the reception of the
amalgam formed by the electrolytic action. The positive electrodes made of
platinum or other suitable metal are placed in an inclined position over and facing
the negative electrodes so that the mercury passes between the position and
negative electrodes. It is evident that the Hat plates may be replaced by other
inclined surfaces of conical curved or other form. The mercury is supplied to the
upper part of the electrodes by means of a distributer in the form of a. horizontal
trough communicating with a series of short tubes or nozzles arranged. to deliver
the mercury in such a manner as to cause it to spread uniformly over the surfaces
of the plates or inclined surfaces.
The arrangements for enabling the mercury to circulate continuously through
the apparatus comprises a combination of tubes one of which connects the gutter or
receptacle for the amalgam in the electrolysing vessel with the vessel containing
the water herein before referred to or separating vessel the said pipe is arranged at
such a level as to draw off the richest or uppermost part of the amalgam and is
provided with a Ụ shaped bend for the purpose of preventing the liquid or solution
in the electrolysing vessel from passing into the separating vessel. The gutter
receiving the amalgam from.the electrodes is also connected at the bottom or lowest
part where the purer part of the mercury collects owing to its greater weight, with
a receptacle from which this mercury is returned to the upper part of the
electrolysing vessel. This receptacle also communicates through a pipe with the
mercury at the bottom of the separating vessel. Both of these pipes are provided
with suitable bends for maintaining the desired level of mercury in the several
vessels and the mercury which they deliver into the receptacle is returned to the
distributing trough at the upper part of the electrolysing vessel by means of a
chain pump or other suitable elevating apparatus.
In working with this apparatus the mercury flows in a thin film or layer down
the inclined surface of the negative electrode in contact with the saline solution in
the space between the mercury and the positive electrode. This mercury becomes
charged with the sodium resulting from the electrolytic decomposition of the saline
solution and is collected in the gutters at the lower part of the electrodes where it
is.no longer acted on by the current.
In order to protect the mercury in the gutter from contact with the saline solution
the upper part of the gutter is filled with. sulphuret. of carbon or any other liquid
which is lighter than the amalgam and heavier than the solution.
In this gutter the contents, arrange themselves in order of gravity the purest and
heaviest part of the mercury' collecting at the bottom whence it is drawn off through

page_text: the pipe communicating with the receptacle from which it is returned to the electro-
lysing vessel whilst the richer part or amalgam floats at the top and passes through
the other pipe to the separating vessel the sulphuret of carbon being prevented
from escaping into the separating vessel by the U shaped bend in the pipe which
is so adjusted as to maintain a column of mercury in such a manner as to balance
the pressures and maintain the required levels in the respective vessels.
The body of amalgam in the separating vessel arranges itself in order of density
the richer part floating at the top in direct contact with the water which decomposes
it and takes up the sodium to form the caustic soda whilst the pure mercury sinks
to the bottom and flows away through the pipe to the receptacle whence it is
returned to the electrolysing vessel and thus circulates regularly and continuously
through the apparatus the operation being continued without intermission.
Caustic soda potash or ammonia of any desired degree of concentration may be
obtained in the separating vessel according to the duration of the operation and the
soda for example may be drawn off through a cock placed at the lower part of the
vessel above the level of the mercury or amalgam.
Dated this 15th day of December 1891
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents.
COMPLETE SPECIFICATION.
Improvements in and Apparatus for the Manufacture of Alkaline
or Earthy Alkaline Bases and of their Salts or Compounds by
the Electrolysis of Saline Solutions.
We, EUGENE HERMITE and ANDRE DUBOSC both of 4 Rue Drouot, Paris in
the Republic of France, Manufacturers, 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 :-
It is known that when an electric current is caused to pass through a solution of
a salt of any alkaline or earthy alkaline base, the acid and the oxygen combined
with the metal of the base pass to the positive pole and the metal passes to the
negative pole. A certain amount of water is generally decomposed at the same
time. The metal decomposes the water of the bath and becomes converted into
oxide setting hydrogen free.
The same theory applies to haloid salts such as chlorides. The chlorine and the
oxygen resulting from the decomposition of the water pass to the positive pole and
the base is reconstituted at the negative pole."
It has been proposed to utilise this principle in order to separate alkaline and
earthy alkaline bases such as potash and caustic soda for example from their saline
combinations but it is in all cases most essential to provide means for separating
the base from the acid as fast as the salt is decomposed in order to withdraw it
from the influences of the acid and of the current and obviate recombination of
the separated elements.
With this object attempts have been made to utilize the two methods hereinafter
described which have however yielded very inferior results in practice and bave
consequently been abandoned.
These two processes are-
I. Separation of the base with the aid of porous membranes or partitions.
With this object the vessel containing the solution to be electrolysed is divided
into two compartments by a porous partition and an electrode is immersed in the
liquid in each compartment. The base is collected in the compartment corre-
sponding to the negative electrode and the acid or oxygenised compound of chlorine
in the other compartment. This method can never be employed in practice on
account of two important disadvantages namely (1) the porous partitions present very

page_text: considerable resistance to the passage of the electric current so that a high electro
motive force is necessarily employed and much motive power is wasted. Moreover
the porous partitions become clogged and are soon rendered useless. (2) When
the base set at liberty at the negative pole is of a soluble nature such as soda and
potash a great portion of the current passes to this base and decomposes it into
metal and oxygen directly the quantity of base formed has attained a certain pro-
portion thus occasioning considerable waste of motive power and rendering it
impossible for the production to exceed certain limits. On account of these con-
siderations we have abandoned the employment of porous partitions.
11. Separation of the base by the employment of mercury.
The bottom of the electrolysing vessel is covered with a layer of mercury
electrically connected with the negative pole of the source of electricity. The
positive electrode is immersed in the saline solution which remains above the
mercury.
As fast as the salt is decomposed the metal passes to the negative pole constituted
by the mercury and amalgamates with the latter. The acid or oxygenised com-
pound of chlorine remains in the saline solution.
When carried out in this way this process has never yielded practical results.
In fact as fast as the proportion of metal in the amalgam increases the latter being
in contact with the saline solution is decomposed by it so that the formation of
amalgam stops in a very short time after which the energy of the current is
expended to no useful purpose.
Now by means of our present invention it is rendered possible to automatically
remove the amalgam of mercury as fast as it is formed from contact with the
saline solution and from the influence of the electric current and to continually
replace this amalgam by fresh or unamalgamated mercury. By these means all the
aforesaid disadvantages mentioned are removed and the mercury process is enabled
to acquire considerable commercial value.
And in order that the said invention may be fully understood we shall now
proceed more particularly to describe the same and for that purpose shall refer to
the several figures on the annexed sheet of drawings the same letters of reference
indicating corresponding parts in all the figures.
Figures 1 and 2 of the accompanying drawings are diagrams illustrating the
principle of our invention..
Figures 3 and 4 illustrate in longitudinal and transverse section respectively an
example of an apparatus employed in carrying out our invention in practice.
We think it desirable in the first place to set forth in detail the data on which
we have commenced our operations and the conclusions which we have deduced
therefrom in order to ascertain with precision the characteristics of our invention
and determine the scope of our claims.
In order to more clearly explain the principles whose application has enabled us
to obtain the desired results we have represented in Figure 1 of the annexed
drawing an imaginary apparatus the working of which would be impossible in
practice but which presents the advantage of facilitating the demonstration of
our theory.
In this drawing S represents a solution of any alkaline or earthy alkaline salt,
M is a layer of mercury represented as floating or being suspended upon the
surface of the saline solution and E represents the water or acid employed for
removing the metal from the amalgam in order to form the base or the salt which
is to be manufactured. The vessel is provided with two electrodes the positive
electrode (p) being immersed in the solution S and the negative electrode (n)
entering the lower part of the mercury.
If it were possible to construct an apparatus of this description in practice it
would give the desired results by reason of the following principle of action
which forms the basis of all the practical apparatus derived from this imaginary
arrangement.
1. Separation of the amalgam and of the mercury by means of the difference in

page_text: their densities the amalgam being lighter than the mercury and its relative lightness
increasing in proportion to the amount of metal it contains. Under these conditions
the action of the apparatus would be as follows-
The electric current would decompose the saline solution S in the usual way
and the metal passing to the negative pole would form an amalgam on the under
surface of the mercury at M. But this amalgam directly it is formed
being less dense than the mercury would ascend through the mercury M and
would accumulate on its upper surface at yy' where it would be decomposed by
contact with the water at E and the base or solution of the alkaline or
earthy alkaline base would be directly formed at a degree of concentration
varying as required in accordance with the duration of the passage of the electric
current.
This apparatus consequently complies with the conditions hereinbefore set forth.
The amalgam directly it is formed at a ascends to yy and is withdrawn from
contact with the saline solution acting at and also from the direct influence
of the current flowing between the two electrodes from p to n whilst the
mercury which is amalgamated at xx is perpetually renewed and replaced by
pure and active mercury from above. The great value of means capable of
realizing this theoretical arrangement in a practical manner will now be readily
understood.
On referring to the imaginary arrangement represented in Figure it will be
found that the arrangement of the parts situated above the line can be
readily obtained in practice. There is no difficulty in constructing a vessel con-
taining the layer of amalgamated mercury M situated underneath the layer of
water E. The amalgam floating on the top of the mercury transfers the metals to
the water in order to form the base and the pure mercury naturally descends to
the bottom at a¹. The mercury being heavier than any known saline solution
it is necessary to provide means for bringing the lower layer of pure mercury
into contact with the saline solution. With this object we employ the method next
hereinafter described which forms the complement of the principles hereinbefore
set forth.
i
II. By means of our invention we obtain a continuous flow of the lower layer
of pure mercury and a rapid passage of this mercury in a thin sheet into the
saline solution over an inclined surface forming the negative electrode facing the
positive electrode the amalgam formed. being removed from the action of the solution
and from the influence of the current immediately after its rapid passage over the
said surface.
A diagram illustrating an arrangement capable of obtaining this result is repre-
sented in Figure 2 of the accompanying drawings the mercury being contained in
a. separate vessel. The lower layer of pure mercury at a flows over an inclined
surface in a thin film or sheet at XX and passes rapidly through the saline
solution S. At X the amalgam formed is withdrawn from the action of the
solution and of the current and is elevated from. X to y by any suitable elevating
apparatus.
At M separation, in order of density takes place as herein before described. The
water absorbs the metal to form the base and the disamalgamated mercury falls to
the bottom whence it flows away and is amalgamated at XX' as stated with
reference to the arrangement in Figure 1 afterwards returning to the upper part
and thus keeping up a continuous circulation.
We have set forth at some length what may be termed the genesis of our method
with the aid of diagrams in order to shew clearly the essential principle of the'
invention as regards the construction of the apparatus and the method of operating
as hereinbefore set forth..
The accompanying drawings illustrate by way of example an apparatus con-
structed according to our: invention and enabling the same to be performed in
practice but we do not limit ourselves to this construction as it is evident that the
+

page_text: details of construction may be considerably modified without departing from the
principles of our invention.
In the said drawings Figure 3 represents the apparatus in longitudinal section
and Figure 4 represents the apparatus in transverse section on the line 1-2
Figure 3.
In the following description in order to obviate repetitions it is assumed that the
invention is applied to the manufacture of caustic soda by the electrolysis of
chloride of sodium but it must be clearly understood that the operation may be
performed upon any solution of a salt having an alkaline or earthy alkaline base
(such as potash, soda, ammonia, magnesia, alumina, and the like) either for the
purpose of separating the base from the salt or for preparing therewith any other
saline solution. In the first case the amalgam formed is decomposed with pure
water and in the second case by a suitable acid. For example in preparing a
carbonate a current of carbonic acid may be caused to pass through the water
employed for decomposing the amalgam.
The solution to be electrolysed, indicated at S is contained in a vessel C and the
water E employed for removing the sodium from the amalgam, in order to obtain the
caustic soda, is contained in a tank B. This water may be heated in order to
accelerate the reaction.
Inclined electrodes N P are immersed in the solution in the vessel C. The
negative electrode is constituted by one two or more plates N of iron, copper or
other suitable metal. The upper surface of this electrode is amalgamated by
known processes (by electrolytic action in the case of iron or by simple friction in
the case of copper). The object of this amalgamation is to enable the mercury to
spread over the electrode in a uniform layer. Without this precaution the mercury
would pass over the surface of the plate in the form of globules and would be in a
very unfavourable condition for taking up the metal in the solution. The plates
aforesaid are connected to the negative pole of the source of electricity by a
conducting bar D.
At their lower extremities these plates are bent upwards in such a manner as to
form gutters H for the reception of the amalgamated mercury.
The positive electrodes made of platinum or other suitable metal are placed
facing or opposite to the negative clectrodes N in such a manner that the mercury
flows downwards in the space between the two electrodes.
It is evident that electrodes of a conical and continuous or any other suitable
shape may be substituted in place of the flat or plane electrodes employed in the
example illustrated in the drawing.
The mercury is supplied to the upper part of the electrodes by means of a dis-
tributor constituted by a trough G communicating with one or more series of small
tubes g having their lower extremities contracted or taper and extending the whole
length of the negative electrodes.
We will now proceed to describe the arrangements employed for producing the
automatic circulation of the mercury.
For this purpose a combination of tubes or pipes marked T. U. V. (Figure 3) is
employed. The pipe T provided with a descending Ụ shaped bend or trap & con-
nects the tank B with the upper part of the mercury in the gutters H. The pipe U
having an upward bend at u u² connects the lower parts of the gutters H with a
collector F and the pipe V having an upward bend at v proceeds from the bottom
of the tank B at v' and likewise communicates with the collecting vessel F.
An elevating apparatus I (such as a chain of buckets or noria for example) takes
up the mercury from the collector F and discharges it into a shoot J from which it
flows into the distributor G.
The action of this apparatus is as follows. Let it be assumed that a suitable
quantity of mercury and other liquids has been introduced into the apparatus, that
the electric current is supplied to the electrodes and that motion is imparted to the
elevator. I.

page_text: The mercury flowing from the distributor G passes through the series of con-
tracted tubes g and descends in the form of a sheet or film over the surface of the
electrodes N. In its passage between the electrodes P and N the mercury
gradually becomes charged with sodium resulting from the electrolytic decom-
position of the saline solution S after which it passes into the gutters H H. During
the passage between the electrodes there is no danger of any appreciable decom-
position of the amalgam formed, the amalgam being decomposed with difficulty
owing to the small proportion of metal which it contains and when this proportion
has increased sufficiently to admit of the decomposition the amalgam passes into the
gutters H where it is secluded from the electric action exerted between the two
electrodes. In order to protect the said analgam from contact with the saline
solution sulphuret of carbon (or in general any liquid, lighter than the amalgain
and heavier than the saline solution) is introduced into the gutters H so as to cover
the amalgam as represented at s and separates the latter from the solution S.
Separation in order of density takes place in the gutters H in accordance with
the principles hereinbefore set forth. The purest mercury descends to the bottom
at m and the proportion of sodium in the amalgam increases towards the upper part
the whole being covered by the layers of sulphuret of carbon.
The pipe T communicating with the gutters H at a point t' where the amalgam
containing the greatest proportion of sodium is situated conducts this amalgam into
the tank B.
In order that the sulphuret of carbon at s floating upon the top of the amalgam
may not flow away through the tube T the latter is provided with the U shaped
bend at t which is always filled with a column of amalgam balancing the
pressure of the liquid (amalgam, sulphuret, and solution in the vessel C) situated
above the level a.
The relatively pure mercury collected in the bottom of the gutters at m escapes
at u and flows through the pipe U into the collector F.
The bend in the pipe U at is so arranged that the column of mercury un
balancing the pressure of the liquid (mercury, amalgam, sulphuret, and saline
solution) above the level u prevents the mercury from escaping through the orifices
at until the said mercury by reason of its purity has acquired the necessary
density.
On the other hand the amalgam flowing into the tank B distributes itself in order
of density at M on the bottom of this tank the mercury richest in sodium passing to
the upper part at y y where it is in contact with the water E which decomposes it
and takes up the sodium to form the caustic soda the exhausted amalgam sinking
gradually so that the mercury at is free from sodium.
This mercury is discharged at through the pipe V (provided with a bend at v
in order to preserve the level at y y' in the vessel B) and mixes with the mercury
supplied from the gutters H H to the general collector F.
From this collector the mercury is taken up by the elevator I and returned to the
distributor G the circulation being thus rendered continuous.
The apparatus hereinbefore described fulfils all the conditions hereinbefore set
forth and presents moreover the advantage of being automatic and continuous in its
action.
It is possible to obtain in the vessel E either caustic soda, potash or ammonia at
any degree of concentration, for this purpose it is simply necessary to prolong
sufficiently the duration of the operation. The soda solution may be drawn off
through a cock R arranged above the level y y' of the mercury in the vessel B or
in any other suitable manner.
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed we declare that what we
claim is
1. In the manufacture of alkaline and earthy alkaline bases or salts or com-
pounds thereof by the electrolysis of saline solutions a method or
Process Consisting

page_text: essentially in forming by electrolysis an amalgam of the metal of the base, removing
this amalgam from the action of the current and separating it from the other part
of the mercury by the difference in the densities, the amalgam richest in metal
being allowed to rise to the surface where it is brought into contact with the water
or the acid employed for decomposing it in order to form the required product,
whilst the lower layer consisting of mercury is again subjected to electrolysis in the
presence of the saline solution in order to continuously form a fresh supply of
amalgam which directly it is formed is removed in like manner from the action of
the electric current and of the saline solution being again separated from the
mercury by the difference in the density substantially as hereinbefore described.
2. In the method or process of manufacture hereinbefore described and claimed
the means consisting in running off in a continuous manner the lower layer of
mercury separated from the amalgam by the difference of densities, passing this
mercury in a thin sheet or film through the saline solution over one or more
inclined surfaces forming the negative electrode facing the positive electrode, the
amalgam thus formed being removed from the action of the current and of the
saline solution immediately after passing over the said inclined surface or surfaces
and being again separated from the mercury by the difference in the densities and
thus obtaining a continuous circulation substantially as herein before described.
3. In combination with the process of manufacture herein before described and
claimed an apparatus consisting essentially of a tank or vessel in which the amalgam
is brought into contact with the water employed for exhausting it, a vessel con-
taining the saline solution (in which is or are immersed the positive electrode or
electrodes with the inclined negative electrode or electrodes bent upwards at their
base in the form of gutters) a collector for the reception of the disamalgamated
mercury, an elevating device, a distributing device, causing the mercury to be
spread in a thin sheet or film over the negative electrodes and a system of pipes
connected with the terminal gutters at the lower end of the negative electrodes with
the tank for exhausting the amalgam and with the mercury collector substantially
in the manner and for the purpose herein before set forth.
4. In apparatus employed in combination with the improved method or process
of manufacture referred to in the first and second claiming clauses the arrangement
of the negative electrodes constituted by one or more inclined metallic amalgamated
plates the said electrodes being provided at their lower ends with gutters in which
the mercury and the amalgam are allowed to arrange themselves in order of density
the surface of the amalgam being covered with a layer of sulphuret of carbon or
other liquid lighter than the amalgam and heavier than the saline solution all
substantially in the manner and for the purpose hereinbefore set forth.
5. In apparatus operating according to the method or process of manufacture
referred to in the first and second claiming clauses the combination of negative
electrodes amalgamated and terminating at their base in. gutters with a distributor
arranged at the upper part of the said clectrodes and constituted by a trough and
one or more series of tubes contracted at their lower extremities substantially in the
manner and for the purpose hereinbefore set forth.
6. In apparatus operating according to the method or process of manufacture
referred to in the first and second claiming clauses the combination of negative
electrodes provided with gutters at their lower extremities with a tank for the
exhaustion of the amalgam connected with the said gutters by a pipe T supplying
the amalgam rich in metal from the gutters to the said exhausting tank and with a
mercury collector connected with the said gutters by a pipe U taking the mercury
from the lower parts of the gutters and discharging it into the collector the said
exhausting tank being further connected with the said collector by the pipe V
conveying the disamalgamated or relatively pure mercury from the bottom of the
said tank and discharging it into the collector the said pipes T U and V being
provided with suitable bends for maintaining constant the levels of the mercury, of
the amalgam, and of the sulphuret of carbon in the gutters H as well as the level of
the amalgamated mercury in the exhausting tank B all arranged and operating

page_text: substantially in the manner and for the purpose herein before set forth with reference
to the accompanying drawings.
7. The general arrangement and combination of parts constituting an improved
apparatus for the manufacture of alkaline or carthy alkaline bases and of
their salts or compounds by the electrolysis of saline solutions in the presence
of mercury substantially as herein before described with reference to the accom-
panying drawings.
Dated this 14th day of September 1892.
J. H. JOHNSON & Co.,
47, Lincoln's Inn Fields, London, W.C., Agents: