Improvements in the Electrolysis of Metallic Salts.
Year: 1895

page_text: Date of Application, 11th Apr:, 1895
Complete Specification Left,. 28th June, 1895-Accepted,, 3rd Aug., 1895
PROVISIONAL. SPECIFICATION.
Improvements in the Electrolysis of Metallic Salts.
I. CARL KELLNER of No: 29 Wasagasse, Vienna. IX, Austria, Doctor of
Philosophy and Director of The Kellner-Partington Paper Pulp Co: Limited'do
hereby declare the nature of this invention to be as follows:-
In all processes heretofore known to me of electrolytically splitting, up
alkaline-chlorides in which a.mercury cathode is used, and generally of compounds
whose electro-positive constituent forms an amalgam with mercury, the greatest
difficulty is experienced in separating many metals from the mercury, with which
they are united, in the same time as that in which the said' metals are precipitated
by the electrical current upon the mercury. Also in all apparatus heretofore
known, so far as I am aware, it is difficult. for the energy produced by the
decomposition of the amalgam.to. be recovered in the form of electricity at a
higher potential than that used for effecting the electrolytic decomposition,
because it is impracticable to connect the forming cells in series with one another
on account of the difference of. potential' with relation to the main.current.
Various means have been proposed' for obviating the first-mentioned difficulty,
namely
--
1, increase of surface;
2, heating the re-action liquid,.
3, separating the amalgam and the mercury in consequence of their different
specific gravities;
4, using the amalgam to form a galvanic element; and
5, connecting up the mercury as a double-pole electrode.
These means do in most cases certainly effect the object in view, but entail
at the same time many disadvantages which in the cases. enumerated under 1, 2
and 3, consist in the use of a considerable quantity of mercury; in the case
mentioned under 4, in the difficulty, of maintaining the cells formed, at separate
potentials; and in the case mentioned under 5 in the scarcely possible prevention
of oxidation of the mercury after a long, period of working.
For this reason it has been proposed to employ a second smaller source of
current (a dynamo machine) by means of which the mercury would be continuously.
enriched with a certain quantity of metal. But this device gives very uncertain
results, because, in consequence of the occlusion of hydrogen; the metal is.not
given up by the mercury, even though there be intimate contact with water, and
because, furthermore the connecting together in series of apparatus which are
traversed by two mutually complementary currents, offers considerable difficulties
in working on a large scale, in consequence of differences in potential.
The present invention relates to a methodi designed to obviate the above
mentioned difficulties and drawbacks.
This method consists essentially in removing the mercury, together with the
amalgam produced in the well known manner, from the decomposing cell, and in
conveying the same from the latter into cells that are entirely separated and
bodily and electrically from the decomposing cell, that are each provided with
a separate electrode, and are capable, by connection together in series, of being
brought to a potential independently of the decomposing current.

page_text: In the accompanying drawings,
Fig. 1 illustrates diagrammatically apparatus suitable for carrying the above
mentioned method into practice.
...
The decomposing cells a in which the metallic salt is decomposed by the current,
are entirely separate both bodily and electrically from the forming cells bb'
that is to say, from those spaces in which the mercury employed as the kathode
is to give up the metal, for instance sodium or potassium, combined therewith.
In order to prevent electrical connection between each decomposing cell and
the corresponding forming cell, the mercury conveyed from the one to the other
must not be continuous or coherent. This may be effected for example by causing
the mercury flowing out of the decomposing cell a through the pipe c, and which
constituted the kathode k in that cell, to flow into a divided rocking trough d, so
that by emptying alternately one and the other compartment of the trough, the
mercury is caused to flow into the supply pipe e of the forming cell b. This
forming cell is similarly connected with the second cell 1, and if desired this
latter can be similarly connected with a third cell and so on. The mercury from
the last forming cell is returned into the respective decomposing cell a by means
of pipes and g, and au interposed pump p and a rocking trough d'.
All the decomposing cells a by their kathodes k and anodes n may be connected
together in parallel or in series. But the forming cells 661 corresponding to the
several decomposing cells are on the contrary connected together in series, each of
them being provided with a separate electrode h arranged opposite to the amalgam
supplied to them by the pipes e, and the arrangement being such that the amalgam
of the first cell is connected with the electrode h of the second cell b¹, and the
amalgam of this cell is connected with the electrode h of the next cell, and so on.
From a source of current 1, (Fig. 2) working specially for this purpose, with a
low potential, and independent of the main dynamo i, there is now sent through all
the series connected forming cells bb, a current which accelerates the decom-
position of the water by the electro-positive metal in the amalgam and in
consequence thereof liberates the mercury from the metal. But the forming cells
may also, in consequence of the current generated in the said cells by the mutual
re-action of the liquid in the cells bb' and the amalgam, be employed as a source
of current for the performance of external work. In this case the dynamo would
of course be omitted, and if required, other decomposing cells can be included in
circuit with such cells as for example by placing the decomposing cells shown in
Fig. 3 hetween the + and ends of the conductor connected with the extreme
cells shown in Fig. 1.
-
It is obvious that in place of the rocking or tipping troughs, other means, such
as for instance cocks or valves, may be employed for interrupting the electrical
connection between each decomposing cell and the corresponding forming cell.
By the use of resistances, the potential of any cell, or of all the cells, may be
readily regulated, and in this manner adjustment can always be readily made for
the variations which occur when electrolytic decomposition is being effected by
means of a mercury cathode.
The method hereinbefore described is capable of being carried out with most of
the apparatus heretofore proposed for use, wherein mercury is employed as the
cathode.
Deted this 11th dow of Anvil 100-

page_text: Improvements in the Electrolysis of Metallic Salts.
1, CARL KELLNER, of No. 29 Wasagasse, Vienna, IX, Austria, Doctor of
Philosophy and Director of The Kellner-Partington Paper Pulp Co. 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 :-
In all processes heretofore known to me in which a mercury kathode is used for
the electrolytical decomposition of alkaline chlorides and, generally, of compounds
whose electro-positive constituent forms an amalgam with mercury, the greatest
difficulty experienced in separating many metals from the mercury with which
they are united, in the same time as that in which the said metals are precipitated
upon the mercury by the electrical current. Also, in all apparatus heretofore
known, so far as I am aware, it is difficult for the energy produced during the
decomposition of the amalgam to be recovered in the form of electricity at a
higher potential than that used for effecting the electrolytic decomposition,
because it is impracticable to connect the forming cells in series with one another
on account of the difference of potential with relation to the main current.
Various means have been proposed for obviating the first-mentioned difficulty,
namely:-
(1.) Increase of surface;
(2.) Heating the re-action liquid ;
(3.) Separating the amalgain and the mercury by means of their different
specific gravities;
(4.) Using the amalgam to form a galvanic element; and
(5.) Connecting up the mercury as a double-pole electrode.
These means do in most cases certainly effect the object in view, but entail at
the same time many disadvantages, which, in the cases enumerated under (1.), (2.),
and (3.), consist in the use of a considerable quantity of mercury; in the case
mentioned under (4.), in the difficulty of maintaining the cells formed, at separate
potentials; and in the case mentioned under (5.), in the scarcely possible prevention
of oxidation of the mercury after a long period of working.
For this reason it has been proposed to employ a second, smaller source of
current (a dynamo machine) by means of which the mercury would be continuously
enriched with a certain quantity of metal. But this device gives very uncertain
results, because, in consequence of the occlusion of hydrogen, the metal is not
given up by the mercury, even though there be intimate contact with water, and
because the connecting together in series of apparatus which are traversed by two
mutually complementary currents, offers considerable difficulties in working on a
large scale, in consequence of differences in potential between the two currents.
The present invention relates to a method designed to obviate the above
mentioned difficulties and drawbacks.
This method consists essentially in removing the mercury, together with the
amalgam produced in the well known manner, from the decomposing cell, and
conveying the same into cells that are entirely separated, bodily and electrically,
from the decomposing cell, are each provided with a separate electrode, and are
capable, by connection together in series, of being brought to a potential
independent of the decomposing current.
Fig. 1 of the drawings filed with my Provisional Specification illustrates
diagrammatically, apparatus suitable for carrying the above mentioned method into
practice.
The cells a, in which the metallic salt is decomposed by the current, are entirely

page_text: separate, both bodily and electrically, from the forming cells b, b1,-that is to say,
from those spaces in which the mercury employed as the kathode is to give up the
metal, for instance sodium or potassium, combined therewith.
In order to prevent electrical connection between each decomposing cell a and
the corresponding forming cells b, 61, the mercury conveyed from the one to the
other must not be continuous or coherent. This may be effected, for example, by
causing the mercury which flows out of the decomposing cell a through the pipe c
and which has constituted the kathode k in that cell, to flow into a divided rocking
trough d, so that by emptying alternately one and the other compartment of the
trough the mercury will be caused to flow into the supply-pipe e of the forming
cell b. This forming cell is similarly connected with a second cell b¹, and if
desired this latter can be similarly connected with a third cell, and so on.
mercury contained in the last forming cell is returned into the respective
decomposing cell a by means of pipes fand g, an interposed pump p, and a rocking
trough d¹.
The
All the decomposing cells a may be connected together by their kathodes k and
anodes n either in parallel or in series. But the forming cells b, b' corresponding
to the several decomposing cells are on the contrary connected together in series,
each of them being provided with a separate electrode h arranged opposite to the
amalgam supplied to it by the pipe e, and the arrangement being such that the
amalgam of the first cell is connected with the electrode h of the second cell b¹,
and the amalgam of this cell is connected with the electrode h of the next cell,
and so on.
From a source of-current (Fig. 2), working specially for this purpose with a
low potential, and independent of the main dynamo i (Fig. 1), there is or may in
some cases be now sent through all the series-connected forming-cells b, b', an
electric current which accelerates the decomposition of the water (which forms the
electrolyte of the forming cells b, b') by the electro-positive metal in the amalgam,
and in consequence thereof liberates the mercury from the metal. This use of a
separate electric current is specially advantageous for starting or facilitating the
decomposition of amalgams that are difficult to decompose.
But the forming cells may also, in consequence of the current generated in them
by the mutual reaction of the therein contained liquid and amalgam, be employed
as a source of current for the performance of external work. In this case the
dynamo would of course be omitted, and, if required, other decomposing cells
could be included in circuit with such cells-as, for example, by placing the
decomposing cells shown in Fig. 3 between the + and ends of the conductor
connected with the extreme cells b, b', shown in Fig. 1.
It is obvious that in place of the rocking or tipping troughs, other means, such
as for instance cocks or valves, may be employed for interrupting the electrical
connection between each 'decomposing.cell and the corresponding forming cells.
By the use of resistances, the, potential of any cell, or of all the cells, may be
readily regulated, and in this manner adjustment can always be readily made for
the variations which occur when electrolytic decomposition is being effected by
means of a mercury kathode.
The method herein before described is capable of being carried out with most of
the electrolytic apparatus heretofore proposed for use; wherein mercury is employed
as the kathode.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed 1 declare that what I
claim is :-
1. In the electrolysis, by means of a mercury kathode, of compounds the electro-
positive constituent of which forms an amalgam with mercury, removing the mercury
employed as the kathode, after it has become enriched with an electro-positive
metal, from the decomposing cell and transferring it into forming-cells b', which
are bodily and electrically separate from the said decomposing cell, are provided

page_text: with electrodes h, and are adapted to be brought, by being connected together in
series, to a potential independent of the decomposing current, substantially as
hereinbefore described for the purpose specified.
2. In the method specified in the preceding claim, starting the decomposition of
the water in the forming-cells b, b1 by passing a separate electric current through
the latter, so as to thereby ensure the decomposition of amalgams that are difficult
to decompose, substantially as hereinbefore described.
3. In the method specified in Claim 1, employing the current generated in the
forming-cells for the purpose of performing external work, substantially as
hereinbefore described.
4. My improved electrolytical apparatus combined and operating substantially
as herein before described with reference to and represented diagrammatically in
the drawings filed with my Provisional Specification.
Dated this 27th day of June 1895.
F. WISE HOWORTH,
46, Lincoln's Inn Fields, London, W.C., Agent for the Applicant.