Method of and Apparatus for Electrolytical Decomposition while using Quicksilver as Cathode.
Year: 1893

page_text: Date of Application, 3rd Aug., 1893-Accepted, 9th Sept., 1893
A. Method of and Apparatus for Electrolytical Decomposition while
using Quicksilver as Cathode.
I, PETER JENSEN of 77 Chancery Lane, London, Chartered Patent Agent do
hereby declare the nature of this invention (a communication to me from abroad by
Alf Sinding-Larsen of Christiana, Norway, Electrical Engineer) and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :—
The apparatus for electrolytical decomposition using quicksilver as cathode have
had the defect that the water is decomposed directly on the surface of the cathode,
because alkaline metallic amalgamate formed while exposed to the action of the
water, where the current is too weak, will give off its alkali-metal to the water and
form hydroxide and hydrogen. If as is the case in some of the most recently
proposed apparatus of this kind, the quicksilver surface acted on by the current is
allowed to touch directly a porous partition applied as diaphragm between the
cathode and anode space, this defect is still further increased because the liquid
which must appear between the wall of the cell and the quicksilver obtains a
larger surface for attacking the separated alkali-metal than the surface of quick-
silver offered to the current, .: only those parts of the quicksilver which touch
immediately the pores of the diaphragm. The hydrogen gas evolved by the
decomposition of the water will then, because of the space it occupies, considerably
reduce the quicksilver surface that can be acted upon by the current and also draw
much of the electrolyte with it up into the space wherein the alkali-metal should
be dissolved.
This present invention aims at removing these defects two independent means
being employed which act so as to prevent the aforesaid phenomena which are
hurtful to the economical progress of the process.
One means consists in the application of the anode and cathode in the same space,
the decomposing cell, wherein the quicksilver forming the cathode is contained
with a surface perfectly free towards the electrolyte, the quicksilver having also a
sui face perfectly free towards another space which is quite independent of the
decomposing cell and contains the reagent necessary for the production of the
alkalı compound in question.
The other means consists in putting the mass of quicksilver in circulation between
the two active surfaces viz.: the one towards the decomposing liquid and the one
towards the dissolving reagent, so that the water of the electrolyte gets no time to
react on the alkali-metal.
The
The electrolytical resistance can in an apparatus of this kind be reduced to a
minimum or nearly to the theoretical, because there is nothing to prevent the anode
from being applied in the immediate vicinity of the quicksilver surface.
contrary electromotive force arising by the polarisation of the anode may be easily
reduced by giving the anode, for instance in the form of a round rod, a powerful
rotation around itself so that it always turns a gas-free surface towards the
cathode.
The circulation in the mass of quicksilver may be produced either by specially
constructed devices such as pump or propeller or by heat, or it may be effected by
the variation in specific gravity which the quicksilver undergoes by taking up
alkali-metal. In the latter case the circulation must be in a vertical plane, while
in the former it may be in a horizontal plane.
In the accompanying drawing is illustrated an apparatus which may be advan-
tageously used for carrying the invention into effect."
Fig. 1 is a vertical longitudinal, Fig. 2 a horizontal section and Fig. 3 a vertical
section on line 32 Tia 2

page_text: A is a vessel of insulating material with annular outer compartment B. The
part A contains the electrolyte, while the part B is for circulation of the quicksilver
cathode C and for containing the solvent liquid D. At one point of its circum-
ference the annular space B has two vertical cross walls E connected at top by a
slanting wall F, see Figs. 1 and 3, and terminating below so far as to dip into the
mercury; the space so formed is open towards the electrolyte space and forms a
niche wherein the anode G is inserted. Just under the anode and in the bottom of
the annular space a metal piece H is placed, over which the quicksilver passes in a
thin layer and communicating with the negative conducting wire. The quicksilver
is put into rotation by a paddle-wheel I. The anode G is on a rotating spindle K.
The space A having been charged with a suitable amount of salt and water, and
the space B with quicksilver and water, the paddle-wheel I and anode G are
rotated. The quicksilver passing under the anode will then by the action of the
electric current take up the salt of the metal while chlorine is set free at the anode;
this will to some extent place itself at the underside of the anode but will because
of the rotation of the latter be carried away from it and rise up through the
electrolyte in such manner that no deleterious polarisation takes place.
The amalgam formed passes under the wall E and now comes in contact with
the solvent liquid (for instance water) which takes up the alkali-metal and forms
a lye.
In order that the electrolyte may not be carried away under the edge of the
wall E the latter is covered with a metallic amalgam to which the quicksilver
adheres and hinders the passage of the liquid.
The hydrogen evolved in the space B may be collected and be used as fuel for
boiling down the lye.
The apparatus may of course be used for a variety of electrolytical purposes.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In connection with the electrolytical decomposing apparatus the process for
preventing the decomposition of the formed amalgam by contact with the water of
the electrolyte consisting in keeping the quicksilver in circulation between the
point where it takes up metal and the point where it again gives it up to the
reagent serving to produce the desired combination.
2. In electrolytical decomposing apparatus the application and use of a quicksilver
cathode having a free surface towards the electrolyte as well as towards the reagent
for production of the alkaline compound in question.
3. In electrolytical decomposing apparatus of the kind as firstly and secondly
claimed, the arrangement, that those walls pipes or spaces which form separating
or connecting links between the decomposing space and the solution space and are
in contact with the quicksilver are provided with a covering of amalgam for the
purpose of causing the adhesion of the quicksilver to the walls and thus hindering
the passage of the liquid from one space to the other, between the quicksilver and
the walls.
4. In clectrolytical decomposing apparatus of the kind described in the first or
second claim the arrangement that the anode or anodes during the process are kept
in rotation for the purpose of removing the gas globules formed upon the anode
from its active side.
5. The construction of electrolytical decomposing apparatus shewn on the
drawing.
JENSEN & SON,
77, Chancery Lane, London, W.C., Patent Agents.