Improvements in Electrolysis.
Year: 1898

page_text: PROVISIONAL SPECIFICATION,
Improvements in Electrolysis.
A communication from abroad from Messrs. SOLVAY & Co., of 25, Rue du Prince
Albert, Brussels, Belgium, Manufacturers.
I, WILLIAM LLOYD WISE, of 46, Lincoln's Inn Fields, W.C., in the County of
London, Consulting Engineer and Chartered Patent Agent, do hereby declare the
nature of this invention to be as follows:
Amongst the causes which prevent the theoretical yield being obtained in
electrolytic processes, the most important is the partial recombination of the
products separated by the current. For example, in the case of the decomposition
of an alkaline chloride (chloride of sodium, or chloride of potassium) with a
mercury cathode, chlorine liberated at the anode dissolves in the electrolyte and
The
re-combines with sodium or potassium being liberated at the cathode."
solubility of chlorine in solutions of alkaline chlorides is, in fact, very appreciable,
and it is only when these solutions are saturated with chlorine that this gas begins
to be evolved. This saturation is therefore constantly maintained notwithstanding
the continual re-combinations above referred to. The diminution of yield due to
this permanent presence of dissolved chlorine can be obviated to a large extent
by separating the liquid in which the anode is placed from the liquid in which the
cathode is placed, by means of a diaphragm, but it is a well known fact that
diaphragms offer resistance to the passage of the current, and moreover constitute
a very great practical complication.
Now this invention has for object to prevent or retard in a simple manner and
without the use of an ordinary diaphragm, recombination of the products, or part
thereof, of electrolytic processes and thereby to increase the yield or efficiency of
such processes.
For this purpose the electrolyte, instead of being homogeneous throughout its
mass, is separated into two distinct layers. The lower layer, which is in contact
with the mercury, is saturated or almost saturated with salt, and has consequently a
maximum degree of density. The upper layer, which is situated directly over the
lower layer, is not so rich in salt, and is consequently less dense. In this last
layer the anode or anodes is or are placed.
In the mercury process for the electrolysis of alkaline chlorides, the two layers
of different densities can be easily kept separate, because the process does not result
The dense lower layer serves
in any evolution of gas at the surface of the mercury.
the purpose of a diaphragm without the inconveniences attending the use of an
ordinary solid diaphragm. As it always remains in contact with the mercury,
and as it does not mix with the liquid saturated with chlorine that surrounds the
anode or anodes, is remains practically free from chlorine, and thus the re-formation
at the cathode of the chloride to be decomposed is prevented and a maximum yield
or efficiency of the electric current obtained.
It will be understood that the line of separation between the two layers will be
situated between the anode or anodes and the cathode, for example, halfway

page_text: between the two. It is obvious that the layers, by reason of the electrolytic action,
will both tend to become poorer in salt. They must therefore be kept at their
proper relative strengths. The best means of effecting this, is to cause the liquids
constituting the two layers to flow off separately and in a continuous manner from
one end of the electrolytic apparatus, to dissolve further quantities of salt in the
said liquids, and subsequently to return them to the other end of the electrolytic
apparatus and cause them to again assume the conditions of layers arranged one
above the other. Other means may however be adopted for supplying additional
salt to the two liquids to form the two layers without departing from the principle
of the invention.
The supply of salt to the two liquids should be regulated in such a manner as to
maintain between them a suitable difference of density.
Dated this 841 of Manal 1000
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.
A communication from abroad from Messrs. SOLVAY & Co., of 25, Rue du Prince
Albert, Brussels, Belgium, Manufacturers.
I, WILLIAM LLOYD WISE, of 46, Lincoln's Inn Fields, W.C., in the County of
London, Consulting Engineer and Chartered Patent Agent, 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:-
Amongst the causes that prevent the theoretical yield from being obtained in
electrolytic processes, the most important is the partial recombination of the
products after they have been separated by the current, and in the case of the
decomposition of an alkaline chloride-chloride of sodium, or chloride of potassium,
for example with a mercury cathode, chlorine liberated at the anode dissolves in the
electrolyte and recombines with sodium or potassium that is being liberated at the
cathode. The solubility of chlorine in solutions of alkaline chlorides is, in fact,
very considerable, and it is only when these solutions are saturated with chlorine that
this gas begins to be evolved. This saturation is therefore constantly maintained
notwithstanding the continual recombination above referred to. The diminution of
yield due to this permanent presence of dissolved chlorine can be obviated to a large
extent by separating the liquid in which the anode is placed from the liquid in
which the cathode is placed, by means of a diaphragm, but is a well known fact
that diaphragms offer resistance to the passage of the current, and moreover
constitute a very great practical complication.
Now, this invention has for object to prevent or retard in a simple manner and
without the use of an ordinary diaphragin, the recombination of products obtained
by the electrolysis of alkaline chlorides with mercury cathodes and thereby to
increase the yield or efficiency of the process.
For this purpose the electrolyte, instead of being homogeneous throughout its
mass, is separated into two distinct layers. The lower layer, which is in contact
with the mercury, is saturated or almost saturated with salt, and has consequently
a maximum or almost a maximum degree of density. The upper layer, which lies
on the lower layer, is not so rich in salt, and is consequently less dense. In the
latter layer the anode or anodes is or are placed.
In the mercury process for the electrolysis of alkaline chlorides, the two layers of
different densities can be easily kept separate, because the process does not

page_text: esult in any evolution of gas at the surface of the mercury. The dense lower
ayer serves the purpose of a diaphragm without the disadvantages attending the
ase of an ordinary solid diaphragm. As it always remains in contact with the
mercury and does not mix with the liquid saturated with chlorine that surrounds
the anode or anodes, it remains practically free from chlorine, and thus the reforma-
tion, at the cathode, of the chloride to be decomposed is prevented and a maximum
yield is obtained from the electric current.
It will be understood that the plane of separation between the two layers must be
situated between the anode or anodes and the cathode-for example, halfway
between the two. It is obvious that the layers, by reason of the electrolytic action,
will both tend to become poorer in salt. They must therefore be kept at their proper
relative strengths. The best way of effecting this is to cause the liquids constitut-
ing the two layers to flow off separately and in a continuous manner from one end
of the electrolytic apparatus, to dissolve further quantities of salt in the said
liquids, and subsequently to return them to the other end of the electrolytic
apparatus so as to cause them to assume again the conditions of layers arranged
one above the other as before. Other ways may, however, be employed for supply-
ing additional salt to the two liquids forming the two layers, without departing
from the principle of the invention. The supply of salt to the two liquids should
be regulated in such a manner as to maintain between them a suitable difference
of density.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I declare that what
I claim is:
For the purpose of obtaining the maximum output in the electrolysis of au
alkaline chloride by means of a mercury cathode, the use of an electrolyte composed
of two layers, one of which is of great density, lies on the mercury, and is practically
free from chlorine, whilst the other layer of low density, lies on the former layer,
contains the anode or anodes, and becomes saturated with chlorine.
W. LLOYD WISE,
46, Lincoln's Inn Fields, London, W.C.,
Chartered Patent Agent.