Year: 1897

page_text: I, SYDNEY PITT, of Sutton in the County of Surrey, Gentleman, do hereby declare
the nature of this invention (which has been communicated to me from abroad by
Léger Bomel and Société Bisson, Bergès & Cie, 8 rue Rocroy, Paris,) and in what
manner the same is to be performed to be particularly described and ascertained in
and by the following statement :-
Zine accumulators have many advantages over lead: they have a greater electro
motive force, a larger capacity, greater lightness and above all there is no danger of
sulphation or oxidation.
Up to the present time they have not been commercially used because in charging
local actions are produced which lessen the output and with an open circuit they
discharge themselves little by little, the zinc being attacked by the acid solution.
In order to remedy these evils it has been proposed to employ amalgams but these
processes have not produced good results.
According to this invention a negative electrode is constructed which allows :-
1. The automatic amalgamation of zinc in proportion to its deposition upon a
conducting support.
2. The recuperation and preservation of the mercury set free during the discharge.
This process is based upon the two facts that:
a) mercury has the property of creeping along a deposit of electrolytic zinc
deposited upon a conducting plate to a height up to and even exceeding 8-10
centimetres.
b) zinc electrolised several times in sulphuric solution deposits itself upon a
conducting surface in such a pure state that the presence of a suitable quantity of
mercury renders it almost unattackable by the acid.
We set up a negative electrode formed of a plate or sheet of copper the bottom of
which plunges into mercury contained in a trough or suitably shaped vessel.
This arrangement allows during the charging of a continuous and progressive
amalgamation of the zine whilst the deposit is formed and during the discharge of the
recuperation and preservation of the mercury which may thus be used indefinitely.
In the annexed drawing Figure 1 shows in section an example of one of the
negative electrodes before the accumulator is charged and Figure 2 a section of the
said electrode after charging.
A is a copper sheet, it rests upon the bottom of a trough or elongated basin B
which before the accumulator is charged contains the mercury C as seen in Figure 1.
c is the zinc amalgam which whilst charging is deposited in the form of a spongy
layer upon the two faces of the copper sheet A as is shown in Figure 2.
Of course the supporting strips A instead of being of copper may be of zinc, lead,
platinum or other conducting material or material rendered such.
The troughs or basins B are of ebonite, porcelain, celluloid or of other non-
conducting material or material rendered such.
The supporting strips may be corrugated or flat, pierced with holes or not, or of
metallic wire or gauze. They may be of any suitable height and if needful a negative
electrode may be formed of any height by superposing the strips and their basins,

page_text: These latter may be connected together between themselves in any suitable
manner.
The electrodes- may be of any shape and if needful may be provided with guards
of insulating material in order that active material may not overhang.
The basins may be provided with suitable arrangements for preventing the escape
of mercury whilst permitting the supply to enter.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same is to be performed, I declare that
without limiting myself to the details of execution which may be varied as required,
what I claim is :-
A negative electrode for accumulators: constituted by the combination of a
supporting conducting strip and a trough or basin containing mercury in which the
said strip rests. This arrangement allowing, whilst charging; of continuous
amalgamation by the mercury which creeps along the strip of the electrolysed zinc
which is deposited upon. it and whilst discharging, of the recuperation and
preservation of the mercury which may thus be used again and again indefinitely.
Dated this 21st day of June 1897.