Improvements in Oxidising Lead and Lead Compounds for the Construction of Electrical Accumulators.
Year: 1895

page_text: Date of Application, 26th Sept., 1895-Accepted, 8th Feb., 1896
COMPLETE SPECIFICATION.
Improvements in Oxidising Lead and Lead Compounds for the
Construction of Electrical Accumulators.
I, HENRY LEITNER, of Niederschönhausen in the Empire of Germany,
Philologist 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 :-
The process for oxidising lead and lead compounds which forms the subject of
the present application for Letters Patent is especially suitable for use in the
making of accumulators, because by means of the same it is possible to oxidise a
lead compound throughout in a very short space of time.
Carbon is not appreciably attacked as long as lead or lead oxide in sufficient
quantity is present or in intimate contact on the other hand a certain percentage of
carbon hastens the oxidation of the lead and the oxide through the increased
conductivity imparted to the mass thereby.
As soon as the peroxide is formed, the carbon particles are attacked and removed
by the nascent oxygen. By this removal the surface alone of the plate is at first
made porous.
But on continued use fluid penetrates into the hollows thus formed, and
gradually makes even the deeper layers porous until eventually the whole plate
forms a porous but coherent mass of peroxide. The composition of the paste
from which the plates are formed is as follows:-
Carbon (about 10%) and oxide of lead both in powder are intimately mixed
and a sufficiency of glycerine added so as to form with the lead oxide the already
technically known putty (glycerine-lead oxide putty).
The process consists essentially in treating chemically the lead to be oxidised
with an alkaline hypochlorite, preferably sodium hypochlorite and is effected in
the simplest manner by immersing the lead in an approximately saturated solution
of the salt. The lead is hereby oxidised on its outer surface, and as soon as the
thus partly prepared lead is treated with a relatively weak current of electricity
for a comparatively short time, an altogether oxidised mass is produced which can
be utilised for accumulator purposes to great advantage.
The manufacture can advantageously be carried out as follows, whereby an
accumulator is produced distinguished by its exceptional capacity and firmness as
well as by its power of resistance to outside influences. A pasty mass of oxide of
lead is taken and mixed with a small percentage of retort carbon dust and to the
mixture glycerine or other binding material is added. A quantity of lead tubes
formed of rolled up lead foil are then inserted in the mass, and the whole is then
pressed into a hollow carbon body preferably cylindrical formed by compressing
carbon powder with a suitable binding material. After this the whole is immersed
in a solution of sodium hypochlorite preferably saturated, which converts the lead
oxide on the surface into peroxide. The passing of an electric current through
the mass causes the lead oxide and lead to be thoroughly peroxidised, and the
binding material to be removed. The metallic lead has its strength undiminished
being entirely encased in the firm lead oxide mass. An electrode constructed in
this manner distinguishes itself by uncommon strength and efficiency and experi-
ments have demonstrated that the use of these electrodes in accumulators gives
much more storage capacity than is attained with the usual kind.

page_text: 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. The above described process for oxidising lead and lead compounds for
accumulators characterised by the treating of the same with an alkaline hypo-
chlorite, for the purpose of effecting a thorough oxidation throughout the entire
mass.
2. The method of carrying into effect the process claimed above whereby metallic
lead is embedded in a pasty mass of lead oxide capable of conducting electricity
and sodium hypochlorite is applied to oxidise the lead and lead oxide in such a
manner that the whole mass becomes thoroughly oxidised without suffering any
diminution of its strength.
Dated this 25th day of September 1895.
W. P. THOMPSON & Co.,
31, High Holborn, London, W.C., Patent Agents for the Applicant.