Improvements in the Manufacture of Elements or Electrodes for Voltaic Batteries and Electrolytic Decomposition Cells.
Year: 1893

page_text: Date of Application, 17th May, 1893
Complete Specification Left, 15th Nov., 1893-Accepted, 12th May, 1894
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Elements or Electrodes for
Voltaic Batteries and Electrolytic Decomposition Cells.
I, DESMOND GERALD FITZ-GERALD of 94, Loughborough Road, London,
S.W. Electrician, do hereby declare the nature of this invention to be as
follows:-
€
My invention relates to an improved method of producing elements or electrodes
for voltaic batteries and electrolytic decomposition cells, from an oxide of lead or a
mixture of different oxides of lead, by causing the moistened lead oxide or oxides to
set"
so as to be no longer liable to become disintegrated when immersed in an
aqueous liquid as is necessary in the subsequent operation of converting the set
material into dense, hard, and coherent peroxide of lead or spongy lead as the case
may be. It has heretofore been proposed to bring about this setting of moist lead
oxide by the action of a salt such as sulphate of aminonia or sulphate of lead.
My present invention consists essentially in the addition to the monoxide of lead
(litharge) or massicot minium or peroxide of lead or a mixture of two or more of
these oxides, of caustic fixed alkali (or a mixture of the two fixed alkalies) in the
presence of water, preferably, but not necessarily, by adding the alkali in solution
to the previously moistened and slightly consolidated inass of lead oxide, the mixing
of the lead oxide and alkali, however performed, resulting in the formation of an
alkaline plumbite or plumbate and being followed by exposure of the mixture to the
air whereby the alkaline plumbite or plumbate is decomposed by atmospheric
carbonic acid with the formation of an alkaline carbonate and precipitation of oxide
or carbonate of lead. This chemical action has the effect of causing the setting of
the mass of lead oxide so as to obviate its subsequent disintegration.
"
With a view to increase the porosity of the plate when set, I may add to the
solution of caustic alkali a salt such as sulphate of potash or soda which deposits in
crystals on the drying of the mass by exposure to the air and becomes dissolved out
by the subsequent immersion of the mass. In any case, the mass, after having
set as above described, may advantageously be immersed in a solution of a
sulphate salt preferably sulphate of magnesia, the immersion being preferably
repeated, after intervals for drying, one or more times for successively longer periods.
The effect of the immersion is to form some sulphate of lead in the mass, which
tends to harden it and to cause the alkali to enter into combination with sulphuric
acid whilst the carbonic acid combines with the base of the sulphate salt, so that
the operation is unattended by the violent evolution of carbonic acid which occurs
when the set plate is immersed in dilute sulphuric acid, this violent evolution
tending to cause the disintegration of the mass. Masses of the material so prepared,
are respectively peroxidized and reduced to spongy lead by electrolytic action as is
well understood.
Dated this 17th dox of Max 1893
D. G. FITZ-GERALD,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents

page_text: COMPLETE SPECIFICATION.
Improvements in the Manufacture of Elements or Electrodes for
Voltaic Batteries and Electrolytic Decomposition Cells.
I, DESMOND GERALD FITZ-GERALD, of 94, Loughborough Road, London,
S.W. Electrician, 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 :-
"
My invention relates to an improved method of producing elements or electrodes
for voltaic batteries and electrolytic decomposition cells from an oxide of lead,
or a mixture of different oxides of lead, by causing the moistened lead oxide or
oxides to "set so as to be no longer liable to become disintegrated when
immersed in an aqueous liquid as is necessary in the subsequent operation of
converting the set material into dense, bard, and coherent peroxide of lead or
spongy lead, as the case may be.
It has heretofore been proposed to bring about this setting of moist lead oxide
by the action of a salt such as sulphate of ammonia or sulphate of lead.
It is the object of my present invention to obtain a better result than can be
obtained by the use of either of the above mentioned salts, the superiority of
the present method being due to the fact that the "set" product is more homo-
geneous and more porous and at the same time is stronger and especially that
it is capable of being "formed or converted into peroxide of lead in a very
much shorter time and with a very much smaller expenditure of electrical energy
than has hitherto been necessary when the product has been caused to "set" by
means of any salt heretofore used.
"
و"
My present invention consists essentially in the treatment of the monoxide of
lead (litharge or massicot), or of minium (or of a mixture of these oxides with
one another or with peroxide of lead) by caustic fixed alkali in the presence
of water, thereby forming some alkaline plumbite in the mass, and in the subse-
quent exposure of the moulded mass to an atmosphere containing carbonic acid
whereby the alkaline plumbite is decomposed with the formation of an alkaline
carbonate and precipitation of an oxide of lead. This chemical reaction within
the mass has the effect of causing the setting of the entire mass of lead oxide
so as to obviate its subsequent disintegration when immersed in an aqueous
solution. The moulded mass after having "set as above described, may advan-
tageously be treated (by immersion or otherwise) with a solution of a sulphate
salt, preferably sulphate of magnesia, the treatment being preferably repeated,
after intervals for drying, one or more times for successively longer periods.
The effect of this treatment is to form some sulphate of lead in the "set mass
which tends to harden it. A further effect of the treatment is to dissolve the
alkali (both caustic and carbonated) out of the mass and cause it to simul-
taneously combine with sulphuric acid whilst the carbonic acid combines with
the base of the sulphate salt, so that the operation is unattended by the violent
evolution of carbonic acid (and consequent tendency to disintegration of the mass)
which would occur were the set plate to be immersed in dilute sulphuric acid
without the previous removal of the carbonated alkali. The moulded masses of the
material so prepared may then be respectively peroxidised and reduced to spongy
lead by electrolytic action in the ordinary way.
"
The following are examples of the modes in which I prefer to carry my
invention into effect :
A.-I mix litharge, or massicot, or minium, or a mixture of them, with a solution
of caustic potash (or with a mixed solution of caustic potash and caustic soda)
having preferably a specific gravity of from 1100 to 1150. Caustic soda alone
might be used, but is undesirable by reason of the subsequent efflorescence of the
sodic carbonate formed. If used in admixture with caustic potash the latter

page_text: should be in the larger proportion to avoid excessive efflorescence. The quantity
of solution used should be sufficient to form the lead oxide or oxides into a stiff
paste which is then moulded in the ordinary way into plates or into masses of any
other desired form under a degree of pressure which need not exceed that
obtainable with an ordinary hand screw press. Such plates or masses may have
any suitable conductor embedded in them in the process of moulding, or a suitable.
The
conductor may be subsequently attached to the moulded plates or masses.
moulded plates or masses are then exposed to an atmosphere containing carbonic
acid (preferably to a current of air containing the full normal or an increased'
percentage of carbonic acid) for a sufficient period to convert a considerable per-
centage of the alkali into carbonated alkali. Experience with ordinary air has
shewn that an exposure for three days is sufficient, but when convenient this period
of exposure may advantageously be extended. The effect of this exposure is.
partially to dry the plates or other masses and by the conversion of the caustic
into carbonated alkali, to precipitate the oxide of lead previously held in solution.
When such precipitation has occurred to a sufficient extent, the material "sets"
and will no longer disintegrate when immersed in an aqueous fluid. The set plates
or masses are then dipped for a few seconds in a solution of sulphate of magnesia
which may be half-saturated or more dilute. This dipping should be at least twice.
repeated at intervals of a day or more and be dried by exposure to air after each.
immersion. The sulphate solution used for the last immersion should be more
dilute than the preceding solutions and should be slightly acidulated with sulphuric
acid and the plates may advantageously be left for some hours in this acidulated
solution with a view to dissolve out precipitated magnesium hydrate. The plates
or masses should afterwards be stood in a rack to drain and dry, and become.
❝ seasoned."
The plates or masses may be reduced to spongy lead or peroxidised by the-
ordinary means, but I prefer to use a method which forms the subject of another
application for Letters Patent made by me under date the 17th day of June 1893
and numbered 11983.
B. A modification of the above process adapted for the production of plates of
greater porosity, is to subject litharge, or inassicot, or minium, or a mixture of
them, preferably in a slightly damp condition, to pressure in a mould between
sheets of a material, such as linen or felt, containing enough moisture to cause the
surface particles of the lead oxide or oxides to cohere sufficiently to allow of the
subsequent treatment of the moulded mass (either within the mould or otherwise
supported as by a plate of glass) with an alkaline solution such as is above specified,.
the treatment in this case being conveniently effected by gently pouring a sufficient
quantity of the caustic solution over the moulded mass. The subsequent steps in
this process-i.e. exposure to carbonic acid and treatment with sulphate solution-
are similar to those above described.
C. In a third process, a mixture of any one or more of the lower oxides of
lead with peroxide of lead is used which may contain 25% or more of the latter
ingredient. The mixture may either be made into a paste with the caustic solution
or be moulded dry and moistened with the caustic solution as in the methods above
mentioned. In this case the treatment with the alkaline solution causes the plate
or mass to quickly set into a hard porous condition, even without the intervention
of carbonic acid, so that exposure to that gas for a longer period than a few hours
and subsequent treatment with sulphate of magnesia are not in this case essential.
It is to be observed that the proportion of peroxide contained in the mixture to
be treated may be such that the process becomes practically one for the utilization
of peroxide of lead whether produced chemically or electrolytically. I preter,
however, that the proportion of the lower oxide present should not be less than,
say, 10% or thereabouts, in order to produce with certainty the setting" effect
desired.
The plate or mass being initially conductive is, for this reason as well as from

page_text: the fact that it may be regarded as partly "formed," rapidly convertible wholly
into peroxide by the passage of the current.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I would observe that I have
given the above processes as examples of the mode in which I usually carry my
invention into effect, but I do not limit myself thereto, and I declare that what I
claim is―
In the manufacture of elements or electrodes for voltaic batteries, and electro-
lytic decomposition cells, the production of dense, coherent, non-disintegrating
masses mainly composed of an oxide of lead, or a mixture of oxides of lead, by
treating such oxide, or mixture of oxides, with a solution of the hydrate or
hydrates of one or both of the fixed alkalies and converting the caustic alkali
into carbonated alkali by exposure to an atmosphere containing carbonic acid.
Dated this 15th day of November 1893.
D. G. FITZ-GERALD,
By A. M. & Wm. Clark,
53, Chancery Lane, London, Chartered Patent Agents.