An Improved Method for the Production of Coherent Masses of Peroxide of Lead for Use as Voltaic Battery Elements, and for Use in Electrolytical and Metallurgical Operations.
Year: 1886

page_text: Date of Application, 17th Dec., 1886
Complete Left, 15th Oct., 1887
Complete Accepted, 2nd Dec., 1887
An Improved Method for the Production of Coherent Masses of
Peroxide of Lead for Use as Voltaic Battery Elements, and for
Use in Electrolytical and Metallurgical Operations.
I, DESMOND GERALD FITZ-GERALD of 6, Akerman Road Brixton in the County
of Surrey Electrician do hereby declare the nature of this invention to be as
follows:-
-
My Invention relates to a method of obtaining peroxide of lead in coherent masses
for use in voltaic batteries, and for other purposes. Various mixtures of theoxides of
lead with each other and with an insoluble salt of the metal have heretofore been
employed in the production of voltaic elements, such mixtures in a plastic form
being applied to the surface of a conductor, ordinarily of lead, or permanently
enclosed within a rigid frame, and afterwards converted electrolytically into spongy
lead or into lead peroxide. In the latter case, the contact of the peroxide with an
oxidizable conductor is very detrimental, since the two substances, in presence of
moisture, tend to re-act upon and mutually destroy each other. This objection applies
both when the peroxide enters into the composition of a voltaic element and when it
is to be utilized for other purposes o.g. as an anode in the generation of chlorine by
the electrolysis of a soluble chloride. Moreover when the mixture to be converted
into peroxide of lead is confined within a rigid frame, the free expansion of the
material during such conversion is prevented and the disintegration of the converted
material is thus brought about.
My Invention consists in the production of coherent masses, moulded to any
desired form, from mixtures composed of one or more of the oxides of lead with an
insoluble or nearly insoluble salt of lead without such masses being applied to the
surface of an oxidizable conductor such masses, whilst free to expand. by the effect of
such conversion, being afterwards converted wholly or in part into peroxide of lead
by a chemical or by an electrolytic process or by a combination of both processes, as
is well understood.
In carrying out my Invention, I mix monoxide of lead with an insoluble or nearly
insoluble salt of this metal, and form the mixture into a plastic mass with water

page_text: whereby I produce a gradual "setting" of the mass after it has been moulded, and
thus obviate its disintegration when it is subsequently immersed in a fluid. This
"setting" which is a necessary condition for the production of coherent masses of
peroxide of lead is due to a re-arrangement of the molecules in the moulded mass
consequent upon the formation of a sub-salt or basic salt of lead by a chemical com-
bination occurring between a normal salt and the monoxide of this metal. The
addition to the above mixture of a certain proportion of peroxide of lead (preferably
the hydrated form as obtained by electrolysis) not only promotes the "setting" of the
moulded mass but also augments its conductivity, thereby facilitating the conversion
of the mass into peroxide of lead.
In order to obviate the partial "setting" of the plastic mixture prior to its being
moulded, it is sometimes advantageous to place the dry mixture of a salt of lead
with excess of the monoxide of this metal (with or without the addition of lead
peroxide) in the mould and afterwards to moisten the mixture, either by the
immersion of the mould in water, or by means of a jet of water-spray, or by steam.
The moulded plates, or the masses of material brought to the required form, should
be allowed to dry gradually before being subjected to further treatment with a view to
their complete conversion into peroxide of lead.
Dated this 17th day of December 1886.
D. G. FITZ-GERALD.
By A. M. & Wm. Clark,
53, Chancery Lane, London,
Patent Agents.

page_text: An Improved Method for the Production of Coherent Masses of
Peroxide of Lead for Use as Voltaic Battery Elements, and for
Use in Electrolytical and Metallurgical Operations.
I, DESMOND GERALD FITZ-GERALD of 6 Akerman Road Brixton in the County of
Surrey, 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 the manufacture of peroxide of lead in dense yet porous
coherent self-supporting masses (or what is known as "lithanode") for use in voltaic
batteries, and for other purposes.
Various mixtures of peroxide of lead with non-conducting lead compounds, have
heretofore been proposed for the production of voltaic elements, such mixtures in a
plastic form being intended to be applied to the surface of a conductor ordinarily of
metallic lead, or permanently enclosed within a rigid frame wholly or partly of lead ;
the substances added to the peroxide of lead being intended to be afterwards con-
verted electrolytically into this compound. Now, the contact of the peroxide with an
oxidizable conductor in presence of moisture would be very detrimental, since the two
substances under those circumstances tend to re-act upon and mutually destroy each
other. Moreover, if the mixture to be converted into peroxide of lead were confined
within a rigid frame, the free expansion of the material during such conversion would
be prevented and the disintegration of the converted material thus brought about.
Monoxide of lead has also been mixed with a solution of an ammonia salt in order to
produce dense and coherent plates, masses, and layers convertible by electrolysis into
peroxide of lead, as described in the specification of a former patent granted to me
dated April 15th 1885, No. 4671.
My invention consists in the prodnction of dense yet porous, coherent, and self
supporting plates or masses wholly or almost wholly convertible into peroxide of lead
by mixing monoxide of lead (with or without an admixture of peroxide of lead) with
an insoluble or nearly insoluble salt of lead, such plates or masses being afterwards
converted wholly or in part into peroxide of lead (without such masses being
permanently in contact with the surface of an oxidisable conductor or rigidly con-
fined within a frame) by an electrolytic, or preferably, by a combined chemical and
electrolytic process, the masses having the necessary freedom for expansion by the
effect of such conversion.
In carrying out the invention I prefer to mix monoxide of lead with an insoluble
or nearly insoluble salt of this metal (preferably the sulphate of lead) and form
the mixture into a plastic mass with water whereby the mass is caused to gradually
"set" after it has been moulded to the desired form. I thus obviate its disintegra-
tion when it is subsequently immersed in a fluid. This "setting" which is a
necessary condition for the production of coherent masses of peroxide of lead, is due

page_text: to a rearrangement of the molecules in the moulded mass consequent upon a chemical
combination occurring, in presence of moisture, between the normal salt and the
monoxide, the result of this combination being a sub salt or basic salt of lead. The
addition to the above mixture of a certain proportion of hydrated peroxide of lead
as obtained by electrolysis angments the conductivity of the moulded mass, thereby
facilitating the conversion of the whole mass into peroxide of lead.
It is to be noted that commercial peroxide of lead will not answer so well as peroxide
which has been produced by electrolysis the usual source of which is broken or
damaged negative plates which have been used in batteries and which only require
to be ground up fine to be fit for the present purpose.
As an example of my process, I take four parts by weight of monoxide of lead
(litharge) and one part of sulphate of lead and bring the ingredients in the condition
of fine powder into intimate admixture. Sufficient water is then added to, and
thoroughly incorporated with, the mixture so as to produce a plastic mass which may
be moulded in the form of plates in any suitable construction of mould-for example
that described in the specification of former Letters Patent granted to me and dated
the 15th day of April 1885 No. 4671. The moulded plates are then superficially
peroxidized or "browned" by immersion in a hot solution of an alkaline or carthy
hypochlorite as described in my aforesaid specification, (of which I will here repeat
the part relating to the "browning" process) and finally are electrolytically converted
throughout into peroxide.
I prefer to use chloride of soda (sodic hypochlorite) or chloride of magnesia
(magnesic hypochlorite) which may be obtained by decomposing a solution of chloride
of lime by means of sodic carbonate or magnesic sulphate. But, in operating on a
large scale, I economically generate and utilize the magnesic hypochlorite as follows ;-
I pass chlorine gas into the lower part of a tank containing hot water in which the
plates to be converted are supported, preferably edgeways, and at a small distance
apart. The plates preferably rest on a perforated falso bottom beneath which is placed
a quantity of calcined magnesite or other form of magnesia in powder, into the midst
of which the chlorine is introduced by perforated stoneware tubes or other suitable
nieans. The tank and false bottom are preferably made of stoneware or slate. The
magnesia gradually becomes dissolved by reason of its conversion into hypochlorite
and chloride of magnesium. It is necessary that the operation should not be con-
tinued after the magnesia is wholly dissolved, without adding a fresh supply. Heat
may be applied by blowing in steam and the hot solution of magnesic hypochlorite
effects a rapid and more or less superficial conversion of the surface of the plates
into peroxide of lead, the depth of the conversion increasing with the porosity of the
plates.
The proportions may be varied by taking three parts of the monoxide to one part of
the sulphate of lead. By adding electrolytically produced peroxide of lead to the
above mixture (say in the proportion of one part by weight of peroxide to two parts
of litharge and one part of sulphate) the plates are rendered more conductive and the
operation of "browning" or superficial conversion into peroxide as above mentioned
is not essential.
It is to be understood that the proportions above mentioned are those which I have
found to answer, and that I do not limit myself thereto.
Chloride or phosphate of lead may be substituted for the sulphate, but I have found
the sulphate to be by far the most advantageous in practice.
In order to obviate the premature "setting" of the plastic mixture and ensure greater
homogeneity, the mixture of oxide or oxides, and sulphate or other insoluble or nearly
insoluble salt of lead may be placed in the mould when in a dry state and be after-
wards moistened either by immersion in water or by the application of a jet of
water-spray or by steam.
The moulded plates, or the masses of material brought to the required form, should
be allowed to dry gradually after removal from the mould, before being subjected to
further treatment with a view to their complete conversion into peroxide of lead. The
period of drying which is required is not so lengthy as that necessary in the process

page_text: described in the specification of my former Patent aforesaid, a few hours exposure to
dry air being sufficient.
Having now particularly described and ascertained the nature of the said Inven-
tion and in what manner the same is to be performed, I declare that what I
claim is
-
1. In the production of peroxide of load for the purposes specified, the heroin
described process of producing dense, porous, coherent, and self-supporting plates or
masses wholly or almost wholly convertible by electrolysis into peroxide of lead,
which process consists essentially in mixing monoxide of lead (litharge) with an in-
soluble salt of lead such as the sulphate, and in causing by the application of
moisture-chemical action between the ingredients of such mixture, whereby the
mixture is caused to "set," as described.
2. In the production of peroxide of lead for the purposes specified, the herein
described process of producing dense, porous, coherent, and self-supporting plates or
masses wholly or almost wholly convertible by electrolysis into peroxide of lead, which
process consists essentially in mixing monoxide of lead (litharge) with an insoluble salt
of lead such as the sulphate, and in causing-by the application of moisture-
chemical action between the ingredients of such mixture, whereby the mixture is
caused to "set; " then superficially peroxiding the plate or mass by means of
chlorine, in the manner described.
3. In the production of peroxide of lead for the purposes specified, the herein
described process of producing dense, porous, coherent, and self-supporting plates or
masses wholly or almost wholly convertible by electrolysis into peroxide of lead, which
process consists essentially in mixing monoxide of lead (litharge) and peroxide of lead
(preferably that obtained by electrolysis) with an insoluble salt of lead such as the
sulphate, and in causing by the application of moisture-chemical action between
the ingredients of such mixture, whereby the mixture is caused to "set"; the
plates thus produced being, by reason of the conductivity of the added peroxide of
lead, readily convertible by electrolysis into peroxide of lead without previously
undergoing the superficial peroxidation by the agency of chlorine.
Dated this 15th day of October 1887.
D. G. FITZ-GERALD.
By A. M. & Wm. Clark,
53, Chancery Lanc, London,
Patent Agents.