IMPROVEMENTS IN THE MANU- FACTURE OF WHITE LEAD AND OTHER LEAD SALTS, AND APPARATUS EMPLOYED THEREIN, PARTS OF WHICH ARE APPLICABLE TO OTHER MATERIALS." PROVISIONAL SPECIFICATION
Year: 1879

page_text: LETTERS PATENT to Jolin Cowdery Martin, of 5, Upper Hill Street, Richmond,
in the County of Surrey, for the Invention of "IMPROVEMENTS IN THE MANU-
FACTURE OF WHITE LEAD AND OTHER LEAD SALTS, AND APPARATUS EMPLOYED
THEREIN, PARTS OF WHICH ARE APPLICABLE TO OTHER MATERIALS."
PROVISIONAL SPECIFICATION left by the said John Cowdery Martin at the
Office of the Commissioners of Patents on the 18th March 1879.
JOHN COWDERY MARTIN, of No. 5, Upper Hill Street, Richmond, in the County of
Surrey. "IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD AND OTHER LEAD
SALTS, AND APPARATUS EMPLOYED THEREIN, PARTS OF WHICH ARE APPLICABLE TO
OTHER MATERIALS."
I produce solutions of lead salts by dissolving with a suitable solvent splashes of
metallic lead formed by dropping lead in a melted condition upon a cold dry fixed
or moving surface of sufficient hardness to flatten the drops as they fall. I also
dissolve for the same purpose finely granulated lead formed by the melted drops
falling on a similar surface in a wet condition, which scatters the splash in the state
of coarse dust, and I precipitate white lead by means of carbonic acid from the
solution formed by dissolving such lead splashes or granulations.
I mix hydrated oxide of lead with the white lead precipitated from a solution of
lead salt by carbonic acid gas, or that is produced in a wet condition; and I mix
this oxide with the white lead while the latter is wet, and I grind the mixture
when dry for the purpose of increasing the specific gravity or density of the white
lead and improving its quality as a paint. In place of the hydrated oxide I also
use for the same purpose the suboxide of lead or the oxide produced in combination
with the lesser proportions of oxygen and formed at low temperatures.
I separate from water or from a solution bydrated oxide of lead or white lead
produced by precipitation by means of a trough divided by partitions into a long
continuous gutter having other divisions across its length, and along and over
which the solution carrying the material in suspension travels and deposits it in its
passage.
For mixing or grinding together the lead oxide with the white lead in a dry
condition I use the ordinary edge runner stones, and the dust produced being

page_text: extremely poisonous and deleterious to health I enclose them with a casing and
avoid the use of manual labour in presense of the poisonous lead dust by making
them as nearly self acting as possible. I keep the material well under the stones
by fitting them with the ordinary scrapers made somewhat longer than usual, and
I throw the material out after sufficient grinding or mixing by means of a suitably
curved scraper attached by a rod to a lever, the inner end of which is secured by a
pin or joint, the outer end being fitted with a wheel which runs on and is supported
by a circular plate or tramway fixed without the stones, and which keeps the
scraper suspended above the material under treatment. A part of this tramway is
hinged and is made to rise and fall. by means of a chain passing through the casing,
and when the end of the hinged part lifted an opening is formed in the circular
tramway, and the wheel carrying the lever on reaching this falls and passes under
it; the scraper then rests on the bed of the apparatus immediately throwing out
the material through an opening provided for that purpose. When this is effected
the hinged part of the plate or tramway is lowered by means of the chain and
forms an inclined plane which the wheel carrying the lever ascends, on coming in
contact with lifting the scraper into its original position above the material when
the hinged plate is fixed level, as before.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said John Cowdery Martin in the Great Seal Patent Office on the 18th
September 1879.
JOHN COWDERY MARTIN, of 5, Upper Hill Street, Richmond, in the County of
Surrey. "IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD AND OTHER LEAD
SALTS, AND APPARATUS EMPLOYED THEREIN, PARTS OF WHICH ARE APPLICABLE TO
OTHER MATERIALS."
These improvements are in part founded upon those described in the Specification
of former Letters Patent granted to me, and dated the Fourth day of April, A.D.
1877, Number 1300.
The first part of my Invention relates to the production from splashes of lead
formed, as hereinafter described, of solutions of lead salts, and for this purpose I
dissolve by means of solvents suitable to produce the desired solutions very small
flakes or splashes of metallic lead or granulated lead which are formed by dropping
thin streains of molten lead upon a cold stationary or moving surface of sufficient
hardness to flatten the drops of molten lead as they fall, and which are kept in a
wet state. By preference this surface may be formed of cast iron. In the Specifi-
cation of my former Patent I in particular referred to the surface of a hollow cast
iron cylinder as being the form of the surface suitable for being used, but, as is
obvious, other forms of surface may be employed both in a dry state, and, as I have
discovered since the date of the said Patent, with still greater advantage in a wet
state. For example, I use a hollow revolving disc or cone if the surface is to be
moved, as illustrated in Figures 1 and 2 of the Drawings, or, if stationary, the
surface may be raised or inclined so that it may the more readily throw off the
drops of molten lead falling upon it, as illustrated in Figure 3. I keep these
surfaces cool whether moving or stationary by means of water caused to pass
beneath, through, or behind them. The surfaces should be kept wet by jets or
sprays of water falling upon them, or by the occasional immersion of the surfaces
into water for the purpose of producing the aforesaid very small splashes of lead or
granulated lead; and when found necessary fixed scrapers may be employed to
prevent the said splashes of lead or granulated lead from adhering to the moving
surfaces, as shewn in Figure 1; or scrapers moved by any suitable means may be
used for the same purpose in connexion with stationary surfaces.
I dissolve the lead reduced to splashes or granulated, as above described, in the
ordinary way by causing a solution of acetic or nitrous acid or other suitable
solvent to flow over it while freely exposed to the atmosphere upon perforated
trays composed of wood or other suitable material; or I agitate it in contact with
the solution and with the atmosphere by means of revolving agitators; or I dissolve
it in any other convenient manner.
The second part of my Invention consists in mixing hydrated oxide of lead, or
the suboxide of lead or the oxide produced by combination with the lesser
proportions of oxygen and formed at low temperatures with white lead precipitated
from a solution of lead salt by carbonic acid gas, or that is produced by other
means. I mix this hydrated oxide or suboxide of lead, as the case may be, with
the white lead while the latter is wet, and I grind or crush this mixture when dry,
adding or not, as may be necessary, a further proportion of oxide during the
grinding operation. The object of this mixture of oxide of lead with white lead is
to increase the specific gravity or density of the white lead, and to improve its
quality as a paint, as described in the Specification of my aforesaid Patent, Number
1300; but the distinctive feature of this part of my present Invention consists in
effecting the mixture whilst the white lead is in the wet state; and I find it
advantageous to add the oxide of lead while there still remains a small proportion
of the lead solution, as by that means the white lead resulting is in some cases of a

page_text: smoother quality than when water only is present, whereas by the process described
in the Specification of the aforesaid Patent Number 1300, the mixture is effected
after the white lead has been dried. By effecting the mixture whilst the white
lead is wet I have found that better results are obtained than when the mixture is
effected in the dry state.
The hydrated oxide of lead may be made as described in the Specification of the
aforesaid Patent Number 1300, that is to say, by the abrasion of granulated
metallic lead exposed to the action of water and of the atmosphere, and the sub-
oxide of lead by gently heating white lead in a closed retort; and those are the best
means with which I am acquainted for producing those substances, but they may
be produced by other means if preferred.
For the purpose of separating white lead from a solution of lead salt produced
by dissolving metallic lead in a suitable solvent I employ a trough divided by
partitions into a long continuous gutter having divisions across its length. The
solution carrying the materials in suspension travels along the gutter and over the
divisions therein, depositing the said materials in its passage. Figure 4 of the
Drawings shews a side view, Figure an end, and Figure 6 a plan of the trough
with which I separate the white lead from the solution. a, a, a, in the several
Figures shew partitions across the long continuous gutter into which the trough is
divided, which partitions arrest the deposit as it falls, the remaining solution
flowing over the said cross partitions. I make no claim to this method of separation
as forming by itself a part of my present Invention.
Another part of my present Invention relates to the following improved arrange-
ments in connexion with the apparatus for grinding together the lead oxide and
the white lead in a dry condition. When I employ the ordinary edge runner stones
for this purpose, the dust produced being extremely poisonous and deleterious to
health, I enclose these edge runners within a casing and avoid the use of manual
labour in presence of the poisonous lead dust by making the apparatus nearly self
acting. Figures 7 and 8 shew an edge runner enclosed as described, the materials
being fed in through the opening a in the side of the casing. I keep the material
well under the stone or stones by fitting it or them with the ordinary scrapers,
made by preference somewhat longer than usual; and I throw the material out
after sufficient grinding or mixing by means of a suitably curved scraper b attached
by a rod c to a lever d, the inner end of which is secured by a pin or joint e, the
outer end being fitted with a wheel or friction roller f, which runs on and is
supported by a circular plate or tramway g fixed outside the stone or stones to the
inside of the casing or in any other convenient position, and which keeps the
scraper suspended above the material under treatment. A part h of the
tramway g is hinged at i, and is made to rise and fall by means of a chain, rod, or
cord passing through the casing. When the end of the hinged part h is lifted, as
shewn at Figure 7, an opening is formed in the circular tramway, and the wheel or
friction roller f, with the end of the lever d, on reaching this opening fall and pass
under it, and the scraper b then rests on the bed of the apparatus, throwing out as
it revolves with the stone or stones the material through an opening provided for
that purpose in the usual way. When this is effected the hinged part of the
plate or tramway 9 is lowered by means of the chain, rod, or cord k, and forms an
inclined plane, as shewn at Figure 8, which the wheel or friction roller f, with the
end of the lever d, ascends on coming in contact with it, lifting the rod c and the
scraper b into their original positions above the material. The hinged plate h being
then raised and held level with the rest of the circular plate or tramway the wheel
or friction roller f travels round and round on the same, keeping the scraper b
raised until the hinged part h is again raised, as in Figure 7.
Enclosed edge runners fitted with the scrapers and apparatus herein described
may be used for mixing or grinding materials other than white lead, the dust or
fumes of which it is desired shall not escape into the atmosphere.
Having now described the nature of the said Invention, and the manner in

page_text: which the same is to or may be carried into effect, I would have it understood that
what I claim as my Invention is,―
Firstly. The manufacture of solutions of lead salts by dissolving small splashes
of metallic lead or granulated metallic lead produced by the employment of a
stationary or moving wetted surface kept wet by jets or sprays of water, or by
occasional immersion into water, substantially as hereinbefore described.
Secondly. Mixing in a wet condition hydrated oxide of lead or the sub-oxide of
lead with precipitated or other white lead that requires to be improved in quality as
a paint, and grinding or crushing the mixture when in a dry condition with or
without the addition of a further quantity of the hydrated oxide or the sub-oxide
of lead for the purpose of increasing the specific gravity or density of the white
lead and improving its quality as a paint, as hereinbefore described.
Thirdly. The employment in connexion with enclosed edge runner grinding
stones of a curb or rail g with a hinged piece h in combination with a lever d and
roller for their equivalents operated as described for the purpose of raising and
lowering the discharging scraper b, substantially as herein before described and
illustrated in Figures 7 and 8 of the Drawings.
In witness whereof, I, the said John Cowdery Martin, have hereunto set my
hand and seal, this Seventeenth day of September, in the year of our
Lord One thousand eight hundred and seventy nine.
J. C. MARTIN. (L.S.)