Improvements in the Manufacture of White Lead.
Year: 1893

page_text: COMPLETE SPECIFICATION.
[Communicated from abroad by ARTHUR BENJAMIN BROWNE, of Cambridge, in
the County of Middlesex and State of Massachusetts, United States of
America, Chemist.]
Improvements in the Manufacture of White Lead.
I, HENRY HARRIS LAKE, of the firm of Haseltine Lake & Co., Patent Agent,
45 Southampton Buildings, in the County of Middlesex, 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 white lead.
The process of manufacturing white lead hereinafter described, is, I believe,
radically new, and altogether unlike any process heretofore practised.
By means of my invention, white lead may be produced in much less time and
with a material reduction in the cost of manufacture, as compared with the best
processes now in general use.
My invention consists in placing a body of metallic lead to be acted upon, in a
solution of a nitrate or acetate of an alkaline base, which, under the influence of
an electric current, will separate into a solvent of lead at one pole, and an alkaline
hydrate at the other pole, and simultaneously electrolyzing the said solution by
causing a current of electricity to flow from the metallic lead through said solution,
whereby a lead hydrate is precipitated; and finally allowing the said lead hydrate
to dry in the air or other atmosphere containing carbonic acid.
My invention further consists in placing the metallic lead to be acted upon in
a suitable vessel, and in electric connection with the positive side of a source of
electric force to form the anode of the bath, causing a solution of a nitrate or
acetate of an alkaline base which, under the influence of an electric current, will
separate into a solvent for lead at the anode, and an alkaline hydrate at the cathode,
to flow into said vessel and over and around said metallic lead until said anode
and cathode are submerged, causing a current of electricity to flow from said anode
through said solution, to produce the reactions necessary to dissolve said anode and
form a soluble salt of lead; causing said salt of lead to be precipitated to form a
lead hydrate; causing the said solution, holding in suspension the lead hydrate, to
flow into the settling tank or vessel; allowing the lead hydrate to settle; drawing
off the solution from which the lead hydrate has been precipitated; and then
exposing it to an atmosphere containing carbonic acid and allowing it to dry, when
it is ready to be ground in oil and placed upon the market.
In the accompanying drawings,
Figure 1 is a vertical section through portions of three floors of a building and
parts of the apparatus for carrying out my improved process, other parts being
shown in elevation.
Figure 2 is a plan of the electrolyzing tank, with the cathode and the metallic
lead which forms the anode removed.
For the proper working of my improved process I employ a supply tank A,
having a discharge pipe a opening from its bottom, and provided with a valve 6 to
control the delivery through said pipe. A second tank B is arranged, preferably at
a lower level than the tank A, in a convenient position to receive the discharge from
said tank A, through its bottom by means of the induction pipes a¹, a', commu-
nicating with the pipe a as shown.
The bottom of the tank B is preferably made inclined in all directions toward
the centre, and it is also provided with the grating c above said inclined bottom,
upon which is placed the skeleton frame d, made of aluminium or other suitable

page_text: conducting and acid proof material, which is connected by the wire e to the positive
side of a dynamo D, or other suitable source of electric force.
The tank B is provided with a discharge pipe f opening from the centre of its
bottom, and extending to and discharging into the settling tank or vessel C,
arranged preferably at a lower level than said tank B, the said pipe f having a
valve for controlling the flow of the liquid from the tank B to the tank C.
The tank B has adjustably suspended therein, at a suitable distance above the
grating c and the skeleton frame d, the cathode g, the body of which is preferably
made of wood covered on its under side with a plate of lead in contact with the
eyebolt or other means of suspension, which is connected by the wire i to the
negative side of the dynamo D or other source of electric force.
In working my improved process I charge the supply tank A with a solution
of a nitrate of an alkaline base, preferably nitrate of soda dissolved in water,
though a solution of an acetate of an alkaline base may be used with a fair degree
of success if desired.
The metallic lead to be operated upon is placed upon the skeleton framed as
shown at j, and becomes the anode of the electric circuit, and then the valve bis
opened to allow the solution in the supply tank A to flow into the electrolyzing
tank B until the anode and cathode are submerged in said solution, the valve f
in the meantime remaining closed.
The electric circuit is now closed, causing a current of electricity to flow through
the anode and the solution to the cathode, which immediately causes reaction to
take place and the salt or salts of the solution to be decomposed into nitric acid
and alkaline hydrate, the acid going to and dissolving the anode to form a soluble
salt of lead, while the alkaline hydrate accumulates around the cathode until
disturbed by the flow of the solution towards said cathode, which causes said
alkaline hydrate to mix with the soluble salt of lead thereby precipitating hydrate
of lead.
When these reactions have fairly commenced, the valve f¹ is opened to allow the
solution, holding the hydrate of lead in suspension, to flow into the settling tank C,
where, after a while, the said lead hydrate will settle at the bottom of said tank
leaving the solution in the upper portion of said tank clear, and in substantially its
original condition, and fit to be transferred to the supply tank A and used over
again.
To accomplish this transfer I employ a pump E, provided with the suction pipe k
and the delivery pipe l, of any well known construction.
The lead hydrate produred as above described possesses the property of rapidly
absorbing carbonic acid gas from the air, which it commences to do as soon as the
solution is drawn off, thereby forming a hydrated carbonate of lead.
If the absorption from the air should not prove rapid enough for commercial
purposes, the hydrated lead may be exposed to an atmosphere of carbonic gas
generated artificially by any well known means, such, for instance, as the action of
an acid upon marble dust.
While I have shown and described the metallic lead, which serves as the anode
of the electric circuit, near the bottom of the tank with the cathode above it, and
the pipe or pipes for delivering the solution from the supply tank to the electro-
lyzing tank, entering said tank at its bottom which is the arrangement I prefer as
being the most convenient, I do not wish to be confined to this particular
arrangement, as the positions of the anode and cathode may be reversed, or they
may be placed at opposite sides of the tank, care being taken that the current of
electricity and the inflowing current of the solution entering said electrolyzing tank
shall move substantially in the same direction therein.
Neither do I wish to be confined to the use of a solution of a nitrate of an alkaline
base, as I may use any other salt which is separated by electrolysis into a solvent
for lead at one pole, and an alkaline hydrate at the other, as for instance, an
acetate of an alkaline base. In the use of an acetate of an alkaline base the
reaction caused by the flow of the electric current through the solution from the

page_text: anode to the cathode, will be a separation of the solution into acetic acid and an
alkaline hydrate; the acid will go to and attack the anode and dissolve the same,
forming lead acetate, and the alkaline hydrate will accumulate, as before described,
around the cathode, and being mixed with the lead acetate by the agitation of the
solution, caused by the inflowing current, will precipitate lead hydrate as before
described, the process being substantially the same," whatever salt of this class is
used.
As, however, there are commercial and other objections to the use of the acetate
above described, I prefer the use of the nitrates herein before mentioned.
The solution may be composed of any single one of the salts before mentioned, or
of a combination of two or more of said salts if desired, without departing from the
principles of my invention.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
―:
1st. The process of manufacturing white lead which consists in placing a body
of metallic lead to be acted upon, in a solution of a nitrate or an acetate of an
alkaline base, which, under the influence of an electric current, will separate into a
solvent of lead at one pole, and an alkaline hydrate at the other pole, and simul-
taneously electrolyzing said solution by causing a current of electricity to flow from
the metallic lead through said solution, whereby a lead hydrate is precipitated, and
finally allowing said lead hydrate to dry in the air or other atmosphere containing
carbonic acid.
2nd. The process of manufacturing white lead, which consists in placing the
metallic lead to be acted upon in a suitable vessel, and in electric connection with
the positive side of a source of electric force to form the anode of the bath; causing
a solution of a nitrate or an acetate of an alkaline base, which, under the influence
of an electric current will separate into a solvent of lead at the anode, and an
alkaline hydrate at the cathode, to flow into said vessel and submerge said anode
and the cathode, causing a current of electricity to flow from said anode through
said solution to produce the reaction necessary to dissolve said anode and form a
soluble salt of lead; causing said salt of lead to be precipitated to form a lead
hydrate; causing said solution, holding in suspension the lead hydrate, to flow into
the settling tank or vessel; allowing the lead hydrate to settle; drawing off the
solution from which the lead hydrate has been precipitated; and then exposing
said lead hydrate to an atmosphere containing carbonic acid gas and allowing it to
dry.
Dated this 25th day of Apri
1030
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C., Agents for the Applicant.