AN IMPROVED PROCESS OF REFINING IMPURE LEAD, AND SEPARATING THERE- FROM GOLD, SILVER, AND OTHER METALS
Year: 1878

page_text: LETTERS PATENT to William Robert Lake, of the Firm of Haseltine, Lake, &
Co., Patent Agents, Southampton Buildings, London, for the Invention of
"AN IMPROVED PROCESS OF REFINING IMPURE LEAD, AND SEPARATING THERE-
FROM GOLD, SILVER, AND OTHER METALS." A communication from abroad
by Nathaniel Shepard Keith, of Brooklyn, New York, United States of
America, Chemist and Electrician.
PROVISIONAL SPECIFICATION left by the said William Robert Lake at the
Office of the Cominissioners of Patents on the 20th May 1878.
WILLIAM ROBERT LAKE, of the Firm of Haseltine, Lake, & Co., Patent Agents,
Southampton Buildings, London. "AN IMPROVED PROCESS OF REFINING IMPURE
LEAD, AND SEPARATING THEREFROM GOLD, SILVER, AND OTHER METALS." [A
communication from abroad by Nathaniel Shepard Keith, of Brooklyn, New York,
United States of America, Chemist and Electrician.]
The said Invention consists primarily in subjecting impure lead, or the ordinary
lead of commerce, to the process of electrolysis, that is to say, to the action of
solvents excited by electricity, wherein the impure lead is resolved into its
elementary constituents, the impurities are left undissolved, and the lead is at the
same time separated and deposited by itself in a purified form.
The said Invention embraces,-
The exposure of the lead to be dissolved to the action of an electric current, under
the conditions of an anode, in a suitable electrolyzing solution or bath.
Also, the use of such bath or solution for refining impure lead, aided by the action
of heat applied to the solution.

page_text: Also, the combination of a series of two or more baths with the same battery or
generator, and with each other, by electrically connecting the cathode of the first
bath of the series with tho anode of the second bath, and the cathode of the second
with the anode of the third, and so on.
Also, a bath composed of an acidulated solution of a salt of lead for the purposes
herein-after set forth.
Also, the double operation of separating the impurities from the lead, rendering
them easy of refinement, and at the same time obtaining metallic lead in a puro
state.
In carrying my Invention into practice I use a competent generator of electricity
in connection with a suitable bath, composed of an electrolyzing solution, into
which I introduce the lead to be treated, as the positive pole of the battery, and
any metallic or other clectric conductor as the cathode or negative pole.
For the bath I use solutions of some of the salts of lead. But in the action of
normal solutions of the neutral salts of lead, sub salts and oxides forin upon the 1
electrodes and in the solutions, thus decomposing the solutions and stopping the
electrolytic action by reason of the non-conducting coating on the electrodes and the
changed character of the solutions, in consequence of which the electrolytic action
gradually grows less, and often ceases altogether; and at best it is imperfectly
carried on in normal solutions. To overcome these difficulties I use solutions of s
acetate of lead, of chloride of lead, or of nitrate of lead, each made acid either by
acetic or hydrochloric acid; having ascertained by practical experience that this
acidulation prevents the said formation of sub-salts and oxides upon the electrodes,
whereby the electrolytic action remains unimpaired an indefinite length of time.
It is necessary to use solutions of salts of lead, which, under the exciting influence
of electricity, as applied in the electrolytic bath, do not dissolve gold, silver, and
other constituents of commercial impure lead, pig lead, or of lead known in the
market by the name of "base bullion" but will dissolve such lead. I therefore
employ the aforesaid solution or solutions of acetate, or chloride, or nitrate of lead,
made acid as described, having found that these readily dissolve the lead when
electrolytically treated, but do not dissolve the gold, silver, and other metals.
I uso various solutions, notably those of oxide of lead in solutions of caustic
potash, and caustic soda; but I prefer a solution of acetate of lead in water mado
acid by acetic acid.
I also prefer nearly saturated solutions, though almost any strength of solution
may be used.
Having prepared my bath by placing the solution in a proper vessel, I attach
some of the above-mentioned impure lead, preferably previously cast or rolled into
sheets, to the positive pole of a generator of electricity, and immerse it in the bath,
thus making it an anode. To the negative pole I attach a sheet or sheets of copper,
brass, lead, or other metal or carbon immersed in the bath, thus making it or them
the cathode. I procure the necesssary current of electricity from any source, but
preferably from magneto-electric or dynamo-electric machines, in well known ways.
As long as a current of electricity flows in this circuit, lead is dissolved from the
anode and deposited in a pure crystalline metallic form on the cathode, from which 4
it may be removed for melting into commercial shape, or otherwise utilized. Such
gold, silver, antimony, copper, tin, and the like as may be in the anode, remain
undissolved, and gradually drop off the surface of the anode in the shape of a fine
powder into properly placed receptacles, whence the powder may be removed for
subsequent refining or melting, or sale; or the anode may be placed in a bag of a
muslin or like material, which will retain the undissolved impurities so that they
inay be readily removed.
I increase the size and number of the electrolyzing baths to accord with the
necessary extent of the operation, and where a series of two or more baths for
electrolyzing lead are used, I arrange them so that the cathode of the first bath of 5
the series is electrically connected with the anode of a second bath, and the cathode

page_text: of the second bath is electrically connected with the anode of a third bath, and so
on through any number. This is a valuable method, for, though the resistance thus
added to the electric current decreases the current passing, and the amount of lead
dissolved and deposited in any one of the series, yet the aggregate amount of lead
dissolved and deposited is increased, with a corresponding decrease in the aggregate
consumption of zinc and acid in the galvanic battery connected therewith; or, if an
electrical machine be used, a corresponding decrease in the power used to drive it.
In this manner I effect a great saving in the cost of the electricity needed for
electrolyzing a large amount of lead. I have also found that by heating the
solutions I use for electrolyzing lead, their conductivity is much increased, so that
electric batteries or machines of much less electro-motive force may be used, thus
increasing the economy of this process.
As I prevent the formation of sub-salts and oxides on the electrodes and in tho
solutions, I obtain the full electrical equivalent of lead dissolved and deposited for
the electricity used, and the solutions are not decomposed.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Robert Lake in the Great Seal Patent Office on the 20th.
November 1878.
WILLIAM ROBERT LAKE, of the Firm of Haseltino, Lake, & Co., Patent Agents,
Southampton Buildings, London. "AN IMPROVED PROCESS OF REFINING IMPURE
LEAD, AND SEPARATING THEREFROM GOLD, SILVER, AND OTHER METALS." A.
communication from abroad by Nathaniel Shepard Keith, of Brooklyn, New York,
United States of America, Chemist and Electrician.
This Invention relates to an improved process of refining impure lead, and sepa-
rating or removing therefrom gold, silver, and other metals.
The said Invention consists, primarily, in subjecting such lead to the process of
wherein
electrolysis, that is to say, to the action of solvents excited by electricity,
the impure lead is resolved into its elementary constituents, the impurities are left
undissolved, and the lead is at the same time separated and deposited by itself in a'
purified form.
The said Invention embraces,-
The exposing of the lead to be dissolved to the action of an electric current under
the conditions of an anode in a suitable electrolyzing solution or bath.
Also, the use of such bath or solution for refining impure lead, aided by the action
of heat applied to the solution.
Also, the combination of a series of two or more baths with the same battery or

page_text: generator, and with each other, by electrically connecting the cathode of the first
bath of the series with the anode of the second bath, and the cathodo of the second
with the anode of the third, and so on.
Also, a bath composed of an acidulated solution of a salt of lead, for the purposes
herein-after set forth.
Also, the double operation of separating the impurities from the lead, rendering
them easy of refinement, and at the same time obtaining metallic lead in a purc
state.
In carrying this Invention into practice I use a competent generator of electricity
in connection with a suitable bath composed of an electrolyzing solution, into which
I introduce the lead to be treated as the positive pole of the battery, and any metallic
or other electric conductor as the cathode or negative pole.
For the bath I use solutions of some of the salts of lead; but in the action of
normal solutions of the neutral salts of lead, sub-salts and oxides form upon the elec-
trodes and in the solutions, thus decomposing the solutions and stopping the
electrolytic action by reason of the non-conducting coating on the electrodes, and
the changed character of the solutions, in consequence of which the electrolytic
action gradually grows less, and often ceases altogether, and at best it is imperfectly
carried on in normal solutions. To overcome these difficulties I use solutious of
acetate of lead, of chloride of lead, or of nitrate of lead, each made acid either by
acetic or hydrochloric acid, having ascertained by practical experience that this
acidulation of the said solutions prevents such formation of sub-salts and oxides
upon the electrodes, whereby the electrolytic action remains unimpaired an indefinite
length of time.
It is necessary to use solutions of salts of lead, which, under the exciting influence
of electricity as applied in the electrolytic bath, do not dissolvo gold, silver, and
other constituents of commercial impure lead, pig lead, or of lead known in tho
market by the name of "base bullion," but will dissolve such lead. I therefore
employ the afore-named solution or solutions of acetate, or chloride, or nitrate of
load made acid, as described, having found that these readily dissolve the lead when
electrolytically treated, but do not dissolve the gold, silver, and other metals.
I have used various solutions, notably those of oxide of lead, in solutions of caustic
soda. One of the best I have tried is a solution of acetate of lead made acid by
acetic acid.
A very good solution consists of sulphate of lead dissolved in solutions of the
various acetates and chlorides of the alkaline metals, such as sodium, ammonium,
potassium, and the like; this solution can be used acid, neutral, or alkaline, and
does not form insoluble salts.
Sulphate of lead has not been used before in the electrolysis of lead for any
purpose.
I use the solutions of the alkaline metals in which to dissolve the sulphate of lead
because they dissolve the sulphates readily, and also form good conductors for the
electric current.
I also prefer nearly saturated solutions, though almost any strength of solution
may be used.
Having prepared my bath by placing the solution in a proper vessel, I attach
some of the before-mentioned impure lead, preferably previously cast or rolled into
sheets, to the positive pole of a generator of clectricity, and immerse it in the bath,
thus making it an anode. To the negative pole I attach a sheet or sheets of copper,
brass, lead, or other metal or carbon immersed in the bath, thus making it or them
the cathode. I procure the necessary current of electricity from any source, but
preferably from magneto-electric or dynamo-electric machines, in well-known ways.
As long as a current of electricity flows in this circuit, lead is dissolved from the
anode, and deposited in a pure crystalline metallic form on the cathode, from which
it may be removed for melting into commercial shape, or otherwise utilized. Such 5

page_text: gold, silver, antimony, copper, tin, and the like as may be in the anode remain
undissolved, and gradually drop off the surface of the anode in the shape of a fine
powder into properly placed receptacles, whence the powder may be removed for
subsequent refining, or molting, or sale; or the anode may be placed in a bag of
muslin or like material, which will retain the undissolved impurities, so that they
may be readily removod.
I increase the size and number of the electrolyzing baths to accord with the
necessary extent of the operation; and where a series of two or more baths for
electrolyzing lead are used, I arrange them so that the cathode of the first bath of
the series is electrically connected with the anode of a second bath, and the cathode
of the second bath is electrically connected with the anode of a third bath, and so
on through any number; this is a valuable plan, for I have found that though the
resistance thus added to the electric current decreases the current passing, and the
amount of lead dissolved and deposited in any of the series, yet the aggregate
amount of lead dissolved and deposited is increased with a corresponding decrease
in the aggregate consumption of zinc and acid in the galvanic battery connected
therewith, or if an electrical machine be used, a corresponding decrease in the power
used to drive it. In this manner I make a great saving in the expense of the elec-
tricity needed for electrolyzing a large amount of lead. I have also found that by
heating the solutions I use for electrolyzing lead their conductivity is much
increased, so that electric batteries or machines of much less electro-motive force
may be used, thus increasing the economy of this process.
As I prevent the formation of sub-salts and oxides on the electrodes and in the
solutions, I get the full electrical equivalent of lead dissolved and deposited for the
electricity used, and the solutions are not decomposed.
Having thus fully described the said Invention as communicated to me by my
foreign correspondent, and the manner of performing the same, I wish it understood
that I am aware of lead for experimental purposes having been deposited from
solutions of its salts, such as the nitrate and acetate, and from solutions of oxide of
lead in caustic soda or caustic potash liquors, but this deposit has never been accom-
plished, even experimentally, excepting with normal solutions of the neutral salts,
and the electrolysis of lead has not been of any practical utility prior to this Inven-
tion, and I therefore claim,―
First. The process of refining impure lead by electrolysis, consisting in subjecting
the lead to the action of a suitable electrolytic bath in connection with the positive
pole of the battery, whereby the lead to be treated becomes the anode in the said
process and is dissolved, and its constituents separated therefrom, as above
described.
Second. In the process of refining impure lead by electrolysis, subjecting the lead
under the conditions of an anode to the action of an electrolytic solution aided by
the influence of artificial heat applied to the solution.
Third. In the process of refining lead by electrolysis, the combination of two or
more baths with the same battery and with each other by connecting the cathode
of the first bath with the anode of the second bath, and the cathode of the second
bath with the anode of the third, and so on.
Fourth. In the process of refining lead by electrolysis, the electrolytic bath com-
posed of a salt of lead adapted to prevent the formation of oxide and sub-salts, and
maintain the electrolytic action unimpaired, as above described.
Fifth. In the process of purifying lead by electrolysis, the herein described elec-
trolyzing solutions composed of solutions either of acetate, or chloride, or nitrate of
lead, or mixtures of the same made acid by means of acetic or hydrochloric acid.
Sixth. The herein described process of separating gold, silver, and other metals
from lead, rendering them easy of refinement, while at the same time obtaining
metallic lead in a pure state suitable for manufacturing purposes by means of elec-
tricity, which process consists in the employment of acid solutions of lead salts in
the bath with an anode of impure lead, as specified.

page_text: Seventh. The electrolytic baths consisting of solutions of sulphate of lead, as and
for the purposes specified.
In witness whereof, I, the said William Robert Lake, have hereunto set my
hand and seal, this Twentieth day of November, in the year of our Lord
One thousand eight hundred and seventy-eight.
WM ROBT LAKE. (L.S.)