IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD
Year: 1865

page_text: LETTERS PATENT to Peter Spence, of Newton Heath, in the County of
Lancaster, Manufacturing Chemist, for the Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF WHITE LEAD."
Sealed the 18th March 1866, and dated the 22nd September 1865.
PROVISIONAL SPECIFICATION left by the said Peter Spence at the
Office of the Commissioners of Patents, with his Petition, on the 22nd
September 1865.
I, PETER SPENCE, of Newton Heath, Manchester, in the County of Lan-.
caster, Manufacturing Chemist, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD," to be as
follows:-
My Invention consists in the production of white lead by dissolving salts of
lead in solutions of an alkali, and then precipitating the required carbonate.
In order to illustrate how my Invention may he carried into effect I will sup-
pose it desired to produce white lead from galena. This substance I calcine
in a suitable furnace, and thus convert it, or partly so, into oxide; some sul-
phate, however, will be present, which I treat with carbonate of soda, and the
whole is then submitted to the action of caustic soda until dissolved, after
which it is converted into carbonate of lead by blowing carbonic acid gas

page_text: through it, or by other suitable ordinary treatment. In like manner I dissolve
other salts of lead in solutions of alkalis, so as to prepare them for being
precipitated as white lead. Native carbonates will of course merely require
SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Peter Spence in the Great Seal Patent Office on the 21st
March 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PETER
SPENCE, of Newton Heath, in the County of Lancaster, Manufacturing
Chemist, send greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of September, in the year of our
Lord One thousand eight hundred and sixty-five, in the twenty-ninth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Peter Spence, Her special license that I, the said Peter Spence,
my executors, administrators, and assigns, or such others as I, the said Peter
Spence, my executors, administrators, and assigns, should at any time
agree with, and no others, from time to time and at all times thereafter
during the term therein expressed, should and lawfully might make, use,
exercise, and vend, within the United Kingdom of Great Britain and Ireland,
the Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF 'WHITE LEAD,'" upon the condition, amongst others, that
I, the said Peter Spence, by an instrument in writing under my hand and
seal, should particularly describe and ascertain the nature of the said Inven-
tion, and in what manner the same was to be performed, and cause the same
to be filed in the Great Seal Patent Office within six calendar months next
and immediately after the date of the said Letters Patent.
"
NOW KNOW YE, that I, the said Peter Spence, do hereby declare the
nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement, that is to say :-
My improvement consists in dissolving oxide or carbonate of lead by the
use of caustic alkaline solutions, and for this purpose I prefer caustic soda,
but certain other caustic solutions will answer the purpose. I take the afore-
said-oxide for carbonate of lead, or substances containing them, and reduce them
to powder and stir the said powder of oxide or carbonate of lead, or substance

page_text: containing oxide or carbonate of lead, in the solution of caustic soda, and I
find it is not needful that the said solution should be hot, and after stirring till
the solution will dissolve no more, I remove the solution and add more until I
find that all the oxide or carbonate of lead in the said substances is dissolved:
I
may state that any ore that can by calcination or otherwise be brought into
the state of oxide or carbonate of lead, or "to contain any considerable portion
of oxide or carbonate of lead, although containing other substances, is fit for
my purpose. Galena or substances containing galena I calcine at a low heat,
either in the ordinary reverberatory furnace or other suitable furnace. I heat
these ores or substances till the galena is completely calcined, but avoiding its
reduction into metallic lead. I now find that the galena has been partly
converted into oxide of lead and partly into sulphate of lead; before stirring
this into the caustic solution I subject it to the action of a solution of soda
ash; but if the calcined galena or ore containing galena should also contain
any oxide of copper or a large portion of oxide of zinc, I prefer in that case
to use a solution of ammonia or carbonate of ammonia, and I find that such
solution not only removes the sulphuric acid from the sulphate of lead, but
also removes the oxide of copper and zinc, which might, if left in the: ore, be
dissolved or partially dissolved by the solution of caustic of soda. These
solutions of ammonia, or carbonate of ammonia, or carbonate of soda do not
dissolve the oxide of lead, but merely remove the sulphuric acid from the
sulphate of lead. If the ores or matters only contain a small portion of zinc
oxide, and if the solution of that by the caustic soda and its precipitation
along with the carbonate of lead is not found to be detrimental, then I prefer
using the solution of carbonate of soda for removal of the sulphuric acid.
The soda ash or ammoniacal solution being removed and washed out by water,
the material containing the calcined. galena is now fit for being stirred in the
solution of caustic soda.
Having now obtained from any of these ores or substances containing
oxide or carbonate of lead by stirring, as aforesaid, a liquid holding oxide of
lead in solution,. I allow it to settle till perfectly clear, and then remove the
clear solution. into a vessel or vessels into which I can conveniently throw by
pipes pierced with numerous holes a continuous stream of carbonic acid gas..
The said carbonic acid gas combines both with the soda and the lead oxide,
and as soon as the soda becomes carbonated it parts with the lead oxide, which
is now precipitated as a pure white substance, partly oxide and partly car-
bonate of lead, commonly called "white lead." As soon as by observation.or
trial it is seen that no more parcipitate is forming, the supply of carbonic acid
gas is stopped and the white lead is allowed to settle. The solution has now

page_text: become carbonate, of, soda;, and is, removed, and after being subjected to the
action of caustic lime, as is well known, and so, converted into caustic soda
solution, it is ready again for acting on the substances as aforesaid, containing
oxide or carbonate of lead. For the precipitation of the said oxide of lead I
may say that the carbonic acid gas I use, may be obtained either from the
action of hydrochloric acid on limestone or other carbonate of lime, or may be
procured by the combustion of coke, or charcoal, or in any other convenient
manner, it being needful, however, that no sulphurated hydrogen should be in
the carbonic acid used; carbonate of ammonia, or bi-carbonate of soda, or
other soluble carbonates or bi-carbonates might be used for precipitating the
white lead, but I prefer carbonic acid gas as more economical. The soda ash
solution used with calcined galena will have to be replaced after a time, as it
becomes.converted into sulphate of soda. The ammoniacal solutions may be
freed from 'copper and zinc by well-known methods. The caustic soda
solution can be used over and over again, only requiring to be causticised with
quicklime after precipitation and before being again used for dissolving the
oxide of lead. The precipitated white lead requires to be well washed with
pure water and dried before being fit for sale.
Having thus described the nature of my said Invention and the manner in
which the same is to be performed, I desire it to be understood that I claim
as secured to me: under the above in part, recited Letters Patent, the pro-
duction of "white lead," by treating substances containing oxide or
carbonate, of lead with caustic alkaline solutions, and then precipitating the
required white; lead."
In witness whereof, I, the said Peter Spence, have hereunto set my hand
..and seal, this Twentieth day of March, in the year of our Lord One
thousand eight hundred and sixty-six.
D SPENCE
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