IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD
Year: 1874

page_text: LETTERS PATENT to Bernard Charles Molloy, of the Temple, Barrister-
at-Law, and Desmond Gerald Fitzgerald, of Brixton, in the County
of Middlesex, Electrician, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF WHITE LEAD."
PROVISIONAL SPECIFICATION left by the said Bernard Charles Molloy
and Desmond Gerald Fitzgerald at the Office of the Commissioners
of Patents, with their Petition, on the 21st January 1874.
We, BERNARD CHARLES MOLLOY, of the Temple, Barrister-at-Law,
and DESMOND GERALD FITZGERALD, of Brixton, in the County of
Middlesex, Electrician, do hereby declare the nature of our said Invention
for "IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD," to be as
follows:-

page_text: Secondly. In effecting the decomposition of chloride of lead, together
with oxide of lead, such for example as oxychloride of lead, by means of
the earthy carbonates, such for example as the carbonates of lime or
baryta.
Thirdly. In effecting the decomposition of the before-mentioned
chlorides of lead by means of a mixture of an earthy carbonate, together
with an alkaline earth or the hydrate of the same.
Fourthly. By submitting litharge or oxide of lead to the action of
hydrochloric acid, and then to the action of an earthy carbonate, such
latter decomposition being effected by preference in a closed vessel.
The decomposition of the before-mentioned chlorides of lead by means
of the carthy carbonates, or by means of a mixture of the earthy car-
bonates, together with an alkaline carth or carths, or the hydrates of the
same, having been effected by bringing into contact the same by preference
when in a fine state of division, and suspended in water, the solution
after such decomposition will contain the chloride of the earth employed,
which we treat as follows:-From the solution of the earth which is thus
obtained we regenerate the earthy carbonate in a state of purity by
means of a solution of carbonate of ammonia. The chloride of ammonium
thus formed may in its turn be reconverted into carbonate of ammonia
by distillation from an earthy carbonate, which for this purpose may be
in a crude or impure condition.
One method by which we obtain carbonate of lime suitable for the
before-mentioned purposes is by the action upon solutions of caustic lime
of carbonic acid generated by combustion or otherwise, the lime being
continuously dissolved and separated from its impurities by the circula-
tion of the solvent, from which it is precipitated as carbonate.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent
filed by the said Bernard Charles Molloy and Desmond Gerald
Fitzgerald in the Great Seal Patent Office on the 21st July 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, wc, BERNARD
CHARLES MOLLOY, of the Temple, Barrister-at-Law, and DESMOND
GERALD FITZ-GERALD, of Brixton, in the County of Middlesex,
Electrician, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-first day of January, in the
year of our Lord One thousand eight hundred and seventy-four, in
the 37th year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said Bernard Charles Molloy and Desmond
Gerald Fitz-Gerald, Her special license that we, the said Bernard Charles
Molloy and Desmond Gerald Fitz-Gerald, our executors, administrators,
and assigns, or such others as we, the said Bernard Charles Molloy and
Desmond Gerald Fitz-Gerald, our executors, administrators, or 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 King-
dom 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 we, the said Bernard Charles
Molloy and Desmond Gerald Fitz-Gerald, our executors or administrators,
by an instrument in writing under our hands and seals, should par-
ticularly describe and ascertain the nature of the said Invention, 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 we, the said Bernard Charles Molloy and
Desmond Gerald Fitz-Gerald, do hereby declare the nature of our said
Invention, and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following state-
ment, reference being had to the accompanying Drawings, and to the
letters and figures marked thereon, that is to say :-
This Invention relates to the production of what is known as white
1

page_text: First. In effecting the decomposition of chloride of lead by means
of the carthy carbonates, such for example as the carbonate of lime or
of baryta.
Secondly. In effecting the decomposition of chloride of lead, together
with oxide of lead, such for example as oxychloride of lead, by means of 5
the earthy carbonates, such for example as the carbonates of lime or
baryta.
Thirdly. In effecting the decomposition of the before-mentioned chloride
of lead by means of a mixture of an earthy carbonate, together with an
alkaline earth, or the hydrate of the same.
Fourthly. By submitting litharge or oxide of lead to the action of
hydrochloric acid and an carthy carbonate, such latter decomposition
being effected by preference in a closed vessel.
1
In carrying our Invention into effect by the process first referred to
we mix an equivalent of chloride of lead and an equivalent of carbonate 1
of lime (purified chalk) in fine powder with sufficient water to form a
magma, and heat the mixture in order to hasten the reaction shown
in the following equation:—

page_text: we obtain a white lead possessing strong drying properties (by reason of
the excess of hydrated oxide) according to the following reaction :-
Or in the case or an oxyenioride naving the composton D Vig
(PbO), H, O (as obtained by boiling litharge with an alkaline chloride)
we obtain a white lead containing great excess of "driers" by treating
an equivalent of the oxychloride with one of baric or calcic carbonate;
thus-
-
If however it be desired to obtain the ordinary basic carbonate (white
lead) from this oxychloride we add to it hydrochloric acid before treating
with the earthy carbonate, the proportions being indicated by the fol-
lowing equation :-
-

page_text: of stoneware, slate, stone, or other suitable material. This reaction is
indicated by the following equation ::
.
3 PbO4 H Cl + 2 Ca CO₂ =
3
2 Pb C O,, Pb H₂ O₂ + 2 Ca Cl, † H, O.
In carrying this process into effect the litharge and carthy carbonate
may first be intimately mixed, and the hydrochloric acid then added
gradually (by means of a pipe with double stop-cock or otherwise); or
the acid and litharge may first be mixed, and the earthy carbonate sub-
sequently added; the mixture being stirred or agitated by suitable
appliances, as is well understood.
From the solutions of the carthy chlorides obtained in the above-
mentioned reactions we regenerate the earthy carbonato in a state of
purity by means of a solution of the normal carbonate of ammonia, as
shewn in the following equation :-
1
3 Ca CO, +6 NH, Cl.
The chloride of ammonium thus obtained may in its turn be reconverted
into the mixture of susquicarbonate of ammonia with caustic ammonia,
which constitutes (or is equivalent to) the normal carbonate of ammonia 2
by distillation from common chalk; thus:-
-
6 NH, Cl + 3 Ca CO₂ =
2 (N E,), O, 3 CO+2NH + H, O.
We also in some cases obtain pure carbonate of lime by the action
upon solutions of caustic lime of carbonic acid generated by combustion 2
or otherwise, the lime being continuously dissolved and separated from
its impurities by the circulation of the solvent from which it is preci-
pitated as carbonate.
Having now described and particularly ascertained the nature of our
said Invention, and the manner in which the same is or may be used or 3
carried into effect, we would observe in conclusion that what we consider
to be novel and original and therefore claim as the Invention secured
to us by the herein-before in part recited Letters Patent is,―
First. Effecting the decomposition of chloride of lead by means of an
earthy carbonate, so as to obtain carbonate of lead, as herein-before 3.
described,

page_text: Second. Effecting the decomposition of what is known as oxychloride
of lead, or of a mixture of chloride of lead with oxide or oxychloride of
lead, by means of an carthy carbonate, so as to obtain white lead, or
white lead in admixture with excess of hydrated oxide of lead, as herein-
before described.
Third. Effecting the decomposition of chloride of lead by means of an
earthy carbonate in conjunction with an alkaline earth or its hydrate, so
as to obtain what is known as white lead.
Fourth. Producing white lead by the reaction upon each other of
litharge, an carthy carbonate, and hydrochloric acid in admixture within
a close vessel, as herein-before described.
In witness whereof, I, the said Desmond Gerald Fitz-Gerald, on
behalf of myself and the said Bernard Charles Molloy, have to
this our Specification set my hand and seal, this Twentieth day
of July One thousand eight hundred and seventy-four.
DESMOND G. FITZ-GERALD. (L.S.)