IMPROVEMENTS IN THE MANURACTURE OR WHITE LEAD
Year: 1858

page_text: LETTERS PATENT to Peter Brown and Benjamin Young, of Spa Road;
Bermondsey, in the Borough of Southwark, Glue Manufacturers, for
the Invention of "IMPROVEMENTS IN THE MANURACTURE OR WHITE LEAD"
Sealed the 21st December 1858, and dated the 22nd June 1858.
PROVISIONAL SPECIFICATION left by the said Peter Brown and Ben-
jamin Young at the Office of the Commissioners of Patents, with their
Petition, on the 22nd June 1858.
We, PETER BROWN and BENJAMIN YOUNG, of Spa Road, Bermondsey, in
the Borough of Southwark, Glue Manufacturers, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF WHITE LEAD,"
to be as follows:-
The principal object of our Invention of improvements in the manufacture
of white lead is to shorten the process whereby this article is now produced.
To this end we prepare a nitrate lead by some suitable process,, as is well
known to chemists. The particular process to be employed for producing the
nitrate must depend upon circumstances, such as whether the lead is in a
pure metallic state, or in the form of litharge, or combined with any chemical
element or ingredient. The nitrate of lead, in the form of a solution, is then
placed in a suitable vessel, and carbonic acid, obtained by preference from
the calcination of chalk or carbonate of lime, or by the chemical decomposition
of any other cheap and suitable carbonate, is passed through the solution until

page_text: the nitrate of lead solution is saturated with carbonic acid. To this saturated
solution we then add a caustic alkali, say, caustic soda, which immediately
combines with a portion of the nitric acid that was before in combination
with the lead. The oxide of lead thus produced combines in its turn with
the carbonic acid in the solution, and becomes converted into a carbonate of
lead, which being insoluble immediately precipitates, and falls to the bottom.
These decomposing operations are continued until all the nitrate is converted
into carbonate of lead, which is then removed from the vessel, and well washed
in lime water, whereby all the free acid is taken up. The supernatant liquid is
then drawn off, and the precipitate, when dried, either naturally or artificially,
is ready for the market.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Peter Brown and Benjamin Young in the Great Seal Patent
Office, on the 22nd December 1858.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, PETER
BROWN and BENJAMIN YOUNG, of Spa Road, Bermondsey, in the Borough of
Southwark, Glue Manufacturers, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of June, in the year of our
Lord One thousand eight hundred and fifty-eight, in the twenty-second year
of Her reign, did, for Herself, Her heirs and successors, give and grant unto
us, the said Peter Brown and Benjamin Young, Her special license that we,
the said Peter Brown and Benjamin Young, our executors, administrators,
and assigns, or such others as we, the said Peter Brown and Benjamin
Young, our 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 we,
the said Peter Brown and Benjamin Young, by an instrument in writing
under our hands and seals, or under the hand and seal of one of us, should
particularly 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 imme-
diately after the date of the said Letters Patent.

page_text: NOW KNOW YE, that I, the said Benjamin Young, on behalf of myself
and of the said Peter Brown, do hereby declare the nature of our said
Invention, and in what manner the same is to be performed, to be par-
ticularly described and ascertained in and by the following statement (that
is to say):
This Invention relates to an improved mode of obtaining the pigment com-
monly known as white lead, the object being to shorten the process, and
consequently to effect a material economy in the manufacture. To this end
we first prepare a nitrate of lead by any suitable process well known to
chemists. The selection of the process to be employed for producing the
nitrate must depend upon circumstances, such as whether the lead is in a
pure metallic state, or in the form of litharge, or combined with any chemical
element or ingredient. We prefer, however, the use of litharge, as in that
state the metal may be readily attacked by the diluted nitric acid employed to
dissolve it, and reduced to nitrate of lead. The nitrate of lead, however
obtained, is while in the form of a solution placed in a suitable vessel, and
submitted to the action of streams of carbonic acid gas, obtained by pre-
ference from the calcination of chalk or carbonate of lime in a closed vessel
or retort, or the carbonic acid gas may be generated by the chemical decom-
position of any other cheap and suitable carbonate. The carbonic acid gas is
passed into the vessel containing the nitrate of lead solution until the solution
has become saturated with carbonic acid, a coil of pierced pipe or suitable and
well-known arrangement being employed for effecting the distribution of the
acid through the liquor. To this saturated solution we next add an excess of
caustic alkali, say caustic soda, which immediately enters into combination
with a portion of the nitric acid that was before combined with the lead, and
forms nitrate of scda. The metal thus liberated combines in its turn with the
carbonic acid in the solution, and becomes converted into a carbonate of lead,
which, being insoluble, immediately precipitates and falls to the bottom. The
chemical action thus set up is continued until all the nitrate has been con-
verted into carbonate of lead. The supernatant liquor is then run off from
the vessel, and the carbonate of lead is subjected to lixiviation in a strong
solution of lime, assisted by the action of a stirrer, by which means all the
free acid remaining in the carbonate will be taken up or neutralized. After
the carbonate of lead has been allowed to settle, the lime water is then
drawn off. The precipitate, which is the pure white lead of commerce, is
next to be removed from the vessel, and dried, either by natural or artificial
means, after which it will be ready for the market.
Having now set forth the nature of our Invention of "Improvements in

page_text: the Manufacture of White Lead," and explained the manner of carrying the
same into effect, we wish it to be understood that we do not claim the pre-
paration of nitrate of lead from metallic lead or litharge, or any other of its
compounds, for the conversion of the same into white lead; but what we
claim under the above in part recited Letters Patent is the treatment of
nitrate of lead, however obtained, in the manner and for the purpose above
described.
In witness whereof, I, the said Benjamin Young, have hereunto set my
hand and seal, the Twenty-second day of December, in the year of
our Lord One thousand eight hundred and fifty-eight.
Witness,
J. W. MOFFATT,
66, Chancery Lane.
BENJAMIN YOUNG. (L.S.)