IMPROVEMENTS IN THE MANUFACTURE OF WHITE AND RED LEAD AND LITHARGE
Year: 1874

page_text: LETTERS PATENT to William Baker, of Sheffield, in the County of
York, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF
WHITE AND RED LEAD AND LITHARGE."
Sealed the 26th June 1874, and dated the 28th April 1874.
PROVISIONAL SPECIFICATION left by the said William Baker at the
Office of the Commissioners of Patents, with his Petition, on the
28th April 1874.
I, WILLIAM BAKER, of Sheffield, in the County of York, do hereby
declare the nature of my said Invention for "IMPROVEMENTS IN
MANUFACTURE OF WHITE AND RED LEAD AND LITHARGE," to be as follows:-
--
THE
My Invention for improvements in the manufacture of white lead
and of red lead and litharge consists in the employment of lead alloyed.
with a certain amount of zinc, such lead to be used for the making of
red lead litharge or cast for corrosion in the usual manner for its
exposure to the action of carbonic acid, aqueous vapor, and acetic acid,
according to the usual methods of making white lead.

page_text: For the purpose of carrying out my Invention I take lead which
if necessary has been refined by any of the well-known 'oxidation
processes to remove sulphur, antimony, and arsenic, and afterwards
desilverized either by means of zinc (Parkes' process), or by repeated
crystallizations (Pattenson's process).
In the case of lead which has been desilverized by zinc there will be
aboutto per cent. of zinc left in the lead, and if the silver has been
reduced to about ½ oz. per ton, I find such lead containing as it does
the above proportion of zinc, is eminently fitted either for corrosion to
produce the carbonate of lead or white lead of commerce, or for
oxidation to produce litharge or red lead.
In the case of lead which has not been desilverized by zinc, I ascertain
that the silver is sufficiently reduced, as a very small proportion of
silver imparts a red țint to white lead corrosions. I then add per
cent. of zinc or thereabout before casting into the forms used for
corrosion.
I wish it to be understood that I do not confine myself to the exact
proportion of per cent. of zinc, as a little more or less does not affect
the result; but with this proportion of zinc alloyed with lead which
has been previously purified from other elements, I find excellent
corrosions are obtained, and that the process of oxidation for litharge
and red lead is much facilitated.
By this Invention the cost of removing the zinc from lead which has
been desilverized with this metal is saved when such lead is used for
making white lead or red lead or litharge.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Baker in the Great Seal Patent Office on
the 24th October 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
BAKER, of Sheffield, in the County of York, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-eighth day of April, in the
year of our Lord. One thousand eight hundred and seventy-four, in

page_text: the thirty-seventh year of Her reign, did, for Herself, Her heirs and
successors, give and grant unto me, the said William Baker, Her
special license that I, the said William Baker, my executors, adminis-
trators, and assigns, or such others as I, the said William Baker, my
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 Kingdom of Great Britain and
Ireland, the Channel Islands, and Isle of Man, an Invention for "Im-
PROVEMENTS IN THE MANUFACTURE OF WHITE AND RED LEAD AND LITHARGE,"
upon the condition (amongst others) that I, the said William Baker,
my executors or administrators, by an instrument in writing under my
hand and seal, 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 immediately after the date of the saiḍ
Letters Patent.
NOW KNOW YE, that I, the said William Baker, 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 Invention for improvements in the manufacture of white lead
and of red lead and litharge, consists in the employment of lead alloyed
with a certain amount of zinc, such lead to be used for the making
of red lead litharge, or cast for corrosion in the usual manner for its
exposure to the action of carbonic acid, aqueous vapour, and acetic acid,
according to the usual methods of making white lead.
For the purpose of carrying out my Invention I take lead which
if necessary has been refined by any of the well-known oxidation
processes to remove sulphur, antimony, and arsenic, and afterwards
desilverized either by means of zinc (Parkes' process), or by repeated
crystallizations (Pattinson's process.
In the case of lead which has been desilverized by zinc there will be
aboutto per cent. of zinc left in the lead, and if the silver has been
reduced to about ½ oz. per ton, I find such lead containing as it does
the above proportion of zinc, is eminently fitted either for corrosion to

page_text: produce the carbonate of lead or white lead of commerce, or for
'oxidation to produce litharge or red lead.
In the case of lead which has not been desilverized by zinc I ascertain
that the silver is sufficiently reduced, as a very small proportion of
silver imparts a red tint to white lead corrosions. I then add per
cent. of zinc, or thereabout, before casting into the forms used for
corrosion.
I wish it to be understood that I do not confine myself to the exact
proportion of per cent. of zinc, as a little more or less does not affect
the result; but with this proportion of zinc alloyed with lead which
has been previously purified from other elements I find excellent
corrosions are obtained, and that the process of oxidation for litharge
and red lead is much facilitated.
+
By this Invention the cost of removing the zinc from lead which has
been desilverized with this metal is saved when such lead is used for 1
making white lead or red lead or litharge.
Having now described and particularly ascertained the nature of my
said Invention, and the manner in which the same is or may be used or
carried into effect, I would observe in conclusion that what I consider to be
novel and original, and therefore claim as the Invention secured to me by 2
the herein-before in part recited Letters Patent is, the addition of a
certain proportion of zinc to lead when it is intended to employ the
same for the manufacture of white lead, substantially as herein-before
described.
In witness whereof T the said William Rakor have to this