IMPROVEMENTS IN THE MANUFACTURE OF A PIGMENT
Year: 1876

page_text: LETTERS PATENT to William Whitthread, of 34, Moorfields, Liverpool, Analyst,
for the Invention of "IMPROVEMENTS IN THE MANUFACTURE OF A PIGMENT."
PROVISIONAL SPECIFICATION left by the said William Whitthread at the
Office of the Commissioners of Patents on the 8th June 1876.
WILLIAM WHITTHREAD, of 34, Moorfields, Liverpool, Analyst.
IN THE MANUFACTURE OF A PIGMENT."
"IMPROVEMENTS
This Invention consists of a new mode of preparing compounds of which zinc
constitutes the basis, and which may be used for purposes for which white lead is
now used.
I tako neutral solutions of the salts of zinc, preferring the sulphato or chloride
because cheapest, or alkaline solutions of oxide of zinc, or alkaline solutions of the
hydrated oxide of zinc, or solutions prepared by adding an excess of an alkali to
solutions of salts of zinc, whereby the precipitate first produced is redissolved; or
any of the above solutions, or a mixture of any of these solutions, and I pass
sulphide of hydrogen (hydrogen monosulphide) through the solution or solutions
above named. A white precipitate of the hydrated sulphide of zinc will be pro-
duced, which I collect, wash, dry, and heat to dull redness, and allow to cool. The
pigment is then fit for use.
When a neutral salt of zinc, as the sulphate, for instance, bas been used, only a
portion of the zinc will be removed from the solution by the sulphide of hydrogen,
and an equivalent quantity of acid will be set free. To obtain the whole of the
zinc contained in the solution I neutralized the free acid and repeat the precipi-
tation with the sulphide of hydrogen; and this I again do as often as is needful.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said William Whitthread in the Great Seal Patent Office on the 1st
December 1876.
WILLIAM WHITTHREAD, of 34, Moorfields, Liverpool, Analyst.
IN THE MANUFACTURE OF A PIGMENT."
"IMPROVEMENTS
This Invention consists of a new mode of preparing compounds of which zinc
constitutes the basis, and which may be used for purposes for which white lead is
now used.

page_text: I take neutral solutions of the salts of zinc, preferring the sulphate or chloride
because cheapest, or alkaline solutions of oxido of zinc, or alkaline solutions of
the hydrated oxide of zinc, or solutions prepared by adding an excess of an alkali
to solutions of salts of zinc, whereby the precipitate first produced is redissolved;
or any of the above solutions or a mixture of any of these solutions, and I pass
sulphide of hydrogen (hydrogen monosulphide) through the solution or solutions
above named. A white precipitate of the hydrated sulphide of zinc will be pro-
duced, which I collect, wash, dry, and heat to a dull redness, and allow to cool.
The pigment is then fit for use.
When a neutral salt of zinc, as the sulphate, for instance, has been used, only a
portion of the zinc will be removed from solution by the sulphide of hydrogen, and
an equivalent quantity of acid will be set free. To obtain the whole of the zinc
contained in the solution I neutralize the free acid and repeat the precipitation
with the sulphide of hydrogen, and this I again do as often as is needful.
Having now described my Invention, "Improvements in the Manufacture of a
Pigment," I wish it to be understood that what I claim as my Invention is-
Firstly. The improvements in the manufacture of a pigment, as set forth in the
herein in part recited Letters Patent.
Secondly. The materials and novel treatment thereof, as herein set forth, for the
purpose of producing a pigment.
And, thirdly. The mode or method herein described and set forth of preparing a
pigment which may be used or employed as a substitute for white lead as a
pigment.
In witness whereof, I, the said William Whitthread, have hereunto set my
hand and seal, this Twenty-eighth day of November, One thousand eight
hundred and seventy-six.
Witness,
W. H. SMITH,
Patent Agent,
3, York Buildings,
Dale St.,
Liverpool.
WILLIAM WHITTHREAD. (L.S.)