Year: 1885

page_text: I JOSEPH BENJAMIN FREEMAN of White Hart Lane, Tottenham, in the county
of Middlesex, Varnish and Colour Manufacturer do hereby declare the nature of
this Invention to be as follows:-
My Invention relates to an improvement in the white pigment for which
I obtained previous Letters Patent dated October 13th 1882 No 4879; and consists
in the addition to the mixture of lead sulphate and zinc white (zinc oxide or sulphide)
of a suitable proportion of barium sulphate; the whole being incorporated by
pressure and friction produced by grinding under edge runners or otherwise,
this grinding producing, as before, a remarkable change in the character
mixture.
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By the addition of the barium sulphate I obtain a pigment of even still greater.
density, body, and opacity, than with the lead and zinc only, and possessing a
considerably greater amount of freedom in working.
I now prefer to produce the lead sulphate direct from metallic lead by submitting
feathers, or small flakes of metallic lead to the alternate action of dilute acetic acid,
and of atmospheric air, thereby forming a solution of lead acetate to which I add
sulphuric acid to precipitate the lead as sulphate.

page_text: I JOSEPH BENJAMIN FREEMAN of White Hart Lane Tottenham in the County of
Middlesex, Varnish and Color Manufacturer, do hereby declare the nature of this
invention and in what manner the same is to be performed, to be particularly
described and ascertained in and by the following statement:-
This Invention relates to improvements in the white pigment, for which former
Letters Patent were granted to me, dated October 13th 1882, and numbered 4879.
The present Invention consists in the manufacture of an improved white
pigment, which, when ground with Oil in the customary way, forms a paint equal
in body, opacity, or covering property, to the best white-lead produced by the Dutch
method, and superior to it in color, durability, and density. The pigment moreover,
possesses little or no smell, and is innoxious or non-poisonous.
This improved white pigment is produced by the incorporation, or combination,
by grinding together in the manner hereafter described, of lead sulphate, "zinc-
white," and barium sulphate. These materials are mixed together in suitable
proportions, and submitted to great pressure and friction by grinding the mixture
(preferably when in a dry state) under ordinary edge-runners, or otherwise.
Under the term "zinc white" I would have it understood that I include either
zinc oxide or zinc sulphide, or a mixture of the two in any proportions, as both
these substances are designated "zinc white" in commerce.
By grinding "zinc white" and lead sulphate together in the manner described,
the particles of the lead and zinc compounds become incorporated together in a
remarkable manner, an entire change being produced in their character, and by the
addition to the lead and zinc compounds of the barium sulphate the change of
character above referred to is very greatly intensified, a pigment of equal, if not of
even greater density, body, and opacity, than with the lead and zinc compounds
only, being produced.
It might be supposed, at first sight, having regard to the relative prices of the
three ingredients that the barium sulphate is employed by me rather as a diluent
or adulterant than for the purpose of imparting any definite qualities to the
pigment, but such is not the case. The incorporation in the manner herein
described of the barium sulphate with the lead and zinc compounds has, besides
the effect of enhancing the covering properties of the pigment, the further and
altogether distinct result of imparting to the paint considerably greater freedom in
working that is to say-the paint leaves the brush much more readily.
The proportions which I prefer to use, but to which I would have it distinctly
understood I do not in any way confine myself, are as follows:-
K narts by weight of lead sulphate.

page_text: of material treated, the weight of the edge runners, and the speed of the mill, so
that no definite time can be stated; but to ensure the best results, the mixture, (of
which the density before grinding was about 112 pounds to the cubic foot) should
be ground until it acquires a density of about 200 pounds to the cubic foot. This,
under ordinary circumstances, will take from one quarter of an hour to one half of
an hour. When thoroughly incorporated by the grinding and pressure the product
is ready to be ground with oil in the customary way to form a paint.
The lead sulphate may be produced direct from metallic lead by submitting
small feathers or flakes of metallic lead to the alternate action of dilute acetic acid
and of atmospheric air whereby a solution of lead acetate is produced to which
sulphuric acid is added to precipitate the lead as sulphate. Although I prefer to
use lead sulphate produced in this manner such mode of production constitutes no
part of my Invention.
Having now particularly described and ascertained the nature of the said
Invention and in what manner the same is to be performed I declare that what
I claim is :-
1. The combination, or incorporation together, of lead sulphate, "zinc white"
(zinc oxide or zinc sulphide or a mixture of the two) and of barium sulphate to
constitute a white pigment, as specified.
2. The manufacture of a white pigment by incorporating together, by pressure
and friction produced by grinding, a mixture of lead sulphate, " zinc-white" (zinc
oxide or zinc sulphide or a mixture of the two) and barium sulphate, substantially
as herein specified.
8. The manufacture of a white pigment by incorporating together, by pressure
and friction produced by grinding in a dry state, a mixture of lead sulphate, "zinc
white" (zinc oxide or zinc sulphide or a mixture of the two) and barium sulphate
in about the proportions substantially as herein specified.
Dated this 20th dow of T….!.. 10ur