An Improvement in the Manufacture of Sulphate of Lead Pigment.
Year: 1893

page_text: Date of Application, 17th June, 1893
Complete Specification Left, 16th Mar., 1894-Accepted, 17th July, 1894
PROVISIONAL SPECIFICATION.
An Improvement in the Manufacture of Sulphate of Lead Pigment.
I, ALICE MACDONALD of No. 13 Ladbroke Grove, Notting Hill in the County
of Middlesex, Spinster, do hereby declare the nature of this invention to be as
follows:-
When sulphate of lead fumes are condensed, it is usually necessary to wash the
product so as to remove impurities, and thereafter to dry the washed material, a
process which occupies considerable time and involves great labour and expense.
My invention relates to means of treating the condensed fumes so as to produce a
clear white pigment without washing. For this purpose, when the fumes have
been condensed in water, I squeeze out a large proportion of the water by filter
pressing, and thus obtain the fumes in a condition of stiff paste. When the fumes
are deposited dry, this filtering operation is unnecessary. I charge the filtered
paste or the dry fumes into a retort or furnace and subject the material to a red
heat in presence of air. Thus many of the impurities are burnt off, decomposed
or oxidised, leaving the product of increased density and of suitable quality for
pigment purposes.
Dated this 17th day of June 1893.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
An Improvement in the Manufacture of Sulphate of Lead Pigment.
I, ALICE MACDONALD, of No. 13 Ladbroke Grove, Notting Hill, in the County
of Middlesex, Spinster, 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 :-
When sulphate of lead fumes are condensed it is usually necessary to wash the
product so as to remove impurities, and thereafter to dry the washed material, a
process which occupies considerable time and involves great labour and expense.
My invention relates to means of treating the condensed fumes so as to produce a
clear white pigment without washing. For this purpose, when the fumes have
been condensed in water, I squeeze out a large proportion of the water by filter
pressing and thus obtain the fumes in a condition of stiff paste. When the fumes
are deposited dry, this filtering operation is unnecessary.
I charge the filtered paste or the dry fumes into a retort or furnace and subject
the material to a heat of about 450° F. upwards in presence of air or air and
steam. It is preferable to keep the temperature as near 450° F. as possible so as
to prevent fritting or caking which would entail regrinding. Thus many of the
impurities are burnt off, decomposed or oxidised, leaving the product of increased
density and of suitable quality for pigment purposes.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I
claim is :-
In the manufacture of sulphate of lead pigments the herein described process

page_text: for purifying the sulphate of lead fumes by drying them when necessary and
subjecting them to furnace action.
Deted this 16th day of March 1804
ABEL & IMRAY,
Agents for the Applicant.