IMPROVEMENTS IN THE MANUFACTURE OF PIGMENTS FOR COATING SURFACES. PROVISIONAL SPECIFICATION
Year: 1861

page_text: LETTERS PATENT to George Hallett, of 52, Broadwall, Lambeth, in the
County of Surrey, Antimony Refiner, and John Stenhouse, of 17, Rodney
Street, Pentonville, in the County of Middlesex, L.L.D., for the Invention
of "IMPROVEMENTS IN THE MANUFACTURE OF PIGMENTS FOR COATING
SURFACES.
PROVISIONAL SPECIFICATION left by the said George Hallett and John
Stenhouse at the Office of the Commissioners of Patents, with their
Petition, on the 26th January 1861.
We, GEORGE ITALLETT, of 32, Broadwall, Lambeth, in the County of Surrey,
Antimony Refiner, and JOHN STENHOUSE, of 17, Rodney Street, Pentonville,
in the County of Middlesex, L.L.D., do hereby declare the nature of the
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF PIGMENTS FOR COATING
SURFACES," to be as follows:-
Our Invention has for its object improvements in the manufacture of pig-
ments for coating surfaces.
For this purpose we employ native oxide of antimony or such native oxide of
antimony as may contain a small proportion of sulphuret of antimony which is
reduced to a fine powder, the impurities it contains, derived from its matrix or
gangue, are separated by picking and washing as far as practicable. The finely

page_text: powdered native oxide of antimony, after having been dried is calcined at a
red heat in open vessels or suitable furnaces with free access of air, till any
sulphur present has been expelled and the oxide has been converted into or
chiefly into antimonious acid. The calcined product consisting chiefly of
antimonious acid is then ground up with suitable oil or varnish or other
materials to admit of its being used as a paint. When it is thought
desirable other oxides, salts, or materials may be combined with the calcined
product consisting chiefly of antimonious acid thus prepared so as to form
pigments suitable for the coating of surfaces. We also take the common ore
of antimony called the grey sulphuret (the tersulphide of antimony of chemists)
either pure, or as it is occasionally found mixed with oxide of antimony, and
reduce it to fine powder, having previously separated it as completely as prac-
ticable from any adhering matrix or gangue; we then intimately mix it with
its own weight of oxide of zinc. The mixture is then introduced into close
vessels such as covered crucibles, or into suitable close furnaces, and is
subjected to a moderately strong red heat for about an hour (although we do
not confine ourselves to this period of time) until the mixture is merely
agglutinated but not fused. It is then removed from the furnace, allowed to
cool, and ground to fine powder, and calcined in suitable furnaces with free
access of air at a moderately red heat, care being taken not to fuse the mixture
which should be repeatedly stirred in order that the whole may be equally acted
on by the hot air. The process is known to be completed when no more
sulphurous acid gas is evolved. The mixture is then to be reduced to fine
powder, and constitutes a pigment. The close vessels employed in the first
operation are not absolutely necessary, but we prefer employing them as they
diminish the loss of antimony by volatilization. Though we have mentioned
that we employ equal quantities of oxide of zinc and sulphuret of antimony we
do not confine ourselves to these proportions, but vary the quantities of these
two compounds according to circumstances. The oxide of zinc employed in
these operations may be obtained from any of the known sources of that com-
pound; thus, for instance, we sometimes employ the white oxide of zinc
produced by the combustion of metallic zinc, sometimes one of the precipitated
oxides of zinc or that from roasted blende, or from any of the native or artificial
carbonates of zinc, and likewise the basic silicate of zinc, and in fact any com-
pound which when strongly heated or otherwise treated will yield oxide of zinc.
We likewise effect the decomposition of the su phuret of antimony by heating
it with metallic zinc, this we prefer to do by pouring a slender stream of
metallic zinc in a fluid state into fused sulphuret of antimony, and collect
the fumes which are given off during this operation in suitable condensing

page_text: chambers. These fumes when condensed constitute a pigment. We also
sometimes decompose the sulphuret of antimony by heating it with sulphate of
the oxide of zinc, and likewise with the chloride of zinc. If the pigments
formed by the combinations of the oxidized compounds of zinc and antimony
produced by any of the processes above described are mixed with their own
weight of oxide of lead or lead compounds yielding oxide of lead when heated,
or with other suitable quantities of oxide of lead, these mixtures when calcined
at a red heat yield yellow pigments of different shades of colour according to
the proportions in which the constituents have been employed and the tempe-
ratures to which they have been subjected. Instead of the common grey
native sulphuret of antimony we sometimes employ the purified sulphuret of
antimony, the crude antimony of commerce, which is the native sulphuret of
antimony freed from the impurities of its matrix by fusion at a low tempe-
rature. We sometimes also employ the so called glass of antimony, made by
gently heating to redness either of these sulphurets in open vessels. When
either the crude antimony of commerce or the antimonial glass is mixed in a
fine powder with oxide of zinc and is subjected to any of the processes above
described for treating the native sulphuret, the antimony is oxidized and deprived
of its sulphur, and pigments are produced containing zinc and antimony when
these are mixed with oxide of lead, and calcined yellow pigments are obtained.
We also take metallic antimony, and sometimes also the ore known in com-
merce as native metallic antimony. These we reduce to fine powder and
intimately mix them with their own weight or other suitable quantities of oxide
of zinc. When these mixtures are heated first in close vessels and subse-
quently after reduction to fine powder in open vessels, with free exposure to
air, the antimony absorbs oxygen, and combining with the oxide of zinc forms
pigments. The compounds thus formed, when calcined with their own weight
or any other suitable quantity of oxide of lead yield yellow pigments. When
native oxide of autimony happens to be mixed with a considerable proportion
of native sulphuret of antimony we reduce the whole to fine powder and
intimately mix it with oxide of zinc before subjecting it to calcination; the
addition of the oxide of zinc enables us to decompose the sulphuret of antimony
which is present. In this way a pigment is produced, which when calcined
with the requisite quantity of oxide of lead may be changed into a yellow
pigment. We likewise sometimes take pative oxide of antimony either pure or
when containing sulphuret of antimony, and intimately mix it with its own
weight of oxide of zinc, and calcine. If these substances are nearly free from
iron and other impurities the resulting pigment is nearly white, but if iron or
other impurities are present the pigment is more or less colored. When the

page_text: pigments produced in this way are calcined with the requisite quantity of oxide
of lead yellow pigments are produced. If native oxide of antimony, nearly
pure, or the antimonious acid obtained by calcining native oxide of antimony is
mixed with its own weight or other suitable quantity of oxide of lead, with or
without the addition of oxide of zinc and calcined, a yellow pigment is pro-
duced. We sometimes also take type metal or worn out types, and reducing
them to coarse powder intimately mix them with their own weight or other
suitable quantity of oxide of zinc and calcine them; yellow pigments are then
produced. We likewiso employ the native oxide of antimony or the more or
less pure antimonious acid obtained from it by the process above described
for the manufacture of a yellow pigment. This we produce by taking eight
parts of either native oxide of antimony or the above described antimonious
acid, more or less pure, four parts of either red lead or litharge (or six parts of
carbonate of lead) and two parts of oxide of zinc; these are all intimately
mixed in a state of fine powder, and are then calcined at a red heat in suitable
vessels or furnaces till a combination is effected and the yellow pigment is
produced. When this has been accomplished the mass is reduced to fino
powder, when a yellow pigment is obtained. We do not confine ourselves to
the quantities of the different materials above described, but the proportions
mentioned are found to answer very well. Sometimes we increase the quantity
of oxide or carbonate of lead, and at others omit the oxide of zinc altogether,
and by varying the proportions of tho ingredients pigments are obtained of
different shades of color.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said George Hallett and John Stenhouse in the Great Seal Patent
Office on the 26th July 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, GEORGE
HALLETT, of 52, Broadwall, Lambeth, in the County of Surrey, Antimony
Refiner, and JOHN STENHOUSE, of 17, Rodney Street, Pentonville, in the
County of Middlesex, L.L.D., send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-sixth day of January, in the year of our Lord
One thousand eight hundred and sixty-one, in the twenty-fourth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto us, the
said George Hallett and John Stenhouse, Her special licence that we, the
said George Hallett and John Stenhouse, our executors, administrators, and

page_text: assigns, or such others as we, the said George Hallett and John Stenhouse,
our executors, administrators, and assigns, should at any time agree with,
and no others, from time to time and at all times thereafter during tho
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 MANU-
FACTURE OF PIGMENTS FOR COATING SURFACES," upon the condition (amongst
others) that we, the said George Hallett and John Stenhouse, our executors or
administrators, by an instrument in writing under our or their hands and
scals, or under the hand and seal of one of us or them, 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
Scal Patent Office within six calendar months next and immediately after
the date of the said Letters Patent.
NOW KNOW YE, that we, the said George Hallett and John Stenhouse
do hereby declare the nature of the said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained in
and by the following statement thereof, that is to say:-
In carrying out our Invention we employ the common ore of antimony,
called the grey sulphuret (the tersulphide of antimony of chemists), either
pure, or as it is occasionally found mixed with oxide of antimony, and reduco
it to fine powder, having previously separated it as completely as practicable
from any adhering matrix or gangue. We then intimately mix it with its own
weight of oxide of zinc, the mixture is then introduced into close vessels, such as
covered crucibles, or into suitable close furnaces, and is subjected to a mode-
rate red heat for about an hour (although we do not confine ourselves to this
period of time), until the mixture is slightly agglutinated, or is on the point
of becoming so, but not fused. It is then removed from the furnace, allowed
to cool, and if at all agglutinated ground to fine powder, and calcined in
suitable furnaces with free access of air at a moderately strong red beat, care
being taken not to fuse the mixture, which should be repeatedly stirred, in
order that the whole may be equally acted on by the hot air. The process is
known to be completed when no more sulphurous acid gas is evolved. The
mixture is then to be reduced to fine powder and constitutes a pigment, and
when this pigment is ground up with oil it constitutes a paint. The close
vessels employed in the first operation are not absolutely necessary, but we
prefer employing them as they diminish the loss of antimony by volatilization.
Though wo have mentioned that we employ equal quantities of oxide of zino
and sulphuret cf antimony, and we prefer to do so, we do not confine our-

page_text: selves to these proportions, as they may be varied. The oxide of zinc employed
in these operations may be obtained from any of the known sources of that
compound. Thus, for instance, we sometimes employ the white oxide of zinc
produced by the combustion of metallic zinc, sometimes one of the precipi-
tated oxides of zinc, or that from roasted blende, or from any of the native
or artificial carbonates of zinc, and likewise the basic silicate of zinc, and in
fact any compound which when strongly heated or otherwise treated will yield
oxide of zinc. We likewise effect the decomposition of sulphuret of anti-
mony by heating it with metallic zinc, this we prefer to do by pouring a slender
stream of metallic zinc in a fluid state into fused sulphuret of antimony, and
collecting the fumes which are given off during this operation in suitable
condensing chambers. These fumes when condensed constitute a pigment, and
when ground up with oil a paint. We also sometimes decompose the sul-
phuret of antimony by heating it with sulphate of the oxide of zinc, and likewise
with the chloride of zinc. If the pigments formed by the combinations of the
oxidized compounds of zinc and antimony produced by any of the processes,
above described, are mixed with their own weight of oxide of lead, or lead
compounds yielding oxide of lead when heated, or with other suitable quan-
tities of oxide of lead, these mixtures when calcined at a red heat yield yellow
pigments of different shades of color, according to the proportions in which
the different constituents have been employed, and the temperatures to which
they have been subjected. When these pigments have been ground up with
oil they constitute paints. Instead of the common grey native sulphuret of
antimony we sometimes employ the purified sulphuret of antimony, the crude
antimony of commerce, which is the native sulphuret of antimony freed from
the impurities of its matrix by fusion at a low temperature. We sometimes
also employ the so-called glass of antimony made by gently heating to redness
either of these sulphurets in open vessels. When either the crude antimony
of commerce or the antimonial glass is mixed in a fine powder with oxide of
zine, and is subjected to any of the processes, above described, for treating the
native sulphuret, the antimony is deprived of its sulphur, and oxidized, and
pigments are produced containing zinc and antimony. When these are
mixed with oxide of lead, and calcined, yellow pigments are obtained. When
these pigments are ground up with oil they constitute paints. We also take
metallic antimony, and sometimes also the ore known in commerce as native
metallic antimony, thèse we reduce to fine powder and intimately mix them
with their own weight or other suitable quantities of oxide of zinc. When
these mixtures are heated first in close vessels, and subsequently after reduc-
tion to fine powder in open vessels, with free exposure to air, the antimony

page_text: absords oxygen, and combining with the oxide of zinc forms pigments. The
compounds thus formed, when calcined with their own weight or any other
suitable quantity of oxide of lead, yield yellow pigments. When these pig-
ments are ground up with oil they constitute paints. When native oxide of
antimony happens to be mixed with a considerable portion of native sulphuret
of antimony we reduce the whole to fine powder, and intimately mix it with
oxide of zinc before subjecting it to calcination, the addition of the oxide of
zine enables us to decompose the sulphuret of antimony which is present. In
this way a pigment is produced, which when calcined with the requisite quan-
tity of oxide of lead may be changed into a yellow pigment; this pigment
when ground up with oil constitutes a paint. We likewise sometimes take
native oxide of antimony or native oxide of antimony when containing sul-
phuret of antimony, and intimately mix it with its own weight, or any other
suitable quantity of oxide of zinc, and calcine. If these substances are nearly
free from iron and other impurities the resulting pigment is nearly white, but
if iron or other impurities are present the pigment is more or less colored.
When the pigments obtained in this way are calcined with the requisite quan-
tity of oxide of lead yellow pigments are produced. When these are ground
up with oil yellow paints are obtained. If native oxide of antimony or the
anhydrous antimonious acid obtained by calcining native oxide of antimony is
mixed with its own weight or other suitable quantity of oxide of lead, with or
without the addition of oxide of zinc, and calcined, a yellow pigment is pro-
duced, which when ground up with oil forms a paint. We sometime also take
type metal or worn out types, and reducing them to coarse powder intimately
mix them with their own weight or other suitable quantity of oxide of zinc
and calcine them. Yellow pigments are then produced, which when ground
with oil constitute paints.
In witness whereof, we, the said George Hallett and John Stenhouse,
have hereunto set our hands and seals, this Twenty-sixth day of July,
in the year of our Lord One thousand eight hundred and sixty-one.