Sulphate of Baryta and other Sulphates and Substances and the Manufacture from Materials so Treated of White and Tinted or Coloured Pigments.
Year: 1887

page_text: Date of Application, 5th May, 1887
Complete Left, 4th Feb., 1888
Complete Accepted, 4th May, 1888
Sulphate of Baryta and other Sulphates and Substances and the
Manufacture from Materials so Treated of White and Tinted or
Coloured Pigments.
I JOHN COWDERY MARTIN of 209 The Grove Hammersmith in the County of
Middlesex, Chemist do hereby declare the nature of this invention to be as follows:-
The invention consists essentially in diffusing or incorporating oxide of lead or
commercial white lead with a mixture of Sulphate of Baryta and Sulphate of Lime
and to some extent with other substances and causing them to enter more or less into
combination by burning or crushing them together. It admits of various modifications,
either of the above sulphates may be used separately with the lead material but with
less effect, sulphide of lead which is convertable by roasting into sulphate and oxide
of lead may also be treated the carbonates may for some pigments be substituted for
the above named sulphates and sulphate of lead, or zinc or iron oxide and lime
(calcium oxide) may be used. White pigments may be produced by incorporating
sulphate of Baryta sulphate of Lime and White Lead together under edge runners or
other apparatus capable of exerting pressure when incorporating the materials, either
of the above sulphates being previously burnt to redness or not before incorporating
them.
White pigments are also produced by intimately mixing sulphide of lead
previously ground to powder with sulphate of Baryta and sulphate of lime or either
of them and lead oxide in a wet condition. A quantity of hydrochloric or other
suitable acid is added and the mixture dried and burnt or roasted. As much carbonate
of Lime is then added as would neutralise the acid used and the whole is boiled or
heated in water washed dried and crushed together. Tinted pigments may be
produced by burning lead oxide or white lead with the above sulphates. The materials
treated as above readily combine with chromic acid for the production of yellow and
orange pigments. Sulphate of Lime may be simply mixed with White Lead or a
mixture of White Lead and sulphate of Baryta but the resulting pigments are not
equal in body to those above described.

page_text: 4
Improvements in Treating or Imparting Body or Opacity to
Sulphate of Baryta and other Sulphates and Substances and
the Manufacture from Materials so Treated of White and Tinted
or Coloured Pigments.
I JOHN COWDERY MARTIN of 209 The Grove Hammersmith in the County of
Middlesex Chemist 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 :-
I incorporate Sulphate of Baryta, or Sulphate of Lime, or a mixture of these
substances, with a small proportion of Calcium Oxide (Lime) preferably in the
hydrated condition of slaked lime, and I further incorporate these, and cause them to
enter more or less into combination, with one or other of the following substances,
by crushing them together, in either a wet or dry condition, under edge runners, or
other suitable crushing machinery. White lead (the commercial carbonate) zinc
oxide, Iron oxide, or zinc sulphide, may each be incorporated with a mixture of
calcium oxide and sulphate of Baryta, or a mixture of calcium oxide and sulphate of
Lime, also the above named salts of either Iron or zinc, may each be incorporated
with a small proportion of calcium oxide, without the addition of the above named
sulphates. The materials are more or less reduced in bulk by the treatment, and
become of increased density or specific gravity. When zinc oxide and calcium oxide
are crushed together in a wet condition, and afterwards dried, and again crushed, the
bulk of the mixture is reduced, and the density or specific gravity increased about
thirty per cent, or 150 parts become sufficiently reduced in bulk, to occupy little more
than the space occupied by 100 parts of zinc oxide previous to treatment. The
mixture also after combination, forius a tougher compound with oil, resembling white
lead in texture. The above named zinc and lead salts are employed to produce white
pigments, the Iron oxide tinted or coloured pigments. I also make a white pigment,
by adding calcium oxide to a mixture of sulphate of lead and zinc oxide, with or
without the addition of sulphate of Baryta. When making a white pigment with zinc
oxide, and sulphate of Baryta and sulphate of Lime, as above described, the
proportions of the several materials may vary, but I have obtained good results when
the zinc oxide forms two thirds of the weight of the pigment, the calcium oxide about
seven per cent, and the Sulphate of Baryta, or equal parts of this and Sulphate of
Lime, the remainder, but the proportion of sulphate of Lime, or Baryta, may be
largely increased. Similar proportions of the calcium oxide to that above specified
may be employed when using zinc oxide and calcium oxide alone, without the above
named sulphates, or when using Iron oxide and calcium oxide alone, without such
sulphates. Although I have given the proportions of the materials I have found to
answer well, I do not confine myself to these, as sometimes I use as little calcium
oxide as three per cent or less of the weight of the pigment, and sometimes as much

page_text: as thirty per cent may be used. The quantity I add to the mixture of sulphate of lead
and zinc oxide, is from three to seven per cent. When combining commercial white
lead in place of zinc oxide, with the materials above described, I reduce the quantity
of calcium oxide, according to the constitution or analysis of the white lead, and the
amount is best determined by experience. Although the materials forming the
several pigments may be crushed together at once in a dry condition as described, the
effect of the treatment is increased when these are crushed together wet, and again
after drying, they may however be simply mixed together dry without crushing, but.
with less effect. The sulphate of lime used I prefer to be so far calcined or burnt as
would prevent its setting, or becoming excessively hydrated when tested by adding
water to it. The calcium oxide may be added to each or either of the constituents of
the pigments, and crushed with them separately as described and the whole further
incorporated in the same manner or the calcium oxide may be added to a mixture of
the constituents of each pigment, and crushed with them in the same way. The use
as described of calcium oxide with Sulphate of Baryta or Sulphate of Lime produces
without the addition of the other above named metallic salts pigments a sufficient
proportion of the constituents of which combine chemically with and more or less
saponify the oil used as a vehicle for their distribution, and they may be combined with
any other pigment, with which Sulphate of Baryta not so treated, is now used.
I would have it understood that I do not claim the use of calcium oxide combined
with white lead alone, as I am aware the mixture when ground with oil becomes
hard with keeping, and I do not claim the use of calcium oxide combined
with any of the materials described, when these are also combined with tar, pitch, or
like resinous matters, as I am also aware a variety of such compositions have been
suggested for use on ships bottoms, nor do I claim the combination of calcium oxide,
with any of the materials herein named, when this substance exceeds thirty per cent
of the weight of the pigment of which it forms a part, as I am aware that in too great
an excess, its use is detrimental, nor do I claim the use of this substance further than
as hereinafter specified, and I do not claim the combination of sulphate of lead with
zinc oxide, or sulphate of Baryta but
Having now particularly described and ascertained the nature of my said
Invention and in what manner the same is to be performed I declare that what I
claim is
1st. Combining Sulphate of Baryta, or Sulphate of Lime, or a mixture of these
substances, with calcium oxide as described.
2. Combining a mixture of Sulphate of Baryta and calcium oxide, or a mixture
of Sulphate of Lime and Calcium oxide, with white lead, zinc oxide, Iron oxide, or
sulphide of zinc, as described.
3. Combining zinc oxide, or sulphide of zinc, with calcium oxide, as described.
4. Combining Calcium oxide, with Iron oxide, as described.
5. Combining calcium oxide, with a mixture of sulphate of lead, and zinc oxide,
with or without the addition of Sulphate of Baryta, as described.
6. The use of calcium oxide as described, for the purpose of causing a sufficient
proportion of each pigment to combine chemically with, and more or less saponify,
he oil used as a vehicle for its distribution..
Dated this 3rd day of February 1888