Improvements in the Manufacture of Pearl Hardening or Satin Spar.
Year: 1897

page_text: Date of Application, 20th Jan., 1897
Complete Specification Left, 13th Oct., 1897- Accepted, 27th Nov., 1897
PROVISIONAL SPECIFICATION.
Improvements in the Manufacture of Pearl Hardening or
Satin Spar.
We, WILLIAM BROTHERS of Higher Clewes Chemical Works, Rawtenstall, in the
County of Lancaster, Manufacturing Chemist and WILLIAM MALAM BROTHERS of
Higher Clewes Chemical Works aforesaid, Technical Chemist, do hereby declare the
nature of this invention to be as follows:-
This invention relates to the manufacture of a crystalline sulphate of lime used in
the manufacturing or finishing of paper textile fabrics and other articles known
variously as satin spar, pearl hardening and annaline.
It consists essentially in dissolving gypsum or other sulphate of lime either as a
natural or produced as a waste or bye product in boiling hydrochloric acid then
filtering the solution to remove foreign matters or impurities and subsequently
crystallizing or separating out in the form of crystals the sulphate of lime.
In carrying out the invention we take gypsum or other sulphate of lime preferably
that formed as a waste or bye product in certain manufactures. This sulphate of lime
we treat or boil in a suitable vessel with hydrochloric acid (HCl) until dissolved
therein. This solution is passed through a filter of glass wool or other suitable
filtering medium by which all insoluble impurities or foreign matter mixed therewith
are removed. The clear liquor is then passed over shallow vessels or slabs to cool or
into other suitable cooling vessels and the sulphate of lime crystallizes out.
The remaining liquor being mainly hydrochloric acid is pumped back into the
boiler or heating vessel and used again with a fresh charge of the material to be
treated.
1004
WM. P. THOMPSON & Co.,
6, Bank Street, Manchester, Patent Agents.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Pearl Hardening or
Satin Spar.
We, WILLIAM BROTHERS, of Higher Clewes Chemical Works, Rawtenstall, in the
County of Lancaster, Manufacturing Chemist, and WILLIAM MALAM BROTHERS, of
Higher Clewes Chemical Works, aforesaid, Technical 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 :--
This invention relates to the manufacture of a crystalline sulphate of lime used in

page_text: the manufacturing or finishing of paper textile fabrics and other articles, known
variously as satin spar or pearl hardening.
It consists essentially in treating or boiling gypsum or other sulphate of lime, in
boiling hydrochloric acid, either by itself or with the addition of water, and subsequently
separating out or crystallizing the sulphate therefrom in the form of fine crystals.
The invention is primarily intended to be applied to sulphate of lime, obtained in
a more or less impure state, as a waste or bye product in certain manufactures, though
it may also be applied to gypsum or other natural sulphate of lime.
The lime material to be treated may first be washed in water to remove any
impurities, capable of being so removed, and it may also be treated with sulphuric
acid if desired, to convert into sulphate any free or carbonate of lime that may be
present.
In carrying out the invention, we boil a quantity of hyrochloric acid (HC1) with or
without the addition of water in a suitable vessel, and to this we add the lime
material to be treated, either dry or wet as found most convenient. The lime material
is acted upon by the boiling liquor and becomes crystalline, and we continue adding
it to the boiling liquor, until the contents of the vessel become thickish. The mass
may be boiled until it is all crystalline in the open vessel, or if found to give better
results, the vessel may be closed, and the boiling take place under pressure.
If desired, the lime material may be first mixed with the hydrochloric acid cold,
either by itself or with the addition of water, and then boiled either in an open
vessel or under pressure, but we at present prefer to add the said material to the
boiling liquor.
During the boiling the mass may be agitated to assist crystallization.
After the boiling the mass is transferred to a vacuum filter, filter press or other
suitable form of filter, and the solid matter consisting of crystalline sulphate of lime
is taken out.
The clear liquor obtained from such filters, is then passed into shallow vessels or
slabs to cool, or into other suitable cooling vessels, and the sulphate of lime in solution
therein, crystallizes out.
The remaining liquor being mainly hydrochloric acid, is pumped back into the
boiler or heating vessel, and used again with a fresh charge of the material to be
treated.
In a modification of the process only sufficient of the raw sulphate of lime is.
dissolved in the boiling acid, with or without the addition of water so as to keep the
solution in a clear condition, and this solution is then run into shallow vessels or
slabs to cool, when the sulphate crystallizes out, the remaining liquor being pumped
back again as before, but we prefer the former process, as giving a larger
yield.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, we declare that what we
claim is
The process of producing or manufacturing pearl hardening, satin spar or other
sulphate of lime having a cystalline form, by boiling the natural or waste sulphate
of lime or gypsum in hydrochloric acid, with or without the addition of water, and
separating out the sulphate therefrom in the form of fine crystals, substantially as
described.
D
1
1021
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