Improvements in the Manufacture of Plaster or Cement.
Year: 1885

page_text: Improvements in the Manufacture of Plaster or Cement.
I JOHN THOMLINSON of the firm of Joseph Robinson and Company of Knothill
Works, Carlisle, Cement and Plaster Manufacturers do hereby declare the nature
of my Invention for "IMPROVEMENTS IN THE MANUFACTURE OF PLASTER OR
CEMENT" to be as follows:-
This Invention has for its object improvements in the manufacture of plaster or
cement.
For this purpose I take plaster stone or sulphate of lime and by the usual
processes I drive off water from it; I then add an imported mineral known as
tincal and obtain an intimate mixture of the two in a finely powdered state. I also
incorporate with these materials a proportion of powdered alum.
CARPMAEL & Co.,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in the Manufacture of Plaster or Cement.
I JOHN THOMLINSON of the firm of Joseph Robinson and Company of Knothill
Works Carlisle Cement and Plaster Manufacturers 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 has for its obiect improvements in the manufacture of plaster or

page_text: tincal and obtain an intimate mixture of the two in a finely powdered state. I also
incorporate with these materials a proportion of powdered alum.
I prefer to conduct the manufacture as follows:-
I grind the calcined gypsum in the usual manner to a fine powder I also in like
manner and separately grind the tincal. I mix the two powders in the proportion
of about 40 or 50 pounds of tincal to the ton of calcined gypsum; the proportions
may be varied, if the quantity of tincal employed be somewhat greater than is
stated above the cement will be hardened and if less be used the cement will be
comparatively soft. The mixture of the two powders should be very complete.
It should be mentioned that gypsum varies much in quality and that to attain a
uniform standard in respect to hardness varying proportions of tincal will have to
be used.
In place of grinding the gypsum after calcination it may be first ground and
then calcined.
In some cases I mix other materials as well as tincal with the calcined gypsum
thus a good cement is obtained from the following materials.
Finely powdered calcined gypsum
Finely powdered tincal
Finely powdered alum
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-
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one ton.
45 pounds.
15 pounds.
The cement thus made I call Robinson's cement; it is of a similar character to
the cements known as Keen's, Parian and Martins, cement and is adapted for use
in every way that these cements are used and for the making of fire proof ceilings
and for various other purposes.
The process which I have described is very economical as compared with
processes heretofore employed in producing like cements and Robinson's cement
can consequently be delivered in the market at a price which admits of its being
employed for purposes for which common lime plaster is now employed.
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
A cement consisting of calcined and powdered gypsum mixed with powdered
tincal and with or without other ingredients substantially as described.
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