IMPROVE- MENTS IN THE MANUFACTURE OF CEMENT FROM GYPSUM
Year: 1863

page_text: LETTERS PATENT to Fédor de Wyldé, of Trinity Square, Tower Hill, in
the County of Middlesex, for the Invention of "IMPROVEMENTS IN THE
Sealed the 18th September 1868, and dated the 20th March 1868.
PROVISIONAL SPECIFICATION left by the said Fédor de Wyldé at
the Office of the Commissioners of Patents, with his Petition, on
the 20th March 1863.
I, FEDOR DE WYLDE, of Trinity Square, Tower Hill, in the County of
Middlesex, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF CEMENT FROM GYPSUM," to be as follows:-
The gypsum is first roasted in an oven in the usual manner to drive off the
water. It is then broken into small lumps and soaked in a heated solution of
an alkaline silicate containing an excess of carbonated alkali. The solution
which I find to answer my purpose best is composed of silicate of potash, with
such an equivalent of carbonate of potash as will not precipitate the silica,
such as the following proportion :-Thirty-one ounces of silicate of potash, and
Such a solution
nine ounces of carbonate of potash to one gallon of water.
will have the specific gravity of about twelve hundred, but the proportions
require to be varied according to the purpose to which tho cement is to be
applied. The gypsum after having been soaked in such solution for twenty-
four hours is allowed to remain at rest for some days. It is then again
roasted at such a temperature as shall most conveniently approach without
attaining the fusing point of the silicate for the purpose of again driving off
the water. The material is then ground to the requisite degree of fineness.
Having thus briefly described my Invention it is to be understood that

page_text: what I claim is, the manufacture of cement from gypsum, with the addition of
silicate and carbonate of potash, in the proportions and under the conditions
herein-before mentioned.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Fédor de Wyldé in the Great Seal Patent Office on the
19th September 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FEDOR
DE WYLDE, of Trinity Square, Tower Hill, in the County of Middlesex, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of March, in the year of our Lord
One thousand eight hundred and sixty-three, in the twenty-sixth year of Her
reign, did, for Herself, Iler heirs and successors, give and grant unto me,
the said Fédor de Wyldé, Her special licence that I, the said Fédor de
Wyldé, my executors, administrators, and assigns, or such others as I,
the said Fédor de Wyldé, my executors, administrators, and assigns, should
at any time agree with, and no others, from time to time and at all times
thereafter during the 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 "Iм-
PROVEMENTS IN THE MANUFACTURE OF CEMENT PROM GYPSUM," upon the condition
(amongst others) that I, the said Fédor de Wyldé, my executors or adminis-
trators, by an instrument in writing under my, or their, or one of their hands
and seals, 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 Seal Patent Office within six calendar
months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said Fédor de Wyldé, do hereby declare
the nature the said Invention, and in what manner the same is to be
performed, be particularly described and ascertained in and by the fol-
lowing sta nent:-
The gypsum is first roasted in an oven in the usual manner to drive off the
Fater. It is then broken into small lumps and soaked in a solution of an
lkaline silicate, which it is preferable to use with an excess of carbonated
alkali. The solut on which I find to answer my purpose best is composed of
silicate of potash, with such an equivalent of carbonate of potash as will not
precipitate the salier such as the following proportions:--Thirty-one ounces

page_text: of silicate of potash, and nine ounces of carbonate of potash to one gallon of
water. Such a solution will have the specific gravity of about twelve hundred,
but the gravity requires to be varied according to the purpose to which the
cement is to be applied; for instance, in some cases it may be used of the
normal strength described, but for ordinary cement it may be used in the pro-
portion of one part of this solution to two parts of water. In cases where a
more slowly setting cement is required, sulphate of potash may be used in
combination with the carbonated alkali; by the aid of this salt the action of
the silicate upon the gypsum may be retarded to any extent that may be
found desirable. The gypsum after having been soaked in such solution for
twenty-four hours (a longer maceration may sometimes be desirable) may be
removed from the macerating tubs and allowed to remain at rest in compact
masses for the more perfect diffusion of the solution through the gypsum. It
is then again roasted at a temperature of from 800 to 400 Fahrenheit for
the purpose of again driving off the water. The material is then ground to
the requisite degree of fineness. Color may be introduced into the material
when required for decorative purposes.
The solution above described might be used in place of water for mixing
with the roasted gypsum at the time of application, but it is far more con-
venient and the results obtained are far better when the solution is used in
the manner before mentioned.
Having thus briefly described my Invention it is to be understood that
what I claim is, the manufacture of cement from gypsum, with the solution of
silicate and carbonate of potash, in the proportions and under the conditions
herein-before mentioned.
In witness whereof, I, the said Fédor de Wyldé, have hereunto set
my hand and seal, this Nineteenth day of September, in the year of
our Lord One thousand eight hundred and sixty-three.
0 As witness,
RICHARD SILVESTER,
Patent Agent,
13, Warwick Court,
Gray's Inn, W.C.
FÉDOR DE WYLDÉ. (L.S.)