AN IMPROVEMENT OR IMPROVEMENTS IN THE PREPARATION OR MANUFACTURE OF GYPSUM OR PLASTER OF PARIS
Year: 1853

page_text: LETTERS PATENT to Moses Cartwright, of Longton, in the County
of Stafford, Merchant, for the Invention of "AN IMPROVEMENT
OR IMPROVEMENTS IN THE PREPARATION OR MANUFACTURE OF GYPSUM
OR PLASTER OF PARIS."
Sealed the 12th July 1858, and dated the 13th January 1853.
PROVISIONAL SPECIFICATION left by the said Moses Cartwright
at the Office of the Commissioners of Patents, with his Petition,
on the 13th January 1853.
I, MOSES CARTWRIGHT, of Longton, in the County of Stafford,
Merchant, do hereby declare the nature of the said Invention for "AN
IMPROVEMENT OR IMPROVEMENTS IN THE PREPARATION OR MANUFACTURE OF
GYPSUM OR PLASTER OF PARIS" to be as follows:-
My Invention relates to that part of the manufacture of gypsum or
sulphate of lime called "boiling," which consists in applying heat to,
and at the same tine stirring, the finely powdered mineral; by these
means the water contained in the said mineral is volatilized, and the
said mineral becomes converted into the "plaster." of commerce. In
the ordinary method of manufacture the stirring of the powder is
effected by manual labour, whereby injury is done to the health of the
workman by the light powder which he inhales during respiration, and

page_text: longer. time is requisite than in my improved method. My method
consists in the use of a fixed circular closed or partially closed cistern
to contain the powdered gypsuni, which said cistern is heated by circular
or spiral flues situated underneath. A vertical shaft works in the said
cistern, and horizontal arms or stirrers on the said shaft effect the
stirring of the powder on the rotation of the said shaft.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Moses Cartwright in the Great Seal Patent Office
on the 12th July 1853.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
MOSES CARTWRIGHT, of Longton, in the County of Stafford, Merchant,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirteenth day of January, in the year of
our Lord One thousand eight hundred and fifty-three, in the sixteenth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto me, the said Moses Cartwright, Her special license that I, the
said Moses Cartwright, my executors, administrators, and assigns, or such
others as I, the said Moses Cartwright, 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 of "AN IMPROVEMENT OR IMPROVEMENTS IN
THE PREPARATION OR MANUFACTURE OF GYPSUM OR PLASTER OF PARIS,"
upon the condition (amongst others) that I, the said Moses Cartwright,
by an instrument in writing under my hand and seal, should par-
ticularly 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 I, the said Moses Cartwright, do hereby
declare the nature of the said Invention, and in what manner the same

page_text: is to be performed, to be particularly described and ascertained in and
by the following statement thereof (that is to say):
My Invention relates to that part of the manufacture of gypsum,
sulphate of lime, or plaster of Paris, called "boiling," which said pro-
cess of boiling" consists of the application of heat to the mineral in
a finely powdered state, the said powdered mineral being stirred during
the said application of heat. By the said process of "boiling" the
water contained in the sulphate of lime, as it is found in nature, is
volatilized, and the mineral is brought into an anhydrous state, in which
said state it constitutes the "plaster" or "plaster of Paris" of com-
merco. In the ordinary method of manufacture the stirring of the
powdered mineral during "boiling" is effected by manual labour,
whereby injury is done to the health of the workınan by the light
powder which he inhales during respiration, and longer stirring is
required than when the said stirring is effected by my improved method.
My said improved method is illustrated by the accompanying Drawing,
in which Figure 1, represents a vertical section, and Figure 2, a
horizontal section, of an apparatus for "boiling" gypsum according to
my Invention. The section Figure 2, is taken through the line a.
Figure 1; b, is the cistern in which the powdered mineral is placed;
the said cistern is fixed, and is of a circular or nearly circular figure, as
shewn in Figure 2, and is heated by a flue of the curved form repre-
sented; d, is the fire-place or furnace, the flame and heated air from
which pass along the flue c, in the direction indicated by the arrows,
and passes away by the flue e, indicated in Figure 2, in dotted lines;
the cistern b, may either be closed or partially closed at top; f, is a
vertical shaft which passes through the cover or top of the cistern b;
the said shaft works in the bearings g, h, and carries at its lower end
horizontal arms i, i, of which any desired number may be used. To the
said horizontal arms i, i, a series of scrapers or stirrers k, k, are attached;
rotatory motion is communicated to the shaft : from any convenient
driving power by means of the toothed wheel 7. By heating the powdered
natural gypsum, and stirring by the means described, it is "boiled" or
brought into the anhydrous state in which it is required in commerce.
Having now described the nature of my said Invention, and the

page_text: manner in which the same is to be carried into effect, I wish it to be
understood that I do not limit myself to the precise manner of carrying
my Invention into effect herein described and represented in the accom-
panying Drawing, as the same may be varied without departing from
the nature of my said Invention; but I claim the "boiling," or
dehydrating of natural or hydrated gypsum by heating the powder of
the same in a fixed circular or nearly circular cistern, closed or partially
closed, the said cistern being heated by flues and the said powder stirred
by stirrers actuated by machinery as herein described, and illustrated by
the accompanying Drawing.
In witness whereof, I, the said Moses Cartwright, have hereunto
set my haud and seal, this Eleventh day of July, in the year of
our Lord One thousand eight hundred and fifty-three.
Witness,
GEORGE SHAW.
MOSES CARTWRIGHT. (L.S.)