IMPROVEMENTS IN THE MANUFACTURE OF CEMENT
Year: 1862

page_text: LETTERS PATENT to Joseph Duke and John Cleaver, both of Puriton, in
the County of Somerset, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF CEMENT."
Sealed the 13th January 1863, and dated the 21st October 1862.
PROVISIONAL SPECIFICATION left by the said Joseph Duke and John
Cleaver at the Office of the Commissioners of Patents, with their
Petition, on the 21st October 1862.
We, JOSEPH DUKE and JOHN CLEAVER, both of Puriton, in the County
of Somerset, do hereby declare the nature of the Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF CEMENT," to be as follows:-
This Invention has for its object improvements in the manufacture of
cement. For this purpose I first calcine white or blue lias, limestone, moun-
tain limestone, or other carbonate of lime, and having slacked the resulting
lime, I mix it with slate clay, potter's clay, pipe clay, porcelain clay, fire clay,
or other silicates of alumina, and I intimately combine these materials in a
finely-divided state in a wash mill with sufficient water to hold them in sus-
pension. The mixture is run into settling pits, and when it has settled the
water is run off, and the residuum is dried and burnt until the silica combines
with the lime; it is then ground fine and is fit for use as cement. Sulphate of
lime or gypsum, when deprived of its water of crystallization, may be employed
in combination with the above clays and silicate of lime. If soft carbonates

page_text: of lime, such as chalk, be employed, it need not be burnt before mixing it with
the clays or soluble silicates, but the use of roasted white or blue lias or moun-
tain limestone is preferred.
The novel features in the above processes are, first, the producing cement
from potter's clay, pipe clay, porcelain clay, fire clay, and other soluble silicates
of alumina by mixing them with calcareous materials, and afterwards, as
above described, suspending the materials in water when intimately divided
and mixed; and, secondly, the calcining the calcareous material before mixing
it with the clay in combination with the suspending the materials in water
when intimately divided and mixed.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joseph Duke and John Cleaver in the Great Seal Patent
Office on the 21st April 1863.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, JOSEPH
DUKE and JOHN CLEAVER, both of Puriton, in the County of Somerset, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of October, in the year of our
Lord One thousand eight hundred and sixty-two, in the twenty-sixth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
us, the said Joseph Duke and John Cleaver, Her special licence, that we, the
said Joseph Duke and John Cleaver, our executors, administrators, and
assigns, or such others as we, the said Joseph Duke and John Cleaver, our
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 "IMPROVEMENTS IN THE MANUFAC-
TURE OF CEMENT," upon the condition (amongst others) that we; the said Joseph
Duke and John Cleaver, our executors or administrators, by an instrument
in writing under our or their hands and seals, or under the hand and seal of
one of us or them, 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.

page_text: NOW KNOW YE, that we, the said Joseph Duke and John Cleaver, do
hereby declare the nature of the said Invention, and in what manner the
same is to be performed, to be particularly described and ascertained in and
by the following statement thereof, that is to say:
This Invention has for its object improvements in the manufacture of cement.
For this purpose we first calcine white or blue lias, limestone, mountain
limestone, or other carbonate of lime, and having slacked the resulting
lime, we mix it with slate clay, potter's clay, pipe clay, porcelain clay, fire
clay, or other silicates of alumina, and we intimately combine these materials
in a finely-divided state in a wash mill with sufficient water to hold them in
suspension. The mixture is run into settling pits, and when it has settled
the water is run off, and the residuum is dried and burnt until the silica
combines with the lime; it is then ground fine and is fit for use as cement.
We proceed, by preference, as follows:-We add 3 to 4 parts of either white,
blue lias or mountain lime properly burnt to one part of slate clay, potter's
clay, pipe clay, porcelain clay, fire clay, or other silicate of alumina. These
materials are washed together, as before described, and then dried either in
the atmosphere or in a room, or on a stove; afterwards the materials are
placed in a kiln of ordinary construction, and burnt at such a temperature as
will cause a combination of the silicate of alumina with lime, that is to say,
they are burnt in the ordinary manner of burning Roman cement; and, lastly,
the materials are ground very fine through an ordinary pair of cement
stones, and the cement is fit for use. The silicates of alumina which we have
found to be suitable are those which are soluble in hydrochloric acid. In
some cases, when there is a deficiency of silica in the silicate, we add from 5
to 7 per cent. of finely-ground flint or glass to the mixture.
The novel features in the above process are, first, the producing cement
from potter's clay, pipe clay, porcelain clay, fire clay, and other silicates of
alumina, by mixing them with calcareous materials, and afterwards, as above
described, suspending the materials in water when intimately divided and
mixed; and, secondly, the calcining the calcareous material before mixing it
with the clay in combination with the suspending the materials in water when
intimately divided and mixed.
If soft carbonates of lime, such as chalk, be employed, it need not be burnt
before mixing it with the clays or soluble silicates, and in this case we employ
about 6 parts of soft carbonate of lime to one part of the silicate of
alumina, but the use of roasted white or blue lias or mountain limestone is
preferred.
When soft carbonate of lime is employed the novel feature in the process

page_text: is the producing cement from potter's clay, pipe clay, porcelain clay, fire clay,
and other silicates of alumina, by mixing them with calcareous material, and
afterwards, as above described, suspènding the materials in water when inti-
mately divided and mixed. Sulphate of lime or gypsum, when deprived of
its water of crystallization, may be employed in combination with the above
clays and silicate of lime.
In using sulphate of lime or gypsum deprived of its water, we add about
two parts in weight of the silicate of lime or cement prepared, as above
described, to one part of the sulphate of lime or gypsum, and this produces a
cement applicable to the internal coating of walls.
In witness whereof, we, the said Joseph Duke and John Cleaver,
have hereunto set our hands and seals, this Eighteenth day of April,
in the year of our Lord One thousand eight hundred and sixty-three.
JOSEPH DUKE
JOSEPH DUKE (10)
JOHN CLEAVER. (L.s.)