IMPROVEMENTS IN THE PREPARATION OF MATERIALS USED IN THE MANU- FACTURE OF POTTERY, EARTHENWARE, AND CHINA, AND IN APPARATUS FOR THE SAME
Year: 1868

page_text: PROVISIONAL SPECIFICATION left by Joseph Samuel Forbes at the
Office of the Commissioners of Patents, with his Petition, on the
30th November 1868.
I, JOSEPH SAMUEL FORBES, of Stoke-upon-Trent, in the County of
Stafford, Engineer, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN THE PREPARATION OF MATERIALS USED IN THE MANU-
FACTURE OF POTTERY, EARTHENWARE, AND CHINA, AND IN APPARATUS FOR THE
SAME," to be as follows:-
My Invention relates to the pulverization of material and preparation
of "slop" and glazes for potters' use, and consists in the adaptation and
application to this purpose of the apparatus herein-after described by
means of which the materials are calcined and reduced as required by a
dry process, as herein-after described, and afterwards mixed when
necessary with water in certain proportions in order to bring the material
into the condition of "slop" fit for potters' use.
The materials required to be calcined are operated upon in a heating
chamber with a furnace at the front end and a wall with an outlet for a
chimney flue at the back. Flues are arranged so that when the furnace

page_text: is lighted the flames are carried along parallel flues under the floor of the
kiln and up side chambers into the interior of the same, by which the
heating chamber is brought to a red heat. A charge of material is then
calcined and withdrawn and a fresh charge introduced without the heat
of the furnace being materially reduced. A drying room is constructed
adjoining the kiln, the flues from which are connected with other flues
under the floor of the drying room, thereby drying the material as
required without the aid of another furnace.
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The next process is to grind the materials after they have been roughly
crushed by a stone-breaking machine. The materials required to be so
reduced are flint, Cornwall stone, Cornwall clay, Guernsey and Jersey
stone, felpspar, borax, and other materials that may be found desirable for
potters' use. The material having been roughly broken is delivered by a
hopper to crushing rollers, whence it is discharged into a chamber placed
over or adjoining a hopper to feed a pair of French buhr or other suitable
stones, whence after being ground it falls into a hopper and is delivered to
another pair of grinding stones, from which it passes into a closed
chamber or wash tub partly filled with water. In some cases I prefer to
use only one pair of stones. A horizontal shaft with a fan on it is
caused to revolve rapidly in the tub while the pulverized material is
passing from the stone into the tub, thereby mixing the water with the
ground material and forming it into a slop." The mixture or "slop"
is then passed through a series of sieves suitably agitated, and thence by
a pipe or trough conducted to the ordinary "arks" or reservoirs. When
the material is required in a dry state the wash tub and sieves are
dispensed with, and the hopper under the stones is connected with a
closed dry chamber from which the dry ground material is removed as
required. In the preparation of glazes the material is delivered to a
pair of crushing rollers placed over the grinding apparatus, and is after-
wards passed through a pair of stones as before stated, except that the
stones are smaller and caused to revolve more rapidly. From these stones
the material falls into a hopper underneath, by which it is conducted to a
riddle or screen, cylindrical in form, with a central shaft or axis carrying
one or more shelves which successively receive the ground material and
scatter it against the sides of the riddle through which a portion of the
material passes, the remainder falling upon a cone and being acted upon
by rapidly revolving brushes has all the light particles brushed through
the outer casing. The portion not sufficiently ground passes into a pipe
connected with an outer casing to be reground. In some cases I prefer

page_text: to use horizontal sieves suitably agitated, through which the ground dry
material passes into the hopper underneath. After the material has passed
through a sieve it falls into a hopper, and is conducted to another pair
of rapidly revolving stones of smaller diameter, into which is delivered
a regulated quantity of water, by which means the material is again
pulverized and delivered into a hopper placed below the stones in a
liquid condition ready for use.