AN IN- PROVEMENT IN THE MANUFACTURE OF EARTHENWARE
Year: 1807

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JAMES
SPERSHOTT, of Shelton, in the County of Stafford, Clay Merchaut, send
greeting.
WHEREAS His most Excellent Majesty King the Third, by His Royal
Letters Patent under the Great Seal of Great Britian, bearing date at West-
minster, the Seventh day of February, in the forty-seventh year of His reign,
upon the Petition of me, the said James Spershott, did give and grant unto
me, the said James Spershott, my executors, administrators, and assigns, His
special licence, full power, sole privilege and authority, that I, the said James
Spershott, my executors, administrators, and assigns, and every of them, by
myself and themselves, or by my and their deputy or deputies, servants or
agents, or such others as I, the said James Spershott, my executors, admi-
nistrators, or assigns, should at any time agree with, and no others, from time
to timo and at all times thereafter during the term of years therein expressed,
should and lawfully might make, use, exercise, and vend, within that part of
His United Kingdom of Great Britain and Ireland called England, His Domi-
nion of Wales, and Town of Berwick-upon-Tweed, my Invention of "AN IN-
PROVEMENT IN THE MANUFACTURE OF EARTHENWARE," in such manner as to me, the
said James Spershott, my executors, administrators, or assigns, or any of them,
should, in their discretion, seem meet, and that I, the said James Spershott,
my executors, administrators, and assigns, should and lawfully might have
and enjoy the whole profit, benefit, commodity, and advantage from time to
time coming, growing, accruing, and arising by reason of my said Inven-

page_text: tion, for and during the term of years therein mentioned; in which said Letters
Patent there is contained a proviso obliging me, the said James Spershott,
by an instrument in writing under my hand and seal, to cause a particular
description of the nature of my said Invention, and in what manner the same
is to be performed, to be inrolled in His Majesty's High Court of Chancery
within one calendar month next and immediately after the date of the said
recited Letters Patent, as in and by the same (relation being thereunto had)
may more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
James Spershott, do hereby declare, that my said Invention of An Improve-
ment in the Manufacture of Earthenware, and the manner in which the
same is performed, is described and ascertained as follows:-
Take of gritt stone fit for the purpose (that which calcines the whitest, and
is the most free from common earth, lime, salts, acid, or any other impurity,
is the best), let it be calcined, then reduce it to a fine powder by grinding or
pounding. If need be, to make it more pure for particular purposes, calcine
it, and first reduce it to a coarse powder by grinding or pounding it a little,
then wash it in water; pour off the water; then reduce it to a fine powder
by grinding or pounding as aforesaid. As there are many sorts of clay used
of different qualities, and other articles mixed with it, and many different
qualities of glaze, and also carthenware made of many different qualities,
the different proportions of gritt stone that may be suitable may be ascer-
tained in the usual manner, as is done with flint stone, by making several
picces of earthenware with different proportions of gritt stone in it, and if it
proves to be too much, to reduce the quantity, and if to little, to increase it.
It may also be mixed with flint stone, and by that means used in a very small
proportion; from one sixth to one eighth part of gritt stone is the quantity I
have made use of, mixed with clay and other materials now in common use,
but more or less may be used as aforesaid. It is not to be understood that
gritt stone is always to be used in the same proportion as flint stones have
been used, because some of the gritt stone may be stronger or weaker than
flint stone, therefore either more of less may be required to answer the pur-
pose. Gritt stone is a stone consisting of sand agglutinated together; some
of it is very coarse in its grain and very soft, so as to be easily broken; others
are considerably hard, and very proper for building houses or other buildings,
and for grinding edge tools; others are fine in the grain, and so hard as to be
used for paving turnpike roads. Many of the bills in Staffordshire and other
parts of the kingdom are chiefly composed of this kind of stone; in general it
is of a brown, or reddish, or yellowish colour, in some places it is white or