A CERTAIN IMPROVEMENT IN POTTERS' GLAZES
Year: 1870

page_text: LETTERS PATENT to Edward Wood, of Port Hill, near Burslem, in
the County of Stafford, and Harry Coghill, of Newcastle-under-
Lyme, in the same County, Merchants, for the Invention of "A
CERTAIN IMPROVEMENT IN POTTERS' GLAZES,"
Sealed the 29th April 1870, and dated the 7th March 1870.
PROVISIONAL SPECIFICATION left by the said Edward Wood and
Harry Coghill at the Office of the. Commissioners of Patents,
with their Petition, on the 7th March 1870.
We, EDWARD WOOD, of Port Hill, near Burslem, in the County of
Stafford, and HARRY COGHILL, of Newcastle-under-Lyme, in the same
County, Merchants, do hereby declare the nature of the said Invention
for "A CERTAIN IMPROVEMENT IN POTTERS' GLAZES," to be as follows:-
We propose to substitute oxide of zinc in lieu of lead and the other
poisonous substances hitherto used in potters' glazes. We take a
combination of boracic acid and soda or the equivalents of borate of
soda or borate of lime fused with clay, china stone, carbonate of lime and
flint in the usual manner, and to a specific quantity of this fused material
we add china stone, flint, carbonate of lime, and oxide of zinc or
carbonate of zinc according to the description of ware to be glazed. By

page_text: the addition of the oxide of zinc or carbonate of zinc we not only
dispense with the use of poisonous substances, but we also obtain a
superior glaze whether for china or other pottery ware.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Edward Wood and Harry Coghill in the Great
Seal Patent Office on the 1st September 1870.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, EDWARD
WOOD, of Port Hill, near Burslem, in the County of Stafford, and
HARRY COGHILL, of Newcastle-under-Lyme, in the same County,
Merchants, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Seventh day of March, in the year
of our Lord One thousand eight hundred and seventy, in the thirty-
third year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said Edward Wood and Harry Coghill,
Her special licence, that we, the said Edward Wood and Harry
Ooghill, our executors, administrators, and assigns, or such others
as we, the said Edward Wood and Harry Coghill, 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 "A CERTAIN
IMPROVEMENT IN POTTERS' GLAZES," upon the condition (amongst others)
that we, the said Edward Wood and Harry Coghill, our executors or
administrators, by an instrument in writing under our, or their, or one
of their hands and scals, 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 we, the said Edward Wood and Harry Coghill,
do hereby declare the nature of our said Invention, and in what manner
the same is to be performed, to be particularly described and ascertained
in and by the following statement :-

page_text: The nature of our Invention consists in the production of good and
economical potters' glazes whether for china or other pottery ware while
dispensing with lead and the other poisonous substances hitherto used
in their preparation, and our improvement consists in the substitution of
oxide of zinc or carbonate of zinc in lieu thereof, operating for example
as follows:-We take a combination of boracic acid and soda crystals, or
the equivalents of borax, tincal, or borate of lime, but preferably, boracic
acid and soda, and we mix well together say seventy-five pounds weight
of boracic acid, seventy-five pounds of crushed soda crystals, seventy-five
pounds of ground Cornwall stone, sixty pounds whiting or carbonate of
lime, thirty pounds ground flint, and twenty-five pounds of china clay.
We fuse this combination in a frett kiln or reverberatory furnace, and
to every four hundred and fifty pounds weight of this frett or glass we
add one hundred and fifty pounds of ground Cornwall stone, forty pounds
of china clay, twenty pounds of ground flint, twenty pounds of whiting
or carbonate of lime, and twenty pounds of pure oxide of zinc or
carbonate of same, and grind the same in water into an impalpable
powder. The glaze is then ready for use and may be applied to the ware
in the same manner as ordinary glazes.
Having now described and ascertained the nature of our said Invention
and in what manner the same is to be performed, we would have it
distinctly understood that the proportions above given are simply
approximative, and that we do not confine ourselves thereto, nor to the
use of all the ingredients above specified, as some may be eliminated and
others added without any departure from our Invention, which we declare
to be and we claim, the use of oxide or carbonate of zinc as a flux and
dipping medium in the manufacture of potters' glazes.
In witness whereof, we, the said Edward Wood and Harry Coghill,
have hereunto set our hands and seals, this Thirtieth day of August,
in the year of our Lord One thousand eight hundred and
seventy.