AN IMPROVE- MENT IN THE MANUFACTURE OF CLAY RETORTS
Year: 1859

page_text: LETTERS PATENT to Joseph Cliff, of Wortley, near Leeds, in the County
of York, Fire-brick Manufacturer, for the Invention of "AN IMPROVE-
MENT IN THE MANUFACTURE OF CLAY RETORTS."
Sealed the 19th June 1860, and dated the 29th December 1859.
PROVISIONAL SPECIFICATION left by the said Joseph Cliff at the
Office of the Commissioners of Patents, with his Petition, on the
29th December 1859.
I, JOSEPH CLIFF, of Wortley, near Leeds, in the County of York, Fire-
brick Manufacturer, do hereby declare the nature of the said Invention for
"AN IMPROVEMENT IN THE MANUFACTURE OF CLAY RETORTS," to be as follows:-
The object of this Invention is to prevent cracks, fissures, and roughness on
the surface of the retorts, and to get a smooth even polished and enamelled
surface, which shall prevent the escape or filtration of the gas and the adhesion
of carbon to the inner surface of the retort. I propose to effect this in the
following manuer :-I take the retort when in a proper state of dryness, and

page_text: make straight and level the inner and outer surfaces, at the same time leaving
them rough; I then take a mixture formed, as stated below, and cover over
the surfaces of the retort both inside and out with a coating of this mixture;
I then work this mixture into the surfaces of the retort so as to make it unito
perfectly with the body, and indeed become part and parcel thereof; and then
I smooth, level, and polish the same so as to get the improved enamelled surface
required. The mixture is made of powdered fine clay or flour of clay which has
been previously burnt at a high temperature and then mixed with water and
a little unburnt clay to the proper consistency. The powder of flint or sand-
stone and of burnt fire-clay of any kind will accomplish the same end, and any
of these may be used separately, or they may be used together in the mixture
which coats or covers the retort.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joseph Cliff in the Great Seal Patent Office on the
29th June 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
CLIFF, of Wortley, near Leeds, in the County of York, Fire-brick Manu-
facturer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-ninth day of December, in the year of our
Lord One thousand eight hundred and fifty-nine, in the twenty-third year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Joseph Cliff, Her special license that I, the said Joseph Cliff,
my executors, administrators, and assigns, or such others as I, the said Joseph
Cliff, 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 for "AN IMPROVEMENT IN
THE MANUFACTURE OF CLAY RETORTS," upon the condition (amongst others)
that I, the said Joseph Cliff, by an instrument in writing under my hand and
seal, should particularly describe and ascertain the nature of the said Inven-
tion, 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 I, the said Joseph Cliff, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement, that is to say:-
The object of this Invention of "An Improvement in the Manufacture of
Clay Retorts," is to prevent cracks, fissures, and roughness on the surface of
the retorts, and to obtain a smooth even-polished and semi-enamelled surface,
which will in a great measure prevent the escape or filtration of the gas and
the adhesion of carbon to the inner surface of the retort. In order to effect
the desired object, the inner and outer surfaces of the retort when in a proper
state of dryness are made level, but these surfaces must, at the same time,
be left sufficiently rough to admit of them receiving and holding a sufficient
coating of a composition or preparation of materials whereby a smooth, even,
and semi-enamelled surface will be produced when the retort has been burnt
or fired. The surfaces of the retort, both inside and out, are then covered with
a coating of a mixture, principally composed of powdered fire-clay or flour of
fire-clay which has been previously burnt at a high temperature. This
powdered fire-clay or flour of fire-clay is previously mixed with water, with the
addition of a small quantity of unburnt fire-clay, water being added only in
such quantities as will bring the mixture to the proper consistency to admit of
its being easily laid on and worked into the surfaces of the retort. The powder
of flint or sandstone or of burnt fire-clay of any kind will accomplish the same
end instead of the powdered fire-clay or flour of fire-clay, and any of these may
be used separately, or they may be used together in the mixture, with which the
surfaces of the retort may be coated or covered. When this preparation or mixture
is applied it must be well worked into every part of the surface of the retort,
so as to cause it to unite perfectly with the body, and indeed become part and
parcel thereof. The process of working in the preparation or mixture into the
surfaces of the retort must be continued until the surfaces become levelled,
smoothed, and polished so as to obtain a smooth face. When the retort is
sufficiently dry.it will be ready for firing in the usual manner, and when it has
undergone the operation of firing it will be found to have both inside and
outside a smooth unbroken semi-enamelled surface, which will in a great
measure prevent the adhesion of carbon or the escape of gas through the pores
of the clay.
Having now described my Invention of "An Improvement in the Manufac-
ture of Clay Retorts," and having explained the manner of carrying the same
into effect, I claim as the Invention secured to me by Letters Patent as afore-

page_text: said, the production of a smooth, even, and unbroken surface in or upon clay
retorts by the means above set forth.
In witness whereof, I; the said Joseph Cliff, have hereunto set my hand
and seal, this Twenty-eighth day of June, in the year of our Lord One
thousand eight hundred and sixty.
Signed, sealed, and delivered by the
said Joseph Cliff, in the presence of
JA. W. HAMILTON RICHARDSON, Solicitor,
Leeds.
JOSH. CLIFF. (L.S.)