A New Or IMPROVED COMPOUND FOR THE MANUFACTURE OF LIME-CEMENT OR PLASTER CAPABLE ALSO OF BEING USED AS AN ARTIFICIAL FUEL
Year: 1873

page_text: LETTERS PATENT to the Reverend Granville Hamilton Forbes, Rector
of Broughton, Northamptonshire, for the Invention of "A New Or
IMPROVED COMPOUND FOR THE MANUFACTURE OF LIME-CEMENT OR PLASTER,
Sealed the 14th October 1873, and dated the 19th May 1873.
PROVISIONAL SPECIFICATION left by the Reverend Granville Hamilton
Forbes at the Office of the Commissioners of Patents, with his
Petition, on the 19th May 1873.
I, the Reverend GRANVILLE HAMILTON FORBES, Rector of Broughton,
Northamptonshire, do hereby declare the nature of the said Invention
for "A NEW OR IMPROVED COMPOUND FOR THE MANUFACTURE OF LIME-CEMENT OR
PLASTER, CAPABLE ALSO OF BEING USED AS AN ARTIFICIAL FUEL," to be as
follows:-
My Invention consists in the mixture of coal tar, or the tar produced
in the distillation of a mixture of certain quantities of bitumen and
common coal with the refusc lime known as "foul lime" of gas works,

page_text: which is the lime that has been used in the purification of the gas. I
use this compound to make a valuable material for building purposes,
instead of common quicklime, or it may be used as a cement, or as a
substitute for plaster of Paris.
In carrying out my Invention I proceed as follows:-I thoroughly
mix the tar with about four times its weight of foul lime. (I prefer to
reduce the lime to a fine powder before mixing it with the tar.) I
afterwards press the mixture into blocks or balls; it is then burnt either
in a kiln, or grate, or stove, or in any other suitable and convenient
manner according to circumstances. After having been sufficiently
burnt it is allowed to to cool, and is subsequently reduced by crushing
to a fine powder. It is then fit for use either as a substitute for common
quicklime in making mortar, or concrete, or as a cement, or as a
substitute for plaster of Paris; in all these cases it is mixed with water
when used.
I have stated above the proportion of tar used to be about one-fourth
by weight of the lime, but though I prefer this quantity of tar I do
not wish to limit myself to this exact proportion.
1
When the compound is used as an artificial fuel it may be burnt with
a small quantity of coal or cinders, or wood, or any other convenient
fuel, and will be found to throw out great heat, and retain the heat for
a considerable time.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the Reverend, Granville Hamilton Forbes in the Great Seal
Patent Office on the 19th November 1873.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, the Reverend
GRANVILLE HAMILTON FORBES, Rector of Broughton, Northampton-
shire, send greeting.
2
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Nineteenth day of May, in the year of our 3
Lord One thousand eight hundred and seventy-three, in the thirty-sixth
year of Her reign, did, for Herself, Her heirs and successors, give and
grant unto the said Granville Hamilton Forbes, Her special licence
that I, the said Granville Hamilton Forbes, my executors, administrators,

page_text: and assigns, or such others as I, the said Granville Hamilton Forbes,
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 "A
NEW OR IMPROVED COMPOUND FOR THE MANUFACTURE OF LIME-CEMENT OR PLASTER,
CAPABLE ALSO OF BEING USED AS AN ARTIFICIAL FUEL," upon the condition
(amongst others) that I, the said Granville Hamilton Forbes, my executors
or administrators, by an instrument in writing under my, or their, or one
of their hands and seals, 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 I, the said Granville Hamilton Forbes, do hereby
declare the nature of my said Invention, and in what manner the same
is to be performed, to be particularly described and ascertained in and
by the following statement :-
My Invention has for its object an improved method of manufacturing
cement by intimately combining with the cement making material
before calcination such combustible matter as will render the compound
capable of burning readily in a kiln, or furnace, or stove, or grate.
The advantage and utility of my Invention thus is that I not only
improve the manufacture of cement by rendering the calcination of the
material from which it is made more easy, expeditious, and complete,
but also that I produce a fuel suitable for domestic and other purposes,
from the combination of which an excellent cement or plaster may be
made.
The foregoing statements particularly describe and ascertain the
nature of the said Invention, and indicate in what manner the same is
to be performed, or put in practice, and in further compliance with the
condition in the said Letters Patent contained, I will now further and
particularly describe and ascertain in what manner the same is to be
performed or carried out in practice.
I take the "foul" or refuse lime of gasworks which is the lime that
has been used in the purification of gas; I reduce it to a fine powder and

page_text: work it up thoroughly so as to mix the various substances contained in
the lime well together; I then add from one-fourth to one-third the
weight of coal tar or the tar produced in the distillation of a mixture of
coal and bitumen or natural pitch, and thoroughly amalgamate the
two substances.
There are various means by which the gas lime may be reduced to
powder and mixed with the tar, and I use any convenient means, but
I prefer to use a mortar mill for the purpose. After the materials have
been thoroughly amalgamated the compound is pressed into blocks or
pieces of any convenient size and shape, and to effect this I prefer to use
a mould and press.
But instead of adopting these means the compound may be pressed
by the action of the mill, and cut out of the pan in pieces.
After being pressed it is ready for use as fuel, or for the manufacture
of lime, cement, or plaster.
A small quantity of coal or other fuel may in either case be used
with it. When burnt in a kiln or furnace care should be taken not to
overburn it.
After having been sufficiently burnt it is reduced to a fine powder,
and is then ready for use for lime-cement or plaster.
In the above process the foul lime is used dry. Sometimes instead of
this I use the following process:-I grind the foul lime with sufficient
water to form it into a paste. This is afterwards dried either by artificial
heat or without, and when dry is reground and mixed in the mill with
the same proportion of tar as above specified. When thoroughly amal-
gamated the compound is pressed and moulded or cut into into pieces
as before described.
Sometimes instead of using either of the above methods of combining
the foul lime and the tar I use the process of absorption. Instead of
grinding the foul lime and mixing it with the tar in the mill, I take the
pieces or lumps of foul lime as they come from the gas purifier, and
having dried them thoroughly I place them in the tar, where I allow
them to remain until they have absorbed enough of the liquid for my
purpose.
After they are taken out the tar is allowed to drain from them. They
are then ready for burning either as fuel or for the manufacture of

page_text: cement. For drying the foul lime before it is placed in the tar I prefer
to use a moderate degree of artificial heat.
Having now particularly described and ascertained the nature and
object of my Invention, and in what manner the same is to be performed
or put in practice, I wish it to be understood that I claim the herein
described Invention of a new or improved compound for the manufacture
of lime-cement or plaster, capable also of being used as an artificial
fuel, as hercin-before set forth and described, wherein the following
are important points :-
First. The use of the aforesaid foul or refuse lime of gasworks in
combination with the aforesaid tar for the purpose of making an
improved lime-cement or plaster.
Secondly. The use of the above specified materials for the purpose of
making an artificial fuel capable when burnt of yielding a residue
valuable as a lime-cement or plaster.
In witness whereof, I, the said Granville Hamilton Forbes, have
hereunto set my hand and seal, this Seventeenth day of November,
in the year of our Lord One thousand eight hundred and seventy-
three.
0
Witness,
GRANVILLE HAMILTON FORBES. (L.S.)
HENRY SHAW,
Schoolmaster,
Broughton, Northamptonshire.