Improved Process for Producing Artificial Stone for Lithographio and other Purposes.
Year: 1898

page_text: Date of Application, 27th Dec., 1898
Complete Specification Left, 27th Sept., 1899-Accepted, 25th Nov., 1899
PROVISIONAL SPECIFICATION.
Improved Process for Producing Artificial Stone for Lithographio and
other Purposes.
We, FRLDERICK GEORGE BATL, of 55 and 56, Chancery Lane, in the County
of London, Commission Agent, ALBERT CHARLES OAKES, of 7, Martin's Lane,
Cannon Street, London, EC, Agent, and TноMAS MATHIESON THOM, of 59, Loid-
ship Lane, Wood Green, in the County of Middlesex, Lithographer, do hereby
declare the nature of this invention to be as follows:-
a
The chief object of this invention is to produce an artificial stone which may
be used as a lithographic stone, but the invention may be applied to the produc-
tion of stone for any other purpose to which such a stone may be applicable
Many attempts have been made to produce an artificial stone suitable for
lithographic pui poses, but hitherto without success
A leading feature in the manufacture of these stones has been the treatment
of the agglomerate, in block form, with carbonic acid gas, and it is thought that
the prohibitive puce of this gas has been one reason of non-success. Among
other reasons, it is thought, is the impure character of the materials employed,
and the present invention consists in a series of operations having in view the
obtaining of all the materials in a state of the greatest punty, and at a cheap
ate
By the present invention, waste products may be employed for the purpose
in view, such waste product being, sav, maible chippings, which may be con-
sidered the purest form of limestone obtainable
This limestone is burned to convert it to lime, and during the calcming,
carbonic acid is produced in a cheap and pure form, and is stored for the purpose
of being used again to impregnate blocks of agglomerate made from the lime
The impregnating of an agglomerate mass in the form of slabs on blocks with
carbonic acid is well known, and docs not, at this date, form proper subject matter
foi a patent
In carrying out this invention a gas producer of the Dowson type is filled with
coke or other carbonaceous material, and it is worked with oxygen and steam, in
place of air and steam, so that the resulting gas will be caibonic oxide and
hydrogen.
This gas, mixed with a further supply of oxygen, is used to calcine the pure
limestone in a suitable kiln, suitable means being provided to continuously
feed the kiln with limestone, without allowing air to enter. In like mannei,
suitable means will be provided for withdrawing the burned lime without allowing
an to enter the kiln.
The carbonic acid produced during this operation is collected cooled, and
washed, and is then stored for future use.
The lime is slaked, sieved, and worked up, and, when thoroughly mixed, 18
submitted to sufficient pressure to to consolidate it into blocks or labs of cop-
venient size in suitable moulds.

page_text: The blocks of slabs are allowed to dry for some time, and are then placed in a
suitable box or chamber, where they are submitted to the action of carbonic
acid.
This acid is forced into the chamber by a pump, a pressure of from 10 to 20
atmospheres being produced, and the blocks are allowed to remain therein until
they are converted into a solid block of carbonate of lime
If desired, the blocks may be placed in water into which the carbonic acid 18
forced by the pump as before mentioned.
Dated this 27th day of December 1898
NEWTON & SON,
Agents for the Applicants.
Improved Process for Producing Artificial Stone for Lithographic and
other Purposes.
We, FREDERICK GEORGE BATI, of 55 and 56, Chancery Lane, in the County
of London, Commission Agent, ALBIRT CHARLES OAKES, of 7, Martin's Lane,
Cannon Street, London, EC, Agent, and TOMAS MATHILSON THом, of 59, Loid-
shup Lane, Wood Green, in the County of Middlesex, Lithographer, do hereby
declare the nature of this invention and in what manner the same 18 to be per-
formed, to be particularly described and ascertained in and by the following
statement.-
The present invention has reference to the production of artificial stone suit-
able foi use as stone for lithographic and other purposes
In the production of such stone, it is usual to take caustic lime, which, after
being slaked, is compressed into blocks oi slabs, the latter being finally treated
with carbonic acid gas.
This method has not however proved very successful, on account of the in-
different processes employed in calcining the limestone and in producing carbonic
acid gas
The present invention comprises a method of calciming the limestone, which
will produce caustic lime in a chemically pure condition, and, at the same time,
yield carbonic acid gas in sufficient punity and volume to provide for the treat-
ment, with the necessary pressure, of moulded slabs or blocks made from the lime,
without aid fiom any other souice.
According to this invention, limestone (say, marble chips, which is a paili-
cularly pure form) is calcined in a close kiln, with the aid of carbonic oxide and
hydiogen, to which is added a supply of oxygen gas
The cat bonic oxide and hydrogen may be conveniently obtained by means of
a gas producer of the Dowson type, which is filled with coke, or simulat car-
bonaceous material, and worked with oxygen and steam in place of air and
stram.
In the kiln, during the calcining operation, wherein the carbonic oxide,
hydrogen, and oxygen gases are used, and from which atmospheric air 18 care-
fully excluded, is formed the carbonic acid gas to be afterwards used for im-
pegnating the slabs.
This carbonic acid gas, which is diann off, washed, cooled, and stored until
required, 18 of exceptional purity, containing only as revealed by actual tests,
a very moderate percentage of oxygen and nitrogen
One experiment shows that, in 120 minutes from the time of lighting the kiln,

page_text: 81% carbonic acid gas has been produced with only 19% excess of nitrogen
and oxygen.
Other experiments have not given so perfect a result, but in all cases a sufhciency
of carbonic acid is obtained for impregnating, under pressure, all the slabs that
can be moulded from the limestone buint
After burning, the lime is slaked, sieved, and worked up, and, when thoroughly
mixed, is consolidated into blocks or slabs of suitable dimensions with the aid of
moulds.
If desired, vacuum pumps may be used for withdrawing the air from the
moulds, in advance of the material fed into them, by means of hoppers m the
usual way
Slight pressure only however is required in the moulds, the action of
the carbonic acid gas being ielied on, to give the equined hardness to the
stone.
The impregnation of the slabs is effected in a closed chamber, into which they
are introduced after drying, preferably in the open air, a pressure of 10 to 20
atmospheres being employed, and continued until the blocks are completely
converted into carbonate of lime.
If desued, the blocks may be placed in water, into which the carbonic acid is
forced by a pump as is usual in the diy method
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, we declare that what
we claim 18:-
1. The process of producing artificial stone, wherein limestone is calcined in
a closed kiln, from which an is excluded, by means of carbonic oxide, by diogen,
and oxygen, and wherein the carbonic acid gas so produced is used for impregnat-
ing blocks made from the calcined lime, substantially as above described
The method wherein limestone is calcined with carbonic oxide, hydrogen,
and oxygen, in a kiln from which atmospheric air is excluded, substantially as
described.
Dated this 18th day of September 1899.