AN IMPROVED PROCESS OF MANUFACTURING ARTIFICIAL STONE
Year: 1881

page_text: LETTERS PATENT to Ernest de Pass, of the Office for British and Foreign
Patents, GS, Fleet Street, in the City of London, Patent Agent, for an Inven-
tion of "AN IMPROVED PROCESS OF MANUFACTURING ARTIFICIAL STONE."
A communication from abroad by Robert Holden Stone, of New Street,
Brighton in the Colony of Vistoria
Citilin
PROVISIONAL SPECIFICATION left by the said Ernest de Pass at the
Office of the Commissioners of Patents on the 10th November 1SS1.
ERNEST DE PASS, of the Office for British and Foreign Patents, 68, Fleet Street,
in the City of London, Patent Agent. "AN IMPROVED PROCESS OF MANUFACTURING
ARTIFICIAL STONE." A communication from abroad by Robert Holden Stone, of
New Street, Brighton, in the Colony of Victoria, Civil Engineer.
The object of this Invention is to manufacture artificial stone by the formation
in an improved manner of silicate of lime (or of hydrosilicate of calcium) in situ
as the matrix or cementing medium, the said matrix being in chemical contact
with the silicious aggregates employed to form the bulk of the stone, and produced
by the action of heated water or heated solutions of lime permeating the mass
after it has been moulded into the blocks required, as hereinafter more particularly
described.
I first take as aggregates any natural silica or silicate, such as sand, disintegrated
quartz, or other silicous rocks or earths, a portion of which should be either
naturally in or reduced to an amorphous condition, whether or not in natural
combination with any metallic base; 1 next take lime, either quick lime (by
preference ground) or an equivalent of slaked lime, by preference in the form
of a pure hydrate (or hydroxide of calcium). These materials I mix (the aggregates
in various degrees of disintegration) so that their particles shall with those of the
lime employed reduce the volume of voids in the finished stone to a minimum. If
quick lime be used I employ a sufficient quantity of water with the aggregates to
cause its perfect hydration before the next stage of the process, and use it in such
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page_text: proportions only as necessary to thoroughly coat every particle of the aggregates,
no more being required.
I then thoroughly triturate the above materials with such a further quantity of
water only as required to form a mass of sufficient plasticity to render it capable
of being compacted by ramming or pressing in moulds of any form required, it
being advisable to avoid any excess of moisture beyond that necessary to perma-
nently compact the materials; the concrete mass is then moulded preferentially by
ramming in the required form when the moulds can be at once removed, turning
out the moulded piece to set on any suitable bed. To prevent carbonization of the
exterior of the stone while setting, it is advisable to wash the surface over with a
weak solution of silica in any convenient form (a dialysed solution being preferable),
thereby forming immediately a surface of silicate of lime.
The process of setting will ordinary occupy from 3 to 10 days, and is to enable
the blocks to be handled with safety, and although not necessary longer than to
set the surface, by preference I allow time enough for it to take place throughout
the mass.
I next place the blocks in baths or tanks of any suitable form, and immerse
them in water (by preference charged with lime or other solution of calcium) for
the purpose of preventing the immediate dissolving or washing out of the lime
near the surface of the stone; the tanks are then gradually heated by any suitable
appliance, as by steam pipes, and maintained at an average temperature of 200°
Fahrenheit, by preference 212°, until the requisite degree of hardness is acquired
throughout the mass, the_time_being_from 48 hours.to.6 days, the.combined.action
of the lime water and moist heat forming a solvent acting on the surfaces of the
aggregates, and with the amorphous portions of them forming, as is believed, the
matrix of silicate of lime. This action is believed to take place by the alkaline
base of calcium in solution by the continuous supply of water acting on the silica,
and forming an insoluble silicate of lime (or hydrosilicate of calcium) in an
analagous manner to the formation of other alkalime, but soluble silicates under
analogous conditions.
It is essential to the appearance and perfection of surface that no degree of heat
should be applied to subject the stone to the disintegrating action of steam by
expansion.
The following form and proportions of materials may be successfully employed
to form a good stone, but I do not confine myself to these precise details herein
given.
Sand (free from all
vegetable matter)
1
}}
70 to 80 per cent. by measure.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Ernest de Pass in the Great Seal Patent Office on the 10th
May 1882.
{f
ERNEST DE PASS, of the Office for British and Foreign Patents, 68, Fleet Street,
in the City of London, Patent Agent. AN IMPROVED PROCESS OF MANUFACTURING
ARTIFICIAL STONE." A communication from abroad by Robert Holden Stone, of
New Street, Brighton, in the Colony of Victoria, Civil Engineer.
The object of this Invention is to manufacture artificial stone by the formation
in an improved manner of silicate of lime (or of hydrosilicate of calcium) in situ
as the matrix or cementing medium, the said matrix being in chemical contact
with the silicious aggregates employed to form the bulk of the stone, and produced
by the action of heated water or heated solutions of lime permeating the mass
after it has been moulded into the blocks required, as hereinafter more particularly
described.
I first take as aggregates any natural silica or silicate, such as sand, disintegrated
quartz, or other silicious rocks or carths, a portion of which should be either
naturally in or reduced to an amorphous condition whether or not in natural
combination with any metallic base; I next take lime, either quick lime (by
preference ground) or an equivalent of slaked lime, by preference in the form of a
pure hydrate (or hydroxide of calcium). These materials I mix (the aggregates in
various degrees of disintegration) so that their particles shall, with those of the
lime employed, reduce the volume of voids in the finished stone to a minimum.
If quick lime be used I employ a sufficient quantity of water with the aggregates
to cause its perfect hydration before the next stage of the process, and use it in
such proportions only as necessary to thoroughly coat every particle of the
aggregates, no more being required.
The above materials are then thoroughly triturated with such a further quantity
of water only as required to form a mass of sufficient plasticity to render it capable
of being compacted by ramming or pressing in moulds of any form required, it
being advisible to avoid any excess of moisture beyond that necessary to perma-
nently compact the materials; the concrete inass is then moulded preferentially by
ramming in the required form when the moulds can be at once removed, turning
out the moulded piece to set on any suitable bed. To prevent carbonization of the
exterior of the stone while setting it, is advisable to wash the surface over with
a weak solution of silica in any convenient form (a dialysed solution being
preferable), thereby forming immediately a surface of silicate of lime. This portion
of the process is however not absolutely necessary, and is not claimed by me as a
portion of my Invention. The process of setting will ordinarily occupy from 3 to
10 days, and is to enable the blocks to be handled with safety, and although not
necessary longer than to set the surface by preference I allow time enough for it
to take place throughout the mass.
I next place the blocks in baths or tanks of any suitable form, and immerse
them in water (by preference charged with lime or other solution of calcium) for
the purpose of preventing the immediate dissolving or washing out of the lime
near the surface of the stone; the tanks are then gradually heated by any suitable
appliance, as by steam pipes, and maintained at au average temperature of
200 degrees Fahrenheit, by preference under 212°, until the requisite degree of
hardness is acquired throughout the mass, the time being from 48 hours to 6 days,
the combined action of the lime, water, and moist heat forming a solvent acting on
the surfaces of the aggregates, and with the amorphous portions of them forming,

page_text: as is believed, the matrix of silicate of lime. This action is believed to take place
by the alkaline base of calcium in solution by the continuous supply of water
acting on the silica, and forming an insoluble silicate of lime (or hydrosilicate of
calcium) in an analagous manner to the formation of other alkaline, but soluble
silicates under analogous conditions. It is essential to the appearance and
perfection of surface that no degree of heat should be applied to subject the stone
to the disintegrating action of steam by expansion.
The following form and proportions of materials may be successfully employed
to form a good stone,-
Sand (free from all
vegetable matter)
Amorphous silica or
} 70 to 80 per cent. by measure.
silicates as calcined 10 per cent. by measure.
clay
Quick lime reduced } 10 per cent. by measure.
to hydrate
Water
10 per cent. by measure.
I do not however confine myself to the precise details herein specified, such as
the precise proportions of the materials used nor to the time of their treatment, so
long as the nature of my Invention be retained, although in these particulars I
have stated those which I believe to be the best, nor do I claim the manufacture
of artificial stone by the admixture of limes and silicates, as I am aware that such
admixtures are already-in-use.
But what I do claim is the improved process of manufacturing artificial stone,
the essence of which consists in the use and application of heated water with or
without lime in solution to such combinations (of lime and silicates) to form a
matrix of silicate of lime or hydrosilicate of calcium, substantially as herein
described and explained.
In witness whereof, I, the said Ernest de Pass, have hereunto set my hand
and seal, this Ninth day of May, in the year 1882.
EDVESM
4122