IMPROVEMENTS IN THE MANUFACTURE OF ARTIFICIAL STONE OR SLATE. AND IN COLORING THE SAME
Year: 1868

page_text: LETTERS PATENT to the Reverend Henry Highton, M.A., of 11,
Sussex Square, Brighton, in the County of Sussex, for the Inven-
tion of "IMPROVEMENTS IN THE MANUFACTURE OF ARTIFICIAL STONE OR
SLATE. AND IN COLORING THE SAME."
Sealed the 28th October 1868, and dated the 25th June 1868.
PROVISIONAL SPECIFICATION left by the Reverend Henry Highton
at the Office of the Commissioners of Patents, with his Petition,
on the 25th June 1865.
I, the Reverend HENRY HIGHTON, M.A., of 11
of 11 Sussex Square,
Brighton, in the County of Sussex, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF ARTIFICIAL
STONE OR SLATE AND IN COLORING THE SAME," to be as follows:-
This Invention has for its object improvements in the manufacture
of artificial stone or slate, and in coloring the same.
I carry out the Invention in the following manner-1 cast any
ordinary hydraulic cement containing clay and lime burnt together
and then ground, mixed if desirable with sand, gravel, burnt clay,

page_text: broken flints, or stones, into the required shape for a stone or slate,
then I steep the same in a solution of soluble silicate. If only the
parts near the surface require to be hardened the solution may be
concentrated to the ordinary commercial strength. If it is required
to be hardened more thoroughly the solution should be more dilute and
the cement steeped for a longer time As the lime in the cement takes
up the silica from the solution I supply it from time to time with
fresh quantities of silica in a shape easily soluble, that is, as a precipitate
or in the shape of a natural easily soluble silica, or else I remove the
alkali as it loses its silica and use it for redissolving fresh quantities
of silica in the well-known methods, supplying the cement with fresh
silicate. The precipitated silica for use as above described or otherwise
in the manufacture of artificial stone or slate may be advantageously
prepared by passing carbonic acid gas through a solution of alkaline
silicate. At the same time that the silica is precipitated the alkali is
converted into carbonate; it is afterwards again rendered caustic by
lime and used to dissolve a further quantity of silica.
I produce a soluble alkaline silicate by heating or long steeping of the
natural easily soluble silica found in certain beds near Farnham and other
localities in a solution of caustic alkali. I then employ the alkaline silicate
so obtained in the manufacture of artificial stone by processes which are
well understood. An artificial stone may be produced in this way
at a cheaper rate than when using an alkaline silicate made by the
methods at present in use.
After the cement has been sufficiently steeped to produce the required
degree of hardness it may be washed if désired to free it from the small
quantity of soluble silicate adhering to it, or a solution of some suitable
salt may be applied to the surface, such as a soluble salt of the earths
or metals, or a dilute acid may be applied to it; the best acids for
the purpose I find to be the oxalic, fluoric, fluozilicic, tartaric, boracic,
or phosphoric.
If it be desired to change the colour of the artificial stone or slate
manufactured as above described, I proceed as follows:-In order to
produce a good white I apply a solution of some metallic sulphate which
when decomposed by the lime in the cement will throw down a white
oxide, such as sulphate of zinc, magnesia, or alumina, and, then a solu-
tion of chloride of barium, the effect of which is to deposit within the
pores of the cement a brilliant white oxide of the metal and sulphate

page_text: of baryta; or the order of application of these solutions may be reversed.
Sulphuric acid may be substituted for the metallic sulphate, or to pro-
duce other colors a soluble salt of barium or other metal may be applied
and a solution of chromic acid. The salt of the inetal may be varied
to produce the required shade of color.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the Reverend Henry Highton in the Great Seal Patent
Office on the 24th December 1868.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, the
Reverend HENRY HIGHTON, M.A., of 11, Sussex Square, Brighton, in
the County of Sussex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-fifth day of June, in the year
of our Lord One thousand eight hundred and sixty-eight, in the
thirty-second year of Her reign, did, for Herself, Her heirs and suc-
cessors, give and grant unto me, the said Henry Highton, Her special
licence that I, the said Henry Highton, my executors, administrators,
and assigns, or such others as I, the said Henry Highton, my executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thercafter 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 "IMPROVEMENTS IN
THE MANUFACTURE OF ARTIFICIAL STONE OR SLATE, AND IN COLOURING THE
SAME," upon the condition (amongst others) that I, the said Henry
Highton, 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 Henry Hightou, do hereby
declare the nature of the said Invention, and in what manner the

page_text: same is to be performed, to be particularly described and ascertained in
and by the following statement thereof, that is to say:-
The
I carry out my Invention in the following manner-1. I mould
or cast hydraulic mortar or cement mixed with water (to which I
prefer to add a very little acid, by preference muriatic acid), and if
desirable with sand, gravel, burnt clay, broken flint stones, or other
suitable substances into any required shape as cement blocks have
heretofore been produced. If any plastic material be used with it it is
best to apply pressure or percussion in forming the block or slate. Then
at any time after the mass has become sufficiently solid I steep it in
a solution of soluble silicate, which should be supersaturated with soluble
silica by the addition of the requisite quantity of silica in a soluble form.
If only the parts near the surface require to be hardened the solution
may be concentrated to the ordinary commercial strength, but if it is
required that it should be hardened more thoroughly the solution should
be more diluted and the moulded article steeped for a longer time.
time of steeping may be varied from a few hours to weeks or months.
and if very great hardness be required towards the end of the process
the block may be dried and steeped again, and this operation repeated
several times in order to ensure the complete filling of the pores of the
block with silica. For the more perfect penetration of the silica it is
advisable in some cases to perforate the block or other moulded article
and to form elevations and depressions on the surface which may be
made to assume any ornamental forn, or to saturate the interior with
the silicate by the well-known means of atmospheric exhaustion as the
lime in the cement takes up the silica from the solution. I supply this
from time to time with fresh quantities of silica in a shape easily soluble,
that is, as a precipitate, or in the shape of a natural easily soluble silica,
or else I remove the alkaline liquid as it loses its silica and use it for
redissolving fresh quantities of silica by any of the well-known methods.
The hydraulic cement used may be made either of lime in conjunction
with clay or silica and alumina burnt together and then ground as it is
new ordinarily made, or as hydraulic cements were commonly made in
former times, by mixing lime with substances containing silica or alumina
in a shape in which it easily combines with lime to form a silicate of lime
or alumina, as pozzuola strass ashes or the natural soluble silica; or even
lime itself may be used instead of hydraulic cement, though it does not
form so strong a stone. Instead of steeping the block in silicate it may

page_text: be placed in a solution of soda or potash (either caustic or not) together
with soluble silica. The alkali if not used in a caustic state is made
caustic by the lime in the block, and will take up the silica and convey
it to the stone. This method avoids the expense and trouble of making
a soluble silicate separately, but takes a longer time.
I am aware that compounds containing hydraulic cement or lime have
been hardened by steeping in a silicate, and therefore I do not claim this as
new, but only when the silicate is used in combination with soluble silica,
as above described, by which process the same alkali is used to dissolve
and convey successive quantities of silica to the lime in the cement.
In constructing pavements it may be advisable in some cases to
combine the materials on the spot where the pavement is to be laid,
which materials may consist of a mixture of cement and stones or other
suitable materials, and then cover the surface with soluble silica and a
solution of soluble silicate. This application to the surface may be
renewed from time to time when desired.
Also according to my Invention I produce a soluble alkaline silicate
by heating or long steeping of the natural easily soluble silica found in
certain beds near Farnham and in other localities in a solution of caustic
soda or potash. This is best done in a close vessel in order to exclude
the carbonic acid contained in the air. At a boiling heat the alkali
need not necessarily be in a caustic state, but it is better if it is so. I
then employ the alkaline silicate so obtained in the manufacture of
artificial stone by the process herein described or other well-known
processes; or the natural mineral soluble silica may be heated in a
fufnace with alkali to form a soluble silicate in proportions and in a
manner well known.
I am aware that the mineral soluble silica has been used as above to
make a soluble silicate for the manufacture of soap, and also for forming
a stone by burning, and therefore I only claim the use of it for making
artificial stone by a wet process.
2. When the block of artificial stone has been sufficiently steeped as
before described to produce the degree of hardness required it may be
washed if desired in order to free it from the small quantity af alkali and
soluble silicate adhering to it; or a solution of some suitable salt may
be applied to the surface, such as a soluble salt of the earths or metals,

page_text: precipitate on the surface and in the pores, or a dilute acid may de
applied to it. The best acids for the purpose I find to be the oxalic,
fluoric, fluosilicic, tartaric, boracic, and phosphoric. The solution of the
soluble salt or the dilute acid may either be applied by a brush or similar
instrument, or the block may be dipped for a short time in the solution.
In either case the operation should be continued till the soluble silicate
on and near the surface has been decomposed by the soluble salt or
dilute acid.
I am aware that natural or artificial stone has been hardened by
applying successively to the surface first a soluble silicate and then
chloride of calcium or two other solutions mutually decomposing each
other and depositing an insoluble substance in the pores and on the
surface of the stone, and therefore I do not claim the application of a
soluble salt of the earths or metals or of a dilute acid after an application
of soluble silicate except in the case of blocks or slates made as above
described.
3. If it be desired to change the color of the artificial stone or slate
thus described I proceed as follows:-In order to produce a good white
I apply a solution of some metallic sulphate which when decomposed
by the lime in the cement will throw down a white oxide, such as a
sulphate of zinc, magnesia, or alumina, and then a solution of chloride
of barium or caustic baryta dissolved in water, which latter is best
applied hot, as caustic baryta is more soluble in hot than cold water.
The effect of this is to deposit a brilliant white oxide of the metal and
The
sulphate of baryta upon the surface and in the pores of the cement.
order of the solution may be reversed if necessary, or sulphuric acid may
be substituted for the metallic sulphate. To produce other colours a
soluble salt of barium or other metal may be first applied and then
dilute chromic acid. The salt of the metal may be varied to produce
the required shade of colour; or in some cases the chromic acid may be
omitted and a suitable soluble salt of a metal used alone. The sulphate
and other salts of copper and iron are useful for producing green and red
shades of color.

page_text: the surfaces of stone, and salts of iron and other metals for dyeing
artificial stone, and therefore I only claim the use of these methods of
coloring when applied to blocks of artificial stone or slate made as above
described.
In witness whereof, I, the said Henry Highton, have hereunto
set my hand and seal, this Twenty-first day of December, in
the year of our Lord One thousand eight hundred and sixty-
eight.
HENRY HIGHTON. (LS)