IMPROVEMENTS IN THE PREPARATION OF DECOLOURISING MATERIALS."
Year: 1855

page_text: LETTERS PATENT to John Stenhouse, of 15, Upper Barnsbury Street,
Islington, for the Invention of "IMPROVEMENTS IN THE PREPARATION OF
DECOLOURISING MATERIALS."
PROVISIONAL SPECIFICATION left. by the said John Stenhouse at the
Office of the Commissioners of Patents, with, his Petition, on the 13th
October 1855.
I, JOHN STENHOUSE, of 15, Upper Barnsbury Street, Islington, do hereby
declare the nature of the Invention for "IMPROVEMENTS IN THE PREPARATION OF
DECOLOURISING MATERIALS" to be as follows:-
My Invention consists in treating vegetable charcoal so as to render it
capable of being employed as a decolourising agent.
This I effect by introducing certain substances, such as oxide of iron and
alumina, or phosphate of lime, in a state of solution, into the mass or substance
of vegetable charcoal, and then rendering these substances insoluble within
the pores of the charcoal. For this purpose I employ the soluble salts or
solutions of these and similar substances. The charcoal is heated with the
solution of these substances till the air contained in its pores is expelled and

page_text: the charcoal saturated with .the solution. The charcoal is then dried and
heated to redness in close vessels till the water and acid contained in it are
expelled. Vegetable charcoal so treated may be used for the purpose of
decolorising syrups and other coloured solutions::
SPECIFICATION in pursuance of the conditions of the. Letters Patent, filed
by. the said John Stenhouse in the Great Seal Patent Office on the
31st March 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
STENHOUSE, of 15, Upper Barnsbury Street, Islington, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of October, in the year of our Lord
One thousand eight hundred and fifty-five, in the nineteenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said John Stenhouse, Her special licence that I; the said John Stenhouse,
my executors, administrators, and assigns, or such others as I, the said John
Stenhouse, 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 "IMPROVEMENTS IN THE PREPARATION
OF DECOLORIZING MATERIALS," upon the condition (amongst others) that I, the
said John Stenhouse, 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 John Stenhouse, do hereby, declare
the nature of the 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 thereof, that is to say:-
My Invention consists in treating vegetable charcoal so as to render it
capable of being employed as a decolourizing agent. This I effect by intro-
ducing certain substances, such as oxide of iron and alumina, or phosphate of
lime, in a state of solution, into the mass or substance of vegetable charcoal,
"

page_text: and then rendering these substances insoluble within the pores of the charcoal.
For this purpose I employ the soluble salts of solutions of these and similar
substances. The charcoal is heated with the solution of these substances
till the air contained in its pores is expelled and the charcoal saturated with
the solution. The charcoal is then dried and heated to redness in close
vessels till the water and acid contained in it are expelled. Vegetable char-
coal so treated may be used for the purpose of decolorizing syrups and other
coloured solutions.
Having thus stated the nature of my said Invention, I will proceed to
describe more fully the manner of performing the same.
My Invention as above stated has for its object the manufacture of vegetable
charcoal in combination with other substances, so as to render the combined
product capable of being employed more beneficially as a decolourizing agent,
and suitable for being used as a substitute for animal charcoal or bone black.
I do not confine myself to the particular manner herein described, as the
details of manufacture may be varied without departing from my Invention;
but the following is the manner I carry out my Invention, and I believe it to
be the best for the purpose. The substances used in obtaining the combina-
tion are vegetable charcoal, phosphate of lime, alumina, and oxide of iron, and
I obtain a product consisting of vegetable charcoal, saturated or combined
with the other substances in an insoluble state. For this purpose I employ
vegetable charcoal, and solutions of phosphate of lime, solutions of alumina,
and oxide of iron. The charcoal is boiled in the solutions of the substances
above mentioned till the air contained in its pores is expelled and the
charcoal saturated with the solution. The charcoal is then dried and heated
to redness in close vessels. By operating in this way I obtain a variety of
decolorizing materials, according to the mode of manufacturing, which I will
now proceed more particularly to describe. The first of these is vegetable
charcoal impregnated with phosphate of lime. To effect this, I take vegetable
charcoal, either in the state of powder or in a granular state, similar to the
animal charcoal usually employed by sugar refiners. This charcoal is boiled
in any suitable vessels' with a concentrated' solution of phosphate of lime in
hydrochloric acid, till the air contained in the pores of the charcoal is expelled,
and the charcoal saturated with the phosphate of lime solution. The phos-
phate of lime may be obtained from any of the sources which are well known.
I combine, according to circumstances, variable quantities' of phosphate of
lime with vegetable charcoal, but the quantity which I have found most con-
venient is about seven and a half parts by weight of phosphate of lime
dissolved in twenty parts of commercial hydrochloric acid, and diluted with

page_text: about forty parts of water for every ninety-two and a half parts by weight of
vegetable charcoal; and I digest or boil the charcoal therein till the air in the
charcoal ceases to come off. When the solution has thoroughly penetrated
the pores of the charcoal, the whole compound is dried and heated to a red
heat throughout in close vessels, by which the water and acid contained in it
are expelled. The product is then ready for use. Another decolourizing
material is formed by uniting alumina with vegetable charcoal. This I effect
as follows:-Vegetable charcoal, either in fine or coarse powder, is digested or
boiled with a solution of sulphate or hydrochlorate of alumina, or aqueous
chloride of aluminum, as the latter salt is sometimes called, till the pores of
the charcoal are thoroughly penetrated by the solutions. The charcoal is
then dried and heated to redness in close vessels till all the acid and water
are expelled. The compound is then ready for use. The amount of alumina
which is introduced into the charcoal may be varied, but I usually operate so
as to unite the charcoal with about seven and a half per cent. of anhydrous
alumina, though I do not restrict myself to this quantity, for very efficient
charcoal may be made with greater or smaller proportions of alumina.
The alumina I prefer to employ for impregnating the charcoal is obtained
by using the well-known sulphate of alumina, made by digesting the purest
kinds of pipe clay after gentle calcination in pretty strong sulphuric acid.
When a solution of this salt is sufficiently concentrated by evaporation, it
solidifies on cooling, and usually contains about fourteen per cent. of alumina.
If fifty-four parts of this salt are dissolved in water and digested with ninety-
two and a half parts of charcoal, on heating to redness in close vessels
aluminized charcoal is produced, containing about seven and a half per cent."
of alumina.
A more economical method of obtaining .a like product is by employing a
solution of sulphate of alumina of known strength, so as to incorporate the
charcoal with the desired amount of alumina. I have found that in place of
using phosphate of lime and alumina separately, as above described, a mixture
of phosphate of lime and alumina may be employed. This is effected by
dissolving the phosphate of lime in hydrochloric acid, and adding to the solu-
tion hydrochlorate of alumina. The charcoal after being digested with the
mixed solution is dried and heated to redness in close vessels, in 'the way
already described. I also combine vegetable charcoal with oxide of iron by
digesting or boiling the charcoal with the soluble proto or persalts of iron,
such, for instance, as the sulphate (copperas) or the persulphate of the oxide
of that metal. The charcoal manufactured in this way possesses considerable
decolourizing power, but it is found that much of the iron is reduced to the

page_text: state of protoxide by contact with the charcoal at a high temperature, and
that a portion of it is apt to dissolve in solutions containing acid, and there-
fore this agent should not be used when acid is present, but only in other
cases where acid is not present. In speaking above of the use of close vessels,
I mean, as is well understood, vessels which will admit of the passage away of
the volatile products, and yet exclude the outer atmosphere.
In witness whereof, I, the said John Stenhouse, have hereunto set my
hand and seal, this 29th day of March, in the year of our Lord
One thousand eight hundred and fifty-six.
Witness,
RICHARD VINE TUSON.
JOHN STENHOUSE. (L.S.)