IMPROVEMENTS IN THE MANUFACTURE ⚫ OF SULPHATE OF ALUMINA
Year: 1861

page_text: LETTERS PATENT to Alexander Angus Croll, of Coleman Street, in the
City of London, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE
⚫ OF SULPHATE OF ALUMINA."
Sealed the 3rd December 1861, and dated the 7th June 1861.
PROVISIONAL SPECIFICATION left by the said Alexander Angus Croll
at the Office of the Commissioners of Patents, with his Petition, on the
7th June 1861.
I, ALEXANDER ANGUS CROLL, of Coleman Street, in the City of London,
Engineer, do hereby declare the nature of the said Invention for "IMPROVE
MENTS IN THE MANUFACTURE OF SULPHATE OF ALUMINA," to be as follows:-
By the method generally adopted in the manufacture of sulphate of alumina
from shale and other aluminous matters, the material to be operated upon is
together with the sulphuric acid (oil of vitriol) in a comparatively weak
solution placed in a suitable vessel, and then heat is applied to them and
maintained until the desired solution of sulphate of alumina is attained, by
which considerable time is occupied.

page_text: By my improvements I first place the shale or other aluminous matter to
be operated upon, by preference in a dry state, and heated in a suitable vessel,
and then cause to flow upon it the sulphuric acid (oil of vitriol), which has
also been previously heated, by which the desired solution of sulphate of
alumina is very quickly obtained adapted to be used in the manufacture 5
of alum.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Angus Croll in the Great Seal Patent Office
on the 7th December 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
ANOUS CROLL, of Coleman Street, in the City of London, Engineer, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Seventh day of June, in the year of our Lord
One thousand eight hundred and sixty-one, in the twenty-fourth-year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Alexander Angus Croll, Her special licence that I the said Alexander
Angus Croll, my executors, administrators, and assigns, or such others
as I, the said Alexander Angus Croll, 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 MANUFACTURE OF SULPHATE OF ALUMINA," upon the
condition (amongst others) that I, the said Alexander Angus Croll,
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 Alexander Angus Croll, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say :-

page_text: By the method generally adopted in the manufacture of sulphate of alumina
from shale and other aluminous matters the material to be operated upon is,
together with the sulphuric acid (oil of vitriol) in a comparatively weak
solution, placed in a suitable vessel, and then heat is: applied to them and
maintained until the desired solution of sulphate of alumina is attained, by
which considerable time is occupied.
By my improvements, supposing the object to be the production of sulphate
of alumina in the form of cake to be used in the manufacture of paper or
otherwise, the shalo or other aluminous matter, as china clay, to be operated
upon having been roasted, as is well understood, is placed after being finely
powdered in a suitable vessel, by preference in a dry state, and also, by
preference, is subjected to heat till it bas attained a temperature of about 300
degrees Fahrenheit, and I then cause to flow upon it, whilst thus-heated, the
sulphuric acid (oil of vitriol) of about 1-700 strength, and which has also been
previously heated to a temperature of about 300 degrees Fahrenheit, and in
the proportions of about 20 parts by weight of sulphuric acid to about 20 parts
by weight of aluminous matter. The proportional quantity of acid required
depending upon the amount of alumina, apart from foreign matter in the
aluminous matter employed, and which is readily ascertained by the usual
tests. These matters must be intimately mixed. By these means a solution
of sulphate of alumina will be very quickly obtained. I find it better to retain
the heat in the mass until the temperaturo is reduced to about 150 degrees
Fahrenheit; for which reason I have found the operation is best conducted
upon masses of not less than 5 tons, which may then be cut into the desired
forms and sizes of cakes.
г
When the sulphate of alumina to be obtained is required for use in the
manufacture of alum, the previously described process may be pursued, or the
following, that is to say, shale, after being roasted in the ordinary way, and
before being subjected to the action of the sulphuric acid, is moistened with
water at a temperature of about 212 degrees Fahrenheit, and the heat of it
generally is raised to about that temperature, when it is subjected to the
action of sulphuric acid, of about the strength, temperature, and relative pro-
portions above stated. The mass being intimately mixed, it is better not to be
disturbed until the temperature has been slowly reduced to about 200 degrees
Fahrenheit; after which the sulphate of alumina may be dissolved out by
boiling water for the manufacture of alum.
Having thus described the nature of my said Invention, and the means I
adopt in carrying the same into effect, I would have it understood that what I

page_text: claim is, the manufacture of sulphate of alumina, in manner substantially as
explained.
In witness whereof, I, the said Alexander Angus Croll, have hereunto
set my hand and seal, this Seventh day of December, in the year of
our Lord One thousand eight hundred and sixty-one.
Witness,
WILLIAM BROOKES,
73, Chancery Lane, London,
Patent Agent.
ALEX³. CROLL. (L.S.)