IMPROVE- MENTS IN THE MANUFACTURE OR PRODUCTION OF SULPHURIC ACID AND SULPHATES OF IRON AND ALUMINA
Year: 1855

page_text: LETTERS PATENT to Alexander Cuninghame, of Glasgow, in the County
of Lanark, North Britain, Iron Master, for the Invention of "IMPROVE-
MENTS IN THE MANUFACTURE OR PRODUCTION OF SULPHURIC ACID AND
SULPHATES OF IRON AND ALUMINA."
Sealed the 12th June 1855, and dated the 12th April 1855.
PROVISIONAL SPECIFICATION left by the said Alexander Cuninghame at
the Office of the Commissioners of Patents, with his Petition, on the
12th April 1855.
1, ALEXANDER CUNINGHAME, of Glasgow, in the County of Lanark, North
Britain, Iron Master, do hereby declare the nature of the said Invention of
"IMPROVEMENTS IN THE MANUFACTURE OR PRODUCTION OF SULPHURIC ACID AND
SULPHATES OF IRON AND ALUMINA" to be as follows, that is to say :-
This Invention relates to the manufacture or production of sulphuric acid
from alum schist, alum slate, and gentle slate, and what is technically known
in some parts of Scotland as "black stone;" that is, a harder species of alum
schist, commonly associated with ordinary alum schist. Any or all of those
mineral substances, as well as ironstone and coal, are available for application

page_text: in this process of manufacturing sulphuric acid. The raw material is first
ground or reduced to powder, and water is then added in quantity sufficient
to produce a plastic mass capable of being moulded into balls or brick-like
pieces in such form and size as shall be found convenient in the after practical
treatment to which the material is to be subjected. Such balls or masses
are moulded or produced either by hand, or, as is preferred, by machinery,
such, for example, as is ordinarily used in the manufacture of bricks for
building purposes. The balls or individual masses so made are placed in a
furnace, kiln, or other species of heating chamber, wherein they are subjected
to the action of a high temperature, or calcined; a small quantity of fuel
only is necessary in this calcining process, as after the balls or masses are
dry they usually burn of themselves, the bituminous matter and sulphur
contained in the schist having been rendered easy of combustion by the process
of disintegration or reduction already mentioned. During the combustion
of the balls, sulphurous acid vapours mixed with some sulphuric acid are
abundantly evolved from the treated materials, and these vapours are con-
ducted through stoneware tubes to leaden chambers, wherein they are to be
converted into sulphuric acid in the usual manner. When the kiln or
burning or burning chamber has "burned out," a result generally occurring
in a few days, the burnt balls or masses are removed and lixiviated for the
purpose of dissolving out the sulphates of iron and alumina, which matters
may then be employed for making copperas and alum; or if the oxidation
be incomplete, on removal from the burning chamber the masses may be
allowed to oxidise by the atmospheric action before being lixiviated. If the
heat employed has not been too high, copperas and alum may now be formed
in large quantities, particularly the copperas salt. On the other hand, if the
employed heat has been excessive, there will be evolved a greater proportion of
sulphurous and sulphuric acids and less of the copperas and alum salts as a
residuum. Steam may be employed, if necessary, for checking the heat,
should it at any time rise so high as to cause fusion of the materials. The
mineral substances herein-before referred to are used either singly or mixed,
as may be found most advisable in practice.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Alexander Cuninghame, in the Great Seal Patent Office on
the 10th October 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
CUNINGHAME, of Glasgow, in the County of Lanark, North Britain, Iron
Master, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twelfth day of April, in the year of our Lord One
thousand eight hundred and fifty-five, in the eighteenth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the said
Alexander Cuninghame, Her special license that I, the said Alexander Cuning-
hame, my executors, administrators, and assigns, or such others as I, the said
Alexander Cuninghame, my executors, administrators, or assigns, should at
any tine agree with, and no others, from time to time and at all times there-
after 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 OR PRODUCTION OF SULPHURIC ACID AND SULPHATES OF IRON
AND ALUMINA," upon the condition (amongst others) that I, the said Alexander
Cuninghame, by an instrument in writing under my hand and seal, should par-
ticularly 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 Cuninghame, do hereby
declare the nature of my said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement in writing, that is to say:-
My said Invention relates to the manufacture, obtainment, or production of
sulphuric acid and the sulphates of iron and alumina from or by the agency
of alum schist, alum slate, gentle slate, and what is technically known in some
parts of Scotland as "black stone," that is, a harder species of alum schist,
commonly associated or found lying in connection with ordinary alum schist
or gentle slate. All or any of these mineral substances, as well as such
ironstones and coals as contain sulphur, are applicable and available in
my system or process of manufacturing sulphuric acid. In proceeding to
manufacture sulphuric acid and the sulphates of iron and alumina, the raw

page_text: mineral, whether schist, black stone, or other of the mineral substances
herein-before mentioned, all or any of them, is ground or reduced to powder.
To this powder or disintegrated matter water is added in quantity sufficient
for the production of a plastic mass capable of being moulded into balls or
brick-like pieces of such form and dimensions as shall be found conveniently
manageable in the after practical manufacturing treatment to which the
material is to be subjected; or instead of adding water, the mineral substances
may be moulded or shaped without any liquid addition. Such balls or masses
are moulded or produced either by hand, or, as is preferred, by machinery,
such, for example, as is ordinarily used in the manufacture of bricks for
building purposes. The balls or individual masses so made are then deposited
in a furnace, kiln, or other species of heating apparatus or chamber, wherein
they are subjected to the action of a high temperature, or calcined. This
calcining process involves the expenditure of but a small quantity of fuel, as
after the balls or masses under treatment are dry, they usually burn of them-
selves; the bituminous matter and sulphur contained in the schist having been
rendered easy of combustion by the process of disintegration or reduction,
which I have already described. Under the application of heat in this way,
sulphur is driven off from the treated masses under the form of sulphuric and
sulphurous acid gases, which are abundantly evolved from them. These
vapours are conducted through stoneware or other tubes or thoroughfares to
the usual leaden chambers, wherein the gaseous matters are to be converted
into sulphuric acid in the ordinary manner. If it is intended to make sulphuric
acid only in this way, the heating process is carried on until the whole of the
contained sulphur is expelled; but if sulphate of iron or alumina is required,
the heat is checked or reduced at an anterior stage of the action, and the
treated bricks or masses are afterwards removed and lixiviated, when solutions
of these salts are obtained. The essential feature of my improvements consists
in the grinding or reducing of the alum schist or other mineral for the purpose
of converting it into masses, as herein-before mentioned, By this process of
conversion, such minerals as are comparatively poor in sulphur may be
rendered combustible, and applicable for the general purposes which I have
herein-before indicated.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I may observe, in conclusion, that I do not confine or restrict
myself to the precise details or arrangements which I have had occasion to
describe or refer to, as many variations may be made therefrom without
deviating from the principles or main features of my Invention; but what

page_text: I consider to be novel and original, and therefore claim as the Invention
secured to me by the herein-before in part recited Letters Patent, is,―
First, the general system and arrangements for the manufacture of sulphuric
acid and sulphates of iron and alumina, as herein-before described.
Second, the system or mode of manufacturing sulphuric acid and the
sulphates of iron and alumina, by grinding or reducing alum schist or other
minerals, as hercin-before described, and converting such reduced minerals
into masses for treatment by heat.
Third, the application and use of alum schist and other minerals converted
into bricks or masses of a similar character in the manufacture of sulphuric
acid and the sulphates of iron and alumina.
In witness whereof, I, the said Alexander Cuninghame, have hereunto set
my hand and seal, this Eighth day of October, One thousand eight
hundred and fifty-five.