IMPROVEMENTS IN THE MANUFACTURE OF ALUM OR SULPHATE OF ALUMINA
Year: 1856

page_text: LETTERS PATENT to John Metcalf, of Newton Heath, near Manchester,
in the County of Lancaster, Manufacturing Chemist, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF ALUM OR SULPHATE OF ALUMINA,"
“IMPROVEMENTS IN THE MANUFACTURE OF ALUM OR SULPHATE OF ALUMI
PROVISIONAL SPECIFICATION left by the said John Metcalf at the
Office of the Commissioners of Patents, with his Petition, on the
13th December 1856.
I, JOHN METCALF, of Newton Heath, near Manchester, in the County of
Lancaster, Manufacturing Chemist, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF ALUM OR SULPHATE OF
ALUMINA," to bo as follows:-
The nature of my Invention consists in manufacturing alum or sulphate of
alumina from clay of any description whatever which contains alumina as a
base. That which I prefer at present to use for the purpose is known as
"china clay," which I take in the lump and wet state, as commonly brought
to the market for sale.
I take, say, one ton, and put it into a large cistern made of wood, stone,
lead, or other suitable material, and add thereto about four thousand and sixty
pounds of sulphuric acid, at 1.400 specific gravity, which mixture I agitate
until it becomes one homogeneous mass; I then run the same into a cylinder
or retort, such as are used for the manufacture of nitric or hydrochloric acids,

page_text: and heat it by fire or steam until the mixture becomes a solid dry mass, which
will then have acquired all the properties or nearly so of the finest alums
made. By this my improved process I dispense with the drying, crushing,
grinding, and calcining or wasting the clay before mixing it with the acid, by
which I effect a great saving of labour, time, and expense.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
.
by the said John Metcalf in the Great Seal Patent Office on the
12th June 1857.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOIN
METCALF, of Newton Heath, near Manchester, in the County of Lancaster,
Manufacturing Chemist, send greeting."
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirteenth day of December, in the year of our
Lord One thousand eight hundred and fifty-six, in the twentieth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said John Metcalf, Her special licence that I, the said John Metcalf, my
executors, administrators, and assigns, or such others as I, the said John
Metcalf, my executors, administrators, and assigns, should at any time agree.
with, and no others, from timo 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 MANO-
FACTURE OF ALUM OR SULPHATE OF ALUMINA," upon the condition, amongst
others, that I, the said John Metcalf, by an instrument in writing under my
hand and seal, 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 Metcalf, 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
(that is to say)
.
My Invention consists in manufacturing alum or sulphate of alumina from
clay of any description whatever which contains alumina as a base. That
which I prefer at present to use for the purpose is known as "china clay,"
which I take in the lump and wet state, as commonly brought to the market

page_text: for sale. I take, say, one ton, and put it into a large cistern made of wood,
stone, lead, or other suitable material, and add thereto about four thousand
and sixty pounds of sulphuric acid, at 1-400 specific gravity, which mixture I
agitate until it becomes one homogeneous mass; I then run the same into a
cylinder or retort, such as are used for the manufacture of nitric or hydro-
chloric acids, and heat it. fire or steam in any suitable furnace until the
mixture becomes a solid dry mass, which will then have acquired all the
properties or nearly so of the finest alums made. By this my improved
process I dispense with the drying, crushing, grinding, calcining, and washing
the clay before mixing it with the acid, by which I effect a great saying of
labour, time, and expense.
In order that my process may be thoroughly understood and easily performed,
I will describe the manner in which I perform the same.
First, I take, say, four hundred weight of china or other clay, put it into a
tub or cistern, and add thereto about thirty gallons of water; 1 agitate this
until it becomes thoroughly incorporated; I then add about four hundred and
twenty pounds of sulphuric acid of specific gravity 1.750 (more or less,
according to the quantity of alumina contained in the clay operated upon); I
mix these well together by agitation, and then run the said mixture of acid
and clay into a retort, vessel, or apparatus to dry the same, at a heat above
that of boiling water. The apparatus I prefer to use at present is a common
furnace; but it is of little consequence which way it is dried, so that a heat is
applied above that of boiling water. During the drying I keep the mass well
agitated, so that it will dry uniformly; and when so dried it is crude alum, or
sulphate of alumina. Or, I make a more pure alum or sulphate of alumina by
dissolving the crude alum in water, then letting it settle, I take the clear
liquior and boil it down until it becomes solid when cold; but, although this
alum is not completely pure, it is sufficiently so for many purposes.
I also make a more completely pure alum or sulphate of alumina from the
before-named crude sulphate of alumina by dissolving it in water and pre-
cipitating the iron contained therein with yellow or red prussiate of potash of
commerce; or I precipitate the iron with any other precipitant that will not
injuro the sulphate of alumina by so doing. That which I prefer to use, and
do now use, is yellow prussiate of potash of commerce. I ascertain tho
quantity of iron contained in the clay to be operated upon, I then add the
equivalent quantity of yellow prussiate of potash previously dissolved in water,
and taking the clear and puro sulphate of alumina liquor I boil the same
down until it forms a salt or solid mass when cold. I also make common
crystallized or rock alumn from the before-named crude alum, or sulphate of

page_text: alumina, by dissolving it in water and adding to the clear sulphate of alumina
liquor a saturated solution of sulphate of potash, sulphate of ammonia, or other
salts of the same bases, until the milkiness or cloudiness ceases to be produced
on adding more. I then dissolve the precipitate, evaporate it to the crystallizing
point, and then run it into the crystallizing vessels to crystallize, and in about
a week it will be ready to be taken out, broken into lumps, and sold.
Having thus described the nature of my said Invention, and the manner in
which the same is to be performed, I desire it to be distinctly understood that
I do not confine myself to the exact proportions or strengths of the aforesaid
materials or compounds; but I claim as my Invention, and which to the best
of my knowledge and belief has not been hitherto used within the realm,
Firstly, the making or manufacturing of crude alum or sulphate of alumina
by mixing china or other clay in a wet state with sulphuric acid, in contra-
distinction to using the said clay in a dry or calcined state, as heretofore
adopted.
Secondly, the making or manufacturing a pure alum or sulphato of alumina
from the beforo-named crude alum or sulphate of alumina.
Thirdly, the making or manufacturing a completely pure alum or sulphate of
alumina from the previously named crudo alum, or sulphate of alumina.
And, fourthly, the making rock alum from the crude alum, or sulphate of
alumina, aforesaid, as all such improvements or manufactures are herein
described.
In witness whereof, I, the said John Metcalf, have hereunto set my hand
and seal, this Ninth day of June, in the year of our Lord One thousand
eight hundred and fifty-seven.
JOHN METCALF. (L.S.)
Signed, sealed, and delivered by the within-
named John Metcalf, in the presence of
E. J. HUGHES, Patent Agent,
Manchester.