IMPROVEMENTS IN THE MANUFACTURE OF ALUM
Year: 1877

page_text: LETTERS PATENT to Peter Spence, of Manchester, in the County of Lancaster,
Manufacturing Chemist, and Francis Mudie Spence, of the same Place, Manu-
facturing Chemist, for the Invention of" IMPROVEMENTS IN THE MANUFACTURE
OF ALUM."
Sealed the 29th December 1877, and dated the 6th July 1877.
PROVISIONAL SPECIFICATION left by the said Peter Spence and Francis
Mudie Spence at the Office of the Commissioners of Patents on the 6th July
1877.
PETER SPENCE, of Manchester, in the County of Lancaster, Manufacturing
Chemist, and FRANCIS MUDIE SPENCE, of the same Place, Manufacturing Chemist.
"IMPROVEMENTS IN THE MANUFACTURE OF ALUM."
It is well known that alum may be made from the commercial sulphate of
alumina, known as cake alum, aluminous cake, and alumino-ferric cake. These
compounds of alumina and sulphuric acid contain a small proportion of free sulphuric
acid, and also some sulphate. of oxide of iron, but nearly all the sulphuric acid is in
combination with alumina; and our Invention has for its object the conversion of
all the alumina of the said compounds into alum by the use of chloride of potassium.
To effect this we add to the solution of any of those aluminous compounds, or to the
sulphuric acid used in their production, as much of a soluble sulphate, say, of soda
or magnesia (or even iron, but not by preference) as will convert all the requisite
quantity of chloride of potassium into sulphate of potash, so as to allow all the
sulphate of alumina to be converted into alum. This, in practice, will require as
much of any of these salts as, when added to the solution of sulphate of alumina,
will represent about one-fourth of all the sulphuric acid present.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Peter Spence and Francis Mudie. Spence in the Great Seal
Patent Office on the 5th January 1878.
PETER SPENCE, of Manchester, in the County of Lancaster, Manufacturing
Chemist, and FRANCIS MUDIE SPENCE, of the same Place, Manufacturing Chemist.
"IMPROVEMENTS IN THE MANUFACTURE OF ALUM."
It is well known that alum may be made from the commercial sulphates of
alumina, known as cake alum, aluminous cake, and alumino-ferric cake. These
compounds of alumina and sulphuric acid contain a small proportion of free sulphuric
acid, and also some sulphate of oxide of iron, but nearly all the said acid is in com-
bination with the alumina; and our Invention has for its object the conversion of
all, or substantially all, of the alumina of the said compounds into alum, and this
we effect by the use of chloride of potassium, other agents being also employed.
In carrying out our Invention, by one method we first ascertain, by ordinary
analysis, the quantity of alumina present in the particular description of cake to be
used, and the relative quantity of sulphuric acid, calculating the additional acid
required to combine with an added quantity of potassium in the form of chloride
necessary for the conversion of the alumina into alum. We now add as much
sulphate of soda or other soluble sulphate, as, for instance, that of magnesia (or of
iron, but not by preference) as will yield, when decomposed, the required amount
of acid to combine with the potassium.
The mixture being then dissolved, a decomposition takes place affording a solution
of alum, which may be crystallized therefrom in the ordinary manner, a chloride
produced by the double decomposition remaining in solution. Or if we desire to
produce alum from a solution of sulphate of alumina, made from any comparatively
pure aluminous compound, such as calcined china clay or from bauxite, when there
is but little, if any, other base to combine with the sulphuric acid, and when the
solutions would therefore be a nearly pure sulphate of alumina, then we add to
the said solution, or to the acid before it has acted on the aluminous compound, as
much sulphate as aforesaid as will afford sulphuric acid to the potassium of the
chloride thereof as will be required for producing alum from the solution, and by
these methods we get all or nearly all the sulphate of alumina converted into
alum.
Having thus described and ascertained the nature of our said Invention and the
manner in which the same is to be performed, I desire it to be understood that we
claim as secured to us under the above in part recited Letters Patent and for the
purpose above set forth, submitting such compounds of alumina as above mentioned
to the action of chloride of potassium and a soluble sulphate.
In witness whereof, I, the said Francis Mudie Spence, have hereunto set my
hand and seal, this Fourth day of January, in the year of our Lord One
thousand eight hundred and seventy-eight.
F. M. SPENCE. (L.S.)