IMPROVEMENTS IN THE TREATMENT OF CERTAIN SALTS, COMMONLY CALLED ALUMS, TO OBTAIN PRODUCTS THEREFROM
Year: 1855

page_text: LETTERS PATENT to Edward Frankland, of Owen's College, Manchester,
in the County of Lancaster, for the Invention of "IMPROVEMENTS IN THE
TREATMENT OF CERTAIN SALTS, COMMONLY CALLED ALUMS, TO OBTAIN PRODUCTS
THEREFROM."
Sealed the 23rd October 1855, and dated the 25th April 1855.
PROVISIONAL SPECIFICATION left by the said Edward Frankland at the
Office of the Commissioners of Patents, with his Petition, on the 25th
April 1855.
I, EDWARD FRANKLAND, of Owen's College, Manchester, in the County of
Lancaster, do hereby declare the nature of the Invention for "IMPROVEMENTS
IN THE TREATMENT OF CERTAIN SALTS, COMMONLY CALLED ALUMS, TO OBTAIN PRODUCTS
THEREPROM," to be as follows:-
My improvements consist in the treatment of certain salts, commonly called
alums, in such a manner as to obtain in a separate state the two constituent
salts of which such alums are composed, thus avoiding the loss of the alkaline
constituent of the alums, which is now commonly thrown away and wasted
in most of the operations in which alums are used. I effect this separation
of the constituent salts by adding certain chemical substances or solutions to
a solution of alum, so as to precipitate from the alum its alumina, either as
www
IN THE TREATMENT OF CERTAIN SALTS, COMMONLY CALLED ALUMS, TO OBTAIN PRODUCTS
THEREFROM," to be as follows:-
My improvements consist in the treatment of certain salts, commonly called
alums, in such a manner as to obtain in a separate state the two constituent
salts of which such alums are composed, thus avoiding the loss of the alkaline
constituent of the alums, which is now commonly thrown away and wasted
in most of the operations in which alums are used. I effect this separation
of the constituent salts by adding certain chemical substances or solutions to
a solution of alum, so as to precipitate from the alum its alumina, either as

page_text: hydrated oxide of alumina or as a sub-salt of alumina, and so as to leave in
solution the other constituent of the alum, namely, the alkaline sulphate.
For this purpose I prefer to use ammonia or carbonate of ammonia either in
the state of vapour or solution, although other alkaline substances may be
employed. I also prefer to precipitate the alumina as a sub-salt of alumina,
whereby I require a much smaller proportion of the precipitant. When the
precipitation has been effected, I separate the alumina or sub-salt of alumina
from the liquid by filtration in the usual manner, and afterwards convert such
alumina or sub-salt of alumina into a soluble salt of alumina by adding to
it the requisite quantity of sulphuric acid, acetic acid, or other acid capable of
forming a soluble salt with alumina. Thus, by applying my improvements to
ammonia alumn I obtain as final products, first, a soluble simple salt of alumina,
and secondly, crystallized sulphate of ammonia; and by applying my process
to potash alum I obtain, firstly, a soluble simple salt of alumina, and secondly,
a mixture of sulphate of potash and sulphate of ammonia, which two last-
named salts may be separated by crystallization.
My improvements are also equally applicable to alums which are only
partially manufactured, provided such partially manufactured alums, are suffi-
ciently free from iron to yield a simple salt of alumina sufficiently pure for the
purposes to which alums are commonly applied.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Edward Frankland in the Great Seal: Patent Office on the
24th October 1855.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, EDWARD
FRANKLAND, of Owen's College, Manchester, in the County of Lancaster,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fifth 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
Edward Frankland, Her special licence that I, the said Edward Frankland,
my executors, administrators, and assigns, or such others as I, the said
Edward Frankland, 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,

page_text: 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 TREATMENT OF CERTAIN SALTS, COMMONLY CALLED ALUMS, TO OBTAIN PRODUCTS
THEREFROM," upon the condition (amongst others) that I, the said Edward
Frankland, 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 Edward Frankland, 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) :-
Whereas the chief object of the usual process for the manufacture of
alums is the production of a soluble salt of alumina as free from iron and
other impurities as possible; and whereas in order to attain this object it is
necessary to combine the salt of alumina with certain alkaline salts, namely,
either with the sulphate of ammonia or with the sulphate of potash, which
alkaline salts are commonly wasted and thrown away, being useless in the
processes to which the alums are generally applied: Now, my improvements
consist in the separation of those alkaline salts from the alums, by which
means such alkaline salts are conserved and utilised; and I effect this object
by dissolving the alums in water and then throwing down the alumina con-
tained therein either as pure alumina or as sub-sulphate of alumina. By the
addition of a certain quantity of alkali or carbonated alkali I separate the
precipitated alumina or sub-sulphate of alumina, which I will hereafter call
the aluminous precipitate, from the liquor in the usual manner by filtration,
and I then convert the aluminous precipitate thus obtained into neutral
sulphate of alumina by adding the requisite quantity of sulphuric acid. The
liquor separated from the aluminous precipitate contains the alkaline sulphates,
previously forming a component part of the alums, together with an additional
quantity of alkaline sulphate which has been formed in the above separation
of the aluminous precipitate, which. alkaline sulphates can be obtained from
the liquor in the usual manner by evaporation and crystallization. Now, my
Invention is applicable both to potash alum and ammonia alum, but it can be
applied with the greatest advantage to ammonia alum, and I will therefore
first describe the processes I prefer to employ in the application of my Invention
to ammonia alum.
I first take a convenient quantity of ammonia alum, and put it into three

page_text: times its weight of water, and dissolve it by free steam; I then produce a
current of steam charged with ammoniacal gas in the usual manner by passing
free steam into a mixture of lime and the ammoniacal liquor of gas works
contained in a close vessel; from this vessel I conduct the ammoniacal steam
into the solution of alum by means of a leaden pipe, and continue the current
until the whole of the alumina is precipitated, which is known by the alum
liquor exhibiting an alkaline reaction with test papers. The absorption of the
ammoniacal steam by the alum liquor may be facilitated, if necessary, by
frequent agitation of the alum liquor. When all the alumina has been thus
precipitated, I run the ammoniated alum liquor upon a filter which retains
the aluminous precipitate whilst the solution of sulphate of ammonia runs
through, and I free the aluminous precipitate from the last portions of sul-
phate of ammonia solution by repeatedly washing it upon the filter with clear
water. The filter I use consists of a shallow rectangular wooden vessel with
a false bottom, perforated with holes, and over which a piece of coarse calico
is stretched. When the aluminous precipitate has been thus freed as con-
pletely as possible from the sulphate of ammonia solution, I transfer it to an
open iron boiler lined with lead, and I then add to it sulphuric acid of the
strength of one hundred degrees Twaddle in sufficient quantity to dissolve it;
for this purpose I find that the aluminous precipitate from one ton of alum
requires about ten hundredweight of sulphuric acid of this strength. When
the solution of the aluminous precipitate has been effected, I apply heat to the
boiler and continue the liquor in ebullition until it becomes so concentrated as
to solidify on cooling, which I ascertain by taking out a sample of the liquid
from time to time; I then allow the contents of the boiler to cool, and the
product is sulphate of alumina in a marketable condition. I then evaporate
and crystallise in the usual manner the sulphate of ammonia liquor, separated
from the aluminous precipitate by filtration, as above described, and I thus
obtain marketable sulphate of ammonia.
In applying my Invention to potash alum, I put this alum into six times
its weight of water, and then use exactly the same process as that just
described for ammonia alum, and obtain in like manner marketable sulphate
of alumina; but in this case the solution of alkaline sulphate separated from
the aluminous precipitate by filtration consists of a mixture of sulphate of
potash and sulphate of ammonia. These two salts can be separated from each
other by crystallisation, or the solution can be evaporated to dryness, and the
mixed sulphates of potash and ammonia can be used in the manufacture of
artificial manures, or for other purposes to which such a mixture of sulphates
may be applicable.

page_text: I have now described the processes which I prefer to use in applying my
Invention, but the same effect can be produced by various modifications of
these processes; I do not, therefore, confine myself to the details given above;
and I hereby declare that I claim as my Invention, the separation of the
aluminous constituent from the alkaline constituent of completely or partially
manufactured alums by the application of ammonia or carbonate of ammonia,
or of a caustic or carbonated alkali, so as to conserve and utilise the alkaline
constituent of such alums; but I do not claim the manufacture of sulphate
of alumina nor of alkaline sulphates by other methods.
In witness whereof, I, the said Edward Frankland, have hereunto set
my hand and seal, this Eighteenth day of October, in the year of our
Lord One thousand eight hundred and fifty-five.
Witness,
EDWARD FRANKLAND. (L.S.)
JAMES HOLME NICHOLSON,
Clerk & Librarian,
Owen's College, Manchester.