IMPROVEMENTS IN THE MANUFACTURE OF ALUM
Year: 1842

page_text: TURNER'S SPECIFICATION.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILTON
GEORGE TURNER, of Gateshead, in the County of Durham, Doctor in
Philosophy, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Eighth day of October, in the sixth year of Her reign, did,
for Herself, Her heirs and successors, give and grant unto me, the said
Wilton George Turner, my exors, adñiors, and assigns, Her special licence,
full power, sole privilege and authority, that I, the said Wilton George Turner,
my exors, admiors, or assigns, or such others as I, the said Wilton George
Turner, my exors, admors, or assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term of
years therein expressed, should and lawfully might make, use, exercise, and
vend, within that part of the United Kingdom of Great Britain and Ireland
called England, the Dominion of Wales, and Town of Berwick-upon-Tweed,
my Invention of "IMPROVEMENTS IN THE MANUFACTURE OF ALUM;" in which
said Letters Patent is contained a proviso obliging me, the said Wilton George
Turner, by an instrument in writing under my hand and seal, particularly
to describe and ascertain the nature of my said Invention, and in what
manner the same is to be performed, and to cause the same to be enrolled in
Her Majesty's High Court of Chancery within six calendar months next and
immediately after the date of the said recited Letters Patent, as in and by the
same, reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
Wilton George Turner, do hereby declare that the nature of my said Inven-
tion consists in the manufacture of alum from felspar rocks, or any other rocks
or mineral substances containing salica and alumina sufficiently free from

page_text: other substances to be subjected to my process (which is performed by the.
aid of potash or of soda, as will be presently explained; and when I use
potash I call it a potash alum, and when I use soda I call it a soda alum).
I proceed (when desirous of making a potash alum) by fusing felspar or
other rock or mineral substance containing salica and alumina, with such salts
of potash as will yield when fused at a red or white heat a uniform glassy
substance. This glassy substance, if sufficient potash has been used, is
readily decomposed by water; the quantity of the salts of potash required will
in general be about twice the weight of the mineral substance used, although
under certain circumstances smaller quantities may answer.
The aqueous
solution contains silicate of potash, and the insoluble residuum is a light porous
substance similar in chemical composition to the mineral commonly called
aloeolite. This porous substance is decomposed by sulphuric acid, and forms
alum by the separation of its silica. If the above process be performed with
the salts of soda instead of potash, the light porous substances obtained will be
similar in chemical composition to the mineral known commonly as nepheline,
and its decomposition by sulphuric acid will give rise to the formation of a
soda alum. The manner in which my said Invention is to be performed is
as follows:-
If desirous of making a potash alum, the best substance to operate upon is
a potash feldspar. This felspar is ground in a common Edgestone mill to
the consistency of fine sand (a process which is much assisted by heating it to
redness and then plunging it in cold water); it is then mixed with its own
weight of sulphate of potash and placed in the upper part of the inclined bed
of a reverberatory furnace, represented in Figure A (being such a furnace as is
known in the potteries as a frit furnace), and which furnace has previously
been brought to a full white heat. When by the action of the heat a glass has
been produced, and is observed to flow down the inclined bed of the furnace, to
such glass is to be added gradually, at the lower end of the furnace, as much
carbonate of potash as was before used of sulphate of potash; and this process of
placing the mixture of felspar and sulphate of potash at the upper part of the bed
of the furnace is to be repeated, adding at the lower part of the bed gradually
and proportionally as the glass flows down from the upper part, the carbonate
of potash as before mentioned; this is continued until the sack of the furnace
is filled with the glass. This glass is then fit for the next process. The
preparation of the glass may also be effected in a reverberatory furnace with a
flat bed, and the facility of removing the glass from such a furnace is an
advantage. In this case no carbonate must be added to the mixture until
the sulphate of potash is observed to be completely decomposed. On boiling
in water the glass thus obtained the same quantity of potash as was added to

page_text: the felspar and two thirds of the silica contained in the felspar are dis-
solved, while the remaining one third of the silica and the alumina, and
an equal quantity of potash as the felspar originally contained are left,
in the form of a light porous substance, similar in chemical composition
to the mineral commonly called alcolite. This porous substance is care-
fully separated from the said solution and washed with water until freed
from the silicate of potash, then placed in an open leaden cistern or boiler,
and boiled with dilute sulphuric acid of the specific gravity 1.2 (one and two
tenths). This acid will contain about the quantity of water required for the
solution and chrystallization of the alum produced by the decomposition of
the aleolite. The quantity of the dilute sulphuric acid must be such as
will contain about one hundred and sixty pounds of dry sulphuric acid for
every two hundred and eighty-five pounds of felspar rock (if that. rock be
used), and in like proportion to the silica and alumina contained in the
substance if any other substance be used. As it is important that the alum
solution thus obtained should not contain an excess of acid, I would recom-
mend that only four-fifths of the proposed quantity of dilute sulphuric acid
should be used in the first operation, which will leave a portion of the alœolite
undecomposed, but by acting upon this undecomposed portion after the
solution has been drawn off with the full quantity of dilute acid to be used
in the next operation, it will be completely decomposed, and the alum thus
formed becomes part of the next batch; in this way a neutral solution of
alum is obtained at each process. The boiling solution. after the sediment
subsides is drawn into coolers, such as are commonly used for the chrystalliza-
tion of alum, here about four fifths of the alum held in solution will form
iuto chrystals. The mother liquor is drawn off and leaves the alum which
is now in form to undergo the usual process of washing and roaching.
The mother liquor from the coolers is boiled in any convenient boiler to
dryness, in order to render the silica it contains insoluble; this residuum is
boiled either in water or in the mother liquor, from the roaching tubs, so as
to dissolve the alum it contains, and the process of chrystallization repeated.
Had the above process been performed with the salts of soda, instead of potash,
a soda alum would have been formed; for this purpose the soda felspar or
albite should be selected. The potash or soda (as the case may be) contained
in the liquor drawn as aforesaid from the alcolite (or nepheline, which is
formed when soda is used) may be recovered by either of the following
processes:-The strong solutions, which are obtained about the specific gravity
1-2 (one two-tenths), are placed in any convenient vessel in which a stream
of carbonic acid gas obtained in any convenient method may be driven through
them; the carbonic acid becomes absorbed and the solution assumes the form of

page_text: a gelatinous mass; this mass consists of carbonate of potash or soda and hydrate
of silica. On drying this mass in a furnace, which must never be allowed to rise
to red heat, even in the dark, the silica loses its water and becomes insoluble; the
potash or soda may then be separated from it in the form of a sesquicarbonate
of potash or soda by solution and evaporation to dryness. The other process,
which under most circumstances will be found more economical and conve-
nient, is to allow the boiling solution of silicate of potash or soda to filter
through a bed of caustic lime, when it will be found that the lime has
combined with the silica and a caustic potash or soda ley obtained. This
process may be conveniently conducted in an apparatus similar to that used by
soap makers for the preparation of their caustic leys. The potash or soda
may then be readily obtained as caustic potash or soda or as carbonate by
the known processes used in making soda. The weak solutions of silicate of
potash or soda are used to decompose another portion of the glassy substance.
Now I do not claim as new or as my Invention any particular form of
vessel or apparatus in which or with which my operations may be conducted;
nor do I claim any particular proportions in which the alkaline salts may be
used; but I claim as new and as my Invention the improvements aforesaid,
and the production of substances similar to alcolite and nepheline artificially,
by the decomposition by water of the glassy substances produced by the fusing
of felspar as aforesaid, or other mineral substances containing silica and
alumina with salts of potash and soda as aforesaid, and the use and appli-
cation of such artificial alcolite and nepheline in the production and manu-
facture of alum as aforesaid.
I also claim the process as above described for separating the alkalies
from silica by means of caustic lime.
And such my Invention being, to the best of my knowledge and belief,
entirely new and never before used in that part of Her Majesty's United
Kingdom of Great Britain and Ireland called England, Her Dominion of
Wales, and Town of Berwick-upon-Tweed, I do hereby declare this to be my
Specification of the said Invention.
In witness whereof, I, the said Wilton George Turner, have hereunto
set my hand and seal, the Seventh day of April, One thousand eight
hundred and forty-three.
WILTON GEORGE (L.S.) TURNER.
Signed, sealed, and delivered (being first
duly stamped) in the presence of
W* PRINGLE,
3, King's Road, Bedford Row,
London.

page_text: AND BE IT REMEMBERED, that on the Seventh day of April, in the
year of our Lord 1843, the aforesaid Wilton George Turner came before our
said Lady the Queen in Her Chancery, and acknowledged the Specification
aforesaid, and all and every thing therein contained and specified, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute made for that purpose.
Enrolled the Eighth day of April, in the year of our Lord One thousand
eight hundred and forty-three.