IMPROVEMENTS IN THE MANUFACTURE OF COPPERAS AND ALUM
Year: 1845

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PETER
SPENCE, of Burgh, in the County of Cumberland, Chemist, send greeting.
year of
WHEREAS ller present most Excellent Majesty Queen Victoria, by Her
Royal Letters Patent under the Great Seal of Great Britain, bearing date a
Westminster, the Twenty-seventh day of November, in the ninth
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said Peter Spence, my exors, adñiors, and assigns, Her especial licence,
full power, sole privilege and authority, that I, the said Peter Spence, my
exors, admors, and assigns, or such others as I, the said Peter Spence, my
exors, admors, or assigns, should at any time agree with, and no others, from
time to time and at all times during the term of years therein expressed,
should and lawfully might make, usc, exercise, and vend, within England,
Wales, and the Town of Berwick-upon-Tweed, my. Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF COPPERAS AND ALUM;" in which said Letters Patent is
contained a proviso that I, the said Peter Spence, shall cause a particular
description of the nature of the said Invention, and in what manner the
same is to be performed, to be inrolled in Her said Majesty's High Court of
Chancery within six calendar months next and immediately after the date of
the said in part 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
Peter Spence, do hereby declare that the nature of my said Invention, and

page_text: the manner in which the same is to be performed, are fully described and
ascertained in and by the following, statement: thereof, that is to say :-
My Invention relates,-.
First, to improvements in the manufacture of copperas; and,
Secondly, to improvements in the manufacture of alum.
And in order that my Invention may be fully understood and readily carried
into effect, I will proceed to describe the means pursued by me. It is well
known in manufacturing copperas from iron pyrites according to the means
heretofore resorted to, that the pyrites is spread out in what are called beds,
in order that the atmosphere may act thereon, and the rain falling on such
beds washes out the soluble product which flows into tanks. The liquor thus
obtained is first rendered neutral by scrap iron, and then concentrated by heat,
and when at a proper density it is allowed to crystallize.
Now the first part of my Invention consists of treating a product of similar
pyrites (obtained by burning) with dilute sulphuric acid, and, thus obtaining
a neutral solution of copperas of a proper strength for crystallization, by
which a considerable saving will be effected. The product of pyrites used in
carrying out my Invention I prefer to obtain when burning; the description
of pyrites (heretofore used in the manufacture of copperas) for manufacturing
sulphuric acid therefrom, as is well understood, and the product required by me
for this part of my Invention, is, in fact, the refuse matter resulting from such
manufacture; at the same time I would state, that the product from these
pyrites obtained by burning, whether for making sulphuric acid or otherwise,
is what I employ for carrying out this part of my Invention; and I would
state, that in burning the pyrites when manufacturing sulphuric acid I prefer
that the burning should proceed rapidly with a free admission of air; and so
as to produce clinkers; and this product I subject to the action of diluted
sulphuric acid of about 1.2 specific gravity in vessels lined with lead. The
specific gravity above mentioned I find to produce a neutral solution of
copperas of a proper strength for crystallization, thus avoiding the necessity
for any process of evaporating the liquor; and I keep up a temperature of
from one hundred and sixty degrees to two hundred degrees of Fahrenheit, by
means of steam pipes or by other convenient means; the diluted sulphuric
acid covering the materials, and the temperature is maintained for ten or
twelve hours, and I avoid allowing the liquor to boil. At the time mentioned
the sulphuric acid will be neutralized, and the solution of copperas will be
about 1.35 to 1.4 specific gravity, and the same is run off by a syphon into
coolers of stone or other material lined with lead, wherein the copperas
will crystallize; and this latter part of the manufacture is the same as

page_text: .
that heretofore practised. After having drawn off the liquor from the
materials under process, I apply a fresh quantity of diluted sulphuric acid to
the materials, and heat and run off as before; and I am guided in the time
of digesting the materials with the diluted acid by keeping up that process
till the solution of copperas is at the specific gravity above mentioned, the
time required being greater as the matters under process become more spent;
and I repeat the application of diluted acid as many as ten or twelve times,
after which I consider the matters so spent that it will not compensate for
further treatment with acid. And I would state, that in the progress of
working I use the motlier liquors for the purpose of diluting sulphuric acid;
and the refuse matters, after having been thus treated successively with diluted
sulphuric acid, will be found to contain free sulphur. I therefore, mix such
matters with pyrites; when burning, to obtain sulphuric acid.
I will now proceed to describe the second part of my Invention. It is
well known that when making alum from clay or other aluminous materials,
usually called the artificial process, it has been usual to calcine such matters,
and to reduce them to' powder, and then to use diluted sulphuric acid, and
stir the same with the powder, so as to obtain a rapid action of the sulphuric
acid on the aluminȧ, the result being a thick pasty mass, through which the
sulphate of alumina is diffused, when successive quantities of water are
applied and stirred up with the matter, and the waters so applied are successively
run off, the liquor being allowed to settle before running off or afterwards.
The liquors thus obtained being in a very diluted state require to be evapo-
rated. Now this part of my Invention consists of subjecting shales or
aluminous matters, after they have been calcined, to repeated digestings with
diluted sulphuric acid, by which I am enabled to obtain clear liquor of a
proper strength for chrystallization without evaporation, and I avoid tho
repeated washings of the material with water after the acid has been
applied, which washings have heretofore been the means resorted to, in
order to obtain from the materials the sulphate of alumina, and which
liquors so obtained have, as before remarked, required much evaporation to
reduce them to the proper density. In carrying out this part of my Inven-
tion I prefer to use those varieties of shales which are found abundantly in coal
measures which contain more or less alumina combined with silica, and which
generally also contain varying quantities of bituminous matter, but have little
iron, lime, or other substance which might injure the quality of the alum or
interfere with its profitable production. These shales or matters are known
by various names, and they differ in appearance, those I have used are called
blaze," "cannell-slaté," "coal-metal," "fire-clay-stone," &c., and they break

page_text: up into shivers or lamina, on being for some time exposed to atmospheric
influence before or after being calcined. I calcine them in the following
manner: I form on the ground a number of air channels, one or two feet
apart. Each of these channels is constructed by laying two parallel lines of
common bricks, each line about four inches distant from the other, and I lay.
bricks across so as to form a channel of about four inches section, the bricks
being laid loosely so as to allow the air to pass freely. On these channels I
lay burning coal, and then some of the more bituminous shales broken into
small pieces, say to àbout the size of stone broken for mending roads, and
when the combustion is commenced I lay over less bituminous shales; these
are laid on gradually, taking care not to put out the fire thereby, and at the
same time keeping down the heat to a low red, as a higher heat is apt to flux
some of the materials, and thus render them less soluble in the acid. Shales
without bitumen, and prepared clays may be prepared in like manner for
the purpose of this part of my Invention, by mixing them with small coal
or sawdust. The heaps are allowed to burn out and cool down, which will
be in about eight to ten days. I take the materials (thus prepared, and
without reducing them to powder, which it is important to avoid, as it saves
expense, and the process would be less advantageously carried out if the same
were reduced to powder), and I put them into large square vessels of wood
lined with lead, nearly filling the vessels therewith, and I cover the materials
with diluted sulphuric acid, of 1.25 to 1.3 specific gravity, and I apply heat
to the materials in the vessels by means of steam pipes or other convenient
'njeans, so as to keep up the temperature to about two hundred degrees of
Fahrenheit, for from twenty to twenty-four hours, at which time the acid will
be nearly or quite neutralized, and the liquor is then to be run off into vessels
to be chrystallized as heretofore and as is well understood; and fresh diluted
acid is to be placed on the materials after having drawn off the liquor, and
the same is to be kept heated as before for about the same time, when the
liquor is to be run off and chrystallized as before mentioned, and again a
fresh quantity of diluted acid is to be applied; and these processes are to
be repeated till diluted acid has been applied six or seven times, and the
liquor produced as repeatedly drawn off, when the material will be so spent
as not to be worth further treatment with acid; and the time of digesting the
material with the acid will encrease after the first three processes, the last
requiring about forty-eight hours. In order to prevent waste of acid after
the last drawing off, I fill up the vessel containing the materials (which have
been so treated) with water, which being run off I use to dilute sulphuric
acid, and I also use the mother liquors obtained from the chrystallizing vessels

page_text: to dilute sulphuric acid, and also for dissolving the salts of potash or ammonia
used in chrystallizing alum.
Having thus described the nature of my Invention, and the best means of
performing the same, I would have it understood that I do not confine myself
to the precise details, so long as the peculiar character of either part of my
Invention be retained; but what I claim is,-
First, the mode of manufacturing copperas by applying a product (obtained
from pyrites by burning) and digesting the same with diluted sulphuric acid,
as above described. And,
Secondly, I claim the mode of manufacturing solutions of sulphate of
alumina, by causing shales or matters to be digested repeatedly with diluted
sulphuric acid, as herein described.
In witness whereof, I, the said Peter Spence, have hereunto set my hand
and seal, this Twenty-third day of May, in the year of our Lord One