IMPROVEMENTS IN MANUFACTURING THE PRUSSIATES OF POTASH AND SODA
Year: 1854

page_text: LETTERS PATENT to Peter Spence, of Pendleton, near Manchester, in
the County of Lancaster, Manufacturing Chemist, for the Invention of
PROVISIONAL SPECIFICATION left by the said Peter Spence at the
Office of the Commissioners of Patents, with his Petition, on the
21st January 1854.
.
I, PETER SPENCE, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN MANUFACTURING THE PRUSSIATES OF POTASH AND SODA ""
as follows:
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The object of this Invention is to effect the manufacture of prussiates of
potash and soda in a more economic manner than heretofore.. To this end I>
use the sulphate of potash and the sulphate of soda instead of the potash and
pearlash and the carbonate of soda now generally employed. And in place of
obtaining cyanogen (for the production of these prussiates) from the animal:
matter now used, I employ old leather, such as old shoes; or other refuse old
leather, and operate upon it in the manner at present adopted when other;
animal matters are employed for the like purpose.
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page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Peter Spence in the Great Seal Patent Office on the 19th
July 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, PETER
SPENCE, of Pendleton, near Manchester, in the County of Lancaster, Manu-
facturing Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-first day of January, in the year of our Lord
One thousand eight hundred and fifty-four, in the seventeenth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said Peter Spence, Her especial licence that I, the said Peter Spence, my
executors, administrators, and assigns, or such others as I, the said Peter
Spence, 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, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the Channel
Islands, and Isle of Man, an Invention for "IMPROVEMENTS IN MANUFACTURING
THE PRUSSIATES OF POTASH AND SODA," upon the condition (amongst others) that
I, the said Peter Spence, 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 Peter Spence, do hereby declare the
nature of my 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):
The object of this Invention is to effect the manufacture of prussiates of
potash and soda in a more economic manner than heretofore. To this end I
use the sulphate of potash and the sulphate of soda instead of the potash and
pearlash and the carbonate of soda now generally employed. And in place of
obtaining cyanogen (for the production of these prussiates) from the animal
matter now used, I employ old leather, such as old shoes or other refuse old
leather, and operate upon it in the manner at present adopted when other
animal matters are employed for the like purpose.
In describing more particularly my said Invention, I shall allude only to

page_text: the method of manufacturing prussiate of potash; but the same directions are
applicable to the manufacture of prussiate of soda, only using sulphate of soda
in place of sulphate of potash. And I use for the manufacture of prussiate of
potash, by my said Invention, the same sort of pots or culcining vessels as are
now in ordinary use and well known when prussiate of potash is manufactured
from pearlash or potash and ordinary animal matter, and I raise the heat of
the pots I so use by similar means, and to the same degree of heat as is now
in use in the said manufacture and as is well known. In my new process for
the manufacture of prussiate of potash I use sulphate of potash of considerable
purity, and I prefer that it should be nearly free from other salts, and I charge
it into the pots in as large a quantity as they will conveniently work, but allow
room for the expansion or swelling that takes place when the old leather is
introduced. When the sulphate of potash is brought to a full red heat it is
fluxed or becomes pasty or semi-fluid. I now take old leather, such as old
shoes or other refuse leather, and which I procure from parties who collect
such refuse matters, and add it gradually and in a dry state to the fused
sulphate of potash in the pots, diligently stirring after each addition of the old
leather, and adding further quantities as soon as that put in has become
charred and mixed with the sulphate of potash. When I have added as much
dry leather as double the weight of sulphate of potash used, I find the mix-
ture to grow thick, and I then add no more leather. I now keep up the heat
for three or four hours, and keep the pots during that time completely closed,
except only a small vent to allow the gasses to escape, but not to allow air
to enter, and I open the pots and stir the mixture once an hour during that
time. I now judge the calcination to be completed, and I open the pots and
lade out the calcined material, and then introduce a new charge to be operated
upon as I have now described. I now take the calcined material from the
pots, or the metal as it is sometimes called, and put it into a vessel with water,
and applying heat, thereby dissolve out all the soluble matter it contains, and
after allowing the sediment to subside I run off the liquor and evaporate it till
of sufficient strength, as is well known, and set it aside to crystallise, by which
I obtain a crop of impure prussiate of potash crystals, and which are after-
wards purified by recrystalization, as is well known and practised; the mother
liquor, however, still contains a large quantity of prussiate of potash in solution,
and which cannot be crystalised out of it; and it also contains carbonate of
potash and sulphate of potassium. In the ordinary mode of manufacturing prus-
siate of potash, the crude mother liquors are boiled down to dryness, and the
salt thus obtained is returned to the calcining pots along with a new quantity of

page_text: pearlash or potash. Instead of. so boiling down I add to the crude mother
liquors sufficient sulphuric acid to convert all the before-named compounds of
potash into sulphate of potash; and I know when sufficient acid has been
added, by the liquor ceasing to, effervesce, and I then add to it a solution of
copperas or sulphate of iron as long as any precipitate is thrown down... I
allow this precipitate, which is prussian blue, to fall to the bottom, and the
clear solution of sulphate of potash is now run off' from it; water is then added
to wash the prussian blue, and after stirring, and again settling, the clear
liquor is run off a second time and added to the liquor which was previously
run off the prussian blue; these liquors are now boiled down to dryness, and
the sulphate of potash thus obtained is returned to the calcining pots along
with new quantities of sulphate of potash for again charging the said caleining
pots. The prussian blue being now in the state of a very liquid pulp, I take
and add to it the next charge of calcined material or metal from the pots, and
put both together into the vessel, in which I dissolve out the solution from the
said metal, and after adding a sufficient quantity of water, I boil altogether by
a steam pipe opened into the vessel, as is well known, and I let them; so boil
for at least an hour, which serves to dissolve out the soluble matter from the
calcined material or metal, and also enables the carbonate of potash and
sulphide of potassium to re-act upon the prussian blue and take from it all or
nearly all the prussic acid which it contained; and the liquor being now
settled and evaporated till of sufficient strength, will yield a much larger crop
of impure prussiate of potash crystals than it would without, the use of the
prussian blue, as now described; the mother liquor I treat as before. with
sulphuric acid, and again obtain prussian blue, to be used with the next charge
of calcined material, in the manner now described. I know that Mr. Swin-
dles obtained Letters Patent for producing prussiate of potash as a secondary
result from calcining sulphate of potash in furnaces with small coal, chiefly for
the manufacture of pearlash or carbonate of potash from said sulphate-of
potash. I am not aware that sulphate of potash has ever been used along
with animal matters, or substances containing animal matters, for the manu-
facture of prussiate of potash. In various chemical works, treating of said
manufacture I have read directions given for purifying the pearlash and
potash used in said manufacture from all contamination of sulphate of potash,
as being pernicious to said manufacture. I am also aware that leather has
sometimes been used along with pearlash and potash for said manufacture,
and I do not claim its use when so used as part of my Invention; but what I
clo claim is,-

page_text: First, the sole use of sulphate of potash for the manufacture of prussiate of
potash, and of sulphate of soda for the manufacture of prussiate of soda, in all
cases when animal matters or substances containing animal matters are used
or calcined along with said sulphates of potash and soda for said mana-
factures.
Second, the sole use of old and refuse leather for the manufacture of prus-
siates of potash and soda, in all cases where such old or refuse leather is used
or calcined along with sulphates of potash or soda for said manufactures.
Thirdly, the sole use of the mode described, by which all the alkali in the
crude prussiate mother liquors is converted into sulphate by the use of
sulphuric acid, and, the prussian blue then obtained from such liquors by the
use of sulphate of iron is added to the calcined material from the pots, and by
which a larger produce of prussiate is obtained, while the solution of sulphate
of potash or soda is boiled down to dryness and again calcined for said
manufacture, as herein-before described.
In witness whereof, I, the said Peter Spence, have hereunto set my
hand and seal, this Fifteenth day of July, in the year of our Lord One
thousand eight hundred and fifty-four.