IMPROVEMENTS IN THE PROCESS OF MANUFACTURING SALTPETRE
Year: 1856

page_text: LETTERS PATENT to George Lürig, of the Town of Adelebsen, Hanover,
residing in Paris, Soap Manufacturer, for the Invention of "IMPROVEMENTS
IN THE PROCESS OF MANUFACTURING SALTPETRE."
PROVISIONAL SPECIFICATION left by the said George Lürig at the
Office of the Commissioners of Patents, with his. Petition, on the 18th
April 1856.
I, GEORGE LÜRIG, of the Town of Adelebsen, Hanover, residing in Paris,
Soap Manufacturer, do hereby declare the nature of the said Invention
for IMPROVEMENTS IN THE PROCESS OF MANUFACTURING SALTPETRE, to be as
follows:-
My Invention consists in using potash of commerce, nitrate of soda, sulphate
of potash, and quick lime, mixed together in certain proportions,.and in the
following manner, for manufacturing saltpetre:-
The potash and nitrate of soda are dissolved in water with the help of heat,
the solution is then boiled down till it marks 20 degrees of Beaumé's aerometer,
when the fire is stopped; then this said solution is poured upon the lime, pre-
viously placed in a suitable tub. The lime dissolves, and the mixture is stirred
up for a few minutes, and left to settle for a few hours; the liquor is then drawn
off and placed in a copper, fresh water is poured into the tub, it is again stirred
up, left to settle, and drawn off into the copper, where it is boiled till it marks
25 degrees on the aerometer. The lye, thus prepared and concentrated to 25°,

page_text: may be used for manufacturing soaps, and it is only after the separation of the
alkalies that it is used for manufacturing saltpetre. For making saltpetre, the
lye is drawn off into a copper and concentrated till it marks 33 degrees, it is
then left to cool and drawn off into a tub, where it is left at rest for 24 hours,
the liquor is then drawn off, and saltpetre crystals remain deposited on the
sides and bottom of the tub. This lye, just drawn off, is concentrated as before,
and gives some more crystals of saltpetre. By this process several drawings
off will have to be made, until the solution at 42° gives no more saltpetre.
The remaining liquor is potash lye, which may be used for making soap or
potash.
SPECIFICATION in pursuance of the, conditions of the Letters Patent, filed
by the said George Lürig in the Great Seal Patent Office on the 15th
October 1856.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, GEORGE
LÜRIG, of Adelebsen, Hanover, residing in Paris, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of April, One thousand eight hundred
and fifty-six, in the nineteenth year of Her reign, did, for Herself, Her heirs
and successors, give and grant unto me, the said George Lürig, Her special
license that I, the said George Lürig, my executors, administrators, and
assigns, or such others as I, the said George Lürig, my executors, admi-
nistrators, 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 THE PROCESS OF MANUFACTURING SALT-
PETRE, upon the condition (amongst others) that I, the said George Lürig,
my executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should particularly describe and ascer-
tain 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 George Lürig, 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):-

page_text: The Invention consists in manufacturing saltpetre by treating, in the manner
subsequently described, first, the common potash of commerce (carbonate of
potash); secondly, sulphate of potash; thirdly, nitrate of soda; fourthly, quick
lime.
First process. The proportions of the above materials which I use in this
process are as follows:-Sixty pounds carbonate of potash, forty pounds sulphate
of potash, one hundred and forty pounds nitrate of soda, one hundred and
eighty pounds quick lime. These quantities of carbonate and of sulphate of
potash and of nitrate of soda are placed together in a large boiling pan or
kettle, with enough water to dissolve them, heat being applied. When the
liquor after boiling for some time comes to mark twenty degrees on Beaumé's
saltareometer the fire is stopped, and the one hundred and eighty pounds of
quick lime above mentioned, being placed in a tub large enough for that
purpose, the solution is poured from the boiling pan on the quick lime, which
is dissolved by it. As soon as this result has been attained the mixture is
stirred for a few minutes, in order to get the compounds perfectly mixed
together. After allowing it to settle for three or four hours, the lime gathers
to the bottom, the superincumbent liquor is drawn off into a boiling pan of
suitable dimensions prepared for that purpose; but as all the alkaline salts
cannot be taken up from the lime by a first drawing, a fresh quantity of water
is poured into the boiling pan or kettle, and the same operation is repeated as
at first, that is to say, the liquor is stirred up again and left to settle, it is then
drawn off as before, and this second liquor is mixed in the boiling pan with the
first. The fire is then kindled under the boiling pan or kettle containing the
above drawn off liquors, which are boiled down till they mark twenty-five
degrees of Beaumé's areometer. When the solution or lie thus prepared has
attained this degree of concentration, it may be used for manufacturing hard
soap of any kind, and it is only after the alkalies have been separated that the
saltpetre is manufactured. Thus, for manufacturing the soap, the sediment in
the boiling pan is taken out, whilst for manufacturing saltpetre, the liquor is
drawn off and carried in another boiling pan, where it is boiled down till it
marks thirty-three degrees on Beaumé's areometer; the liquor is then left to
stand until it is lukewarm, and it is run out into a tub prepared for its reception,
where it is left at rest for twenty-four hours. At the end of that time the
mother liquor is drawn off from the crystals produced, by means of a cock or
otherwise, and all the crystals deposited over the sides and bottom are saltpetre ;
the mother liquor, however, contains some saltpetre still, but as it is not strong
enough to yield it by crystallisation, it should be concentrated anew; it is
accordingly poured out again into the kettle or pan and boiled down till it marks

page_text: thirty-three degrees, when the same process as before described is repeated.
All the liquors which have been submitted to the above process may yield a
residue of saltpetre.
Second process. Saltpetre may also be manufactured with the same materials
as before stated, mixed together in the following proportions:-Seventy pounds
carbonate of potash, forty pounds sulphate of potash, one hundred and ten
pounds nitrate of soda, and one hundred and eighty pounds quick limo.
Saltpetre is obtained by this process, following the same method as in the first
instance; the liquor should, however, be boiled down a longer time in order
to concentrate it to forty-two instead of thirty-three degrees of Beaumé's
areometer, as in the first process.
In order to obtain crystallized saltpetre by this method as many drawings
off as possible should be effected, that is to say, until the liquor concentrated
to forty-two degrees fails in giving crystals by cooling; the remaining liquor is
only a solution of potash, with which all kinds of soaps can be manufactured,
or from which refined potash (pearlash) can be obtained. All the alkalies
alkaline sulphates, and nitrates may be used in a similar manner for obtaining
the same result, namely, saltpetre, by the methods herein-before described.
It is clear that the proportion of the above-mentioned materials which enter
in the composition of the liquors, Ices, solutions, or mixtures used for manu-
.facturing saltpetre through the herein-before described processes, may be
modified; but my Invention consists, as before stated, in manufacturing saltpetre
by using common potash of commerce (carbonate of potash), alkaline sulphates,
nitrate of soda, and quick lime, in variable proportions, and in the manner
herein-before described.
In witness whereof, I, the said George Lürig, have hereunto set my hand
and seal, the Thirteenth day of October, in the year of our Lord One
thousand eight hundred and fifty-six.
Signed and sealed, in.
the presence of
Hinzilincing
G. LÜRIG. (L.S.)