IMPROVEMENTS IN THE MANUFACTURE OF THE CARBONATES AND PRUSSIATES OF POTASH AND SODA
Year: 1854

page_text: LETTERS PATENT to Thomas Bramwell, of Enfield House, near Gateshead
on Tync, in the County of Durham, for the Invention of "IMPROVEMENTS
IN THE MANUFACTURE OF THE CARBONATES AND PRUSSIATES OF POTASH AND
SODA."
Sealed the 17th August 1854, and dated the 9th June 1854.
PROVISIONAL SPECIFICATION left by the said Thomas Bramwell at the
Office of the Commissioners of Patents, with his Petition, on the 9th
June 1854.
I, THOMAS BRAMWELL, of Enfield House, near Gateshead on Tyne, in the
County of Durham, do hereby declare the nature of the Invention for "Iж-
PROVEMENTS IN THE MANUFACTURE OF THE CARBONATES AND PRUSSIATES OF POTASH
AND SODA" to be as follows:-
Heretofore prussiates of potash and soda has been manufactured by heating
carbonates of potash and soda with animal matters.
Now, my Invention consists in using the sulphates of potash and soda, or
the sulphide of potassium and sodium, as substitutes for the carbonates above
mentioned, and I mix with such sulphates or sulphides an equivalent proportion
of iron, either in the metallic or other form, with which the sulphur combines
during the process.
I also separate carbonate of potash from carbonate of soda, by evaporating

page_text: the solution until the carbonate of soda is deposited, and the purified carbonato
of potash thus obtained may be used for manufacturing prussiate of potash.in
tho ordinary manner, or for other purposes. I also purify, if required, the
solutions of the said potash and soda salts of sulphides and silicates, by means
of caustic lime and oxide of iron boiled in their solutions.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Bramwell in the Great Seal Patent Office on the
4th December 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
BRAMWELL, of Enfield House, near Gateshead on Tyne, in the County of
Durham, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing dato 'the Ninth day of June, 'in the year of our Lord Ono
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
Thomas Bramwell, Her special licence that I, the said Thomas Bramwell, my
exccutors, administrators, and assigns, or such others as I, the said Thomas
Bramwell, 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 THE MANUFACTURE
OF THE CAREONATES AND PRUSSIATES OF POTASH AND SODA," upon the condition
(amongst others) that I, the said Thomas Bramwell, 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 Thomas Bramwell, do hereby declaro.
the nature of the said Invention, and in what manner the same is 'to bo
performed, to be particularly described and ascertained in and by the following
statement thereof (that is to say):-
The present mode of making prussiato of potash or soda is by fluxing pot
or pearlash or soda of commerce with animal matters, in cast-iron pots or

page_text: cylinders, at a high heat; the fluxed mass drawn out is, when cold, "lixiviated
in water, the prussiate of potash or soda crystallized out, and the remaining
alkaline solution evaporated down to dryness, and is thus returned back (under
the name of return alkali), to undergo the same operation again, with a portion
of fresh pearlash or soda added, to supply the loss or waste of the previous
charge; thus 50 lbs. old or return potash and 20 lbs. of new is an ordinary
charge. Now, instead of using pot or pearlash (carbonate of potash), or soda
alkali, to supply this waste or loss, I use sulphate of potash or soda, which is a
much cheaper salt; or I use sulphide (sulphuret) of potassium or sodium, made
simply by fluxing the sulphates with coal or other carbonaceous matter; and
along with the said sulphates or sulphides I put a portion of iron, (which is
best in the shape of borings, turnings, or clippings,) in quantity equivalent to
the sulphur contained in the said sulphur salts, namely, 5 to 6 lbs. of iron to
20 lbs. of sulphur salts; or, instead of metallic iron, an oxide or ground iron ore
may be used. The sulphur in the said alkaline salts unites with the iron
during the operation (which is conducted in the ordinary manner), forming
insoluble sulphide or sulphuret of iron, which remains in the black residuum on
lixiviation of the mass in water, leaving in solution the prussiate of potash or
soda to be crystallized out in the ordinary way. When prussiate of potash is
made from the sulphate of potash salts from kelp, which always contain a
portion of soda salts, I find it necessary from time to time to separate the
soda salts from the potash solution; to effect which, I boil the return potass
solution after the prussiate of potash is crystallized out, until the carbonate
of soda begins to fall, or salt down, as it is termed, and if the solution con-
tains about 30 per cent. of carbonate of soda, which is about a proportion,
before it is needed to separato it, it will commence to do this when the solu-
tion is at 70 to 75 of Twaddell's hydrometer, or specific gravity 1.350 to 1.375,
and which must be taken out of the boiler as it falls down in the usual way of
salting down; so long as the soda salt continues to fall, the specific gravity of
the liquid does not increase, notwithstanding the boiling of the liquor is con-
tinued; and whenever an increase of the specific gravity of the liquid commences
to take place, it shews the carbonate of soda is all salted out. The remaining
solution of carbonate of potash is then run off into a cooler to crystallize, and
separate out the muriates and other neutral salts during cooling; after which
it is to be boiled to dryness and used in the fluxing process in the usual way as
return potash. The carbonate of soda thus settled out I dissolve in water, and
boil the clear solution to crystallize into soda of commerce; or it may be made
into soda ash in the usual way. By the continued operation of returning back

page_text: the carbonate of potash or soda to be worked over and over again, it becomes
much contaminated with sulphur, forming sulphides of these alkalies and also
in the present mode of making soda and potash alkalies (carbonate of potash or
soda), by fluxing the sulphates of these alkalies with carbonate of lime and
coal or coke, a considerable quantity of sulphide exists in the solution lixiviated
from the mass, which, in the usual operation of carbonating the alkali in a
reverberatory furnace, becomes converted back again into sulphate, by which
there is a considerable loss of alkali. Now, my improvement consists in both
these cases in freeing these alkalies from the sulphide, by means of finely
divided iron or black oxide of iron in powder, which is either added to their
solutions, or the said solutions are filtered through a bed of the oxide of iron
powder; in either case most of the sulphur unites to the iron, forming
sulphide of iron. The black oxide or fine iron powder may be conveniently
made, by heating at a red heat, ground red, hoematite iron ore, with an
equivalent proportion of coal or carbonaceous matter, keeping it from tho
action of the atmospheric air when taken from the furnace until cold, or it
will form again the red oxide.
When the black powdered iron ore in the abovo process becomes saturated
with sulphur, the alkali being washed out of it, it may again be made fit for
use, by heating it at a low red heat for two or three days in a furnace or a flue
heated by the waste heat from another operation, as a heat below that of
redness is sufficient for the purpose. As soon as the sulphur is driven off it
must be furnaced with coal, as above described, to make it into black oxide,
and it may be thus used continuously over again. To know if the sulphur is
entirely driven off the oxide after heating, a little weak sulphuric acid added to
it should give no smell of sulphur. After the alkaline solution has passed
through or been mixed with the oxide of iron, it is necessary to add a littlo
caustic lime, say, five per cent. in weight of dry lime, in the state of cream,
which will free it from any iron may exist in the solution, and the action is
more perfect if the solution is boiled or heated.
Having thus described my several improved processes, I claim as new,-
First, the use of sulphate of potash or sulphide of potassium, instead of pot
or pearlash of commerce, in the manufacture of prussiate of potash; or of
sulphate of soda or sulphide of sodium, instead of soda or carbonate of soda, in
the making of prussiate of soda, as above described.
Second, I claim the separation of carbonate of soda from a mixed solution of
carbonate of potash and soda, by means of salting out the carbonate of soda
by boiling, as described.

page_text: Third, I claim the separation of sulphur from solutions of potash or soda
salts containing sulphides, by means of black oxide or of finely divided iron, as
described, whether the said potash or soda salts be used in the making of
prussiates, or for the manufacture of carbonates, or other form of potash or soda
alkalies.
In witness whereof, I, the said Thomas Bramwell, have hereunto set my
hand and seal, this Second day of December, in the year of our
Lord One thousand eight hundred and fifty-four.
Witness,
WM CARGEY,
Heworth.
THOMAS BRAMWELL. (L.B.)