IMPROVEMENTS IN THE MANUFACTURE OF SODA
Year: 1875

page_text: LETTERS PATENT to John Imray, of No. 20, Southampton Buildings,
Chancery Lane, in the County of Middlesex, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF SODA."-A communication from
abroad by Alexander Alexandrovitsch Scherbascheff, of Charkow,
in the Empire of Russia.
Sealed the 12th November 1875, and dated the 22nd June 1875.
PROVISIONAL SPECIFICATION left by the said John Imray at the
Office of the Commissioners of Patents, with his Petition, on the
22nd June 1875.
I, JOHN IMBAY, of No. 20, Southampton Buildings, Chancery Lane,
in the County of Middlesex, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN THE MANUFACTURE OF SODA," to be as
follows:-
This Invention relates to the manufacture of soda from common salt
and carbonate of ammonia. The usual process for this consists in sub-
jecting a solution of these substances to the action of carbonic anhydride
under a considerable pressure at a low temperature. It has been found

page_text: that when ordinary soda, that is, carbonate of soda combined with 10
equivalents of water is dissolved in water and heated to about 95° Fahr.,
it can retain in combination no more than 7 equivalents of the water,
whilst at still higher temperatures it loses still more of the combined
water, retaining only one equivalent thereof, the dissociation of the water
being more complete the higher the temperature of the solution, and
being rendered more energetic by the presence of ordinary salt. Hence,
when salt and carbonate of ammonia in solution are exposed in the same
vessel to an elevated temperature, a double reaction ensues, producing
chloride of ammonium and carbonate of soda combined with one
equivalent of water, the latter salt being almost insoluble. The
elevation of temperature is however limited by the circumstance that
the carbonate of ammonia becomes decomposed when the heat is too
great, so that a temperature of from 140° to 160° Fahr. should not be
exceeded, the process being so conducted that the almost insoluble soda
is precipitated to the bottom of the vessel while the solution of chloride
of ammonium can be removed and crystallised. For this purposo a deep
vessel is half filled with water or with brinc, and in the vessel one or
more baskets or other suitable porous receptacles containing salt in large
fragments are suspended. The liquid is then warmed to about 140°
Fahr. by means of a steam or hot air coil or otherwise, and when this
temperature is attained there are hung by the side of the salt baskets or
receptacles others of the same kind containing carbonate of ammonia,
whereupon a reaction ensues, soda being precipitated in the form of a
crystalline and almost insoluble powder, and sal ammoniac remaining in
solution. During this reaction some ammonia and carbonic anhydride
escape in the gaseous form; to avoid the loss of these materials during
the reaction the vessel is tightly closed, having only a communication
by a pipe to a second vessel, where these gases are absorbed in liquid.
For greater facility of closing the vessel it is made with a cover
presenting apertures for the insertion and removal of the baskets or
porous receptacles, which apertures can be readily closed by lids. The
operation is complete when the liquid in the vessel is a saturated
solution of sal ammoniac, which can be ascertained by testing in the
usual way. When the point of saturation is attained, the baskets or
porous receptacles containing the salt and the carbonate of ammonia are
removed, and suspended in the liquid of the second vessel, which had
received the carbonic anhydride and ammonia from the first. The
contents of the first vessel are then for some time maintained at a

page_text: temperature of 140° to 160° Fahr., till all the soda is precipitated,
whereupon the liquid is drawn off into crystallising vessels, and the soda
is removed and dried by a centrifugal machine, or otherwise. As some
sal ammoniac is mingled with it, washing may be first effected in the
centrifugal machine by a boiling solution of soda, and the product being
rapidly dried is comparatively pure soda ready for use.
The sal ammoniac is converted in the usual way into carbonate of
ammonia, which is used again for the production of soda, and the
residuary liquid is poured into the emptied vessel to absorb the gases
from the second vessel in which the reaction is carried on. When the
salt to be operated on is in fine particles, it may be put in the vessel
without a basket and continually stirred therein, agitation having great
utility in furthering the reaction.
It is to be understood that the quantities of salt and carbonate of
ammonia subjected to treatment depend upon the condition of the
residuary liquid, for example, when the sal ammoniac is crystallised at a
low temperature less of the salt will remain in the liquid, which will
consequently be capable of dissolving a larger quantity at the next
operation. It will thus be seen that by the process above described,
carbonate of soda is produced from the reaction of salt, and carbonate of
ammonia at a temperature of 140° to 160° Fahr., without the application
of carbonic anhydride at a high pressure.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said John Imray in the Great Seal Patent Office
on the 16th November 1875.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
IMRAY, of No. 20, Southampton Buildings, Ohancery Lane, in the
County of Middlesex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Twenty-second day of June, in the
year of our Lord One thousand eight hundred and seventy-five, in
the thirty-eighth year of Her reign, did for Herself, Her heirs and
successors, give and grant unto me, the said John Imray, Her special

page_text: license, that I, the said John Imray, my executors, administrators, and
assigns, or such others as I, the said John Imray, my executors, adminis-
trators, 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 MANU-
FACTURE OF SODA,” a communication to me from abroad by Alexander
Alexandrovitsch Scherbascheff, of Charkow, in the Empire of Russia,
upon the condition (amongst others) that I, the said John Imray,
my executors or administrators, by an instrument in writing under
my, or their, or one of their hands and seals, 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 John Imray, do hereby declare
the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by
the following statement thereof, that is to say :—
2
This Invention relates to the manufacture of soda from common salt
and carbonate of ammonia. The usual process for this consists in sub-
jecting a solution of these substances to the action of carbonic anhydride
under a considerable pressure at a low temperature. It has been found
that when ordinary soda, that is, carbonate of soda combined with 10 2
equivalents of water is dissolved in water and heated to about 95° Fahr.,
it can retain in combination no more than 7 equivalents of the water,
whilst at still higher temperatures it loses still more of the combined
water, retaining only one equivalent thereof, the dissociation of the
water being more complete the higher the temperature of the solution, 8
and being rendered more energetic by the presence of ordinary salt.
Hence, when salt and carbonate of ammonia in solution are exposed in
the same vessel to an elevated temperature, a double reaction ensues,
producing chloride of ammonium and carbonate of soda combined with
one equivalent of water, the latter salt being almost insoluble. The 3
elevation of temperature is however limited by the circumstance that
the carbonate of ammonia becomes decomposed when the heat is too

page_text: great, so that a temperature of from 140° to 160° Fahr. should not be
exceeded, the process being so conducted that the almost insoluble soda
is precipitated to the bottom of the vessel, while the solution of chloride
of ammonium can be removed and crystallised. For this purpose a deep
vessel is half filled with water or with brine, and in the vessel one or
more baskets or other suitable porous receptacles containing salt in large
fragments are suspended. The liquid is then warmed to about 140°
Fahr. by means of a steam or hot air coil, or otherwise, and when this
temperature is attained, there are hung by the side of the salt baskets or
receptacles others of the same kind containing carbonate of ammonia
whereupon a reaction ensues, soda being precipitated in the form of a
crystalline and almost insoluble powder, and sal ammoniac remaining in
solution. During this reaction some ammonia and carbonic anhydride
escape in the gaseous form; to avoid the loss of these materials during
the reaction the vessel is tightly closed, having only a communication
by a pipe to a second vessel, where these gases are absorbed in salt
solution or brine. For greater facility of closing the vessel it is made
with a cover presenting apertures for the insertion and removal of the
baskets or porous receptacles, which apertures can be readily closed by
lids. The operation is complete when the liquid in the vessel is a
saturated solution of sal ammoniac, which can be ascertained by testing
in the usual way. When the point of saturation is attained the baskets
or porous receptacles containing the salt and the carbonate of ammonia
are removed, and suspended in the liquid of the second vessel, which had
received the carbonic anhydride and ammonia from the first.
The
contents of the first vessel are then for some time maintained at a
temperature of 140° to 160° Fahr., till all the soda is precipitated,
whereupon the liquid is drawn off into crystallising vessels, and the soda
is removed by an opening in the bottom of the vessel, and dried by a
centrifugal machine, or otherwise. As some sal ammoniac is mingled
with it, washing may be first effected in the centrifugal machine by a
boiling solution of soda, and the product being rapidly dried is com-
paratively pure soda ready for use.
-
The sal ammoniac is converted in the usual way into carbonate of
ammonia which is used again for the production of soda, and the
residuary liquid is poured into the emptied vessel to absorb the gases.
from the second vessel in which the reaction is carried on. When the
salt to be operated on is in fine particles, it may be put in the vessel

page_text: without a basket and continually stirred therein, agitation having great
utility in furthering the reaction.
•
It is to be understood that the quantities of salt and carbonate of
ammonia subjected to treatment depend upon the condition of the
residuary liquid, for example, when the sal ammoniac is crystallised at a 5
low temperature, less of that salt will remain in the liquid, which will
consequently be capable of dissolving a larger quantity of carbonate at
the next operation.
Having thus described the nature of the said Invention, and in what
manner the same is to be performed, as communicated to me by my 1
foreign correspondent, I claim, the process' substantially as hercin
described for manufacturing soda by subjecting salt and carbonate of
ammonia in solution to a temperature of 140° to 160° Fahr.
In witness whereof, I, the said John Imray, have hereunto set
my hand and scal, this Sixteenth day of November, in the year 1
of our Lord One thousand eight hundred and seventy-five.
TATTN THDAY