IMPROVEMENTS IN THE MANU- FACTURE OF CARBONATE OF SODA
Year: 1859

page_text: LETTERS PATENT to William Gossage, of Widnes, in the County of
Lancaster, Chemist, for the Invention of "IMPROVEMENTS IN THE MANU-
FACTURE OF CARBONATE OF SODA."
Sealed the 15th May 1860, and dated the 18th November 1859.
PROVISIONAL SPECIFICATION left by the said William Gossage at
the Office of the Commissioners of Patents, with his Petition on the
18th November 1859.
I, WILLIAM GOSSAGE, of Widnes, in the County of Lancaster, Chemist, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE
MANUFACTURE OF CARBONATE OF SODA," to be as follows:-
My improvements apply to the manufacture of carbonate of soda when this
is produced by the decomposition of sulphate of soda so as to produce sulphide
of sodium, and by the subsequent conversion of such sulphide of sodium into
carbonate of soda by means of carbonic acid.
In the methods heretofore employed for producing sulphide of sodium by
the decomposition of sulphate of soda (preparatory to the manufacture of
carbonate of soda) the sulphate of soda has been mixed with small coal or
coke, and the mixture caused to be fluxed by the application of heat.
My improvements comprize the decomposition of sulphate of soda into sulphide
of sodium (preparatory to the manufacture of carbonate of soda) by the action
of carbon, at such temperatures as are insufficient to cause the mixture to
become fluxed, and I prefer to effect such decomposition in vessels or furnaces,
to which heat is applied by transmission, in place of this being applied by the
direct action of flame.

page_text: My improvements also comprize the use of carbonic acid gas produced by
the decomposition of sulphate of soda into sulphide of sodium, without fluxing
for the decomposition of sulphide of sodium so obtained, and consequent
production of carbonate of soda.
By means of my improvements I am enabled to effect the decomposition of
sulphate of soda (for the manufacture of carbonate of soda) without causing so
great a destruction of the furnaces employed as when sulphate of soda is
decomposed by fluxing. I am also enabled to apply the carbonic acid gas
which is evolved during such decomposition in the manufacture of carbonate
of soda, and to prevent the waste of soda by sublimation, which takes place
when sulphate of soda is decomposed by fluxing.
My improvements also comprize the use of oxide of iron in conjunction with
carbonic acid for effecting the decomposition of sulphide of sodium and pro-
duction of carbonate of soda, and the use of the compound of sulphur and iron
produced by such use of oxide of iron and carbonic acid in the production of
a further quantity of sulphate of soda.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Gossage in the Great Seal Patent Office on the
18th May 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
GOSSAGE, of Widnes, in the County of Lancaster, Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Eighteenth day of November, in the year of our
Lord One thousand eight hundred and fifty-nine, in the twenty-third year
of Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said William Gossage, Her special license that I, the said
William Gossage, my executors, administrators, and assigns, or such
others, as I, the said William Gossage, 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 CARBONATE OF SODA,"
upon the condition (amongst others) that I, the said William Gossage, 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

page_text: 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 William Gossage, 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) :-
My improvements apply, firstly, to the manufacture of carbonate of soda
when this product is obtained by decomposing sulphate of soda into sulphide of
sodium, and subsequently converting such sulphide of sodium into carbonate
of soda by the action of carbonic acid; also to the use of carbonic acid evolved.
by such decomposition of sulphate of soda.
Secondly, to the use of oxide of iron in conjunction with carbonic acid for-
effecting the decomposition of sulphide of sodium, and consequent production
of carbonate of soda.
And thirdly, to the use of the compound of sulphur and iron (produced by-
such use of oxide of iron and carbonic acid) for the production of a further
quantity of sulphate of soda suitable to be used in the manufacture of carbonate
of soda.
In the methods heretofore employed for producing sulphide of sodium by
the decomposition of sulphate of soda (preparatory to the manufacture of
carbonate of soda), the sulphate of soda has been mixed with small coal or
coke, and the mixture caused to be fluxed in furnaces by the application:
of heat.
By means of the first part of my improvements I effect the decomposition of
sulphate of soda into sulphide of sodium (preparatory to the manufacture of
carbonate of soda) by the action of carbon at such temperatures as are in-
sufficient to cause the mixture to become fluxed; and I employ carbonic acid"
produced by such decomposition for effecting the conversion of sulphide of
sodium into carbonate of soda, and consequent liberation therefrom of sulphur.
I effect such decomposition of sulphate of soda and production of sulphide of
sodium by introducing a mixture of sulphate of soda in powder, with about
half its weight of small coal or one-third its weight of ground coke into such a
furnace as is known to soda manufacturers as a blind furnace, that is,. a closed"
furnace, in which the heat applied is transmitted through the brickwork com-
posing the floor and interior roof of such furnace (furnaces of this kind are
commonly used by soda manufacturers in the second stage of the manufacture
of sulphate of soda). I cause such a degree of heat to be applied to the said
mixture as will be just insufficient to cause the sulphate of soda to become

page_text: fluxed, and I assist the decomposition by raking, and thus mixing the contents
of the furnace occasionally. I continue the application of heat to the said
mixture until I find that samples taken therefrom indicate by testing that all
or nearly all the sulphate of soda has become decomposed. I then withdraw
the charge as quickly as may be practicable into iron vessels, which I cover so
as to exclude atmospherical air, and thus prevent oxydation of the sulphide of
sodium. The decomposition of sulphate of soda by means of carbon as herein-
before described, produces a large quantity of carbonic acid gas; I withdraw
such carbonic acid gas from the furnace in which it is produced by means of an
air pump or centrifugal fan, or by other suitable means; and I transfer such
gas into apparatus wherein it may be applied to the decomposition of sulphide
of sodium, and consequent production of carbonate of soda and liberation of
sulphur; or such gas may be employed for the production of bi-carbonate of
soda or sesqui-carbonate of soda. During the periods at which the said
mixture of sulphate of soda and coal or coke is being introduced into or with-
drawn from the furnace, or the charge is undergoing the operation of raking
or mixing, I disconnect the furnace from the apparatus used for withdrawing
carbonic acid gas, and after such periods I close up and lute the doors of the
furnace, so as to exclude atmospherical air, and I then re-establish the con-
nection of the furnace with the gas-withdrawing apparatus.
I effect the decomposition of sulphide of sodium (obtained as herein-before
described) and production of carbonate of soda therefrom, either by exposing
such sulphide of sodium in a state of moistened powder mixed with small
pieces of coke placed upon perforated trays (contained in such an apparatus as
is commonly employed in the purification of coal gas) to the action of carbonic
acid gas, or by causing a solution of such sulphide of sodium in water to be
acted upon by carbonic acid gas, or by mixing such sulphide of sodium with
bi-carbonate or sesqui-carbonate of soda, thereby producing carbonate of soda
and liberating sulphuretted hydrogen gas.
In effecting the second part of my improvements I mix oxide of iron in
powder with sulphide of sodium, and I cause such mixture either in the state
of moistened powder or mingled with such a proportion of water as to render
it fluid, to be acted upon by carbonic acid gas, or by the carbonic acid of
bi-carbonate or sesqui-carbonate of soda. When the mixture of sulphide of
sodium and oxide of iron is used in the state of moistened powder, I prefer to
use such an apparatus as is commonly employed for the purification of coal
gas, and I place the said mixture on the perforated shelves or trays of such
apparatus, and cause carbonic acid gas to percolate through such mixture. I
continue the application of carbonic acid gas to such mixture until I find by

page_text: testing samples that the whole or nearly the whole of the sulphur previously
contained in the sulphide of sodium has become transferred to the iron; I
then lixiviate the mixture with water, and obtain carbonate of soda in solution
and insoluble sulphide of iron.
When the sulphide of sodium and oxide of iron are subjected to the action
of carbonic acid gas in the state of fluid mixturé, I use such a proportion of
water as I find to be sufficient to give the requisite degree of fluidity, and
I inject carbonic acid gas into such fluid mixture by means of a force pump,
and I cause the mixture to be well agitated, so as to keep the oxide of iron in
suspension. I continue the injection of carbonic acid gas into the mixture
until. I find by testing that the whole, or nearly the whole, of the sulphur
previously contained in the sulphide has become transferred to the iron;
I then allow the mixture to remain quiet, and draw off the solution of
carbonate of soda from the insoluble sulphide of iron produced, and I wash the
latter with water to extract soluble matter therefrom. When I cause sulphide
of sodium to be decomposed by bi-carbonate or sesqui-carbonate of soda in the
presence of oxide of iron, I prepare a solution of sulphide of sodium, and I add
thereto oxide of iron in powder, also such a proportion of bicarbonate or sesqui-
carbonate of soda as contains about one-tenth part more carbonic acid (above
the proportion requisite for the constitution of mono-carbonate of soda) than is
sufficient to convert the sulphide of sodium into carbonate of soda. I cause
the mixture to be heated and well agitated, and I continue the agitation until
I find that the whole or nearly the whole of the sulphide of sodium has become
converted into carbonate of soda; I then separate the carbonate of soda and
sulphide of iron produced.
In using oxide of iron for assisting the decomposition of sulphide of sodium,
I employ such a proportion of oxide as contains about one-tenth part more
iron than is sufficient to form mono-sulphide of iron with the sulphur present
in the sulphide of sodium employed. I find that oxide of iron obtained by
burning off sulphur from iron pyrites in the ordinary manufacture of sulphuric
acid is suitable when reduced to powder for effecting this second part of my
improvements; also more particularly the oxide of iron which is produced
from the sulphide of iron obtained by the decomposition of sulphide of sodium
by means of carbonic acid and oxide of iron. I obtain carbonic acid gas for
the purposes of my improvements by the means I have herein-before indicated
or by other well known means. Having obtained sulphide of iron by means
of my improvements, as hereinbefore explained, I apply such sulphide of iron
to the production of sulphate of soda. In effecting this, the third part of my
improvements, I either cause such sulphide of iron to be dried and then

page_text: exposed to heat and atmospherical air, so as to expel sulphur therefrom in the
state of sulphurous acid gas, which gas I conduct into vitriol chambers, so as
to produce sulphuric acid therefrom, and I obtain oxide of iron as a residuum,
or I mix such sulphide of iron with such a proportion of common salt as will
contain soda equivalent to the sulphur present in the sulphide of iron, and
I expose such mixture to a low red beat with access of atmospherical air, and
I thereby obtain sulphate of soda and oxide of iron, which I separate by
lixiviation. The operations of burning off sulphur as sulphurous acid gas from
sulphide of iron, and of obtaining sulphate of soda by the use of sulphide of
iron and common salt are well known to soda manufacturers.
I have herein-before described and ascertained the nature of my Invention,
and the means which I consider to be most suitable for effecting the same,
but I do not confine myself to the precise means herein described, as these
may be modified to some extent without departing from the nature of my
Invention.
I claim as the Invention secured to me by the Letters Patent herein-before
in part recited,
Firstly, the manufacture of carbonate of soda by causing sulphate of soda to
become decomposed into sulphide of sodium by the action of carbon at such
temperature as is insufficient to flux the mixture of sulphate of soda and
carbon employed, and converting the sulphide of sodium so obtained into
carbonate of soda by the action of carbonic acid; also the use of carbonic acid
obtained by such decomposition of sulphate of soda for the production of
carbonate of soda.
Secondly, the manufacture of carbonate of soda by the conjoined action of
oxide of iron and carbonic acid on sulphide of sodium, however such sulphide
of sodium may have been obtained.
Thirdly, the use of sulphide of iron obtained by the conjoined action of
oxide of iron and carbonic acid on sulphide of sodium, for the production of
sulphate of soda to be used for the manufacture of carbonate of soda.
In witness whereof, I, the said William Gossage, have hereunto set my
hand and seal, this Seventeenth day of May, in the year of our
Lord One thousand eight hundred and sixty.
WILL. (L.S.) GUSSAGE.