IMPROVEMENTS IN THE MANUFACTURE OF POTASH AND SODA, AND THEIR CARBONATES
Year: 1840

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HUNT, of the Portugal Hotel, Fleet Street, in the City of London, Manufac-
turing Chemist, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria did grant
unto me Her Letters Patent, bearing date at Westminster, the Twenty-
first day of January, in the third year of Her reign, for making, using,
exercising, and vending, within England, Wales, and the Town of Berwick-
upon-Tweed, my Invention of "IMPROVEMENTS IN THE MANUFACTURE OF POTASH
AND SODA, AND THEIR CARBONATES," subject to the usual proviso obliging me
to describe and ascertain the nature of my said Invention, and in what manner
the same is to be performed.
NOW KNOW YE, that in compliance with the said proviso, I, the said
William Hunt, do hereby describe and ascertain the nature of my said
Invention, and in what manner the same is to be performed, in manner
following (that is to say) :-
I will first describe my Invention as I apply it to the manufacture of soda
and its carbonate, and afterwards as I apply it to the manufacture of potash
and its carbonate. In manufacturing carbonate of soda it is the usual practice
to decompose common salt by means of sulphuric acid, which has hitherto
been obtained for such purpose at great expence, and then to convert the
sulphate of soda produced by such decomposition into carbonate of soda. In
carrying my Invention into effect I decompose common salt either by means
of the metallic sulphates herein-after mentioned, or by means of sulphuric

page_text: acid obtained by the use of these sulphates and the metallic sulphurets herein-
after mentioned, or some of them, and I decompose the sulphate of soda
produced with coke or other carbonaceous matter, and by dissolving the
product of this decomposition I obtain a solution containing hydro sulphuret
of soda. I then decompose this hydro sulphuret by means of one of the
metallic oxides herein-after mentioned, and sulphur is thus transferred from
the solution of hydro sulphuret to the metal of the oxide employed. I thus
obtain a mixture of caustic soda in solution, and insoluble metallic sulphuret,
and I separate these and either subject the sulphuret to the processes herein-
after described, by which I obtain sulphuric acid and metallic oxide, or I
convert it into sulphate, and use this sulphate to decompose common, salt,
and produce sulphate of soda and muriate of the metallic oxide employed,
and afterwards obtain from this muriate metallic oxide. The oxide produced
by either of the means herein-before mentioned is suitable to be used for
decomposing hydro sulphuret of soda, and thereby producing a further quantity
of caustic soda in solution, and by using it for this purpose I reproduce a
metallic sulphuret suitable to be employed for producing a further quantity of
sulphuric acid, metallic sulphate, and metallic oxide. Having obtained caustic
soda in solution, I either use it in this state or I evaporate the solution to
obtain solid caustic soda, or I convert the caustic soda into carbonate of soda
by causing it to absorb carbonic acid, and then evaporate to obtain dry
carbonate of soda, or crystals of soda. The metallic sulphates which I use
for decomposing common salt, or for producing sulphuric acid and metallic
oxide, are the sulphates of copper and of zine; and the metallic sulphurets
which I use for producing sulphuric acid and metallic oxide are the sulphurets
of copper and of zinc; and the metallic oxides which I use for decomposing
hydro sulphuret of soda are the deutoxide of copper and the oxide of zinc.
I will now particularly describe the processes by which I apply my
Invention to the manufacture of soda and its carbonate. When I use
sulphuric acid (obtained as herein described) to decompose common salt
and produce sulphate of soda, I effect this decomposition by some of
the means in ordinary use for that purpose. When I use sulphate of
copper to decompose common salt, I take a solution containing thus sulphate,
and having ascertained the quantity of sulphuric acid which it contains, by
testing an aliquot part with muriate of barytes, I add common salt until
the solution contains five per cent. more salt than is equivalent to the
sulphuric acid, and I digest these together. I thus obtain a solution containing
sulphate of sola and muriate of copper. I then evaporate the solution and
separate a great part of the sulphate of soda as small crystals, and I wash

page_text: these crystals with water to separate muriate of copper therefrom, and after
they have been thus washed I dissolve the crystals, and precipitate any copper
contained in the solution by means of metallic iron, or of a solution of hydro
sulphuret of soda. I then evaporate the solution, and thus obtain sulphate
of soda, suitable to be used for the manufacture of soda.
After I have
separated sulphate of soda from the muriate of copper, I decompose the
muriate by means of metallic iron, or of lime. If I use iron for this purpose,
I introduce it into the solution, and I obtain copper as a precipitate and a
solution of muriate of iron. If I use lime, I prepare a fine milk of lime, and
I add this gradually to the solution of muriate of copper (and agitate the
mixture) until the copper is thrown down as a hydrated deutoxide of copper;
I then introduce the mixture into a reverberatory furnace and drive off the
water by heat; I thus obtain dry deutoxide of copper, mixed with chloride
of calcium, and I separate them by washing the mixture with water, and thus
obtain deutoxide of copper suitable for decomposing hydro sulphuret of soda
and producing soda. Instead of separating the sulphate of soda and muriate
of copper in the manner above described I sometimes add to the solution
containing these salts metallic copper in a state of precipitate, or otherwise
finely divided, and then apply heat to this mixture until the greater part of
the muriate of copper is converted into sub chloride of copper, and falls to the
bottom of the vessels containing the mixture. 1 then draw off the solution
and separate the copper which remains therein by means of iron, or of
bydro sulphuret of soda, and I afterwards evaporate the solution, and thus
obtain sulphate of soda suitable for the manufacture of soda. When I have
obtained sub chloride of copper, as above described, I wash it with water,
and separate sulphate of soda therefrom; I then decompose the sub chloride
by means of iron or lime. The sub chloride remains mixed with water;
and if I use iron for this purpose, I introduce it into the mixture of sub
chloride and water, and I obtain copper as a precipitate and a solution of
muriate of iron. If I use lime to decompose the sub chloride of copper,
prepare a fine milk of lime, and I add this gradually to the mixture of
sub chloride and water (and agitate the mixture) until the sub chloride is
decomposed; I then introduce the mixture into a reverberatory furnace having
a current of atmospheric air passing through it, and I drive off the water by
heat. I thus obtain dry deutoxide of copper, mixed with chloride of calcium,
and I separate them by washing the mixture with water, and thus obtain
deutoxide of copper suitable to be used for decomposing hydro sulphate of soda
and producing soda. I also obtain deutoxide of copper (suitable to be used for
decomposing hydro sulphuret of soda and producing soda) from precipitated

page_text: copper, obtained by the means herein-before mentioned, by putting it into a
reverberatory furnace, and exposing it to heat and a current of atmospheric air.
When I use sulphate of zinc to decompose common salt I take a solution
containing this sulphate, and having ascertained the quantity of sulphuric acid
which it contains, by testing an aliquot part with muriate of barytes, I add
common salt until the solution contains five per cent. more salt than is
equivalent to the sulphuric acid, and I digest these together. I thus obtain
a solution containing sulphate of soda and muriate of zine, and I separate
sulphate of soda from the muriate by the means herein-before described for
separating sulphate of soda from muriate of copper, and I precipitate any
zinc contained in the solution of sulphate of soda by means of hydro
sulphuret of soda; I then evaporate the solution and obtain sulphate of
soda suitable to be used for the manufacture of soda. After I have
separated sulphate of soda from the muriate of zinc, I decompose the
muriate by means of lime, or steam and heat. If I use lime for this
purpose, I proceed in the same way in all respects as I have herein-
before described for decomposing muriate of copper by means of lime, and
producing deutoxide of copper therefrom, and I thus obtain oxide of zinc,
suitable to be used for decomposing hydro sulphuret of soda, and producing
soda. If I use steam and heat to decompose the muriate of zinc, I introduce
the solution of this muriate into a furnace, and evaporate it to dryness, and
thus produce chloride of zinc; I then increase the heat of the furnace, and
cause a current of steam to pass over the chloride, and I rake the chloride
in order to assist the action of the heat and steam. Muriatic acid is thus
driven off, and I obtain oxide of zine; but I have found that this oxide is
still mixed with some chloride of zinc, and I therefore wash this mixture with
water, and thus obtain oxide of zinc, suitable to be used for decomposing
bydro sulphuret of soda and producing soda. When I have obtained the
solution containing sulphate of soda and muriate of zinc, by the means herein-
before mentioned for that purpose, I sometimes introduce it into a furnace,
which I call a " distilling furnace," and which is herein-after described, and
I drive off the water and thus convert the muriate of zinc into chloride; I
then increase the heat of the furnace to a degree sufficient to cause the
chloride to volatilize, and I conduct the vapour thus produced into a receiver
and condense it. The residuum in the furnace contains sulphate of soda,
oxide of zinc, and muriate or sulphate of zinc. I digest this residuum with
water, and thus dissolve the sulphate of soda and sulphate of muriate of
zine; the oxide remains undissolved. I then precipitate any zinc contained
in the solution by means of hydro sulphuret of soda, and afterwards evapo-

page_text: rate the solution, and thus obtain sulphate of soda suitable to be used for
manufacturing soda. I dissolve the condensed chloride of zinc collected in
the receiver herein-before mentioned, and thus obtain a solution of muriate
of zinc; I then decompose the muriate by means of lime, in the same manner
as I have herein-before described for decomposing muriate of copper by
means of lime, and I thus obtain oxide of zinc, suitable to be used for de-
composing hydro sulphuret of soda, and producing soda. The dry sulphate of
soda obtained by the means herein-before mentioned for that purpose may be
decomposed by mixing it with powdered coke or coal, in the proportion by
weight of about three parts of sulphate to one part of coke or coal, and fluxing
this mixture in a reverberatory furnace, similar to the furnaces in general use
for decomposing sulphate of soda in manufacturing carbonate of soda; but I
decompose sulphate of soda in a reverberatory furnace of greater length and
less width than the furnaces usually employed in the manufacture of carbonate
of soda, and having an inclining instead of an horizontal floor. I prefer that
the floor of this furnace should be about twenty-five feet in length. For
the purpose of reference I call this furnace "the decomposing furnace. " I
construct this furnace with a fireplace at each end, and an opening
through the arch near the centre, communicating with a chimney, so that
the flames from the fires pass over the materials on the floor of the furnace,
and through the opening into the chimney. An opening is also made in one
side of the furnace at the lower end to provide for the product of the
decomposition running out. I place coke or coal in small pieces upon the
floor of this furnace, so as to form a bed three or four inches deep (but I
prefer to use coke), and I then introduce sulphate of soda near the upper end
of the furnace. The sulphate becomes fluxed, and then percolates through
the material on the floor of the furnace, whereby it is decomposed, and after
flowing to the lower end of the furnace the product escapes through the
opening in the side. During this operation I add coal or coke from time to
time, as often as may be necessary, to keep a bed of such material about
three inches deep upon the floor of the furnace, and I keep such a quantity
of sulphate of soda near the upper end of the furnace as will provide for
fluxed sulphate constantly percolating through the material on the floor of
the furnace. By decomposing sulphate of soda I obtain sulphuret of sodium,
mixed with caustic soda, carbonate of soda, and other matters. I dissolve
this product by lixiviating it with water, and thus obtain a solution containing
hydro sulphuret of soda and some sulphuret of soda. I cause this solution
to be boiled in boilers which are fixed in brickwork in such manner as to
protect the lower part of them from the direct action of the heat, which is

page_text: employed to boil the solution.
When the solution boils I add to it a
mixture of deutoxide of copper and metallic copper, or of oxide of zinc and
metallic zine (the metal being in a state of fine division), in the proportion
of twenty parts (by weight) of deutoxide of copper, or oxide of zinc, to one
part (by weight) of metallic copper, or metallic zinc. My object in using
these metals is to decompose the sulphuret of soda, and it is necessary that
they should be in a state of fine division. I continue the boiling, and add
the mixture of oxide and metal gradually until the hydro sulphuret of soda
and the sulphuret of soda are completely decomposed, and I stir the contents
of the boiler to promote this decomposition. I ascertain when such decom-
position is effected by inserting metallic silver into the liquid, and the de-
composition is complete if such silver is not stained or discoloured. The
products of this decomposition are caustic soda in solution, and an insoluble
metallic sulphuret; and in order to separate these I allow the sulphuret to
subside, and I then draw off the solution and wash the sulphuret with water
to extract a further quantity of soda. I thus obtain caustic soda in solution
suitable to be employed for manufacturing soap and other purposes, but the
solution may be evaporated until it becomes sufliciently strong to yield solid
caustic soda. Dry carbonate of soda, or crystallized carbonate of soda, may
also be manufactured from this solution by causing it to absorb carbonic
acid, procured by the combustion of coke or any other suitable process, and
afterwards treating the solution of carbonate of soda (so obtained) in the
usual manner to produce dry carbonate of soda, or crystals of soda, as the
case may be.
I will now describe the processes by which I obtain metallic sulphates,
sulphuric acid, and metallic oxides (suitable to be used in the operations
herein-before described) from the sulphurets of copper and zinc, which [
obtain by the processes herein-before mentioned. When I wish to produce
metallic sulphate I use the furnace herein-after described, and called "the
sulphating furnace." I heat this furnace until it has attained a tempera-
ture of about four hundred degrees of Fahrenheit's thermometer, and then
put sulphuret of copper or of zine into it, and cause a current of atmospheric
air to pass through it. I keep the furnace heated, and rake the sulphuret
occasionally, and break any lumps which may be formed to facilitate the action
upon the sulphuret, and at the end of about twelve hours the greater part of
the sulphuret is converted into sulphate. For the purpose of reference I call
this operation "the sulphating operation." When I propose to use the
sulphate obtained by this operation for the purpose of decomposing common
salt, and therchy producing sulphate of soda, I lixiviate the product of the

page_text: "
sulphating operation" with water, and thus obtain a solution of sulphate of
The
copper or of zinc (as the case may be) suitable for such purpose.
residuum of this lixiviation contains oxide and sulphuret. If the oxide pre-
dominate I use it to decompose hydro sulphuret of soda, in the manner
herein before mentioned for that purpose; but if the sulphuret predominate,
I return the residuum into the "sulphating furnace" to convert the sulphuret
into sulphate. When I use the sulphate obtained by the "sulphating opera-
tion" for making sulphuric acid, I put the product of such operation into the
furnace herein-after described, and called the "distilling furnace," and I cause
such product to be heated to a bright red heat, by which sulphuric acid is
driven off. During this operation a small current of atmospheric air passes
through the "distilling furnace," and the gases produced pass through a pipe
provided for that purpose into a condensing apparatus, similar to the leaden
chambers now in general use in the manufacture of sulphuric acid. I find
that a portion of the sulphuric acid which is driven off in the "distilling
furnace" is decomposed into sulphurous acid and oxygen gas, and I therefore
introduce nitrous acid vapour into the condensing apparatus, and thus recon-
vert the sulphurous acid into sulphuric acid. For the purpose of reference I
call the operation hererein-before described, and which is conducted in the
"distilling furnace," the "distilling operation." In the process herein-before
described for obtaining sulphuric acid from sulphuret of copper or sulphuret of
zine, the sulphuret employed is converted into sulphate in the first instance;
but I also obtain sulphuric acid by the use of either of these sulphurets,
without previously converting it into sulphate. For this purpose I dry the
sulphuret by any convenient means, and then put it into the furnace herein-
after described, and called the "furnace of combustion," and I heat the
sulphuret to redness. During this operation a current of atmospheric air
passes through the furnace, and sulphurous acid gas is produced by the action
of the atmospheric air on the sulphuret, and I rake the sulphuret occasionally
to promote such action. The gas passes off through a pipe provided for that
purpose into a leaden chamber, similar to those generally used in the manu-
facture of sulphuric acid, and I convert the sulphurous acid thus obtained into
sulphuric acid by means of nitrous acid vapour and the atmospheric air which
is passed through the "furnace of combution." For the purpose of reference
5 I call the operation herein-before described, and which is conducted in the
"furnace of combustion," the "operation of combustion." The residuum
which remains in the "distilling furnace" and the "furnace of combustion,"
(after the distilling operation" and the "operation of combustion" have been
completed) cont: ins oxide of copper or oxide of zinc (as the case may be),
86

page_text: sulphate and sub sulphate; and by the process herein-after described for that
purpose I render such residuum suitable for decomposing hydro sulphuret of
soda and producing soda. In the operations which I have already described
for obtaining sulphuric acid I use one of the metallic sulphates, or one of the
metallic sulphurets herein-before mentioned alone, but I also obtain sulphuric
acid by using a mixture of sulphuret of copper and sulphate of copper, or
sulphuret of zine and sulphate of zinc. For this purpose I mix the sulphuret
and sulphate together in such proportions that the mixture may contain five parts
by weight of dry sulphate for one part by weight of sulphuret, or thereabouts,
and I break any lumps that may be present in order that the whole may be
well mixed together; I then put the mixture into the "furnace of com-
bustion" and heat it to redness. By these means sulphurous acid is produced
and passes off, and I convert it into sulphuric acid in the same manner as the
sulphurous acid which is produced in the "operation of combustion" herein-
before,described. The residuum which remains in the "furnace of combus-
tion" after this operation contains deutoxide of copper or oxide of zinc (as the
case may be), and this residuum, as also the residuum remaining from the
distilling operation" and the "operation of combustion," herein-before de-
scribed, require to be freed from sulphate and sub sulphate, in order to render
them suitable to be used for decomposing hydro sulphuret of soda and
producing soda. For this purpose I wash them with water and thus dissolve
the sulphate contained therein, and I then extract such sulphate by drawing
off the solution. I then add to the residuum hydro sulphuret of soda in
sufficient quantity to decompose the sulphate which it contains, and I thus
obtain a solution containing sulphate of soda. I evaporate this solution
and then obtain sulphate of soda in a dry state. I have described the pro-
cesses by which I convert the sulphurets of copper and zinc (obtained by
decomposing hydro sulphuret of soda by means of deutoxide of copper or
oxide of zinc) into sulphates of these metals, and by which I obtain sulphuric
acid from these sulphates, and by which I apply these sulphates and the
sulphuric acid so obtained to the manufacture of sulphate of soda; but the
same processes may also be used to obtain sulphates from native sulphurets of
copper and zinc, and the sulphates thus obtained may be applied to the manu-
facture of sulphate of soda in the manner herein-before described for that
purpose. I would observe, however, that when these native sulphurets are
employed it is necessary to reduce them to powder before they are subjected
to the "sulphating operation."
.
I will now describe my Invention as I apply it to the manufacture of potash
and its carbonate. The salts of potash which I use are the muriate, the nitrate,

page_text: and the sulphate of potash. When I use the muriate, I apply my Invention in
every respect in the same manner for producing potash and its carbonate by
the use of this salt as I have herein-before described for producing soda and
its carbonate by the use of common salt, which is known to be muriate of soda.
When I use the nitrate of potash, I decompose it by sulphuric acid obtained as
herein-before mentioned, and I thus obtain sulphate of potash and nitric acid;
and I use the sulphate of potash as also any other sulphate of potash for
producing potash and its carbonate in every respect in the same manner as
I have herein-before described for producing soda and its carbonates, by the
use of sulphate of soda.
I will now describe the construction of the several furnaces herein-before
mentioned, which I call the "decomposing furnace," the "sulphating furnace,"
the "distilling furnace," and the "furnace of combustion," reference being had
to the Drawings hereunto annexed. Figures 1 and 2 represent the "decom-
posing furnace," Figure 1 being a transverse vertical section of such furnace,
and Figure 2 being a longitudinal vertical section of the same, this latter
section being taken in the line a, b, of Figure 1, and the section Figure 1
being taken in the line a, b, of Figure 2. In these Figures the same letters
are used to denote the corresponding parts of the furnace. A, A, are the ash
pits; B, B, the grates; C, C, the fireplaces; D, D, the arch; E, E, the
bridges; F, F, the fire doors; G, the flue communicating with the chimney;
H, H, doors through which coke or coal is introduced on the floor of the
furnace; H, the door through which the sulphate of soda or the sulphate of
potash is introduced; I, 1, the floor of the furnace, which is inclined so as to
form an angle of about four degrees with the horizontal line L, L; K, K, the
brickwork of the furnace; N, the opening through which the product of the
operation flows. The arrows denote the current of the flames from the
fireplaces.
Figures 3 and 4 represent the distilling furnace, Figure 3 being a trans-
verse vertical section of such furnace, and Figure 4 being a longitudinal
vertical section of the same, this latter section being taken in the line a, b,
of Figure 3, and the section Figure 3 being taken in the line a, b, of Figure 4.
The same letters are used in both Figures to denote the corresponding parts
of the furnace. A is the ash pit; B, the grate; C, the fireplace; D, an
arch, forming the bottom of the distilling chamber; E, an arch, forming
the top of the distilling chamber; J, the distilling chamber; F, F, the fluo
by which the flame passes under the lower arch and over the upper arch,
and arrives at the flue G, which communicates with the chimney; I, I, brick-
work, closing the ends of the distilling chamber J; K, a pipe for con-

page_text: ducting the vapours produced by the "distilling operation" to the condensing
apparatus. This pipe is formed of double walls of brickwork, having an inter
stice between them, which is filled with fine sand or ground fire clay to prevent
the escape of gas. II, the door for charging the furnace. This door does not
close tight, and therefore admits a current of air to pass into the chamber.
M, M, the brickwork of the furnace; N, the upper arch. The arrows denote the
current of the flame from the fireplace. I construct the "sulphating furnace"
in the same way as the "distilling furnace," except that I make the chamber J
about twice as long as the chamber of the "distilling furnace," and I have two
doors for charging such chamber.
nacc.
Figures 5 and 6 represent the "furnace of combustion," Figure 5 being a
transverse vertical section of such furnace, and Figure 6 a longitudinal vertical
section of the same, this latter section being taken in the line a, b, of Figure 5,
and the section Figure 5 being taken in the line a, b, of Figure 6.
The same
letters are used in these Figures to denote the corresponding parts of the fur-
A is the ash pit; B, the grate; C, the fireplace; D, an arch, forming
the bottom of the lower chamber of combustion; E, an arch, forming the top
of the lower chamber of combustion; F, the lower chamber of combustion;
H is an arch forming the bottom of the upper chamber of combustion; I, an
arch forming the top of the upper chamber of combustion; J is the upper
chamber of combustion; M, M, are flues in the brickwork of the side of
the furnace to conduct the flame after it has passed under the arch D to the
space marked G, between the arches E and II; and N, N, are flues to con-
duct the flame to the space marked K above the arch I, whence it escapes.
into the chimney by the flue O. The flues M, M, and N, N, are denoted by
dotted lines, and the arrows not marked with an asterick denote the current of
the flame. T, T, are walls closing the ends of the chambers F and J, except as
to an opening left in each wall to provide for the passage of gas into the pipe S.
L is the upper arch, and P, P, the brickwork of the furnace. The chambers
Fand J are provided with iron doors at the front marked Q, Q, through which
the charges of material are introduced, and which admit atmospheric air to
pass through the chambers during the operation. S is a pipe communicating
with a leaden chamber. The arrows marked with astericks denote the current
of the gas. For the inside of all these furnaces I use the best fire bricks, and
I take great care to have the brickwork well put together. The furnaces
should be well supported with iron plates and bars in the usual manner, and I
surround such of the flues as are nearly in contact with the chambers with
coatings of fine sand, or ground fire clay, to prevent the escape of gas. A
coating is shown only in Figure 4, as surrounding the flue marked K in such

page_text: Figure; but I use a similar coating to surround the flues M, N, and S, in
Figures 5 and 6.
In this my Specification I have described the apparatus which I consider
most suitable for effecting my Invention, but I do not confine myself to the
use of any particular apparatus, nor do I claim any apparatus as my Invention
And I have mentioned certain proportions of materials which I prefer to use in
effecting my Invention, but I do not confine myself to use these materials in
the exact proportions herein mentioned. I claim as my Invention a combina-
tion of processes by which potash or soda may be produced by the action of
deutoxide of copper or oxide of zinc (obtained from the sulphuret of copper or
the sulphuret of zinc. produced by the use of my Invention), or hydro sulphuret
of potash, or hydro sulphuret of soda; and the metallic sulphuret produced by
this action is either converted into deutoxide of copper or oxide of zine, suitable
to be applied to act on hydro sulphuret of potash or hydro sulphuret of soda; and
the sulphur contained in the sulphuret is converted into sulphuric acid, suitable
to be used for decomposing muriate or nitrate of potash or common salt, for
the purpose of manufacturing potash or soda; or otherwise the metallic sul-
phuret produced is converted into sulphate of copper or sulphate of zinc. And
this sulphate is used to decompose muriate of potash or common salt, and pro-
duce sulphate of potash or sulphate of soda, and also deutoxide of copper or
oxide of zinc, suitable for decomposing hydro sulphuret of potash or hydro
sulphuret of soda to produce potash or soda. I also claim as my Invention
the manufacture of carbonate of potash and carbonate of soda by means of the
potash and soda obtained by such combination of processes as herein-before
mentioned. I also claim as my Invention the application in the manufacture
of potash or soda, or their carbonates, of sulphate of potash or sulphate of
soda, obtained by decomposing muriate of potash or common salt by means
of sulphate of copper or sulphate of zinc, obtained from the sulphurets of
these metals. And I also claim as my Invention an improved mode of decom-
posing sulphate of potash and sulphate of soda for obtaining bydro sulphuret
of potash or hydro sulphuret of soda, to be used in the manufacture of
potash or soda, or their carbonates, which improved mode consists in decom-
posing sulphate of potash or sulphate of soda, and thus producing sulphuret
of potassium or sulphuret of sodium, by causing such sulphate in a state of
fusion to flow gradually through a bed of coke or coal.
In witness whereof, I, the said William Hunt, have hereunto set my
hand and seal, this Eighteenth day of July, in the year of our Lord
One thousand eight hundred and forty.
WILLIAM (L.S.) HUNT.

page_text: Extraordinary in Chancery.
AND BE IT REMEMBERED, that on the same Eighteenth day of July,
in the year above mentioned, the aforesaid William Hunt came before our
Lady the Queen in Her Chancery, and acknowledged the Specification aforesaid,
and all and every thing therein contained, in form above written. And also
the Specification aforesaid was stamped according to the tenor of the Statute
in that case made and provided.
Inrolled the Twenty-first day of July, in the year above written.