IMPROVEMENTS IN THE MANUFACTURE OF CARBONATE OF SODA. AND IN APPARATUS TO BE EMPLOYED IN THE SAID MANUFACTURE: ALSO IN UTILIZING WASTE PRODUCTS OBTAINED IN THE SAID MANUFACTURE
Year: 1860

page_text: LETTERS PATENT to William Hunt, of Tipton, in the County of Stafford
Manufacturing Chemist, for the Invention of "IMPROVEMENTS IN THE
MANUFACTURE OF CARBONATE OF SODA. AND IN APPARATUS TO BE EMPLOYED
IN THE SAID MANUFACTURE: ALSO IN UTILIZING WASTE PRODUCTS OBTAINED IN
THE SAID MANUFACTURE,"
Sealed the 6th July 1860, and dated the 5th May 1860.
PROVISIONAL SPECIFICATION left by the said William funt at the
Office of the Commissioners of Patents, with his Petition, on the 5th
May 1860.
I, WILLIAM HUNT, of Tipton, in the County of Stafford, Manufacturing
Chemist, do hereby declare the nature of the said Invention for "IMPROVE-
MENTS IN THE MANUFACTURE OF CARBONATE OF SODA. AN. IN APPARATUS TO BE
EMPLOYED IN THE SAID MANUFACTURE: ALSO IN UTILIZING WASTE PRODUCTS
OBTAINED IN THE SAID MANUFACTURE," to be as follows:-
My improvements in the manufacture of carbonate of soda consist in
manufacturing it by the following process, that is to say: I mix salt
cake or sulphate of soda with coal or coke, in the proportion of about four
I heat
parts by weight of the former to three parts of the latter.
the mixture in a reverberatory furnace to a temperature sufficient to fuse
it; there is thereby produced sulphuret of sodium mixed with coke.
When cold, I break the said sulphuret of sodium into lumps of three or

page_text: four inches in diameter, and place the said lumps in a chamber or tower,
constructed in the manner herein-after described, and which I will call
the carbonating chamber or tower. I pass into the said carbonating
chamber, and among the lumps of sulphuret of sodium, pure or nearly
pure carbonic acid gas, and also a small current of steam. The said
steam moistens the sulphuret of sodium, and when so moistened, the
said sulphuret is decomposed by the carbonic acid gas, carbonate of soda
being formed, and sulphuretted hydrogen liberated. The lumps of
carbonate of soda mixed with small pieces of coke, on being
withdrawn from the carbonating chamber, are treated with
hot water, whereby the carbonate of soda is dissolved out, and
may be obtained, by evaporation, in crystals or as soda ash.
The sulphuretted hydrogen which escapes from the carbonating
chamber is utilized in the manner herein-after explained, and
the small pieces of coke from which the carbonate of soda has been
dissolved are used with a little fresh coal slack to decompose a further
quantity of salt cake. The carbonating chamber or tower is made of iron
or brick, and the sulphuret of sodium is fed into it through a hole at
the top, which can be closely stopped at pleasure. The sulphuretted
hydrogen escapes by another hole at the top. The carbonate of soda
formed is removed at bottom, through a hole, which can also be stopped
at pleasure. As the lumps of sulphuret of sodium while being car-
bonated are apt to stick together, it is necessary to separate or break
them, so that they may properly descend in the chamber when the bottom
portions are removed. To effect this, I introduce vertical rods passing
through gas-tight holes into the chamber. These rods have lateral arms
or branches, and by lifting the said rods up and down occasionally, the
lumps are kept separate. The carbonic acid which I employ is made by
heating limestone or carbonate of lime.
I utilize the sulphuretted hydrogen which escapes from the car-
bonating chamber by burning it, and thereby producing sulphurous acid,
which is converted into sulphuric acid in the usual way. In order to
effect the perfect combustion of the sulphur of the sulphuretted hydrogen,
I conduct the gas into a small chamber built, by preference, with fire-
brick. The said chamber is filled or partly filled with pebbles, or broken
brick, or other material which will bear heat, and is not acted on by
sulphuretted hydrogen or sulphurous acid; or I fill the said chamber with
lumps of oxide of iron or maganese. The sulphuretted bydrogen is
introduced at the bottom of the chamber, together with atmospheric

page_text: air, which latter passes through a slit, the size of which may be regulated
at pleasure. The gas is ignited, and in passing through the pebbles,
makes them red hot. The heat of the pebbles promotes the perfect
combustion of the gas, and rekindles it, if from irregularity in its supply
the flame goes out. When oxide of iron or manganese is employed,
any excess of sulphur is retained should there be a temporary deficiency
of air, and again given off and burned, when the quantity of air becomes
relatively greater. The sulphuretted hydrogen given off when a solution
of sulphuret of sodium is decomposed by carbonic acid gas may be
utilized in the same way. Any free sulphur which may be mixed with
the carbonate of soda, as it comes from the carbonating chamber may
be recovered by heating the said carbonate in a close vessel.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Hunt, in the Great Seal Patent Office on the
2nd November 1860.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
HUNT, of Tipton, in the County of Stafford, Manufacturing Chemist,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day of May, in the year of our Lord One
thousand eight hundred and sixty, in the twenty-third year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the
said William Hunt, Her special licence that I, the said William Hunt,
my executors, administrators, and assigns, or such others as I, the said
William Hunt, my executors, administrators, and assigns, should at any
time agree with, and no others, from time to time and at all times there-
after 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 "IM.
PROVEMENTS IN THE MANUFACTURE OF CARBONATE OF SODA, AND IN APPARATUS TO
BE EMPLOYED IN THE SAID MANUFACTURE: ALSO IN UTILIZING WASTE PRODUCTS
OBTAINED IN THE SAID MANUFACTURE," upon the condition (amongst others) that
I, the said William Hunt, my executors or administrators, by an instru-
ment in writing under my, or their, or one of their hands and seals,
should particularly describe and ascertain the nature of the said Inven-
tion, 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

page_text: months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said William Hunt, 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:-
My improvements in the manufacture of carbonate of soda consist in
manufacturing it by the following process, that is to say :-I mix salt cake
or sulphate of soda with coal or coke, in the proportion of about four
parts by weight of the former to three parts of the latter. I heat the
mixture in a reverberatory furnace to a temperature sufficient to fuse
it. There is thereby produced sulphuret of sodium mixed with coke.
When cold, 1 break the said sulphuret of sodium into lumps of three or
four inches in diameter, and place the said lumps in the cisterns or
vessels herein-after described and illustrated in the accompanying
Drawing, and which I will herein-after call the carbonating cisterns or
vessels. I pass into the said carbonating cisterns or vessels and among
the lumps of sulphuret of sodium, pure or nearly pure carbonic acid gas,
and also a small current of steam. The said steam moistens the sulphuret
of sodium, and when so moistened, the said sulphuret is decomposed
by the carbonic acid gas, carbonate of soda being formed and sulphuretted
hydrogen liberated, and some free sulphur which remains amongst the
carbonate of soda and coke. The lumps of carbonate of soda, mixed
with small pieces of coke and free sulphur, are treated with hot water
in the carbonating cisterns or vessels, or removed to ordinary vats for
that purpose. The carbonate of soda is thereby dissolved out and may
be obtained by evaporation in crystals or as soda ash. The sulphuretted
hydrogen which escapes from the carbonating cisterns or vessels is
utilized in the manner herein-after explained, and the small pieces of
coke from which the carbonate of soda has been dissolved are used with
a little fresh coal, slack, or coke, to decompose a further quantity of
salt cake. I also similariy utilize the coke obtained when the sulphuret
of sodium is dissolved from the said coke before it is carbonated, irrespec-
tive of the method by which the sulphuret of sodium is manufactured.
The carbonic acid which I employ is made by heating limestone or
carbonate of lime or chalk, in the manner herein-after explained.
I utilize the sulphuretted hydrogen which escapes from the carbonating
cisterns or vessels by burning it, and thereby producing sulphurous acid,
which is converted into sulphuric acid in the usual way. In order to

page_text: effect the perfect combustion of the sulphur of the sulphuretted hydrogen,
I conduct the gas into a small chamber, built by preference of fire-brick.
The said chamber is filled or partly filled with pebbles or broken brick,
or other material which will bear heat, and is not acted on by
sulphuretted hydrogen or sulphurous acid. The sulphuretted hydrogen
is introduced at the bottom of the chamber, together with atmospheric
air, which latter passes through a slit, the size of which may be regulated
at pleasure. The gas is ignited, and in passing through the pebbles
makes them red hot. The heat of the pebbles promotes the perfect com-
bustion of the gas, and rekindles it, if from irregularity in its supply
the flame goes out. The sulphuretted hydrogen given off when a solution
of sulphuret of sodium is decomposed by carbonic acid gas, or obtained
by any other process, may be utilized in the same way. Any free sulphur
which may be mixed with the carbonate of soda as it comes from the
carbonating cistern or vessel may be recovered by heating the said
carbonate in a close vessel.
The free sulphur which remains among the coke after dissolving out
the carbonate of soda I utilize in the following manner:-The sulphur
being in a flocculent condition, it may be washed from the coke before
the latter is removed from the vessel or vat by splashing a quantity of
water upon it. By afterwards allowing the water so splashed on the
coke to run freely from the vessel or vat, nearly all the sulphur will be
carried off in the water, the said sulphur being mixed with some little
carthy matter and fine coke. The said water, carrying with it the carthy
matter, sulphur, and coke, as described, is conducted to a tank or vessel
at the bottom of which tank the earthy matter and sulphur are deposited,
while the light particles of coke float upon the surface of the water, and
may be skimmed off. The sulphur and earthy matter are removed from the
tank from time to time, and the sulphur may be distilled or burnt, and
the sulphurous acid thus produced be applied to the manufacture of
sulphuric acid or other purpose. The coke residuum is then in a fit
state to be re-used, and the earthy matter is thrown away. Or the whole
of the coke containing the free sulphur may be heated in an earthen
retort, and the sulphur distilled off and used for making sulphuric acid,
or for other purpose. The coke remaining in the retort may be re-used
for decomposing a further quantity of sulphate of soda, as herein-before
explained.
The apparatus by which I carry my Invention into effect is represented

page_text: Figure 1 represents in vertical section, the furnace and apparatus by
which I generate carbonic acid gas; and Figure 2 represents the same
in plan; Figure 3 represents in vertical section, the carbonating cisterns
or vessels, and the chamber in which the evolved sulphuretted hydrogen
is burned after having been mixed with air; and Figure 4 represents the
same in plan.
In Figures 1 and 2, a, a, represent vertical tubular vessels or retorts
made of fire-clay or iron, around which the flame and heated air from
the furnaces b, b, pass. The air passes from the furnaces by the open-
ings c, c. The tops of the retorts are closed by means of covers, one of
which is shown in plan in Figure 5, and in vertical section in Figure 6.
The limestone or chalk is charged into the retorts through the openings
d, d, which openings are closed by covers e, e, made tight with a sand
joint or lute, and the carbonic acid gas driven off from the limestone or
chalk is conducted by means of syphon-shaped tubes fitted by a sand
lute on the covers f, f. The burnt lime is removed from the retorts by
openings at their bottoms, and during the charging and drawing of the
lime from the said retorts, the siphon tube should be removed, and its
end temporarily closed, so as to prevent atmospheric air entering the
carbonating vessels. The carbonic acid passes from the retorts to the
main pipe x, and enters the carbonating cisterns or vessels g, h, i,
Figures 3 and 4 at the bottom openings marked k, l, m, underneath
the perforated false bottoms n, o, 7, on which the sulphuret of sodium
is supported. Steam is at the same time introduced into each of the
carbonating cisterns or vessels at the openings q, r, s, in the same
direction as the carbonic acid, the said steam being obtained from a
steam boiler and conducted to the cisterns or vessels g, h, i, by means
of lead or other piping. The carbonic acid gas passes out of the top of
the first vessel by means of the curved pipe t into the bottom of the
second vessel h, and from the top of the second vessel by means of
the curved pipe into the bottom of the third vessel i, from whence it
passes by the pipe into the chimney w. The several junctions of the
pipes with the carbonating vessels or chambers are made tight by means
of water joints in the manner well understood. After the contents of
the first vessel have been sufficiently carbonated (which is ascertained
by taking a lump of the carbonated material out from time to time, when
the lump is broken and carbonated crystals are formed inside, it may
be considered finished), the gas is shut off from the said vessel and passed
direct into the second vessel, and the first vessel having been recharged

page_text: with sulphuret of sodium the gas is made to pass through it last. Each
vessel is thus made in turn to be the first of the series. These changes
in the direction of the gas are made by means if the pipes x, y and z.
When the series of carbonating vessels is first set into operation, the
carbonic acid passes from the pipe at 1 into the vessel g at k, and
out of the vessel g att into the pipe L, and thence through the vessels h
and i into the chimney w.. When the first vessel has been fully
carbonated, and is recharged, the gas is made to take this course,
namely, from the pipe a, into the vessel hat 2, and from the vessel i
through the pipe y into the vessel g, and from the said vessel g into
the pipe z. By means of the pipes and openings represented, the gas
can be passed in any desired order through the vessels g, h and i. The
vessels 9. h and i. may either be made of brick or of iron. A series of
three, four, or other number of the carbonating vessels may be employed.
The mixture of carbonate of soda and carbonaceous matter may either
be lixiviated with water in the said vessels g, h, i, so as to dissolve the
carbonate of soda from the carbonaceous matter in the said vessels, the
carbonaceous matter being afterwards removed to be re-used, or the
mixture may be removed from the vessels g, h, i, and lixiviated with
water in other vessels or vats. When I lixiviate in the same vessels as I
carbonate in, I use a greater number of vessels for carbonating, as some
of the vessels would be in use as lixiviating vessels, while others were
being used for carbonating, and I provide all the carbonating vessels
with means for running off the liquor as in ordinary vats without interfer-
ing with the arrangements for supplying the gas as required. As the
sulphuretted hydrogen, which the carbonic acid liberates from the
sulphuret of sodium in the vessels g, h, i, passes to the chimney or
chamber w, it is mixed with atmospheric air, which enters the slit or
opening 3, and which said slit or opening may be partially covered with
a plate or damper to regulate the quantity of air entering. The
chimney or chamber w is provided with two holes to look through, one
above the stratum of pebbles 4 and the other below; the burning of
the gas can be observed from time to time through these holes. The
gaseous mixture is ignited underneath the stratum of pebbles or broken
brick 4, which becomes red hot and rekindles the gas, if from a tem-
porary stoppage or otherwise the said gas is extinguished. The
sulphurous acid gas produced by the combustion passes into an ordinary
oil of vitriol chamber to be converted into sulphuric acid in the ordinary
manner. The sulphuretted hydrogen obtained when sulphuret of
sodium in solution is treated with carbonic acid, may be burned in the

page_text: way described, and sulphuric acid made therefrom. I prefer to make
the combustion chimney or chamber w, of brick, lined with fire-brick,
and of sufficient size to create draught enough to draw the sulphuretted
hydrogen from the carbonating vessels.
Having now described the nature of my Invention and the manner of
carrying the same into effect, I wish it to be understood that I do not
limit myself to the precise details herein described and represented as
the same may be varied without departing from the nature of my
Invention; but I claim as my Invention:-
Firstly, manufacturing carbonate of soda by exposing sulphuret of
sodium to a current of carbonic acid gas obtained by heating limestone
or chalk in close vessels or retorts without the aid of steam.
Secondly, the general arrangement of apparatus to be used in the
manufacture of carbonate of soda herein-before described and illus-
trated in the accompanying Drawings.
Thirdly, the re-use of the carbonaceous matter, which is obtained as
a residuum after dissolving out from it the carbonate of soda with
which it is mixed in the manufacture of carbonate of soda by the process
herein-before described, or obtained as a residuum when the sulphuret
of sodium is dissolved from the said coke before the said sulphuret of
sodium is carbonated, and irrespective of the method by which the
sulphuret of sodium is manufactured.
Fourthly, utilizing the sulphuretted hydrogen obtained as a residual
product in the manufacture of carbonate of soda by mixing the said
sulphuretted hydrogen with atmospheric air, and burning it in the
manner herein-before described to obtain sulphurous acid therefrom,
which sulphurous acid may be made into sulphuric acid in the usual
manner.
Fifthly, utilizing the free sulphur, which occurs as a residuum with
the carbon or coke after the carbonate of soda has been dissolved out as
herein described.
In witness whereof, I, the said William Hunt, have hereunto set
my hand and scal, this First day of November, in the year of our
Lord One thousand eight hundred and sixty.
Witness,
GEORGE SHAW,
WILLIAM HUNT. (I..s.)