CERTAIN IMPROVEMENTS IN PREPARING OR MANUFACTURING SUL- PHURIC ACID,
Year: 1838

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
FOWLER, of Birmingham, in the County of Warwick, Gentleman, send
greeting.
WHEREAS Her present most Excellent Majesty hath granted unto me
Her Letters Patent, sealed at Westminster, the Sixteenth day of October, in
the second year of Her reign, for making, using, exercising, and vending,
within that part of the United Kingdom of Great Britain and Ireland called
England, Her Dominion of Wales, and Town of Berwick-upon-Tweed, my
Invention of "CERTAIN IMPROVEMENTS IN PREPARING OR MANUFACTURING SUL-
PHURIC ACID," subject to the usual proviso, obliging me to describe and ascer-
tain the nature of my said Invention, and in what manner the same is to be
performed, by an instrument in writing under my hand and seal, and to cause
the same to be enrolled in the High Court of Chancery within six calendar
months next after the date of the said Letters Patent.
NOW KNOW YE, that in compliance with the said proviso, I, the said
John Fowler, do hereby describe and ascertain the nature of my said Inven-
tion, and in what manner the same is to be performed, as follows (that is
to say):
-
My improvements consist in preparing or manufacturing sulphuric acid by
the use of sulphur contained in sulphate of soda, sulphate of potash, and
sulphate of lime, and extracted for this purpose by the actions herein-after
specified.
I will first describe the several processes by which I extract sulphur (which
I obtain in combination with hydrogen gas) from sulphate of soda and sul-
phate of potash by the action of hydrogen, whilst these sulphates are being

page_text: decomposed by means of carbon.
I decompose the sulphate which I employ'
whether it be the sulphate of soda or the sulphate of potash, in a retort or
other suitable vessel, by the use of carbon at a high temperature, and during
this decomposition I cause a current of steam, or of hydrogen gas, or of car-
buretted hydrogen gas, to pass through such retort or other vessel. In this pro-
cess the carbon combines with oxygen contained in the sulphate, and produces
carbonic acid, which combines either wholly or in part with the soda or potash
contained in the sulphate employed, and forms carbonate of soda or carbonate
of potash (as the case may be), and sulphuretted hydrogen gas is produced
by the action of the hydrogen contained in the steam or gas upon the
sulphur contained in the sulphate. The apparatus which I prefer to
employ for the decomposition of these sulphates consists of a retort placed
vertically in a suitable furnace, and having at its upper end an aperture
through which the sulphate may be introduced, and a pipe for conveying
off gas, and having at its lower end a pipe by which steam or gas may
be introduced, and an aperture through which the carbonate of soda or
carbonate of potash (as the case may be) may be withdrawn. I introduce
coke in small pieces into the retort until it is nearly full, and I apply a
strong heat until the coke becomes heated to a full red heat; I then
introduce into the retort sulphate of soda or sulphate of potash, and close
the apertures of the retort; after which, I introduce steam, or hydrogen gas,
or carburetted hydrogen gas, and the sulphate as it is fused by the heat flows
over the coke and is decomposed, whilst the steam or gas which I employ
passes through the interstices between the pieces of coke, and furnishes hydro-
gen gas, which combines with the sulphur contained in the sulphate, and
sulphuretted hydrogen gas is produced. This gas passes off through the tube
.at the upper end of the retort, and I collect and apply it as herein-after men-
tioned. It will be understood that the retort is furnished with a lid or cover,
by which I close the aperture at the upper end of it immediately after intro-
ducing the sulphate, and the aperture at the lower end of the retort is furnished
with a stopper, which I remove when I withdraw the carbonate of soda or
carbonate of potash produced by the operation.
;
I will now describe certain processes by which I extract sulphur in com-
bination with hydrogen gas from sulphate of soda or sulphate of potash, and
which consists in converting the sulphate employed into sulphuret of sodium
or sulphuret of potassium (as the case may be), in the first instance, and sub-
sequently extracting sulphur from such sulphuret by the action of carbonic
acid and water. I mix sulphate of soda or sulphate of potash with coke in a
powdered state, in the proportion by weight of six parts of sulphate to one part

page_text: of coke, and I expose the mixture to a red heat. The sulphate is thus con-
verted into sulphuret of sodium or sulphuret of potassium (as the case may be),
and carbonic acid gas is evolved. This operation may be effected either in an
open furnace or in a closed retort, but I prefer to employ a closed retort,
because I can then collect the carbonic acid gas which is evolved, and which
is applicable for the several purposes for which I use carbonic acid gas in the
several processes or operations herein-after mentioned. To facilitate the
decomposition of the sulphuret I break it into small pieces, and when thus
broken I expose it to the joint action of carbonic acid gas and water; by this
action I obtain sulphur in combination with hydrogen gas, and also carbonate
of soda or carbonate of potash (as the case may be).
I will now describe certain processes by which I extract sulphur in combi-
nation with hydrogen gas from sulphate of soda or sulphate of potash, and
which consists in transferring sulphur contained in the sulphate into combi-
nation with iron, and thereby producing sulphuret of iron in the first instance,
and in subsequently extracting sulphur from this sulphuret by the action of
inuriatic acid or sulphuric acid. I mix sulphate of soda or sulphate of potash
with powdered coke and iron, the iron being either in a metallic state or in
the state of oxide, in the proportion by weight of twelve parts of sulphate, four
parts of powdered coke, and five parts of metallic iron in a divided state (such
as iron borings or turnings), or seven parts of the oxide of iron. I then expose
this mixture to a red heat, when the sulphate becomes decomposed; sulphur
contained therein combining with the iron forms sulphuret of iron, and car-
bonic acid gas is also formed, part of which combining with the soda or potash
which the mixture contained forms carbonate of soda or carbonate of potash
(as the case may be), and the remainder of such carbonic acid gas is evolved.
This operation may be effected either in an open furnace or in a closed retort,
but I prefer to employ a closed retort, because I can then collect the carbonic
gas which is evolved, and which is applicable for the several purposes for
which I use carbonic acid gas in the several processes or operations herein
inentioned. By this operation I obtain a mixture containing sulphuret of iron
and carbonate of soda or carbonate of potash (as the case may be), and I then
separate the sulphuret by lixiviating the mixture with water, and obtain
sulphuret of iron mixdd with water; I put this mixture of sulphuret of iron
and water into a suitable vessel capable of being closed, and furnished with a
tube fitted for introducing acid into the vessel, and with a pipe for introducing
steam, and with a gas tube for conducting off gas. I then close the vessel
and introduce muriatic acid or sulphuric acid into it by means of the tube
fitted for that purpose.
The sulphuret of iron becomes decomposed, and
acid

page_text: sulphur in combination with hydrogen gas is liberated by the action of the
acid upon the sulphuret, and passes off by the gas tube. I continue to intro-
duce into the vessel such acid as I employ, until the decomposition of the
sulphuret is complete; and I inject steam into the vessel in order to promote
or facilitate the disengagement of gas from the mixture and the action of acid
upon the sulphuret.
I will now describe certain processes by which I extract sulphur (which I
obtain in combination with hydrogen gas) from sulphate of lime, for the pur-
pose of applying such sulphur in preparing or manufacturing sulphuric acid.
I mix together sulphate of lime and coke, both in powder, in the proportion by
weight of six parts of sulphate of lime and one part of coke, and I expose
this mixture to a red heat; I thus obtain sulphuret of calcium and carbonic
acid gas.
This operation may be effected either in an open furnace or in a
closed retort, but I prefer to employ a closed retort, because I can then collect
the carbonic acid gas which is evolved, and which is applicable for the several
purposes for which I use carbonic acid gas in the several processes or opera-
tions herein mentioned; having thus obtained sulphuret of calcium, I decom-
pose it by the action of muriatic acid or of carbonic acid and water, and thus
obtain sulphur in combination with hydrogen gas. When I employ muriatic
acid to effect this decomposition I mix the sulphuret with water, and I put the
mixture thus obtained into a suitable vessel capable of being closed, and
furnished with a tube for introducing muriatic acid into the vessel, and with a
pipe for introducing steam, and with an agitator for assisting the mixing of
the acid with the mixture of sulphuret and water, and also with a gas tube for
conducting off gas. I then close the vessel and introduce muriatic acid into it
by means of the tube provided for that purpose, and at the same time I agitate
the mixture contained in the vessel. The sulphuret is decomposed by the
action of the muriatic acid, and sulphur in combination with hydrogen gas is
liberated. This gas passes off by the gas tube, and I collect and apply it as
herein-after mentioned. I continue to introduce muriatic acid into the vessel
until the decomposition of the sulphuret is complete, and I also inject steam
into the vessel in order to promote or facilitate the disengagement of gas from
the mixture contained therein, and the action of the acid upon the sulphuret.
When I employ carbonic acid to decompose this sulphuret of calcium, I mix
the sulphuret with a suitable proportion of water to produce a damp powdery
mixture, and I cause this mixture to absorb carbonic acid gas, by which the
sulphuret is decomposed, and sulphur in combination with hydrogen gas is
obtained.
When I employ carbonic acid gas with any of the. sulphurets which I have

page_text: mentioned, I use for this purpose an apparatus consisting of a series of vessels
containing perforated trays, constructed like the vessels commonly used for
purifying coal gas by the process called "dry lime purification," and I spread
the sulphuret in layers upon these trays. I then cause carbonic acid gas to
filter through the layers of sulphuret in such manner as that the gas traverses
through a number of these layers in succession; and I arrange the vessels
containing the sulphuret in such manner as that the carbonic acid gas is first
brought into contact with sulphuret which has been previously in part acted
upon and almost entirely decomposed by carbonic acid gas, and then passes
successively through other layers of sulphuret which have been previously
acted upon by such gas in a less degree, and it is ultimately brought into
contact with sulphuret which is nearly or entirely fresh. I thus effect the
absorption of carbonic acid gas by the sulphuret, and obtain sulphur in com-
bination with hydrogen gas.
In the operation which I have thus last described, it is essential that the
sulphuret should be moistened with water, or that steam should be introduced
into the vessels with the carbonic acid gas. When I have obtained sulphur
in combination with hydrogen gas, forming sulphuretted hydrogen gas from
sulphate of soda, or sulphate of potash, or sulphate of lime, I collect this
gas in a gasometer, or in any other convenient apparatus, and if the sul-
phuretted hydrogen gas so obtained is sufficiently free from mixture with other
gas to be suitable to be applied at once in preparing or manufacturing sulphuric
acid, I transfer it through pipes into an oven or small chamber, similar to
those employed for burning sulphur in the ordinary method of manufacturing
sulphuric acid, and communicating with a larger chamber; and as it passes
from the pipes I cause it to undergo combustion and maintain a current of
atmospherical air, by the means usually employed for that purpose during the
combustion of sulphur in the manufacture of sulphuric acid by the ordinary
method. I thus produce sulphurous acid and water, and I cause these to pass
into the larger chamber together with atmospherical air; and by the use of a
suitable quantity of nitrous vapours in such larger chamber I convert the
sulphurous acid into sulphuric acid. When I use the carbonic acid gas which
is obtained in those operations which I have described as furnishing this gas,
to effect the actions which I have described upon the several sulphurets herein-
before mentioned, I procure sulphuretted hydrogen gas sufficiently free from
other gas to be used at once in preparing or manufacturing sulphuric acid, in
the manner herein-before mentioned. For effecting these actions, I also use
carbonic acid gas which is mixed with other gas (as is the case with the
carbonic acid gas obtained by the combustion of carbon with atmospherical

page_text: air), and the sulphuretted hydrogen gas thus obtained is not sufficiently free
from other gas to be applied in preparing or manufacturing sulphuric acid in
the manner which I have already described for this purpose. When I have
obtained such sulphuretted hydrogen gas mixed with other gas, I prefer to
cause one-third part of the sulphur contained therein to undergo combustion
with atmospherical air, and to mix the gas produced by this combustion with
the gas containing the remainder of the sulphur, and to introduce these
mixed gases into a suitable chamber or vessel, together with steam or water.
These gases will then react upon each other, and sulphur will be obtained
mixed with water. I separate this sulphur from the water, and it is then
suitable to be used in preparing or manufacturing sulphuric acid in the same
manner as the ordinary sulphur of commerce is applied to this purpose.
In effecting the combustion of sulphur contained in sulphuretted hydrogen
gas mixed with other gas, I prefer to assist this combustion in the first
instance by means of heat, and to effect it in an oven into which I introduce
the pipes conveying gas.
This oven is similar to the ovens used for burning
sulphur in the ordinary method of manufacturing sulphuric acid, and has a
chimney for the purpose of obtaining a draft or current of atmospherical air,
which chimney is fitted with dampers, so as to admit of its being connected
with the chamber or vessel before referred to, or with the atmosphere. Within
the oven I build an arch at a distance of about one foot from the floor, and I
leave apertures in this arch, for the passage of gas produced by combustion.
In the first instance, I make this arch hot by burning coal or coke on the
floor of the oven, the chimney being then open to the atmosphere; and after
the arch has been sufficiently heated I close the passage of the chimney to the
atmosphere, and open the passage to the chamber or vessel. I then allow
sulphuretted hydrogen gas to pass from the pipes, and the sulphur undergoes
combustion with the current of atmospherical air passing through the oven,
and the gas produced passes into the chamber or vessel in which the mixed
gases are to react on each other, as herein-before described. The combustion
of sulphur contained in the gas will keep the arch at a sufficient heat, so
long as such combustion is continued, but if the arch be allowed to become
cool, coal or coke must be used again for heating it, as I have already
described.
of
Now, I hereby declare that I do not confine myself to the use or application
any particular apparatus for effecting any of the processes or operations
herein before mentioned, nor to the particular modes which I have herein
described for using or applying the sulphur obtained by the several actions
herein before mentioned, in preparing or. manufacturing sulphuric acid; nor

page_text: to the use of the particular proportions of materials herein-before described;
nor to the use of coke for effecting the decomposition of the sulphates herein-
before mentioned, as other kinds of carbon may be used for this purpose.
And I further declare that I do not claim any privilege in respect of the appa-
ratus herein described, nor to the preparation of the several sulphurets herein
described, nor to the use of any of the actions herein described, except so far
as the same may be used for extracting sulphur from the substances herein
specified, for the purpose of applying this sulphur to the manufacture of
sulphuric acid.
But I claim as my Invention the use or application in preparing or manu-
facturing sulphuric acid of sulphur contained in sulphate of soda, or sulphate
of potash, and extracted by the action of hydrogen upon such sulphates, or
extracted by the joint action of carbonic acid and water upon the sulphuret
of sodium or sulphuret of potassium, obtained by the decomposition of such
sulphates respectively, or extracted by the action of muriatic acid or sulphuric
acid upon sulphuret of iron, obtained by the decomposition of such sulphates
respectively. And also the use or application in preparing or manufacturing
sulphuric acid of sulphur contained in sulphate of lime, and extracted by the
action of muriatic acid or of carbonic acid and water upon the sulphuret of
calcium obtained by the decomposition of this sulphate.
In witness whereof, I, the said John Fowler, have hereunto set and
affixed my hand and seal, this Fifteenth day of April, One thousand
eight hunded and thirty-nine