IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID
Year: 1853

page_text: LETTERS PATENT to Isaac Lowthian Bell, of the Washington
Chemical Works, Newcastle-upon-Tyne, for the Invention of
"IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID."
PROVISIONAL SPECIFICATION left by the said Isaac Lowthian
Bell at the Office of the Commissioners of Patents, with his
Petition, on the 9th September 1853.
I, ISAAC LOWTHIAN BELL, of the Washington Chemical Works,
Newcastle-upon-Tyne, do hereby declare the nature of the Invention
for "IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID " to be as
follows:-
In the Specification of a Patent granted to me by Her Majesty, and
enrolled (May 17,) under the title of "Improvements in the Treat-
ment of certain Compounds of Iron and Sulphur," the process is fully
described of depriving the residual product known as soda makers
waste of its sulphur by means of iron produced by reducing oxide of
iron in an iron or other blast furnace, by which means a factitious sul-

page_text: phuret of iron, or, as I designate it, factitious pyrites, is obtained. In
applying this factitious pyrites to the manufacture of sulphuric acid
by burning it in kilns or furnaces some difficulty is experienced in
effecting the oxidation of the iron and the combustion of the sulphur,
so that a much larger amount of sulphur remains in the burnt fac-
titious pyrites than is found in burnt native pyrites, when the natural
sulphuret of iron is employed as a source of sulphur in the manufac-
ture of sulphuric acid.
Now my improvements in the manufacture of sulphuric acid consist
in reducing the factitious pyrites to powder; and I prefer doing this by
exposing it to a humid atmosphere, or by throwing water upon it, as is
practised in the slaking of lime, when the factitious pyrites quickly
crumbles down. In this condition the factitious pyrites on exposure to
heat has its sulphur rapidly burnt off.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Isaac Lowthian Bell in the Great Seal Patent
Office on the 8th March 1854.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
ISAAC LOWTHIAN BELJ, of the Washington Chemical Works, Newcastle-
upon-Tyne, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Ier
Letters Patent, bearing date the Ninth day of September, in the
year of our Lord One thousand eight hundred and fifty-three, in the
seventeenth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said Isaac Lowthian Bell, Her special
licence that I, the said Isaac Lowthian Bell, my executors, admi-
nistrators, and assigns, or such others as I, the said Isaac Lowthian
Bell, 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 SULPHURIC ACID," upon the con-

page_text: dition (amongst others) that I, the said Isaac Lowthian Bell, 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 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 Isaac Lowthian Bell, 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):
That whereas Her Majesty's Royal Letters Patent were granted to
me on the Seventeenth day of November, One thousand eight hundred
and fifty-two, for improvements in the treatment of certain compounds
of iron and sulphur, which Invention consists in fusing together a sub-
stance called "tank residuum," or "soda makers waste," and oxide of
iron in a blast furnace, so as to obtain a compound of sulphur and iron,
which I have called "factitious pyrites." When the furnace used for this
purpose is tapped from time to time this "factitious pyrites runs out
of the bottom in the same way as practised in the smelting of iron.
"
In applying this compound of sulphur and iron or "factitious pyrites"
to the manufacture of sulphuric acid I have experienced some diffi-
culty in sufficiently burning off the sulphur. Now my present Inven-
tion consists in treating this factitious pyrites so as to secure that its
sulphur shall be entirely, or almost entirely, burnt into sulphureous acid
when the same is subjected to combustion; and I proceed as follows:-
When the factitious pyrites runs out of the furnace in which it is made,
as detailed, I suffer it to flow into water, taking care to have the water
in such quantity that its temperature is always below the boiling point.
In practice I find that about one thousand cubic feet of water at
ordinary temperatures is sufficient for the treatment of four tons of
melted factitious pyrites. By this operation the factitious pyrites is ob-
tained in the condition of a fine mud or sline. This I remove from
the tank or vessel into which it has been run, and spread in its pasty
state about one and a half inches thick on a heated floor or drying bed,
such as is used by brickmakers for drying bricks before placing them in

page_text: the kilns. The only precaution in this stage of the operation to be
observed is the temperature of the drying floor, which is best kept
at a little below 212 degrees, otherwise the factitious pyrites is very
apt from its extreme combustibility in its present form to take fire. In
from twelve to twenty-four hours the cake so spread is perfectly dry
and ready for the kilns, in which it has to be placed for the purpose of
burning its sulphur into sulphureous acid. These kilns may be of the
ordinary construction employed by sulphuric acid makers when using
the native pyrites for the production of sulphurcous acid, or they
may be varied. I find the combustion of the factitious pyrites pre-
pared in the manner just described is more satisfactorily conducted
when a kiln about ten feet square and six or eight feet high is em-
ployed, arched over at the top, and very similar in form and size to the
kilns used in the burning of lime intended to be made into bleaching
powder. This kiln is connected with the oil of vitriol chambers by means
of a flue or flues in which are provided proper dampers or valves, so
that the communication with the vitriol chambers can be suspended
at pleasure. In such a kiln I pile twenty-five or thirty tons of the
dry cake of factitious pyrites broken into pieces about six inches
square, and then apply a small quantity of fire, when the mass speedily
commences to burn, its combustion being regulated by a cautious
admission of air, otherwise the heat becomes so intense as to fuse the
factitious pyrites under treatment, which would interfere materially
with the combustion of the sulphur, as well as render the subsequent
withdrawal of the charge an operation of considerable difficulty. In
from fourteen to twenty days combustion ceases, when the communica-
tion between the kiln and the vitriol chambers is cut off, the exhausted
charge removed, and a fresh one introduced. The number of such kilns
will vary with the extent of the manufactory, but they ought always to
be sufficiently numerous when charged in succession to secure a pretty
uniform flow of sulphureous acid into the chambers. The nitrous
vapours are introduced in the usual way practised by makers of sul-
phuric acid.
Although I prefer following the mode of treating the factitious pyrites
in the way just described, yet I do not confine myself to it, because the

page_text: same results, or nearly the same, are obtained when the cooled factitious
pyrites has water thrown over it, or is exposed to a humid atmosphere.
The metallic mass crumbles down, and the powder produced thereby
may be mixed with water to the consistency of a paste, which paste
may be exposed on the drying floor to form the cakes ready for the
kilns, as described of the factitious pyrites when run into water.
Now I claim as my Invention the manufacture of sulphuric acid
from factitious pyrites by making the same into a paste, as described,
drying this paste so as to form thin cakes, and afterwards burning these
cakes in suitable kilns.
In witness whereof, I, the said Isaac Lowthian Bell, have here-
unto set my hand and seal, this Seventh day of March, in
the year of our Lord One thousand eight hundred and fifty-
four
10
5
Witness,
HENRY CHATER,
of Newcastle-Tyne,
Solr.
I. LOWTHIAN BELL. (L.S.)