IMPROVEMENTS IN THE MANUFACTURE OF COAL GAS USED FOR ILLUMINATING PURPOSES
Year: 1856

page_text: PROVISIONAL SPECIFICATION left by William Gossage at the Office of
the Commissioners of Patents, with his Petition, on the. 17th October
1856.
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 COAL GAS USED FOR ILLUMINATING PURPOSES," to be as follows:-
-
is
In the manufacture of gas by distillation from coal, the crude coal gas
produced contains (in addition to the gaseous compounds of carbon and
hydrogen constituting coal gas proper for. illumination) hydrosulphuret of
ammonia and sulphuretted hydrogen, which sulphureous compounds
desirable to separate from the coal gas. This separation constitutes the pro-
cess called purification, and the more effectually such separation is accom-
plished, the more suitable is the, gas produced for, purposes of illumination.
The separation of hydrosulphuret of ammonia from coal gas is usually effected
to some extent by simple cooling, and a product is thereby obtained called
gas ammoniacal liquor," which contains hydrosulphuret of ammonia in.
solution by water, but the coal gas still retains after this process much
hydrosulphuret of ammonia in the state of vapour, also sulphuretted, hydrogen.
The employment of hydrate of lime, either in the state of powder, or mixed
with water so as to form "cream of lime," is usually adopted, to separate the
last portions of hydrosulphuret of ammonia from coal gas, and the whole or
the greater part of the sulphuretted hydrogen is also thereby separated
therefrom.

page_text: In effecting my Invention, I also separate hydrosulphuret of ammonia from
crude coal gas by cooling, and thereby obtain liquor containing bydrosulphuret
of ammonia; and I complete the separation of the hydrosulphuret of am-
monia, and also effect the decomposition of sulphuretted hydrogen present in
the crude coal gas, by the use of sulphurous acid, either in the gaseous state,
or dissolved in water. By the action of sulphurous acid on hydrosulphuret of
ammonia contained in crude coal gas sulphite of ammonia is produced, and an
additional proportion of sulphuretted. hydrogen is added to the crude coal gas.
The further introduction of sulphurous acid into the crude coal gas occasions
sulphuretted hydrogen present therein to become decomposed, thereby
producing sulphur and water, which I separate from the coal gas, either by
deposition or filtration; and I thus obtain sulphur as a valuable product, also
sulphite of ammonia, by the same operation by which I deprive coal gas of
injurious sulphur compounds.
I can obtain sulphurous acid for such purpose by the combustion of sulphur
with atmospherical air or oxygen gas, or by other well-known means; but-I
prefer to obtain such acid by the decomposition of sulphite of ammonia, or
some other alkaline sulphite, by means of sulphuric acid or other suitable
acid.
I also obtain sulphite of ammonia by decomposing hydrosulphuret of
ammonia contained in gas ammoniacal liquor by sulphurous acid gas in excess,
and thereby causing sulphurous acid gas to become mingled with sulphuretted
hydrogen gas resulting from such decomposition, and producing sulphur and
water, by the mutual reaction of sulphurous acid gas and sulphuretted
hydrogen gas.
In effecting my Invention, I obtain considerable quantities of sulphite of
'ammonia or other salt of ammonia in solution by water, and I concentrate
such solution by passing the same through a tower or cylindrical vessel con-
taining pieces of coke or of other suitable material, through which a current
of heated air is also passed, and I connect such apparatus with a chimney, and
thus draw off the vapours passing therefrom.