IMPROVEMENTS IN THE PURIFICATION OF COAL GAS
Year: 1866

page_text: LETTERS PATENT to John Leigh, of the City of Manchester, in the County
of Lancaster, for the Invention of "IMPROVEMENTS IN THE PURIFICATION
OF COAL GAS."
Sealed the 19th October 1866, and dated the 20th April 1866.
PROVISIONAL SPECIFICATION left by the said John Leigh at the Office-
of the Commissioners of Patents,, with his Petition, on. the 20th April
1866.
I, JOHN LEIGH, of the City of Manchester, in the County of Lancaster, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN THE.
PURIFICATION OF COAL GAB," to be as follows:-
1. I use gas or ammonia water in its ordinary crude state, that is to say,
as it is ordinarily produced in the manufacture of coal gas, and concentrate it
by distillation, and treat the gas therewith. The word "treat" in this case
means that the gas is to be passed through the gas water concentrated as
described and allowed to fall in showers in ordinary gas washers; or the con-
centrated gas water may be absorbed by sawdust,. coke, pumicestone, or dry
porous material, and placed in ordinary lime or copper as purifiers, and the
gas passed through the coke, sawdust, pumicestone, or dry porous material so
saturated.
2. Or I treat the crude ordinary gas liquor or ammonia water with
quicklime, thereby depriving the ammonia water of its carbonic acid, and
concentrate it by distillation. The word "treat" here means simply that the

page_text: gas water is to be mixed and agitated with lime until the carbonic acid is
removed from the gas water.
3. Or I treat the crude or ordinary gas liquor or ammonia water with spent
or refuse lime of gasworks which has been previously used for purification of
gas, thereby depriving the ammonia water of a portion of its carbonic acid
and imparting to it a portion of sulphur, and concentrate the liquor by dis-
tillation. The word "treat" here means that the gas water is to be mixed
and agitated with the spent or refuse lime of gasworks till the gas water is
deprived of a portion or all of its carbonic acid.
4. The distilled and concentrated gas water prepared by the first method
may be treated by quicklime, or by the spent or refuse lime of gasworks
after the distillation and concentration. The word "treat" means mixed and
agitated as before described.
5. To the distilled and concentrated gas water prepared by the second
method and third method I prefer to add a portion of sulphur which will
dissolve therein, and by which the energy of its action on bisulphide of carbon
is increased.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said John Leigh in the Great Seal Patent Office on the 19th
October 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOHN
LEIGH, of the City of Manchester, in the County of Lancaster, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twentieth day of April, in the year of our Lord
One thousand eight hundred and sixty-six, in the twenty-ninth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me, the
said John Leigh, Her special license that I, the said John Leigh, my
executors, administrators, and assigns, or such others as I, the said John
Leigh, 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 PURIFICATION OF COAL GAS," upon the condition (amongst others) that I,
the said John Leigh, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals, should

page_text: 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 John Leigh, do hereby declare the
nature of my said Invention, and in what manner the same is to be per-
formed, to be particularly described and ascertained in and by the following
statement (that is to say) :-
1. I use gas liquor or ammonia water in its ordinary crude state, that is to
say, as it is ordinarily produced in the manufacture of coal gas, and con-
centrate it by distillation and treat the gas therewith. The word treat in this
case means that the gas liquor so concentrated is to be injected into the
ordinary scrubbers, washers, or other similar vessels, so as to fall in showers
into the current of gas, which as it is manufactured is passing through the
scrubbers; or the concentrated gas water may be absorbed by sawdust, coke,
pumicestone, or other dry porous material, and placed in ordinary lime or
copperas purifiers and the gas passed through the coke, sawdust, pumice or
dry porous material so saturated.
2. Or I treat the crude ordinary gas liquor or ammonia water with quick-
lime, thereby depriving the ammonia water of its carbonic acid, and concentrate
it by distillation. The word treat here means simply that the gas water is
to be mixed and agitated with lime until the carbonic acid is removed from
the gas water.
3. Or I treat the crude or ordinary gas liquor or ammonia water with the
spent or refuse lime of gasworks, which has been previously used for the
purification of gas from sulphuretted hydrogen, thereby depriving the ammonia
water of a portion of its carbonic acid, and imparting to it a portion of sulphur,
and concentrate the liquor by distillation. The word treat here means that
the gas water is to be mixed and agitated with the spent or refuse lime of
gasworks till the gas water is deprived of a portion or all of its carbonic acid.
4. The distilled and concentrated gas water prepared by the first method
may be treated by quickline, or by the spent or refuse lime of gasworks,
after the distillation and concentration; treat here means mixed and agitated
as before-described.
5. To the distilled and concentrated gas water prepared by the second
method and third method I prefer to add a portion of sulphur, which will
dissolve therein, and by which the energy of its action on bisulphide of carbon
is increased.
Or I distil the crude gas water in a suitable boiler, and pass the vapour or

page_text: steam evolved in the distillation into a vessel containing a quantity of spent lime,
that is, lime which has been used for the removal of sulphuretted hydrogen
from coal gas, such lime being contained in a vessel which is heated or otherwise,
but by preference heated, as the decomposition which is sought to be effected
between the spent lime or refuse lime and the distilled ammonia water or
gas water more readily takes place and the product is more easily removed at
an elevated temperature than at ordinary temperatures. The product is then
carried forward to a suitable condensing vessel or apparatus, and may be
injected into the ordinary washers used in the purification of coal gas by the
use of pumps, as now ordinarily practised in the use of common undistilled
and unconcentrated gas water.
Or I distil the crude gas water through a quantity of the refuse lime, or
spent lime of gasworks, that is, lime that has already been used for the
removal of sulphuretted hydrogen from coal gas, such lime being arranged in
layers, or in such mode as that the steam or vapour of the ammonia water or
gas water may pass through the spent or refuse lime, and may be more or
less decomposed thereby, that is to say, that the carbonate of ammonia in the
vapour or steam of the distilling gas water may impart a portion of its carbonic
acid to the lime, and may receive from the latter a portion of sulphur.
The sulphuretted vapour or steam of the gas water is then carried forward
in a suitable manner to the washers or condensers ordinarily used in the
washing or purification of coal gas, and therein mixed with the gas to be
purified; the mixed gas and vapour to be afterwards passed through a
suitable condenser, and the liquid regained.
Having now described the nature and particulars of my said Invention, and
the manner in which the same is to be performed, I desire it to be understood
that I claim,-
The use of distilled and concentrated gas water or ammonia water, whether
such ammonia water or gas water be,
Firstly, distilled and concentrated in its ordinary crude state, that is, as it
is ordinarily produced in the manufacture of coal gas; or,
Secondly, previously cauticised by the addition of lime to the gas water, so
as to remove the carbonic acid therefrom, and then concentrated by dis-
tillation; or,
Thirdly, by treating the crude ordinary gas liquor or gas water or ammonia
water with the spent lime or refuse lime of gasworks, that is, lime which has
been previously used for the purification of gas, so as thereby to deprive the
ammonia water of a portion of its carbonic acid and impart to it a portion of
sulphur.

page_text: Fourthly, the distilled and concentrated gas water as prepared by the first
method and treated by quicklime, or by the spent or refuse lime of gasworks,
that is, after the distillation and concentration.
And, fifthly, the use of distilled and concentrated gas water, however pre-
pared, and whether causticised or sulphuretted before or after the distillation.
In witness whereof, I, the said John Leigh, have hereunto set my hand
and seal, this Eighteenth day of October, in the year of our Lord
One thousand eight hundred and sixty-six.
Signed, sealed, and delivered by the
within-named John Leigh, in the
presence of,
E. J. HUGHES,
Patent Agent,
Manchester.
JOHN LEIGH. (L.S.)