AN IMPROVEMENT FOR PURIFYING COAL GAS BY MEANS NOT HITHERTO USED FOR THAT PURPOSE
Year: 1827

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
F. LEDSAM, of Birmingham, in the County of Warwick, Merchant, send
greeting.
WHEREAS His present most Excellent Majesty King George the Fourth,
by His Letters Patent under the Great Seal of Great Britain, bearing date
at Westminster, the Second day of March, in the eighth year of His reign,
did, for Himself, His heirs & successors, give & grant unto me, the said
Joseph F. Ledsam, His especial licence that I, the said Joseph F. Ledsam,
my exors, admors, and assigns, or such others as I, the said Joseph F.
Ledsam, my exors, adñiors, or assigns, should at any time agree with, and
no others, from time to time and at all times during the term of years
therein expressed, should and lawfully might make, use, exercise, and vend,
within England, Wales, and the Town of Berwick-upon-Tweed, and also
in all His said Majesty's Colonies and Plantations abroad, the Invention for
"AN IMPROVEMENT FOR PURIFYING COAL GAS BY MEANS NOT HITHERTO USED FOR
THAT PURPOSE;" in which said Letters Patent is contained a proviso obliging
me, the said Joseph F. Ledsam, by an instrument in writing under my hand
and seal, particularly to describe and ascertain the nature of the said Inven-
tion, and in what manner the same is to be performed, and to cause the
same to be inrolled in His said Majesty's High Court of Chancery within
six callendar months next and immediately after the date of the said recited
Letters Patent, as in and by the same, reference being thereunto had, will
more fully and at large appear.

page_text: NOW KNOW YE, that in compliance with the said proviso, I, the said
Joseph F. Ledsam, do declare that the nature of my said Invention or improve-
ment in purifying coal gas consists in the application of well-known materials
to effect that object, and that the said improvement may be divided into two
parts; first, the purifying or rendering the coal gas suitable for the purposes of
illumination after it passes out of the retorts; and, secondly, the purifying or
destroying the fetid odour or noxious effluvia of the gas.
gas
To effect the former of these objects I use ammonia. The ammoniacal liquor
obtained from the distillation of coal I employ in a peculiar way. I convert a
quantity of the ammoniacal liquor into muriate of ammonia by saturating it with
muriatic acid; it is then evaporated sufficiently and chrystalized. One hundred
pounds of the muriate thus obtained are dissolved in water contained in a large
vessel called the purifyer, and about fifty pounds of lime are added to it. The
coal gas, after having passed through a vessel of water, is then suffered to pass
through the liquor in the purifyer, the sulpheretted hydrogen which it contains
united with the ammonia becomes soluble in water, and remains principally in
the purifyer; some portion of it, however, which may go over with the coal g
is arrested by another vessel containing water. When the muriate of
ammonia in the purifyer is spent, the liquor is drawn off and a fresh supply of
the materials put in. To the liquor that has been used in the purifier, a
sufficient quantity of, muriatic acid is added, and by subsequent evaporation
and chrystalization the muriate of ammonia is recovered together with muriate
of lime. The latter is used instead of muriatic acid for converting the
ammoniacal liquor into muriate of ammonia. I have sometimes employed
the sulphate of ammonia instead of the muriate, which I obtain either by
saturating the ammoniacal liquor with sulphuric acid or by the use of gypsum;
and when I use the sulphate of ammonia I add to it magnesian lime instead
of common lime, by which means I obtain from the liquor after it is taken
out of the purifyer, besides the ammonia, a quantity of sulphate of magnesia.
To effect the second object of my improvement, viz., destroying the fetid
odour of the gas, I use the chloruret of oxide of sodium or the chloruret of
oxide of calcium. I prefer the chloruret of lime, as being the most economical
for this purpose. I pass the gas through one or more vessels containing a
solution of the chloruret of lime. The proportion ought to be about one part
of the chloruret to about thirty or forty parts of water, and about the same
proportion where the concentrated chloruret of soda is used, though the
proportions of each may be varied according to circumstances & the heat of
the weather. The vessel or vessels ought to be air-tight, and the gas be
passed from one to another until it is completely purified from any disagree-

page_text: able smell. I sometimes also use the chloruret in a dry state, spreading it in
a thin surface in a vessel or vessels and causing the gas to pass over it, but I
prefer it in solution, as less troublesome and more effectual in its operation.
The size and shape of the vessels is not material, though I have preferred
them a few inches deep, and of a size proportioned to the quantity of gas
requiring to be purified. A small vessel, about four inches deep and eighteen
inches square, would suffice for a single burner or two in a close room.
Larger vessels would be requisite for extensive gasworks. The material will
require to be stirred up occasionally and sometimes renewed, though its
purifying qualities will be retained for a long period. I have found by this
method that the coal gas is not only rendered free from offensive smell but the
air of the apartments and other places where the gas is consumed is rendered
both sweet and wholsome.
The Patentee claims as original, the application and use of ammonia for
purifying the coal gas, and rendering it suitable for purposes of illumination,
and the application and use of the chlorurets of sodium and calcium for
purifying the coal gas from its fetid odour either in a dry state or in solution.
In witness whereof, I, the said Joseph F. Ledsam, have hereunto set
my hand and seal, this Twenty-seventh day of August, in the year of
our Lord One thousand eight hundred and twenty-seven.