IMPROVEMENTS IN PURIFYING GAS
Year: 1858

page_text: LETTERS PATENT to Thomas Bell, of Plaistow, in the County of Essex,
. for the Invention of "IMPROVEMENTS IN PURIFYING GAS."
Sealed the 1st April-1859, and dated the 30th December 1858.
PROVISIONAL SPECIFICATION left by the said Thomas Bell at the
Office of the Commissioners of Patents, with his Petition, on the
30th December 1858.
I, THOMAS BELL, of Plaistow, in the County of Essex, do hereby declare
the nature of the Invention for "IMPROVEMENTS IN PURIFYING GAS," to be as
follows:-
This Invention has for its object improvements in purifying gas. For this
purpose I employ a substance which at the present time has but a very small
or no commercial value, viz., the residuum resulting from the working of
Longmaid's process for the manufacture of sulphate of soda
; this process
consists in roasting common salt with iron pyrites, which results in the con-
version of the soda into sulphate, and of the iron into red oxide. Afterwards
the soda salt is dissolved out, leaving a residuum which is the substance I
employ, and I find it to have like purifying properties to oxide of iron of the
form and purity at present used for purifying gas. For the same purpose I
also employ the oxide of iron refuse obtained by burning iron pyrites in the
manufacture of sulphuric acid, and this substance I in some cases prepare by.
grinding and washing, so as to obtain an impalpable powder, which when dry
is ready for use. By bringing hæmatite iron ores to a red heat, and-after-

page_text: wards grinding and washing them, I reduce them to a form in which they are
suitable for use in the purification of gas. A substance suitable for the
purification of gas may also be prepared by roasting copperas, either alone or
with lime, magnesia, or alkali, together with coal or carbonaceous matter.
Either of the above ferruginous materials after it has been used for the
purification of gas, and has become charged with sulphur, is, according to my
Invention, rendered fit to be again used for purifying gas by driving off the
sulphur by heat, and this is either done by heating the substance in retorts
so as to distil off the sulphur of by burning it off.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Thomas Bell in the Great Seal Patent Office on the
30th June 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, THOMAS
BELL, of Plaistow, in the County of Essex, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Thirtieth day of December, in the year of our
Lord One thousand eight hundred and fifty-eight, in the twenty-second
year of Her reign, did;. for Herself, Her heirs and successors, give and
grant unto me, the said Thomas Bell, Her special licence that I, the said
Thomas Bell, my executors, administrators, and assigns, or such others
as I, the said Thomas 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
ચંદ્ર IMPROVEMENTS IN PURIFYING GAS," upon the condition (amongst others) that
I, the said Thomas Bell, my executors or administrators, by an instrument
in writing under my, or their, or one of their hands and seals, should par-
ticularly 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 Thomas Bell, do hereby declare the
nature of the 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 thereof, that is to say:

page_text: This Invention has for its object improvements in purifying gas. For this
purpose I employ a substance which at the present time has but a very small
or no commercial value, viz., the residuum resulting from the working of
Longmaid's process for the manufacture of sulphate of soda. This process.
consists in roasting common salt with iron pyrites, which results in the con-
version of the soda into sulphate, and of the iron into red oxide. Afterwards
the soda salt is dissolved out, leaving a residuum which is the substance I
employ, and I find it to have like purifying properties to oxide of iron of the
form and purity at present used for purifying gas. The following is the
manner in which I prefer to operate:-The above mentioned residuum is
taken in the state in which it can be obtained from works where Longmaid's
process is employed, and if necessary it is wetted just sufficiently to cause it
to bind when pressed together. In this state it is placed on the shelves of
the purifiers, which are of a similar construction to those which are commonly
used when dry lime is employed for purifying gas; the gas is passed through
the purifiers as heretofore, and is tested from time to time to ascertain if the
process is proceeding satisfactorily. When the gas comes over in an impure
state, the material in one of the series of purifiers is renewed, and the purifiers
employed are in this manner recharged in rotation as it becomes necessary.
The material discharged is spread out on the ground, and after three or four
days it becomes fit to be again used. For the same purpose I also employ
the oxide of iron refuse obtained by burning iron pyrites in the manufacture
of sulphuric acid, and this substance I in some cases prepare by grinding and
washing, so as to obtain an impalpable powder, which when dry is ready for
use. The best method of preparing this material is by crushing it under edge
runners, or with other convenient grinding apparatus; it is then washed by
throwing it into water and stirring it well up, when it has stood a few seconds
the water is run off together with the finer particles of the burnt pyrites, but
leaving the coarser particles, which settle to the bottom of the vessel. The
liquid run off is allowed to stand until the fine powder deposits; this is then
removed, and when the water is sufficiently separated it is ready for use, and
is employed in the manner already described. Burnt pyrites which is simply
ground and passed through a sieve having about twenty holes to the inch, will
purify gas efficiently, although not so well as when it is prepared by washing
as before described. By bringing hoematite iron ores to a red heat, and after-
wards grinding and washing them, I reduce them to a form in which they
are suitable for use in the purification of gas. Hoematite ore for this purpose
should be rich in iron to prepare it for use, I place it in a reverberatory
furnace and heat it to a red heat, just visible in ordinary daylight; it is then

page_text: ground and washed in the manner already described. This material is applied
in the same way as the Longmaid's refuse, but will require changing more
frequently. A substance suitable for the purification of gas may also be
prepared by roasting copperas either alone or with lime or magnesia together
with coal or carbonaceous matter. The following is, the mixture I prefer to
employ-To twenty parts of copperas, I add two parts of lime and one part
of coal all in a fine powder, and heat the mixture in a reverberatory furnace,
to a dull red heat. Afterwards it is ready to be placed in the purifiers as
before, and it is worked in a similar manner to the other materials before
mentioned. Either of the above ferruginous materials after it has been used
for the purification of gas and has become charged with sulphur, and which
usually happens when it has been passed about thirty times through the
purifiers, is, according to my Invention, rendered fit to be again used for
purifying gas by driving off the sulphur by heat, and this is either done by
heating the substance in retorts so as to distill off the sulphur or by burning it
off. For distilling off the sulphur, I place the material in an earthenware or
iron retort, which is then raised to a dull red heat, and the sulphur vapours
are conducted by a pipe into water, by which the sulphur is condensed...
In witness whereof, I, the said Thomas Bell, have hereunto set my
hand and seal, this Thirtieth day of June, in the year of our Lord
-One thousand eight hundred and fifty-nine.
THOMAS DELL