AN IMPROVEMENT APPLICABLE TO GAS PURIFYING
Year: 1858

page_text: LETTERS PATENT to Frederick John Evans, of the Chartered Gas Works,
Horseferry Road, Westminster, Engineer, for the Invention of "AN
IMPROVEMENT APPLICABLE TO GAS PURIFYING."
Sealed the 16th November 1858, and dated the 27th August 1858.
PROVISIONAL SPECIFICATION left by the said Frederick John Evans at
the Office of the Commissioners of Patents, with his Petition, on the
27th August 1858.
I, FREDERICK JOHN EVANS, of the Chartered Gas Works, Horseferry Road,
Westminster, Engineer, do hereby declare the nature of the said Invention.
for "AN IMPROVEMENT APPLICABLE TO GAS PURIFYING," to be as follows:-
My Invention relates to the production of oxide of iron, and employment of
the same in the purification of gas. The oxides of iron heretofore employed
for the purification of gas have usually been obtained either from natural
sources, in the form of ochres or natural oxides, or from the decomposition of
the sulphates or other salts of iron. All ochres or natural or native oxides are
mixed with earthy matters which have no affinity for the impurities contained
in gas, and are consequently inert and useless. The oxides obtained by the
decomposition of the sulphates or other salts of iron are purer, but are much
more costly to obtain.
The object of my Invention is to obtain a material which will be energetic
in its action, easy of production, and inexpensive. To this end I take turnings,
borings, and filings of iron or scrap iron, and expose them to gases or liquids
(whether at ordinary or elevated temperatures), that will insure their rapid

page_text: oxidation. When the surfaces are completely coated with oxide, the turnings,
borings, filings, or thin pieces of iron may be placed in a dry gas purifier, and
the impure gas allowed to percolate through the mass, when certain of the
impurities contained in the gas will be arrested by and combine with the oxide
of iron. On the oxidized iron turnings, &c. becoming saturated with the
impurities they are removed from the purifier, and exposed a second time to
the action of the atmosphere. A portion of the sulphur that has been extracted
from the gas and taken by the iron into chemical combination will then
become separated therefrom, and the oxide of iron will return to its original
state and be fit for purifying gas, as before. The mode which I prefer for
converting iron filings, turnings, scrap iron, &c. into a purifying material is, to
mix the same with the saturated purifying material immediately it is removed
from the purifier, when the chemical action of revivifying set up by exposure
of the material to the air will assist in effecting the rapid oxidation of the
iron, which may then be used with the revivified oxide for the purification
of gas.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Frederick John Evans in the Great Seal Patent Office on
the 26th February 1859.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FREDERICK
JOHN EVANS, of the Chartered Gas Works, Horseferry Road, Westminster,
Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-seventh day of August, 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 Frederick John Evans, Her special license that I, the said Frederick
John Evans, my executors, administrators, and assigns, or such others as
I, the said Frederick John Evans, 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
"AN IMPROVEMENT APPLICABLE TO GAS PURIFYING," upon the condition (amongst
others) that I, the said Frederick John Evans, by an instrument in writing
under my hand and seal, should particularly describe and ascertain the nature

page_text: 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 Frederick John Evans, do hereby
declare the nature of my said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement (that is to say) :-
In the purifying of illuminating or carburetted hydrogen gas, it is now the
general practice to employ some preparation or natural compound of oxide of
iron for the removal of the impurity known as sulphuretted hydrogen. These
oxides of iron have usually been obtained either from natural sources in the
form of ochres or natural oxides, or from the decomposition of the sulphates or
other salts of iron. All ochres or natural or native oxides, however, are mixed
with earthy matters, which, having no affinity for the impurities contained in
gas, are consequently inert and useless ingredients. The oxides obtained by
the decomposition of the sulphates or other salts of iron are purer, but are
much more costly to obtain, and although they admit of being frequently
revivified, yet their use forms a heavy annual item of expense in the gas
works.
The object of my Invention is to obtain a material which will be energetic
in its action, easy of production, and inexpensive. To this end I take turnings,
borings, and filings of iron or scrap, or small pieces of iron in the form of shot,
for example, and expose the same to gases or liquids, whether at ordinary or
clevated temperatures, that will ensure their rapid oxidation. When the
surfaces of the turnings, borings, filings, or thin pieces of iron are completely
coated with oxide or rust, the metal thus oxidized is ready for use in the dry
gas purifiers, where it is to be employed in the manner usually practised when
purifying gas with the oxides above referred to, that is to say, a set or series of
purifiers is employed, the same being suitably connected together by pipes,
and the gas is led through the several purifiers in succession, entering first that
which contains the purifying material most impregnated with sulphur, and passing
last through that whose oxide is the least impregnated with sulphur. The
impure gas being thus allowed to percolate through the mass of oxide of iron
contained in the several purifiers certain of the impurities contained in the gas
will be arrested and caused to combine with the oxide of iron. On tho
oxidized iron turnings, &c. in the first purifier becoming saturated with the
impurities deposited by the gas, which is shewn by the test constantly applied
to the gas by the attendant, that purifier is thrown out of action and the gas
"

page_text: is led to the second, which becomes in its turn the first purifier, and a freshly
charged purifier is brought into the series. The saturated oxide is then
removed from the purifier, and exposed a second time to the action of the
atmosphere. A portion of the sulphur that has been extracted from the gas
and taken by the iron into chemical combination will then become separated
therefrom, and the oxide of iron will return to its original state and be fit for
purifying gas as before. The mode which I prefer for converting iron filings,
turnings, and borings, and scrap iron into a purifying material is to mix the
same with the saturated purifying material immediately it is removed from the
purifier, when the chemical action of revivifying set up by exposure of the
material to the air will assist in effecting the rapid oxidation of the iron, which
may then be used with the revivified oxide for the purification of gas.
To prepare the oxide in the first instance, supposing no saturated material
to be at hand, I spread out the filings, turnings, or scrap iron on the ground,
and expose the heat to the atmosphere, either with the addition of water or not,
according to the state of the atmosphere. When so exposed for about twenty-
four hours, more or less, the surfaces of the particles or pieces of the metallic
iron will be found to be coated sufficiently with rust or oxide to serw as an
cfficient purifier of gas from sulphuretted hydrogen. When, by repeated
revivification and use, the purifying material is found to have increased in bulk
by the mechanical admixture of sulphur therewith derived from the impure
gas, so as materially to impair its energetic action, I submit the material to a
furnace heat, as heretofore practised, in order to burn or drive off the sulphur,
after which the material may be again used as an efficient purifier.
Having now set forth the nature of my Invention of "An Improvement
applicable to Gas Purifying," and explained the manner of carrying the same
into effect, I wish it to be understood that under the above in part recited
Letters Patent I claim, the treatment and use of metallic iron in the manner
and for the purpose above described.
In witness whereof, I, the said Frederick Jolin Evans, have hereunto set
my hand and seal, this Twenty-fifth day of February, in the year
of our Lord One thousand eight hundred and fifty-nine.
F. J. EVANS. (L.S.)