IMPROVEMENTS IN THE PURIFICATION OF GAS, AND IN OBTAINING A VALUABLE PRODUCT IN THE PROCESS, AND FOR THE PREPARATION OF SOME OF THE MATERIALS TO BE USED IN THE SAID PURIFICATION
Year: 1864

page_text: LETTERS PATENT to Frank Clarke Hills, of Deptford, in the County of
Kent, Manufacturing Chemist, for the Invention of "IMPROVEMENTS IN
THE PURIFICATION OF GAS, AND IN OBTAINING A VALUABLE PRODUCT IN THE
PROCESS, AND FOR THE PREPARATION OF SOME OF THE MATERIALS TO BE
USED IN THE SAID PURIFICATION."
Sealed the 28th June 1864, and dated the 29th April 1864.
'PROVISIONAL SPECIFICATION left by the said Frank Clarke Hills
at the. Office of the Commissioners of Patents, with his Petition, on the
29th April 1864.
ERANK CLARKE HILLS, of Deptford, in the County of Kent, Manu-
Cfacturing Chemist, do hereby declare the nature of the said Invention for
IMPROVEMENTS IN THE PURIFICATION OF GAS, AND IN OBTAINING A VALUABLE
PRODUCT IN THE PROCESS, AND FOR THE PREPARATION OF SOME OF THE MATERIALS
TO BE USED.IN, THE SAID PURIFICATION," to be as follows:-
; My first process is for purifying gas from its ammonia and other impurities
by passing it through a material composed of persulphate of iron or proto-
sulphate of iron, or a-mixture of both these salts, with about 20 per cent. of
precipitated sulphate- of lime or sulphate of magnesia, the whole absorbed
intoor mixed with sufficient sawdust, spent tan, breeze, or such like porous
matter to make an open-material easily permeable by the gas, and placed on
the trays of dry lime..purifiers. When the material will no longer purify the
gis, its must be taken out of the purifyer. It will then contain a large
Price: 8d

page_text: quantity of sulphate of ammonia, but to make it still richer in this salt I
spread out and expose the material to the action of atmospheric air to oxidize
the iron of the sulphuret of iron it contains. When this is effected re-form
in the material, either partially or wholly, the same salts that were in it at
first, by adding sulphuric acid to the material. I then place the material in
the gas purifiers as at first, and pass the gas through it again. The same
effect will be produced as by the first operation, and more sulphate of
ammonia will be formed in the material. These processes of adding acid to
the material to re-form the salts, and then purifying the gas with the material
again, may be repeated until the material becomes sufficiently charged with
sulphate of ammonia. The said salts of iron may be used in this process
without the sulphate of lime or sulphate or muriate of manganese, or
sulphate of alumina may be substituted for the salts of iron, but not with so
good a result.
My second process is an improvement on a process for absorbing ammonia
into porous bodies acidified by sulphuric acid, for which obtained Letters
Patent, dated October 19th. 1848, (No. 12.290.) and the present improve-
ment consists in adding sulphuric acid to and acidifying any material composed
of sulphate of ammonia and porous material, such as sawdust, spent tan,
breeze, or such. like matter, and whether formed by my said former Patent
process or not, and then passing the gas through it until the acid added to it
is neutralized by taking up ammonia from the gas. Sulphuric acid may be
repeatedly added to such material each time after it becomes spent and ceases
to purify, and the material may then be repeatedly used again to purify gas
from ammonia until it becomes charged with sulphate of ammonia as much
as desired. Sulphuric acid may be repeatedly added as above to crystallized
sulphate of ammonia itself, so as to make a damp material, which will then
also repeatedly purify gas from ammonia. Sulphuric acid may also be
repeatedly added, as above described, to other absorbent substances, which
will then purify the gas from ammonia; but I prefer to use the salts of iron
material, described in my first process, to purify the gas and to make a
material very rich in sulphate of ammonia.
The third part of my Invention is for making the sulphate of iron material,
before described, from the residuary oxide of iron obtained after the sulphur
has been burnt off from the spent oxide of iron material which has been used
to purify illuminating gas from its sulphuretted hydrogen, by what is called
the oxide of iron process of purification, for which process obtained Letters
Patent, bearing date 28th November 1849 (No. 13,912). If the said oxide
has acquired much impurity, such as sandy or earthy matter, then the oxide

page_text: should be separated from it by putting it into a vessel, through which a
stream of water is caused to run, and floating it off while being stirred.
When the oxide is tolerably pure sulphuric acid is to be combined with it to
form the sulphates of iron. The acid acts quickest if the said oxide is
reduced to the metallic state, or to the state of protoxide, by heating it with
coals (in the state of fine powder) or other carbonaceous matter in a closed
furnace or refort. An excess of acid should be used, which should afterwards
be taken up or neutralized by lime or chalk, so as to make about 20 per
cent. of sulphate of lime in the mixture. The mixture should not be allowed
to get too thick, if it becomes so water should be added to it to keep it in a
semi-fluid or pasty state. The sulphuric acid to form the salts of iron should
be added to the oxide in a pan or in a reverberatory furnace, as heat assists
the combination of the iron with the acid. When the combination is effected
the whole is to be absorbed into or to be mixed with dry sawdust, spent tan,
breeze, or other like matter, so as to make a porous material, easily permeable
by the gas. Instead of mixing or absorbing the said salts of iron and lime
formed by the combination of the acid with the oxide of iron and lime with
any insoluble impurities that may exist in the oxide of iron, the said
impurities may be separated by means of a sand filter from the solution of
the salts of iron formed. In this case the solution of the salts of iron should
be weaker than in the former case, and the lime to take up any excess of
acid should be added to the filtered solution; after which it may be mixed
with the sawdust or other porous material, as before described.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Frank Clarke Hills in the Great Seal Patent Office on
the 27th October 1864.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, FRANK
CLARKE HILLS, of Deptford, in the County of Kent, Manufacturing Chemist,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Ifer Letters
Patent, bearing date the Twenty-ninth day of April, in the year of our Lord
One thousand eight hundred and sixty-four, in the twenty-seventh year
of Her reign, did for Herself, Her heirs and successors, give and grant
unto me, the said Frank Clarke Hills, Her special licence that I, the
said Frank Clarke Hills, my executors, administrators, and assigns, or
such others as I, the said Frank Clarke Hills, my executors;" adminis

page_text: v
trators, 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 "INPROVEMENTS IN THE PURIFICATION OF GAS, AND IN
OBTAINING A VALUABLE PRODUCT IN THE PROCESS, AND FOR THE PREPARATION
OP SOME OF THE MATERIALS TO BE USED IN THE SAID PURIFICATION," upon
the condition (amongst others) that I, the said Frank Clarke Hills,
my executors or administrators, by an instrument in writing under my, or
their, or one of their hands and seals, should 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 1, the said Frank Clarke Hills, do hereby
declare the nature the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say:
My first process is for purifying gas from its ammonia and other impurities
by passing it through a material composed of persulphate of iron, or proto-
sulphate of iron, or a mixture of both these salts, with about 20 per cent. of
precipitated sulphate of lime or sulphate of magnesia, the whole absorbed into
or mixed with suflicient sawdust, spent tan, breeze, or such like porous matter,
to make an open material easily permeable by the gas and placed on the trays
of dry lime purifiers. When the material will no longer purify the gas it must
be taken out of the purifier, it will then contain a large quantity of sulphate of
ammonia, but to make it still richer in this salt I spread out and expose the
material to the action of atmospheric air to oxidize the iron of the sulphuret of
iron it contains. When this is effected I re-form in the material, either par-
tially or wholly, the same salts that were in it at first by adding sulphuric acid
to the material; I then place the material in the gas purifier as at first, and
pass the gas through it again. The same effect will be produced as by the
first operation, and more sulphate of ammonia will be formed in the material.
These processes of adding acid to the material to re-form the salts and then
purifying the gas with the material again may be repeated until the material
becomes sufficiently charged with sulphate of ammonia. The said salts of iron
may be used in this process without the sulphate of lime, or sulphate or
muriate of manganese, or sulphate of alumina may be substituted for the salts
of iron, but not with so good a result.

page_text: My second process is an improvement on a process for absorbing ammonia
into porous bodies acidified by sulphuric acid, for which I obtained Letters
Patent dated 19th October 1848 (No. 12,290), and the present improvement
consists in adding sulphuric acid to and acidifying any material composed of
sulphate of ammonia and porous material, such as sawdust, spent tan, breeze,
or such like inatter, and whether formed by my said former Patent process
or not, and then passing the gas through it until the acid added to it is
neutralized by taking up ammonia from the gas. Sulphuric acid may be
repeatedly added to such material each time after it becomes spent and ceases
to purify, and the material may then be repeatedly used again to purify gas
from ammonia until it becomes charged with sulphate of ammonia as much as
desired. Sulphuric acid may be repeatedly added as above described to
crystallized sulphate of ammonia itself, so as to make a damp material, which
will then also repeatedly purify gas from ammonia. Sulphuric acid may also be
repeatedly added, as above described, to other absorbent substances, which will
then purify the gas from ammonia, but I prefer to use the salts of iron mate-
rial, described in my first process to purify the gas and to make a material
very rich in sulphate of ammonia.
The third part of my Invention is for making the sulphate of iron material,
before described, from the residuary oxide of iron obtained after the sulphur
has been burnt off from the spent oxide of iron material which has been used
to purify illuminating gas from its sulphuretted hydrogen by what is called the
oxide of iron process of purification, for which process I obtained Letters
Patent bearing date 28th November 1849 (No. 12.867.) If the said oxide
has acquired much impurity, such as sandy or earthy matters, they should be
separated from it. This is best done by putting the said oxide into a vessel
through which a stream of water is caused to pass and stirring the said oxide,
when it will be floated off by the said stream of water, and the impurities will
remain at the bottom of the vessel. When the oxide is tolerably pure, sul-
phuric acid is to be combined with it to form the sulphates of iron. The acid
acts quickest if the said oxide is reduced to the metallic state, or to the state
of protoxide, by heating it with coals (in the state of fine powder) or other car-
bonaceous matter in a closed furnace or retort. An excess of acid should be
used, which should afterwards be taken up or neutralized by lime or chalk, so
The
as to make about 20 per cent. of sulphate of lime in the mixture.
mixture should not be allowed to get too thick, if it becomes so water should
be added to it to keep it in a semi-fluid or pasty state. The sulphuric acid to
form the salts of iron should be added to the oxide in a pan or in a rever-
beratory furnace, as heat assists the combination of the iron with the acid.

page_text: When the combination is effected, the whole is to be absorbed into or to be
mixed with dry sawdust, spent tan, breeze, or other like matter, so as to make
a porous material easily permeable by the gas. Instead of mixing or absorbing
the said salts of iron and lime, formed by the combination of the acid with the
oxide of iron, and lime, with any insoluble impurities that may exist in the
oxide of iron, the said impurities may be separated by means of a sand filter
from the solution of the salts of iron formed. In this case the solution of the
salts of iron should be weaker than in the former case, and the lime to take
up any excess of acid should be added to the filtered solution, after which
it may be mixed with the sawdust or other porous material, as before described.
Having now described the nature of my Invention, and the manner in which
the same is to be performed, I claim as my Invention,--
First, the use of persulphate of iron, or proto-sulphate of iron, or a mixture
of both of these salts, combined with precipitated sulphate of lime or sulphate
of magnesia, for the purpose of purifying gas, as herein-before described.
And, secondly, the manufacture of the said salts of iron from the spent
oxide of iron that has been used to purify gas after the sulphur has been
burnt off from the said oxide of iron, as herein-before described.
In witness whereof, 1, the said Frank Clarke Hills, have hereunto set my
hand and seal, this Eleventh day of October. in the year of our Lord
One thousand eight hundred and sixty-four.
Witness,
H. H. MURDOCH
7, Staple Inn.
F. C. HILLS. (L.S.)