IMPROVEMENTS IN THE PURIFICATION OF GAS, AND IN THE EXTRACTION OF RESIDUAL PRODUCTS THEREFROM
Year: 1873

page_text: LETTERS PATENT to Augustus George Vernon Harcourt, of Ohrist
Church, in the City of Oxford, and Frederick William Fison, of
Burley in Wharfedale, and Ilkley, in the County of York, for the
Invention of "IMPROVEMENTS IN THE PURIFICATION OF GAS, AND IN THE
EXTRACTION OF RESIDUAL PRODUCTS THEREFROM.”
Sealed the 6th February 1874, and dated the 18th August 1878.
PROVISIONAL SPECIFICATION left by the said Augustus George
Vernon Harcourt and Frederick William Fison at the Office of
the Commissioners of Patents, with their Petition, on the 18th
August 1878.
We, AUGUSTUS GEORGE VERNON HARCOURT, of Christ Church, in the
City of Oxford, and FREDERICK WILLIAM FISON, of Burley in Wharfe-
dale, and Elkley, in the County of York, do hereby declare the nature
of the said Invention for "IMPROVEMENTS IN THE PURIFICATION OF GAS, AND
IN THE EXTRACTION OF RESIDUAL PRODUCTS THEREFROM,” to be as follows :-
The chionts of this Inmontion-
First, To purify illuminating gas from sulphuretted-hydrogen and

page_text: from ammonia by the application of a mixture of materials which may
bo dealt with as one substance, and used to remove both these impurities
without necessitating the employment of separate purifiers, or the
arrangement of different materials in separate layers.
Secondly. To dispense with washing or scrubbing, for the removal of
ammonia, processes which involve a loss of illuminating power.
Thirdly. To use the same quantity of oxide for any length of time.
And, Fourthly. To obtain sulphur and sulphate of ammonia by a
simple and compact process which can be carried on at the gas works,
and therefore without cost for the transport of materials.
These objects we propose to effect in the following manner :-To
purify gas from sulphuretted hydrogen we employ hydrated peroxide of
iron (herein-after termed "oxide"), and to purify it from ammonia we
employ a solution of persulphate of iron.
The Invention may be applied at once to any of the kinds of oxide;
now used.
The solution of persulphate of iron we prepare from time to time by
dissolving a part of the oxide in dilute sulphuric acid.
To apply this liquid to the removal of ammonia we sprinkle it over
the oxide during revivification, and before the oxide is replaced in the
purifier. Thus the purifier is charged with a mixture of oxide and per-
sulphate of iron, each of which acts independently. The oxide absorbs
sulphuretted hydrogen, forming sulphide of iron, water, and sulphur;
the last named substance (formed also during revivification) accu-
mulates, and after a certain proportion has been reached must be
removed as fast as it is formed. The persulphate of iron [absorbs
ammonia forming sulphate of ammonia and oxide. The sulphate of
ammonia also accumulates as the process goes on, and must be kept
down by the extraction of portions from time to time. The amount of
oxide in use remains constant since all that is removed for conversion.
into persulphate of iron is restored by the addition of the persulphate of
iron thus formed to the contents of the purifier, and its reconversion into
oxide by the action of ammonia.
..
The treatment of a part of the purifying material taken out of the
bulk of that exposed for revivification in order to remove and obtain

page_text: 0
from it sulphur and sulphate of ammonia, and to obtain persulphate.of
iron which in turn arrests ammonia and is reconverted into oxide, is the
distinctive.feature of our Invention.
The process by which this is effected consists in extracting the
material first with water, which dissolves out the sulphate of ammonia,
and next with dilute sulphuric acid, which dissolves the oxide, forming
a solution of persulphate of iron. The undissolved residue consists of
sulphur.
By evaporating the solution of sulphate of ammonia, and by washing
and drying the residue of sulphur, these substances are obtained at once
in a saleable form.
We propose further, as a desirable but not indispensable addition to
the processes already described, to convert the ammonia and ammoniacal
salts of the liquor from the condensers into sulphate of ammonia (re-
5 uniting this portion with the rest of the ammonia formed in the retorts),
by heating the liquor, by itself or mixed with lime, in a vessel through
which a current of gas passes to the purifiers.
SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said Augustus George Vernon Harcourt and Frederick
William Fison in the Great Seal Patent Office on the 13th
February 1874.
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, Augustus
GEORGE VERNON HARCOURT, of Christ Church, in the City of Oxford,
and FREDERICK WILLIAM PISON, of Burley in Wharfedale, and Ilkley,
in the County of York, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Thirteenth day of August, in the year of
our Lord One thousand eight hundred and seventy-three, in the thirty-
seventh year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto us, the said Augustus George Vernon Harcourt
and Frederick William Fison Her special licence that we, the said
Augustus George Vernon Harcourt and Frederick William Fison,..our
executors, administrators, and assigns, or such others as we, the said

page_text: Augustus George Vernon Harcourt and Frederick William Fison, our
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 "In-
PROVEMENTS IN THE PURIFICATION OF GAS, AND IN THE EXTRACTION OF RESIDUAL
PRODUCTS THEREFROM," upon the condition (amongst others) that we, the
said Augustus George Vernon Harcourt and Frederick William Fison;
"our executors or administrators, by an instrument in writing under
'our, or one of our, 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 we, the said Augustus George Vernon
Harcourt and Frederick William Fison, do hereby declare the nature
of our said Invention, and in what manner the same is to be performed,,
to be particularly described and ascertained in and by the following

page_text: The Invention may be applied at once to any of the kinds of oxide
now used.
To purify gas from ammonia we employ a solution of persulphate of
iron which is prepared from the oxide in the manner herein-after
described. This liquid, or a portion of it, we mix with the oxide on the
revivifying floor by which it is absorbed and partly dried up. When
the mixture of oxide and persulphate is replaced in the purifier it
arrests first ammonia, whereby sulphate of ammonia is formed and the
persulphate of iron is reconverted into oxide, and then sulphuretted
hydrogen which forms sulphide of iron and sulphur. The sulphur, a
second portion of which is formed during revivification, and the
sulphate of ammonia accumulate in the purifying material, and must be .
removed by the treatment of portions of the material, in the manner
herein-after described: The amount of oxide in use remains constant
since all that. is removed for conversion into persulphate of iron is
restored by the addition of the persulphate of iron thus formed to the
contents of the purifier, and its reconversion into oxide by the action of
ammonia.
The treatment of a part of the purifying material taken out of the
bulk of that exposed for revivification in order to remove and obtain
from it sulphur and sulphate of ammonia, and to obtain persulphate of
iron which in turn combines with ammonia, and is reconverted into
oxide, is the distinctive feature of our. Invention.
The process by which this is affected consists in extracting the
material first with water which dissolves out the sulphate of ammonia,
and next with dilute sulphuric acid which dissolves the oxide, forming
a solution of persulphate of iron. The undissolved residue. consists of
sulphur.
For the extraction by water of the sulphate of ammonia from the
oxide which has become charged with it, any process may be used by
which a soluble substance is washed out from a mixture with insoluble
substances. We employ a series of tanks so placed that the liquid runs
down from the uppermost successively into those below, while each
charge of oxide is placed first in the lowest tank, and thence is trans-
ferred upwards in the manner used for the extraction of carbonate of
soda. The solution of sulphate of ammonia thus obtained. is evaporated
in a pan, and the crystals removed from time to time from the mother
liquor and left to drain. -

page_text: The oxide from which the sulphate of ammonia has been washed out
is heated with sulphuric acid diluted with three or four times its volume
of water (which has been used for washing the sulphur already made)
by blowing steam into it. for about an hour. If a sufficient quantity of
water has been added to the sulphuric acid, or condensed from the steam 5
blown in to make the specific gravity of the liquid not greater than 1.2,
the solution of persulphate of iron can be drawn off after standing twenty-
four hours, the residue of sulphur having settled to the bottom of the pan.
The sulphur is then stirred up with water and transferred to a tank, in
which it is left to settle. The water from this tank which contains 1
some persulphate of iron is used, as already stated, to dilute the
sulphuric acid by which the oxide is dissolved. The sulphur aggregates
itself into a stiff clay-like deposit which is shovelled out of the settling
tank from time to time and dried. It is then in a saleable form.
In order to convert into sulphate of ammonia not only the ammonia 1
which passes into the purifiers, but also that which is arrested by the
condensers, we adopt one or other of the two following processes :—
1. The ammoniacal liquor from the condensers may be mixed with
lime, and heated in a vessel through which a current of gas passes
to the purifiers. In this case we apply all the persulphate of iron we 2
prepare to the oxide on the revivifying floor.
2. The ammoniacal · liquor from the condensers may be heated with
lime to expel its ammonia in any of the modes now commonly practised
in the manufacture of sulphate of ammonia from ammoniacal liquor,
and the ammonia and sulphuretted hydrogen thus liberated may be led 2
into a part of the solution of persulphate of iron, forming a solution of
sulphate of ammonia and a precipitate of oxide and sulphur. The
solution may be drawn or filtered off, and either evaporated at once or
brought up to a greater strength by applying it to extract sulphate of
ammonia from the oxide in the extraction process herein-before 3
described. The precipitated oxide is mixed with the bulk of dry oxide
on the revivifying floor. The remainder of the solution of persulphate
of iron is mixed with the oxide as in the first process.
Having now described and particularly set forth the nature of this
Invention, and the manner in which the same is, or may be used, or 3
carried into effect, we would observe in conclusion that we do not
confine or restrict ourselves to the precise details or arrangements which

page_text: we have described or referred to, as variations may be made therefrom
without deviating from the principles or main features of this Inven- .
tion; but what we consider to be novel and original and therefore claim
as the Invention secured to us by the herein-before in part recited
Letters Patent is, the purification of gas from sulphuretted hydrogen
and ammonia by the continuous use of the same portion of iron (alter-
nately oxide and sulphate), and the extraction of sulphate of ammonia
and sulphur by the processes substantially as herein described.
In witness whereof, I, the said Augustus George Vernon Harcourt,
have hereunto set my hand and seal, this Twelfth day of
February, in the year of our Lord One thousand eight hundred
and seventy-four.