IMPROVEMENTS IN PURIFYING GAS, ALSO APPLICABLE IN OBTAINING OR SEPA- RATING CERTAIN PRODUCTS OR MATERIALS FROM GAS WATER AND OTHER SIMILAR FLUIDS
Year: 1850

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
CORMACK, of King Street, Dunston Road, Haggerstone, in the County of
Middlesex, Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent under the Great Seal of the United Kingdom of Great Britain and
Ireland, bearing date at Westminster, the Twenty-first day of February, in the
thirteenth year of Her reign, did give and grant unto me, the said William
Cormack, my exors, admors, and assigns, Her especial licence, full power,
sole privilege and authority, that I, the said William Cormack, my exors,
admors, and assigns, and such others as I, the said William Cormack, my
exors, admors, or assigns, should at any time agree with, and no others,
should and lawfully might make, use, exercise, and vend my Invention
of "IMPROVEMENTS IN PURIFYING GAS, ALSO APPLICABLE IN OBTAINING OR SEPA-
RATING CERTAIN PRODUCTS OR MATERIALS FROM GAS WATER AND OTHER SIMILAR
FLUIDS," within that part of the United Kingdom of Great Britain and
Ireland called England, Her Dominion of Wales, and Town of Berwick-
upon-Tweed, during the term of fourteen years thence next ensuing; in
which said Letters Patent there is contained a proviso requiring that I,
the said William Cormack, shall particularly describe and ascertain the
nature of my said Invention, and in what manner the same is to be per-
formed, by an instrument in writing under my hand and seal, and cause
the same to be enrolled in Her said Majesty's High Court of Chancery
within six calendar months next and immediately after the date of the said

page_text: Letters Patent, as, reference being thereunto had, will more fully and at large
appear.
NOW KNOW YE, that in compliance with the said proviso, I, the said
William Cormack, do hereby declare that the nature of my said Invention,
and the manner in which the same is to be performed, are particularly
described and ascertained in and by this present Specification or Instrument in
writing, as follows (that is to say) :-
My said Invention consists of a mode or modes of applying certain
materials herein-after described, to purify or free coal gas (such as com-
monly burnt for the purpose of illumination) from the ammonia and sul-
phur, or sulphuretted hydrogen (either combined or otherwise), by which it
is usually contaminated before the purification thereof; and such materials are
applicable in obtaining or separating certain products or materials, not only
from gas, but also from gas water, or other similar fluids holding hydro-
sulphuret of ammonia, or 'ammonia and sulphuretted hydrogen in solution.
The materials which I use for these purposes are two salts of the descriptions
following (that is to say):-The one of such materials is a metallic salt (not a
chloride) the base of which is capable of being precipitated in the state
of a metallic sulphuret by the sulphur or sulphuretted hydrogen contained
amongst the impurities of the gas; and the other of such materials is such a
salt, of the description commonly called muriates, as shall be capable of
decomposing the ammoniacal salt resulting from the combination of ammonia
with the acid of the other salt, which may be used as one of the materials.
The salt (which (in consequence of its cheapness) I prefer to use as the
material for taking up or abstracting the sulphur or sulphuretted hydrogen
from the gas or other fluid is protosulphate of iron, commonly called green
sulphate of iron or green copperas, but any other of the soluble metallic salts
which are sufficiently cheap to be used for this purpose, and the gases of which
are known to be capable of being precipitated in the state of metallic sulphu-
rets by the sulphur or sulphuretted hydrogen contained amongst the impurities
of gas, may be used in lieu of the protosulphate of iron. The salt which (in
consequence of its cheapness) I prefer to use as the material for decomposing
the ammoniacal salt resulting from the combination of ammonia with the acid
of the other salt, which may be used as one of the materials, is chloride of
sodium, usually called muriate of soda, or common salt, but any other cheap
soluble salt may be used which is of the description commonly called muriates,
and which is known to be capable of producing such decomposition as lastly
herein-before mentioned.
To prevent confusion, I will describe my said Invention as performed by

page_text: means of those materials or salts which by reason of their cheapness I prefer to
use. When I intend to use the materials in a state of solution for purifying
gas, I take about one hundred and forty pounds of protosulphate of iron, and
seventy-four pounds of common salt, and dissolve them in about one hundred
and fifty gallons of water. The protosulphate of iron in this mixture being in
excess, for the reason herein-after mentioned, I pour this solution into a vessel,
such as usually called a purifier, and then cause the gas to pass through the
liquid in the like manner as the gas is caused to pass through milk of lime in
the well-known process of wet-lime purification. The gas in passing through
this purifier will be purified or freed from sulphur and amnionia, both of these
materials being abstracted from it and absorbed by the solution through which
it passes. This action of the solution upon the gas passing through it will con-
tinue until the dissolved materials have become decomposed or exhausted, when
it will become incapable of purifying any more gas, and this exhaustion of the
materials may be ascertained by means of the well-known tests of acetate of
lead and turmeric paper. When the purifying liquor has thus become
exhausted, the contents of the purifier are to be withdrawn and replaced by a
fresh quantity of a similar solution. The exhausted purifying liquor thus
withdrawn will contain sal-ammoniac and sulphate of 'soda in solution, and an
insoluble sediment (I presume to be sulphuret of iron), which, after the liquor
has stood some time, will settle and be deposited at the bottom of the vessel in
which it may be contained. For the purpose of obtaining the sal-ammoniac
and sulphate of soda separate from each other, the clear liquor should be
decanted from the deposited sediment just mentioned and put into evaporating
pans, and after the superfluous water has been expelled by heat (which is
known by a pellicle beginning to form at the surface of the liquid) the liquid
is to be drawn off into coolers, and in due time the sal-ammoniac will chrystal-
lize, and the sulphate of soda remaining in solution is to be decanted or drained
from the chrystals of sal-ammoniac. This is a well-known process for separating
these two salts, and need not be further described as it forms no part of my
Invention. But I may observe that. I deem it inexpedient to allow the liquor
in the coolers just mentioned to cool below a temperature of seventy-six
degrees of Fahrenheit's thermometer, lest some of the sulphate of soda should
chrystallize, and thus become mixed with the 'sal-ammoniac and deteriorate
that material. The sulphate of soda remaining in the solution after the
separation of the sal-ammoniac may also be obtained by chrystallization
in the usual manner if desired. The insoluble sulphuret already mentioned
may also be dried and obtained in a separate state if desired. Instead

page_text: of using the materials which I have described in a state of solution
for purifying gas, they may be used in a manner similar to that in
which lime is used in the ordinary process of dry-lime purification. For
this purpose I take like quantities of the protosulphate of iron and common
salt as already mentioned, reduce them to a state of powder, and mix them
with two bushels and a half of granulated animal or vegetable charcoal, and
sufficient water (from about ten to fifteen gallons) to give the mixture a soft
consistence. I then thoroughly incorporate these materials together, so as to
be of uniform consistence, and introduce a portion of the composition into the
purifier in like manner as if it were lime, and the gas passing through it will
be purified or freed from sulphur and ammonia in like manner as herein-before
described. When a portion of this purifying mixture has been exhausted the
contents of the purifier must be withdrawn, and they will be found to contain,
as before, sal-ammoniac, sulphate of soda, and an insoluble sulphuret, but mixed
with the charcoal which is used in performing the process in this way. To the
materials withdrawn from the purifier should be added sufficient water to
dissolve the sal-ammoniac and sulphate of soda, and the solution decanted from
the insoluble matters, after which the two salts may be obtained in like manner
as herein-before described.
The salts or materials which I have above described may also be employed
in any other convenient manner,. for the purpose of purifying or freeing gas
from sulphur and ammonia. Thus, for example, a solution of the proto-sulphate
of iron and common salt (in the before-mentioned proportions, may be used in
the following manner :-Take a sufficient quantity of wool or flock, such as
used in making bed mattresses, and cause it to be thoroughly soaked with the
purifying liquid, and then place it upon sieves in a purifier, in like manner as
lime is placed upon sieves in the process of purifying gas by the dry-lime
purification. The gas which is to be purified must then be caused to pass
through the saturated wool or flock, by which means it will be purified or
freed from sulphur and aminonia, in like manner as before described. When
this mode of applying the purifying liquid is adopted, such a stream of the
purifying liquid may be caused to flow down through the purifier as will be
sufficient to keep the layers of wool or flock moistened with the quantity of that
liquid which shall be requisite to purify the gas passing through the purifier.
The products of this process will of course be the same as already mentioned,
and they may be separated from each other, and obtained in like manner as
herein-before described. If any other metallic salt should be used in lieu of the
protosulphate of iron in purifying gas in manner herein-before described, such a

page_text: quantity of the substituted salt must be used as shall be equivalent to the quan-
tity of protosulphate of iron in lieu of which it shall be used (that is to say),
such a quantity of the substituted salt must be used as shall have a metallic
base capable of combining with the like quantity of sulphur or sulphuretted
hydrogen, as the base of the protosulphate of iron in lieu of which it shall
be used. And if any other salt (which must be, of course, a muriate) should
be used in lieu of common salt in purifying gas, in manner aforesaid, such a
quantity of the substituted salt must be used as shall be equivalent to the
quantity of common salt in lieu of which it shall be used (that is to say),
such a quantity of the substituted salt must be used as shall contain (in
combination with its base), the same quantity of chlorine as the quantity of
common salt in lieu of which it shall be used. I have stated the propor-
tions of salts which I deem to be the best to be used in purifying gas of the
description most generally made; but the quantities and proportions of the
impurities contained in gas depend (in a great measure at least) upon the
quality and description of coal from which it is obtained, and therefore it must
be understood that the proportions of the salts may be varied or modified, as
may be requisite, according to circumstances. In the proportions of the
inaterials which I have herein-before mentioned, the protosulphate of iron,
or other salt used in lieu of it, will be in considerable excess, for the propor-
tions of protosulphate of iron and common salt proper for decomposing
hydrosulphuret of ammonia are seventy-six parts by weight of protosulphate
of iron to sixty parts by weight of common salt. I believe (judging from
experience) that an excess of the metallic salt, such as I have mentioned,
will be found useful in purifying gas; but I do not intend to say that such
an excess is absolutely necessary in every case. And it is to be observed,
that a small excess of either of the two salts which may be used in purifying gas
will not prevent or retard the purification of the gas, and the chief if not the
only evil will be, that the portion of salt which may be in excess will be mixed
with the products or materials remaining in the purifier when the purifying
power of the mixture of salts has been exhausted. And it must also be
observed, that if any such other salts as aforesaid shall be substituted either
for protosulphate of iron or common salt used in purifying gas, in manner
aforesaid, although sal-ammoniac will still be produced, the other products or
materials resulting from the performance of the process of purifying, or some
of them, will be different. And such other products or materials which shall
remain when the mixture of purifying materials shall have become exhausted,
may be separated by evaporation and crystallization, or in any other con-

page_text: venient manner; but the mode of separating such materials (as already
stated) forms no part of my said Invention. Gas purified in the manner
already described may be purified from carbonic acid by causing it also to
pass through lime; but such further purifying process forms no part of my
Invention. The compound or combination of materials which I have above
described for purifying gas and obtaining various products or materials there-
from as aforesaid, may also be used or applied in obtaining or separating
sulphur or sulphuretted hydrogen and amnionia from gas-water or ammo-
niacal liquor, or from any other liquid containing those materials. For this
purpose I take protosulphate of iron and common salt in the before-men-
tioned proportions, and either in a state of solution or powdered, and
thoroughly mixed together, and add it gradually to the liquid to be operated
upon, continuing from time to time to add further portions of the materials
until the whole of the sulphur .or sulphuretted hydrogen and ammonia have
been separated, which may be ascertained by means of acetate of lead and
turmeric paper, the tests already mentioned. The liquid may then be decanted
from the insoluble material which will have been formed, and the soluble
salts may be separated from each other and obtained in like manner, as
already described. And for the purpose of obtaining or separating sulphur
or sulphuretted hydrogen and ammonia (in a combined state) from gas-water,
ammoniacal liquor, or any such other liquid as aforesaid, other salts may be
substituted for the protosulphate of iron and common salt respectively in
like manner as herein-before mentioned, and the products or materials
resulting from the performance of every such process may also be separated
in like manner; as herein-beforé described or mentioned.
Having now described the nature of my said Invention, and the manner
in which the same is to be performed, I hereby declare that I claim as of my
Iuvention the application of a combination or joint application of such salts
or materials as aforesaid, in the purifying or freeing gas from sulphur and
ammonia, in manner herein-before described; and also in the obtaining or
separating such products or materials as aforesaid from gas, gas-water,
ammoniacal liquor, or other liquid containing sulphur and ammonia, as
aforesaid..
In witness whereof, I, the said William Cormack, have hereunto set
my hand and seal, this Twenty-first day of August, in the year of
W CORMACK. (LS.)

page_text: AND BE IT REMEMBERED, that on the Twenty-first day of August,
in the year of our Lord 1850, the aforesaid William Cormack came before
our said Lady the Queen in Her Chancery, and acknowledged the Specifi-
cation aforesaid, and all and every thing therein contained and specified,
in form above written. And also the Specification aforesaid was stamped
according to the tenor of the Statute made for that purpose.
Enrolled the Twenty-first day of August, in the year of our Lord One
thousand eight hundred and fifty.