DISCLAIMER AND MEMORANDUM OF ALTERATION
Year: 1877

page_text: THEREFROM, dated the 20th January, 1877, No. 272, a portion of which
Letters Patent has been assigned to and is now vested in William
Freeman Jack, of Mark Lane, in the City of London, Accountant, and
Ebenezer Stewart and Halley Stewart, of Queen Victoria Street, in the
City of London, Merchants.
DISCLAIMER AND MEMORANDUM OF ALTERATION proposed to be
entered by the said Carl Friedrich Claus, William Freeman Jack, Ebenezer
Stewart, and Halley Stewart.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters Patent
bearing date the 20th day of January, in the year of our Lord One thousand eight
hundred and seventy seven, in the fortieth year of Her reign, did, for Herself, Her
heirs and successors, give and grant unto the said Roger William Wallace and Carl
Friedrich Claus, their executors, administrators, and assigns, the sole privilege
of making, using, exercising, and vending within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, the said Invention of
"IMPROVEMENTS IN THE PURIFICATION OF GAS, AND THE UTILIZATION OF BYE-
PRODUCTS BY THE MANUFACTURE OF SECONDARY PRODUCTS THEREFROM," for and
during the term of fourteen years thence next ensuing:
And whereas in pursuance of a proviso of the said Letters Patent the said Roger
William Wallace and Carl Friedrich Claus did within six calendar months next
and immediately after the date of the said Letters Patent cause a Specification of
the said Invention to be filed in the Great Seal Patent Office:
And whereas by assignments duly registered in the Great Seal Patent
Office the right, title, and interest of the said Roger William Wallace in and to the
D

page_text: said Letters Patent have been assigned and are now vested in the said William
Freeman Jack, Ebenezer Stewart, and Halley Stewart:
And whereas since the date of the said assignments we, the said Carl
Friedrich Claus, William Freeman Jack, Ebenezer Stewart, and Halley Stewart,
have been advised that by reason of ambiguity in the language of certain portions
of the descriptive and claiming clauses of the Specification of the said Letters
Patent the same may be construed as extending to and covering Inventions other
than that for which the said Letters Patent were granted, and such as were not
entirely or altogether new in respect of the public knowledge and use thereof at
the date of the said Letters Patent.
6
NOW KNOW YE therefore that we, the said Carl Friedrich Claus, William
Freeman Jack, Ebenezer Stewart, and Halley Stewart, by and with the consent of
Her Majesty's Solicitor General, do alter and amend the said Letters Patent and
Specification as follows, that is to say:-We strike out of the title of the said
Invention in the Letters Patent and Specification the words "and the utilization
of bye-products by the manufacture of secondary products therefrom," and referring
to the Queen's Printers copy of the said Specification, and to page 4 of the same,
we strike out of lines 9 and 10 the words "and the utilization of certain products
resulting therefrom," and we insert after the word "We," in line 11, the words
'prefer to," and we strike out the words "the said " in line 12, and the following
words to the end of line 13. We strike out the whole of the matter commencing
We strike out
with the word "Immediately," in line 15 to the end of line 20.
of line 22 the words "or liquid ammonia," and out of line 25 the word
"If" at the commencement thereof, also the words "ammonia is used in the
form of," and also the word "it." We strike out of line 28 the words " or weak
liquid." We strike out the whole of the matter from the commencement of
line 36 to the end of line 47, and we strike out of line 51 the words "that
We strike out of
is to say," and the following words to the end of line 52.
line 53 the word " employed" and the words "about 1/3 to 1/6 of an equivalent of
the," and we strike out of line 54 the words " of the corresponding quantity of," and
on page 5 we strike out of line 15 the word " either," and out of line 16 the words
as it leaves the retorts, or employ it as liquid ammonia." We strike out the
whole of the matter from the commencement of line 21 to the end of line 31. We
strike out of line 32 the word "as," and insert in line 33 after the word "process
the word "and." We also insert in line 34 after the word "we" the word "may,"
and we strike out of line 36 the word "burnt." On page 6 we strike out the
whole of the matter commencing with the words "A part of" in line 2 to the end
of line 46, and we insert after the word "that" in line 48 the following words :--
"We make no claim to the purification of gas by gaseous ammonia, or to the
production of gaseous ammonia by the decomposition of chloride of ammonium
" by lime, apart from the above described process taken as a whole, in which the
same quantity of chloride of ammonium is repeatedly used and recovered, and in
which Carbonate of Soda 18 or mav be obtained as a bye-product, but." We
"
which carbonate of soda 18 or may De obtained as & Dye-produce, ouv
YYC
strike out of line 49 the word "First" and the words " or liquid," and we strike
out the second and the whole of the following claiming clauses; and in order that
the effect of the said Disclaimer and Memorandum of Alteration may be fully
understood we annex a copy of the said Specification (omitting the introductory'
and concluding clauses thereof) as it will appear when such Disclaimer has been
made.
"The said Invention relates to the purification of gas, as hereinafter described.
"We prefer to employ instead of the scrubbers and purifiers now used square
" towers filled with angle-irons, or triangular bars of stone, stoneware, or earthen-
"
ware.
65
The gas to be purified is admitted to the bottom, and is conducted away from
" the top of the said tower.

page_text: "As the purifying agent to absorb the carbonic acid contained in the gas we
use ammoniacal gas, which we obtain by decomposing chloride of ammonium by
means of burnt or slacked lime, this chloride of aminonium being obtained in a
subsequent process hereinafter described.
"The ammoniacal gas is passed, along with the illuminating gas, through a
"number or series of the towers above described, and whatever quantity of
"ammonia remains unabsorbed is finally condensed in one, two, or more of the
"last towers of the series by a shower of water descending in the towers. This
"liquid is pumped from tower to tower in the opposite direction to that in which
"the gas travels, and the liquor resulting ultimately from this procedure, and
"which contains principally carbonate of ammonia, is drawn for further use from
"the tower, which, by reason of its favorable temperature and other conditions,
"will yield the liquid in the most concentrated form, that is to say, containing the
"greatest quantity of carbonate of ammonia; in other words, we allow a kind of
" fractionation' to take place in the towers or scrubbers.
"In the concentrated carbonate of ammonia liquor we dissolve in separate
"apparatus an equivalent quantity of chloride of sodium, then we pass a current
"of carbonic acid through the mixture, whereby, as is well known, a bi-carbonate
"of soda salt is deposited in the liquor, whilst chloride of sodium as well as
"carbonate or bicarbonate of ammonia remains in solution either as bi-carbonate
"of soda, or if heat be applied to the mixture as chloride of sodium, as will be
"understood by subsequent explanations.
"Other compounds of ammonia that may have been present in the original
"carbonate of ammonia solution employed, such as sulphide of ammonium or
sulphocyanide of ammonium, do not enter into this decomposition and remain in
"the mother liquors hereinafter specified.
"Simultaneously with the bicarbonate of soda an equivalent quantity of chloride
"of ammonium is formed as mother liquor, from which the bicarbonate of soda is
separated by filtration.
$6
By applying heat to this mother liquor we distil off the carbonate of ammonia
"contained in the same, and also the volatile sulphide of ammonium, which may
"also exist in the mother liquors, and we collect these same products to be used
again.
ス
"After the volatile compounds of ammonium have been driven off we put burnt
or slacked lime into the still, thereby producing ammoniacal gas, which we
employ in the purification of the illuminating gas, that is to say, we admit the
same into the coal-gas in the manner described.
" Instead of dissolving the chloride of sodium in solutions of carbonate of
" ammonia, as above described, concentrated or strong solutions of these salts may
may be made separately, then be mixed together, and carbonic acid injected into
the mixture.
"
"The ammonia derived from the coal-gas itself is constantly added to that
which is introduced into the circulation by our process, and the quantity
* accumulated in excess of the quantity required for the purpose of purification
we may conduct into sulphuric acid or hydrochloric acid for the manufacture of
commercial salts of ammonium.
"The chloride of calcium formed by the action of the lime on the chloride of
* ammonium may be either utilized in any convenient manner or discharged as
refuse matter.
"The bicarbonate of soda obtained in our process we heat in closed vessels,
to deprive it of one equivalent of carbonic acid, which being unmixed with other
gases we collect in a gas-holder, and force it therefrom by means of suitable
pumps into the mixture of carbonate of ammonia and chloride of sodium, as above
described.
"As an auxiliary source of carbonic acid we use that obtained by heating
bicarbonate of potash or soda after these bicarbonates have been produced from
the carbonates by means of impure carbonic acid obtained from known sources.

page_text: "
"
"The use of ammoniacal gas or liquid ammonia has been already proposed for
the purification of illuminating gas from carbonic acid, but in every instance the
proposed method of its application has involved the use of slacked lime in
"connection with ordinary gas liquor, and therefore insoluble carbonate of lime
"has been produced. This product has proved a more formidable nuisance, and
a more disagreeable residue to dispose of than that obtained from the dry lime
"purifiers now used, a fact which has hitherto prevented the application of this
" otherwise effective process of purification. In all these processes, moreover, the
"carbonic acid in the ammoniacal liquor (which in its soluble form represents a
" certain value) has been not only lost but actually converted into a source of.
annoyance.
"
<<
"One object of our Invention is to obviate these difficulties by utilizing the
"carbonic acid without producing any solid refuse, as the chloride of calcium may
"be run into sewers or rivers, in which it will act as a disinfectant.
"
"
Having thus fully described our said Invention, and the manner of performing
"the same, we wish it understood that we make no claim to the purification of gas
"by gaseous ammonia, or to the production of gaseous ammonia by the decom-*
position of chloride of ammonium by lime, apart from the above described
process taken as a whole, in which the same quantity of chloride of ammonium
" is repeatedly used and recovered, and in which carbonate of soda is or may be
"obtained as a bye product, but we claim,―
"
"E
In the purification of gas, the employment of gaseous ammonia obtained by
"the decomposition of chloride of ammonium by lime, according to the above
described process for the elimination or removal of the carbonic acid from the
gas."
Сс
In witness whereof, we, the said Carl Friedrich Claus, William Freeman
Jack, Ebenezer Stewart, and Halley Stewart, have hereunto set our hands
and seals, this Eighteenth day of August, in the year of our Lord One
thousand eight hundred and eighty one.
I hereby grant my fiat, giving leave to the above named Carl Friedrich Claus,
and William Freeman Jack, Ebenezer Stewart, and Halley Stewart (the three last
named being the assignees of a certain part of the above mentioned Letters Patent),
to file in the Great Seal Patent Office, with the Specification to which the same
relates, the above written Disclaimer and Memorandum of Alteration.
1001

page_text: LETTERS PATENT to Roger William Wallace, of the Chemical Works, New
Road, Battersea Park, in the County of Surrey, Manufacturing Chemist, and
Carl Friedrich Claus, of Great St. Helen's, in the City of London, Consulting
Chemist, for the Invention of "IMPROVEMENTS IN THE PURIFICATION OF Gas
AND UTILIZATION OF BYE-PRODUCTS BY THE MANUFACTURE OF SECONDARY
PRODUCTS THEREFROM "
Sealed the 17th July 1877, and dated the 20th January 1877.
PROVISIONAL SPECIFICATION left by the said Roger William Wallace and
Carl Friedrich Claus at the Office of the Commissioners of Patents on the
20th January 1877.
ROGER WILLIAM WALLACE, of the Chemical Works, New Road, Battersea Park,
in the County of Surrey, Manufacturing Chemist, and CARL FRIEDRICH CLAUS, of
Great St. Helen's, in the City of London, Consulting Chemist. "IMPROVEMENTS IN
THE PURIFICATION OF GAS AND THE UTILIZATION OF BYE-PRODUCTS BY THE
MANUFACTURE OF SECONDARY PRODUCTS THEREFROM."
"
We employ instead of the scrubbers now in use square towers filled with angle
irons or triangular bars of stone, stoneware, or earthenware; said angle irons or
stoneware bars are placed together closely in layers, each layer crossing the other at
right angles, and each two or three layers being supported independently by
bearing bars. The section of the angle irons presents a sharper angle than ordinary
angle iron, somewhere about 45°.
The gas is admitted into the tower by a pipe entering the tower about one foot
above the bottom, and is conducted out of the top by another pipe of equal size, or
vice versa.
The angle pieces reach from one side of the tower to the other.
The distance laterally of the same from one another should be so arranged that the
total sum of the spaces left between them is about double that of the area of the
inlet pipe of the gas.
The towers are constructed of iron plates bolted or rivetted together; they are
made much less in height than the ordinary scrubbers, but of about the same
superficial area in transverse section, and we prefer to employ a greater number of
them than the same area of ordinary scrubbers would represent. The first layer of

page_text: angle pieces begins just above the inlet pipe for the gas, and the last terminates just
below the outlet pipe on the top. The whole of the intervening space is filled with
angle pieces as described, but a vacant space is left where the upper pipe enters, equal
in depth to the diameter of the said pipe, and close above it are two more layers of
angle pieces crossing each other at right angles. These are for the purpose of
distributing the liquor in the form of rain over the layers of angle pieces below
them, and are placed very close together and at a uniformly equal distance, the
edges being for that purpose perfectly straight. Over these two layers of angle
pieces there is a so-called tumbling box into which the gas liquor or scrubbing
liquor is discharged from a pipe attached to a force pump, which carries the liquor
from a receiver placed below the tower up to the top of the same.
As a purifying agent, to absorb the carbonic acid contained in the gas as an
impurity, we use ammoniacal gas or liquid ammonia which we obtain by decomposing
chloride of ammonium by means of burnt lime, the chloride of ammonium being
obtained in a subsequent process to be described below. The ammoniacal gas is
passed along with the illuminating gas through a series of the towers described,
and is finally condensed in one or two of the last towers by a shower of weak
liquor or water descending the towers. The resulting liquor containing principally
carbonate of ammonia is pumped from tower to tower, and is drawn for further use
from the one which, by favorable temperature and other conditions, will yield the
same in the most concentrated form containing a maximum of carbonate of ammonia,
that is to say, we allow a kind of fractional distillation to take place in these
scrubbers themselves which may be aided by the application of heat from extraneous
sources. If this concentrating action of the towers should be found not sufficient
to attain the desired object, we distil the liquor in plant separate from the gas plant
in order to obtain carbonate of ammonia of the required or highest strength in the
manner known to chemists.
In the concentrated carbonate of ammonia liquor we dissolve in a separate plant
an equivalent quantity of chloride of sodium and pass a current of carbonic acid
through the mixture, whereby as is well known a bicarbonate of soda salt is
deposited in the liquor, namely, about of an equivalent of the chloride of sodium
employed, whilst of an equivalent of chloride of sodium remains in solution.
Simultaneously with the bicarbonate of soda an equivalent quantity of chloride of
ammonium is formed from which the bicarbonate salt is separated by filtration.
The carbonate of ammonia contained in the mother liquor we distill off and collect
to be used again. The mother liquor, containing chloride of ammonium and chloride
of sodium, we use instead of water for washing the illuminating gas in the towers,
and cause it to absorb fresh quantities of carbonate of ammonia therefrom. It is
then employed for dissolving fresh quantities of chloride of sodium, and further
quantities of bicarbonate of soda are manufactured from it as described above, and so
forth, the above operations being several times repeated until the proportion of
chloride of sodium is small compared to that of chloride of ammonium, when its
further use is discontinued. All carbonate of ammonia is then distilled from it
and used as above. The chloride of ammonium liquor is then run into a still and
is decomposed by means of burnt lime, ammoniacal gas is evolved thereby which
we employ in the purification of the illuminating gas as described, and whatever
ammonia accumulated in excess to that required for that purpose we conduct into
sulphuric or hydrochloric acid for the manufacture of commercial salts of ammonium.
The chloride of calcium formed in this operation may be either utilized in any con-
venient manner or discharged as waste.
The bicarbonate of soda obtained we deprive in closed vessels by means of heat
of one equivalent of carbonic acid, which being unmixed with other gases we force
into the mixture of carbonate of ammonia and chloride of sodium.
As an auxiliary source of carbonic acid we use that obtained by heating
bicarbonate of potash or soda, after said bicarbonates have been produced from the
carbonates by means of impure carbonic acid from known sources.
Ammoniacal gas or liquid ammonia has been repeatedly proposed for the purifi-

page_text: cation of illuminating gas from carbonic acid, but in every such instance the
proposed method of application involved the use of slacked lime in connection with
ordinary gas liquor, by which means insoluble carbonate of lime is produced which
proved to be a more formidable nuisance, and a more disagreable refuse to dispose
of than that obtained from the dry lime purifiers now used; a fact which has
hitherto prevented the application of this otherwise effective process of purification.
In all these processes, moreover, the carbonic acid in the ammoniacal liquor,
which in its soluble form represents a certain value, was not only lost but actually
converted into a source of aunoyance. One object of our Invention is to obviate
both difficulties by utilising the carbonic acid and not producing any solid refuse, as
the chloride of calcium may be run into sewers or rivers in which it will act as a
disinfectant.
A part of the chloride of ammonium liquor may according to our Invention also
be decomposed instead of by lime by sulphide of barium. If this decomposition is
effected by heat in a closed boiler sulphide of ammonium is volatilised which may
be condensed in acid or otherwise utilized, and chloride of barium is obtained at
the same time. By passing sulphurous acid through this sulphide of ammonium
hypo-sulphite of ammonia is produced (if the temperature of the liquor be kept
down sufficiently), which hypo-sulphite may be decomposed by sulphuric acid, and
the sulphurous acid set free may either be conducted into the lead acid chambers, or
used for the purification of gas from sulphide of hydrogen.
If the sulphide of ammonium is conducted at once into acid, we burn the
sulphide of hydrogen into sulphurous acid, and pass the latter through sulphide of
barium solutions for the production of hypo-sulphite of baryta.
We also employ solutions of sulphide of barium for the purification of gas, either
with the view of depriving the same simultaneously of its carbonic acid, and of the
sulphide or bisulphide of carbon contained therein as impurities simultaneously or
with a view of freeing it from the sulphide or bisulphide of carbon only, after
the carbonic acid and other impurities have been removed previously by other
ineans.
For the effectual working of this process the presence of sulphide of ammonia
along with sulphide of barium is essential, as it induces the formation of sulpho-
cyanide of barium by the assistance of heat. For this purpose we pass the
illuminating gas in a number of purifyng tanks or in suitable scrubbers through
the said solution of sulphides as often as is found necessary, and we use the said
solutions either cold or heated to a higher temperature. In the first process we
obtain carbonate of baryta and sulphide of ammonium, which we separate by
distillation. In the second process the sulphide of ammonium is distilled off from
the sulpho-cyanides, and the residual liquor containing the latter is used several
times over and over for dissolving fresh quantities of sulphide of barium in order to
accumulate the sulpho-cyanide of barium formed therein during the process of
purification of gas.
When the said compound has sufficiently accumulated in the liquor we proceed
to separate the same by any convenient process for the manufacture of prussiate of
baryta or potash respectively.
The
After the illuminating gas has passed and been freed in the first set of towers or
scrubbers of its carbonic acid by means of ammoniacal gas or liquor, and in the
second set of its bisulphide of carbon we proceed to purify it of the sulphide of
hydrogen contained therein by admitting sulphurous acid gas derived from the
decomposition of hypo-sulphite of baryta by means of hydrochloric acid.
sulphur separated we collect and use after having been washed and fused, as is
done in the recovery of sulphur from alcali waste. Each set of towers is worked
by itself, the last one or two being used as a washing tower; water, mother liquor,
or weak liquor being used separately for this purpose. The gas, however, passes
through all of them in an uninterrupted current.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Roger William Wallace and Carl Friedrich Claus in the Great Seal Patent
Office on the 20th July 1877.
ROGER WILLIAM WALLACE, of the Chemical Works, New Road, Battersea Park,
in the County of Surrey, Manufacturing Chemist, and CARL FRIEDRICH CLAUS, of
Great St. Helen's, in the City of London, Consulting Chemist.
"IMPROVEMENTS IN
THE PURIFICATION OF GAS AND THE UTILIZATION OF BYE-PRODUCTS BY THE
MANUFACTURE OF SECONDARY PRODUCTS THEREFROM."
The said Invention relates to the purification of gas and the utilisation of certain
products resulting therefrom, as herein-after described.
We employ instead of the scrubbers and purifiers now used square towers filled
with angle irons, or trianglar bars of stone, stoneware, or earthenware. The said
angle pieces are placed together closely in layers.
The gas to be purified is admitted to the bottom and is conducted away from the
top of the said tower. Immediately above the outlet pipe for the gas there are two
additional layers of angle pieces crossing each other at right angles, or nearly so.
These angle pieces are for the purpose of distributing the liquor. Over these two
layers of angle pieces there is a so-called tumbling box, into which the purifying
liquid is discharged from a pipe attached to a force pump which raises the liquor
from a reservoir placed below the tower to the top of the same.
As the purifying agent to absorb the carbonic acid contained in the gas we use
ammoniacal gas or liquid ammonia which we obtain by decomposing chloride of
ammonium by means of burnt or slacked lime, this chloride of ammonium being
obtained in a subsequent process herein-after described.
If the aminonia is used in the form of ammoniacal gas it is passed along with the
illuminating gas through a number or series of the towers above described, and
whatever quantity of ammonia remains unabsorbed is finally condensed in one, two,
or more of the last towers of the series by a shower of water or weak liquid
descending in the towers. This liquid is pumped from tower to tower in the
opposite direction to that in which the gas travels, and the liquor resulting ulti-
mately from this procedure, and which contains principally carbonate of ammonia,
is drawn for further use from the tower, which by reason of its favorable tem-
perature and other conditions will yield the liquid in the most concentrated form,
that is to say, containing the greatest quantity of carbonate of ammonia; in other
words we allow a kind of "fractionation" to take place in the towers or scrubbers
which may be aided by the application of heat from extraneous sources. If this
concentrating action of the said towers should be found not sufficient to attain the
desired object we distil the liquor in apparatus separate from the gas plant in order
to obtain solutions of carbonate of ammonia of the required strength in a manner
well known to chemists.
If the ammonia for the purification of gas is employed in the form of liquid
ammonia it is produced in separate apparatus by condensing the ammonia evolved
by the action of lime on the said chloride of ammonium in water or weak liquors,
and the liquid so obtained is pumped in the opposite direction to that in which the
coal gas travels from tower to tower, always keeping one, or two, or more of the last
towers or washing towers (as in the process above described) to prevent the
remaining of any of the volatilised ammonia in the coal gas. In the concentrated
carbonate of ammonia liquor we dissolve in separate apparatus an equivalent
quantity of chloride of sodium; then we pass a current of carbonic acid through the
mixture, whereby, as is well known, a bicarbonate of soda salt is deposited in the
liquor, that is to say, according to the strength of the liquors employed, from about
to about of an equivalent of the chloride of sodium employed, whilst about to
of an equivalent of the chloride of sodium as well as of the corresponding quantity
of carbonate or bicarbonate of ammonia remains in solution, either as bicarbonate

page_text: of soda, or, if heat be applied to the mixture, as chloride of sodium, as will be
understood by subsequent explanations.
Other compounds of ammonium that may have been present in the original
carbonate of ammonia solution employed, such as sulphide of ammonium or sulpho-
cyanide of ammonium, do not enter into this decomposition and remain in the
mother liquors herein-after specified. Simultaneously with the bicarbonate of soda
an equivalent quantity of chloride of ammonium is formed as mother liquor, from
which the bicarbonate of soda is separated by filtration.
By applying heat to this mother liquor we distil off the carbonate of ammonia
contained in the same, and also the volatile sulphide of ammonium which may also
exist in the mother liquors, and we collect these same products to be used again.
After the volatile compounds of ammonium have been driven off we put burnt or
slacked lime into the still, thereby producing ammoniacal gas, which we employ in
the purification of the illuminating gas; that is to say, we either admit the same
into the coal gas as it leaves the retorts or employ it as liquid ammonia in the
manner described.
We
Instead of dissolving the chloride of sodium in solutions of carbonate of ammonia,
as above described, concentrated or strong solutions of these salts may be made
separately, then be mixed together, and carbonic acid injected into the mixture.
may use instead of water the mother liquor containing chloride of ammonium
and chloride of sodium for washing the illuminating gas in the towers, and cause it
to absorb fresh quantities of carbonate of ammonia therefrom. The said liquor may
then be employed for dissolving fresh quantities of chloride of sodium, and further
quantities of bicarbonate of soda are manufactured from it, as above described, and
so forth. The above operation may be repeated once, or twice, or as often as may
be found convenient.
It is not necessary to use the mother liquor for washing the coal gas, but if it has
been used for this purpose and its use is discontinued the said liquor which, as above
stated, contained principally chloride of ammonium, is then treated as above
described.
As the ammonia derived from the coal gas itself is constantly added to that which
is introduced into the circulation by our process the quantity accumulated in excess
of the quantity required for the purpose of purification we conduct into sulphuric
acid or bydrochloric acid for the manufacture of commercial salts of ammonium. The
chloride of calcium formed by the action of the burnt lime on the chloride of
ammonium may be either utilised in any convenient manner, or discharged as refuse
matter.
The bicarbonate of soda obtained in our process we heat in closed vessels, to
deprive it of one equivalent of carbonic acid which, being unmixed with other
gases, we collect in a gas holder, and force it therefrom, by means of suitable pumps,
into the mixture of carbonate of ammonia and chloride of sodium, as above
described.
As an auxiliary source of carbonic acid we use that obtained by heating bicarbonate
of potash or soda, after these bicarbonates have been produced from the carbonates
by means of impure carbonic acid obtained from known sources.
The use of ammoniacal gas or liquid ammonia has been already proposed for the
purification of illuminating gas from carbonic acid, but in every instance the
proposed method of its application has involved the use of slacked lime in con-
nection with ordinary gas liquor, and therefore insoluble carbonate of lime has been
produced. This product has proved a more formidable nuisance and a more
disagreeable residue to dispose of than that obtained from the dry lime purifiers
now used, a fact which has hitherto prevented the application of this otherwise
effective process of purification.
In all these processes, moreover, the carbonic acid in the ammoniacal liquor
(which, in its soluble form, represents a certain value) has been not only lost, but
actually converted into a source of annoyance.
One object of our Invention is to obviate these difficulties by utilizing the

page_text: carbonic acid, without producing any solid refuse, as the chloride of calcium may
be run into sewers or rivers, in which it will act as a disinfectant. A part of
the chloride of ammonium liquor may, according to our Invention, also be
decomposed by sulphide of barium instead of by lime. If this decomposition is
effected with heat in a closed boiler sulphide of ammonium is volatilized, and may
be condensed in acid, or otherwise utilized, and chloride of barium is obtained at the
same time. By passing sulphurous acid through this sulphide of ammonium hypo-
sulphite of ammonia is produced (if the temperature of the liquor be kept down
sufficiently), which hyposulphite may be decomposed by sulphuric acid, and the
sulphurous acid set free may either be conducted into leaden acid chambers, or used
for the purification of gas obtained from sulphide of hydrogen.
If the sulphide of ammonium is conducted at once into acid we burn the sulphide
of hydrogen into sulphurous acid, and pass the latter through sulphide of barium
solutions for the production of hyposulphite of baryta.
We also employ solutions of sulphide of barium for the purification of gas, either,
1st., for depriving the same simultaneously of its carbonic acid, and of the sulphide
or bisulphide of carbon contained therein; or 2ndly., for freeing it from the sulphide
or bisulphide of carbon only after the carbonic acid and other impurities have been
previously removed by other means.
For the elimination of the sulphide or bisulphide of carbon by this process the
presence of sulphide of ammonium with the sulphide of barium is essential, as it
induces the formation of sulphocyanide of barium by the assistance of heat. For
this purpose we pass the illuminating gas in a number of purifying tanks, or in
suitable scrubbers through the said solution of sulphides, as often as is found
necessary, and we use the said solutions either cold or heated. In this process, as
used for the elimination of both the carbonic acid and the sulphide, or the sulphide
of carbon, we obtain carbonate of baryta and sulphide of ammonium, which we
separate by decantation, filtration, and distillation. In the use of this process for
elimination of the sulphide, or bisulphide of carbon only, the sulphide of ammonium
is distilled off from the sulphocyanides, and the residual liquor containing the latter
is used several times over for dissolving fresh quantities of sulphide of barium in
order to accumulate the sulphocyanide of barium formed therein during the process
of purification of the gas.
When the said compound has sufficiently accumulated in the liquor we proceed
to separate the same, by any convenient process, for the manufacture of prussiate of
baryta or prussiate of potash.
After the illuminating gas has been freed in the first set of towers or scrubbers
of its carbonic acid by means of ammoniacal gas or liquor, and in the second set of
its bisulphide of carbon, we proceed to purify it from the sulphide of hydrogen
contained therein, by admitting sulphurous acid gas derived from the decomposition
of hyposulphite of baryta by means of hydrochloric acid; the sulphur thereby set
free we collect and use, after it has been washed and fused, as in the recovery of
sulphur from alkali waste. Each set of or series of the said towers is worked by itself,
the last one or two towers of each set being used for washing; and water, mother
liquor, or weak liquor, being used separately therefor. The gas, however, passes
through all of the said towers in an uninterrupted current.
Having thus fully described our said Invention, and the manner of performing
the same, we wish it understood that we claim,-
First. In the purification of gas the employment of gaseous or liquid ammonia
(obtained by the decomposition of chloride of ammonium by lime, according to the
above-described process) for the elimination or removal of the carbonic acid from
the gas.
Second. The utilization of the carbonic acid (eliminated or removed from the gas by
the ammonia) for the production of carbonate or bicarbonate of soda by the process
above described.
Third. In the purification of gas, the elimination or removal of carbonic acid
therefrom by means of sulphide of barium.

page_text: Fourth. In the purification of gas, the elimination or removal therefrom of the
bisulphide of carbon or sulphur compounds other than sulphide of hydrogen by
means of a mixture of sulphide of ammonium and sulphide of barium, as above
specified.
Fifth. In the purification of gas, the elimination or removal therefrom of
sulphuretted hydrogen by means of sulphurous acid obtained in the manner above
specified.
Sixth. In the purification of gas, the elimination or removal of its various above-
named impurities by a process involving the separate removal of each of these
impurities by the particular means above specified.
Seventh. The removal or getting rid of the lime used in the above process in the
condition of chloride of calcium.
Eighth. The manufacture of the secondary bye-products comprising the sulpho-
cyanide of barium; the chloride of barium; the sulphide of aminonium; the
carbonate of baryta; the sulphate of ammonia and the chloride of ammonium, by
the processes above described.
In witness whereof, we, the said Roger William Wallace and Carl Friedrich
Claus, have hereunto set our hands and seals, this Twentieth day of July, in
the year of our Lord One thousand eight hundred and seventy-seven.
ROGER WILLIAM WALLACE. (L.S.)
CARL FRIEDRICH CLAUS.
(L.S.)