CERTAIN IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID, CHRYSTALLIZED SODA, AND SODA ASH, AND THE RECOVERY OF A RESIDUUM OR RESIDUUMS APLICABLE TO VARIOUS USEFUL PURPOSES
Year: 1840

page_text: TO ALL TO WHOM THESE PRESENTS SHALL COME, we, HAR-
RISON BLAIR, of Kearsley, in the County of Lancaster, Manufacturing Chemist,
and HENRY HOUGH WATSON, of Little Bolton, in the County of Lancaster,
Chemist, send greeting.
WHEREAS Her present most Excellent Majesty Queen Victoria, by Her
Letters Patent under the Great Seal of Great Britain, bearing date at West-
minster, the Sixth day of April, in the third year of Her reign, did, for
Herself, Her heirs and successors, give and grant unto us, the said Harrison
Blair and Henry Hough Watson, Her special licence, full power, sole
privilege and authority, that we, the said Harrison Blair and Henry
Hough Watson, our executors, administrators, and assigns, and such others
as we, the said Harrison Blair and Henry Hough Watson, our executors,
administrators, and assigns, should agree with, and no other, from time to
time and at all times during the term of years therein expressed, should
and lawfully inight make, use, exercise, and vend, within England and
Wales and the Town of Berwick-upon-Tweed, our Invention of "CERTAIN
IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID, CHRYSTALLIZED SODA,
AND SODA ASH, AND THE RECOVERY OF A RESIDUUM OR RESIDUUMS APLICABLE TO
VARIOUS USEFUL PURPOSES;" in which Letters Patent is contained proviso
that we, the said Harrison Blair and Henry Hough Watson, shall cause a

page_text: particular description of the nature of our said Invention, and in what
manner the same is to be performed, to be inrolled in Her Majesty's High
Court of Chancery within six calendar months next and immediately after
the date of the said in part recited Letters Patent, as is and by the same,
reference being thereunto had, will more fully and at large appear.
NOW KNOW YE, that in compliance with the said proviso, we, the said
Harrison Blair and Henry Hough Watson, do hereby declare that the nature
of our said luvention, and the manner in which the same is to be performed,
is particularly described and ascertained in and by the following description
thereof, that is to say :-
Our improvements in the manufacture of sulphuric acid, crystallized soda,
and soda ash, consist,-
Firstly, in the application of a certain residuum produced in the purification
of coal gas,to effect which purpose lime, in a slacked, fallen, or powdery state,
is used, whereby the sulphur, sulphuretted hydrogen, or other compound
containing sulphur (and with which recently generated coal gas is contami-
nated) is absorbed or collected. The lime thus impregnated with sulphur is
a refuse material hitherto of very little value. From this impregnated and
refuse lime we separate the sulphur by combustion, and consequently obtain
sulphurous acid gas, which we convert into sulphuric acid either by the
ordinary known means, or by our new and improved process, which we
intend to explain in a subsequent part of this Specification. After the
refuse lime has been exposed a few days to the action of a dry atmosphere,
and spread abroad in order to dissipate the small quantity of ammonia accom-
panying it,the combustion of the sulphur contained in it is effected by placing
the said refuse lime upon the bed or floor of a furnace or oven arranged for
the purpose, which bed or floor is heated (but not to a high state of redness)
by having a fire under it, and by causing a stream of atmospheric air (which
we prefer being hot) or oxygen gas to be directed over and upon the surface
of the lime, which surface may be changed or renewed by the operator with
a rake or other utensil as often as required, and till he finds the combustion
discontinues. We prefer that, instead of the heat being applied under the
bed of the furnace, it should be thrown from the top, which we do by reversing
the construction of the last-mentioned furnace, namely, by placing an iron
plate or tile roof a foot or more above the bed of the furnace, and allowing
the flame from the fire confined by an arched flue to pass over the said roof,by
which a sufficient heat is given by radiation from the plate or tile to ignite
and burn off the sulphur. Instead of the plate or tile a brick or iron arch
may be used. The calcareous residuum from which the sulphur has been

page_text: burnt may then be removed from the furnace or oven, and replaced by a fresh
portion of the said refuse lime from coal gas works, and so on successively.
The sulphurous acid gas produced by the combustion of the sulphur we allow
to pass as from ordinary sulphur furnaces into a leaden chamber or other
receptacle wherein to be converted into sulphuric acid. The refuse removed
from the furnace or oven (after the combustion of the sulphur), and to which
we have applied the term "calcareous residuum," consisting principally of
carbonate of lime, may be applied to many purposes which calcareous earths
are applicable to, and is very suitable to be used instead of limestone or ordinary
calcined lime along with carbonaceous matteriu thedecomposition of sulphate
of soda (frequently called salt cake) during the process of the manufacture of
soda, whether that variety sold under the name of "soda ash," or that crystal-
lized carbonate of soda commonly called "crystallized soda," and to this
purpose we do apply it in the same manner and in about the same proportion
as limestone is generally applied in.
What we claim in this first part of our Invention is, the application of
the refuse lime from coal gas works, or, in other words, lime after it has
been used in the purification of coal gas from sulphur, sulphuretted hydrogen,
er other compound of sulphur, to the manufacture of sulphuric acid, and
also soda, whether "soda ash" or crystals of soda, when the same is manu-
factured through the medium of the decomposition of sulphate of soda by
carbonaceous matter. But we do not confine ourselves to any precise plan
or method of using the said refuse lime further than to obtain sulphuric acid
from the same.
We cause the sulphur to undergo combustion without
having previously expelled it by the application of an acid; nor do we limit
ourselves to the separation of the sulphur from the said refuse lime previously
to applying it (the lime) to the manufacture of soda, as it may be used for this
purpose as soon as and in the state in which it is received from the coal gas
works, thoughweprefer previously separating by combustion the sulphur from
it, and thereby rendering it doubly useful.
Our further improvements apply particularly to the manufacture of sul-
phuric acid.
Secondly, when sulphuric acid is produced byburning sulphurfrom pyritesin
the usual manner it is frequently contaminated withoxideof arsenic insolution,
which is detrimental to the use of sulphuric acid in many of the processes
to which it has to be applied. It also frequently happens that sulphuric acid
produced in the usual manner, whether by the combustion of ordinary rough
sulphur or brimstone, or that obtained from pyrites, is contaminated in a
more or less degree with one or more of the combinations of oxygen with

page_text: nitrogen, in consequence of which it is less economically applied by dyers in
forming a solution of indigo than it otherwise would be.
It is one part of our Invention to prevent the concentrated or rectified
sulphuric acid which we produce being contaminated by the injurious ingre-
dients mentioned; this we effect in the following manner:-The weak acid
being drawn off from the chamber or other vessels, we cause, either imme-
diately or after it has been in part concentrated by evaporation, a stream of
sulphuretted hydrogen gas to bubble through it, by which, if oxide of arsenic
be present, a yellow precipitate of sulphuret of arsenic, sometimes called
orpiment or king's yellow, is formed, and if the compound or compounds of
oxygen and nitrogen alluded to be present, they are decomposed, sulphurous
acid or sulphuric acid being generated in their stead. We continue causing
the sulphuretted hydrogen to bubble through the acid till it does not appear
to produce any chemical change, and till the acid, after having been cleared
by filtering or otherwise, has no bleaching action upon sulphate of indigo when
boiled therewith. When the sulphuretted hydrogen has produced the required
change the sulphuric acid is separated by filtering or decanting from any
sulphuret of arsenic which may have been formed, and then put into the
retorts or stills for final concentration or rectification, and the sulphuret of
arsenic is well washed with water in the manner in which chemists usually
wash precipitates, and then dried, after which it is fit for use for the several
purposes to which king's yellow is generally applied.
In this part of our Invention we do not claim the use of sulphuretted
hydrogen for precipitating arsenic from solution in general, nor do we claim
the manufacture of king's yellow by our operation. But we do claim the
application of sulphuretted hydrogen as an agent in preparing for concen-
tration or rectification such sulphuric acid as would otherwise be in an unfit
state for undergoing that final part of the process of its manufacture, not
confining ourselves to the precise mode which we have mentioned of applying
the sulphuretted hydrogen, for, instead of it being caused to bubble through
the liquid, the liquid may be agitated in an atmosphere of the said gas, which
will give the desired effect; and we therefore consider that the adoption of
anydirect means of bringing sulphuretted hydrogen into intimate contact with
sulphuric acid before it has undergone concentration or rectification is an
infringement on our Inventi on. Sulphuretted hydrogen for this purpose may
be produced by acting upon the waste or refuse lime (containing sulphuret of
calcium) from the manufacture of soda, and also upon the lime which has been
used in the purification of coal gas by muriatic or other acid; though the
sulphuretted hydrogen thus produced be mixed with carbonic acid it will

page_text: answer the purpose well. It must be, however, be understood that we lay no
claita to these means of producing sulphuretted hydrogen for our purpose.
We prefer producing our sulphuretted hydrogen by one of the following
methods :-
First method. We cause aqueous vapour (steam) to pass over iron pyrites,
or any refuse iron pyrites, kept red hot in a vessel, into the interior of which
atmospheric air is not allowed to enter during the operation, which vessel may
be of cast iron, and similar to the retorts in which coal gas is generated. The
outlet for the sulphuretted hydrogen generated should, however, be at the
further end of the said retort (and not near the door), so as to cause the
steam to come into contact with a great extent of red hot surface of the said
pyrites or refuse pyrites; or, instead of an iron vessel of this kind, an oven,
or other vessel or furnace formed of bricks, and which can be kept at a red
heat by a fire outside, may be used. When sulphuretted hydrogen is
produced by these ineans it is accompanied at the commencement of the
operation by sulphurous acid gas and by some uncombined sulphur, and
therefore we find it advantageous to allow the products generated to traverse
along trough or passage kept cool, in which the uncombined sulphur deposits,
and thence to let the gases enter a sulphuric acid chamber, or furnace, or
oven, by which such a chamber obtains its supply of gas, until we find, on
testing with a salt of lead, in the manner well known to chemists, that
sulphuretted hydrogen constitutes a large portion of the gas under preparation,
at which time we turn its course, and cause it to bubble through, or be other-
wise brought into contact with, the sulphuric acid which we wish to prepare
for concentration or rectification, and the residuary gas that, unabsorbed by
the said sulphuric acid, we allow to enter a sulphuric acid chamber or
chamber furnace. We would remark, in order to make it understood, what
we mean by "refuse iron pyrites," that by the ordinary method of using
pyrites in the manufacture of sulphuric acid, viz, the causing sulphur to burn
from it (the pyrites), broken into small pieces, which are placed in a furnace,
and exposed, while at a high temperature, to a draught of atmospheric air, it
is not practicable to expel all the sulphur, and that the iron of the pyrites still
retains a large portion of sulphur when taken out of such furnace. Now, it is
thispartly decomposed pyrites which(after being discharged fromthefurnace, or
other vessel or apparatus in which it has been exposed to the action of atmo-
spheric air at a high temperature, and put aside as useless for the same kind of
action)we call "refuse iron pyrites;" or, instead of passing aqueous vapour over
the iron pyrites, or the refuse pyrites, as before mentioned, we cause hydrogen
gas(whichmaybeproducedsufficiently purebypassingaqueousvapourovercoke

page_text: or other carbonaceous matter, kept red hot, to pass over and among the said
Fyrites, or refuse pyrites, kept red hot in such apparatus, as we have mentioned
or alluded to in reference to the application of aqueous vapour to the said
pyrites or refuse pyrites. Next method:-We mix iron pyrites or the refuse
pyrites in fine powder with lime, which should be reduced to the fallen or
powdery state in the usual manner with water, or with lime in combination
with carbonic acid; chalk will do, or the refuse lime from coal gas works either
before or after the sulphur has been separated from it by combustion, in the
manner described in a former part of this Specification. The mixture we
make into a paste with water (though it is not indispensable to do so), and
then make it red hot in an iron retort or other vessel, into the interior of
which atmospheric air is not allowed to enter during the operation. When
we are sure that the mixture has been throughout red hot for about half an
hour, we withdraw it from the hot apparatus, and allow it to cool, to hasten
which it is well to slake it with water to prevent the oxidation of the sulphur.
The quantity of lime or carbonate of lime, which we prefer being mixed in the
above operation with a given quantity of pyrites or refuse pyrites, is a relative
or atomic proportion, speaking in relation to the quantity of sulphur which the
pyrites or refuse pyrites has been found by analysis to contain; that is, if it
contains thirty-two per cent. of sulphur, we would mix with every one hundred
parts by weight of it 56 of lime, or one hundred of carbonate of lime.
will add here, that, in using the refuse pyrites, we advise that there should be
mixed with it, besides the lime or carbonate of lime, before being made into a
paste with water, about one fourth of its weight of coal, which in the sub-
sequent application of a red heat tends to decompose the oxide of iron which
it contains. The calcined mixture, when cooled, we put into a still or other
suitable vessel, and pour upon it therein a quantity of muriatic or diluted sul-
phuric or nitric acidoraceticacid, whensulphurretted hydrogen gas iscopiously
disengaged, which we conduct to the sulphuric acid, which we wish it to pre-
pare for concentration or rectification. In addition to the use mentioned
which we make of the sulphuretted hydrogen produced from iron pyrites or
the refuse pyrites, as explained in stating ourseveral methods, by the foregoing,
when we do not want it for the said use (namely, the preparing sulphuric
acid for concentration or rectification), we cause it (the sulphuretted hydrogen),
issuing from a pipe connected with the generating apparatus, or with a reser-
voir or gasholder, to which it may have been transferred, to undergo com-
bustion in the oven or furnace (where it finds a supply of atmospheric air),
from which the leaden chamber or other receptacle is supplied with sulphurous
acid gas for the formation of sulphuric acid, or else we use it in the formation
We

page_text: of hydro-sulphuret of lime for the purpose mentioned in a following part of
this Specification. In producing our sulphuretted hydrogen by the last-
mentioned method, namely, by causing an acid to act upon the compound
formed by heat from iron pyrites, or refuse pyrites, and lime or carbonate
of lime, we obtain or recover two valuable residuums, one a solution of the
protoxide of iron by the acid employed, and which, though it be mixed with a
solution of the lime by the acid employed, yet is useful for many purposes in
the arts, which salts of the protoxide of iron are applicable to the other, being
a sulphureous residuum left undissolved by the acid, and which we use in
the same manner as we use the refuse lime from coal gas works, by which
we effect the combustion of the sulphur contained in it, and then apply the
sulphurous acid product to the formation of sulphuric acid.
It must be understood that we claim in this part of our Invention the appli-
cation of heated iron pyrites, or refuse iron pyrites, in the manner mentioned
withaqueousvapourorhydrogen gas intheproduction of sulphuretted hydrogen,
to be used in the manufacture of sulphuric acid, not confining ourselves to any
particular form or arrangement of apparatus to beused forobtaining the same.
And we also claim as part of our Invention the application of the calcined
compound or compounds, formed from lime or carbonate of lime, and iron
pyrites, or refuse iron pyrites, with acid, in the production of sulphuretted
hydrogen, when it is to be used in the manufacture of sulphuric acid, without
confining ourselves to any particular apparatus respecting the same, or to the
exact proportions mentioned of the ingredients, and whether the same may
have been made into a paste with water before being calcined or otherwise.
Thirdly, this part of our Invention consists in applying by combustion the
sulphur contained in hydro-sulphuret of lime(or the compound formed by sul-
phuretted hydrogen being brought into contract with hydrate of lime), to the
manufacture of sulphuric acid, and in applying the "calcareous residuum,"
produced by the abstraction of the said sulphur to the decomposition of sul-
phate of soda in the manufacture of soda ash, or crystals of soda. The means
which we recommend to be adopted whereby to produce hydro-sulphuret of
lime are as follows:-Sulphuretted hydrogen, whether pure or mixed with
other gases, and from whatever source it be produced, should be caused to
pass through a pipe or the like to a vessel containing hydrate of lime (lime
reduced to a fallen or powdery state by water) which vessel should be similar
to those used in purifying coal gas, by what is frequently called the "dry
lime purification." The hydrate of lime should be arranged in the vessel
in a manner similar to that adopted in the purification of coal gas; so
also should the sulphuretted hydrogen be admitted into the interior of the

page_text: vessel in the same manner as if it was coal gas admitted to undergo
the process of purification. The hydrate of lime having a chemical
affinity for the sulphuretted hydrogen will arrest it in its passage, and form
the compound required, and any gas or gasses which might have been
mixed with the sulphuretted hydrogen, and which are not absorbable by
hydrate of lime, will pass through the said hydrate of lime or the hydro-
sulphuret of lime, and escape from the vessel as coal gas passing off from the
purifyer. It will be known when the hydrate of lime is sufficiently impregnated
with sulphuretted hydrogen by that gas being detected passing through the
lime and off the vessel without being absorbed. It is well to use several of
the vessels connected together and arranged, as if forthepurificationof coal gas,
namely, so that that in which the state of the lime is the nearest the point of
saturation with the sulphuretted hydrogen is the one into which the said gas
enters first from the vessel in which it is generating or being transferred from.
The hydro-sulphuret of lime having been produced, we use it in the manu-
facture of sulphuric acid in the same manner as we use the refuse lime from
coal gas works, by which we effect the combustion of the sulphur contained in
it, as we have described in the preceding part of this Specification in explaining
our Invention in reference to the application of the said refuse lime from coal
gas works. Having burnt off the sulphur constituent of the hydro-sulphuret:
of lime, the calcareous residuum or refuse we use instead of limestone cr
ordinary lime with carbonaceous matter in the decomposition of the sulphate
of soda in the manufacture of soda, as we use that calcareous residuum
resulting from our operation of burning the sulphur from the refuse lime
from coal gas works, in the manner explained in the preceding part of this
Specification.
It must be understood, that in this part of our Specification, we do
not claim as our Invention the manufacture of hydro-sulphuret of lime, nor
the use of any particular arrangement of apparatus, nor of any ingredient or
ingredients in the formation of it. But that we do claim the using by combus-
tion in the manufacture of sulphuric acid the sulphur contained in hydro-
sulphuret of lime, or in the compound formed by the absorption of sulphuretted
hydrogen by hydrate of lime; and that we also claim, in the manufacture of
soda, the use of the calcareous residuum left, after as much sulphur has been
burnt off from the said compound as it is practicable to burn off.
Fourthly, the next part of our Invention consists in applying a residuumor
residums, or part of a residuum or residuums, by combustion to the manu-
facture of sulphuric acid, when sulphuretted hydrogen gas is produced, by
muriatic acid (hydro-chloric acid), carbonic acid, or other acid, being caused to

page_text: act upou the waste or residuum (in a moist state) resulting from the manu-
facture of soda, and to form which lime has been one of the constituents ofthe
mixture used. In effecting the decomposition of the sulphate of soda,a quantity
of sulphur is deposited in or among that portion of the ingredients which the
acid agent does not dissolve nor cause to be dissipated; this undissolved
residuum, either after being washed with water or unwashed, we submit to the
action of heat, either in a furnace or oven, similar to that in which we effect
the combustion of the sulphur. from the refuse lime from coal gas works, or in
any other convenient furnace, and allow the admission of atmospheric air by
which the sulphur undergoes combustion, and the sulphurous acid gas pro-
duced is allowed to pass into the chamber or receptacle, wherein its further
conversion into sulphuric acid is to proceed. When sulphuretted hydrogen
gas is produced by carbonic acid or other acid being caused to act upon the
compound (after it has been allowed to absorb moisture) formed by the
decomposition of sulphate of soda, effected by exposing that salt mixed with
carbonaceous matter (but without lime) to the action of a red heat, a
quantity of sulphur is deposited, as well as sulphuretted hydrogen gas expelled,
and a salt consisting of soda and the acid agent employed is formed; this salt,
being soluble in water, may be washed away (and, as it is a valuable one, may
be preserved for use in the manufacture of soda) from the deposited sulphur
and the other insoluble matter; the washed insoluble residuum may be then
dried, and afterwards used in the same manner as the residuum formed after
the action of acid upon the "waste" resulting from the decomposition of
sulphate of soda effected by the aid of lime, whereby the sulphur will form
sulphurous acid by combustion, and subsequently undergo the further conver-
sion into sulphuric acid.
In this part of our Specification we do not claim as our Invention the
formation of sulphuretted hydrogen by the means mentioned, nor the use
of that gas, nor the production of soda, nor any salt of soda. But we do claim
the application by combustion of the insoluble residuum or residuums,or part
of each of the said residuums, produced by the means mentioned in the
manufacture of sulphuric acid.
Fifthly, this part of our Invention consists in causing the several gasses, or
the gaseous or vapourous mixture, commonly used in the manufacture of
sulphuric acid, to act more speedily in effecting the change from sulphurous
to sulphuric acid, than what has hereto been general in the manufacture of
sulphuric acid. In the ordinary process adopted for the manufacture of
sulphuric acid, sulphurous acid gas, nitric or nitrous acid vapour (produced
by heating a mixture of nitrate of potash, or nitrate of soda and sulphuric

page_text: acid), or one or more of the other combinations of oxygen with nitrogen
and atmospheric air with some aqueous vapour, are allowed to mingle in a
leaden chamber, and to pass through that into one or more other chambers
successively, until the operator thinks fit to allow the gaseous or vaporous
residuum to pass away and diffuse itself into the atmosphere, to which it gives
a corrosive action. During the passage of the said gaseous or vaporous mixture
through the several chambers, the sulphurous acid gas slowly combines with
an additional quantity of oxygen, and becomes sulphuric acid, in which state
the greater portion gradually deposits in the chambers; but unless the
chambers connected together are numerous or very long, a considerable portion
of sulphuric acid (or at least a considerable portion of the several gasses
requisite for its formation) passes away into the atmosphere with the
gaseous or vaporous residuum, and is lost. We avoid this loss, and more
speedily produce the acid desired, thus:-As soon as or at any time after
the several gasses (or mixture of gasses and vapour) have had time to be inti-
mately diffused among each other, either in a chamber such as is generally
used, or in one of a smaller size, or in any other receptacle, we expose the
mixture to a red heat, or to a temperature nearly approaching redness, by
causing it to pass through a pipe heated red hot, or nearly so, which pipe may
be filled with siliceous stones or other articles not materially acted upon by the
heat or the acid, whereby we get an increased amount of red hot surface. The
said pipe may be of platinum, or earthenware or even of cast iron, or through
a flue-like passage, or other arrangement of brick work, kept similarly heated,
the consequence of which is, that sulphuric acid is immediately formed, and
passes away from the heated apparatus in the state of vapour, or having a
fog-like appearance, This newly-formed sulphuric acid we cause to be
condensed into a liquid state by allowing aqueous vapour to mix with it, as it
passes away from the heated apparatus, and we cause the mixture to pass
through a leaden worm kept cool by water outside, as in condensing after
ordinary distillation. The dilute acid thus formed we collect or cause to run
into a boiler or still of lead or platinum, or other suitable material, which we
keep heated so as to concentrate the acid, and so arranged as that the aqueous
vapour expelled from the said acid during concentration can be conveyed to
the extremity of the hot apparatus abovementioned, instead of steam produced
in a direct manner from pure boiling water, and there mix with fresh uncon-
densed sulphuric acid, thereby being the means of making the process
continuous without the continual, or at least extensive, addition of steam from
a fresh supply of water; or, instead of aqueous vapour being used to condense
the acid to a liquid state, other means may be adopted, viz., the vapour or fog-

page_text: like body of acid may be caused to pass up through a long leaden or other
suitable pipe or chaunel, or series of the same, placed vertically, and filled with
siliceous pebbles, which may be kept wet by water or unconcentrated liquid
sulphuric acid caused to descend in a slender stream through and among them,
whereby it (the liquid) will absorb the vapour or fog-like body of acid, and
acquire increased strength or per-centage of acid. The same acid liquor may
be caused repeatedly to pass through the pipe, pipes, or other channels, until it
has acquired a considerable degree of concentration, or until the operator thinks
it prudent to remove it for full and final concentration in the usual manner by
evaporation.
We would have it to be understood that in this part of our Specification we
do not claim as our Invention any particular arrangement of apparatus, nor the
use of any particular materials of which the apparatus may be formed, northe
use of any of the ingredients whereby or whereof the acid is formed, nor any par-
ticular means of condensing the acid when formed. What we do claim is, the
submitting or exposing to a red heat, or to a temperature nearly approaching
redness, the mixture of the several ingredients, and which are in frequent use in
the manufacture of sulphuric acid in the ordinary manner. Our claim does not
extend to the application of the said high temperature, except when the gaseous
or vaporous mixture contains either nitric acid vapour, nitrous acid vapour,
hyponitrous acid, nitrous gas, or nitrous oxide. It must also be distinctly
observed that we do not limit our claim to the high temperature when the
said gaseous or vaporous mixture has been confined to one chamber or
receptacle only, but that it also extends to the application of the high tem-
perature to what is by some called the "waste gasses" from the chambers,
that is, to the gaseous or vaporous residuum, which is, after having traversed
through more chambers than one on the at present generally practised
plan of making sulphuric acid, because, by its application to such resi.
duum, we obtain a quantity of sulphuric acid which would otherwise
have been lost, and at the same time prevent that usual residuum which
has hitherto been deleterious to animal and vegetable life from passing into
the atmosphere.
We will here remark, that, instead of either of the plans being adopted
which we have mentioned for condensing the vapour or fog-like body of
sulphuricacid, when formed, the said vapour or fog-like body may be allowed
to pass into a leaden chamber, such as those in ordinary use, or through a
succession of them (upon the floors of which there is water or dilute sulphuric
acid), until condensed; by the adoption of this means a great advantage will be
found over the old plau, inasmuch as the chambers will not so soon become

page_text: out of repair, because of the absence of nitricor nitrous acid fumes, which have
a strongly corrosive action upon lead.
In witness whereof, we, the said Harrison Blair and Henry Hough
Watson, have hereunto set their hands and seals, this Third day of
October, in the year of our Lord One thousand eight hundred and
forty.
Extray. in Chancery.
AND B
REMEMBERED, that on the same Third day of October, in
the year above mentioned, the aforesaid Harrison Blair and Henry Hough
Watson came before our Lady the Queen in Her Chancery, and acknowledged
the Specification aforesaid, and all and every thing therein contained, in form
above written. And also the Specification aforesaid was stamped according
to the tenor of the Statute in that case made and provided.
Inrolled the Sixth day of October, in the year above written.