IMPROVE- MENTS IN TREATING AND UTILIZING CERTAIN MATERIALS USED AND PRODUCTS OBTAINED IN THE MANUFACTURE OF GAS, AND IN APPARATUS CONNECTED WITH THE SAID TREATMENT
Year: 1862

page_text: LETTERS PATENT to William Cleland, of 39, St. George's Hill, Everton,
Liverpool, in the County of Lancaster, for the Invention of "IMPROVE-
MENTS IN TREATING AND UTILIZING CERTAIN MATERIALS USED AND PRODUCTS
OBTAINED IN THE MANUFACTURE OF GAS, AND IN APPARATUS CONNECTED WITH
THE SAID TREATMENT."
Sealed the 8th July 1862, and dated the 15th January 1862.
PROVISIONAL SPECIFICATION left by the said William Cleland at the
Office of the Commissioners of Patents, with his Petition, on the 15th
January 1862.
I, WILLIAM CLELAND,' of 39, St. George's Hill, Everton, Liverpool, in the
County of Lancaster, do hereby declare the nature of the said Invention
for "IMPROVEMENTS IN TREATING AND UTILIZING CERTAIN MATERIALS USED AND
PRODUCTS OBTAINED IN THE MANUFACTURE OF GAS, AND IN APPARATUS CONNECTED
WITH THE SAID TREATMENT," to be as follows:-
My improvements relate, firstly, to the extraction of ammonia and sulphur
from bog iron ore and other "oxides" that have been used for purifying gas.
I effect this by distillation or sublimation, and in general find it most con-
venient to employ retorts somewhat similar to those used in the distillation of
coal or cannel, or such as have been set or used for gas-making, introducing
divisional plates or diaphragms, say, between the retorts and their mouth-
pieces, and making suitable openings in the said mouth-pieces and the doors
for connection of pipes or other apparatus. When a charge of the "spent oxide"

page_text: has been placed in the retort, the lid, door, or cover luted on, and heat
applied, ammoniacal vapours, more or less contaminated with sulphur, are given
off, and this at a low temperature before the mass of the charge has been
sufficiently heated for free distillation of the sulphur. The said vapours may
be condensed in suitable apparatus with or without water or acids. As the
heat increases the sulphur vapour comes over, and is condensed in the mouth-
pieces in any cool part of the retort or in suitable cooling apparatus, from
which it flows in a liquid state into any suitable receptacle, and on solidifying
forms "rough sulphur." A heat below visible redness is sufficient for the
distillation of the sulphur. The condensed ammonia and ammoniacal salts may
be separated from sulphur by lixiviation, and purified by re-distillation from
lime in the usual way. As the distillation of the sulphur proceeds, I find it
advantageous to agitate the material in the retort by a suitable tool; using
preferably for horizontal retorts a tool so constructed that it will turn over
the material in the manner of a plough, the handle or shaft being worked
through a small orifice in the door, lid, or cover of the retort to avoid the
admission of air. By so stirring or agitating the process is shortened and fuel
saved. I also save fuel by using the waste heat from gas retorts, or any other
waste heat where such an arrangement is convenient. In using the waste
heat from gas retorts, for instance, I place the sulphur retort oven at the back
of or contiguous to the oven in which the gas retorts are set, and carry the
whole or part of the waste heat around the sulphur retorts, finally allowing it
to pass into the chimney. By the use of cooling apparatus similar in its
principle of action to that ordinarily used in the manufacture of "flowers of
of sulphur," the sulphur may be obtained from "oxides" in the form of
"flowers," or the purer portions may be formed into "roll" or "stick"
sulphur by allowing them to flow into suitable moulds. If the sulphur is the
only volatile article or product desired from the said spent materials, then the
ammoniacal and other uncondensed vapours may be passed off into the atmo-
sphere, or by a pipe or otherwise into the furnace, oven, flue, or chimney. Super-
heated steam, atmospheric air that has been passed through coke, charcoal,
or other carbonaceous matter at a high temperature, or other heated gases
may be applied for separating ammonia and sulphur from "spent oxides," by
carrying a pipe coiled or otherwise, or several pipes, into, through, over, or
under the spent materials in the distilling retorts or elsewhere. Any available
waste heat might be used to raise the temperature of the steam or other gas,
and the arrangements for condensation, herein-before pointed out, could be
retained.
Secondly, to another mode or method of extracting sulphur from similar

page_text: oxides. I accomplish this by pressure while the sulphur is in a state of fusion.
The oxides are heated and agitated in closed or partially closed vessels until
the temperature has been uniformly raised to about 250° Fahrenheit. In this.
condition it is placed in suitable straining or expressing apparatus. For
instance, it may be placed in strong bags of woollen cloth or other fabric, and,
passed between heated rollers, filtration or straining being performed in the
operation. In this process superheated steam or other heated gas may also:
be used in the same way for fusing the sulphur in the said "spent materials."
Thirdly, to another mode or method of extracting sulphur from similar.
oxides. The "spent material" is digested in hot oil, hot caustic, potash, or
turpentine, solutions of sulphur are thus obtained, which on cooling deposit
their sulphur in a solid form.
Fourthly, to extracting salts of ammonia and iron from the oxides herein-
before named, by levigating or lixiviating with water, or by drying, grinding,.
and then lixiviating with water. To the material levigated or ground, if
necessary, I add a sufficient quantity of water, preferably hot, so as to dissolve.
the salts of ammonia and iron. The oxides and other undissolved matters are
separated from the solution by subsidence, decantation, filtration, and pressure..
The said solution may be treated for obtaining ammoniacal salts in a solid
form. The residue may be treated for the extraction of sulphur according to.
either of the processes under the first, second, or third heads.
Fifthly, to the utilization of the sulphur in the said oxides by the obtain-
ment therefrom of sulphurous acid gas. I take the material, either in a damp
or dry state, and tread, ram, or otherwise compress it until it can be cut or.
broken into lumps that will bear handling without too much disintegration..
These lumps are then placed in a common grate, a furnace, or other suitable,
fire-place, and when kindled sustain their own combustion, the said fire-place
being fed as required. The sulphurous acid gas is led into the vitriol chambers;
or other apparatus in which it may be desired to use it. The burnt oxide.
drops or is raked through the bars of the fire-place, and may be applied to,
various purposes herein named. If the ammonia has not been previously
extracted from the "spent oxides," it may be separated from the sulphurous,
acid gas by cooling by a porous material, or by other suitable means or
apparatus placed in the passage, through which the sulphurous acid gas is
carried on its way to the receptacle where it is to be used.
Sixthly, to the treatment of bog iron ore and other oxides that have been
used in purifying gas for obtaining sulphates of iron and ammonia. With this.
object I beat the material without access of air, or with limited access of air
or oxygen, and cool it by wetting with water, or by any other means capable
:

page_text: of preventing the injurious action of the air on it while hot. After being
quenched or cooled, I expose it to the action of rain (or water, or otherwise
applied) and oxygen or atmospheric air, with or without the assistance of
moderate heat and agitation, until the mass acquires a degree of pastiness or
adhesiveness, or till the salts are observed to effloresce on the surface, or until
it is known by any other test to be sufficiently acted on. It is then lixiviated,
and sulphates of iron and ammonia obtained in a solid form by evaporating
the lixivium. The excess of acid, if any, in the lixivium, or in the resulting
salts, may be neutralised by the addition of iron or ammonia. Should the
'spent oxides" contain a larger proportion of sulphur than is necessary to
convert the available oxides contained in them into sulphates, then I extract
the excess of sulphur by any of the processes described under the first, second,.
or third heads, and treat the residuum for sulphates, as herein-before set forth;
or I add to the spent "oxides," previous to treating it, a quantity of oxide of
iron, or of metallic iron finely divided equivalent to the excess of sulphur, so
as to obtain a maximum quantity of such sulphates; or, I add metallic iron
in a fine state of division together with water, and quickly grind the whole into
a paste, keeping it in that state by agitation and the addition of water, if
necessary, until the desired chemical action takes place. The formation of
the sulphuret may also be effected by heating the "oxides," either after or
simultaneously with the addition of the metallic iron to a temperature that will
fuse the sulphur. The sulphuret so formed may be treated as above described.
If it is desired to increase the yield of ammoniacal salts, then I add to the
material to be lixiviated or to the lixivium ammonia, liquor of gasworks, or
ammonia in any other available form. The resulting oxides, sulphurets, and
carbonates, if any, may again be treated as above mentioned.
Seventhly. Here the object is to produce alum and sulphate of alumina, or
either of them, from "spent oxides" containing available alumina, or to which
alumina has been added. I heat the "oxides" without or with limited access
of air, and cool the heated material as described in the sulphate of iron section
(sixth); I then expose the material to the weather, or to oxygen and water,
until the desired chemical action has taken place. Instead of merely exposing
the material to the weather, or to oxygen and water, after the first heating, it
may be gently calcined or roasted in a somewhat similar manner to that
adopted with alum shale. As with alum shale, so also may these two operations
be combined to produce sulphates of iron and sulphates of alumina in one
operation. Ammonia, alum, and sulphate of alumina are obtained by lixiviating
the material treated as above. The sulphate of alumina may be converted
into potash alum, or ammonia alum, by the addition of potash or ammonia,

page_text: and these salts obtained by known means used in the manufacture of alum.
If the sulphur in the "spent oxides "is in excess, the yield of sulphate of
alumina and alum may be increased by the addition of alumina, (preferably
calcined,) and metallic iron or oxide of iron finely divided. Or alumina alone,
(preferably calcined,) may be added to and heated. with the material prepared
for lixiviation.
Eighthly, to the production of carbonate of soda and other compounds of
sodium from the "oxides," throughout referred to. By substituting common
salt for alumina in the above (seventh) process, I form sulphate of soda,
sulphuret of sodium, and other sodium compounds, which may be used for the
manufacture of carbonate of soda and other purposes to which the said com-
pounds of sodium are applicable. Muriate of iron and oxide of iron are
products of this operation. Such muriate may be converted into oxide and
chloride of calcium or muriate of ammonia by mixture with lime or ammonia,.
and the chloride of calcium and muriate of ammonia may be removed from
the oxide and other insoluble matter by lixiviation..
Ninthly, to the application of the residual oxides from the foregoing processes
to the manufacture of pigments, with or without previous washing.. I heat the
said residual oxides with access of air, preferably in an oven or reverberatory
furnace, until the combustible parts are sufficiently burnt off, and subject them
to grinding, sifting, elutriation, or other known means. The residue from the
sulphurous acid process (fifth), however, may be used as a pigment without
the burning herein described. The water used for washing the said oxides
may be evaporated to obtain salts of iron and other substances.
Tenthly, this relates to the treatment and application of the residual oxides
from any or all of the processes before described to render them suitable for
repeated use in the purification of gas. The residuum from which the sulphur
and other vapour has been distilled or sublimed under the first head is removed
from the retort into water, or is immediately quenched with water. The
residue from which the sulphur has been expressed, as described under the
second head, may be reduced to powder damped, and then used with or without
washing or further preparation. The residue from the third and fourth, the burnt
oxide from the fifth, and the residue from the sixth, seventh, eighth, and from
the ninth heads (if any, from the latter), may also be quenched with water, with
or without extra burning or washing, and applied for the same purpose. In
all these cases the treated materials may be advantageously added to or mixed
with oxides that have been partially "spent," so as to sustain their purifying.
power. I prefer, however, where it is convenient, to pass the treated oxides
through a bolting machine or fine sieve before using them for purification.

page_text: Eleventhly, under this head I utilize the ammoniacal vapours given off by
oxides while undergoing the process of revivification, by passing a gentle
current of air through the reviving materials, and afterwards passing this
charged air through any porous material that will absorb the ammonia. This
may be effected in a simple and inexpensive manner by placing the "fouled
oxides," as they are removed from the purifiers, in shallow bins or chambers
of brick or other suitable material provided with false floors, bottoms, or tiers,
say iron or wooden grids or perforated plates or tiles, and connecting the same
to a chimney draught or suitable machine, regulated to pass just sufficient air
to renovate or revive the materials without injurious heat. From the reviving
bins or chambers the air is carried by the same means through another bin, or
successively through two, three, or more bins of like construction, but provided
in addition with covers. These latter contain the porous absorbent. If the
said absorbent is used in the same chamber as the "fouled oxides," on separate
trays, or in layers, cocoa-nut matting or other open fabric may be employed
to prevent the materials from mixing one with another. As soon as the
absorbent has become sufficiently charged with ammonia, fresh charges are put
in, the "fouled" material being treated for ammonia or used as a manure.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Cleland in the Great Seal Patent Office on the
14th July 1862.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
CLELAND, of 39, St. George's Hill, Everton, Liverpool, in the County of
Lancaster, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifteenth day of January, in the year of our
Lord One thousand eight hundred and sixty-two, in the twenty-fifth year of
Her reign, did, for Herself, Her heirs and successors, give and grant unto
me, the said William Cleland, Her special licence that I, the said William
Cleland, my executors, administrators, and assigns, or such others as I, the
said William Cleland, my executors, administrators, and assigns, should at
any time agree with, and no others, from time to time and at all times there-
after 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 "IMPROVEMENTS IN
TREATING AND UTILIZING CERTAIN MATERIALS USED AND PRODUCTS OBTAINED IN THE

page_text: MANUFACTURE OF GAS, AND IN APPARATUS CONNECTED WITH THE SAID TREATMENT,"
upon the condition (amongst others): that I, the said William Cleland,. my ex-
ecutors or administrators, by an instrument in writing under my,.or their, or one
of their hands and seals, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be performed,
and cause the same to be filed in the Great Seal Patent Office within six
calendar months next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said William Cleland, do hereby declare
the nature of my said Invention, and in what manner the same is to be
performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Sheet of explanatory Drawings
accompanying this (that is to say):
-
My improvements relate, firstly, to the extraction of ammonia and sulphur
from bog iron ore and other oxides of iron that have been used for purifying
gas from these substanees. I effect this by distillation or sublimation, and
in general find it most convenient to employ retorts somewhat similar to those
used in the distillation of coal or cannel, or such as have been set or used
for gas-making from coal or cannel, introducing divisional plates or dia-
phragms, say, between the retorts and their mouth-pieces, and making suitable
openings in the said mouth-pieces and the doors for connection of pipes
or other apparatus to carry off the volatile and other distilled products.
When a charge of the "spent oxide," has been placed in the retort, the
lid, door, or cover luted on, and heat applied, ammoniacal vapours, more
or less contaminated with sulphur, are given off, if the material contains
ammonia, and this at a low temperature, before the mass of the charge
has been sufficiently heated for free distillation. of the sulphur. The said
vapours may be condensed in suitable apparatus with or without water or
acids. As the heat increases the sulphur vapour comes over, still. accompanied
by ammoniacal vapour if ammonia is present, and is condensed. in the mouth-
piece in any cool part of the retort, or in suitable cooling apparatus, from
which it flows in a liquid state into any suitable receptacle, and on solidifying
forms "rough sulphur." The ammoniacal and watery vapours requiring
a lower temperature for their condensation pass to that part of the apparatus.
intended for their reception. A heat below visible redness is sufficient for
the distillation of the sulphur, but a. dull red heat is in general the most advan-*
tageous, although higher heats may be used if the power of condensation is
sufficient to prevent the escape of gaseous free sulphur. The condensed.
ammonia and ammoniacal salts may be separated from sulphur by lixiviation.
and purified by re-distillation from lime, the distillate being received into

page_text: sulphuric acid in the usual way. As the distillation of the sulphur proceeds
I find it advantageous to agitate the material in the retort by a suitable tool,
using preferably for horizontal retorts a tool 'so constructed that it will turn
over the material in the manner of a plough, the handle or shaft being worked
through a small orifice in the door, lid, or cover of the retort, to avoid the
admission of air. By so stirring or agitating, and thus bringing a larger
proportion of the charge in contact with the interior surface of the retort,
the process is shortened and fuel saved. I also save fuel by using the waste
heat from gas retorts or any other waste heat where such an arrangement is
convenient. In using the waste heat from gas retorts, for instance, I place
the sulphur retort oven or ovens at the back of or contiguous to, or in the
vicinity of the ovens in which the gas retorts are set, and carry the whole
or part of the waste heat beneath or around the sulphur retorts, regulating
the quantity by dampers, and finally allowing it to pass into the chimney. By
the use of cooling apparatus similar in its principle of action to that ordinarily
used in the manufacture of "flowers of sulphur," the sulphur may be obtained
from "spent oxides," in the form of "flowers," or the purer portions may be
formed into "roll" or "stick sulphur," by allowing them to flow into suitable
moulds, the ammonia, if any, having been previously extracted by the mode
or modes described under the herein-after recited fourth head.
I am aware that other parties state that sulphur can be extracted from
"spent oxides" of iron by distillation or sublimation, but they have done
so under the erroneous impression that the process is applicable to all such
oxides. I wish here to point out, for the first time, that the process of dis-
tillation or sublimation is subject to serious limitations and exceptions, and
that the unqualified assertion, that "spent oxides of iron," will thus yield free
sulphur, is fallacious. When these oxides are heated in closed vessels there
is produced in the said vessels a chemical compound of sulphur and iron,
which I call "sulphide of iron," (a term which I use without vouching for
its scientific accuracy,) and not, as heretofore imagined, a mere mechanical
mixture of oxide of iron, or carbide of iron, with carbonaceous matter and
sulphur. Unless, therefore, a "spent oxide," contains more sulphur than
is necessary for the production of this so-called "sulphide of iron," it yields.
no free sulphur at any degree of heat that is practically applicable. Now
there are many "spent oxides," containing a large per-centage of free sulphur,
which yet contain no more than is necessary to the production of the "sul-
phides," and I have found the process as applied to them a failure. I may
mention, for instance, hard oxides that are not very finely divided, and oxides
prepared from iron borings exposed to air and moisture. It is only from

page_text: oxides, therefore, comparatively. rich in sulphur, that I extract it by distillation
or sublimation. A simple method of ascertaining whether a "spent oxide "
may be advantageously treated for sulphur under this head, is to heat a known
weight, say half a pound, in a small porcelain retort and weigh the sulphur,
if any, that comes over.
Clay retorts, on account of their porosity and liability to crack, are not
in general to be recommended for this process unless low heats are used.
Cast-iron retorts are preferable for the higher heats, and wrought iron or
a combination of wrought and cast iron gas retorts may be profitably
applied to this purpose in the summer months when they are not required
for gas making. A moderate coating of carbon internally is no objection, but
rather an advantage, particularly if wrought iron is employed, as it protects
the iron from the action of the sulphur, and the retorts may be restored to
their original use with little alteration.
Fig. 1 on the accompanying Sheet of Drawings represents a vertical and
longitudinal section of a gas retort and other apparatus well adapted and
arranged for carrying this process into effect, part of the setting of the
retort being also shewn. Here the retort a has a cast-iron bottom, and. the
sides and top are formed of wrought iron, b, the mouth-piece, also of cast iron.
The ordinary ascention pipe is removed, and the socket on the mouthpiece
receives in its place a pipe c, for conveyance of the ammoniacal and other
vapours into the fixing or condensing vessel or chamber d, herein-after.
described; e, a moveable plate or diaphragm, let into the joint of the mouth-
piece and fixed by a clay or other luting to prevent the liquid sulphur from
flowing back into or amongst the oxide. The mouth-piece b, kept cool by a jet
of water, if necessary, acts as a sulphur condenser, and the liquid sulphur flows
through the syphon f, or through an orifice in the lid g or mouth-piece, which
orifice may be closed at pleasure, into any convenient receptacle such as the
sheet-iron tray h. If the uncondensed vapours are passed from the retort
into the arch or flue, it is desirable that the exit pipe be gradually closed.
as the operation proceeds so that gaseous sulphur may not escape. There.
is always a loss of sulphur in this way, especially with damp oxides, unless:
the retort is allowed to cool somewhat before receiving a fresh charge.
When apparatus is specially constructed for the treatment of "spent oxides.
of iron," I prefer a vertical or inclined retort, capable of being charged at
top and drawn at bottom, and in which the. evolution of both sulphur and.
ammonia may go on simultaneously and continuously. Fig. 2 shews an:
arrangement of apparatus for this purpose in vertical section; and Fig. 3:

page_text: shews a horizontal section of the retort at Z, Z. The vertical retort i, I
propose heating by an ascending spiral flue, provided with regulating dampers at
the three points marked respectively j, k, and l, where the said flue branches
into the main flue or chimney. Above the point 7 there is just sufficient heat
to dry or partially dry the material, but between the points land- the heat is
increased to a temperature that will drive off part of the ammoniacal vapours
through the pipe m into the fixing or condensing chamber herein-after
described; and between the points k and the temperature is high enough to
drive off the sulphur by way of the outlet pipe n, and should any ammoniacal
vapours pass by this outlet, they will pass up the pipe into the condensing
chamber; p represents diagonal plates or vanes. introduced into the retort,
and resting on snugs, or otherwise attached therein, to give the material an
alternate travel from the centre to the circumference, so as to bring it
successively into the vicinity of the greatest heat; q, a slide or shoot for
drawing off the burnt or exhausted material. The sulphur vapour passes
into the chamber r, where it is condensed, and flows out by the syphon t, or
through an orifice in the lid u, which said orifice may be closed by a moveable
plug. Should a stoppage in the syphon t take place, then the diaphragm or
plate v prevents the sulphur from returning into the retort. The chamber or
vessel for condensing the ammoniacal vapours, or in which the ammonia is
absorbed, is the same in both Figs. 1 and 2, and like letters of reference
denote the same parts in both views.
Without confining myself to any particular mode or modes of fixing the
ammonia, I may state that I prefer the following:-The vapours are led into
the vessels d by the pipes c, Fig. 1, and m, o, Fig. 2, such vessels being pro-
vided with tiers of grids or perforated plates w, as in dry lime purifiers,
charged with the crude sulphate of iron material, (obtained as described under
the sixth head, herein-after mentioned,) which it is best to have in rather fine
powder, and somewhat damp. As the uncondensed gases pass through this
material, the animonia is more or less perfectly arrested and fixed, and the
sulphate of iron decomposed. When it is found, on agitating a sample of the
material with water, and adding caustic ammonia to the clear solution, or by
any other test, that it no longer contains soluble salts of iron, the material
may be discharged and a fresh supply substituted. On lixiviating the spent
material with water, and evaporating the solution, crystalline sulphate and
sulphite of ammonia are obtained. When the crude sulphate of iron is first
used for this purpose, I prefer mixing it with sawdust or other porous
material to increase its porosity. After the first charge is spent, however,

page_text: mixture with foreign matter is no longer necessary, as the fresh sulphate of
iron may be mixed with a portion of the spent material, which answers the
same end as the sawdust.
Another mode of fixing the ammonia consists in placing sawdust moistened
with water on one or more of the lower grids or perforated plates, and on the
upper ones sulphate of iron or sawdust moistened with weak sulphuric acid.
The more fixed ammoniacal compounds, such as sulphate and sulphite, will be
arrested by the moist sawdust, while the ammonia of the more volatile
products, such as the hydro-sulphate of ammonia, will be fixed by the sulphate
of iron or sulphuric acid. The sulphate of ammonia obtained by either of
these modes, and contained in the spent sulphate of iron material, may be
extracted by lixiviation. In effecting this I run a given quantity of water,
either cold or hot, through successive portions of the material, so as to obtain
a saturated, or at least a strong solution of sulphate of ammonia, and thus
save subsequent evaporation. The lixiviated residue, being partially dried and
exposed to the air, becomes again fit for purifying gas, as mentioned herein-
after under the tenth head. The condensing or fixing vessels used for either
of these modes, or for any other convenient method, may be open at the top
to allow the uncondensed gases to pass off into the air, or they may be closed,
and have an outlet waste pipe carried into the chimney, or elsewhere. And,
in any mode, those grids or perforated plates with the charges thereon, forming
the upper tiers in the vessels, may be used as the lower tiers when a fresh
charge is supplied to the upper ones.
Superheated steam, atmospheric air that has been passed through coke,
charcoal, or other carbonaceous matter at a high temperature, or other
suitable heated gases, may be applied for separating ammonia and sulphur
from "spent oxides," by carrying a pipe, coiled or otherwise, or several pipes,
into, through, over, or under the spent materials in the distilling retorts, or
elsewhere. Any available waste heat might be used to raise the temperature
of the steam or other gas, and the arrangements for condensation of the
ammonia and sulphur, and collection or extraction of the same, herein-before
pointed out, could be retained; but in this system I would have it understood
that a larger cooling surface in the condenser is desirable.
Secondly, to another mode or method of extracting sulphur from such
oxides of iron. I accomplish this by pressure while the sulphur is in a state
of fusion. The oxides are beated and agitated in a closed or partially closed
vessel, until the temperature has been uniformly raised to about 250°
Fahrenheit. To obtain this temperature I use a cylindrical vessel a', shewn
in longitudinal section by Fig. 4, on the accompanying Sheet of Drawings,

page_text: fixed in an inclined position, and heated by a flue surrounding the same, or in
any other convenient way. The "spent oxide" is introduced by the hopper b',
and is carried onwards to the outlet c', closed by the door d', by a spindle e
resting on bearings in both ends of the cylinder. This spindle is fitted with
arms or vanes ex, set at an angle, or otherwise twisted, so that when the
spindle is turned by hand or other power, they not only agitate the material
being operated on, but they act as a screw, by carrying it onwards towards
the shoot or outlet c. The angle at which the cylinder is set and the speed
of the spindle and arms should be so adjusted, that when the material reaches
the lower end the sulphur will be thoroughly fused. In this condition, that
is, when fused, it is placed in suitable straining or expressing apparatus; for
instance, it may be placed in strong bags of woollen cloth or other fabric,
enclosed and strengthened, if necessary, by nets of rope or strong cord, and
passed between heated rollers, kept hot by jets of burning gas inside the same,
or by other means, filtration or straining being performed in the operation.
Or the bags may be placed in a heated cylinder with a perforated bottom and
sides, and pressure applied by a piston, perforated or solid.
The expressing apparatus which I prefer, however, is shewn on the accom-
panying Sheet of Drawings, where Fig. 5 is a horizontal section of so much
of the apparatus as is necessary for a full understanding of the same, and
Fig. 6 is an enlarged view of the disconnecting and straining part of the same.
Like letters denote the same parts in both views. f¹ represents the cylinder,
which is fitted and fastened in a slanting position to any strong framework;
g, the piston, to which water, steam, or other power is applied, through the
piston rod h³, to move it in either direction; ', the cylindrical frame of the
straining apparatus, which abuts or closes against the cylinder, and is made
tight by packing j¹; k, the rods on which this said straining apparatus slides,
the power moving it being applied through the rod 1. The strainer m¹ con-
sists of a sheet or sheets of strong and close fabric, such as doeskin or
moleskin, strengthened and protected on one or both sides by wire gauze, and
at the back by the perforated disc n', and kept in position by the recessed
ring o. The modus operandi of this expressing apparatus is as follows:-A
quantity of the heated material containing the fused sulphur is allowed to drop
from the outlet c', by opening the door d¹ (see Fig. 4,) into the hopper p',
shewn by dotted lines. The piston is then set in motion, and the material is
forced down upon the strainer m³, through the pores of which, as well as
through the perforated plate n', the liquid sulphur is pressed into the interior
of the frame i¹, from whence it flows out by the aperture q¹. As soon as the
expression of the sulphur in each charge is effected, the straining apparatus

page_text: is drawn back to a convenient distance, and the compressed material is ejected
at the lower end of the cylinder by further movement of the piston g¹. The
piston and expressing apparatus are then returned to their original position,
as shewn in the Drawings, and the apparatus is ready for another supply. I
apply the same degree of heat to the fusing and expressing apparatuses, both.
of which I enclose as much as possible by suitable hoods, chambers, or brick-
work, to prevent loss of heat. I have found the most convenient heat to be.
from 240° to 250° Fahrenheit, and I would recommend that a temperature of
not less than 230° nor more than 280° should be used, as fused sulphur is in
a very liquid condition within that range of temperature.
There are certain carbonaceous compounds derived from gas during puri-
fication, and contained in the "spent oxides" operated on, which are not
easily separated from the sulphur obtained by fusion and pressure, and which
give it a dark colour and objectionable odour. These impurities may be:
extracted from the sulphur by simple distillation or sublimation, and to prevent
the sulphur from boiling over in an impure frothy condition during the:
operation a deep retort relatively capacious may be employed. Part of the
impurities pass off as vapour, and the sulphur follows. There is left in the
retort a quantity of finely divided carbon, which I use as a pigment. In this
process superheated steam or other heated gas may also be used in the same
way, as described under the first head, for fusing the sulphur in the said
"spent materials." It is scarcely necessary to observe that this process
cannot be recommended for oxides containing a small per-centage of free
sulphur.
Thirdly, to another mode or method of extracting -sulphur from similar
oxides containing free sulphur. The spent material is digested in hot oil, hot
caustic potash, or turpentine. Solutions of sulphur are thus obtained, which,.
on cooling, deposit their sulphur in a solid form. The oils suitable for this
purpose are the fixed oils, those generally known as paraffine, rock, and earth
oils, and other like hydrocarbons. Whether oil, potash, or turpentine is used,
the crystalline sulphur is to be separated from the mother liquor by agitation, "
subsidence, and decantation. The crystals are then thrown on a filter or
cullender to drain, or they are strained by pressure in any convenient way.
The still moist sulphur is then to be heated and fused, preferably heated
to a temperature between 230° and 280° Fahrenheit, when the moisture
will either pass off in vapour, or appear as a liquid on the surface of
the sulphur, from which it may easily be separated when the latter has
solidified.
Fourthly, to extracting salts of ammonia and iron from the oxides herein-

page_text: before named, which contain these substances, by levigating or lixiviating with
water, or by drying, grinding, and then lixiviating with water. To the material
levigated or ground, if necessary, I add a sufficient quantity of water, pre-
ferably hot, so as to dissolve the salts of ammonia and iron. The oxides,
sulphur, and other undissolved matters are separated from the solution by
subsidence and decantation, filtration and pressure, or either of them, or by
any other convenient mode. The said solution may be treated for obtaining
ammoniacal salts in a solid form in the usual way. Gas liquor, or ammonia
in any other available form, may be added to the solution, or to the dried and
ground oxides, to decompose any soluble salts of iron which they may contain ;
if, on the other hand, the material is alkaline, it may be neutralized by the
addition of a mineral acid, say, sulphuric acid. The insoluble residue may be
treated for the extraction of sulphur, according to either of the processes
under the first, second, or third heads.
Fifthly, to the utilization of the sulphur in the said oxides, by the obtain-
ment therefrom of sulphurous acid gas. I take the material either in a damp
or dry state, but prefer to have it slightly wet, and tread, ram, or otherwise
compress it until it can be cut or broken into lumps that will bear handling
without too much disintegration. These lumps are then placed in a common
grate, a furnace, or other suitable fire-place, and when kindled sustain their
own combustion, the said fire being fed as required. The sulphurous acid gas
is led into the vitriol chambers or other apparatus in which it may be desired
to use it. The burnt oxide drops or is raked through between the bars of
the fire-place, and may be applied to various purposes herein named. The
ammonia, if the material contains ammonia, may be previously washed out of
the "spent oxides "according to the process described under the fourth head.
If the ammonia has not been previously extracted from the "spent oxides," it
may be separated from the sulphurous acid gas by cooling, by a porous
material, or by other suitable means or apparatus placed in the passage through
which the sulphurous acid gas is carried on its way- to the receptacle where it
is to be used. This combustion process is specially applicable to those "spent
oxides" which contain a considerable quantity of sulphur. But if the sulphur
has been previously extracted by distillation or sublimation, or if it has been
fixed by heating in closed vessels, as described herein-after under the sixth
head, then the residue from the retorts, which is a sulphide of iron, may have
its sulphur burnt off by any convenient means, and the sulphurous acid
applied to the manufacture of vitriol or other purposes, according to known
methods as practised with iron pyrites.
Sixthly, to the treatment of bog iron ore and other oxides of iron that have

page_text: been used in purifying gas for obtaining sulphates of iron and ammonia.
With this object I heat the material without access of air, or with limited
access of air or oxygen; a temperature of about 600° Fahrenheit answers:
well, but I prefer a dull red heat, and much higher heats may be used. After
heating I cool it by wetting with water, or by any other means capable of
preventing the injurious action of the air on it while hot. After being.
quenched or partially cooled I expose it to the action of rain (or water other-
wise applied) and oxygen or atmospheric air, with or without the assistance"
of moderate heat and agitation, until the mass acquires a degree of pastiness:
or adhesiveness, or till the salts are observed to effloresce on the surface, or
until it is known by any other test to be sufficiently acted on. It is then
lixiviated, and sulphates of iron and ammonia (should the spent oxide contain
ammonia) obtained in a solid form by evaporating the lixivium. The pro-
portion of sulphate of ammonia thus obtained is influenced by the degree of
heat to which the "spent oxide" has been subjected, low heats being the
most favourable; but the ammonia may be previously washed out, as described
under the fourth head. The excess of acid, if any, in the lixivium, or in the
resulting salts, may be neutralized by the addition of iron or ammonia for the
production of copperas or sulphate of ammonia. Should the "spent oxides"
contain a larger proportion of sulphur than is necessary to convert the available,
oxides contained in them into sulphates, then I extract the excess of sulphur:
by any of the processes described under the first, second, third, or fifth heads,,
preferably without superheated steam or other beated gases, and treat the
remainder for sulphates, as herein-before set forth; or I add to the "spent.
oxide," previous to treating it, a quantity of oxide of iron, preferably hydrated.
oxide, or of metallic iron finely divided, equivalent in some measure to the.
excess of sulphur, (which excess may be readily estimated with tolerable cor-
rectness by subjecting an average sample of the material to the distillatory.
process in a small porcelain retort,) so as to obtain a maximum quantity of
such sulphates; or I add metallic iron in a fine state of division together with:
water, and quickly grind the whole into a paste, keeping it in that state by
agitation, and the addition of water, if necessary, or allowing it to remain at.
rest covered with water, or otherwise excluded from the air, until the desired.
chemical action takes place, that is, until the iron and the excess of sulphur
have combined to form sulphide, which may be known by any suitable,
chemical test. It may be ascertained, for instance, by drying a portion of the.
mixture and digesting it in rectified naptha, and evaporating the liquor, which
will yield sulphur, if the sulphur in the mixture is still uncombined. The
formation of the sulphuret or sulphide may also be effected by heating the

page_text: oxides either after or simultaneously with the addition of the metallic iron,
preferably to a temperature of from 250° to 600° degrees Fahrenheit. The
sulphuret or sulphide of iron formed by either of these last two modes may
be treated as above described, that is, for the production of sulphates of iron
by heat, spontaneous or applied, preferably a heat sufficient to ignite the
sulphide. In the case of the sulphides produced by these two modes it is
advisable that the ignition should be allowed to go on moderately instead of
being quenched with water, as directed for the sulphides formed from " spent
oxides" heated in closed vessels. Those oxides of iron which I have most
successfully treated under this head are the unmixed bydrated peroxides, both
natural and artificial, and the unmixed magnetic oxide or magnetic "carbide
of iron," and those quantities which were in the finest state of division,
when originally used for the purification of gas, gave the best results. By
"unmixed oxides" I mean those which are free from or contain the smallest
proportion of "porous material" or earthy ingredients. When I use oxide of
iron, therefore, with a view to its conversion into sulphates, I prefer the most
finely divided oxides with the smallest proportion of or free from "porous
material" or other matters having no affinity for sulphuretted hydrogen.
Oxides that have been mixed with any considerable proportion of caustic lime,
or lime in any such combination that it will become caustic at a red heat, are
not well suited to form sulphates of iron, as these salts are decomposed by
caustic lime and other alkaline substances.
To produce sulphates of iron in quantity from "spent oxides" of iron, it is
only necessary to apply heat so as to kindle the sulphur and cause it to burn
slowly away, without too much disturbance, and at a moderate heat. Hence
the process may be carried out by simply slowly burning the sulphides and
"spent oxides," or allowing the spontaneous combustion of either of them to
go. on, preferably in masses or covered heaps, and lixiviating the residue
according to well-known modes practised in the manufacture of sulphates of
iron and alumina from alum shale. There is generally, however, under this
treatment a loss of sulphur, too much of it being given off as sulphurous acid
gas, and too much of the iron being left in the state of free peroxide. The
more the air is excluded in the first heating of the material the greater the
produce of sulphate of iron will be. I therefore prefer to exclude the air
entirely, as I have pointed out above, by heating the "spent oxide" in a retort
or other closed vessel, and quenching the resulting sulphides with water as
withdrawn from the heating vessel, or allowing them to cool before being
withdrawn. To produce sulphates of iron to some extent from the above-
named sulphides, it is only necessary to roast or burn them with a moderate

page_text: heat in the air without too much disturbance, or allow their sulphur to burn
slowly off by exposure to air while still hot, without quenching. But in
this case also there is generally an unnecessary production of sulphurous acid
gas and peroxide of iron, and a corresponding deduction from the sulphate of
5-iron desired.
The excess of sulphur in raw "spent oxides" may also be burnt off in any
convenient way previous to applying such oxides to the production of sulphide
or sulphate of iron.
The process which I prefer as the most advantageous consists in quenching
the sulphides as they are drawn from the retort with water, and exposing the
mass to the air while damp. I lay it in this condition in level heaps or beds,
say about two feet deep, where, in general, it spontaneously heats, and
frequently ignites from the rapid oxidation of the sulphide. This ignition
ought to be immediately checked as often as it occurs, by slightly watering
the material, and turning it over if necessary until chemical action has been
so moderated that there is no further risk of ignition. When all heat has
disappeared, and when, after turning over and damping a heap of the material
slightly and uniformly, there is no renewal of heat, the process of conversion
into sulphate may in most cases be considered to be practically complete. The
progress and completion of the conversion may be known by lixiviating from
time to time a given weight of the material in water so as to ascertain the
proportion of insoluble matter, which will be found to diminish until the
oxidation of the sulphide has ceased. The use of applied heat for the pro-
duction of the sulphate is advisable when the spontaneous production does
not proceed satisfactorily.
If it is desired to increase the yield of ammoniacal salts, then I add to the
material to be lixiviated, or to the lixivium, ammonia liquor of gasworks, or
ammonia in any other available form. The ammonia or ammoniacal com-
pounds evolved while heating the "spent oxides" in closed vessels to produce.
sulphides may be utilized as directed under the first head.
I effect the saturation and decomposition of the sulphate of iron material by
ammonia in various ways. I lay it on grids or perforated trays in the ordinary
dry lime purifiers in a pulverized and slightly damp condition, where it effectually
frees the gas from ammonia. It may either be used in a separate purifier or
set of purifiers, or in separate tiers in the same vessels with the ordinary puri-
fying material. In the latter case I lay cocoa-nut matting, coarse sacking, or
other open fabric, under or over it to prevent admixture. I also use it for
absorbing the ammonia given off from "oxides" undergoing revivification or
ventilation, as described under the eleventh head herein-after. I likewise use

page_text: it for fixing the ammonia driven off by heat from oxides that have been used to
purify gas, as stated under the first, fifth, and under this sixth head.
I
If ammonia liquor of gasworks is used, I prefer to proceed as follows:-I
drive off the volatile ammonia and ammoniacal compounds in the said liquor
by boiling, as practised in the ordinary manufacture of sulphate of ammonia;
but instead of receiving the vapours or condensed steam into sulphuric acid,
pass the steam into the sulphates of iron, whereby they are decomposed,
and sulphate of ammonia produced. I first pulverize the sulphate of iron, and
generally find it most convenient to mix it with damp sawdust, say from one-
half to one-third of its bulk, or, which is better, with a damp oxide of iron in
a state suitable for purifying gas. Either of these mixtures may be placed in
a vessel or chamber shewn by Fig. 7 in the accompanying Sheet of Drawings
in vertical section. a represents the body of the vessel; 62, the lid or cover
for the same; c², ledges for supporting the grids or perforated plates d²;
e², the inlet pipe; f2, the outlet pipe; 92, ledges all round, of greater width
than those shewn by c², for supporting or carrying the grids. The steam from
the heated or boiling gas liquor is introduced by the pipe e², from which it
passes through the material on the grids dwhere it is deprived of its
ammonia, and then passes off by the pipe f2. It is desirable to avoid any
great condensation of steam in the purifier or absorbing vessel, as too much
water makes the material soft and pasty, less permeable to the gases, and
difficult to deal with afterwards. I guard against too much condensation,
should it occur, by surrounding the purifier with some non-conducting sub-
stance, or by slightly superheating the steam as it leaves the boiler, but many
other expedients may be used. As the process goes on, the material generally
contracts, and, parting from the sides of the vessel, would leave a free passage
for the steam in that direction, were it not barred or prevented by the pro-
jecting ledges g². The oxide of iron, besides promoting porosity, will take up
any sulphuretted hydrogen which might otherwise be passed off through the
outlet finto the chimney, or elsewhere, and such absorption would allow
When the
the outlet f and the cover or lid to be dispensed with.
steam, or a drop of water condensed from it, reddens turmeric paper, the vessel
may be discharged, and the upper part of the charge returned to the purifying
vessel to form the lower part of a fresh charge of absorbing material. This
returning of the material may be avoided, however, and the operation made
continuous, by using a set of purifiers connected by a central change valve, as
in the purification of coal gas. The sulphate of ammonia contained in the
spent sulphate of iron material, produced according to any of the foregoing
modes, is now to be extracted by lixiviation, and the oxide of iron

page_text: recovered for the purification of gas, as set forth in the process of utilizing the
ammonia under the first head. In evaporating the solution the sulphate of
ammonia, if any is present, will be more or less converted into sulphate. The
resulting oxides, sulphurets or sulphides, and carbonates, if any, may again be
treated as above described, that is, after being again used for purifying gas.
Seventhly, here the object is to produce alum and sulphate of alumina, or
either of them, from "spent oxides" containing available alumina, or to
which alumina has been added either before or after they have been used for
the purification of gas. I heat the "oxides" without or with limited access of
air, and cool the heated material as described in the sulphate of iron, section
(sixth). I then expose the material to the weather, or to oxygen and
water, preferably with the assistance of heat, until the desired chemical
action has taken place. Instead of merely exposing the material to the
weather, or to oxygen and water, after the first heating, it may be gently
calcined or roasted in a somewhat similar manner to that adopted with alum
shale. As with alum shale also, these two operations may be combined to
produce sulphate of iron and sulphate of alumina in one operation. Ammonia
alum (if the heat used has not been so high as to expel the ammonia), sulphate
of alumina, and generally sulphate of iron, are obtained by lixiviating the
material treated as above. The sulphate of alumina may be converted
into potash alum or ammonia alum by the addition of sulphate of potash,
chloride of potassium, or sulphate of ammonia, in the usual way, and these
salts obtained by known means used in the manufacture of alum. If the
sulphur in the "spent oxides" is in excess, and it is desired to utilize that
excess, it may be removed as pointed out under the sixth head, or the yield
of sulphate of alumina and alum may be increased by the addition of
alumina (preferably calcined) and metallic iron, or oxide of iron, finely,
divided; or alumina alone (preferably calcined) may be added to and heated
with the material prepared for lixiviation, that is, the sulphate of iron material,
or it may be added to the sulphide of iron or to the raw "spent oxide."
The process of manufacturing sulphate of alumina and alum from oxides of
iron that have been used to purify gas from sulphur, and which contain avail-
able alumina, or to which alumina has been added, being substantially the same
as that of the manufacture of these salts from the mineral, well known under
the names of alum shale, alum schist, and alum slate, does not call for a
lengthened description here. The sulphate of alumina may either be made
from the sulphides of iron produced by heating the oxides of iron in closed
vessels or chambers (preferably those sulphides formed at or under a dull red
heat), as described under the last (sixth) head, or from the crude sulphates

page_text: of iron of the same (sixth) head, taken from the oxidizing heaps, or from the
used oxides in their raw or original condition, with or without the previous
extraction of the ammonia. The chief differences between the manufacture
of alum from the substances just named and from alum shale arise from the
frequent deficiency of alumina in those substances, which necessitates the
addition of clay or other aluminous matter; and also, from their pulverized
condition, which renders it advisable to adopt certain modifications in the
node of calcining. Those sulphides of iron containing alumina, which
oxidize rapidly into sulphate of iron in the presence of air, and in mass heat
spontaneously, especially if the heat rises to ignition, produce sulphate of
alumina without further heating; but if the proportion of alumina or other
inert matter is large, or if, from any other cause, oxidation into sulphates
proceeds too slowly, then it is desirable that they should undergo a gentle
calcination. The material being generally in a loose or pulverized state, is
apt to choke the fires if calcined exactly in the manner of alum shale. To
prevent this, vizt., the choking of the fires, it may be compressed with or
without the addition of water, then broken into convenient pieces, and calcined
either in the ordinary way, or in kilns such as are used for calcining limestone.
When clay or other aluminous material has to be added to supply alumina,
the mixture may be effected in a mill with edge runners, or in a pug mill, and
the plastic mass dried, broken up, and calcined; or the clay may be first
either dried or calcined, then mixed by passing through suitable skreens, and
the mixture damped and compressed previous to calcining. If the crude
sulphate of iron material is used, and requires calcination and the addition of
alumina, the mixture may be carried out as recommended for the sulphides,
although I prefer to calcine the aluminous material previous to mixing.
When raw "spent oxides" are used for the production of sulphate of alumina,
the mixture of alumina, if necessary, may be made, and the mixture calcined
as directed for the sulphides of iron, but in this case it is prudent to raise the
heat more slowly, so as to allow sufficient time for oxidation and avoid
unnecesary loss of sulphur. The sulphate of alumina having been formed by
any of the above modes, the material is to be lixiviated with water, whereby
a solution of sulphate of alumina, generally mixed with sulphate of iron, is
obtained. Any excess of acid existing in this solution may be neutralized by
metallic iron, and the liquor then treated for alum and copperas; all these
steps, however, being essentially the same as in the well-known manufacture
of alum from alum shale, need not now be detailed.
Eighthly, to the production of carbonate of soda and other compounds of
sodium from the "oxides," throughout referred to. By substituting common

page_text: salt for alumina, in the above (seventh) process, I form sulphate of soda,
sulphuret of sodium, and other sodium compounds, which may be used for the
inanufacture of carbonate of soda, and for other purposes to which the said
compounds of sodium are applicable: Muriate of iron and oxide of iron are
products of this operation; such muriate of iron, when permanent, may be
converted into oxide of iron and chloride of calcium, or muriate of ammonia,
by mixture with lime or ammonia, and the chloride of calcium and muriate of
ammonia may be recovered from the oxides and other insoluble matter by
lixiviation, and the resulting oxide used for purifying gas. If desired, part of
the sulphur may be removed from the "spent oxides" (tas pointed out under
the sixth bead) previous to treating them for sulphate of soda. It is a dis-
advantage to have lime mixed with the "oxides" to be treated under this head.
I produce sulphate of soda by heating together, in presence of air, the raw
"spent oxides" and common salt, the sulphide of iron material and common
salt, or the sulphate of iron and common salt. In any case a very intimate
mixture of the salt and the sulphur compound is desirable. A reverberatory
furnace may be used for heating the mixture.
When either raw oxide or the sulphide of iron is used, I prefer grinding
these substances, when mixed with the common salt, into a paste with water,
beginning the heating process at a comparatively low temperature, to allow
time for oxidation, raising the heat gradually, and frequently turning over or
stirring the mixture while being heated. The crade sulphate of iron may be
mixed with the salt either in its natural condition or wet, although it is
advantageous. to damp the mixture and allow it to remain in a heap for some
time before heating it. Another mode is to dissolve out the sulphates of iron
with the smallest practicable quantity of hot water, and having thus obtained
a concentrated solution, or having afterwards evaporated the solution to
dryness, the sulphates are to be mixed with the common salt and heat applied.
The sulphate of iron and common salt may also be mixed in solution, and the
sulphate of soda obtained in a crystalline state by cooling the mixture, which
leaves muriate of iron in the mother liquor.
The formation of sulphates of iron from the sulphides, and the conversion of
the former into sulphate of soda, may also be carried on to a certain extent
simultaneously by mixing the common salt and the sulphides together, and
exposing them, slightly damped, in a heap to the atmosphere. When
spontaneous heat or chemical action in the heap has ceased or become languid,
the process may be completed in a reverberatory furnace, as usual. The
chlorine and muriate of iron, if any, and hydrochloric acid from these pro-
cesses, may be utilized by condensing towers, and other means already known.

page_text: By any of the above modes of operation, with the exception of the mode by
mixed solutions, a mixture of sulphate of soda and oxide of iron is obtained.
From this mixture either salt cake or crystallized sulphate of soda may be
separated, by the usual means of lixiviating with water, and may then be
applied to the manufacture of sulphuret of sodium and carbonate of soda, as
heretofore practised. The remaining oxide may then be used for the purposes
described under the ninth and tenth heads herein-after mentioned. Or the
mixture of oxide of iron and sulphate of soda may be applied directly to the
production of black ash, and the intermediate step of separating the sulphate
of soda avoided.
Ninthly, to the application of the residual "oxides" and other materials
from the foregoing processes to the manufacture of pigments. I heat the said
residual oxides and other residual materials with access of air, preferably in an
oven or reverberatory furnace, until the combustible parts are sufficiently burnt
off, and subject them to grinding, sifting, elutriation, or other known means
for finely pulverizing them; the residue from the sulphurous acid process
(fifth), however, and any oxides that may have been exposed to a red heat in
the soda and alum processes, may be used as pigments without the burning
herein described. It is desirable that the burnt oxides should be well washed
in order to free them from soluble salts of iron produced by burning off the
sulphur, and also from ammoniacal salts (should the latter be present), which
might impair the drying qualities of the pigments and the permanence of their
colours. I prefer to effect this washing before sifting or bolting, in order to
avoid the corrosion of the sieves by the salts to be washed out. The water
used for washing the said oxides may be evaporated to obtain salts of iron and
other substances. Any "spent " oxides of iron that may have had the sulphur
burnt off may be used as a pigment, as above described.
Tenthly, this relates to the treatment and application of the residual
"oxides" and other materials from any or all of the processes before described,
to render them suitable for repeated use in the purification of gas. The
residuum from which the sulphur and other vapours have been distilled or
sublimed under the first head is removed from the retort into water, or is
immediately quenched with water, and is the better for being exposed to the
air for a short time. The residue from which the sulphur has been expressed,
as described under the second head, may be reduced to powder, damped, and
then used with or without washing or further preparation. The residue from
the third and fourth, the burnt oxide from the fifth, and the residue from the
sixth, seventh, eighth, and from the ninth head (if any is available from the
latter), may also be quenched or damped with water, if dry, with or without.

page_text: extra burning or washing, and applied for the same purpose. The crude
sulphate of iron material from the sixth head may be intimately mixed with
quick lime, the mixture exposed to the air, and then used to purify gas; or
the mixture of sulphate of ammonia and oxide of iron from the same (sixth)
head may be again used for purifying, previous to separating the sulphate of
ammonia. In all cases the materials thus treated may be advantageously
added to or mixed with "oxides" that have been partially "spent," so as to
sustain their purifying power. I prefer, however, where it is convenient, to
pass the treated oxides through a bolting machine or fine sieve before using
them for purification. Those "oxides" that have been subjected to a red heat
(with the exception of the residual material from the seventh (alum) head) are
to be heated again in clay retorts or other suitable receptacles, and in the
absence of air to a temperature sufficient to reduce the iron to a metallic state."
The residue in the retort or other receptacle is then to be treated in the same
manner as directed for the preparation of sulphates of iron from the sulphides
of iron, under the sixth head of this Specification. Hydrated oxide of iron is
thus produced, which is more suitable for the purification of gas than the
anhydrous peroxide. Another mode of treating the burnt oxides is to mix
them with hydrated oxide of iron, or with magnetic oxide or carbide of iron,
either "fresh" or "spent," and use the mixture for purification.
Eleventhly, under this head I utilize the ammoniacal vapours given
off by "oxides" while undergoing the process of revivification, by passing
a gentle current of air through the reviving materials, and afterwards passing
this charged air through any "porous material" that will absorb the ammonia.
This may be effected in a simple and inexpensive manner by placing the
"fouled oxides," as they are removed from the purifiers, in shallow bins or
chambers of brick or other suitable material, provided with false floors,
bottoms, or tiers, say iron or wooden grids, or perforated plates or tiles, and
connecting the same to a chimney draught or suitable machine, regulated to
pass just sufficient air to renovate or renew the materials without injurious
heat. From the reviving bins or chambers the air is carried by the same
means through another bin, or through two, three, or more bins of like con-
struction, but provided in addition with covers; these latter contain the
porous absorbent. If the said absorbent is used in the same chamber as the
"fouled oxides," on separate trays or in layers, cocoa-nut matting or other
open fabric may be employed to prevent the materials from mixing one with
another. As soon as the absorbent has been sufficiently charged with
ammonia, fresh charges are put in, the fouled material being treated for the

page_text: extraction of ammonia or used as a manure.
be
Instead of placing the material
to be ventilated in bins or chambers such as I have just described, it may
laid in a closed apartment with openings to admit air enough for ventilation,
the only exit for the air being through a bin or bins or other suitable
receptacle containing the porous absorbent, where the air deposits or is
deprived of its ammonia, and is thence drawn into the chimney or exhausting
apparatus.
I wish it to be distinctly understood that in this Specification I have
indifferently and for brevity's sake made use of the terms "oxides used for
purifying gas,"
," "used oxides," "spent oxides," and "oxides," but by these
terms I do not mean "spent oxides" popularly so called, that is, oxides of iron
that can no longer be profitably used for purifying gas in consequence of the
large amount of impurity which they contain, but, with the exceptions herein
named, I mean all oxides of iron, including that oxide of iron sometimes called
"carbide of iron," that have been used for the purification of p gas from sulphur
and ammonia, or either of them.
Having now described the nature and particulars of my said Invention,
I would state I do not confine myself to every matter of detail, neither do I
claim all the processes or treatments herein described, but what I claim under
the respective beads herein mentioned is,―
Firstly, A, the use of ordinary horizontal gas retorts, that is, retorts which
have been set or used for gas making, or retorts similar thereto, for distilling
or subliming off the sulphur from "spent oxides" of iron that have been used
for purifying gas, with the exception of the magnetic oxide and carbide of iron
and spathose iron ore. This exception does not relate to any of the claims
herein-after stated. B, the distillation or sublimation of sulphur from "spent
oxides" of iron that have been used for purifying gas, by means of vertical or
inclined retorts, in which the process, if desired, may go on continuously.
C, utilizing, by distillation and sublimation, the ammonia or ammoniacal com-
pounds contained in "spent oxides of iron." D, the use of waste heat from
the arches or ovens of gas retorts for the above-named purposes of distillation
and sublimation of sulphur and ammonia. E, the direct production, by distil-
lation and sublimation, of "roll" or "stick sulphur" and flowers of sulphur
from "spent oxides of iron."
Secondly, the extraction of sulphur from "spent oxides of iron" by fusion
and pressure.
Thirdly, the extraction of sulphur from "spent oxides of iron" by digestion
in the liquids bercin-before mentioned under this head.

page_text: Fourthly, the extraction of ammonia and ammoniacal compounds from
spent oxides of iron" by lixiviating with water, substantially as herein-before
set forth.
65
Fifthly, A, the production of sulphurous acid gas from " spent oxides of
iron" by self-sustained combustion, substantially as herein-before described.
B, the utilization of the ammonia given off by "spent oxides of iron" while
burning, substantially as described under this head.
Sixthly, A, the production of sulphates of iron directly from the "spent
oxides of iron" when treated with limited access of air, substantially as de-
scribed. B, the production of sulphides of iron by heating, in the absence of
air, such "spent oxides of iron" as do not yield free sulphur by ordinary
distillation or sublimation. C, the production of sulphides of iron from "spent
oxides of iron" by mixing the latter with metallic iron, minutely divided, and
water, substantially as herein-before set forth. D, the production of sulphides
of iron from "spent oxides of iron" that contain an excess of sulphur by adding
to them metallic iron or oxide of iron and heating the mixture in the absence
of air. E, the production of sulphides of iron from "spent oxides of iron" by
adding metallic iron and fusing the sulphur in the mixture. F, the use or
application of any or all of the sulphides herein-before mentioned, as obtained
under the first and this sixth head, for the production of sulphates of iron.
G, the application of "spent oxides of iron" for the manufacture of sulphate
and sulphite of ammonia in the various modes, substantially as herein described
under the sixth head.
Seventhly, the use of "spent oxides of iron" for the manufacture of sul-
phate of alumina and alum either directly or by previous conversion into
sulphide of iron or into sulphate of iron.
Eighthly, the use of "spent oxides of iron" for the manufacture of sulphate
of soda, sulphuret of sodium, and carbonate of soda, either directly or by
conversion into sulphide of iron or into sulphate of iron.
Nintbly, the use of the oxides of iron and other materials resulting from the
foregoing processes under the first, second, third, fourth, fifth, sixth, seventh,
previous and eighth heads, for the manufacture of pigments.
Tenthly, A, the use of the residual oxides of iron from the second, third,
fourth, and sixth heads, for the purification of gas. B, the use of the crude
sulphate of iron materials from the sixth head for the purification of gas.
C, the use of the burnt oxides of iron from the fifth, eighth, and ninth heads
(when any is available from the latter), for the purification of gas, after being
treated or prepared for purification, substantially as set forth in the herein-
before tenth head.
1

page_text: Eleventhly, utilizing the ammoniacal vapours given off by oxides of iron
undergoing revivification, substantially by the means and apparatus herein
described.
In witness whereof, I, the said William Cleland, have hereunto set my
hand and seal, this Eleventh day of July, in the year of our Lord
One thousand eight hundred and sixty-two.
WILLIAM CLELAND. (L.s.)
In the presence of
JOHN THOMSON KING,
Patent Agent, 4, Clayton Square,
Liverpool.