IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID
Year: 1852

page_text: LETTERS PATENT to William Petrie, of Woolwich, in the County
of Kent, Civil Engineer, for the Invention of "IMPROVEMENTS IN
THE MANUFACTURE OF SULPHURIC ACID."
Sealed the 27th April 1853, and dated the 1st November 1852.
PROVISIONAL SPECIFICATION left by the said William Petrie
at the Office of the Commissioners of Patents, with his Petition,
on the 1st November 1852.
.
I, WILLIAM PETRIE, of Woolwich, in the County of Kent, Civil
Engineer, do hereby declare the nature of the said Invention for
"IMPROVEMENTS IN THE MANUFACTURE OF SULPHURIC ACID" to be as
follows:
When I obtain sulphurous gas.by burning sulphur, or such matter
containing sulphur as can be liquified by the heat.employed, I use itin
powder or broken pieces in a furnace which is open at one part
whether the opening for supplying the air be at the same part or
otherwise, but I consider it best to be at the opposite side), and the
first-named open part is stopped up by a mass of the said sulphur ör
sulphur-containing matter. The mass is supported-from-falling-too-far-
[Price 8d.]

page_text: into the furnace, either by a lattice work, orgrating (preferred of iron),
in which case I generally make the grating to have its openings of
this shape
or this
0
placed vertically, as regards their longitudinal
"1
perpendicular plane, and the widest side of the openings are next the
sulphur. This grating I generally incline'inwards to a certain extent
towards the furnace. Otherwise I make the sulphur support itself by
its own capability of piling at a certain angle or slope. In this case I
generally rest the aforesaid sulphur on a tile of non-heat-conducting
material, and sloping slightly towards the furnace, but not near so much
as the natural slope of the pile of such sulphur. The sulphuris heaped
up over the furnace opening, and as it becomes melted away it trickles
down on to a plate, or into a flat pan which slopes slightly towards the
opposite end or side. The sulphur burns as it glides along the pan, and
burns out as it approaches the opposite part. of the pan, where. the ash
or non-volatile matter accumulates, and is removed from time to time.
To regulate the rate at which the sulphur is melted and moves on
into the pan, I use an arrangement for directing more or less of the
heat of the furnace against the sulphur, and this may be done by many
modifications of means; for instance I use a fixed diaphragm or plate
of non-heat-couducting material parallel to the general surface of the
exposed part of the sulphur, and very near to it; and a register or
registers or slides direct the draught of hot gases either between
the said diaphragm and the sulphur, or on the opposite side of the
diaphragm, or partlyeach way,intherequired proportions. The registers
may be used to. regulate also the general draught of the furnace. Or,
as another modification of the said means, instead of the fixed diaphragm
and register or registers, I use a similar diaphragm or plate close
against the sulphur, and so arranged that it can slidė and be fixed in
such positions as to expose part of the sulphur to the radiated and
convected heat of the furnace, and protect the rest in the required
proportions. This slide may be so placed as to uphold a part of the
heap of sulphur, so that by changing the position of the slide the lieap
spreads or falls down more or less extensively towards the furnace.

page_text: I also use one or more narrow flues or channels under the tiles or
plates on which the sulphur rests, and under the plate or pan on which
the sulphur is burnt, whereby air is drawn, so as to remove undue heat
from the plates under the sulphur, and from the part of the plate on
which the melted sulphur first falls, and to heat the part on which the
last portions are burnt, so as to burn the ashes more perfectly. And
this air then passes, instead of other air, into the furnace, to support the
combustion of the sulphur; or it may partly or entirely pass away in
another direction.
The refuse ashes above named, and any other matter containing too
little sulphur to burn in the above-named furnace, I burn in a cylindric,
a parallelopiped, or a funnel shaped vessel or furnace. Hot air(from an
ordinary coke furnace for instance) enters at the sides of the lower part
of this furnace, and is drawn upwards through the mass; the lower
part of the hollow of this furnace extends downwards, below the part
where the hot air enters, and is open, but contracted at the bottom, in
such manner that the contents of the furnace rest on a heap of their
own ashes at bottom. Part of this heap is removed from time to time,
and this removal causes the whole mass in the furnace to fall down-
wards slightly. A little fresh air is continually drawn in at the bottom,
which completes the burning off of the sulphur, and cools the ashes, and
heats the air before it comes to the upper parts of the mass. There is a
door or cover over the top or at the side of the upper part, secured
with a close fit, or a lute of sand, dust, or mercury. This cover is
removed to throw in more of the matter to be burnt. A considerable
vacant space is left in the upper wide part of the furnace, below the
cover, to permit the dust to settle before the gases pass out of the
furnace to undergo further changes. Within the said cover I prefer a
funnel, fixed with its sides fitting close to the top of the furnace; and
this funnel is kept replenished with the matter to be burnt, so that the
interior of the top of the furnace is not exposed freely to the external
air at the times of replenishment. When the matter to be burnt lies
too close to admit of the air being drawn sufficiently freely through it,
I mix it with other matter for that purpose.
My object in the above named arrangements is to carry on all the

page_text: changes as completely as may be on the differential principle; a principle
by which two opposite changes, mutually dependent, are continuously
carried on, and effected thoroughly, instead of partially, in each respect
by a kind of compromise, or thoroughly, in one respect, by sacrificing
economy in regard to the other, as is the case in effecting such changes
by ordinary modes of merely bringing the different matters into contact
and action. By the differential principle changes are carried on con-
tinuously by a line of motion, or, of simultaneous and contrary motions,
of solids, liquids, or gases, from point to point, so that the total changes
shall be gradually effected by an insensible variation in the character
or degree of the change at each successive point as with each previous
one, while the circumstances of each point (or section of the line of
motion) remain constant, both in respect of the character and degree
of the changes taking place at it, and the composition or temperature
or constitution generally of any matter, if any; which is fixed at each
point, and of the solids, liquids, or gases, as they pass it in the same
or opposite directions.
་
I next pass the sulphurous and oxygenous gases into a differential
draught cell, like in many respects to that just described; what I term
a draught cell being a porous mass or collection of fragments of loose
material, through which gaseous matter is drawn or liquid matter
percolates, or both at one time, for the purpose of effecting changes (in
the chemical state of the matter employed) more completely, econo-
mically, or quickly than could be accomplised by some other means.
The porous material is enclosed in a case; by preference a vertical
hollow cylinder. In the present case it is of a tall cylindric shape,
made of stoneware cylinders,like short and wide drain pipes, with their
wide ends upwards; and the narrow or lower end of each succeeding
pipe upwards fits into the wide end of the one below it, and is cemented
in it. Their narrow ends are slightly contracted, and so shaped as to
shoot any liquid which drips down them clear of the sides of the next
lower pipe. In this cylinder are placed small bits of solid material of
certain kinds, as silicious gravel or pebbles, or of porous material of
certain kinds, as coke, or a mixture of these two. The bits are not to
have flat or concave surfaces, and are to be, as near as may be, of a

page_text: uniform size, and, as near as may be, half an inch in diameter, or,
rather, not large r than just such size that the capillary attraction ofthe
liquid used shall not fill up the spaces between them so much as to
arrest the greater part of the draught which the same force would cause
to pass through them if the liquid were not in such pores.
Water or weak acid is dropped into the upper end of this mass, and
is distributed over its surface equably by various means (by flushing or
dripping),such as with a hydraulic rocker; a known contrivance, which
throws the flow of liquid in sudden flushes first to one side and then to
the other: Or by a combination of these rockers conveying the liquid
from one to others, beneath, so as to subdivide the charge still further:
Or by a rocker so arranged that its reciprocating motion shall produce
a slow horizontal rotary motion in it, causing it to throw out its liquid
in various directions in succession: Or by a flat plate or plates of
porous ware, forming the bottom of a cistern, and having its underside
formed like a crossed" wafer stamp" only on a certain larger scale, so
as to distribute its drops uniformly. Where I use a rocker I also
combine a counting apparatus with it, so that its motion shall register
the amount of liquid supplied from time to time.
I keep the draught-cell insulated, and charged with electricity of
tension, so that the capillary attraction of the percolating liquid shall
be diminished, and the fragments or grains of matter occupying the
draught-cell may thus be much smaller.
To avoid certain difficulties and inconveniences, I support the loose
matter in the draught-cell, on a heap or mass of the said loose matter,
(which, however, may be advantageously coarser,) towards the outside,
so that the draught can enter through the sloping sides of the said heap
into its middle part, and thence upwards through the draught-cell
itself. Or I modify this arrangement, by having numerous holes look-
ing upwards, but slanting, and projecting a little in the sides of this
part of the draught-cell, instead of the heap of loose matter. I use an
arrangement similar to one of these for the purpose of letting the hot
air into the middle part of the last kind of sulphur furnace already
escribed.
I admit the hot mixture of sulphurous gas and oxygen, &c. at the

page_text: sides of this heap, or through the said holes, the heap'or holes being
covered over, all round the draught-cell, by a suitable casing (preferred
of stoneware).
::
The pan, which supports the under part of the sides of the heap
of loose material, extends downwards some depth in its middle part,
thus
and is filled with the loose matter, and terminates at
***
the lower part in a repetition of the said arrangement of a
heap (or holes) covered or cased over, and a pan beneath with
hole at its lowest part. The "said lower casing has holes in it to
admit air, which is regulated by the insertion of stoppers in some of
them.
'..t
1.
J..
J
The action is as follows:-Through a pipe leading from the interior
of the top of the draught-cell, the gases and vapors are drawn, and the
aqueous liquid percolating from above, and extending in thin filmsover
the large surfaces of the loose matter, 1stly, in the upper portions of
the draught-cell, 'absorbs oxygen, and the last portions of sulphurous
.gas from the gases, which are being drawn upand greatly agitated, and
mixed by passing through the narrow interstices of the loose 'matter;
2ndly, as it descends further, the pecular attractive power (probably)
of the extensive solid surface aids the absorbed gases to combine into
sulphuric acid; 3rdly, this weak liquor condenses the sulphuric fumės
which arise from below; 4tlily, in'descending further the liquor meets
the hot gases from the furnace, which evaporate waterfrom the liquor,
clarify it if discolored, and convert it into strong vitriol, or nearly so;
5thly, on passing down below the entrance of the furnace gases, the
specific action of the loose porous matter, and 'the agitation along
with the oxygenous air coming from below, combines the remaining
sulphurous gas (which it still may hold in solution) into sulphuric acid;
and 6thly, encountering the cold dry air from below, the acid becomes
cooled, and flows out at an orifice in the pan below, ready for use or
sale.
.
..
The drip of aqueous liquor from the top is to be regulated so as to
cool and aid the condensing power of the upper part of the draught-
:

page_text: cell as much as possible, without being so abundantas to overcome the
evaporative power of the heat of the gases, and weaken the resulting
vitriol more than necessary.
Most of the several operations above described as taking place in
succession, in distinct parts of the draught-cell, probably take placeto
some extent together in the same part of the cell.
The proportions of the parts and the draughts, &c. are so arranged
as to give effect as perfectly as may be to the already explained
differential mode of effecting the several combined operations.
A small quantity of nitric acid or nitrous gas may be used in the
aqueous liquor above, or in the furnace gases, before entering the
draught-cell, to effect the combination more rapidly.
(Process A.) The draught-cell may be divided by a stratum of finer
loose material, such as coarse silicious sand, just below where the fur-
nace gases enter; and the air rising from below should in this case be
diverted, either by holes in the side as before mentioned, or through
the piled sloping sides of the loose matter, or through a vacant interval
formed by a porous bottom, supporting the loose matter of the upper
parts of the draught-cell, and the air so diverted may be led away or
drawn into the furnace.
(B.) Also common air, previously heated, may be employed, instead
of furnace gases, to pass through that part of the draught-ce¹¹ which is
intended to concentrate the acid :
(C.) And the furnace gases may be somewhat cooled before they are
drawn into the proper part of the draught-cell:
(D.) And the cooling of the furnace gases may be made to heat the
before-mentioned air, for evaporating, or for other purposes, by an
apparatus of small pipes, like a locomotive steam boiler, in which the
furnace gases pass through the pipes, while the air to be heated passes
through in an opposite direction, between the pipes; thus again securing
the advantage of differential action.
The air from process A, may be heated by process D, to serve for
process B, and may then be passed into the furnace.
the
The divisions of the draught-cell for these purposes, and the exits of
gases, are to be effected as already described for process A; and

page_text: the inlet of the gases may be effected variously, but by preference as
described previously in the case of the gases from the furnace.
The above processes may also be performed by using the various
parts of thedraught-cell in separate places, and adapting them accord-
ingly, instead of one part over the other, or some parts of the com-
pound process may be performed by other means, many of which are
known.
.
The air admitted at the lowest part to cool the strong acid or vitriol
may be dried first by a draught-cell filled with loose frågments of a
matter which absorbs moisture, such as fresh burnt-lime. The cell is
formed and fed (with the lime) somewhat like the differential furnace
already described for burning sulphur out of such matter as ashes or
matter too poor in sulphur-to melt, only that in the present case no
hot air enters at the middle part, but only cold air from below. The
exhausted or hydrated lime is removed at the bottom, and burnt afresh
for throwing in at the top.
Instead of combining the gases from the furnace in a draught-cell
such as already described, I sometimes modify the process'in the fol-
lowing manner: I pass the gases through tubes or flues, or between
metal plates which are kept hot, or else I pass them through similar
means, or a worm tube, to cool them partially, if too hot; my object
being to get them to a certain temperature (between boiling heat aud
red heat) most suitable to promote in the following kinds of draught
apparatus
It consists of oxides of one or more of certain métals, chrome and
copper mixed being preferred; they are prepared by precipitation from
solution in a finely divided state, or filings or small grains, or precipi-
tated dust of certain metals, platinum being preferred, or of the before-
mentioned metals coated with their proper oxides.
I place a quantity of this powder in the bottom of a tall and very
taper funnel (with straight sides or trumpet shaped). Its neck below
is turned round, or a cup placed under it, so as to prevent the powder
from falling out. The hot gases (drawn from the sulphur-furnace or
source of sulphurous gas and oxygen) are drawn in at the lower end of
this funnel, which is clothed to keep it hot, and through it, with suffi-

page_text: cient force to support the powder in a diffused state, whereby greater
commingling of the gases is produced by the agitated grains of powder,
and the gas gets more freely at the surface of the grains (which from
their finenessis of enormous extent), instead of passing the gas through
or over a more close and stationary mass of the powder. The more
gentle motion of the gases in rising through the wider parts of the fun-
nel allows the finer parts of the powder to remain behind, instead of
being drawn over out of the funnel along with the combined gases.
I sometimes use the powder, instead of in the said funnel, in troughs
circular or straight, united in pairs parallel, and with spaces between
the pairs, and these spaces are covered by inverted troughs, whose
edges sink into the powder in each of the adjacent troughs, and the hot
gases being drawn up from beneath are compelled to pass through this
powder.
Or I sometimes use the said oxides in small grains or bits screened
to a somewhat equal size, and as small as will allow the draught at
command to draw sufficiently quickly through it; or filings, grains, or
granulated metal of certain kinds, as platinum, or spongy platinum, or
bits of thin platinum foil bent, or filings or grains or granulated metal
of certain other kinds, as copper or chrome, oxidized at the surface;
and I place these in the above-named system of troughs, or in a draught-
cell, such as already described, but in some cases without admitting
aqueous liquor from above, and the hot gases may be admitted at the
top in that case (or at the bottom otherwise, that is, when aqueous
liquor is admitted, and it should only be in such quantity as is neces-
sary to form vitriol), and the gases are drawn out at the other end.
Or the said draught-cell may have as its internal contents a number
of layers of wire gause of certain metals, as platinum, or of certain
other metals, as copper, with the surfaces properly oxidized.
Or the draught-cell may have as its internal contents a quantity of
foil of the metals in the above-named 'state, coiled closely in a convo-
luted form.
Or a long tube or a set of small tubes of the said metals in the said
state may be used, instead of the draught-cell.
In all cases in which plain metallic platinum is named as the com.

page_text: .
bining surface, it is to be well cleaned, for instance, by washing with
strong acid, then alkali, and then pure water.
•
From any of the above-nained modifications for combining thegases
to make sulphuric acid vapor, it is drawn into any suitable condenser;
for instance, a series of receivers surrounded by water or cold currents
of air, or left simply to radiate the heat, or having extensive flat upper
surfaces with edges holding water, or by cold air drawn in in sufficient
quantities along with the gases into receivers, or into a draught-cell
'containing suitable loose material, as silicious pebbles; to cause the cold
air to intermix thoroughly with the hot gases, and to catch the mist of
the condensed acid (it being preferred to draw the gases from the top to
bottom), or into a set of suitable tubes, such as glass, or without the
admixture of cold air the said gaseous matters may be drawn into aset
of tubes sloping towards their exit, and connected with the apparatus
which supplies the gaseous matters by cementation, or by lutes of
mercury, vitriol, or sand, according to circumstances, and kept in a
draught of coldair, or sloping into water, the side or bottom of the vessel
through which they pass, and which retains the water, being lined with
a sbeet of elastic material, as vulcanized caoutchouc.
But in cases when dry acid is being made, and the condenser is a
draught-cell, or a set of small tubes, the degree of cooling effected
should not be so great as to reduce the temperature below that at
which the dry acid solidifies; and I use with these condensers, and prefer
in the case of other kinds of condensers to follow this rule, and to have
a small tube leading downwards from the lowest part of the condenser,
.with a covered cup to lute the end, and the cup has a lip whence flows
the acid ready for use or sale, while from the exit end of the condenser
the waste gases are drawn off through an upper orifice by any con-
venient means of producing a sufficient draught.
"
I produce a draught where required in the manufacture of sulphuric
acid, by means of air bells or cells, single or compound, acting in series
or side by side, and luted with liquid, as water or mercury, and having
a reciprocating motion with guides or parallel motion, or rocking or
revolving on an axis with hydraulic valves, and actuated by a moving
power, as water flowing in a continuous stream. The water may be lcd

page_text: for this purpose into a hydraulic rocker turning on a double axis orline
of support, one parallel with the other, and on each side of its centreof
gravity when it is empty and horizontal, the support of these axes being.
attached to air cells acting by a reciprocating motion on an axis, and
there being a hydraulic air chamber to equalize the draught, otherwise I
accomplish the object by a known apparatus for producing a draught
by the falling of broken water or spray down a vertical shaft, or by
fanners, or chimney draught, &c.
I admit certain quantities of steam or water to the gaseous matters,
either before they are combined, or before they are condensed, when the
acid is not required dry.
I sometimes admit air to the gases where they pass from the furnace
to the combining apparatus, and at certain other parts, either for oxi-
dating or cooling. And when the acid is required quite dry, the air,
wherever admitted, should be previously drawn through an air drying
apparatus, such as I have already described.
In any arrangement for feeding the sulphur furnaces, I compose the
slides or diaphragms already-described, and the parts supporting the
sulphur of non-heat-conducting material, as tile, or of two plates, pre-
ferred of iron, having water or a continuous draught of fluid passing
between them for the sake of coolness; or in some cases I make the
draught which supports the combustion to enter by passing along the
surface of the parts to be kept cool. I modify the mode of supplying
the sulphur by using a vessel asa funnel or cylinder projecting through
the top of the furnace, and letting out the sulphur by an opening in the
lower part of this vessel, as the sulphur burns away; the sides of the
said vessel which are exposed to undue heat being kept cool by any of
the means already described.
Isometimes make each or any portion of the herein-before described
apparatus double, so that one part may be used while the counterpart
is being prepared for use.
I do not claim the general and known idea of oxidizing sulphurous
gas more completely by bringing the mixed gases into contact with
certain hot matters. But I claim the arrangement or use of that.
chemical fact in combination with one or more of the following parts

page_text: of apparatus adapted for working as a continuous and practical manu-
facturing process; namely, apparatus for drying air,a permanentsulphur
furnace, ora permanent source of sulphurous gas apparatus for bringing
the gases to their proper temperature, for the combining process
apparatus, such as I have already described, for combining the gases,
apparatus for cooling or condensing them, and the requisite means of
giving. to the air and gaseous matter continuous motion through the
aforesaid combination of apparatus. And some of my claims relate to
already described details of the various parts and processes. I claim
also various combinations of the above-described parts and arrange-
ments, especially the combinations of some of them with the above-
named means of oxidizing sulphurous acid. gas.
SPECIFICATION in pursuance of the conditions ofthe Letters Patent,
filed by the said William Pétrie in the Great Seal Patent
Office on the 30th April. 1853..
TO ALL TO WHOM THESE PRESENTS SHALL COME, I,
WILLIAM PETRIE, of Woolwich, in the County of Kent, Civil Engineer,
send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the First day of November, in the year
of our Lord One thousand eight hundred and fifty-two, in the six-
teenth year of Her reign, did, for Herself, Her heirs and successors,
give and grant unto me, the said William Petrie, Her special licence
that I, the said William Petrie, my executors, administrators, and
assigns, or such others as I, the said William Petrie, executors,
administrators, and assigns, should at any time agree with, and no
others, from time to time and at all times thereafter during the term
therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVEMENTS
IN THE MANUFACTURE OF SULPHURIC ACID," upon the condition (amongst
others) that I, the said William Petrie, by an instrument in writing
under my hand and seal, should particularly describe and ascertain the

page_text: 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 immédiately after the date
of the said Letters Patent.
NOW KNOW YE, that I, the said William Petrie, 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 thereof, reference being had to the Drawings
hereunto annexed, that is to say:
Firstly, my Invention consists of an improved furnace for burning
sulphur for the manufacture of sulphuric acid.
The object of the improvements are to secure a uniform rate of
burning; to have the power to regulate it independently of the draught
of the furnace; to facilitate the removal of the ash or residuum while
the burning goes on; to prevent the ash from forming a scum over the
chief burning portion, as this action, in the case of impure sulphur,
necessitates constant raking; and to save the cscape of gases which takes
place where the furnaces are charged from the doorway.
A furnace A, Figure 1, for burning sulphur, is constructed with an
open back end.
A grating B, covers this opening, and is fixed in an
inclined position; its bars are horizontal, and shaped and arranged as
shown in the section Figure 1, so that the drops of melted sulphur shall
trickle down the under side of them, and so that the loose bits or dust
of sulphur will not fall through, even though smaller than the spaces
between the bars. Behind this grating is placed a heap of sulphur C,
in loose bits or powder. A diaphragm D, extends across the back of
the furnace, very close to the grating, and partially protects the grating
from the heat, unless the hot gases of the furnace be made to pass
between the diaphragm and the grating. There is a slide or damper E,
at the top part of the diaphragin, so arranged that when pushed back
it shuts off the draught between the grating and the diaphragm, and
opens a passage in front of the diaphragm for the gates into the flue F.
In this position of the slide, the sulphur against the grating will be
melted at a very slow rate; but when the slide is pulled forward the
communication in front of the diaphragm from the furnace to the flue

page_text: is shut off, and that behind the diaphragm is opened, so that the hot
gases are made to sweep against the grating, whereby the sulphur is
rapidly melted.
When the furnace is in work, the slide should be so adjusted that
the sulphur will be melted just as fast as the resulting gases can be
properly condensed by the apparatus (of whatever kinditbe) into which
the flue leads them. The pan G, where the sulphur-chiefly burns, is
placed slightly inclined downwards.from back to front; the air enters
under the doorway H, and meets the liquid sulphur gliding towards it
from the back of the pan; as the sulphur burns away its gliding motion
carries the impurities of the sulphur along, and deposits them in front
of the part where the combustion chiefly goes.on, and the ash may be
removed by a rake through the doorway. Shallow.channels, or flues
an inch deep being preferred (they are not shewn in the section
Figure 1), are made just-beneath the bottom'of the pan G, on which
the sulphur burns, in such manner that a current of cold air may be
made to pass beneath the pan from its back to its front, so as to cool
the part where the sulphur burns most freely, and this air becoming
heated as it proceeds will impart heat to the front part, where the heat
so gained will aid to burn out the impurities there deposited; this air
then either passes through flues into a common chimney draught, or is
turned under the doorway H, in a closed channel, into the sulphur
furnace, to support its combustion..
The furnace may be of the ordinary modes of construction, so far asis
consistent with the action of the new parts which I herein describe, or
it may be modified in the ways shewn in the section Figure 1; where
the top of the furnace is formed by a cast-iron pan I, holding water to
keep the furnace from overheating, and to supply steam for other parts
of the process, for which purpose a cover of wrought sheet iron is to be
placed in the pan I, and the cover having-sides dipping beneath the
water forms a water lute'to retain the steam. The door H, may be
placed slanting, and may open by a sliding motion sideways. The flue
or chimney as represented is supported on the crown K, K, of an arch
spanning over the furnace itself. The division between the flue and
the stock of sulphur C,should be of non-conducting materials, as brick

page_text: dust or ashes, placed between iron plates. The diaphragm D, should be
non-conducting of heat; it may be of tile supported as represented in
Figure 1, in a cast-iron plate or framing; or it may be of cast iron
made hollow, and kept filled with water to supply steam whither it
may be wanted.
Secondly, my Invention consists in an improved furnace for the refuse
ashes above named; and any other matter containing too little sulphur
to melt by such heatas sufficient to burn off the sulphur is put in small
pieces into a cylindrical or rather a conical furnace composed of brick-
work, or of castiron clothed with brick work, as represented in Figure 2.
To keep the heat in, on the top is fixed a funnel M, into which the
charges of material are thrown from time to time. The funnel has a
cover N, fitting with a sand lute O. The charge in the funnel may be
stirred with a rod, which may be pushed down into the body of the
furnace when the material sticks fast; the air is drawn through the
mass by a flue or tube attached to the upper orifice P, which is in
connection with the apparatus for subsequently acting on the gases pro-
duced, and with some means of drawing them through, such as will be
hereafter mentioned. The form of the funnel secures a vacant space
around the upper part of the furnace, where the orifice P, is; this
facilitates and equalizes the draught through the mass of the material,
and allows the coarser dust to settle in the furnace. Hot air is
admitted at the middle part through a number of holes Q¹, all round
that part of the sides of the furnace; the holes communicate externally
with a flue R, passing round that part of the furnace; the flue may be
made of cast iron, with its joints closed with luting. The flue has a
branch S, which draws air from the open atmosphere; this air being
heated either by admixture with the products of combustion led by a
pipe or flue from a coke furnace, or by being drawn through iron pipes
passing through a furnace. The heat of the air should be sufficient to
volatilize the sulphur in the material so far as it may be considered
worth accomplishing. The furnace rests on legs T, shown dotted, or
on suitable framing, and is thus supported a short distance from the
ground; some of the exhausted material falls out at this opening, and
forms a trancated cone, on which the mass of the material in the

page_text: furnace rests. Portions of this cone can be shovelled away from time to
time, and this lets the mass in the furnace slip down for a short space
After each such removal more fresh material can be supplied to the
funnel at the top. Atmospheric air is drawn in through the sides of
the cone, which completes the combustion, and cools the exhausted
material, and this air becoming thus heated on the differential principle
aids the combustion of the fresh material above. There is a damper or
register U, in the hot air flue S; by this means the proportion of cold
air drawn in from the bottom can be regulated so that each portion of
the exhausted material shall have become nearly cold before it makes.
its appearance at the bottom, and thus but little, heat is wasted.
If the material to be operated on is of such a nature that the air
cannot be drawn through it properly, the material may be mixed with
other loose matter; and in some cases I prefer to dispense with the hot
air flue and its appurtenances Q, R, S, U, and to obtain the heat by
intermixing the material with a suitable combustible, as charcoal or
coke, in small irregular broken pieces. This species of furnace is appli-
cable to a variety of other purposes besides those claimed under the
title of the present Patent.
Thirdly, my Invention relates to improved means of condensing sul-
phurous gases. The sulphurous and oxygenous gases are next passed
into a differential draught-cell; what I here term a draught being a
porous mass or collection of fragments of loose material through which
gaseous matter is drawn, with or without liquid matter percolating, for
the purpose of effecting changes (in the chemical state of the matter
employed) more completely, economically, or quickly than could be
accomplished by some other means. The porous material is enclosed in
a case; by preference a vertical hollow cylinder. The draught cell A,
into which the gases are passed, is composed of short cylinders like drain
pipes of stone ware; but where the heat is considerable I prefer other
materials. Wedgewood ware of thin substance, or well glazed iron, may
be used, with their lower edges slightly contracted and bevilled down-
wards; they are clothed with brick work B, where there is much heat.
Into this is placed a quantity of rounded silicious pebbles, which are
generally to be about inch in diameter; water is dropped in at the

page_text: top of the mass, and dispersed equally over its surface a, from a cistern
D, kept constantly supplied by a tap; the bottom of the cistern C,
being formed of aflat horizontal plate or plates E, of very coarse porous
pottery ware, such as Wedgewood material, cross grooved at its under-
side like a wafer stamp, but on a much larger scale; the thickness of
the plate and the porosity of the ware being so adjusted that the water
shall drip through at the required rate when there isa few inches depth
of water over it,and so that the plate E,shall not be less than thedepth
of its cross cuts in its thickness above them. Or the water may be
equably dispersed by means of a hydraulic rocker F, Figure 5, which is
a horizontal trough having a longitudinal vertical division G, down its
middle, and balanced upon an axis or spindle H, coincident with the
lower edge of the said division. The cross section of the trough is such
as represented Figures 4, and 5; that when water from the funnel or
cistern d,vertically over the axis of the trough,partially fills one side of
it,then it overbalances, and suddenly throws that portion of water out
by the longitudinal orifice I, and the other side begins to fill. The
water falls ther.ce forashort space so as to splash and disperse; and to
aid this, a grating. Figure 4, (of glass, stoneware, or glazed iron, &c.)
is placed just above the loose matter C, of the draught-ccll. Or, to dis-
perse the water yet more equably, 1 make the main rocker F, Figures
3, and 4, to discharge its contents into several smaller rockers /,placed
crossways beneath it. For this purpose there are small orifices L, in it,
to let the water flow out more gradually than if there was the wide lon-
gitudinal orifice; and divisions M, are fixed across the trough, so that
when one side is turned up for the water to enter, it can flowever them
and fill all parts equally; but when that side falls lowest the divisions
retain a portion of water over each orifice proportionate to the surface
over which the smaller rocker beneath has to disperse its water. Each
rocker has a bar or bars N, crossing beneath it; to prevent its rocking
too far over either side. The rockers and other parts may be made of
well glazed iron. The bars under the rockers should not be too hard,
but made of wood, or else coated with caoutchouc in cases where the
heat is not great. To avoid certain difficulties and inconveniences in
the usual modes of supporting the loose matter C, in the draught-cell;

page_text: and in letting a draught into it at its lower end or at its middle parts, I
support it on a truncated cone or mass O, Figure 8, of the said matter
(which, however, may advantageously be made rather coarser towards
its outside). The draught can enter through the sides of the cone into
the middle part of the mass,and pass upwards.Or,instead of the sloping
sides, the mass may be retained by a prolongation of the sides of the
draught-cell, with holes Q, Figures 6, 7, and 9, in it, with small bits of
pipe attached,and extending into the cell in a sloping direction, or with
small inverted troughs thrust through the holes transversely into the
draught-cell (as shown in plan Figure6). One mode of operating on
the sulphurous gases is to use such a draught-cell, Figure S, as that of
which the parts have just been described. At its lower end is one of the
arrangements for admitting a draught; this part is cased over P,and an
orifice R, admits air into the case. The air admitted here may be
dried first by drawing it amongst bits of quick lime or other known
methods; in this case it is led into the orifice R, by a close fitting pipe.
There is another similar arrangement about six feet higher for admit-
ting, by an orifice S, the hot gases from the furnace at about the tem-
perature of boiling vitriol. The column of loose material C, extends
upwards for about sixty feet above this, with supply of water diffused
over its upper surface, as already described; the water falls through a
vacant part of the case of the draught-cell, in which part there is the
outlet orifice or vent V, for the gases, which are drawn throughout by
means of a pipe leading to a known apparatus for producing a draught,
by means of the falling of broken water or spray down a vertical shaft,
or to an air holder or bell inverted in water in the usual manner, and
properly balanced for obtaining an equable and sufficient suction
draught, this air holder being connected by a pipe in the well known
manner to another air holder furnished with valves, and caused to move
and down, so as to pump the air from the first-named air holder;
otherwise a sufficiently powerful chimney draught, or fanners, or other
known mcans, may be used to draw the gases through the draught-cell.
In this case the effects are as follows:-The aqueous liquid percolating
from above, and extending in their films over the large surface of the
loose matter, first, in the upper portions of the draught-cell, absorbs
up

page_text: the final portions of sulphurous gas a
and oxygen
from the gases which
are being drawn up and greatly agitated, and mixed by passing through
the narrow interstices of the loose matter; secondly, as it descends
further, the peculiar attractive power (probably) of the extensive solid
surface aids the absorbed gases to combine into sulphuric acid;
thirdly, this weak liquor condenses the sulphuric fumes which arise
from below; fourthly, in descending further, the liquor meets the hot
gases from the furnace, which evaporate much of the water, and clarify
it if discolored, and convert into vitriol, or at least acid of considerable
strength; fifthly, on passing down below the entrance of the furnace
gases, the acid encounters the cold dry air from below, and becomes
cooled; sixthly, the agitation, along with the oxygenous air from below,
and the specific action of the extended hard surface, combines the
remaining sulphurous gas, if any, into sulphuric acid; the liquid pro-
duced then flows out at an orifice X, in the bottom of the draught-cell,
and is ready for use or sale.
Most of the several effects above described as taking place in suc-
cession probably take place to some extent together, in various parts of
the cell. The apparatus is so arranged as to give effect, as perfectly
as may be, to the differential mode of effecting the several combined
operations. The drip of aqueous liquid from the top is to be regulated
so as to cool and aid the condensing power of the upper part of the
draught-cell as much as possible, without being so abundant as to
overcome the evaporative power of the heat of the gases, and weaken
the resulting acid more than necessary. There is a register or damper.
(not shown in the Drawings) to the draught from the furnace, to
regulate it, to supply just so much gas as the draught-cell is capable
of properly converting into sulphuric acid, which will be indicated
by the smell of the gas drawn off from the vent V, above; and there
is another damper (not shown) to the draught of dry cold air below, to
regulate it, to cool the outflowing acid sufficiently, and to furnish a
sufficient excess of oxygen to the furnace gases if needed, but not so
much as to cool or dilute the furnace gases unduly. A small quantity.
of nitric acid or nitrous gas may be used in the aqueous liquor above,
to effect the combination more rapidly. If the acid produced be dis-

page_text: colored, as by carbouaceous matter from the furnace gases, or from the
aqueous liquor used, then the pebbles of the draught cell just below the
entrance S, of the furnace gas, are replaced by a quantity of broken
pumice.
The draught-cell may be modified, Figure 9, for the purpose of
obtaining the advantages of conducting the chief part of the condensing
process with cooler gases, that is, at considerably less than boiling
heat. For this purpose the furnace gases are admitted at the orifice
S, Figure 9, as before; but after they have ascended sufficiently far
to evaporate the water from the descending acid, they are led out of
the draught-cell by an orifice T, just below which the loose matter
terminates, and leaves a vacant space in the case of a cell, and just
above which there placed a horizontal division Y, to support the super-
incumbent loose matter; but to let the acid pass straight down, this
acid is made to fall equally over the aforesaid lower surface of loose
matter (below 'T') by any of the herein-before described means of dif
fusing the liquid at the top surface of the draught-cell. The furnace
gases, on passing out at the aforesaid orifice T, are cooled, for instance,
by the well-known contrivance of a worm of lead or stoneware or
Wedgwood ware, the worm being so arranged as to level that any acid
condensed in it may flow, along with the uncondensed gases, through an
inlet U, into the upper part of the draught-cell just above the division
Y, thence the pass upwards, and are condensed as in the previous case,
Figure 8. In some cases, especially when the furnace gases contain
nitrous gas, it is desirable to use other air to concentrate the acid. In
this case cold air is drawn in at the lowest orifice (R, Figure 9,) as
before. Hot air (about 600°) is drawn in at the next orifice S, and on
passing out at the next orifice T, charged with sulphuric fumes and
nitrous gas, it is turned into the furnace or the pipe conveying the
furnace gases; and all these gas combined, and suitably cooled, as before
said, are led into the draught-cell (at U) just above the division Y,
whence they proceed as before. When nitrous gases are used, the
height of the upper part of the draught cell may be greatly reduced
with advantage. The cooling of the furnace gases may be made to
heat air for the said purpose of concentrating the acid, or for other

page_text: purposes, by an apparatus already publicly known, consisting of small
pipes like a locomotive steam boiler, of platinum, glazed iron, or
Wedgwood ware, for instance, in which the furnace gases pass through
the pipes while the air be heated passes through in an opposite
direction between the pipes, thus securing the advantage of the
differential action. Instead of combining the gases from the furnace
in such draught-cells as are already described, I sometimes modify
the draught-cell by using it on a very small scale, a few inches or feet
in height, and about a foot in diameter, or less, according to the rate of
action desired; and instead of loose silicious or other matter, I charge
it with platinum in such a state as to expose a large surface with very
little bulk, such as thin shavings of spongy platinum, or filaments of
asbestus coated with platinum. I prefer to support the platinum on a
fiue network of platinum wire, through which the furnace gases are
drawn; or the draught-cell may be formed entirely of a number of
layers of fine platinum wire gause. In all cases the platinum should
have been well cleaned (if not so originally) by washing with strong hot
sulphuric or nitric acid, then with an alkaline solution, then rinsing in
distilled water. The sulphurous gas, before it is led into this draught-
cell, is brought to a suitable temperature between that of boiling water
and a low red heat, by generating the gas in a furnace the sides of
which are not kept too cool, and the gas is led through pipes exposed
to a current of air, and just so much protected with cinders as will
cause the temperature in the draught-cell to be such as will produce
the most rapid and complete oxidation of the sulphurous fumes. Or, to
accomplish the same object, cold air is admitted by a register in the
pipe or flue which leads the furnace gases to the draught cell. No
water is admitted to the draught cell, and the sulphuric fumes are led
into a dry draught cell charged with silicious matter like the improved
draught cell herein-before described, and about forty feet high. Sul-
phuric fumes condense, and the uncondensed gases are drawn away at
the top. The air admitted to the burning sulphur and otherwise to the
gases in this process may be artificially dried, and the condenser or
silicious draught-cell kept warm (between and degrees of
Faranheit), or else steam or moisture may be admitted between the

page_text: platinum and the silicious draught-cell, or water may be admitted
through the top of the latter, according to the quality of acid required.
In theabove arrangements the draught of suction is produced as in the
cases herein-before described. I also obtaina draught for the draught-
cells by a known apparatus for producing a draught by the fall of
broken water or spray down a vertical shaft, and as a substitute the
use of air holders for the same purpose arranged in well-known ways.
I also use the platinum oxidation in connection with a double set of the
apparatus for supplying the gases, each set being work alternately.
And having now described the nature of my said Invention, and the
manner in which the same is to be performed, 'I declare that I claim, in
respect of the first head of my Invention,-First, the construction of
the sulphuric furnace with an open space, which is kept filled up with
the sulphur (or sulphur-containing matter, such as can be liquified by
the heat of the furnace), so that the gas from the furnace cannot much
escare to any great degree through the said open space; while also the
furnace is so formed that the said matter with which the furnace is fed
shall take a position so far in the way of the current of the hot gases,
or of radiated heat derived from them, that the said matter shall melt
as fast as it is required to supply .the furnace, and shall glide into the
pan or the adjacent parts of the furnace where the combustion proceeds
and leaves the incombustible products. And in connection with the
above-named arrangement I also claim the following particulars:-
First, preserving the sulphur or matter aforesaid in its proper position
for becoming melted, and for running further into the furnace, by
supporting that part of it next the interior of the furnace in the afore-
said arrangement, on or against a grating or bars. Secondly, the use
of one or more slides or dampers, and a diaphragm at or near the
aforesaid sulphur, the diaphragm being so placed as to partially screen
the said sulphur from the access of the hot gases; and the damper or
dampers being so placed and used as to regulate the proportion of hot
gases which shall pass between the diaphgrain and the said sulphur, so
as to melt it away at the required rate.
Secondly, I claim the use of very shallow flues orchanels beneath the
pan or plate on which the sulphur is burnt, the arrangement being such

page_text: as to cause a current of cold air to pass from that part of the pan which
is required to be kept :nost cool to that part which it is desirable to heat,
or which it is not so desirable to cool.
Thirdly, I claim the use of a draught-cell or furnace adapted to
transform sulphur into a gasious state for the purposes of this
Invention, when the sulphur is associated with so great a proportion
of impurities that the material will not melt by the application of
the heat requisite to expel the sulphur, the said furnace being con-
structed so as to have the differential principle of action, the raw
material and the air being made to move through it in opposite
directions, provision being made for gradually feeding the furnace
at its upper part, and gradually removing the exhausted products at
its lower part, without interrupting the continuous operation of the
furnace. And in connection with the above-named arrangement,
I also claim such a construction of the furnace as causes hot air to
enter the mass of the material at an intermediate point between the
upper and lower part of the material, to promote volatilization of the
sulphur, and at the same time cold oxygenous air to enter the mass of
the material at its lower part, so as to burn off any remaining sulphur,
and with it to carry back the remaining heat left in the exhausted parts
of the material. I do not claim the use of any particular kind of
material or mixture for feeding any modification of furnace herein.
before described, whether the material contain anyother combustible
besides sulphur, and is capable of developing its own heat sufficiently
for continuing the combustion, or needs an entraneous supply of heat.
Fourthly, I claim the construction of draught-cells for any of the
purposes of this Invention, with the following improvements on those
which are now in use, that is to say:
Firstly, I claim the use of a particular kind of drip stone for the
same purpose, namely, a flat plate of a material just so porous that it
shall let the liquid drop through at the required rate, and forming the
horizontal bottom ofa cistern supplied with the liquid, the under side of
this bottom having a number of prominences made in the substance of
the material, and each sufficiently small to admit of a sufficient number
to distribute the liquid with the requisite uniformity, and yet not so

page_text: small that the liquid might be drawn over by the syphon-like action
of the capillary attraction of the surface-from one prominence to a
neighbouring one which may happen to project a little lower.
Secondly, I claim the use of an hydraulic rocker, or a combination
of hydraulic rockers, for the purposes of distributing liquid matter as
equally as may be over the perous matter of a draught-cell. By the
term hydraulic rocker I mean a receptacle into which the liquid is
caused to pass, and which is so fashioned, balanced, and arranged, that
it shall have reciprocating motion, and cause intermittent flushes of
liquid to fall or run, either in a body on to the perous matter of the
draught-cell, or else that it shall cause the liquid to fall or run either
suddenly or more gradually into other hydraulic rockers.
Thirdly, I claim the means herein-before described of supporting the
lower part of the vertical colum of porous matter in a draught-cell
(that is to say): I claim the method of supporting she porous matter on
a truncated cone or a heap of its own metal resting on a solid bottom
not pervious to the gases used, which are made to pass in through the
sides of the cone exposed beneath the termination of the solid sides of
the draught-cell. Or, for convenience, I continue the sides ofthe draught-
cell straight down to the solid bottom, and make in that part of the
sides a number of holes inclined upwards towards the outside, or ex-
tending inwards, or a modification of this extension, that is to say, the
use of inverted troughs fitting in the holes loosely, and placed horizon-
tally, through the loose matter for a short distance, or else from one
hole to another. In this case the keep, on which the porous matter
above rests, instead of being retained by its own sloping sides, is retained
by the sides of the draught-cell extending downwards around it.
Fourthly, I claim the use of the above-named arrangements (of a
truncated cone of the loose material, or of the said holes inclined or
otherwise modified and arranged as described, to admit gases at án
intermediate part ofthe draught-cell, between its upper and lowerend.
Fifthly, I claim the combined use of all or any five out of the six of
the following things or arrangements for the construction of draught-
cells for preparing sulphuric acid:-a, forming the case or inner lining
of the draught-cell by circular pipes like drains, of such materials as

page_text: stoneware or Wedgewood ware, placed upright, the lower end of one
fitting into the upper end of another, and contracted and so shaped
at the edge as to shoot any liquid that may drip down them clear
of the sides of the next lower pipe b, using for the loose matter
within the cell pieces of matter, solid or porous, according to certain
rules; namely, solid material, such as flint or quartz, in cases where
the desired action is accomplished by the exposure of an extensive
surface of the liquid to the gaseous matter, and where at the same
time but little is required of the peculiar action of the solid surface
to effect the oxidation or combination of the fluid matters used; and,
on the other hand, using porous material, as pumice or porous cake,
where there is needed little or no exposure of the liquid to the gaseous
matter, but where the desired action consists in mainly or entirely
the afore-mentioned peculiar combining action of the solid surface,
and using a mixture of the solid and porous material in proportion
as these two actions are needed. c, using the solid material of a
rounded form, not concave or angular. d, using the said pieces of
solid material of a uniform size, as near as may be. e, using them of a
particular size, namely,just such size that the capillary attraction of the
liquid used shall not fill up the spaces between them so much as to
arrest the greater part of the draught which the same force would
cause to pass through them if the liquid were not in such spaces.
Passing the liquid on the gaseous matter in opposite directions through
the cell in every case, so as to secure the full economy and efficacy
of differential action, which action has in most cases only taken place
accidently, and has not been designedly provided for. Except that I
do not claim the use of the last-mentioned combinations of improve-
ments marked fifthly for the purpose of concentrating the acid without
effecting any other change in the same column or fall of the acid.
Sixthly, I claim the application to draught-cells for making sulphuric
acid of the known apparatus for producing a draught by the falling of
broken water or spray down a vertical shaft, and as a substitute the use
of air holders for the same purpose, arranged in well known ways, as
already described. The artificial drying of atmospheric air for the
furnace, or for admission to draught-cells, in processes herein-before
described.
-

page_text: -Seventhly, I claim the application of a draught-cell, whether of the
improved construction or not, and in connection with a suitable means
of draught, to effect the following objects severally, on the differential
principle, as herein-before described:-
"
Process 1st. By aid of aqueous liquid to absorb and to oxidize
certain compounds of sulphur, as sulphurous gas, into sulphuric acid,
without the aid of a volatile oxidator, as nitric or nitrous acid.
2nd. o clarify.strong acid by the joint action of the extensive solid
surface arranged suitably therefore in the dranght-cell, aided by the
strength of the acid, considerable .heat, and oxigenous air, and also
without the latter.
3rd. To cool sulphuric acid by the cold air passing through, whether
dried or not.
I do not claim what I hereby call Process 4, namely, the con-
densation of sulphuric fumes by a draught-cell; but I do claim their
condensation by that apparatus in combination with an apparatus for
oxidating the less oxidized gases without water or nitrous matter. I
do not claim a separate process which I here call the fifth, namely,
the concentrating sulphuricacid by adraught cell of any sort whatever;
but I do claim the use of the hot furnace gases for the latter purpose.
I also claim the following combinations in different parts of one and
the same fall, taking Process 1, with or without a volatile oxidator;
Process 1, with 5; Process 1, with 5, and 2; Process 1, with 5, and
3; Process 1, with 5, and 2, and 3; and Process 4, with any of these
combinations.
.
Eighthly, I claim the particular system herein-before described,
Figure 9, for working sulphurous gases, &c. when mixed with nitrous
gases through a draught cell,that is to say, concentrating, cooling, &c.
the resulting acid by hot air, and leading that air, with the products
with which it is charged, along with the gases from the furnace, into
the lower part of the upper division of the draught cell, or into a similar
apparatus, though it be not vertically over the other.
Ninthly, I claim the use of a soluble oxidating medium,as nitric acid,
in the aqueous liquid supplied to a draught cell, adding any of the
improvements claimed under the 4th head of my Invention.
Tenthly, I claim the application of the known tubular apparatus

page_text: herein-before mentioned to cool the gases from sulphur furnaces, and to
obtain their heat in common air to apply to other purposes.
Eleventhly, I claim the use of an extended surface of certain not
volatile solid matter, as platina, which I call a stereo-oxidator, through
or over which gaseous compounds of sulphur, as sulphurous gases and
oxygen, are made to pass, in combination with a permanent sulphur
furnace apparatus for regulating and securing the proper temperature
in the gases passing to the said stereo-oxidator, an apparatus for
condensing the fumes and draught power. I do not confine myself to
particular forms of these parts of apparatus used in connection with the
stereo-oxidator, although I have herein-before described particularly
what I think well suited to the purpose.
Twelfthly, I claim the use of the stereo-oxidator in connection with
a double apparatus, as before described.
In witness whereof, I, the said William Petrie, have hereunto set
my hand and seal, this Thirtieth day of April, One thousand
eight hundred and fifty-three.
WILLIAM PETRIE. (L.s.)