IMPROVEMENTS IN THE MANUFACTURE. ⚫ OF SULPHURIC ACID AND IN APPARATUS EMPLOYED THEREIN, PARTS OF WHICH IMPROVEMENTS ARE APPLICABLE TO THE OBTAINING OF DRAUGHT, TO THE, CONDENSING OF GASES, AND TO THE CONSTRUCTION OF FLUES
Year: 1860

page_text: LETTERS PATENT to William Petrie, of Woolwich, in the County of
Kent, Chemist, for the Invention of "IMPROVEMENTS IN THE MANUFACTURE.
⚫ OF SULPHURIC ACID AND IN APPARATUS EMPLOYED THEREIN, PARTS OF WHICH
IMPROVEMENTS ARE APPLICABLE TO THE OBTAINING OF DRAUGHT, TO THE,
CONDENSING OF GASES, AND TO THE CONSTRUCTION OF FLUES."
Sealed the 12th February 1861, and dated the 16th August 1860.
PROVISIONAL SPECIFICATION left by the said William Petrie, ut the
Office of the Commissioners of Patents, with his Petition, on the
16th August 1860.
I, WILLIAM PETRIE, of Woolwich, in the County of Kent, Chemist, do
hereby declare the nature of the said Invention for "IMPROVEMENTS IN
THE MANUFACTURE OF SULPHURIC ACID AND IN APPARATUS EMPLOYED THEREIN,
PARTS OF WHICH IMPROVEMENTS ARE APPL.CABLE TO THE OBTAINING OF DRAUGHT,
TO THE CONDENSING OF GASES, AND TO THE CONSTRUCTION OF FLUES," to be as
follows:-
My improvements relate in part to the columns previously invented
by me for effecting the requisite changes in the gases, and in part to
other apparatus used in producing and concentrating sulphuric acid.
In describing the new arrangements I shall briefly describe some of

page_text: the old parts, also where connected with the improvements and where
they might otherwise not be exactly understood.
I use stoneware cylinders placed vertically in a bottom piece, and
filled with granular material somewhat like coarse sand. The bottom
piece is contracted downwards near the bottom with a curve of con-
trary flexure as its vertical section, and from the circle forming the base
of this contracted part a dome rises so as to form the central portion
of the bottom. This form has particular advantages. At or near the
bottom- there is a small horizontal hole with a hollow tube or spigot
ground into it for the outflow of liquid. Around the sides of this bottom
piece are holes, one for the inlet pipe of the gases or atmospheric air,
and others stoppered for other purposes. Above the holes internally
is a flange, on which rests the outer edge of a horizontal ring, from the
inner circumference of which a short hollow cylinder extends
downwards, preferably a little below the level of the centres of the holes.
The aforesaid granular material does not occupy the annular space
between the exterior of this cylinder and the interior of the sides of the
bottom piece. Above this bottom piece I cement what I call an inter-
mediate piece of the same form and similarly furnished with a ring
piece, but instead of a dome springing from its contracted lower cir-
cumference this rests on and is cemented into a socket forming the upper
circumference of the bottom piece. Test pipes open at both ends and
slightly inclined to the horizon, and having longitudinal slits in the
flattened and hollowed upper side extend through the column and are
each cemented in two holes 120 degrees apart in one of the cylinders.
Samples of the liquid and gas existing at that level in the column can be
taken from the lower and upper ends respectively of these test pipes
which are otherwise kept closed, the lower end by a hollow stopper open
at its inner end so that a sample of the liquor can accumulate therein,
the upper end by a solid stopper to be removed, and a tube to be fitted
to it when it is required to withdraw a sample of the gas by suction, as
in well understood ways. The granules of the material filling the column
are composed of such material as compact carbon or silex individually,
solid grains of coarse sand for instance, of rounded form, but, rough (not
polished) exterior are desirable, and of sufficiently equal size, that is the
mean diameters of as much as may be of it are to be between two dimen-
sions, the larger of which is not more than double the smaller. The per-
meability to gases depends on the above points. The positive size of
the medium granules depends on circumstances, and is determined by a
particular rule, it is generally between 1 and 24 inch. The oxidizing
and condensing power depends chiefly on this point and partly on some
of those above named. The column is covered by a dome, and around

page_text: its inclined sides are sight holes covered by a moveable piece of plate
glass resting on a small ring or bead surrounding the hole and ground
to a true plane. I overcome some practical difficulties by forming the
dome in two separate concentric parts, firstly, an external or circum-
ferential part carrying the outlet socket for the gases pipe and the sight
holes, and secondly, a central part of the dome with a central hole fitted
with a spheric jointed funnel for the inflow of liquid, with a long beak
dipping into a narrow cylindric cell to trap the draught. The cell is
pierced near its top with small holes occupying a horizontal ring around
it, and above each hole is a notch for preserving the overflow equable
all round the cell in case of an excess of liquor passing through. The
cell hangs by a collar just below the holes in the upper circumference
of a hollow obtuse truncated cone resting its base on an internal flange
in the top of the external dome, and having radiating channels con-
veying the liquid from the small holes and dropping it into drip channels
on the flange of the external dome, and thence into their several sets of
branching shoots placed beneath, and so contrived as to lead the liquid
in approximately .equal driblets to points equally distributed over the
surface of the granulated material. In the case of smaller columns the
conical plate with its radiating channels fills the area of the column, and
rests in the same socket as the dome on the uppermost plain cylinder.
The dome is made in a single piece in this instance, and holes are so
formed in the plate as to cause the liquor to drop at points equally dis-
tributed over the granular surface while the gases also can rise freely
through these holes.
To obtain an equable flow of liquid, where required, into the columns,
or elsewhere, I use a cistern, preferably a stoneware jar, having a
cover air-tight, preferably a patent spheric, fitting and furnished below
with two cocks, one entering the jar preferably close to the other, but
at a little higher level, has preferably a smaller bore to admit air, and
its orifice is also at a slightly higher level than that of the other, both
of them dip into a small vessel, when both cocks are open they cease to
discharge liquor as soon as it rises in the vessel up to the orifice of the
higher cock. The two cocks may be made otherwise in the form of one
with two bores or ways. The jar is also fitted at its upper end, with an
inlet tube for liquor, trapp'd by dipping into the supply tank below, and
with a small tube, whereby the air can be exhausted from it so as to
replenish it with liquor. The syphon used for withdrawing liquids from
the said vessel, and otherwise, is of so small a bore as to clear itself of
any air bubbles, as soon as they enter, and is contracted at its inflow,
and turned up at its outflow end at somewhat higher level than the
inflow, and is fixed at any required level according as it may be desired

page_text: .to alter its rate of flow, or to cause it to cease flowing in a filtering
cylinder standing in the vessel of liquid.
The outflow of liquid from the bottom of one column into the top of
another next below it is not carried direct by a pipe, but is arranged
so as to present continuously a portion for sampling and an automatic
gauge of its rate of flow, as follows:-The spigot of outflow, dips into a
narrow deep vessel to trap the pneumatic suction, this vessel stands in
a second vessel connected by a contracted syphon, so that the difference
of level of liquor.indicates the rate of flow, while this second vessel dis-
charges into the funnel in the top of the next column by a syphon,
instead of a plain overflow, thus no height is lost between the columns
by the depth of the trap required.
When the power of suction draught is obtained by a steam blast,
either for these columns or for chambers, or other arrangements in the
production of sulphuric acid, or for other purposes, I obtain the power
with unusual economy by directing the jet through the axis of a cylindric
tube having a conical outlet taking care to have these rightly propor-
tioned, namely, the jet, truly central and axial, cylinder length from
jet hole to conical end 20 diameters, conic prolongation of cylinder to
expand to 1 diameters in its length of 10 diameters, or for more com-
plete economy of power, to expand to 2 diameters in a length of 20
diameters the actual diameter of the cylindric part of the pipe should
be x that which would oppose as much resistance (to the steam used
and the gases unitedly) as the whole apparatus of columns opposes to
the transit of the intended volume per minute of gases, the pressure of
steam should be as great as is admissable by practical convenience,
ruled by the consideration that the consumption of fuel, ceteris paribus
depends chiefly on the inverse square root of the pressure, then these
several circumstances being brought about, the diameter of the steam
jet nozzle soould be made such as will produce the last above-named
amount of suction force, at the same time that the gases are intended
to flow as intended from the apparatus.
In lieu of the usual chambers and other apparatus at present con-
nected with them to convert sulphurous gas into sulphuric acid, columns
constructed as aforesaid are arranged in the following manner; - The
sulphurous gas at a temperature of proferably about 120° Fahrenheit
.is led into the beforenamed intermediate piece of a first column, the gas
passes thence by a stoneware pipe into a second column constructed
without an intermediate piece, (as also are the other columns except
the fifth), 'then it is raised to a temperature preferably 150° Fahrenheit
as by a jet of steam, or by passing it through a heated pipe, and thence
into a third column, and thence into a fourth, the granular material of

page_text: which is about thrice the diameter of that of the others, and thence the
remaining uncondensed æriform matter is drawn out by its outlet pipe,
terminating in a suction, draught. Into the third column a small stream
of water runs by the before-mentioned means or otherwise, and it is
preferred to be somewhat acidulated with any waste sulphuric or nitro-
sulphuric acid, to reduce its tendency to evaporate from the third into
the fourth column, this water absorbs and oxidizes nitrous gas passing
through the third column, and is made to flow out by the before-men-
tioned means into the second column, placed sufficiently low, where it
absorbs sulphurous gas, and generates sulphuric acid, which containing.
also nitrous acid, flows out into a stoneware vessel, where a glass syphon
is arranged as already described, and regulated to draw part of it into
the first column placed sufficiently low, while the rest overflows by a
lip into a covered jar or cistern, whence it is occasionally raised into
the hermetic jar, fitted and worked as already described, and thus
returning the liquor continuously into the second column. The liquor
percolating through the first column loses its nitrous acid and flows out
as pure sulphuric acid into a receiving vessel, or into a concentrating
apparatus. Into the fourth column, a regulated and very small stream
of strong sulphuric acid (about 17) flows from a hermetic jar arranged
as aforesaid, whereby any traces of nitrous gas which may at any time
escape from the third column will be absorbed. The fourth column
being placed high enough, its liquor flows through a fifth column fixed
close to the first column, and on the same level, and similarly supplied
with gases preferably at 140° Fahrenheit, regulated in both cases by
dampers. A pipe leads the gases from the top of the fifth column into
the top of the first column. The dampers in the pipes supplying the
gases to first and fifth columns are to be adjusted, so that a draught of
atmospheric air shall be caused to enter into their bottom pieces to
eliminate all or most of the sulphurous gas from solution in the outflow-
ing liquids.
The before described improved columns are well adapted for use in
various other ways to operate or to effect changes similar to those afore-
said, with gases and liquors from sulphuric acid chambers, and also from
other manufacturing processes.
In order to obtain a reliable and well-fitting steam jet to deliver the
right proportion of high-pressure steam into the ordinary chambers or
otherwise, I employ a jet or nozzle, being conical externally, and conical
also internally, with rings traced around its extremity, so that by break-
ing or grinding off a portion, the diameter of the orifice can be increased
in a known proportion as required. It is made of unglazed earthen-
ware, or preferably of porous stoneware. At its extreme back or large

page_text: .
end its bore is contracted, and the metal steam pipe is burred out at its
end so as just to enter the back of the nozzle, into which it is pushed as
far as it will go, cement, preferably that already described, is poured
in around the steam pipe to secure it in the nozzle.
When leadwork contains coke exposed to mixed sulphurous and
nitrous gases, as, for instance, in coke columns, the leadwork of which
is well known to be rapidly eaten through and destroyed, especially
about the points of contact with the coke, I protect the lead by inter-
posing a smooth non-conductor of electricity, such as bits of broken
carboys, or stone or earthenware, as a loose lining built up (the sharp
edges being turned away from the lead). around the interior of the
vessel, paři passu, as the coke is thrown in.
In connection with chambers, I use columns with granules, prefer-
ably of the size used in the before-mentioned "fourth column," and
constructed as already described. Two columns constructed and worked
like the before-mentioned "first column," supplied with gases from the
same source as the chambers, preferably after the gas has deposited
its dust in a settling chamber through cast-iron pipes with dampers,.
and transmit it by aid of a steam blast as aforesaid into the axis of the
ordinary pipe which supplies the gases to the chambers, thus mixing
most effectually the nitrous gas and steam from the columns with the
ordinary gas entering the chambers. Through one of these columns, the
liquor from any of the chambers is passed in a slow regulated stream to
abstract and utilize all its nitrous constituents in its way to the concen-
trating apparatus. Through the other column, strong acid charged with
nitrous gas is made to pass, whereby also in some cases it is rendered fit
to return to, and be used over again in the column whence it came, which
is one like the before-named "second column," and receives the gases
from the last chamber, which are drawn through it by the steam blast
.already mentioned or otherwise. Frequently the gases from the
chambers are so constituted that the column can condense them
sufficiently without the aid of any supply of strong sulphuric acid, owing
to the powerful action of my improved columns.
The inlet pipe supplying the hot gases to the first chamber I continue
someway inwards by means of porous unglazed stoneware pipes, with
the shortest practicable bend downwards at the end. This diffuses the
gases better, besides diminishing the injurious heat in one spot at the
top of the chamber. I support a small stoneware pipe in a leaden
shoot along the top of this pipe for the gases from the curtain or side
of the chamber to a funnel in a hole in the centre of the vertical bend,
that is, so that the liquid-shall drop through the vertical axis thereof
into a shallow stoneware pan placed beneath on the floor of the

page_text: chamber. Through the curtain of the chamber, by means of pipes,
strong sulphuric acid, containing nitrous gas in solution, is passed into
the small stoneware pipe and water or weak acid is passed into the
leaden shoot, and both dip together into the said funnel, thereby mixing
the two most completely in their fall and liberating the nitrous gas in
the midst of the incoming gases and close to the liquor on the floor.
This is an alternative mode. of using the nitrous liquor in a case in which
the before-mentioned mode may be inapplicable.
I modify the concentration of the acid in evaporating pans usually
of lead; in the case of pans heated from below by making the bottoms
slant from two opposite sides down to the middle line, so as to tend to
prevent the settling of sediment except along the middle line of bottom,
under which part a support of bricks is built which keeps the heat from
it. And for the same reason, as well as to utilize lower degrees of heat
at the end of the flue, or where otherwise applicable, I expose the bare
leaden bottom without iron plate beneath, by employing circular
evaporating pans with obtusely conical or domed bottoms smooth and
free from buckles, which would weaken it, supported around the base,
and except when small also by a conical prop at the apex or centre.
The liquor within is preferably kept at a constant level, just sufficient
to cover the apex, or nearly so, continuously supplied and overflowing
by a lip drawing its overflow from the bottom. When the bottom is
liable to become furred (as by sublimed arsenic or soot), I leave a hole
in the apex, covered over just above the liquor; through the hole a brush
can be worked to clean the bottom. Over the pans I fix a covering of
boards coated with thin sheet lead beneath. Over the rectangular pans
it is roof-shaped with gable ends closed, and over the circular pans it is
conical. In both cases a space is left around the lower part for air to
enter freely, and at the summit about an equal area of aperture for the
humid air to escape. The apertures should be adjusted by trial to
obtain a maximum of evaporation. In the flues used for heating
evaporating vessels, and in flues for heating generally, I make the side
or bottom of a rigid or serrated section longitudinally instead of flat,
so as to form what may be termed a reverberatory flue. In the case of
pans heated from above I arrange the evaporating vessels in series, with
the liquor passing successively from the coldest to the hottest end, where
it flows out, as I prefer also to arrange those which are heated from
beneath I place the furnace not at the end of the series but more towards
the middle of the series, being preferably between the last and last but
one pan, so that the main draught shall not pass from the furnace over
the last one or more pans but only over the previous pans successively,
so that the one or more last pans would be heated only by oblique radia-

page_text: tion and by the eddy draught. And with a vertical contraction of the
flue from considerable height at the hotter end to the colder end, at
which part I radiate back the heat radiated from the hotter parts, and
also that which is connected in the furnace gases, and I intermingle
the gases by setting up bricks on end upon the dividing walls between
the vessels, and upon the further end wall these bricks are placed
diagonally when seen from above and with about three inches space
. between them. I introduce fresh or cooler air into the hottest pan or
pans, as by a row of holes in the end wall of the bank with deflecting
bricks inside to turn the air downwards towards and along the surface
of the liquor, or by an 'iron pipe or pipes with open-ends and a slit or
holes in their under sides fixed horizontally. through the two opposite
walls of the bank across a pan, and close above it near that end of it
(generally the cooler end), whence the surface draught sweeps to the
opposite end.
This arrangement of iron pipe is more particularly suit-
able for the pan or pans next to the furnace on either side of it and not
being the last pan.
To contract the flue, I place the pans at successively higher levels so
as to overflow from one 'to, the other with lips arranged to draw the
liquor from the bottom of the pan, and the arch is made lower also
towards the cold end, preferably by steps. I line and overlay the sides
of the hottest pans with loose fire bricks as a simpler and more certain
mode than the usual one for protecting them from being melted or
corroded above the liquor. I support the arch upon straight iron
girders acting as abutments, which are tied in by stiff arched iron girders,
preferably rolled iron of double-headed rail section spanning the roof
externally, so that the arch stands independent of those portions of the
side walls which are opposite each pan, and which I remove freely for
facilitating any repairs or renewals of the pans. There are also trans-
verse channels in the beds on which the pans rest; through these channels
any leakage can be discovered, and its position determined, and through"
these also small timbers are slid when it is desired to draw a pan out
sideways. The timbers are slit diagonally from the middle to one.end
so as to form each a pair of wedges acting vertically, which are to be
driven together so far as just to lift the vessel and bear its weight.
These timbers are then pushed out simultaneously with the pan upon
them; it can be replaced in the same manner, so that its bottom is never
chafed.
For a vessel to complete the concentration, I make the sides of it to
consist of a hollow cone, being-not an inverted cone, and the bottom of
a more obtuse hollow cone, preferably truncated near the apex by a
circle of the same material united to it, or a dome united to the sides

page_text: in one and the same circumferential base made of platinum hardened
by alloy, and not unnecessarily annealed. In forming the dome for the
bottom, it should be made thicker towards its circumference, which
portion, whether of a dome or cone, should be thicker than the sides.
The vessel is gilt-inside and more thinly outside, preferably with an
alloy of gold with a small proportion of platinum such as will make the
gold stronger, and to roll out well with the hardened platinum, and the
solder being also an alloy of gold with platinum, will prevent the gold
from readily dissolving the sheet platinum when the soldering heat is
protracted or excessive, or often repeated for repairs.
The concentrating vessel, whether of the above improved form or not,
is set on a horizontal circle, preferably. of fire brick (though one of iron
may answer the purpose better in some respects,) the fire being below
within the circle with water in the ash-pit. The products of combus-
tion rise from beneath one side of the said vessel or boiler so as to pass
around the sides of it before leaving it, whence the hot air is preferably
led to other apparatus effecting the preliminary stages of concentration
of the acid, and from which this vessel is supplied by continuous over-
flow. I fix more than one, preferably three such vessels, so arranged
side by side, and I make the liquor to flow through them all in succes-
sion by overflow from one to the other without syphons or floats, the
inflow being by a vertical tube, passing through the conical side of
which it forms part, as by soldering, trapping the gas by extending under
the surface of the liquor instead of having a separate trap in a detached
funnel. The outflow is by another similar tube, with the addition of a
short horizontal tube branching straight outwards from the vertical
tube, where it passes through the side of the vessel, and curved down-
wards at the end, preferably at only 45° inclination. This inclined
end of the tube is connected with the inflow tube of the next vessel by
a horizontal platinum pipe bent and shaped at its ends so as conveniently
to receive the outflow tube and to enter the inflow tube, forming at each
end a junction which may preferably be a loose fit, because there is
no tendency to an escape of the liquor thereat. I preferably use two
such tubes connected together in a similar manner in place of one
between any two such vessels. The two tubes being together longer
than the straight distance between their termini in the respective vessels,
so that they form together an elbow horizontally whereby their termini
can be well fitted irrespectively of the precise length of the tube. The
ends of the fixed vertical tubes in the vessel are preferably shielded
from the rise of the vapour or gas of ebullition into them by a small disc
of platinum suspended about half an inch below the end of each tube,
which is preferably dressed outwards so as to stiffen it, and form a collar

page_text: by which the disc may be attached with a wire, or in other well known
ways.
The last concentrating vessel is fitted similarly to the others, and over-
flows into the cooling apparatus, which consists preferably of a series of
closed vessels in leaden cases containing water flowing successively
through them from the coolest to the hottest. The vessels are of thin
glass or stoneware; they, as well as their leaden cases, may be con-
nected in many known ways, but preferably by glass and leaden syphons
respectively, and the concentrated acid so cooled is allowed to flow into a
store jar fitted with a cock, whence the carboys or other vessels are
filled as usual.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Petrie in the Great Seal Patent Office on the
16th February 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
PETRIE, of Woolwich, in the County of Kent, Chemist, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Sixteenth day of August, in the year of our
Lord One thousand eight hundred and sixty, in the twenty-fourth 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, my 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 AND IN APPARATUS EMPLOYED THEREIN, PARTS OF WHICH
IMPROVEMENTS ARE APPLICABLE TO THE OBTAINING OF DRAUGHT, TO THE CON-
DENSING OF GASES, AND TO THE CONSTRUCTION OF FLUES," upon the condition
(amongst others) that I, the said William Petrie, my executors 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

page_text: within six calendar months next and immediately 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 per-
formed, to be particularly described and ascertained in and by the
following statement thereof, reference being had to the Drawings here-
unto annexed, that is to say:-
My improvements relate in part to the columns previously invented
by me for effecting the requisite changes in the gases, and in part to
other apparatus used in producing and concentrating sulphuric acid.
In describing the new arrangements I shall briefly describe some of
the old parts also wliere connected with the improvements and where
they might otherwise not be exactly understood.
I use stoneware cylinders A, A, Figure 1, placed vertically in a
bottom piece B, and filled with granular material somewhat like coarse
sand, the bottom piece is contracted downwards B', B², with a curved
vertical section, and from the base B" of this contracted part a dome B'
rises so as to form the central portion of the bottom. This form has
particular advantages. At or near the bottom there is a small hori-
zontal hole B³, with a hollow tube or spigot.C ground into it for the out-
flow of liquid. Around the sides of this bottom piece are holes B", B',
one for the inlet of the gases or of atmospheric air, according to arrange-
ments herein-after described and others stoppered for other purposes.
Above the holes internally is a flange B" on which rests the outer edge
of a: horizontal ring D 1, from the inner circumference of which extends
a short hollow cylinder downwards, preferably a little below the level
of the centres of the holes B 6, B 7, &c. The aforesaid granular material
does not occupy the annular space between the exterior of this cylinder,
and the interior of the sides of the bottom piece. Above this bottom
piece I cement what. I call an intermediate piece E of the same form.
except that instead of a dome springing from its contracted lower cir-
cumference, this rests on and is cemented into a socket forming the
upper circumference of the bottom piece. Test pipes G open at both
ends and slightly inclined to the horizon, and having longitudinal slits
in the upper side, which is flattened and hollowed, extend through the
column, and are each cemented in two holes 120 degrees apart in one
of the cylinders. Samples of the liquid and gas existing at that level
in the column can be taken from the respective ends of these test pipes,
which are otherwise closed. The granules of the material filling the
column are composed of such material as compact carbon or silex
individually solid, grains of coarse sand, for instance, of a rounded
form, but a rough not polished exterior is desirable, and of sufficiently

page_text: equal size, that is, the mean diameters of as much as may be of it are to
be between two dimensions, the larger of which is not more than double
that of the smaller. The permeability to gases depends on the above
points. The positive size of the medium sized granules depends on cir-
cumstances, the grains of the granular material should be as small as
is compatible with the percolation of the liquor through it at the requisite
rate as herein-after described without any practically important restric-
tion being thereby caused to the draught of the gases through the
material beyond such an amount of restriction as would be caused by
the granular material itself without the liquor, the consequently best
size of the granules is generally between 10 and 20 of an inch. The
oxidizing and condensing power depends chiefly on this point and partly
on some of the above-named. The column is covered by a dome H, H',
and around its inclined sides are holes H³ covered by a moveable piece
of plate glass, resting on a small ring or bead surrounding the hole and
ground to a true plane; I overcome some practical difficulties by form-
ing the dome in two separate concentric parts, firstly, an external or
.circumferential part H carrying the said sight holes H 2, and the out-
let socket for the pipe of the gases H 3; and secondly a central part of
the dome with a central hole fitted with a spheric jointed funnel I; for
the inflow of liquid, with a long beak dipping into a narrow cylindric
cell J to trap the draught. The cell is pierced near its top with small
holes 1, 2, 3, 4, occupying a horizontal ring around it, and above
each hole is a notch for preserving the overflow equable all round the
cell in case of an excess of liquor passing through. The cell hangs by
a collar just below the holes, and is cemented thus to the upper circum-
ference of a hollow obtuse truncated cone K, resting its base on the
internal flange in the top of the external dome H, and having radiating
channels conveying the liquid from the small holes 1, 2, 3, 4, &c.,
respectively, and dropping it into drip channels H 4, H 4, on the flange
of the external dome, and thence into their several sets of branching.
shoots L, L, placed beneath either, resting on the surface of the granular
material or preferably on bars of plate glass placed across the inside of
-the dome and resting on an internal collar in it just above the level of
the granular material. The said shoots or troughs are so contrived as
to still further subdivide the liquid if required, and to lead it in approxi-
mately equal driblets to points equally distributed over the surface of
the granular material. The same object of dividing the liquid into equal
streams around the internal flange may be accomplished in other ways,
as by cementing the central cylindric cell J in the centre of a suitably
formed vase. with, porous_sides resting on the internal flange instead of
the channelled cone K resting thereon; in which case the small holes

page_text: in the cell J are unnecessary. In the case of smaller columns, the
channelled conical plate K fills the area of the column, and rests in the
same socket as the dome, made in a single piece in this instance, and
holes K1, K2, Figure 2 are so formed in 'the plate as to cause the liquor
to drop at points equably distributed over the granular surface while
the gases also can rise freely through these holes. I cement the various
pieces of stoneware together, where requisite, with a composition of one
measure of sulphur and about 24 of fine pure silicious sand, being as
much sand as the sulphur can take without becoming too thick to flow.
freely. This is slowly heated and stirred well in a pot until it begins
to burn brown or nearly so. If it become too stiff from being so over-
heated as to turn brown, it will recover its proper state by being stirred
while cooling.
To obtain an equable flow of liquid, where required, into the columns
or elsewhere, I use a cistern, preferably a stoneware jar, M, Figure 3,
herein-after named, the hermetic jar having a cover N, air-tight, pre-
ferably spheric fitting (patent) and fitted below with two cocks O, P,
one O entering the jar close to the other, but at a little higher level,
and has preferably a small bore to admit air inwards, and its orifice is
at a slightly higher level than that of the other, both of them dip into
a small vessel Q. When both of the cocks are open, they spontaneously
cease to discharge liquor as soon as it rises in the vessel up to the orifice
of the higher cock. Thus, at whatever rate (within a certain limit) the
liquor be drawn from the vessel, its level remains invariable. The two
cocks may be made otherwise in the form of one with two bores. The
jar is also fitted at its upper end with an inlet tube R for the liquor,
trapped by dipping into the supply tank T below; and also with a small
tube S, whereby its air can be exhausted by any of the various well
known suitable means, so as to replenish the jar with liquor when needed.
The syphon U used for withdrawing liquids from the said small vessel,
and otherwise, is of so small a bore as to clear itself of any air bubbles
as they enter, and is contracted at its inflow and turned up at its outflow
end at a somewhat higher level than its inflow, and is fixed at any
required level, according to the desired rate of flow, or to cease flowing
in a filtering cylinder standing in the vessel of liquid. The outflow of
liquid from the bottom of one column into the top of another next below
it, is not carried direct by a pipe, but is arranged so as to present con-
tinuously a portion for sampling and an automatic gauge of its rate of
flow, as follows:-The spigot of outflow dips into a narrow deep vessel
to trap the pneumatic suction; this vessel stands in a second vessel con-
nected by a contracted syphon (above described) so that the difference
of level of liquor indicates the rate of flow, while this second vessel

page_text: discharges into the top of the next column by a syphon or by an over-
How tube.
When the power of suction draught is obtained by a steam blast,
either for these columns or for chambers, or for other arrangements in
the production of sulphuric acid, or for other purposes, I obtain the
power with unusual economy of steam by directing the jet through the
axis of a cylindric tube having a conical outlet,, the largest end being
the outlet, taking care to have these rightly proportioned, namely, the
jet truly central and axial; length of cylinder from jet hole to com-
mencement of conical and 20 diameters; the conic prolongation of the
cylinder is to expand to 1 diameters in the course of its length of 10
diameters; the actual diameter of the cylindric part of the pipe should
be what is arithmetically called the fourth root of two, or about one and
a. fifth times that diameter, which would oppose as much resistance to
the steam used and the gases unitedly as the whole apparatus of columns
opposés: to the transit of the intended volume per minute of gases, the
pressure of steam should be as great as is admissible by practical.com-
venience ruled by the consideration that the consumption of fuel, ceteris
paribus, depends chiefly on the inverse square root of the pressure, so
that for instance the fuel used, if the pressure be doubled, will be
reduced, but not so much reduced as to one half. Then, these' several
conditions being provided the diameter of the steam jet nozzle should
be made such as will produce the last above-named amount of suction
force, at the same time that the gases are allowed to flow as intended
from the apparatus.
In lieu of the usual chambers and other apparatus at present con-
nected with them to convert sulphurous gas into sulphuric acid, columns
constructed as aforesaid, are arranged in the following manner :-The
sulphurous gas at a temperature preferably about 80° centigvale, is led
into the before-named intermediate piece of a first column (preferably
3 feet internal diameter and 6 feet total height) the gas passes thence
through a stoneware pipe into the intermediate piece of a second column
(preferably 3 feet diameter and 11 total height), and thence into a
third column through a stoneware pipe lengthened so as to cool the gases:
into a third column constructed without an intermediate piece (prefer-
ably 2 feet diameter and 4 feet total height) its granular material being
about three times the diameter of that of the other columns, and thence
the remaining uncondensed æriform matter is drawn out be its outlet.
pipe, terminating in a powerful means of suction draught, such as the
aforesaid steam blast. The 2nd column is supplied through a funnel at
top, as has been previously described, with a solution of nitric acid, pre-
ferably at a strength. represented by the specific gravity 1200, and

page_text: containing besides so much of sulphuric acid as may be unavoidably
formed in it in the process of working, which is now being described,
this liquid in percolating through the upper part of the column- absorbs
and partially re-oxidizes the greater part of the nitrous fumes which
are become nearly free from sulphurous gas by. its.conversion into
sulphuric acid in the lower part of this column; this latter result is
effected by the said liquor as it arrives further down the column, where
the consequent formation of sulphuric acid principally takes place, this
liquor then on passing downwards below the intermediate piece of the
column is deprived of much of the nitrous and sulphurous gases which
it may hold merely in solution. This is effected by the action of atmo-
spheric air entering at small holes in the stoppers of the bottom piece
of the column; this ingress of air must be regulated so as just to effect
this, whereby the loss of these gases will be prevented as far as may be
during the return of the liquor to the hermetic jar, and when the liquor
passes thence again into the second column, their evolution and transit
into the third column will also be thus avoided. The liquor in flowing
out of the second.column passes into a stoneware vessel, where a glass
syphon is arranged as already described, and is regulated to draw part
of it into the first column placed sufficiently low while the rest overflows
by a tube or a lip into a covered jar or cistern whence it is occasionally
raised into the hermetic jar fitted and working as already described,
so as to return the liquor into the 2nd column by a continuous circula-
tion. The liquor which percolates. through the first column loses its
nitric acid, &c., and flows out as pure sulphuric acid (if the materials
used be pure) into a receiving vessel or into a concentrating apparatus.
Into the third-column a regulated and comparatively small-streamlet, of
some liquor or saline solution which absorbs nitrous gases, preferably
I employ strong sulphuric acid about 17 specific gravity, flows from a
second herinetic jar arranged as aforesaid, whereby traces of nitrous
gas, which may escape from the 2nd column will be absorbed. The
3rd column being placed high enough, the liquor flows from it through
a fourth column (preferably 1 feet diameter, and of the same vertical
dimensions and construction as the first column, and fixed close by the
side of it and on the same level) similarly supplied with gases regulated
in both cases by dampers, and a pipe leads the gases from the top of the
fourth column into the top of the first column. The strong sulphuric
acid loses for the most part its nitrous gases in passing through the
fourth column, and flows out into a jar or cistern, whence it is from time
to time raised and returned into the before-named second hermetic jar
which supplies the 3rd column; or, if the acid from the fourth column

page_text: be not of the proper strength and quality, it is first to be made so, and
then returned into the second hermetic jar.
Adjustments needed for working.-The stock of nitric liquor circulat-
ing continuously to and from the second column is to be replenished in
the said lower jar with water, either from time to time, or continuously
by a cock, to balance the increase of strength owing to the condensation
of nitrous and sulphurous gases coming from the first column and to
balance the loss of volume owing to what passes continuously into the
first column, and to maintain the strongly nitrous constitution of this
liquid nitric acid or a solution of nitrate of soda is added in the same
manner, when necessary, or else nitrous gas is added in the usual manner
to the sulphurous gas before it enters the columns. The draught of
suction is to be regulated so that it shall draw the sulphurous gas into
the first and fourth columns at such rate as to become nearly entirely
absorbed by the time the gases approach the upper part of the second
column, while thus the free nitrous gas will be for the most part changed
into liquid nitric acid, or at least absorbed by solution during the
remainder of its ascent through the 2nd column. The dampers in the
pipes supplying the gases to first and fourth columns are to be adjusted,
so that a sufficient inward draught of atmospheric air shall be caused
into their bottom pieces to eliminate all or most of the sulphurous gas
from solution in the outflowing liquids. The flow from the hermetic jar,
supplying the second column need not be greater than enough to secure
that the liquor flowing through the second column shall be nearly
equally rich in nitrogeneous compounds at every part of its height. The
liquid entering the first column should be regulated to just such rate of
flow that it shall become sulphuric acid entirely deprived of its nitro-
geneous compounds by passing through this column.
The before described improved columns and other apparatus are well
adapted for use in various other ways to operate or to effect changes
similar to those aforesaid with gases and liquors from sulphuric acid
chambers and also from other manufacturing processes.
For securing a reliable and well fitting steam jet to deliver steam
with the full velocity due to its high pressure into the ordinary chambers
Z, Z, or otherwise without variation in the quantity by wear or rust of
the orifice in a short time as with lead or iron jets, I employ a jet V, as
shown in Figure 4, being conical externally and internally, with rings
W traced around its extremity, so that by nipping off or grinding off a
portion the diameter of the orifice can be increased in a known propor-
tion, as required; it is made of unglazed earthenware, preferably porous
stoneware at its back or large end; its bore is contracted by an internal
collar V 1, and the metal steam pipe X, as of lead or iron is burred out

page_text: at its end, so as just to enter the hole or internal collar, into which it is
pushed as far as it will go, and cement Y preferably that already,
described, or plain sulphur is poured in around the steam pipe. Where
there is lead work containing coke exposed to mixed sulphurous and
nitrous gases, as in coke columns or scrubbers, the lead work of which
is well known to be rapidly eaten through and destroyed, especially
about the points of contact with the coke, I protect the lead by inter-
posing a smooth non-conductor of electricity, such as bits of broken
carboys or stoneware, so as to form a loose lining (with the sharp edges
turned away from the lead) built up around the interior of the vessel,
pari passu, as the coke is thrown in.
In connection with chambers I use columns with granules preferably
of the size used in the fourth column before mentioned, and constructed
as already described, two columns constructed and worked like the
before mentioned first column supplied with gases from the same source
as the chambers, preferably after the gas has deposited its dust in a
settling chamber, the gas entering the columns warm through cast iron
pipes with dampers, and transmitting it by aid of a steam blast as afore-
said from the top of the columns into the access of the ordinary pipe,
which supplies the rest of the gases to the chambers, thus mixing most
effectually the nitrous gas and steam from the columns with the ordinary
gas entering the chambers. Through one of these columns the liquor
from any of the chambers is passed in a slow regulated stream to abstract
and utilize all its nitrous constituents in its way to the concentrating
apparatus. Through the other column a liquor is made to pass, which
absorbs nitrous gas, such as strong sulphuric acid, this liquor already
charged with nitrous gas surrenders it to the chamber by passing through
this column, and the liquor itself becomes thereby nearly or quite fit to
be returned, and used over again in the column whence it came, which
is constructed as already herein described, only without an intermediate.
piece; this column receives the gases from the last chamber; they are
drawn through it by the steam blast already mentioned or otherwise.
Frequently the gases from the chambers are so constituted that this last-
named column can condense them sufficiently without the aid of any
supply of strong sulphuric acid owing to the powerful action of my
improved columns.
As an alternative mode of using the nitrous liquor from any source I
make the following arrangement:-The inlet pipe supplying hot gases
to the first chamber I continue some way inwards by means of porous
unglazed stoneware pipes with the shortest possible bend downwards
at its end or vent; this diffuses the gases better, besides diminishing
the injurious heat in one spot, at the top of the chamber; I support a

page_text: small stoneware pipe in a leaden shoot along the top of this pipe for
.the gases from the curtain or side of the chamber to a funnel in a hole
in the centre of the vertical bend already last named; that is, so that the
liquid should drop through the vertical axis of the bend at the end or
vent without touching the sides of the pipe into a shallow stoneware
-pan placed beneath on the floor of the chamber. Through the curtain
of the chamber by means of pipes strong sulphuric acid containing
nitrous gases in solution is passed into the small stoneware pipe, and
water or weak acid is passed into the leaden shoot, and. both dipped
together, into the said funnel, thereby mixing the two most completely
in their fall and liberating nitrous gas in the midst of the incoming gases,
and close to the liquor on the floor of the chamber.
The concentration of the acid in evaporating pans usually of lead I
modify in the case of pans heated from below, Figure 5) by making
the bottoms A, A, slant from two opposite sides down to the middle
line, so as to tend to prevent settling of sediment except along the
middle line of bottom, under which part a support of bricks B is built,
which keeps the heat from it; and for the same reason, as well as to
utilize low degrees of lieat at the ends of the flue, or where otherwise
applicable, I expose the bare leaden bottom, without iron plate beneath,
by employing circular evaporating pans F, F, Figure 7, with obtusely
conical or else domed bottoms, smooth and free from buckles, which
would weaken it, supported around the base, as, for instance, on an
iron ring, and, except when small, also by a conical prop G at the apex
or centre. The liquor within is preferably kept at a constant level, just
sufficient to cover the apex or nearly so, continuously supplied and over-
flowing by a lip, so arranged and constructed as to draw its overflow
from the bottom of the pan. When the bottom is liable to be furred
(as by sublimed arsenic or by soot), I leave a hole in the apex, covered
over, just above the liquor; through the hole a brush can be worked
to clean the bottom. Over the pans I fix a covering of boards, coated
with thin sheet lead beneath; over the rectangular pans it is roof shape
C, C, with the gable ends closed, and over the rectangular pans it is
conical H, H. In both cases a space is left around the lower part for
air to enter freely. I prefer to effect this by making the lower edge of
the boarding to terminate at the same level as the top of the pan, but
not to extend quite so far as the edge of the pan from the centre, and at
the summit about an equal area of aperture for the humid air to escape.
The apertures should be adjusted in size by trial to obtain a maximum
of evaporation. This plan- I consider to be much more advantageous
than 'the usual modes of covering evaporating pans, or of leaving them

page_text: uncovered. In the flues used for heating these and platinum evaporating
vessels and steam boilers, and for such purposes, I make the side or
bottom opposite to the surface of the vessel not flat but of a ridged or
serrated section longitudinally D, D, Figure 6, as by the projecting
edges of bricks placed at an angle for the purpose of better radiating
the heat and of mingling the hot air and of deflecting it against E, the
side to be heated. The dust collects in these transverse channels, but
provision is to be made in the brickwork for opening their ends severally
to rake them occasionally.
In the case of pans heated from above, I arrange the evaporating
vessels in series with the liquor passing successively from the coldest to
the hottest end, where it flows out; as I prefer also to arrange those
which are heated from beneath. I place the furnace not at the end,
but between the 4th and 5th pans M and N, Figure 8, or even between
the 3 and 4 pans, where there are 5, so that the main draught shall
pass from the furnace only to over the 4th or 3rd and 2nd and 1st pans
M, L, K, J, and not to over the 5th N, or 4th and 5th, but this part
is heated only by oblique radiation and by the eddy draught; and I make
a contraction of the flue measuring vertically; it is contracted from
considerable height at the hotter end to the colder end, with checks
R, R, across the draught at this end, as described a little further on.
The essential features of this combination of arrangements consist in
imparting heat at the greatest rate to the liquor at the middle portion
of the series, not necessarily to raise the temperature there above that
at the end of the series, for the heat is rendered latent by the evapora-
tion from the liquor, while the outflow end receives the heat at a less
rate, so as to evaporate its watery part more gradually; and in imparting
the heat which remains in these furnace gases as they come toward the
cool end as completely as may be to the liquor there, which being
successively cooler according as it is nearer the end, is capable of
absorbing and utilizing the successively lower degrees of heat remaining
in the gases from the furnace. I introduce fresh air to the hottest pan
or pans, as by a row of holes S in the end wall of the bank, with
deflecting bricks T inside to turn the air downwards to the surface of
the liquor, and by an iron pipe or pipes U, U, with open ends and a.
slit or holes in the under sides, fixed horizontally through the bank
just above a pan, near that end of it (generally the cooler end) whence
the draught sweeps to the opposite end by an eddy current. The ingress
of air at these points must be regulated so as not to injure the draught
of the fire. This use of pipes is more particularly suitable for the pan
next the furnace toward the inflow end of the bank; by such arrange-

page_text: ments the air sweeps along the hot surface of the liquor, which is mean-
while heated by radiation from above; this air containing less moisture,
and being cooler than that already in the flue, keeps next the furnace,
and displaces that which has already absorbed moisture and become
warmer, which otherwise would not be so effectually or quickly displaced
by the other air, which coming from the furnace is more buoyant. In
this way I promote the evaporation of the watery part without increasing.
the temperature, which in the case of these pans with strongest liquor
would waste the acid and injure the pans. To contract the flue I place
the vessels J, K, L, M, at successively lower levels, so as to overflow
from one to the other, and the crown of the arch rises from the cold
end to the hot end. The vessels have lips J', K', L', arranged to draw
the liquor from the bottom of the vessels and from M to N, where the
fire intervenes the liquor is carried by means of a syphon at one-side
not shewn in the. Drawing. I line and overlay the sides of the hottest
vessels with loose fire-bricks, as a simpler and more certain mode than
the usual one for protecting them from being melted or corroded above
the liquor. At the cool end of the flue I reflect back the heat radiated
from the hotter parts, and also that which is connected from the furnace
gases;. and I intermingle the gases by setting up bricks R on end upon
the dividing walls X, X, between the vessels and upon the furthest end
wall. These bricks are placed diagonally as seen from above, and with
about 3 inches space between them. I support the arch upon straight
iron girders V, V, Figures 8 and 9, acting as abutments, which are tied
in by stiff arched iron girders of the double-headed rail section W, W,
spanning the roof or arch externally, so that the arch stands indepen-
dent of those portions of the side walls Y, Y, which are opposite each
vessel, and which I remove freely to facilitate any repairs or renewals
of the vessels. There are also transverse channels Z, Z, in the beds
on which the vessels rest; through these any leakage can be at once
discovered and its position determined; and through these also, when
needed. small timbers are slid, these having been slid diagonally from
the middle to one end, so that they can be forced together as wedges
to take.the weight of the vessel when it is desired to draw it out, which
is then done by pushing those timbers out with it upon them, and it is
replaced in the same manner, so that its bottom is never chafed against
the brickwork.
For a vessel to complete the concentration, I make it in the form of
two hollow cones, .A, A, and B, B, Figure 10, and partly seen. in
Figure 11, these cones being united in one and the same circumferential
base. One truncated forms the sides, and the other of thicker material

page_text: and more obtuse, preferably truncated near its apex by a plane circle C
united to it, forms the bottom. The vessel is made of platinum,
hardened by alloy and not unnecessarily annealed; it is gilt inside, and
more thinly outside, preferably with an alloy of gold with a small portion
of platinum, such as will make it stronger and to roll out well with the
hardened platinum, and the solder, being also an alloy of gold with
platinum, will prevent the gold from so readily dissolving the sheet.
platinum, when the soldering heat is protracted, or excessive, or often
repeated for repairs. The vessel is set on a circle F, Figures 10, 11,
and 12, of fire-brick (being generally preferable to one of iron), the
fire being below within the circle with water in the ash-pit. The
products of combustion rise at one side G, Figures 10 and 12, of the
boiler or vessels, so as to pass around the sides of it above F before
leaving it, whence the hot air is preferably led to other apparatus,
effecting the preliminary stages of concentration of the acid, and from
which this vessel is supplied by a continuous overflow.
I fix more than one preferably 3 such vessels so arranged side by side...
Figure 11, and I make the liquor to flow through them all in succession
by overflow from one to the other without syphons or floats, which cause
complication and need attention. The inflow is by a vertical tube H
passing through the conical side of the vessel, of which it forms part,
as by soldering; this tube traps the gas by extending under the surface
of the liquor instead of having a separate trap in a detached funnel.
The outflow is by another similar tube I, with the addition of a short
horizontal branch tube J, curved downwards at the end, preferably
at only 45 degrees inclination; this is connected with the inflow tube
of the next vessel by a horizontal platinum pipe K, bent and shaped at
its ends so as conveniently to receive the outflow tube J and to enter
the next inflow tube. The tube K is preferably made in two parts, K
and K', Figure 11, united by an upright slip joint, in the same manner
as its extremities are united to the vessels, and forming a horizontal
elbow at the union of the two parts, so that no care is necessary as to
precise length of this tube, or of the distance between the two vessels
which it unites. The bottoms of the inlet and outlet tubes H and I are
protected by a small shield L adapted to them, so as to prevent bubbles
of sulphuric acid vapour from casually rising into these tubes. These
forms and arrangements effect considerable economy over those
commonly adopted in the amount of platinum required and in its repairs
subsequently. I consider this plan to effect also more economy in fuel
than existing plans which I might employ. These arrangements also
reduce the serious risk of injury in case of neglect on the part of the

page_text: workman conducting the process, and the produce. is more easily
brought out at full strength. The last concentrating vessel being fitted
similarly to the others, overflows into the cooling apparatus, which
consists of a series of closed vessels M, M, in leaden cases N, N, con-
taining water, flowing successively through them from the coolest, to
the hottest. The vessels are of thin glass or stoneware; they as well as
their leaden cases may be connected in anyways, but preferably by
glass syphons; in the case of the acid the syphons should have their
respective limbs so proportioned as to draw it from the lower part of
one vessel, and to emit it at the upper part of the next vessel; and in
the case of the water they should act vice versa.
And having now described the nature of my said improvements, and
the manner in which the same are to be performed, I declare that I
claim,―
Firstly, the form of the base or bottom piece, as described, for such
columns, also the particular arrangement of my intermediate piece, so
called, in the several columns, in the manner described, and for the
said purpose in the said combination of columns thereafter described.
of eliminating by atmospheric air and restoring to the part of the column
next above the intermediate piece the gases dissolved in, but not com-
bined chemically with the liquor; also the supporting of the internal
rings by internal flanges, forming parts of the bottom piece and inter-
mediate piece respectively; also the employment of test pipes as
described, and all and every of these arrangements.
Secondly, the formation of the dome or cover in two concentric parts
(H' and H³, Figure 1), so that access can be had to the interior by
removing the small central part without disturbing the rest of it, and
the adjustments of the parts for distributing the liquor, or other arrange-
ments dependent on the dome; also the following combination of parts
herein-before illustrated in and about the dome for distributing the
liquor uniformly over the top of the material in the column, namely.
the combination of a vessel or cell traping the inflow end of the tube
or funnel, and so formed as to drop its liquor from a number of places
around its circumference to the several portions of an internal flange in
the fixed circumferential portion H' of the dome; these several portions
of the flange being so slanted as to shed the liquor into shoots or troughs
so placed beneath as to distribute the liquor to equidistant points over
the surface of the granular material; also the modification of this in
smaller columns, by forming holes at the required points in a conical
plate, so as to drop the liquid direct upon the granular material, the
gases rising through the holes also, and the plate covering the whole area

page_text: or the column, or nearly so, and supporting or iorming part of the central
cell or vessel above named.
Thirdly, the hermetic jar or cistern for causing an equable flow of
liquor where required in the manufacture of sulphuric acid or for other
purposes to which this Patent refers, the same consisting of a vessel
with an air-tight cover at top, and fitted with two cocks having their
orifices at different levels and dipping into the liquid, so as to act as
described herein.
.
Fourthly, the improved means of obtaining draught by a steam blast.
consisting of a jet working through the axis of a tube, having its form
and proportions and actual dimensions arranged in each instance as
described, or so far approximating thereto as to secure the greater part
of the economy of steam due thereto.
Fifthly, for leaden chambers or lobbies working in any ordinary
manner I claim the application of the other improved steam jet (not the
steam blast last named), combining the following peculiarities:-It is
composed of the usual metal pipe, secured in the manner described, in
a nozzle of stoneware or earthenware, conical externally and internally
to the extreme orifice; also the protection of leadwork containing coke
with sulphurous and nitrous gases, by employing a smooth material,
being a non-conductor of electricity, to keep the coke out of contact
with the lead; each of these.
Sixthly, the employment of slanting or inclined bottoms in leaden
evaporating vessels, as described, the inclination being from two
opposite sides towards the middle line, so as to aid in preventing the
accumulation of sediment thereon, except on the. middle line of bottom,
which is more protected from heat; also the reverberatory form of flues,
as described; also the employment of conical bottoms in leaden
evaporating vessels, so as to utilize the heat more perfectly by dispensing
with the continuous support of an iron plate or grating, the apex of the
cone being near to or above the surface of the liquor; also the whole
at the apex of the before said cone, for the purpose of cleaning the under
side of the bottom of the vessel; also the use of inclined covers, sloping,
as described, from the middle over the evaporating pans used in manu-
facturing sulphuric acid, with openings of suitable size at top and around
the lower part, so as to promote circulation of the air for better
evaporation, at the same time that the heat is economised by being
radiated back into the liquor as it is in the case of coverings, flat, or
otherwise, sometimes used, and which I do not claim. I claim all and
every of the above.
Seventhly, the improved reverberatory evaporating bank, being the

page_text: combination of a series of evaporators, having the liquor passing succes-
sively from the colder to the hotter end where it flows out, with the
intermediate position of the furnace between two evaporators near the
hottest end, but having the draught only in one direction, and with
much vertical contraction of the flue towards the colder end, the essential
features of this arrangement consisting as herein-before stated; also the
introduction of fresh air to the hottest pan or pans of a reverberatory
concentrating apparatus, by the means and for the purpose herein-before
described; also the supporting of the arch or roof of the concentrating
furnace upon girders, supported independently of those portions of the.
side walls, which, by being removed when desired, will allow of the
evaporating pans being drawn out and returned sideways for renewal
or repair; and all and every of them.
Eighthly, the construction of boilers to complete the concentration of
sulphuric acid, having the shape and material of the sides and bottom,
such as are herein-before described, also the combination of certain
pȧrts and arrangements of apparatus for the concentration of sulphuric
acid in metallic vessels, preferably of platinum, being substantially
such as are described in the words referring to the letters H, I, J, K,
Figure 10.
WILLIAM PETRIE. (L.S.)