IMPROVEMENTS IN THE MEANS AND APPARATUS FOR DEOXIDATING METALLIC ORES, OXIDES, AND SULPHATES, WHICH IMPROVEMENTS ARE EQUALLY APPLICABLE TO THE COKING, CHARRING,' AND DESTRUCTIVE DISTILLATION OF ANY SOLID ORGANIC MATTER, TO THE CALCINING OF METALLIC ORES, AND TO THE PRODUCTION OF CARBONIC OXIDE FLAME
Year: 1875

page_text: LETTERS PATENT to William Alexander Lyttle, of The Grove,
Hammersmith, in the County of Middlesex, Civil Engineer, and
Fellow of the Chemical Society, for the Invention of "IMPROVEMENTS
IN THE MEANS AND APPARATUS FOR DEOXIDATING METALLIC ORES, OXIDES,
AND SULPHATES, WHICH IMPROVEMENTS ARE EQUALLY APPLICABLE TO THE
COKING, CHARRING,' AND DESTRUCTIVE DISTILLATION OF ANY SOLID ORGANIC
MATTER, TO THE CALCINING OF METALLIC ORES, AND TO THE PRODUCTION OF
CARBONIC OXIDE FLAME."
ealed the 9th December 1875, and dated the 15th October 1875.
PROVISIONAL SPECIFICATION left by the said William Alexander
Lyttle at the Office of the Commissioners of Patents, with his
Petition, on the 15th October 1875.
I, WILLIAM ALEXANDER LYTTLE, of The Grove, Hammersmith, in
the County of Middlesex, Civil Engineer, and Fellow of the Chemical
Society, do hereby declare the nature of the said Invention for "IMPROVE-
HENTS IN THE MEANS AND APPARATUS FOR DEOXIDATING METALLIC ORES, OXIDES,
AND SULPHATES, WHICH IMPROVEMENTS ARE EQUALLY APPLICABLE TO THE COKING,
A

page_text: CHARRING, AND DESTRUCTIVE DISTILLATION OF ANY SOLID ORGANIC MATTER, TO
THE CALCINING OF METALLIC ORES, AND TO THE PRODUCTION OF CARBONIC OXIDE
FLAME," to be as follows:-
This process consists chiefly in the use of a peculiar hollow wall,
consisting of two thin adjacent and parallel partitions, between which
the material to be charred, deoxidated, or otherwise treated, as hercin-
after described, is placed by being continuously charged in from the top,
and this hollow wall, in addition to its other applications, is intended to
act as a substitute for retorts in the deoxidation of metallic ores, oxides,
and sulphates; also in the production or revival of animal or other
charcoal, and in the manufacture of gas for illuminating and other
purposes. A slight modification of this hollow wall arrangement also
furnishes a convenient means of generating carbonic oxide flame.
A long narrow rectangular fire-brick chamber is divided vertically and
longitudinally into two distinct sections by means of a hollow wall
parallel to the side walls, and carried or joined into the two narrow end
walls of the brick chamber. This hollow wall is made of two thin
partitions which are longitudinally parallel, but lean towards each other
at a slight angle from the bottom uniformly upwards to the top, the
object of such inclination being that anything filling this hollow wall
shall have a tendency to make its way by gravitation downwards. These
thin partitions forming the hollow wall may either be made air-tight by
plates of metal or fire-clay for the radiation of heat only; or they may
in certain cases be constructed of openwork material in the following
manner: The partitions may be made of wire web with strong transverse
bars or stays; or they may consist of perforated metal plates or sheets;
or of perforated tiles like those which form the floors of kilns for drying
grain, such plates, sheets, or tiles being similarly stayed. The most
durable as well as economical method of forming such openwork
partitions is to construct them of cast iron or fire-clay bars, like fire-
bars, set horizontally in vertical pillars in such a way that they shall
present the same appearance as a Venetian window blind, or the
ventilating windows of the cooler of a brewery. These bars or plates
may be set at such an angle of inclination to the vertical plane in which
they stand that the upper edge of each shall project outwards, and the
lower edge inwards, the lower edge of each bar being overlapped in this
desired distance by the plate which stands next beneath it.
In this overlap however there must be no close contact, but, on the
way
to any

page_text: contrary, as free a passage for gas or flame as may be found possible
without allowing the escape of the solid contents. This openwork
arrangement is specially applicable to the deoxidation of ore, as here-
after described, when it is desired to utilize the carbonic oxide of the
flame, and also to the recharring of powdered animal charcoal after
exhaustion by use as a filtering agent. On one side of this hollow wall
the chamber may be supplied with a carbonic oxide or non-oxidizing
flame generated by a blast furnace at its bottom in any ordinary or
desired manner, and this flame may be forced through the material
under treatment inside the hollow wall by generating it under a suitable
pressure of blast. The other or second side of the fire-brick chamber,
which must be perfectly air-tight, may communicate with a flue for the
removal of the escaping gases and vapours to be utilized in any desired
way; or these gases may be caused to pass from the second half of this
chamber, after going through the hollow wall, directly upward to the
corresponding half of a similar chamber overhead, up through which the
hollow wall shall be continuously carried. The escaping gases should
have no egress from this half of the upper chamber, except through the
charge of material under treatment in the hollow wall, and this matter
would thus be made to absorb the remaining heat of the escaping gases.
The material thus heated in the hollow wall will subside periodically to
the hottest or bottom chamber as the charred or deoxidized product is
withdrawn from the bottom of the hollow wall.
The sides of the hollow wall should be made impervious at the line
of the floor dividing the upper and lower chambers for such a distance
as will prevent the direct passage of the flame at that point upward
vertically through the hollow wall. The reason of this result from using
the short line of impervious sides is that a passage transversely through
the hollow wall and thence to the upper chamber as described will then
be the course of least resistance.
Any number of chambers above each other, with one continuous
hollow wall constructed as described, can be thus arranged for the
utilization of the whole of the heat in the escaping gases by forcing
them zig-zag, as stated above, from chamber to chamber through the
material contained in the hollow wall.
The material under treatment should be charged into the top of the
hollow wall after each withdrawal of charred or deoxidized products
from the bottom.

page_text: The bottom of the hollow wall may be closed by rotary fire-bars or
rotating plates which, when made to turn on their axis to one side, shall
wholly close the bottom, and when turned in the reverse direction shall,
like the laths of a Venetian window blind, present open spaces with
the planes of the plates or fire-bars standing parallel and vertical.
The horizontal plates herein-after described, with axles passing
through the ends of the chamber will answer the same purpose, but
any arrangement of ordinary sliding plate or other convenient bottom
may also be employed. By this means it is possible to discharge any
desired quantity of the finished contents of the hollow wall into trucks
standing underneath, in a space wholly closed against the admission of
air until the bottom of the hollow wall is closed. The latter precaution
is required only when it is necessary to avoid exposing the finished
product to the atmosphere; but if the hollow wall is carried down as a
cooler with sheet or plate iron sides below the furnace level no such
precaution is needed, because the product will not then be withdrawn in
a red hot state. When reduced or deoxidized material which may be
readily liable to re-oxidation is thus withdrawn in a hot state it is
desirable to cover it rapidly with powdered peat or other charcoal in a
red hot or cold state. The fine dust of coal will answer the same pur-
pose as the charcoal. One half of the chamber thus divided by the
hollow wall may have a furnace at its bottom, or communicating with
it through a suitable opening or line of holes provided in the side wall
of the chamber for the admission of the flame from a furnace con-
structed outside. This outside furnace had better be adapted to generate
a carbonic oxide flame only, and provision should be made by tuyerès
set in the apertures through which the flame enters the chamber, for
the complete or partial combustion of the carbonic oxide by a hot or
cold blast when that gas is not needed, as the sole reducing agent in my
application of this furnace to the deoxidation of ores and other sub-
stances. It is not necessary however in some applications of this hollow
wall apparatus that the charring or reducing flame should pass through
the material under treatment, because if a furnace flame is made to
act on both sides of the hollow wall the same effect is produced, and in
that case the higher the chamber is with the hollow wall, as described,
the greater will be the efficiency of the heat. The latter object will be
still better attained by providing projecting shelves of iron, fire-clay,
or other refractory material, which shall reach out from the side wall

page_text: of the chamber to the hollow wall, so as to completely close that side
space with a floor except at one end. The next higher floor or shelf
should have its opening at the opposite end, and so on, the object being
to impart a long "zig-zag " journey to the flame on its way upwards.
When the flame is not forced through the material under treatment in
the hollow wall the partitions or sides of this wall need not necessarily
be made of openwork, as herein-before described, but may consist of
impervious solid plates of metal or other material of a refractory nature.
The end walls of this fire-brick chamber into which the hollow wall
abuts, may be furnished with small holes provided with air-tight
traps, through which the shelves for giving a "zig-zag" course to the
flame may be periodically cleared of dust, one by one downwards, or
out through the holes in the end walls by a hoe or brush pusbed in for
that purpose.
Horizontal plates of iron fitted to strong spindles or
axles may be placed inside the hollow wall with the axles projecting at
one or both ends, through close fitting cast-iron collars, with a crank or
other gearing outside upon the end of the axle, in order that by moving
such crank a rotary motion may be given, when needful, to the hori-
zontal iron plates. These plates should act like throttle valves or
flue dampers by forming a diaphragm, almost cutting off the vertical
continuity of the space in the hollow wall when set horizontally, and
presenting no obstruction when turned forty-five degrees to either side,
so that the plane of the plate may be vertical.
Instead of one plate two or more narrow ones may be set side by side,
and their joint action will have the same effect. By this means a high
chamber can be used for the charring of brittle materials, like exhausted
animal charcoal from sugar works, without such a dead pressure on that
material which has reached the bottom of the hollow wall, and a move-
ment of these plates will prevent any stoppage or jamming of the
contents.
In order to use this peculiar heating apparatus for the deoxidation of
metallic ores or oxides, or of earthy sulphates in order to form sulphides,
the hollow wall may be made the means of effecting the desired opera-
tion, either wholly or partially, by the carbonic oxide of the furnace
flame, or wholly by heat radiated from the flame through the sides of
the hollow wall, powdered carbonaceous matter incorporated with the
powdered substance under treatment being in the latter case the only
reducing agent.

page_text: When carbonic oxide alone is employed as the reducing agent the
sides of the hollow wall must always be made of openwork as described,
so as to give entrance to the gas, which may be forced through the
charge of broken ore if desired. Again, the ore, metallic oxide, or
inorganic sulphate, requiring deoxidation may be crushed and mixed
with powdered carbon, and if a carbonic oxide flame is employed, it
will act as an auxiliary by diffusion to the intermixed solid carbon.
When the charge in the hollow wall consists of crushed ore or
inorganic sulphate and carbonaceous matter the greatest economy is
attained by making its sides almost or wholly air-tight, with only a
narrow space between them for the charge of ore or sulphate and car-
bonaceous matter, the heat being radiated through iron or fire-clay side
plates from a perfectly consumed flame in which all the carbon has
been burned into carbonic anhydride.
The same principles of applying heat by means of the aforesaid hollow
wall process apply equally to the charring or coking of bones or the re-
charring of animal charcoal which has become exhausted through use as
a filter, or to the charring or coking of any other organic substance,
mineral or otherwise. Openings are provided into the ends of the
hollow wall by means of holes through the end wall of the brick
chamber, against which the end of the hollow wall abuts, and the gases
and vapours generated within the hollow wall can be drawn off by means
of branch pipes leading from these holes into a flue or main pipe
standing vertically against the end wall. This is the arrangement which
answers for the coking of coal, and the manufacture of illuminating gas
therefrom, and for the distillation of hydrocarbon oil under this process.
Holes closed air-tight by trap doors may also be provided opening at
various points into the ends of the hollow wall, through which iron
bars can be inserted when necessary for the purpose of removing
obstructions.
When the material coked is very liable to glue together it is well to
interstratify it with alternate layers consisting of either irregular lumps
of refractory material or short lengths of cast-iron piping laid longi-
tudinally, so as to provide a horizontal drainage for the gases and
vapours to the openings at the end or ends of the hollow wall which
lead into the aforesaid vertical main pipe. When bituminous coal is
thus coked the aforesaid horizontal plates cannot be employed within
the hollow wall.

page_text: When the hollow wall is long in a narrow rectangular fire-chamber,
this form being the most economical, the top may be provided with a
series of air tight hoppers, through which the charge can be introduced,
and the bottom of the hollow wall may be carried down below the
hottest zone to any desired depth as a cooler of the charge before it is
withdrawn.
When coal gas is manufactured by means of this apparatus, or when
animal or other charcoal is produced or revived by the aforesaid coking,
the coked material may be allowed to subside into a tank of water
which acts as a seal to close the bottom of the hollow wall. The same
use of a water bottom is equally available when any mineral sulphate,
such as baric sulphate or calcic sulphate, is reduced to sulphide by
means of intermixed carbon in the hollow wall, as described.
Metallic ores or oxides of metals, with or without admixture of
carbon, can be reduced so as to give up the metal in a pulverulent or
volatilized state, according to the nature of the ore employed. When
zinc or other volatile metal is thus produced the sublimed metal will be
received in the vertical main pipe, herein-before described as the receiver
of gases and vapours, and the same interstratifying of the charge of ore
with layers of refractory lumps or short pieces of piping should be
employed in order to give free egress to the metal. The main or receiver
must in that case be made of larger diameter, with means of access for
the removal of the deposited metal. Iron ore thus reduced may be
subjected to cementation with intermixed redundant carbon, either in
the hollow wall or after removal therefrom, precisely as described in the
Specification of my Letters Patent of 12th January 1875, No. 105, and
entitled "Improvements in the Means and Apparatus for Producing or
Manufacturing Iron, Steel, and other Metals." The reduced iron or
powdered blister steel thus produced may be worked into "blooms," or
melted into ingots of cast steel, as described in the Specification of that
Patent, and the same aforesaid hollow wall process may be employed for
the production of copper as a reduced metallic powder. When highly
fusible metals are thus deoxidized, such as lead or tin, the resulting
metal will be found in drops, flakes, and irregular lumps, or fragments
amongst the redundant carbon, and the "gangue" in the bottom of the
hollow wall.
The winnowing machine may be emploved for the separation of the

page_text: my aforesaid Patent No. 105, or washing by water may be used instead,
especially when the charge containing the reduced lead or tin is
cooled by water, as above described in the case of coke or animal
charcoal.
In order to take advantage of greater height, whilst still preserving
the aforesaid widening taper outwards in the sides of the hollow wall,
and yet preventing too great thickness of the charge at the bottom of
the said wall, the wall may be carried undivided with the required taper
downwards to half its height or any other desired point, and at that
point it may be split, with an acute angle of divergence, into two hollow
walls so as to present a cross section like an inverted letter Y, the
bottom of that letter being the top of the wall. A furnace flame may
be made to circulate in the angle between the lower hollow branches of
this divided hollow wall, as already described.
This apparatus and method of applying heat is available not only for
charring or deoxidizing with direct contact of a carbonic oxide flame,
as already described, but also to every purpose of coking, deoxidizing,
or destructive distillation in which a retort is or can be now used. It
is specially applicable to the distillation of hydrocarbon oil from any
mineral or suitable solid matter, and to the production illuminating
or hydrocarbon gas.
When it is not deemed desirable to force a carbonic oxide flame
through the matter under treatment in the hollow wall the principle of
that hollow wall arrangement will be equally observed by lining the
outside walls of the aforesaid brick chamber with an inner partition or ;
facing made of iron plates or other suitable material placed and firmly
stayed at such distance from the brick or other outer wall of the
chamber as may be found sufficient to give passage downwards to the
material under treatment. This plating may either be made to incline
outward from the wall gradually from the top downward, or it may be 3
made perpendicular and parallel to the outer wall. Holes may be
provided in the outer wall, through which, when uncovered, iron bars
can be inserted in order to remove any accidental obstruction. Two
outer hollow walls made thus against the solid walls of the chamber
may also be employed in conjunction with the inner hollow wall, a
which divides the chamber into two parts, as herein-before described.
The hollow wall arrangement herein-before described is in all respects
available for the destructive distillation of bituminous coal or peat, and

page_text: for the production of carbonic oxide at the same time in admixture
therewith as a gaseous fuel. For this purpose the coal or peat is
subjected to the heat of an ascending carbonic oxide flame acting, as
already described, upon the sides of the hollow wall, such sides being
made of open work construction so as to admit the flame to the contents
of the wall. By this means the hydrocarbon gases generated pass off
in admixture with the carbonic oxide and nitrogen of the flame as a
powerful gaseous fuel, the same arrangement being made for the
collection of such gases at the top of the hollow wall chamber as is
now in use at iron blast furnaces for the same purpose. In this modifi-
cation the bottom of the lower part of the hollow wall at which the
flame comes into action, as above described, may also be made the
source of any required proportion of carbonic oxide flame by con-
structing its sides at that part of fire-bars, and forcing through the red-
hot contents of coke or charcoal a hot or cold blast of air, which will
thus partially or wholly consume the coked contents. For this purpose
it is desirable that the fire-barred bottom portion of the hollow wall and
chamber should be divided vertically by means of a transverse partition
from one side of the chamber through the hollow wall to the opposite
side, and by forcing the required blast into one of these bottom sections
from one side through the hollow wall it may be guided by the zig-zag
shelves, as before-mentioned, upwards along the opposite side of the
hollow wall, whilst the blast forced in the opposite direction through the
other bottom section of the hollow wall and chamber may be similarly
guided upwards along the opposite side of that wall. A carbonic oxide
flame alone can be made by this arrangement when a non-gaseous fuel
is employed, and ores or sulphides of metals can be similarly calcined at
the bottom of the hollow wall, either by means of intermixed fuel
charged into the hollow wall therewith, and consumed by means of a
hot or cold blast forced through the bottom of the hollow wall, and
circulating thence upwards, as last described; or by means of a highly
oxidating flame only, such flame being produced by the perfect combus-
tion of a carbonic oxide flame, with a copious admixture of air, and with
or without the presence of steam. The latter flame should be forced by
the blast through the bottom fire-barred sections of the hollow wall,
and made to circulate upwards on both sides of the latter, as herein-
before described.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent,
filed by the said William Alexander Lyttle in the Great Seal Patent
Office on the 15th April 1876.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
ALEXANDER LYTTLE, of The Grove, Hammersmith, in the County of
Middlesex, Civil Engineer, and Fellow of the Chemical Society, send
greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing date the Fifteenth day of October, in the year of
our Lord One thousand eight hundred and seventy-five, in the thirty-
ninth year of Her reign, did, for Herself, Her heirs and successors, give
and grant unto me, the said William Alexander Lyttle, Her special
license that I, the said William Alexander Lyttle, my executors,
administrators, and assigns, or such others as I, the said William
Alexander Lyttle, my exccutors, 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 MEANS AND APPARATUS FOR DEOXIDATING
METALLIC ORES, OXIDES, AND SULPHATES, WHICH IMPROVEMENTS ARE EQUALLY
APPLICABLE TO THE COKING, CHARRING, AND DESTRUCTIVE DISTILLATION OF ANY
SOLID ORGANIC MATTER, TO THE CALCINING OF METALLIC ORES, AND TO
PRODUCTION OF CARBONIC OXIDE FLAME," upon the condition (amongst others)
that I, the said William Alexander Lyttle, my executors or admini-
strators, by an instrument in writing under my, or their, or one of their
hands and seals, should particularly describe and ascertain the nature
of the said Invention, and in what manner the same was to be
performed, and cause the same to be filed in the Great Seal Patent
Office within six calendar months next and immediately after the date
of the said Letters Patent.
THE
NOW KNOW YE, that I, the said William Alexander Lyttle, do hereby
declare the nature of the 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 :—
The distinguishing feature of this Invention is a new method of

page_text: applying the heat of flame by means of a hollow wall, outside which
the flame passes and imparts its heat in various ways to any kind of
solid matter contained within the hollow wall for the purpose either
of deoxidation, coking, charring, destructive distillation, calcination, or
the combustion of solid into gaseous fuel. This hollow wall consists
of two thin adjacent and parallel partitions between which the material
to be so treated is placed by being charged therein continuously from
the top, and subsiding down through the hollow wall as it is withdrawn
upon completion of treatment from the bottom of that wall. This
hollow wall is intended, as herein-after described, to be adapted or
applicable as a perfect substitute for retorts of every form, whether fixed
or rotary, horizontal or vertical, in every existing manufacturing process
in which such retorts are now employed as the means by which solid
matter is subjected to heat. For instance, in the deoxidation of metallic
ores in a crushed or powdered state intermixed with powdered car-
bonaceous matter, the deoxidation of baric or calcic sulphate in the
same way by intermixed carbonaceous matter, the burning of bones
or their destructive distillation into animal charcoal, the revival or
recoking of such or any animal charcoal when exhausted by use as a
filtering agent, the destructive distillation of coal or any bituminous
mineral in making illuminating gas or liquid products of any kind
therefrom, and for the conversion of solid fuel wholly, its ash only
excepted, into gaseous fuel without burning any of its volatilizable
constituents.
In the following description of this hollow wall and its principal
applications, I have given first a general statement of the mode of
construction, combined with an explanation of the principles on which
its economical and efficient working depend, and secondly, I have
added a detailed description with special reference to the accompanying
Drawings.
The hollow wall consists of two thin vertical screens or sides erected
longitudinally parallel to each other, and placed at such a distance from
each other that the material placed between these sides or hollow wall
shall be of the desired thickness for the most efficient penetration of
heat. This hollow wall is contained in a narrow rectangular fire-brick
chamber, the sides of which are parallel to the sides of the hollow wall,
and stand at such a distance therefrom as will only suffice to leave a
free passage for the flame gases by which the hollow wall is heated.

page_text: substance which gives off moisture or other vapours. On one side
of the hollow wall at the bottom a furnace may be provided for the
supply of a carbonic oxide or non-oxidizing flame in any of the usual
well-known methods of producing such flame, and this flame may be
forced through the hollow wall and its contents by a suitable pressure
of the furnace blast. The other or second side of the fire-brick chamber
enclosing the hollow wall must be perfectly air-tight, and may be pro-
vided with a flue or pipe for the removal of the escaping gases and
vapours in order to their being utilized in any desired way. These hot
gases may however be caused, before escaping, to pass from the second
half of the fire-brick chamber directly upward to the corresponding half
of a similar chamber overhead, up through which the hollow wall must
be continuously carried. The flame gases should have no escape from
this half of the upper chamber, except through the charge of material
in that part of the hollow wall, and this material will thus be made
to act as a filter in depriving the escaping gases of their residual heat.
The material thus heated in the hollow wall will subside periodically
to the bottom or hottest chamber as the product is withdrawn from the
bottom of the hollow wall.
The sides of the hollow wall should be made impervious at the line
of the flooring which divides the upper and lower chambers for such
a distance as will prevent the direct passage of the flame gases at that
line vertically upward through the hollow wall. The reason of this
result from using the short band of impervious sides to the hollow wall
is that a passage transversely through the hollow wall into the second
half of the lower chamber, and thence vertically to the corresponding
half of the upper chamber, will be the line of least resistance as
compared with direct permeation upward through the centre or contents
of the hollow wall.
Any number of chambers succeeding each other vertically and thus
arranged may be provided so long as the forcing power of the blast is
not exceeded.
The material under treatment is charged into the top of the hollow
wall after each withdrawal of finished product from the bottom. In
some applications of the hollow wall, especially in that herein-after
described for producing illuminating gas, it is not necessary that the
flame should pass through the material under treatment, because if the

page_text: flame is made to act on both sides of the hollow wall the same heating
effect can be produced by giving a long run to the flame. The latter
object is best attained by providing projecting shelves of iron, fire-clay,
or other refractory material which shall reach out from the side wall of
the chamber to the hollow wall so as to completely close that side space
with a floor except at one end. The next higher floor or shelf should
have its opening for the upward passage of the flame gases at tho
opposite end, and so on, the object being to impart a zig-zag course
with a long journey to the flame on its way of escape upwards. When
this mode of applying heat is used the sides of the hollow wall may
either be made of openwork, as already stated, or of impervious air-
tight plates of metal or other refractory material. The end walls of the
fire-brick chamber into which the two ends of the hollow wall abut may
be furnished with small holes provided with close fitting stoppers
through which the shelves for giving a zig-zag course to the flame may
be periodically cleared of dust, one by one downwards, or out through
the holes in the end walls by a hoe or brush pushed in for that purpose,
or by a blast of air thrown in by a long pipe at the end of a flexible
hose pipe.
In order to use this peculiar apparatus for the deoxidation of metallic
ores, oxides, or sulphates, it is necessary to construct the hollow wall
with openwork sides when carbonic oxide is intended to act either
wholly or partially as the reducing agent, but solid impervious sides
may be used when deoxidation is effected wholly by means of carbon in
a powdered state mixed with the crushed mineral ore, oxide, or salt, and
in that case the more contracted the space is made between the sides of
the hollow wall the quicker will be the reaction because of the more
speedy penetration of the required heat. Openings are provided from
the ends of the hollow wall through the end walls of the fire-brick
chamber against which the hollow wall abuts, and the gases and vapours
generated within the hollow wall can be drawn off by means of branch
pipes leading from these holes into a flue or a main pipe standing
vertically against the end wall outside. This is the general principle of
construction for that modification of the hollow wall which answers for
the destructive distillation of coal, peat, asphalte, oil, shale, or any like
substance, whether such distillation is for the manufacture of illumi-
nating gas or hydrocarbon liquids.
When the material distilled or coked is very liable to glue together

page_text: it is well to interstratify with it alternate layers of lumps consisting of
any refractory material or rows of short cast-iron pipes laid longi-
tudinally so as to provide a horizontal drainage for the gases and vapours
to the openings at the ends of the hollow wall which lead into the afore-
said vertical main pipe.
Chains hung vertically inside the hollow wall or hung in loops with
both ends secured at the top of the hollow wall may be used for
detaching and cleaning away obstructions, because if the vertical chain
is drawn backward and forward between the sides of the hollow wall it
will detach any material which may have become loosely fixed to the
sides; but by pulling up the looped chain and letting it fall again a
much more perfect dislodgment is effected.
When the hollow wall is made of considerable length in a narrow
fire-brick chamber, as aforesaid, it will be necessary to provide it with a
series of air-tight hoppers if gases or vapours of a valuable nature are
generated from the charge under treatment.
The various methods of discharging the contents of the hollow wall at
the bottom as well as of cooling such contents when needful before
discharge will be best understood from the following detailed statement
explanatory of the several Drawings :-
Figure 1 represents a vertical cross section of this hollow wall in one
of its modifications, it is made of two perpendicular and parallel
partitions built of fire-clay slabs A, A, A, resting on horizontal fire-
clay slabs B, B¹, and the latter serve not only to tie the vertical slabs A
securely in position but also act as shelves for the purpose of imparting
a zig-zag course to the flame gases as they ascend along the sides of the
hollow wall. Figure 2 is a sectional side view of Figure 1, the section
being made in the line of A", B", Figure 1. These shelf slabs B, B', are
provided at one or both ends with a projecting rib R, Figure 13, which
rib runs in the direction of the hollow wall sides when the horizontal
slabs are correctly placed. The upper and lower edges of the vertical
slabs A, A, Figure 1, and A, Figure 13, are also provided with a groove
which receives and holds the projecting rib on the horizontal slabs B, B¹.
The other ends of the latter slabs are embedded or built into the brick-
work courses of those solid side walls 9, C, D, and N, B', C¹, D', which
enclose air-tight the hollow wall and its lateral flamo passages formed
by the shelves B, B'. Outside these side walls on both sides are two

page_text: coke chambers running parallel to hollow wall M, C, Y, M, C¹, Y,
Figure 1, with funnel charging tops 5, 5. The hollow wall has a similar
funnel top, as shewn at 5¹, Figure 1, and 8, 8, 8, Figure 2. These
funnel tops can most conveniently be closed with corresponding iron lids
made of a similar tapering or funnel shape so as to fit inside the funnel
top, and thus to act on precisely the same principle as the "cup_and
cone arrangement generally used for closing the tops of blast furnaces
when arrangements are made for conducting off the escaping gases for
further use.
"
The coke chambers M, C, Y, M, C', Y, should be built with an
internal taper increasing vertically downwards, as shewn in Figure 1, so
as to prevent the "scaffolding" or lodgment of the coke.
The outside wall M, 4, 6, of the coke chamber may be braced into
stable connexion with the brick wall N, C¹, D¹, by means of vertical
partitions dividing the coke chamber into several vertical and wholly
distinct sections, each of which should have a separate funnel top and
cone stopper, as already described, the object of the stopper arrangement
in the case of the coke chamber being to prevent the blast and flame
escaping up through the coke.
The four arches standing between Land O, Figure 2, represent the
fronts of four combustion screens in which the bottom of the column or
columns of coke in the coke chambers is consumed by means of a blast
of air, hot or cold, forced through the pipe Q, Figure 1, in the following
manner: The four arches between L and O, Figure 2, are shown at
M, M', and L, J, Figure 1. The lower arch L, M, Figure 2, is shewn
by a section at right angles to that given at M, M¹, Figure 1. The
higher arch L, J, Figure 2, is similarly shewn at L, J, Figure 1. The
various parts on the two sides of the hollow wall A. 5¹, Figure 1, are
exactly alike, one side of this apparatus being a counterpart of the other.
The arched projecting chamber 11, 12, Figure 1, extends along the a
whole of each side of this arrangement, namely from L to O, Figure 2,
and acts as a passage through which the blast from Q at one or both
ends can be distributed to the burning coke by passing through the four
arches.
A clinkering and ash door is provided at 13, Figure 1, opposite the
bottom of each of the arches shewn in Figure 2, and by opening this
door the clinkers at the bottom of the coke column M, C¹, Y, can be

page_text: drawn out through the open space 14, 15, which is left at the bottom of
the cast-iron grating 14, M. The latter grating may be replaced by an
open brick grating, like that shewn at L, J, N, Figure 1, by building the
brick grating on an arch of fire-clay bricks or a cast-iron girder in the line
of 14, so as to leave the needful opening through which to withdraw
clinkers from the bottom of the coke. The coke pressing downward in
the vertical chamber M, C', Y, fills the arched space J, L, Figure 1, and
rests against the grating 14, M³, protruding to some distance through the
open space M on to the floor towards the air chamber 11, 12. The
forced blast entering at Q passes through the grating M, 14, M', of each
arch, and through the thick wall of red hot coke, passing, with all its
oxygen converted into carbonic oxide, thence through the grating L, J, N,
into the space 10, E¹, 9. The flame rises vertically through this space
till it reaches the top of the party walls, 9, 10, Figure 2, which divide
the arches, and it passes thence horizontally along the under surface of
the diverting shelf B¹, Figure 1, and A, B, Figure 2. At B, Figure 2,
the flame rises and travels in the reverse direction underneath the shelf
C, D, and so on, zig-zag, till it escapes at the top through the pipe S, P.
By this means a strong heat is imparted by the direct impact of the
flame against the fire-clay slabs of the hollow wall, over all its face
exposed to the space E¹, 9, B', Figure 1, and a gradually diminishing
temperature thence upward, as the flame surrenders its heat.
In Figure 1 the vertical slabs A forming the sides of the hollow wall
are represented as tied by cast-iron flanged or double-headed bars
E¹, E¹, 16, 16, Figure 1, and in the dotted lines L, 7, 8, 9, 10, also 2, 3,
4, 5, 6, and J, 9, 9, 9, Figure 2.
Any other arrangement of construction, either by increasing the
thickness of the sides A of the hollow wall with cellular, but not neces-
sarily perforated, fire-clay blocks may be adopted in order to secure
solidity to the hollow wall whilst dispensing with the said flanged or
double-headed cast-iron ties when the wall is exposed to a very intense
heat in the space 10, E¹, B¹. The space at 10 between the bottom of
the grating L, N, and the side of the hollow wall A is an ash-pit, which
can be cleared through the stoppered holes Z, Z¹, in the two ends of the
structure. The hollow wall is continued downward below the ash-pit
into the sheet or plate iron cooler 21, 22, Figure 1, which is shewn in
side elevation as filling the arches 1, 2, 3, 22, Figure 2. This cooler is
pre-
cisely similar in principle to the hollow wall, the difference of application
B

page_text: being that the function of the cooler is to deprive the finished contents
of the hollow wall of heat acquired when passing down under treatment.
The sides of the cooler are made of metal, and the diverting shelves 19,
Figures 1 and 2, which may be made of metal, slate, or fire-clay, are
intended to give a zig-zag course to a cold blast of air which is forced or
drawn in below the bottom shelf at the crown of the arch in the side
wall 23, 20, Figures 1 and 2. These shelves, like the shelves B, B¹,
Figure 1, which divert the flame, are secured or built into the side
walls 20, 19, 23, Figure 1, which side walls are sustained upon the
arches 23, Figure 2. The cooler is cut at 18 by any covenient slide
valve, such, for instance, as that used for ventilating the tops of railway
carriage doors. That railway ventilating slide valve is made with a slide
plate slotted transversely and moving longitudinally between two fixed
guide plates, which have exactly similar slots opposite each other.
When the slide plate is moved to the end of its course in one direction
its slots coincide exactly with the slots of the guide plates, and it is then
fully open, but when moved in the reverse direction to the full extent
of its course the slots are all closed. By this means any powdered
matter when subjected to heat in the hollow wall, such as crushed
mixtures of metallic ores or sulphates, with powdered carbon for
deoxidation, or granulated charcoal for recharring, can be conveniently
withdrawn into the hopper 18, 22, which is closed at the bottom 22 with

page_text: and so on till the ash is all blown down into the ash-pit. Any scraper
or other method of cleaning will also answer.
The cleaning holes may be made as rectangular cast-iron boxes built
into the brickwork and closed with cast-iron plugs or lids.
The escaping gases of the flame may be led off by a main pipe from P,
Figure 2, for utilization in any desired way, as at present. Gases evolved
inside the hollow wall will escape in this arrangement through the
joints of the fire-clay slabs A which form the sides of that wall, but a
pipe may be provided at the top between the pipes P, P, Figure 1,
through which the gases from the charge of matter in the hollow wall
may escape.
Any number of such pipes may be carried from the ends of the
hollow wall into a vertical main in order to receive and carry off the
gases and
vapours from bones when being charred in this apparatus.
The walls 11 and 13, Figure 2, are the end walls of the aforesaid
apparatus, and are carried, as shewn in Figure 1, the full width from
the ash doors 13 on both sides up to R, T, where the end walls carry a
platform, and thence as a parapet to W, Z. These end walls are
strengthened by butresses 14 V and 14 V, Figure 2.
The wall 12, Figure 2, in common with the end walls 11 and 13,
carries the entire superstructure resting on the arches 1, 2, and 3,
Figure 2, which arches form also the floor of the coke and air chambers.
Figures 3 and 4 shew another modification of this arrangement, under
which the flame on leaving the coke is forced through the charge which
occupies the hollow wall.
The same letters and numbers in Figures 1 and 4 refer to the same
parts, and the two arrangements are identical in all respects, excepting
only at the bottom of the hollow wall where the heat first acts.
The fire-clay slabs A which form the sides of the hollow wall rest
upon solid brick arches N, K, which are built continuously through
from J, L, and are fitted with openwork firc-block grating, as shewn in
the four arches L, M, H, W, O, Figure 2. These brickwork arches,
Figures 3 and 4, on which the slabs A rest are transversely cut with an
opening between K and N equal at least to the width of the bottom of
the hollow wall, and a similar opening down to H is left through the
B 2

page_text: fire-block grating L, N, K, S. By this means the flame from the coke
can be forced through the grating or openwork L, N, then through the
charge of material under treatment in the hollow wall, and thence
through the openwork or grating K, S, which forms the back of the
hollow wall at this point. The flame gases then enter the space 16 E¹, X,
and passing upward thence to the shelf B traverse that side of the hollow
wall zig-zag along the diverting shelves, as already described.
Figure 3 shows a sectional side view of this arrangement provided
with four fire-arches only, two of which M, M', are on one side, the
front in the Drawing, and have their flame forced through the hollow
wall, as last described. This flame from two arches then rises and
traverses the whole length of the shelves on the back side of the hollow
wall. The two fire-arches S, T, shewn in dotted lines in Figure 3, are
at the back of the hollow wall, and the flame on being forced through
the hollow wall enters on the front side a space, like that shewn
at 16 E¹, X, in Figure 4, and ascends vertically till it meets the
shelf A, B, along which it passes. The flame runs thence along the
whole length of the hollow wall to C, and so on zig-zag up to the top.
The fire-clay grating forming the back of the hollow wall at K, S,
Figure 4, must be built either with numerous small openings or in the
manner described with reference to Figures 14 and 15, so as to give the
requisite vent for the passage of the flame without allowing the
free escape of the contents of the hollow wall. The bottom of the
space 16 E, X, Figure 4, must have an opening like Z, Figure 2, at
oue end, through which to remove ash and cinders. This arrangement
is peculiarly well suited to the production of fuel gas from bituminous
or any fuel by charging the fuel in at the top and allowing the hydro-
carbon gases and vapours
distilled from the fuel to pass off in admixture
with the carbonic oxide of the flame escaping by the diverting shelves.
By causing these mixed gases and vapours to pass through an “bydraulic
main" and " scrubber," as in ordinary gasworks, many valuable
ammoniacal and tarry liquids will be obtained. When fuel gas is to be
thus made it is not necessary to provide the coke chambers M, 14, C¹,
Figure 4, at the sides of the hollow wall, because if the hollow wall is
made to widen out to a thickness of about 18 or 24 inches between K, N,
and H, the coke, which alone will remain at this point as the charge
of fuel descends, can be consumed into carbonic oxide by causing the
blast of air to pass direct through L, N, the wall of ignited coke, and

page_text: thence the flame thus produced will pass upward to the shelves, where
the heat of the flame in its zig-zag course will reduce the fuel to coke
and hydrocarbon gases and vapours.
In this application of the hollow wall principle the bottom of the
hollow wall may be at H, Figure 4, with an opening in one or both
sides from L through 10 to H for the purpose of extracting clinker
periodically. A bottom discharging arrangement with water seal, as
described in reference to Figure 8, will however be found best, because
by removing a portion of the bottom coke under water as there provided
a general subsidence from time to time can be effected in the contents
of the hollow wall, and the mixture of ash, coke, cinders, and clinkers
thus brought down can be removed, and the unconsumed fuel can be
separated for use; "spent tan" can thus be converted into fuel gas at a
profit.
Figures 5 and 6 relate to another modification of the hollow wall
which is best suited for the production of illuminating or hydrocarbon
gas, or for any other purpose now conducted in retorts by external heat
with complete exclusion of any communication between the contents of
the retort and the heating flame or the air. This is a condition essential
to the distillation of asphaltes and oil shales, to the production of pyro-
ligneous acid from woody matter by destructive distillation, and to a
large number of other uses in chemical technology. In this modifica-
tion also the entire general arrangements of the structure may be as
shewn in Figures 1 and 2, the only difference being in the hollow wall,
which consists of a series of cast iron or fire-clay flattened retort segments
fitting into each other vertically, with spigot and socket joints made air-
tight in a peculiar manner, as herein-after described.
T, S, Figures 5 and 6, represents one of these flattened retorts, T, S,
in Figure 6, shewing the end of the retort, and T, S, Figure 5, its side.
F, D, S, is the socket at the top of T, S, in which the bottom or spigot
of the next higher retort D, C, stands. The bottom retort receives the
direct impact of the flame from the coke through the openwork at
L, J, E, and this length had better be lined externally with solid or
perforated fire-brick up to a point above the highest entrance of the
flame. P, R, represents a branch pipe to carry off gases and vapours
from each of these retort segments, which build up this form of hollow
wall, and each of these branch pipes may be flange bolted on to a

page_text: vertical pipe connecting it with an hydraulic main and other ordinary
gas works appliances. The spigot and socket connexions of these retort
segments may be made air-tight by the well-known "rust joint" cement
applied as herein-after described. The shelves B, B¹, for diverting
the flame are provided as already described, but they rest wholly in the
side wall of the chamber, and abut only against the outside of the cast-
iron or fire-clay segments.
Figures 7 and 8 shew a convenient form of cooler and water sealed
discharger applicable to all cases of destructive distillation already
referred to, and to the cooling of any substance not liable to oxidation
or injury by immersion into water when hot. 2, 3, and 6, 7, Figure 8,
are two brick walls, which are carried downwards below the floor of the
hollow wall structure, similarly to 20, 23, the side walls of the cooler in
Figure 1. The walls 2, 3, and 6, 7, Figures 7 and 8, are not however to
form part of a cooler, but merely to act as discharging guides for the
contents of the hollow wall. These walls rest upon the iron girders 4
and 5, Figure 8, and the girders are almost covered by the water which
fills the tank P, Z, W, underneath. This tank may be of any desired
depth, about four feet being convenient, as the net depth below the
girders and its bottom should be carried as an inclined plane rising out
of the water to each end in the directions of the chains C, C¹.
F, V, W, G, Figure 8, is a wheeled combination of a hoc and shovel,
an end view of which is shewn in Figure 7. Its floor between F and G
lies close to the floor of the tank, and is strongly made of plate iron with
a chain from each end F, C, and G, C¹, by which the apparatus can be
hauled to the top of the inclined plane at either end of the tank. This
bottom or shovel is divided in the middle between the wheels by the
vertical plate-iron division or hoc V, W, Figures 7 and 8. When this
apparatus, which I shall call the dredger, stands at one side of the
girders 4, 5, Figure 8, near P, the discharged contents of the hollow
wall stand piled underneath in the tank with the chain G, C¹, resting
underneath. When the time arrives for the next discharge the
chain G, C¹, is hauled by suitable power, and the dredger advancing
along the bottom of the tank removes the whole of the coke or other
material, which is immediately replaced by a further fall of the contents
of the hollow wall on the other side of the hoe V directly the latter is
hauled across the bottom of the discharging walls 4, 5, as the dredger
passes off to Z. At the latter end the dredger with its load is hauled

page_text: Figures 10 and 11 shew in broken sectional plan an arrangement by
means of which to build up air-tight retort segments for constructing a
hollow wall on the principle already partly explained in reference to
Figures 5 and 6. Figure 10 represents the sectional plan of one end
and part of two sides of such a built up retort, and Figure 11 represents
the plan of the other end of the same retort, shewing the plan of the
socket L, E, M, in which the spigot end of the next higher retort sits.
J, K, and. J¹, K¹, are the two sides of the required segment of the retort
cast without cores, or moulded as flat plates, and they are bolted at both
ends either to two U shaped end pieces N, K, K¹, T, or to one of such
pieces at one end, and an H junction piece at the other end, which
serves to unite several side plates into one length of hollow wall retort.
These end pieces and H junction pieces are also made of cast iron or
fire-clay, and of exactly the same depth as the side plates J, K, J¹, K',
so that when the four parts are bolted together they form a retort
segment precisely similar to T, S, in Figures 5 and 6, one of the side
plates J, K, Figures 10 and 11 being provided with the gas pipe P, R,
shewn in section between these two Figures. This pipe of the same
form as shewn in Figure 6, with drooping funnel mouth inside to prevent
stoppage therein of the descending charge, may be cast or made as one
piece with the side plate J¹, K', or may be bolted to it.
Owing however to the greater destructibility of malleable iron when
exposed to heat it will be better in many cases to use cast-iron bolts
slotted near the ends for the purpose of being secured by the action of
wedge-shaped keys also of cast iron. When this cast-iron bolt is
inserted the head should be inside with the slot vertical outside, and
considerable tightness of the plates can then be ensured by driving
down the key, one edge of which must press against the side plate,
through which the bolt passes and the other edge against the outer end
of the slot.
The H piece A, S, D, and the end piece N, M, T, Figures 10 and 11,
should be cast or made with a semi-cylindrical groove, running from top
to bottom of the flanges in the line of the bolt holes, as shewn in
section by the dotted lines at 2, 3, 4, 5, 6, and 7. These grooves should
be double as wide as the bolts, and the bolt holes should pass through

page_text: the groove at equal distances from its two sides. When all the four
plates are put together and bolted in the position which this segment of
the hollow wall is to occupy, a mixture is made of sulphur and iron
filings or powdered reduced iron, in any of the various relative pro-
portions used for making the well-known "rust joint," with sal
ammoniac, and poured into the top of each groove. This mixture of
sulphur and powdered iron being dry runs readily down to the bottom
of the groove, and fills it perfectly round all the bolts. A solution of
chloride of ammonium (sal ammoniac) of any desired strength is then
poured into the top of the groove and fills it, when the usual reaction
between the iron and sulphur immediately takes place, uniting the
jointed plates and bolts into one solid gas-proof mass, which is not
injured by any heat which can be employed.
In order to prevent the waste of the powdered mixture of iron and
sulphur, as well as of the ammoniacal solution, it is desirable to
thoroughly lute the bottom of each socket with plastic clay, mixed with
iron dust and sulphur in the "rust joint" proportions, before the spigot
end of the next segment is set in position. When the next segment is
set up and cemented at its joints, as above described, a supply of
powdered iron and sulphur is poured into the socket outside the spigot
of the last mentioned segment, upon the top of the foundation of wet
clay, as aforesaid, and this powder on being wetted with the said solution
of chloride of ammonium becomes a solid mass, firmly uniting tho
socket and spigot of the two segments.
Fine sand or any other hard insoluble powder may be mixed with the
powdered iron and sulphur in making the above modification of the
"rust joint," and the most usual proportions are one ounce of sulphur
to five pounds of iron, with two ounces of chloride of ammonium.
The modification of the hollow wall herein-before described in
reference to Figures 3 and 4 is peculiarly applicable to the deoxidation
of metallic ores when a mixture of the crushed ore with powdered fuel
or carbonaceous matter is made into lumps or bricks by means of clay
as the cohering medium. These lumps when charged into the top of
this hollow wall will be dried, hardened, heated, and partially deoxidated
whilst subsiding down between the solid sides as the finished charge is
periodically withdrawn from the bottom. On reaching the fire-clay
openwork sides of the hollow wall at K, N, Figure 4, the flame is forced

page_text: through the already red-hot lumps and fragments, and the deoxidation
of the ore is completed. This method of reducing ores is especially well
suited for the smelting of zinc, because the gradual and complete
expulsion of every trace of moisture from the agglomerated lumps of
crushed zinc ore, carbonaceous matter, and clay, will largely augment
the yield of metal, and economise the fuel now employed. When the
compounded lumps of zinc ore and carbon become red hot reduction
begins, and metallic zinc will volatilize through the joints of the fire-
clay slabs composing the hollow wall, or out through branch pipes
leading through the ends or sides of the brick chamber in which the
hollow wall stands, as already described, such branch pipes being
intended and constructed to act as receivers of the volatilized zinc, with
air-tight openings, through which the zinc can be withdrawn. All such
branch pipes may also be carried into one vertical main pipe, which
shall not only serve as a receiver of zinc, but also to carry off the com-
bustible gases which are escaping from the shelves at the top of the
hollow wall. When the volatilized zinc forms a dust on the shelves B, B,
Figure 4, it can be removed through the holes V, VI, Figure 2, or
pushed down to the brickwork over K, Figure 4, where it melts and
falls into the ash-pit or hearth at the bottom of the space X, E³, 16,
from which it can be tapped off as pig iron is from the hearth of a blast
furnace. Any zinc remaining in the ore is completely expelled when
the compounded ore reaches the point, where it meets the direct impact
of the flame at K, N, S, L, Figure 4.
Iron ore and carbonate of zinc, or a well calcined sulphide of zinc,
can be mixed together for reduction in the way last described, provided
that enough carbon is intermixed to answer for the deoxidation of all
the metal present, and in that case the zinc is all expelled, as stated
above, whilst the reduced iron is withdrawn from the bottom of the
hollow wall cooler.
When crushed, granulated, or splintered ore and similarly broken
fuel are intermixed and charged without being thrown into coherent
lumps as above described, the result is as effective, especially when the
apparatus shewn at Figures 3 and 4 is used, and the thickness of the
vertical wall of crushed or splintered ore and carbon between K, N,
and H, Figure 4, is not too thick to prevent the passage of the
flame.

page_text: The deoxidation and fluxing, otherwise known as "smelting" of any
metal can also be advantageously effected by this latter modification of
the hollow wall, and by its means the reduced or unsmelted metal
obtained by the deoxidation of the ore in the foregoing or any other way
can be readily fused into ingots. For the latter purpose the reduced
powder of the metal which has to be melted is mixed with clay, lime,
and silica or other convenient powdered fluxes, gauged in such pro-
portions that the melting point shall not be below that of the reduced
metal, and the lumps are charged into the top of the hollow wall,
Figures 3 and 4. On reaching K, N, the metal and the fluxes are fused
together, and fall into an ordinary blast furnace hearth of the well
known common type which forms the bottom of the hollow wall at H
when the contents are thus got rid of by fusion.
When the complete smelting of any metal is to be effected all the
arrangements and results are precisely the same as last described, with
this exception only, that the compounded lumps or unlumped mixture of
crushed ore must also contain the requisite proportion of reducing
carbon in addition to the necessary fluxes.
When melting or smelting is to be done the plan of constructing the
fire-clay openwork described below in reference to Figure 14, will
answer best, as the means of forming the sides of the hollow wall
between K, N, and S, H, Figure 4. It will also answer well in all
modifications of the hollow wall principle in which flame is forced
through the charge of the hollow wall, or where a blast of air is forced
through the charge for its calcination or combustion into fuel gas. This
mode of building shewn at Figure 14, can also be employed as explained
in reference to Figure 15, for building the whole superstructure of the
hollow wall in any of the aforesaid applications of the principle in which
air-tight closeness of the sides of the hollow wall is not needed. When
the bottom of the hollow wall is thus constructed the aforesaid lumping
of ore or reduced metal with clay is unnecessary, and the foregoing
mixtures for deoxidation, melting, or smelting may be employed as
powdered mixtures without consolidation.
Figure 14 represents a cross section of a piece of openwork bricklaying
of this kind, the bricks being made with cranked ends like the heel of a
boot, so that when laid over riding each other, as shewn in Figure 14,
they shall not be liable to displacement when laid at an angle of about

page_text: 45 degrees. They may be laid with open joints, as shewn at Figure 15,
that Figure being a side elevation of Figure 14. By arranging such a
brickwork to form the containing sides of the hollow wall, and placing
the bricks with the longer side of the crank pointing into the hollow
wall at an angle of 45 degrees, it is clear that the effect will be precisely
similar to that of the Venetian blind arrangement already described in
reference to Figures 9 and 12. Gas will have free course into or out of
the hollow wall, but none of the solid contents can escape owing to the
overlap of the inclined bricks. Figure 16 shews this method of building
as applied to the upper part of the hollow wall S, T, being one side of
the hollow wall and the shelves (P) so shaped as to become interlocked
with the inclined cranked bricks of the hollow wall, as well as firmly
held by the brick wall M, N, of the chamber, in which as already stated
the hollow wall stands.
When a cooler, as herein-before described in reference to Figures 1
and 2 is employed, or when the contents of the hollow wall have been
deprived of heat in the under-mentioned way, it will be possible with
any of the following simple arrangements to dispense wholly with the
use of the discharging hopper, and more costly slide valves described in
reference to Figures 1 and 2.
Figure 17 represents a discharger which acts somewhat like the well
known bird fountain attached to birdcages, because when the trough W, T,
has become filled with the contents of the hollow wall no more of such
contents can descend until the trough is discharged; H, W, shews part
of the cooler of the hollow wall in cross section, and W, T, shews a
cross section of the discharging trough. One or both ends of this
trough are fitted with a shoot, and by running a hoe or road scraper
along the trough, the whole of its contents will be driven down the
shoot at the end into a truck placed for the purpose. At the same time
a further downward fall of the contents of the cooler will take place
behind as the scraper advances, provided the scraper is made wide
enough, as it should be, to clear out the full width of the trough at one
run. The width of the trough W, T, need not exceed double the depth
of the longitudinal opening left at W along one side of the bottom of
the cooler H, W.
19 shows the hottom of the cooler A B. fitted with a lonci

page_text: opening is closed throughout its length by the rotary bar B which
carries four radial feathers or ribs, and by rotating this bar in the
direction of the arrow the contents of the cooler will be discharged down
the shoot S so long as the bar B is is turned. The same result is also
obtained by means of the swing bottom shewn in Figure 19;
A, B, represents a cross section of the cooler with the swing trough pivoted
at each end hanging under it. It is evident that with the trough in this
position nothing can fall from the cooler, but when the swing trough is
forced to one side, as shewn at B¹, the contents can be freely discharged
to any desired extent.
When infusible compound lumps of powdered ore and carbon are
subjected to reduction as already described, it may be desirable when
rapid cooling is required to crush such lumps at the bottom of the
hollow wall, and thus admit the use of a cooler with sides placed close
together, so as to ensure more rapid absorption of the heat by the
ascending current of cold air outside, as already described in reference
to the cooler of Figures 1 and 2. For this purpose the bottom of the
hollow wall may be filled with an arrangement of rotary fire-bars laid
either longitudinally or across the hollow wall, and provided with pro-
jecting feathers or ribs. The axles of these fire-bars may be geared
together by a train of spur wheels at one end, so that the ribs of the
bars shall never touch, and as many as possible of the spur wheels
should be driven by one shaft, the axle of which alone should be exposed
to the air by passing through a stuffing box, all the other parts of this
fire-bar arrangement being wholly shut in from any admission of air.
When these fire-bars thus loosely set asunder are rotated, they pinch
and let down the broken compound into the funnel-shaped top of the
narrow cooler.
Another crushing arrangement is shewn in Figure 18. A represents
the cross section of one double-feathered heavy crushing bar, which on
being rocked from side to side by a lever attached to its projecting and
glanded axle, pinches and crushes the lumps against the cast iron or
other hard side blocks which form the termination of the hollow wall.
Any convenient crushing arrangement can however be adopted for this
purpose.
Figure 20 shews a method of cooling the contents of the hollow wall
without the use of any deep air cooled sheet iron cooler, as described in
reference to Figures 1 and 2, and without any preparatory crushing of

page_text: the lumps of compounded and reduced ore, or any other matter which
may come down from the hollow wall; C, P, P, represents the discharger
which depends from the bottom of the hollow wall and dips into the
longitudinal chamber P, P, R, R, a cross section of which is given.
This latter chamber is provided with iron pipes running from end to end,
and placed so far apart as to present no obstacle to the free descent of
the charge from the hollow wall. These pipes are moreover either
slotted or perforated on their lower sides, and through them cold non-
oxidizing gases can be forced, so as to pass through and absorb the heat
of any red hot matter which may be in the chamber.
Such cooling gas
may be prepared by passing the carbonic oxide and nitrogen taken from
the top of the hollow wall shelves, or from any other source of carbonic
oxide, as free as possible from carbonic anhydride by burning coke with
atmospheric air, and forcing it into the pipes of the chamber P, P, R, R,
after traversing a set of pipes cooled by water or exposure to the air.
By using a suitable air pump the same gas may be driven through the
contents of the cooling chamber, and thence by suitable escape pipes
at P driven through the pipes by which its heat derived from the
contents of the cooling chamber is again abstracted. It can thus be
worked in a circle with but little waste.
When the oxidating effect of steam is not likely to come into
injurious operation, as in the case of making or reburning animal
charcoal, steam may be turned into the tubes in the chamber P, P,
R, R, and by this means the charcoal is speedily reduced to the tem-
perature of steam, and can no longer ignite when exposed to the air for
complete cooling in any desired way.
In applying the hollow wall to the deoxidation of metallic ores or
sulphates for the purpose of obtaining metals or sulphides by the action
of heat on a mixture, the powdered substance to be deoxidated with
powdered carbonaceous matter, the carbon of the latter should be in
such proportion as shall be the proper chemical equivalent for the total
removal of all the oxygen present in the intermixed metallic oxide or
sulphate. This rule will fully guide any skilled chemist in using the
hollow wall for any of the said purposes of deoxidation.
When iron ore is intermixed with carbonaceous matter considerably
in excess of that proportion required for deoxidation of the ore,
"cementation" can be effected by slightly prolonged heating in the

page_text: hollow wall, and the reduced iron will thus absorb enough of the
redundant carbon to pass into the condition of powdered "blister" steel.
If however the heating given for such cementation should be too high,
there is a danger of the reduced iron absorbing to much carbon to be fit
for use as steel, except when melted with enough pure reduced iron to
bring down the total per centage of combined carbon in this mixture to
the required steely amount. This method of compounding highly
carburetted with wholly pure uncarburetted reduced iron, will furnish
the ready means of providing all kinds of hard or mild steel with
uniform certainty.
The safest and most rapid method of conducting cementation by
means of the hollow wall is to devote one or more hollow walls wholly
to the reduction of iron ore to the pure metallic state, and then to crush
the resultant product obtained from the cooler of this hollow wall.
This powdered product should then be passed through a winnowing
machine precisely as grain is winnowed by farmers, and by this means
the gangue of the ore and any redundant carbon are driven away to
distances proportional to their relative specific gravities, whilst the
reduced iron falls short in a heap or into a shoot for its removal pro-
vided in the floor. This reduced iron should next be mixed with any
purc kind of powdered carbon, more particularly powdered peat charcoal,
and it should then be charged as a loose mixed powder into another
hollow wall apparatus, which may be devoted wholly to cementation
only, the mode of constructing the latter being that shewn in reference
to Figures 1 and 2. By means of tubular trying holes provided in the
ends or sides of this latter hollow wall, the extent and sufficiency of the
cementation can at any moment be ascertained by drawing out samples
in a tubular scoope or trying rod, and the heat or the speed of discharge
can be safely regulated accordingly.
The redundant carbon having again been winnowed, as above
described out of this resulting blister steel powder the blister steel may
be made into lumps with clay and fluxes, and melted as already
described in reference to Figures 3 and 4; or they may be melted in
any convenient cupola provided with flame generated inside combustion
chambers, so as to prevent the contact, and therefore contamination of
the molten blister steel by the burning fuel. The cast steel thus
produced may be tapped off in ingots from beneath the overflowing slag
of the hearth of the melting furnace.

page_text: All the aforesaid modifications of the bollow wall principle, in which
the mode of construction is adapted to the use of a sufficiently high
temperature are available as the means of applying heat to mixtures of
crushed metallic ores, oxides, or sulphates with powdered carbon for
reduction, whether these materials are charged into the hollow wall as a
loose mixture or as solid lumps agglomerated by clay as herein-before
described. When the heating flame has access to the contents of the
hollow wall undergoing deoxidation, such flame must be of a decidedly
reducing character by containing a large proportion of carbonic oxide
with the smallest possible admixture of carbonic anhydride; but when
the hollow wall is made with impervious or gas-tight sides no such pre-
caution need be observed, and the flame gases may be perfectly
consumed by a suitable supply of hot or cold blast whilst circulating
along the sides of the hollow wall.
When the hollow wall is constructed of openwork materials as
described in reference to Figures 3, 4, 14, 15, and 16, it is specially well
adapted to the calcination of metallic ores, or of lime, or of those
mixtures of lime and clay or mud known as hydraulic cements, the
only essential condition being that the flame generated in the coke
chamber at the side shall, when impinging against or passing through
the contents of the hollow wall be accompanied by an abundant supply
of free atmospheric oxygen, and with or without a supply of steam as
an additional oxidizing agent. In using the hollow wall for this purpose
the shelves on one side may be traversed by a highly heating flame, and
the shelves on the other side by a blast or current of hot or cold air,
the thickness of the charge within the hollow wall being curtailed by
providing the smallest convenient distance between its sides, in order
that the calcination of its contents may be effected with the greatest
energy and speed.
This application of the hollow wall as an economical agent for
effecting calcination makes its use valuable in the manufacture of
sulphuric acid, because the pyrites containing the required sulphur may
be calcined in the hollow wall continuously on a very large scale, and
the gases evolved may be carried into leaden or other chambers for
conversion into sulphuric acid as at present.
The term "blast" used in this Specification as designating the air
supplied for burning fuel, or otherwise, must be understood to mean a

page_text: current of air produced either by a blowing or exhausting apparatus,
and for the latter purpose the draught of a tall chimney will sometimes
suffice.
Having now fully described the nature of my Invention, and the
principal methods by which it can be carried into effect, many other
modifications being obviously possible without any departure from the
aforesaid principles of construction and use, what I claim is,—
Firstly. The construction and use of the means and apparatus, which
I have designated the hollow wall arrangement, as a new means of
applying heat to any solid matter, substantially as herein-before
described, and especially for the deoxidation of metallic ores, oxides,
and sulphates, for the charring, coking, and destructive distillation of
any solid organic matter, such as bone, coal, wood, and peat, for the
calcining of metallic ores with or without the production thereby of
sulphuric acid, and for the production of fuel gas containing the fixed
carbon of the fuel in the form of carbonic oxide.
Secondly. The various arrangements for discharging to hollow wall, as
described.
Thirdly. The various arrangements for cooling the contents of the
hollow wall before or at the time of discharge, more especially the
injection of steam or of a cold non-oxidizing blast of gases, substantially
as described.