IMPROVEMENTS IN THE MANUFACTURE OF ZINC, AND IN THE CONSTRUCTION FURNACES CONNECTED THEREWITH, WHICH LATTER IMPROVEMENTS ARE ALSO APPLICABLE TO OTHER METALLURGICAL PROCESSES
Year: 1866

page_text: LETTERS PATENT to Charles William Siemens, of Great George Street,
Westminster, in the County of Middlesex, Engineer, for the Invention
of "IMPROVEMENTS IN THE MANUFACTURE OF ZINC, AND IN THE CONSTRUCTION
FURNACES CONNECTED THEREWITH, WHICH LATTER IMPROVEMENTS ARE ALSO
APPLICABLE TO OTHER METALLURGICAL PROCESSES."
OF
Sealed the 28th August 1866, and dated the 5th March 1866.
PROVISIONAL SPECIFICATION left by the said Charles William Siemens
at the Office of the Commissioners of Patents, with his Petition, on the
5th March 1866.
I, CHARLES WILLIAM SIEMENS, of Great George Street, Westminster, in
the County of Middlesex, Engineer, do hereby declare the nature of the
said Invention for "IMPROVEMENTS IN THE MANUFACTURE OF ZINC, AND IN THE
CONSTRUCTION OF FURNACES CONNECTED THEREWITH, WHICH LATTER IMPROVEMENTS
ARE ALSO APPLICABLE TO OTHER METALLURGICAL PROCESSES," to be as follows:-
In the production of zinc by the methods now generally adopted not only
is very considerable delay and difficulty experienced in the manipulation of
the materials from which the metal is to be extracted, but serious loss of
time and expenditure of fuel are occasioned owing to the process being inter-

page_text: mittent and necessitating the charging and discharging of the zinc pots, retorts,
or tubes at the commencement and at the termination of each operation.
Now this Invention consists in so arranging the zinc pots, retorts, or tubes
as that they can be continuously or otherwise charged with the materials for the
production of zinc, and after the volatile metal has been distilled therefrom
that the residue can be removed, continuously or otherwise, without in any
way arresting the ordinary working of the furnaces, thus effecting a very
considerable economy of time and fuel.
In carrying out this Invention the zinc pots, retorts, or tubes are placed
vertically or nearly so within a furnace in such a manner as that they can be
uniformly heated, and for this purpose it is preferred to employ what is known as
a Siemens' regenerative gas furnace, which is protected by Letters Patent dated
the 22nd of January 1861, No. 167, and to arrange the distillatory apparatus
either vertically or otherwise, and connect the other portion of it with a
reservoir in which the materials about to be operated upon are stored, and to
the lower end of which apparatus there is connected a discharge pipe, through
which the residue of the operation may be discharged. That portion of the
distillatory apparatus in which the production or volatilization of the zinc is
effected is furnished with exit pipes or tubes, through which the metal may be
conducted and collected; these tubes may be placed either. on the exterior of
the distillatory apparatus or may be made to pass into or through the same,
their position being entirely dependent on the mode of distillation adapted,
whether per ascensum or per descensum. The passage of the materials
through the distillatory apparatus may be regulated by means of slides or
other arrangements in connection with the discharge tubes or pipes.
My Invention also consists in particular arrangements of the gas furnace
before alluded to, whereby a considerable number of tubes or vertical retorts
may be arranged in double rows or nests within a sunk chamber, into which
the gases previously heated by means of regenerators are admitted therefrom
alternately at the one side and the other in such a way that the air is allowed
to enter above the heated combustible gases, which latter, by virtue of their
lesser specific gravity, rise and mix with the air, effecting combustion, which
combustion is facilitated owing to the more thorough admixture resulting from
their passage through and between the tubes or retorts contained in the
heated chambers. The same improvement in the arrangement in gas
furnaces is applicable to other purposes, that is to say, when it is desired to
heat uniformly a number of tubes or crucibles or ingots of metal, these are
placed vertically or obliquely into sunken or oblong chambers constructed in
a manner similar to that previously described. When it is desired to apply
A

page_text: this Invention to the fusion of steel or of other metals a double row of pots
or crucibles containing the metal is introduced from above into such oblong
chamber, and opposite each pot or crucible a lateral opening is provided for
the alternate inlet or outlet of the previously heated gases and air, the direc-
tion of which is from time to time reversed, care being taken that the air be
always admitted above the heated gases. The flame traversing the chamber
from side to side heats all the pots or crucibles uniformly, each pot or
crucible being under precisely the same condition irrespective of the length
of the chamber. The products of combustion pass through the corresponding
apertures in the opposite side of the chamber, and are thence conducted
through the regenerators, and finally pass into the chimney.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Charles William Siemens in the Great Seal Patent Office on
the 5th September 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, CHARLES
WILLIAM SIEMENS, of Great George Street, Westminster, in the County of
Middlesex, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Fifth day of March, in the year of our Lord
One thousand eight hundred and sixty-six, in the twenty-ninth year of Her
reign, did, for Herself, Her heirs and successors, give and grant unto me,
the said Charles William Siemens, Her special license that I, the said Charles
William Siemens, my executors, administrators, and assigns, or such others as
I, the said Charles William Siemens, my executors, administrators, or 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 "IMPROVE-
MENTS IN THE MANUFACTURE OF ZINC, AND IN THE CONSTRUCTION OF FURNACES
LATTER IMPROVEMENTS
CONNECTED
WHICH
THEREWITH,
ARE ALSO APPLICABLE
то
OTHER METALLURGICAL PROCESSES," upon the condition (amongst others) that I,
the said Charles William Siemens, my executors or administrators, by an
instrument in writing under my hand and seal, 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

page_text: Office within six calendar months next and immediately after the date of
the said Letters Patent.
NOW KNOW YE, that I, the said Charles William Siemens, do hereby
declare the nature of my said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the accompanying Drawings, and
to the letters and figures marked thereon, that is to say :--
In the production of zinc by the methods now generally adopted great loss
of time and expenditure of fuel are occasioned owing to the process of
distillation being intermittent and necessitating the charging and discharging
of the zinc pots, retorts, or tubes at the commencement and at the termination
of each operation.
Now my said Invention consists in so arranging the zinc pots, retorts, or
tubes as that they can be continuously or otherwise charged with the materials
for the production of zinc, and after the volatile metal has been distilled
therefrom that the residue can be removed, continuously or otherwise, without
in any way arresting the ordinary working of the furnaces, thus effecting a
very considerable economy of time and fuel.
In carrying out my Invention the zinc pots, retorts, or tubes are placed
vertically or obliquely within a furnace in such a manner as that they can be
uniformly heated, and for this purpose I prefer to employ what is known as
Siemens' regenerative gas furnace, which is protected by Letters Patent
bearing date the Twenty-second of January One thousand eight hundred and
sixty-one, No. 167, and to arrange the distillatory apparatus either vertically
or otherwise, and connect the upper portion of it with a reservoir or chamber
in which the materials about to be operated upon are stored, and to the lower
end of which apparatus there is connected a discharge pipe through which
the residue of the operation may be discharged. That portion of the
distillatory apparatus in which the production or volatilization of the zinc is
effected is furnished with exit pipes or tubes through which the metal may be
conducted and collected these tubes may be placed either on the exterior of
the distillatory apparatus or may be made to pass into or through the same,
their positions being entirely dependent on the mode of distillation adopted,
whether per ascensum or per descensum. The passage of the materials
through the distillatory apparatus may be regulated by means of slides or
other arrangements in connection with the discharge tubes or pipes.
My Invention also consists of certain particular arrangements of the gas
furnace before alluded to, whereby a considerable number of tubes or vertical
retorts may be arranged in double rows or nests within a sunk chamber, into

page_text: which the gases previously heated by means of regenerators are admitted
therefrom alternately at the one side and the other in such a way that the air
is allowed to enter above the heated combustible gases, which latter by virtue
of their lesser specific gravity rise and mix with the air, effecting combustion,
which combustion is facilitated owing to the more thorough admixture
resulting from their passage through and between the tubes or retorts
contained in the heated chamber. The same improvements in the arrange-
ment of gas furnaces is applicable to other purposes, that is to say, where it
is desired to heat uniformly a number of tubes or crucibles or ingots of metal,
these are placed vertically or obliquely into sunken or oblong chambers
constructed in a manner similar to that previously described.
When it is desired to apply this Invention to the fusion of steel or of other
metals a double row of pots or crucibles containing the metal is introduced
from above into such oblong chamber, and opposite such pot or crucible a
lateral opening is provided for the alternate inlet or outlet of the previously
heated gases and air, the direction of which is from time to time reversed,
care being taken that the air be always admitted above the heated gases.
The flame traversing the chamber from side to side heats all the pots or
crucibles uniformly, each pot or crucible being under precisely the same
condition irrespective of the length of the chamber. The products of com-
bustion pass through the corresponding apertures in the opposite side of the
chamber, and are thence conducted through the regenerators, and finally pass
into the chimney.
And in order that my said Invention may be fully understood I shall
now proceed more particularly to describe the same, and for that purpose
shall refer to the several Figures on the annexed Sheets of Drawings, the same
letters of reference indicating corresponding parts in all the Figures.
Figure 1 on Sheet 1 of my Drawings represents a transverse vertical section
taken along the line 1, 2, in Figure 2 of my improved arrangement of furnace
for effecting the production of zinc by a continuous process by the aid of a
regenerative gas furnace; Figure 2 is a longitudinal vertical section of the
same taken along the line 3, 4, in Figure 3; Figure 3 is a sectional plan
taken along the line 5, 6, in Figure 2; and Figures 4 and 5 are sectional
details which I shall herein-after more fully refer to.
a, a, are a series of vertical retorts or tubes disposed in groups and open at
the top and bottom, as shewn; these retorts or tubes are situate in the
heating chamber 6 of the regenerative gas furnace, the flame playing freely
round such retorts or tubes. The open mouths of these retorts pass through
slabs c of plumbago or fire-clay which form the floor of a chamber d, into

page_text: which the zinc ore is fed from a doube closing hopper d', and whence the ore
descends into the several retorts a, a; f, f, are the air regenerators, and
9, 9', the gas regenerators, which communicate respectively by the air and gas
apertures h, h', and i, i, with the recesses e, e¹, opening into opposite sides of the
heating chamber or furnace b. The solid residium passes from the retorts into
the inclined passages k, and descends by the vertical passage 1, provided with
sliding doors at 7, into the vault or chamber m, where it is collected and
removed from time to time. The fume or vapour is conveyed from the
retorts by the central exit pipe n of fire-clay, the peculiar construction of
which with a view to preventing the entrance of solid matter therein will be
readily understood on referring to the enlarged sectional details at Figures 4
and 5. These exit pipes (there being one in the centre of each retort)
communicate with the condenser o, whence the uncondensible gases ascend by
a passage p to a pipe or pipes p¹ leading to the atmosphere. This upright
pipe pl not only serves for the exit of the uncondensible gases, but being a
heated column produces also a sufficient diminution of atmospheric pressure to
prevent the escape of the zinc vapours outwards from the condenser and the
retorts. 111 is a
stoppered opening for the introduction of a rod or bar into
the passage, through which the residium passes from the retorts with a view
to clearing the same in case it should become clogged up; other covered
openings a, a', are made in the top of the ore chamber d for facilitating the
clearing of the retorts or the loosening of the ore therein by introducing a rod
or bar from above, the openings a' being situate over each retort for that
purpose. 9, 9, are the gas passages which communicate with the gas
regenerators 9, g¹, respectively; and r, r¹, are the corresponding air passages
leading to the air regenerators f, f. These passages 9 and r communicate
respectively with the gas mains and with the air inlet main v, a reversing
valve or regulator t, t¹, operating on the principle of a four-way cock and
worked by a weighted hand lever, serving to reverse the currents of air and
gas at will; u is the flue leading to the chimney, and 10, w¹, are valves for
regulating or controlling the supply of gas and air respectively.
A modified arrangement of zinc furnace and retorts for the continuous pro-
duction of zinc is represented in transverse vertical section at Figure 6, the
section being taken along the line 1, 2, in Figure 7, which is a partial side
elevation and longitudinal vertical section taken along the line 3, 4, in
Figure 6. In this arrangement the retorts or pots a, a, in lieu of being
cylindrical and open at the top and bottom, are shaped somewhat similarly to
the ordinary zinc retorts used in the Silesian system, and are provided with a
lateral opening at the top and bottom for the occasional introduction of ore,

page_text: and for the continual escape or occasional withdrawal of the residium, the
bottom surface being inclined considerably to facilitate the latter operation.
The feeding hoppers are here dispensed with, the ore being pushed into
each retort from a special receptacle d', and the mouth of the retort kept
closed either by the ore itself or by a slab placed against it, as shewn in
Figure 6. The fumes are carried off by a pipe n leading from the upper part
of each retort to a pipe n' leading to the condenser o, from which the metal
is occasionally run into the usual mould; p is the exit pipe for the uncon-
densible vapours, and serves also to draw the zinc vapours from the retorts.
The several retorts a, a, are disposed side by side in two rows along the
heating chamber or furnace b, into which the air and gas enter by the
passages e or e¹, near the sides thereof, alternately from the regenerators f, g,
and f¹, g'.
Figure 8 represents a side elevation, and Figure 9 a transverse vertical
section taken along the line 1, 2, in Figure 8 of a third modification for
effecting the continuous production of zinc by the aid of a regenerative gas
furnace. In this arrangement the retorts a, a, which are open at the top and
bottom so as to admit of being charged and discharged continuously, are
place obliquely in the furnace or heating chamber. b. The mouth of each
retort is covered by a plumbago or fire-clay slab c, having an opening made
therein, and through which the zinc ore is supplied from the hopper d'. A
similar slab, which may be, of cast-iron, is fitted to the lower end of each
retort, passing out through the side of the furnace, a sliding door (c¹) being
provided for the purpose of regulating the discharge of the residium. The
zinc fumes are carried off to the condenser o by the pipes (n) situate near the
upper ends of the retorts, each pipe being provided with a stoppered orifice
(n) for the purpose of introducing a rod or wire in case of being clogged,
as shewn also in Figures 6 and 7. (¹) is a central wall forming a support
for the retorts at or near their longitudinal centres, a firm seat being formed
by ramming plastic fire-clay (introduced through the side doors (6") between
In case the
the bearing surfaces of the retorts and the supporting wall.
materials contained within the retorts should clog and cease to descend in
consequence by the force of gravity a rod of iron may be introduced from
above or from below to break up the coherent mass; or a shaft armed with
projections or prongs may be fitted up longitudinally in each retort, and be
made to rotate occasionally, or even continuously, by obvious mechanical
arrangements. f, f¹, and g, g¹, are the air and gas regenerators, from which
the heated air and gases enter the furnace or chamber 6 from side to sidę
by the passages e, c, and e¹, e', alternately, as herein-before described.

page_text: The gas for supplying the furnaces herein-before described may be generated
in the gas producers heretofore employed in connection with what is known
as Siemens' regenerative gas furnace, but I prefer to use for that purpose
the modified arrangement of producer illustrated by Figures 10 and 11.
Figure 10 is a à longitudinal vertical section of the improved producer taken
along the line 1, 2, in Figure 11, and Figure 11 is a transverse vertical
section taken along the line 3, 4, in Figure 10. This producer is more
particularly intended for the use of caking coal, for which purpose I employ
a stepped grate a, having wide intervals or spaces between the bars towards
the exterior of the grate, whereby facility is afforded for blocking up more or
less the ingress of air by placing small coal on the ledges of the bars, whilst
at the same time facility is afforded for inserting a fire-bar or stirrer when
the fuel requires breaking up; the upper part of the fuel or that which has
been last fed in from the hoppers b, b, rests upon the inclined dead surface c
of fire-brick, and as the distillation progresses the carbonised fuel gradually
descends along the stepped grate a and finally rests upon the smaller grated,
through which atmospheric air enters in sufficient quantity to effect the
combustion of carbonaceous matter into carbonic oxide, and through which
the ashes are free to escape; e is a water pipe for supplying water underneath
the grate, which when converted into steam rises through the fuel and assists
the combustion; the gas which is thus produced in the chamber ƒ passes off
to the gas stack or rising column g, which may be made to receive the gas
from two or more separate producers, as shown in Figure 11, so that any one
of the producers may be shut off by the introduction of a sliding damper
at (h) for the purposes of repairs without stopping the working of the
regenerative furnace or furnaces. From the gas stack y the gas is conveyed
towards the furnace or furnaces by the conduit or pipe i. I prefer in all cases to
erect the gas producers outside the works, by preference at the pit's mouth, or
which is still better in the bottom of the pit itself. By this latter arrangement
the expense of raising and transporting the fuel to the gas producer will be
saved, whilst at the same time the onward pressure produced by the rising
column of the comparatively light gas will suffice to impel the same through
horizontal culverts or channels to any required distance without the necessity
for using propelling or forcing apparatus. This arrangement will be found
specially advantageous in old mines that have been worked out or nearly so,
and which invariably contain large quantities of refuse or waste coal dust
which is not well suited for use as fuel by the ordinary means for effecting
.combustion, and consequently is not worth raising to the pit's mouth, but which
answers well as a gas-producing agent in my gas producers. A large number

page_text: of gas producers may be arranged in a double row within tunnels or
galeries at the bottom of the coal mine discharging the gas into a common
gas shaft and culvert for the supply of one or several works. The gas
producer may also be so arranged as to conduce materially to the ventilation
of the mine.
Figure 1 on Sheet 2 of my Drawings represents a longitudinal vertical
section taken along the line 1, 2, in Figure 3 of my improved arrangement
of furnace as adapted to the melting of steel; Figure 2 a transverse
vertical section of the same taken along the line 3, 4, in Figure 3, and
Figure 3 is a sectional plan of the arrangement taken along the line 5, 6, in
Figure 1.
a, a, are the melting pots placed, as shown in Figures 2 and 3, in two
longitudinal rows of four in each division of the furnace or chamber b, which
is divided by the arch c and covered by the removable lids or covers d, d.
The floor of the melting chamber is covered by a layer of coke dust, so that
any metal flowing thereon through the accidental fracture of a
pot remains in
a fluid state by taking up additional carbon, and can be removed by tapping
at y. The coke also prevents adhesion of the pots to the bottom of the
chamber. The pots I use are not perforated at the bottom in the usual
manner, but completely closed at that part; they are also made somewhat
broader at the base than usual.
To enable these furnaces to withstand the intense heat generated therein
the walls of the heating chamber should be built of the best silica. brick, and
in order that the rebuilding of such heating chamber may be readily and
economically effected when required I construct them quite distinct from
the brickwork of the regenerators, so that they may be removed and
replaced without interfering with the rest of the furnace. A series of
recesses e, e, and e¹, e¹, are made in each. side of this chamber which
communicate with the air and gas regenerators f, g, and f, g, situate
on opposite sides of the chamber and worked alternately in the well-known
manner. These recesses may be made either directly opposite each other,
as shown in the Drawing, or the openings on one side may be opposite the
intervening spaces on the other side; they may also be so disposed as to cause
the flame to infringe directly upon the pots, or to direct the flame between
and around the same, both which arrangements are illustrated in Figure 3.
The heated air from the air regenerators for fl in its way to the furnace or
heating chamber passes above the heated gases from the gas regenerators
or g', in order that the gas which is lighter than the air may by its tendency
to rise become more intimately admixed with the stratum of air above it just
11

page_text: previous to their entering the furnace or chamber b. This mixing action is
further accelerated by contracting the gas orifices i, ¹, and by directing the
currents upwards amongst the currents of air, as shown clearly in Figures
2, 4, and 5, Sheet 2 of my Drawings. The successful working of the furnace
greatly depends upon the adjustment of these orifices. The foot plate and
parts surrounding the furnace are ventilated so as to keep down their
temperature, by constructing a vault m in free communication with the
atmosphere at one end underneath the floor of the furnace, and allowing of a
free circulation of cool air therethrough, such air passing by one or more
conduits (Figure 1) into an air space left immediately underneath the foot
plate, whereby it is kept at a comparatively low temperature. Vertical air
passages o, o, (Figures 2 and 3,) are also made in the sides of the furnace
through the iron. plate p which supports the floor for the same purpose,
such passages communicating at the bottom with the cool air chamber m,
and at their upper ends with the air spaces immediately beneath the
foot plates, which spaces are in connection with an air stack or stacks;
9, q, are the passages through which the gases alternately enter the gas
regenerators g, g¹, and r, r¹, are corresponding passages for the admission
of air to the respective air regenerators f, f¹. The gas passages both com-
municate with the gas main s, a reversing valve t constructed so as to operate
on the principle of the four-way cock serving to open one of the two gas
passages to the main, whilst the other is at the same time opened to the
flue u leading to the chimney. A precisely similar arrangement of reversing
valve is applied to the air passages r, r, at their junction with the air
inlet v, and these reversing valves may be worked by rods and weighted levers,
as shown in Figure 1, thro' an opening left for that purpose in the
foot plate; w, w¹, are mushroom valves also worked from the foot plate,
whereby the amount or relative proportions of gas and air entering the
regenerators may be regulated to the greatest nicety, and the temperature and
nature of the flame varied accordingly; x is a damper in the flue u for
controlling the draught.
Figures 4 and 5 represent in vertical and horizontal sections a mode of
strengthening the heating chamber or furnace b when of large dimensions,
by building the side walls in the form of horizontal arches in lieu of perfectly
straight, as in Figure 3. In this modification provision is made for the
reception of 24 pots, arranged in six transverse rows of four pots each, but
the length of this, and indeed of all the furnaces herein-before described,
may be increased indefinitely by simply adding to the length of the regenerators
and to the air and gas channels below, it being a chief feature of this con-

page_text: struction that each retort or crucible or file of crucibles is heated by a
separate branch of the heating gases. As it is essential to the efficient and
economical working of my improved steel melting furnace that the heat. be.
maintained constantly at or near a uniform temperature, and as this tempera..
ture would be liable to fracture the pots when first introduced to take the:
place of those damaged by usage, it is requisite that means be provided for
effectually annealing or gradually heating up the pots to a proper temperature
(say a white heat), so that they may be introduced with safety into the melting'
furnace with little or no risk of fracture. For this purpose I employ the simple.
and effective form of gas muffle shown in transverse vertical section and sectional
plan at Figures 6 and 7 (Sheet 2). b, b', are two annealing chambers, in
which are placed the pots or crucibles to be annealed or heated up preparatory
to their being introduced into the melting furnace; f, f¹, are two regenerators.
to which atmospheric air is supplied alternately by the four-way valve or
regulator at g through the passage h or h¹, as the case may be, the second:
regenerator being at the same time connected to the chimney flue u.
The
gas is conducted by the conduit i to the gas chamber k, from which a
T-passage conducts the gas to one or other of the annealing chambers b, b¹.
according to the direction of the hot-air current; m, m', are passages which
serve alternately for the admission of the hot air, from the air regenerator to
one or other of the annealing chambers, and for the exit of the products of
combustion through the second regenerator to the flue u leading to the
chimney. It will thus be seen that whilst one chamber 6 is being heated up
by the mixture of air and gas entering therein at 1, the other b¹ will be
sufficiently cool for the reception of fresh pots, and so soon as the pots in the
heated chamber 6 are sufficiently hot the current of air is reversed by the
valve and caused to pass through the chamber last heated and to enter
the newly filled chamber 6¹ in company with the gas, the operation being thus
continuous and admitting of the same uniform distribution of heat as described
in reference to the steel melting furnace.
Figure 8 represents a plan and partial horizontal section taken along the
line 1-2, in Figure 9 of a steel ingot furnace constructed according to my
Invention; Figure 9 is a longitudinal vertical section of the same taken
along the line 3-4, in Figure 8; and Figure 10 is a transverse vertical
section through the heating chamber or furnace and regenerators taken along
the line 5-6, in Figure 9. The floor of the furnace is inclined, as shown in
Figure 9, with a view to the running off of the cinder or slag at the tap-
hole y, and in order to obtain greater strength and solidity the openings
through which the ingots are introduced into and removed from the furnace

page_text: are formed by cross arches, as shown at z, z, in the Drawings. n, n, repre-
sent air channels for the purpose of ventilation; the rest of the parts, which
correspond to those in the previously described Figures on this Sheet of
Drawings, are indicated by corresponding letters of reference. It is obvious
that this furnace is applicable to the heating in a uniform manner from end
to end long and heavy forgings, such as large shafts, ordnance, &c., in.which
case the cross arches z would be dispensed with, and the forging lowered
bodily into the heating chamber.or trench, and removed again by suitable
tackle. The moveable roof of the furnace may in this case be made of one
piece of arched boiler plate lined with brickwork, to be removed where
required by mechanical agency.
Having now described and particularly ascertained the nature of my said
Invention, and the manner in which the same is or may be used or carried
into effect, I would observe in conclusion that what I consider to be novel
and original, and therefore claim as the Invention secured to me by the
herein-before in part recited Letters Patent is,-
Firstly. Arranging pots, retorts, or tubes in furnaces for the distillation of
zinc so that they can be continuously (or at frequent intervals) charged
at their upper and discharged of residue at their lower extremity, while
the vapours of zinc are withdrawn also continuously, either per ascensum or
per descensum.
Secondly. Adjusting the working of each retort or set of retorts separately
by means of a regulated orifice at the lowest extremity, through which
the residue passes away in the manner of an hour glass, the retort or retorts
being kept supplied with fresh ore by gravitation from a hopper.
Thirdly. Collecting the zinc vapour from several or all the zinc retorts
employed into a general condenser, whence the uncondensible gases mixed
with them are allowed to escape through a flue or channel leading upwards,
and by virtue of the hot column thus produced cause the zinc vapours to be
drawn from the retorts to the common condenser, whence the fluid zinc is
occasionally removed by tapping.
Fourthly. Effecting the heating of these upright or slanting zinc-retorts,
pots, or tubes by a "Siemens' regenerative gas furnace" of such particular
arrangement that the heated gases and heated air enter the combustion
chamber alternately upon the one side and the other of the oblong chamber
containing any desired number of retorts, pots, or tubes arranged in double
rows or in groups, the object being to expose each of them to the same
uniform heating action.
Fifthly. Constructing regenerative gas furnaces for the melting of cast steel

page_text: or other metal in such a manner that the pots containing the metal are
arranged in single, double, or multiple file in an oblong sunk chamber covered
by moveable roofs, or lids, and are acted upon by the heated gases entering
the oblong sunk chamber alternately from the one side and the other from a
series of niches or mixing chambers, care being taken that in each niche a
fractional current of heated gas passes in under a fractional current of heated
air to effect the combustion, the object being to expose each pot or each file
of pots to precisely the same heating action, in order that the metal may in
each of them be ready for pouring at the same time.
Sixthly. The auxiliary arrangement of a gas muffle, substantially as herein-
before described and illustrated at Figures 6 and 7, Sheet 2 of the
accompanying Drawings, for providing and maintaining a stock of highly
heated pots, which makes it possible to work the steel furnace in a continuous
manner without periodically abating its heat to effect a change of pots.
Seventhly. Constructing sunk furnaces of a similar construction for heating
metal ingots, shafts, or large forgings uniformly from end to end, as described
in reference to Figures 8, 9, and 10 (Sheet 2) of the accompanying Drawings.
In witness whereof, I, the said Charles William Siemens, have to this
my Specification hereunto set my hand and seal, this Third day of
September One thousand eight hundred and sixty-six.
Witness,
J. A. HEAD,
3, Great George St.,
Westminster,
London, S.W.
C. W. SIEMENS. (L.S.)