IMPROVEMENTS IN APPARATUS CONNECTED WITH SMELTING OF METALS AND METALLIC ORES, ESPECIALLY THE SMELTING OF ZINC FROM THE ORES AND THE PREVENTION OF LOSS OF ZINC DURING THE PROCESS."
Year: 1876

page_text: LETTERS PATENT to Androw Linmero Dowie, of Edinburgh, North Britain,
and of Barnes, in the County of Surrey, Chemical Metallurgist, for the
Invention of "IMPROVEMENTS IN APPARATUS CONNECTED WITH SMELTING OF
METALS AND METALLIC ORES, ESPECIALLY THE SMELTING OF ZINC FROM THE
ORES AND THE PREVENTION OF LOSS OF ZINC DURING THE PROCESS."
PROVISIONAL SPECIFICATION left by the said Andrew Linmerc Dowie at
the Office of the Commissioners of Patents on the 5th May 1870.
"
ANDREW LINMERE DOWIE, of Edinburgh, North Britain, and of Barnes, in tho
County of Surrey, Chemical Metallurgist. IMPROVEMENTS IN APPARATUS CON-
NECTED WITH SMELTING OF METALS AND METALLIC ORES, ESPECIALLY THE SMELTING
OF ZINC FROM THE ORES AND THE PREVENTION OF Loss OF ZINC DURING THE
PROCESS."
My Invention relates,―
Firstly. To the construction and arrangement of apparatus for burning fucl.
Secondly. To a simple and effective means of introducing steam under or above
the grate bars, into the furnace.
Thirdly. To fixing open tanks or water holders under the furnace so as to be
acted upon by the waste heat and the steam carried by the ordinary draught of
air through the grate bars into the fire chamber. The grate bars are constructed
upon the principle of a honeycomb, having a series of cones so as to form the
bottom portion of the grate in the furnace.
In order that some of the advantages of my Invention may be more clearly
understood it is necessary to state that great difficulties have been experienced
hitherto in the proper distribution of heat in large furnaces, and more especially
those used for the smelting of metals from the ores where a number of retorts or
crucibles are arranged one above the other. To meet this difficulty, when necessary
I shut off the introduction of the draught of air through the furnace bars by an
air-tight door over the lower entrance where the water holders are arranged, and
as it is the principle of steam to ascend and remain on the top of the water the
steam becomes more heated now that the water holders or tanks are shut up from
the current of air passing over them and of greater volume from the heat being
more concentrated upon the water vessels. To meet this increase of steam I open

page_text: one or more air flues in different parts of the furnace, so constructed as to form a
natural vent or air flue for feeding the furnace with fresh air under the different
ranges of retorts or crucibles where the metal is undergoing the process of smelting,
and these air funnels or vents have openings also to enable the operator to examine
the state of the furnace for feeding and shut off or introduce the air or steam at
the proper time or place required.
Fourthly. To an arrangement of retorts or crucibles for the smelting of metals
and from tho ores. They are made in the form of a or diamond shape or angled
sides, the top being rounded or otherwise formed. The retorts are open at both
ends, and are so constructed as to be fitted with moveable ends or lids at each end
of the retort, and so arranged as to have apertures for the escape of the gases that
are generated in the retorts or crucibles during the process of smelting from the
ores and for drawing off the metals when smelted. When in practical operation in
the furnace these retorts are stretched right across the fire chamber or furnace
right through the wall or building of the same, leaving both ends of the retorts
exposed for removing or drawing off the metals and gases and filling in the ores,
and for the better cleansing out of any foreign substance that may adhere to the
retorts or obstruct the process of smelting, and for other necessary work required
from the formation of these retorts or crucibles which can be made of any of the
clays or materials now in use for that purpose. They are much stronger, and
present a larger surface to the action of the fire, and allow the heat to ascend more
freely in the furnace when a number of them are at work together, besides, much
less clay and other material is required in their production although holding the
same amount of mixed ores or metals as others now in use.
The ends or lids for the retorts may be made of the same materials as the retorts
or crucibles, or of cast iron lined inside the flange with clay or other suitable
substance, or of any kind of metal or other material that may be or is now applied
for such purposes. They are formed with a solid flat flange all round the form of
the diamond so as to joint with the retort at each end with an open aperture or
opening at the one end for drawing off the metals, and at the other or upper end
for a nozzle which may be attached to or introduced or inserted through the lid for
the purpose of carrying off the gases during the process of smelting from the ores.
While the retorts or crucibles are in operation the ends or lids are to be luted with
common clay or other suitable substance.
The Invention relates, fifthly, to apparatus for the saving of the loss of zinc
during the process of smelting from the ores.
It is necessary to state that all retorts hitherto have been made with only one
open end for filling in the ores, burning of the gases, working off and drawing off
of the metals and other work required. The retort is placed in a kind of angled
horizontal position, and it is at the lower end that all the work is done. To obviate
this difficulty, and to obtain the best results from the varying circumstances, I
have made my retorts open at both ends as stated, so that when placed in position
in the furnace and the lower end or lid has been fixed by clay or some other
substance, and an iron strap or other fixture is placed over the end to keep in
position, the ores are filled in from the other or upper side, and when ready the lid
or end having the nozzle is fixed, and by attaching a tube so constructed as to fit or
joint on to the nozzle at the upper end of the retort the gases are carried by this
tube or syphon down into a reservoir partly filled with water, where all passes
through, so that all the solid particles are there detained, whether metal or other-
wise. The tube by preference 1 make like a syphon, so that during the two first
hours or so of the process the coal gas and other gases that may arise from the
chemicals used in the production pass down the one side, and when the metals
begin to smelt the oxide passing off with the gas goes down the other side, there
being a division in the tank or reservoir. When the metal is smelted it is drawn
off at the lower end of the retort, or it can be tapped and taken off as smelted at
any time during the process without in any way disturbing the working at the

page_text: other end. These reservoirs or tanks are divided in two sections, and the upper
half works on the principle of a gasometer or bellows, and by this means the gas
may be gathered to light up the works and retain any particles that might pass in
through the water.
These tubes, tanks, or reservoirs may be made of any material suitable for the
purpose of their construction, such as iron, or any kind of metal, or coarse glass, or
earthenware glazed which I prefer, or other clays which are used for retorts. Tho
tubes should be made of thin sheet or cast iron outside lined with clays glazed
inside so as not to obstruct the passage of the particles passing through them to the
reservoirs. The metal sheathing outside of the syphon or pipes is not to be on the
, on one side so that on the glazin
or clay being damaged it can bo chipped out with a chisel and again filled or
replaced anew. These tubes or syphons have stops attached so that the gases can
be passed through one or both at the same time during the process of sinclting.
By this arrangement the whole of the gases and metals which are now lost will bo
saved, and the zinc conveyed to the reservoirs will be of a higher value, besides
the saving of the other materials in this arrangement now entirely lost to the
producer by the present process of smelting zinc from the ores.
principle of a common tube, but open thus, U
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Andrew Linmere Dowie in the Great Seal Patent Office on the
4th November 1876.
ANDREW LINMERE DOWIE, of Edinburgh, North Britain, and of Barnes, in tho
County of Surrey, Chemical Metallurgist. "IMPROVEMENTS IN APPARATUS CON-
NECTED WITH SMELTING OF METALS AND METALLIC ORES, ESPECIALLY THE SMELTING
OF ZINC FROM THE ORES AND THE PREVENTION OF Loss OF ZINC DURING THE
PROCESS."
My Invention relates,―
Firstly. To the construction and arrangement of apparatus for burning fuel
Secondly. To a simple and effective means of introducing steam under or above
the grate bars into the furnace.
Thirdly. To fixing open tanks or water holders under the furnace so as to be
acted upon by the waste heat and the steam carried by the ordinary draught of air
through the grate bars into the fire chamber. The grate bars are constructed upon
the principle of a honeycomb having a series of cones so as to form the bottom
portion of the grate in the furnace.
In order that some of the advantages of my Invention may be more clearly
understood it is necessary to state that great difficulties have been experienced
hitherto in the proper distribution of heat in large furnaces, and more especially
those used for the smelting of metals from the ores where a number of retorts or
crucibles are arranged one above the other. To meet this difficulty when necessary
I shut off the introduction of the draught of air through the furnace bars by an air-
tight door over the lower entrance where the water holders are arranged, and
as it is the principle of steam to ascend and remain on the top of the water the
steam becomes more heated now that the water holders or tanks are shut up from
the current of air passing over them and of greater volume from the heat being
more concentrated upon the water vessels. To meet this increase of steam I open
one or more air flues in different parts of the furnace so constructed as to forin a
natural vent or air flue for feeding the furnace with fresh air under the different
ranges of retorts or crucibles where the metal is undergoing the process of smelting,
and these air funnels or vents have openings also to enable the operator to examine
the state of the furnace for feeding and shut off, or introduce the air or steam at the
proper time or place required.
Fourthly. To an arrangement of retorts or crucibles for the smelting of metals

page_text: and from the ores. They are made in the form of a ✓ or diamond shape or angled
sides, the top being rounded or otherwise formed. The retorts are open at both
ends, and are so constructed as to be fitted with moveable ends or lids at each end
of the retort, and so arranged as to have apertures for the escape of the gases that
are generated in the retorts or crucibles during the process of smelting from the
ores, and for drawing off the metals when smelted. When in practical operation in
the furnace these retorts are stretched right across the fire chamber or furnace right
through the wall or building of the same, leaving both ends of the retort exposed
for removing or drawing off the metals and gases, and filling in the ores, and for the
better cleansing out of any foreign substance that may adhere to the retorts or
obstruct the process of smelting, and for other necessary work required from tho
formation of these retorts or crucibles, which can be made of any of the clays or
materials now in use for that purpose. They are much stronger, and present a
larger surface to the action of the fire, and allow the heat to ascend more freely in
the furnace when a number of them are at work together, besides much less clay
and other material is required in their production, although holding the same
amount of mixed ores or metals as others now in use.
The ends or lids for the retorts may be made of the same materials as the retorts
or crucibles, or of cast iron lined inside the flange with clay or other suitable
substance, or of any kind of metal or other material that may be or is now applied
for such purposes. They are formed with a solid flat flange all round the form of
the diamond, so as to joint with the retort at each end, with an open aperture or
opening at the one end for drawing off the metals, and at the other or upper end
for a nozzle, which may be attached to or introduced or inserted through the lid for
the purpose of carrying off the gases during the process of smelting from the ores.
While the retorts or crucibles are in operation the ends or lids are to be luted with
common clay or other suitable substance.
The Invention relates, fifthly, to apparatus for the saving of the loss of zinc
during the process of smelting from the ores.
It is necessary to state that all retorts hitherto have been made with only one
open end for filling in the ores, burning of the gases, working and drawing off the
metals, and other work required. The retort is placed in a kind of angled horizontal
position, and it is at the lower end that all the work is done. To obviate this
difficulty, and to obtain the best results from the varying circumstances, I have my
retorts open at both ends, as stated, so that when placed in position in the furnace,
and the lower end or lid has been fixed by clay or some other substance, and an
iron strap or other fixture is placed over the end to keep it in position, the ores are
filled in from the other or upper side, and when ready the lid or end having the
nozzle is fixed, and by attaching a tube so constructed as to fit or joint on to the
nozzle at the upper end of the retort the gases are carried by this tube or syphon
down into a reservoir partly filled with water, where all passes through, so that all
the solid particles are there detained, whether metal or otherwise. The tube by
preference I make like a syphon, so that during the two first hours or so of the
process the coal gas and other gases that may arise from the chemicals used in the
production pass down the one side, and when the metals begin to smelt the oxide
passing off with the gas goes down the other side, there being a division in the
tank or reservoir. When the metal is sinelted it is drawn off at the lower end of
the retort, or it can be tapped and taken off as smelted at any time during the
process without in any way disturbing the working at the other end. These
reservoirs or tanks are divided in two sections, and the upper half works on the
principle of a gasometer or bellows, and by this means the gas can be gathered to
light up the works, and retain any particles that might pass in through the water.
These tubes, tanks, or reservoirs may be made of any material suitable for the
purpose of their construction, such as iron or any other kind of metal, or coarse glass,
or earthenware glazed, which I prefer, or other clays, which are used for retorts.
The tubes should be made of thin sheet or cast iron outside lined with clays glazed

page_text: inside so as not to obstruct the passage of the particles passing through them to
the reservoirs. The metal sheathing outside of the siphon or pipes not to be on
the principle of a common tube, but open on one side, so that on the glazing or clay
being damaged it can bo chipped out with a chisel and again filled or replaced
anew. These tubes or syphons have stops attached, so that the gases can be passed
through one or both at the same time during the process of smelting. By this
arrangement the whole of the gases and metals which are now lost will be saved,
and the zinc conveyed to the reservoirs will be of a higher value besides the saving
of the other materials in this arrangement now entirely lost to the producer by the
present process of smelting zinc from the ores.
It will be obvious that these improvements comprise various modifications of
detail and arrangement to suit the different and necessary circumstances under
which the apparatus is employed for the burning of fuel, the introducing of steam
and air into the furnace, the utilizing of the waste heat, and in the construction
and arrangement of the retorts or crucibles; also in the construction or fitting of
or in the mode of applying or attaching such apparatus for the prevention of loss
of said metals during the process of smelting and from the ores.
Having explained the nature, and in order that my said Invention may be fully
understood, I shall now proceed more particularly to describe the same.
I may state that considerable difficulties are known to exist in the production of
various metals and metallic alloys, and other compounds suitable for commercial and
manufacturing purposes.
The furnaces heretofore or as now used for the smelting of metals in crucibles
are in many ways unsuited for the smelting of metallic alloys and other compounds,
which vary so much in their nature when under the process of fusion.
In the ordinary well or pit furnace or bullion furnace serious obstructions and
other annoyances daily occur from the unequal combustion of the fuel and a want
of the proper distribution of the heat required being applied to the crucible when
under the process of smelting metals or metallic alloys or other compounds.
Crucibles while at work in the fire-chamber are partly or wholly embedded in the
fuel, thus producing chemical influences upon the metal, and metals undergoing the
same process in the fire of the air furnace aro being acted upon by the fuel in a
similar manner, and according to the nature and quality of the fuel used it plays a
very important part in the production of the metals now in usc. There is also
a considerable loss of the metal in producing such alloys or compounds from
one or other of the causes referred to, the metal being often porous or brittle by
being overheated or by not being properly fused; bad castings are the result,
incurring loss of labour, time, and material.
Having thus so far referred to some of the disadvantages, connected with the uso
of the pot or crucible furnaces for producing the various metals or metallic com-
pounds of commerce, such as steel, bullion, nickel, copper, bronze, brass, zinc, and
other compounds varied in their nature and chemical properties, arising from the
difficulties of combustion of fuel and the smelting of different metals in one and
the same chamber or otherwise, as heretofore. In practical operation, to obviate
this difficulty and to obtain the best results from such varying circumstances, I
have, in carrying my said Invention into effect, which relates, firstly, to the con-
struction and arrangement of apparatus for burning fuel, provided a construction
different in principle and in its arrangements and apparatus from any other
hitherto in use for the smelting of metals, metallic ores, and other chemical
compounds.
The said Invention, firstly, relates to a furnace or furnaces having one or more
fire-chambers for the combustion of fuel and a series of chambers or compartments
for the smelting of metals and of metallic ores, they being so acted upon by the
fuel that different degrees of heat are produced in the smelting chambers, suited
to the varied requirements of the metal or metals or other compounds undergoing
process of smelting or fusion. To obtain this I have placed the furnace or
the

page_text: "1
largest fire-chamber lowest down in the centre of the construction. The interior
should be lined with fire-stone or what is called "bosh or hard fire-brick, tho
throat, or flues, or feeders on each side for conveying the heat into the sinelting
chambers should be slightly rounded off, so as to prevent any sharp angle obstruct-
ing the passage of the fuel. The bottom of the furnace is composed of the grate
bars herein-before described, upon the principle of a honeycomb or series of hollow
cones, or of any other construction or form having the apertures or orifices smaller
on the face of the grate bars than the bottom when in position or placed.
The tanks or water holders 1 prefer to range along each side of the ash-pit,
running the same length along as the grate bars of the furnace. The best form of
construction suitable for the tanks or water holders is that where the greatest
amount of waste heat from the furnace and ash-pit can be brought to bear upon
them for the production of the steam, and for the free passage of the waste fuel
through the fire-bars to the ash-pit.
The upper portion of the furnace is composed of large fire-stones or fire-bricks
luted with clay, so as to be removed when more direct or greater heat is required.
The side chambers on each side of this furnace for sinelting metals are lined with
fire-bricks, having a moveable fire-brick bottom, so constructed that on their
removal fire or grato bars are inserted, thus giving a range of fires, if greater heat
is required for the smelting of any metals or from the ores. The upper portions of
these side chambers or furnaces are arranged so as to form muffle or assay chambers.
The centre chamber for smelting right over the centre or large fire is constructed
and arranged for smelting metallic ores or other metals or compounds required for
large castings or otherwise for chemical compounds, and to give greater volume
where more intense heat is needed I shut off the introduction of the natural
draught of air through the furnace bars in one or more of the fire chambers, and
open one or more of the flues or vents referred to in different parts of the chambers
under the ranges of retorts or crucibles. Under this arrangement an intense
white heat can be maintained or a low dull red heat for any length of time
necessary to the operation in hand, and different degrees of heat in the different
chambers for smelting suited to the different metals can also be supplied; further,
there are openings for looking into the furnace or series of chambers to enable
the operator to regulate the heat required, and for the saving apparatus being
applied for the prevention of loss of metallic ores or other compounds during the
process.
It will also be observed that the chemical influences of the fuel are in great
measure prevented from operating upon the metals.
Fourthly. My improvements relate further to an arrangement of retorts and
crucibles for the smelting of metals, metallic ores, and other compounds required for
commercial purposes. These retorts and crucibles being from their construction and
formation diamond or angled shaped or having angled sides, and being open at
one or both ends, are fitted with a new arrangement of apparatus for the saving of
the loss of metals under fusion and during smelting of metallic ores, especially the
smelting of metallic compounds, and more especially the smelting of zinc from the
ores, and the prevention of loss of zine during the process; said retorts or crucibles
are so arranged as to have also apertures for carrying off the gases, oxides of metals,
and other chemical compounds as they are generated in the retorts or crucibles into
the reservoirs fitted with moveable apparatus for the saving of the same.
Retorts and crucibles constructed on my principle have many advantages over
any others heretofore in use. From their formation they receive the greatest amount
of heat under operation from the fuel and metallic ores, and all other metals are
smelted by them in a much smaller space of time. The diamond or angle form
gives greater strength and durability; the retorts with two moveable ends or lids
save time in filling in the ores and other compounds, and any foreign matter can be
easily removed. Metals can be drawn off without disturbing the saving apparatus
when smelting metallic ores, and more especially the smelting of zinc from the

page_text: ores; they are also of great value for smelting all kinds of metals and other
chemical compounds, and in the furnace the greatest strength combined with the
required degree of heat is obtained.
My Invention relates, fifthly, to apparatus for the saving of the loss of metals
and metallic ores, and for the saving of the loss of zinc during the process of
smelting from the ores, as herein-before described.
I have provided in accordance with my said Invention another mode of this new
arrangement of apparatns for the saving of the loss of metals during the process
of smelting. In cases where furnaces for the smelting of ores already exist having.
only one side exposed for the various operations of producing zinc and other metals
from tho ores, and where spaco cannot be obtained for working the retorts open at
both ends, although I prefer that modo. to all others when smelting from the ores
for the saving of labour and material and to suit this class of furnace, I construct
retorts on my principle open at one end with a moveable lid or door with apertures:
for drawing off the metals, and stirring the ores. These retorts have also one or
more openings as required on the upper end or angle when in position for admitting
or fixing or attaching the tube or nozzle, whereby the gases aro carried into a.
receiver or reservoir. These pipes or tubes are made of several sections having
joints on the principle of a bayonet joint, so as to be easily fixed or removed in
whole or in part as required, and may be used single. The receivers or chambers
can be of the most simple description of formation, and instead of being partly.
filled with water may be dry, having only one receptacle or chamber for the recep-
tion of all the gases passing from the retorts through the tubes into the receiver,.
and instead of being constructed with bellows or on the principle of a gasometer, ns:
herein-before given in the former example or mode of saving the loss of zinc during :
the process of smelting from the ores, that is to say, that such receiver can bo
made in the form of a cylinder or otherwise; they are to be air-tight, and of
sufficient size for holding the products from one furnace during the whole process
of smelting a shift of the ores. The tubes attached to the nozzles of the retorts I
pass through water, or the cylinder may be immersed in-water, so that the tubes
pass through it before the gases enter the receiver or cylinder. I now open one or
more apertures in the top end of the cylinder, and insert one or more pipes for
carrying off the gases from this chamber into a pit or reservoir partly filled with
water, through which the gases all now pass. This pit or reservoir I construct on
the same simple plan of the cylinder now described, with tubes or pipes inserted
for carrying off the gas to be stored or burned as generated.
When the gas is to bo used to light up the works I prefer to pass the gas
through some animal substance, such as wool or hair. This I simply do by fitting
some into the pipes through which the gas passes after having gone through the
water in the pit or reservoir, which may be made suitable to receive the gases from
one furnace, or so constructed as to receive the gases from each of the cylinders of
the whole number of furnaces in the works. Where the gas thus gathered is not
of proper quality to give light it can be passed into the air flues or water holders
to be burned with. the fuel of the furnace, or this last operation can be passed.
through the water in an open tank or reservoir, and the gases after passing through
the water allowed to escape in the air.
By this improved construction of apparatus something like 25 per cent. of the
zinc now lost will be saved during the process of smelting from the ores and the.
oxides of other metals, and chemical compounds now lost can be gathered and saved.
under the same arrangement, besides the metals are greatly improved in quality by
being saved from mixing with other chemical influences from the fuel, and one or,
more of these single end retorts can be used to manufacture gas for the work
where the gas produced is not or cannot be used for that purpose.
.
The accompanying Drawings illustrate the sections of my retorts, and the manner,
of placing them in the furnaces or "setting," as also the arrangements of appliances
by which the gaseous funies are drawn off, and their solids deposited, in addition to.

page_text: the shape of the furnace bars and water tanks by which the intense heat is main-
tained for the purposes of my Invention.
A, Figure 1, represents a sectional view of part of a furnace bar; and Figure 2,
a plan of sufficient of a couple of them to show how I make the conical apertures
in alternate order for the passage of the air and the steam from the ash-pit, which
commingle in passing through the steam coming from slits a, a, in one or more
water chamber or tanks B, B, which are placed or built in and form part or side
walls to the ash-pit, as in Figure 3, which is a transverse section of a 'setting
complete C, C, are vent pipes by which atmospheric air is admitted to the com-
partments D, E, F, etc., as desired, in order to regulate the heat therein, and to
keep it uniform, the flame and products of combustion passing into the same
chamber through sido apertures b, b, as shown by the arrows.
"
Figures 4 and 5 are modified shaped passages in the fire-bars, the passages in
these, as in the former case, being larger at the bottom than at the top.
Figure 6 represents a transverse section of a "setting" with the air vent C, C, ns
part of the structure, and with additional water chambers or tanks G, G, as
side walls to other compartments, which may be fitted with furnace bars if
desired.
Figure 7 represents a "setting" of four of my improved shaped retorts; and
Figures 70 and 7b, modifications thereof. The two on the left marked H, H, of
Figure 7 are open retorts to which a door can be fitted at each end to close them
up, as in Figure 8, the sight and stirring holes o, b, being at the top of one end,
and the drawing-off holes c at the bottom at the same end, and the saving apparatus
is attached to or inserted into the upper end when in position. The next marked I
and J are closed each at one end like an ordinary retort, as in Figure 9, the opposite
end only having a door fitted, in which the sight or stirring holes band the draw-
off holes c are arranged, as shown.
Figure 8 is a view partly in section of an improved shaped open-ended retort, to
which a door is fitted at each end, one of the doors having the branch Kattiched,
by which the gaseous fumes are permitted to pass into a receptacle L, in which the
metallic particles become condensed and deposited, the gas proper going away by
the pipe e.
In Figure 9 I have shown the fumes' pipe as fitted in the top of the retort instead
of in the end cover, so as not to disturb working operations.
Figure 10 shows a setting with a furnace arranged transversely to the length of
the retort that the flame and products of combustion may strike the retort bottoms
in succession while on their way to the flue. This plan, on account of the spaces
between the angular walls of the retorts ensures a complete expansion and action
of the beat upon their upper surfaces to cause an equal temperature within the
retorts.
The retort shown in this Figure (10) is at an angle with the sight and drawing-
off hole in one end cover, which end is at a lower elevation than that of the other
or fumes' pipe end, in the aperture of which a nozzle, shown detached in Figure 11,
may be fitted; this nozzle end has in connection a syphon or double legged pipe,
down one leg of which the gas from the retort can pass, and the metallic fumes
which escape from the retort down the other g, as in Figure 12. Both legs are
provided with slide taps, so that either of them can be shut off as desired. The pipes
g, are enveloped or nearly so by a shield or casing, as in Figure 13, to prevent the
too sudden action of the atmosphere upon the pipes.
In Figure 3 I have shown one of the "setting" chambers as furnished with
crucibles P, P, standing upon the partition, as an example of how I intend to
utilize the heat, there being a chamber Q over, in which a mufile can be placed to
facilitate assaying and other operations to be carried on if desirable. These
crucibles have angled sides with corrresponding covers, as in Figures 14, 15, 16,
which covers may each have a draw-off pipe attached, as in Figure 17, for the
separation and condensation of the gaseous and the metallic fumes which escape

page_text: from the crucible. The fumes' pipe in this arrangement passes through an opening
in the brickwork, which is kept closed by sliding doors i, j, Figure 18, or they may
bo passed through an aperture made in the door.
Having now described the nature of my said Invention, and in what manner
the same is to be performed, I declare that I claim,―
Firstly. The construction and arrangement of the parts, as herein-before described
and shown, in.or by which metals and metallic ores and other liko compounds can
be treated (smelted), especially zinc, for the purposo set forth.
Secondly. I claim the special formation of furnace bars, as set forth and shown
in Figures 1, 2, 4, and 5, especially when employed in smelting furnaces and for
retorts in conjunction with the tanks or water holders as described, so arranged as
to cause the proper combustion of fuel independently of mechanical power.
Thirdly. I claim constructing retorts with V, diamond, or angled sides, as illus-
trated by way of example in Figures 7, 8, and 9 of the annexed Drawings when
used as and for the purposes set forth.
Fourthly. I claim constructing crucibles with sides or faces at angles one to tho
other in contradistinction to circular shape in cross section and their uses, as and
for the purposes set forth..
Fifthly. I claim the method of condensing and depositing metallic fumes as they
leave the retort or the crucible, as the caso may be, whereby the saving of the usual
loss of zinc and inetals from metallic ores or .inetallic compounds is effected during
process of smelting.
the
Sixthly. And especially I claim condensing and saving metallic zinc arising from
zinc ores during the process of smelting.
In witness whereof, I, the said Andrew Linmere Dowie, have hereunto set my
hand and seal, this Third day of November, One thousand eight hundred
and seventy-six.
A. L. DOWIE. (LS.)