IMPROVEMENTS IN THE SEPARATION OF ZINK FROM OTHER METALS, AND CHEMICAL COMBINATIONS AND APPARATUS APPLICABLE THERETO
Year: 1880

page_text: LETTERS PATENT to George Barker, of 77, Colmore Row, Birmingham, in the
County of Warwick, Consulting Engineer and Patent Agent, for an Invention
of "IMPROVEMENTS IN THE SEPARATION OF ZINK FROM OTHER METALS, AND
CHEMICAL COMBINATIONS AND APPARATUS APPLICABLE THERETO."
A com-
munication from abroad by Albert Harnickell, of New York, United States of
America.
PROVISIONAL SPECIFICATION left by the said George Barker at the Office
of the Commissioners of Patents on the 12th October 1880.
GEORGE BARKER, of 77, Colmore Row, Birmingham, in the County of Warwick,
Consulting Engineer and Patent Agent. "IMPROVEMENTS IN THE SEPARATION OF
ZINK FROM OTHER METALS, AND CHEMICAL COMBINATIONS AND APPARATUS
APPLICABLE THERETO." [A communication from abroad by Albert Harnickell, of
New York, United States of America.]
My Invention consists of the following processes, whereby I produce cheaply, on
a commercial scale, the chemically pure and dense zinc heretofore only produced at
high cost in the laboratory, making the same now economically available to the
arts and manufactures.
Taking as my raw material the ordinary spelter of commerce, or any impure
zinc, I smelt the same by a method which involves new features. This first stage
of my total operation removes the grosser and larger portions of the foreign and
nonzinc elements in the commercial or unmerchantable zinc, such as iron, silver,
lead, arsenic, antimony, etc.
This measurably purified zinc I then subject to an entirely new process of
distributive or selective distillation aided by the novel apparatus presently to be
described, whereby I eliminate all the residue of non zinc elements in this part of
my process, making the novel use of the physical fact that the various impurities
which can be volatilized at furnace heat, condense at a lower temperature than the
zinc itself, of winning the zinc separately, and the other elements separately, all
without access of air.
In the last place I employ as a finale of measure, taken during the former

page_text: process, to promote molecular compactness as well as purity, a casting process for
the purified zinc, by which I produce it in the densest possible condition.
And the consequence of this chain of processes in the production of pure zinc in
the chemically and physically appropriate condition of a much higher specific
gravity and tensile strength than that of any zinc hitherto produced in any, except
purely scientific laboratory experiment, whereby this product is rendered of great
value to the arts in the commercial sense.
I proceed to describe first the process which I employ and recommend for smelting
the impure zinc, and I would here draw attention to the fact that this process
stands at the outset, and as the first link in the chain of the total process, whereas
heretofore in zinc metallurgy, the refining portion of the work, which for convenience
I call the smelting (or the kettling) process, has been performed after and not
before distillation.
I take then ordinary or impure zinc or zinc dross, and simply melt it to dull red
heat in the reverberatory zinc furnace, or in a muffle or in a kettle to settle, and
remove lead in the usual way; if present in quantity, it cannot all be removed in
this way.
After removal of such lead I plunge to the bottom of the bath sulphur
in an iron pipe or vessel perforated with several holes, each supplied with a wooden
plug held down by a handle, and moved about in the bath always below the
surface; the device of the wooden plugs insures for all but extremely plumbic of
ferric zinc a sufficient prolongation of the infusion of sulphur. Other reagents may
be similarly introduced to meet the case of unusual mixtures not often appearing in
commerce.
The effect of the introduction of brimstone in the presence of iron, even at the
moderate heat employed, is the formation of sulphurets, also arsenites combined of
metallic elements present, excepting the zinc, which is not touched by the sulphur.
These sulphurets mixed with some zinc are removed with the perforated ladles for
accumulation and subsequent repetition of similar treatment to liquate zinc out of
them. The bath consists now of approximately pure zinc in an electric state
unsuitable for the arts, since it contains much electro negative zinc, a kind of
allotropic condition comparatively useless for the arts, but one which invariably
attends the kettling or other rough processes of separating zinc from impurities;
and I point this out, because by my further processes in the campaign I reverse
this molecular condition, and render all the zinc electro-positive, a fact of moment
in a scientific as well as in a commercial point of view.
This part of my total process gives me the material for the further process of
distillation and casting, but not absolutely, since material not treated in this first
part, may be at once subjected to the distilling process, as for instance, silver-zinc,
leadscum, or other material with which fluxing or kettling would not be economical
practice.
I describe secondly the new and improved apparatus I have invented and
devised, and which I employ preferentially in the further processes (viz., distilling
and casting) of this new operation, of entirely separating zinc on the large scale.
From the firebox, which is supplied with air from the ashpit in the usual way,
lead the fire channels over bridge walls. The fire passes through combustion
chambers located in the retort furnaces, from which chambers it passes through
openings over the retorts, and thence through several openings on the opposite side
of the retorts into passages which communicate by means of smoke flues with the
chimney.
Suitable dampers covering the ends of the channels. Each retort chamber is
divided longitudinally by a hollow pillar wall, upon which rests the retort. Suitable
openings can be connected, and lead through openings into the firebox above and
below the grate. By these means a hot blast as it were, if necessary, may be
supplied to the firebox, or let into the retort furnaces through valves worked by the
dampers, the air being heated in its passage through the channels. This hot blast
may be used or not as desired, but these channels or hollow walls are designed in
any event to cool the masonry, by allowing air to circulate through them.

page_text: So much I premise as to the novel furnace, one of the obvious advantages of
which is, that in a retort system one or more retorts may be operated separately
from the others, the fire being shut off from all not operated.
The retort I employ, which in respect to the material of which its interior is
made, and the manner of finishing it for use is entirely novel, ensuring a physical
action, essential at least to the economy, and, as I hold, largely contributing to the
novel electro-chemical success of my process, and which features of this retort I
count one of the principal parts of my claimed improvements, and as of great value
for metallurgical purposes beyond that of this process, as well in distilling as in
melting, including the reduction of zinc from its ores.
The retort is provided with a charging lip at the one end, and at the other end
with a condensing pipe, necessary to be inclined, which leads to the receiver.
This receiver is preferably set on or into the masonry over the smoke flue.
Now, viewing the retort and condenser as parts of one apparatus I would say
that the retort is made of good fire clay. The charging lip may be of any desired
shape. The condensing channel chamber at the other end must be slightly inclined
and may have branches; it enters the receiver.
While I do not claim any particular shape for the body of the retort, yet the
general proportions are material. I prefer for wholesale work a retort 6 feet
long by 7 feet interior diameter, with condenser (and branches if any) and receiver
of proportionate size.
The retort proper is set upon the pillar wall; if it is desired to let part of the
fire play under its bottom as well as over it, a few saddles may be placed under it;
the openings opposite the spaces between the saddles must be so calculated as to
location and size as to equalize a distribution of fire or heat around every part of
the retort, counteracting the law that fire seeks the shortest way to the chimney
by taking into account volume, the same as if dealing with water under pressure.
The device employed for tempering the clay portion of a new retort before use
is, pipes or flues are made to lead respectively into the retort from the fire flue
into the smoke flue. By these means the clay portion of the retort is
heated simultaneously from without and within, greatly lessening the danger of
cracking it.
Having thus tempered the clay retort, or if made of other material than clay, at
all events heated in situ, I next proceed to a special and novel manipulation as
applied to a melting or distilling retort in metallurgy, whereby I close all pores
and fire cracks of the interior, and render the inner surface perfectly refractory or
proof against fused or gaseous metal within the retort, so that no part of such
metal can enter the substance of the so specially prepared retort. Thus I prevent
all leakage and waste, and ensure the completest pressure of the gaseous metals
and a gaseous condition therefore of the zinc itself, as I hold highly favourable in
connection with subsequent condensation and solidification to high specific gravity.
In the manipulation special of the interior surface of the retort I avail myself of
the experience acquired in making illuminating gas. In that process when a
retort is worked too long or unskillfully it is carbonized. In that process the
desideratum is to avoid as much as possible carbon deposit in the retort. I, on the
contrary, desire and aim at a deposit not of carbon indifferently, but of graphite,
not only on the bottom but on the whole interior surface of the retort, and I, in
fact, do obtain by decomposition of hydro-carbonacious material a specific carbon
lining deposit, which in its physical properties appears to be in the nature of
graphite, giving me thus a retort which partakes of the metallurgic advantages of
the graphite or plumbago crucible, only that mine is better, being solid graphite
instead of a mixture of it with clay, while the outside of my retort offers no carbon
to the oxygen of the fire gases, so that it will last indefinitely, while the plumbago
crucibles of the arts are too soon worn out by exposure to the fire.
To effect this I conduct into the white hot clay retort hydro-carbon gas,
preferentially pure, or else obtained from coal-tar, tallow, rosin, or other analogous
substance, and maintain the gas under pressure and subject to decomposing heat in

page_text: This
the retort. Small safety jets lead from the retort for the escape of the highly
hydrogenous surplus products of decomposition of the gas which are ignited. The
result of this operation after a certain time, which will obviously depend upon the
force of heat and pressure employed, as well as on the materials and skill, is that
the retort is lined or coated with carbon of peculiar graphitic character.
interior carbon-layer-lining should be preferably 1/8 to 1/4 of an inch in thickness,
though a less thickness may be sufficient. After deposit the retort should
remain for some time, not exceeding 24 hours, hermetically closed, always
under the same heat. In the case of the use of certain hydro-carbons there would
be found. if the retort were opened, floating particles of soot non-graphitic carbon;
these can be burned away, but offer no inconvenience as they will afterwards
find their way into the receiver. The retort may now be considered ready for use
by attachment of the condenser to it or of the receiver to the condenser, if the
latter was luted in before heating the retort.
Next, as to the specialities of the construction and apparatus of the condenser
and receiver. The condenser, a channel-chamber illustrated by a cylindrical pipe
(which, however, may have branches), is slightly inclined, as shown, and enters the
receiver.
This latter is of suitable external shape, and provided with a shelf extending
across the whole width of the receiver. The shelf is slightly inclined, as shown,
and should be placed nearly immediately under the opening of the condensing
channel. This shelf is perforated with an aperture as close as possible to the side
of the receiver; under the outlet of the condenser aperture should be girdled by a
small projecting fender, so as to receive the eventual zinc dropping, as hereafter
described, and pass them below without splashing.
Tapholes are formed in the receiver near the bottom and also just above the
shelf for letting out contents when desired. A water jacket is applied to the
condenser when the operation of the process has gone so far as to make it necessary
to lower its temperature. I prefer it to a sprinkler on account of the inconvenience
of creating steam.
There is a moveable pipe inserted into the side of the receiver directly opposite
the channel condenser pipe, with which it accurately registers, so as to be able to
make one continous pipe channel with the condensing pipe when pushed inwards.
This pipe is provided with a sliding rod and inner end partition plate, and also a
semicircular plate for cleaning and completely closing the pipe with an outer end
plate provided with a glass or mica window through which the phenomena in the
condenser and retort may be observed.
Next, the casting mould is made by preference of zinc, and provided with a
dip to receive the metal as it is poured, and a wide neck leading to the main
mould; on either side of the neck are notches serving as bearings for the skimmer.
On either side of the mould are pins which support it in the water or other
refrigerating bath. The skimmer is provided with lugs that rest between the
notches, the skimmer resting in the neck serving to skim the metal as it flows
under it and retain any dross or oxide. The water or other refrigerative bath
vessel should be of strong constructions so as to avoid shaking of the metal in
casting by ebullition, and the mould should be firmly fastened to the vessel.
It is obvious that this mould in toto may not always suit the purposes of casting,
this depending on the kind of work or shape to be accomplished, but for the
purpose of the general result of my process refrigeration without causing coldsets
is too desirable to allow of neglecting the precautions taught by this mould.
Having thus substantially described the apparatus, in so far it is novel and
improved, which I use in the process of distillation, separation of zinc from
impurities, and having above already fully recounted the initial preparation when
practical of the raw material, I now proceed to describe, thirdly, the distilling
process, which, combined with the mode of condensation, is a most distinctive part
of my improvements.
I have now to charge the retort with metals, if fluid through the front charging

page_text: lip, otherwise through a hopper; at this time, and at all times, care must be taken
to admit no air into the retort. As regards the composition of the charge, if the
metal has passed through the kettling or first process the impurities still in it are
in the desired physical condition; if not, a little kettling metal ought to be added,
Bince traces of iron and sulphur are useful in the retort. However, as not every
kind of alloy or mixture can be foreseen, there is no objection to a trifling admixture
of fluxes or reagents, determined by general principals of chemical metallurgy and
according to the nature of the charge. The heat of the retort is sufficient to fuse
any alloy, and probably all mechanical mixtures of zinc, and produce a fluid level
inside; accordingly the operation of charging is repeated after intervals, but so as
not more than half fill the retort, nor so quickly as to cool the inside much. The
heat in the chamber is kept at the distilling point of zinc in the retort; it is, of
course, lower during the act of filling in.
When the operation of charging the retorts begins the long pipe is pushed
through the receiver to join the condensing pipe channel, thus closing the receiver,
and leaving the movable pipe as the only outlet from the retort.
This latter may
be kept shut or set to open by a simple outlet valve to allow of the escape of
non-metallic gases, if such are expected, but air must be kept out of it, therefore
the valve should close automatically.
The result of the operation thus far is the volatilization successively according to
their points of distilling temperature of all metals in the retort volatile below the
distilling point of zinc, such as cadmium, antimony, mercury, sulphur, and combina-
tions; fixed ones remain in the retort. These pass through the condensing
channel chamber and condense in the pipe, which is cool, and are scraped towards
its rear and opening by using the scraper as explained above. The receiver is thus
kept closed until sufficient condensation of zinc itself in the pipe gives evidence of
the operation, so far as other fugitive metals are concerned, being complete. These
other metals can be saved separately if desired, such as cadmium, etc., by keeping
the pipe well cleaned of substances condensing successively prior to zinc (where
poisons like arsenic, antimony, or mercury are expected to appear in sensible
quantity their special metallurgy must dictate precautions. Where amalgam of
zinc and mercury is treated condenser and receiver bad better be of wrought iron,
and end of movable pipe in a vessel of water, the heat to be below the distilling
point of zinc, which will however distil over with the mercury in small quantity
and lodge in the receiver, in which the heat will be sufficient to continue driving
mercury into the cool pipe. The zinc gained and that remaining in the retort is
not pure and should be considered as raw material.
One salient point of difference between my process and that of ordinary zinc
winning is apparent. I have comparatively an immense quantity of zinc in the
retort, and obtain an immense pressure which 1 purposely maintain by not having
a large outlet orifice.
Recurring to the normal process, when solid or liquid zinc appears in quantity in
the extension pipe, the next thing to be done is to draw out the pipe so as to
disconnect it from the condensing channel chamber; it should be drawn through
so as to leave its end flush with the inner side of the receiver.
Now at this stage the zinc in the retort distils over, condensing in the pipe or
channel-chamber, which is heated by the great latent heat set free by the zinc in
passing from a gaseous to a liquid state, at first sufficiently and afterwards more
than sufficiently, to prevent solidification. The metal runs out of the condenser
and through the orifice in the shelf to the warmed bottom of the receiver, where it
accumulates.
At this point it is necessary to make mention of a supplementary construction
to the condensing channel chamber. The phenomena regarding beat occurring
between the retort and the receiver are that the condenser is subject to heat from
three sources, viz., 1, the clay of the retort; 2, the beat of the interior of the retort
from which it leads; 3, the latent heat of the zinc condensing around the inner
periphery. The intensity of the first two sources decreases with the distance of

page_text: any point in the condenser from the retort; the intensity of the third source is
uniform. In ordinary zinc condensing only radiation is availed of to get rid of the
heat, while I cool the outside of the condenser artificially; the immediate effect of
such cooling is upon the inner periphery, hence it is a factor bearing upon the
latent heat, leaving the two first sources of heat in the condenser as main factors in
the nice calculation for the object aimed at, viz., the maintenance of sufficient heat
in the condenser to keep fugitive impurities volatile, but not enough to keep the
zinc in a gaseous state. In a long pipe zinc and impurities would at a certain point
condense or mix together. Hence I limit the length or rather the distance of the
extremity of the condenser from the retort. But while for a moderate task the
single pipe may be sufficient, if it is desired to distil great quantities at great
speed, instead of relying on the superficial idea, that then greater retort heat would
authorize greater length of condensing pipe, it is much safer to avoid lengthening
distance from the retort orifice, and to increase the cooling surface of the condenser
by letting branches bulge out from it, radiating upwards, so that the zinc con-
densed therein shall flow into the main stem.
It will be found that any irregular product, zinc dust, oxide, and impurities will
lodge on the cool shelf and above it, or go over into the cooler extension pipe which
is open to the receiver. When the outside of the condensing channel grows red
hot only zine goes over.
At this time the water jackets must be applied around the condensing chamber
(and branches, if any) to reduce its temperature, and enable it to condense all
ascending gaseous zinc, in such wise, that it shall not be condensed in the receiver
or the extension pipe, nor run in a red hot state into the lower receptacle. At
regular intervals, and before charging again, the receiver must be tapped. The
lower taphole is opened and the lower part of the receiver emptied. The resultant
zinc is chemically pure. This must be allowed to cool without chilling until the
skin with adhering clay or dirt can be taken off with one skim. All contact
with iron or other metals should be avoided, even iron tools should not be used.
The final operation is to cast. This is done in the water mould above described.
This is previously cleaned and polished, and for castings for rolling zinc is set
slightly out of level so as to yield the usual form of plate with one surface inclined.
While this artificial cooling is prescribed for ingot and plate casting, with artistic
or hollow castings the same principle is applied, from the fact that the moulds are
thick and cool, and with my zinc, which is fluid as water, yield extremely thin
hollow castings very perfectly, and of much greater tensile strength than with any
other zinc. But the moulds must be kept cool to maintain perfect result.
By way of explanation, I would say this arrangement of the novel apparatus and
the manipulations give me chemically pure zinc, as is easily comprehended.
Were it not this pure, no pains to make it into a piece of metal of entirely
electropositive character as a whole, or of comparatively great density, would be of
any avail.
But because mine is, it is worth while to do. for it all that can be done to insure
my obtaining it in the condition of greatest density or specific gravity.
I hold that the density of zinc may be greater or lesser while in the gaseous and
in the molten, as well as while it is in the solid and in the wrought state, and that
under the precautions I have devised, the density gained in one state is not wholly
lost (as is popularly assumed) when it passes into the other state, so that with my
zinc the artizan or scientist shall, in a first use of it, be able to derive the benefit
of this novel quality of greater specific gravity than that of other (even pure) sorts
of zinc.
This then is the object of the apparently curious process rules laid down, which
are the reverse of those for zinc making as hitherto practiced, viz., to maintain
rather than relieve greate pressure in the retort; to increase it at the point of
condensation by having a narrow short outlet from the retort, presenting never-
theless, sufficient condensing surface because artificially cooled, instead of an ample
outlet and spacious condenser as at present; to remove the molten zinc thus gained

page_text: at once from the influence of further heat, instead of leaving it exposed to it or
allowing it to solidify, so as to require a remelting, both of which are the present
practices; to cool the zine if necessary down to a simply free flowing state before
casting, instead of being indifferent to it as at present; to chill it without bringing
it in contact with water at the moment of crystallization, instead of cooling
it afterwards, or keeping it warm for use, both of which are present fashions. Made
and cast in the way above indicated, the product is of high specific gravity, equal
to that of the rolled zinc of commerce, and wholly electro-positive, imparting the
highest value to it for the arts, in all uses of zinc, purely scientific or medicinal, or
for colours for photography, zincography, for rolling, drawing, and spinning, for the
battery for the electric light, for coating iron, especially telegraph wire, for artistic
or any castings, for alloys with other metals, such as copper and nickel, and especially
the brass of which metallic cartridges are stamped, for fittings to shot and shell, and
for cast brass for naval and ordnance purposes, etc.
In the operation, after tapping and while the retort is still pretty full of metal,
charge again with about the same quantity of raw material as that withdrawn
by the tapping of the receiver. Repeat the former manipulation of the extension
pipe; only now the period of closing the receiver, dictated by the appearance of the
zinc, will naturally be shorter.
This process may go on indefinitely in treating material having only traces
comparatively of other metals beside zinc.
In the case of material having much iron, copper, tin or lead, not removed before
filling into the retort, and that of material containing precious metals, the process is
varied.
If the charge be of zinc-silver-lead-alloy, the result of Parkes' process for
disilverizing lead, when the retort is half full, or less, and zinc has ceased to distil
over the receiver is emptied, the heat is now increased so as to remove the last
traces of zinc. When this is firnished the front plate of the retort is tapped below
the charging lip, and the resulting lead-silver alloy cast into pigs for cupelling;
while the zinc oxide and dust are removed from the retort and condenser, and
accumulated for a final reduction with fine coal in the same retort, the resultant
zine from which operation, possibly containing gold and silver, must be used again
in the zincing process at the silver works, the product of the simple distillation on
the other hand is free of other metals. At the end of an engagement of a retort
for precious metalalloy retort and receiver are washed out with lead, which is also
returned to the silver works. As compared with the process of distilling off the
zinc from this alloy now practiced, my Invention, as bearing thereon, possesses the
following advantages, viz. :--Facility to operate on a large scale in one furnace with
economy of plant, of retorts, of fuel and labour, or to operate only with one retort
continuously, so as to save to the silver smelter all delay, non-liability to bury
particles of gold and silver in the substance of the retorts; a regulated heat, neither
encrusting the retorts with coke and clinkers outside, nor allowing lead and silver
to be carried over; greater durability of retorts, as they can be made of clay instead
of plumbago; regaining the bulk of metallic zinc in a form of highest value (if
wanted for use in the silver-lead-works, so that its purity is not essential, the
condenser pipe can be made long and the waterjacket omitted); no loss of any of
the metal.
When copper, lead, tin, etc., are residue in quantity in a retort they are simply
tapped out in front and cast.
When iron alone is expected to be the residue, and would form a saw, then,
when from its accumulation it is necessary to run the retort empty, the heat is
increased to a real white heat, next carbon and fluxes are introduced to melt the
iron in loco, which done it is promptly tapped out. But where iron, tin, lead, etc.,
retain zinc in a combination difficult to deal with except by distillation, as far as
that will go, then upon zinc ceasing to flow the extension pipe is pushed into the
condenser and the heat increased to a point which may carry over lead, etc. The

page_text: condensed product, all in the pipe, is not cast but returned to the kettling furnace.
The residue in the retort is scraped out rather than dealt with by fusion."
The apparatus above described possesses incidental advantages extremely useful
in practice; it is automatic in so far as success with it does not depend on the
intelligence or skill of the workmen. They can hardly fill the retort too full; if
they fired up too much, or the condenser were to become obstructed, the pressure
would spurt molten zinc out of the charging lip. If a retort broke small safety
holes leading into the cold air flues will save the contents. If it were neglected to
work the extension pipe it would ordinarily, even when stationary, perform its
function of catching arsenic, etc., while the physical condition of the interior space
of the receiver being approximately a vacuum is unfavourable for alloying finely
divided particles of metal dust crystals, in which form impurities condense, even of
the metallic zinc duct formed in the beginning of operations, so that such particles
could perhaps float on the surface with impunity, or, more strictly speaking, be
lodged on the thin oxide skin which is generally maintained there, all which,
however, is not stated to invite carelessness.
I may finally state that in case it is desired to use a lined retort in the ordinary
Belgian, Silesian, English, or Stygian zinc ore furnaces the process of carbonizing
may take place in the usual temper oven, or while in the furnace, the precaution
of using pressure with the hydro carbon gas being observed; the safety outlet being
in the front, which is temporarily closed up, such retorts should not remain open
for any length of time. The carbonizing will be found to result in a great saving
of zinc and in retorts, and can usefully be practised also on the condensers if made
of good clay.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said George Barker in the Great Seal Patent Office on the. 11th April
1881.
GEORGE BARKER, of 77, Colmore Row, Birmingham, in the County of Warwick,
Consulting Engineer and Patent Agent. "IMPROVEMENTS IN THE SEPARATION OF
OTHER METALS, AND CHEMICAL COMBINATIONS AND APPARATUS
APPLICABLE THERETO THERETO." A communication from abroad by Albert
Harnickell, of New York, United States of America.
ZINK FROM
My Invention consists of the following processes, whereby I produce cheaply, on
a commercial scale, the chemically pure and dense zinc heretofore only produced at
high cost in the laboratory, making the same now economically available to the
arts and manufactures.
Taking, as my raw material, the ordinary spelter of commerce or any impure
zinc, I smelt the same by a method which involves new features. This first stage
of my total operation removes the grosser and larger portions of the foreign and
nonzinc elements in the commercial or unmerchantable zinc, such as iron, silver, lead,
arsenic, antimony etc.
Thus measurably purified zinc I then subject to an entirely new process of
distributive or selective distillation, aided by the novel apparatus presently to be
described, whereby I eliminate all the residue of nonzinc elements in this part of
my process, making the novel use of the physical fact that the various impurities
which can be volatilized at furnace heat condense at a lower temperature than the
zinc itself, of winning the zinc separately, and the other elements separately, all
without access of air.
In the last place I employ, as a finale of measures taken during the former
process to promote molecular compactness as well as purity, a casting process for
the purified zinc, by which I produce it in the densest possible condition.
And the consequence of this chain of processes in the production of pure zinc, in
the chemically and physically appropriate condition of a much higher specific
gravity and tensile strength that that of any zinc hitherto produced in any except
purely scientific laboratory experiments, whereby this product is rendered of great
value to the arts in the commercial sense.
I proceed to describe first the process which I employ and recommend for
smelting the impure zine, and I would here draw attention to the fact that this
process stands at the outset, and as the first link in the chain of the total process,
whereas, heretofore, in zinc metallurgy, the refining portion of the work, which,
for convenience, I call the smelting (or the kettling) process, has been performed
after and not before distillation.
I take then ordinary or impure zinc or zinc dross and simply melt it to dull red
beat in the reverberatory zinc furnace, or in a muffle, or in a kettle to settle, and
remove lead in the usual way; if present in quantity it cannot all be removed in
this way. After removal of such lead, I plunge to the bottom of the bath sulphur
in an iron pipe or vessel perforated with several holes, each supplied with a wooden
plug held down by a handle, and moved about in the bath always below the
surface; the device of the wooden plugs insures for all but extremely plumbic or
ferric zinc a sufficient prolongation of the infusion of sulphur.
Other reagents may be similarly introduced to meet the case of unusual mixtures
not often appearing in commerce. The effect of the introduction of brimstone in the
presence of iron, even at the moderate beat employed, is the formation of sulphurets,
also arsenites, combined of metallic elements presents excepting the zinc which is
not touched by the sulphur. These sulphurets mixed with some zinc are removed
with the perforated ladles for accumulation, and subsequent repetition of similar

page_text: treatment to liquate zinc out of them. The bath consists now of approximately
pure zinc in an electric state unsuitable for the arts, since it contains much electro
negative zinc, a kind of allotropic condition comparatively useless for the arts, but one
which invariably attends the kettling or other rough processes of separating zinc from
impurities; and I point this out because by my further processes in the campaign I
reverse this molecular condition and render all the zinc electro positive, a fact of
moment in a scientific as well as in a commercial point of view.
This part of my total process gives me the material for the further processes of
distillation and casting, but not absolutely, since material not treated in this first
part, may be at once subjected to the distilling process, as for instance, silver, zinc,
leadscum, or other material with which fluxing or kettling would not be economical
practice.
I describe secondly the new and improved apparatus I have invented and devised,
and which I employ preferentially in the further processes (viz., distilling and
casting) of this new operation of entirely separating zinc on the large scale.
In the accompanying Drawings I show the retort furnace; the retort and its
setting and preparation for distilling; the condensing apparatus; and the casting
mould.
Figure 1 is horizontal sectional view of such furnace, and Figure 2 a vertical
sectional view. The left half of Figure 1 is a section on line 1, 2, the right half one
on line 3, 4, of Figure 2, which latter is a section on line 5, 6, Figure 1; Figure 3
is a vertical longitudinal sectional view of one of the retort chambers.
Figure 4 is a similar view, showing the means for heating the retorts simulta-
neously from without and within.
Figure 5 and 6 are end elevations of the retort furnaces or chambers.
In the Drawings, G is the firebox, which is supplied with air from the ash pit in
the usual way, and from which lead the fire channels J, J, over bridge walls H, H.
The fire passes through combustion chambers K, K, located in the retort furnaces,
from which chambers it passes through openings d, d, over the retorts P, P, and
thence through several openings on the opposite side of the retorts into passages L, L,
which communicate by means of smoke flues M, M, with the chimney Z; Q, Q, are
suitable dampers covering the ends of the channels L, L. Each retort chamber N
is divided longitudinally by a hollow pillar wall X, upon which rests the retort P.
The openings o, 0, 0, 0, can be connected and lead through openings O, O, into the
fire box above and below the grate. By these means a hot blast, as it were,
necessary, may be supplied to the firebox or let into the retort furnaces through
valves R worked by dampers V, Fig. 4, the air being heated in its passages
through the channels o, o, o, o. This hot blast may be used or not as desired, but
these channels or hollow walls are designed in any event to cool the masonry by
allowing air to circulate through them.
if
So much I premise as to the novel furnace, one of the obvious advantages of
which is that in a retort system one or more retorts may be operated separately
from the others, the fire being shut off from all not operated.
I next proceed to describe the retort I employ, which in respect to the material
of which its interior is made, and the manner of finishing it for use is entirely
novel, ensuring a physical action, essential at least to the economy, and, as I hold,
largely contributing to the novel electro-chemical success of my process, and which
features of this retort I count one of the principal parts of my claimed improve-
ments, and as of great value for metallurgical purposes beyond that of this process,
as well in distilling as in melting, including the reduction of zinc from its ores.
The retort is provided with a charging lip A at the one end, Figure 3, and at
the other end with a condensing pipe, necessary to be inclined, R, which leads to
the receiver B. This receiver is preferably set on or into the masonry over the
smoke flue M.
Now viewing the retort and condenser as parts of one apparatus I would say that 5
the retort P is made of good fireclay. The charging lip A may be of any desired
shape. The condensing channel-chamber R, at the other end, must be slightly

page_text: inclined, as shown in Figure 3, and may have branches to be referred to below;
it enters the receiver B.
While I do not claim any particular shape for the body of the retort yet the
general proportions are material. I prefer for wholesale work a retort six feet long
by one foot interior diameter with condenser (and branches if any), and receiver of
proportionate size, as indicated by the figuration; the length of the condensor R
however may be varied under circumstances to be referred to below.
As to the retort proper, apart from the condenser, Figure 3 shows how it is set
upon the pillar wall X; if it is desired to let part of the fire play under its bottom
as well as over it a few saddles may be placed under it; the openings d, d, those
opposite, and the spaces between the saddles must be so calculated as to location
and size as to equalize a distribution of fire or heat around every part of the retort,
counteracting the law that fire seeks the shortest way to the chimney by taking
into account volume, the same as if dealing with water under pressure.
Figure 4 shows the device employed for tempering the clay portion of a new
retort before use. Pipes or flues C, C, are made to lead respectively into the retort
from the fire flue J, and from that into the smoke flue M. By these means the
clay portion of the retort is heated simultaneously from without and within, greatly
lessening the danger of cracking it.
Having thus tempered the clay retorts, or if made of other material than clay,
at all events heated in situ, I next proceed to a special and novel manipulation as
applied to a melting or distilling retort in metallurgy, whereby I close all pores
and fire cracks of the interior and render the inner surface perfectly refractory or
proof against fused or gaseous metal within the retort, so that no part of such metal
can enter the substance of the so specially prepared retort. Thus I prevent all
leakage and waste, and ensure the completest pressure of the gaseous metals; and
a gaseous condition therefore of the zinc itself, as I hold, highly favourable in
connection with subsequent condensation and solidification to high specific
gravity.
In the manipulation special of the interior surface of the retort avail myself of
the experience acquired in making illuminating gas. In that process when a retort
is worked too long or unskillfully it is "carbonized." In that process the
desideratum is to avoid as much as possible carbon deposit in the retort. I, on the
contrary, desire and aim at a deposit, not of carbon indifferently, but of graphite,
not only on the bottom but on the whole interior surface of the retort; and I, in
fact, obtain by decomposition of hydro carbonacious material a specific carbon lining
deposit, which in its physical properties appears to be in the nature of graphite,
giving me thus a retort which partakes of metallurgic advantages of the graphite
or plumbago crucible, only that mine is better, being soiid graphite instead of a
mixture of it with clay, while the outside of my retort offers no carbon to the
oxygen of the fire gases, so that it will last indefinitely, while the plumbago
crucibles of the arts are too soon worn out by exposure to the fire.
To effect this I conduct into the white hot clay retort hydro carbon-gas,
preferentially pure, or else obtained from coal tar, tallow, rosin, or other analogous
substances, and maintain the gas under pressure and subject to decomposing heat
in the retort. Small safety jets 1, 1, lead from the retort for the escape of the
highly hydrogenous surplus products of decomposition of the gas, which are ignited
as shown in Figure 5 and 6. The results of this operation after a certain time, which
will obviously depend upon the force of heat and pressure employed, as well as on
the materials and skill, is that the retort is lined or coated with carbon of peculiar
graphitic character. This interior carbon-layer-lining should be preferably one eight
to one quarter of an inch in thickness, though a less thickness may be sufficient.
After deposit the retort should remain for sometime, not exceeding twenty four
hours, hermetically closed, always under the same heat. In the case of the use of
certain hydro-carbons there would be found if the retort were opened floating
particles of soot, non-graphitic carbon; these can be burned away, but offer no
inconvenience, as they will afterwards find their way into the receiver. The retort

page_text: may now be considered ready for use by attachment of the condenser to it, or of
the receiver to the condenser if the latter was luted in before heating the retort.
Next, as to the specialities of the construction and apparatus of the condenser and
receiver. The condenser, a channel chamber illustrated by a cylindrical pipe (which
however may have branches), is slightly inclined, as shown in Figure 3, and enters
the receiver B.
This latter is of suitable external shape, as indicated in Figure 3, and provided
with a shelf S extending across the whole width of the receiver. The shelf is
Blightly inclined, as shown in the Figure, and should be placed nearly immediately
under the opening of the condensing channel. This shelf is perforated with an
aperture as close as possible to the side of the receiver under the outlet of the
condenser, which aperture should be girdled by a small projecting fender so as to
receive the eventual zine dropping as hereafter described, and pass them below
without splashing. Tapholes are formed in the receiver near the bottom and also
just above the shelf S for letting out contents when desired. A water jacket a is
applied to the condenser R when the operation of the process has gone so far as to
make it necessary to lower its temperature. I prefer it to a sprinkler on account of
the inconvenience of creating steam.
T is a moveable pipe inserted into the side of the receiver directly opposite the
channel condenser pipe R, with which it accurately registers, so as to be able to make
one continuous pipe channel with the condensing pipe when pushed inwards. Its
construction is shown in detail in Figure 7, where f represents a semicircular
partition balf closing the pipe; e is a movable rod carrying a semicircular scraper fl
on its end, adapted to serve in connection with the partition f to completely close
the pipe T when cleaning it. The end plate of this pipe is provided with a glass
or mica window, through which the phenomena in the condenser and retort may be
observed.
Next, as to the casting mould D, Figure 8 and 9. It is made by preference of
zinc, and provided with a cup I to receive the metal as it is poured, and a wide
neck C leading to the main mould D; on either side of the neck are notches g
serving as bearings for the skimmer j (Figure 10). Pius b, b, on either side of the
mould D support it in the water or other refrigerating bath U. The skimmer is
provided with lugs j, j', that rest between the notches g, the skimmer j resting in
the neck C, and serving to skim the metal as it flows under it and retain any dross
or oxide. The water or other refrigerative bath vessel should be of strong con-
struction so as to avoid shaking of the metal in casting by ebullition, and the mould
should be firmly fastened to the vessel.
It is obvious that this mould in toto may not always suit the purposes of casting,
this depending on the kind of work or shapes to be accomplished, but for the purposes
of the general result of my total process, refrigeration without causing coldsets is
too desirable to allow of neglecting the precautions taught by this mould.
Having thus substantially described the apparatus, in so far as it is novel and
improved, which I use in the process of distillative separation of zinc from
impurities, and having above already fully recounted the initial preparation,
when practical, of the raw material, I now proceed to describe, thirdly, the distilling
process, which, combined with the mode of condensation, is a most distinctive part
of my improvements.
I have now to charge the retort with metals, if fluid through the front charging
lip, otherwise through a hopper; at this time and at all times care must be taken
to admit no air into the retort. As regards the composition of the charge, if the
metal has passed through the kettling or first process the impurities still in it are
in the desired physical condition; if not, a little kettling metal ought to be added,
since traces of iron and sulphur are useful in the retort. However, as not every
kind of alloy or mixture can be foreseen, there is no objection to a trifling admixture
of fluxes or reagents, determined by general principles of chemical metallurgy,
and according to the nature of the charge. The heat of the retort is sufficient to
fuse any alloy and probably all mechanical mixtures of zinc, and produce a fluid

page_text: evel inside; accordingly the operation of charging is repeated after intervals, but
so as not more then half fill the retort, nor so quickly as to cool the inside much.
The heat in the chamber is kept at the distilling point of zinc; in the retort it is
of course lower during the act of filling in.
When the operation of charging the retort begins, the long pipe T is pushed
through the receiver B to join the condensing pipe channel R, thus closing the
receiver and leaving as the only outlet from the retort the pipe T. This latter may
be kept shut or set to open by a simple outlet valve to allow of the escape of non-
metallic gases if such are expected; but air must be kept out of it, therefore the
valve should close automatically.
The result of the operation thus far is the volatilization successively according to
their points of distilling temperature of all metals in the retort volatile below the
distilling point of zinc, such as cadmium, antimony, mercury, sulphur, and combina-
tions; fixed ones remain in the retort. These pass through the condensing channel
chamber and condense in the pipe T, which is cool, and are scraped towards its
rear and opening by using the scraper f¹, as explained above. The receiver is thus
kept closed until sufficient condensation of zinc itself in the pipe R gives evidence
of the operation so far as other fugitive metals are concerned being complete.
These other metals can be saved separately if desired, such as cadmium, etoa.,
by keeping the pipe well cleaned of substances condensing successively prior to zinc
where poisons like arsenic, antimony, or mercury are expected to appear in sensible
quantity their special metallurgy must dictate precautions. Where amalgum of zinc
and mercury is treated, condenser and receiver had better be of wrought iron, and
pipe T end in a vessel of water, the heat to be below the distilling point of zinc,
which will however distill over with the mercury in small quantity, and lodge in
the receiver, in which the heat will be sufficient to continue driving mercury into
the cool pipe T. The zinc gained and that remaining in the retort is not pure and
should be considered as raw material.
One salient point of difference between my process and that of ordinary zinc
winning is apparent. I have comparatively an immense quantity of zinc in the
retort and obtain an immense pressure, which I purposely maintain by not having
a large outlet orifice.
Recurring to the normal process, when solid or liquid zinc appears in quantity
in the extension pipe T, the next thing to be done is to draw out the pipe T so as
to disconnect it from the condensing channel chamber; it should be drawn through,
so as to leave its end flush with the inner side of the receiver B.
Now at this stage the zinc in the retort distils over, condensing in the pipe or
channel chamber R, which is heated by the great latent heat set free by the zinc
in passing from a gaseous to a liquid state, at first sufficiently, and afterwards more
than sufficiently to prevent solidification. The metal runs out of the condenser R,
and through the orifice in the shelves S, to the warmed bottom of the receiver B,
where it accumulates.
At this point it is necessary to make mention of a supplementary construction
to the condensing channel chamber, sometimes called pipe R, which was above
referred to as its "branches." The phenomena regarding heat occuring between
the retort and the receiver are, that the condenser R is subject to beat from three
sources, vis., 1, the clay of the retort; 2, the heat of the interior of the retort
from which it leads; 3, the latent heat of the zinc condensing around the inner
periphery. The intensity of the first two sources decreases with the distance of
any point in the condenser R from the retort, the intensity of the third source is
uniform. In ordinary zinc condensing only radiation is availed of to get rid of
the heat, while I cool the outside of the condenser artificially; the immediate effect
of such cooling is upon the inner periphery, hence it is a factor bearing upon the
latent heat, leaving the two first sources of heat in the condenser as main factors
in the nice calculation for the object aimed at, viz., the maintainance of sufficient
heat in the condenser to keep fugitive impurities volatile, but not enough to keep
zinc in a gaseous state. In a long pipe zinc and impurities would at a certain

page_text: point condense or mix together. Hence I limit the length, or rather the distance
of the extremity of the condenser from the retort. But while for a moderate task
the single pipe R may be sufficient, if it is desired to distil great quantities at
great speed, instead of relying on the superficial idea that then greater retort hent
would authorize greater length of condensing pipe, it is much safer to avoid
lengthening distance from the retort orifice and to increase the cooling surface of
the condenser, by letting T branches bulge out from it radiating upwards, so that
the zinc condensed therein shall flow into the main stem.
It will be found that any irregular product, zincdust, oxide, and impurities
will lodge on the cool shelf S and above it, or go over into the cooler extension
pipe T which is open to the receiver. When the outside of the condensing
channel R grows red hot, only zinc goes over.
At this time the waterjackets (a) must be applied around R (and branches, if
any), to reduce its temperature and enable it to condense all ascending gaseous
zines in such wise, that it shall not be condensed in the receiver or the extension
pipe T, nor run in a red hot state into the lower receptacle.
At regular
intervals, and before charging again, the receiver must be tapped. The lower
taphole is opened and the lower part of the receiver emptied. The resultant zinc is
chemically pure.
This must be allowed to cool without chilling until the skin with adhering clay
or dirt can be taken off with one skim. All contact with iron or other metals
should be avoided, even iron tools should not be used. The final operation is to
cast. This is done in the water mould D above described. This is previously
cleaned and polished, and for castings for rolling zinc is set slightly out of level so
as as yield the usual form of plate with one surface inclined.
While this artificial cooling is prescribed for ingot and plate casting with artistic
or hollow castings, the same principle is applied from the fact that the moulds are
thick and cool, and with my zinc, which is fluid as water, yield extremely thin
hollow castings very perfectly and of much greater tensile strength than with any
other zinc. But the moulds must be kept cool to maintain perfect result.
By way of explanation I would say, this arrangement of the novel apparatus and
the manipulations give me chemically pure zinc, as is easily comprehended.
Were it not thus pure no pains to make it into a piece of metal of entirely
electropositive character as a whole, or of comparatively great density, would be of
any avail.
But because mine is, it is worth wile to do for it all that can be done to insure
my obtaining it in the condition of greatest density or specific gravity.
I hold that the density of zinc may be greater or lesser while in the gaseous and
in the molten, as well as while it is in the solid and in the wrought state, and that
under the precautions I have devised, the density gained in one state is not wholly
lost (as is popularly assumed) when it passes into the other state, so that with my
zinc the artizan or scientist shall, on a first use of it, be able to derive the benefit of
this novel quality of greater specific gravity than that of other (even pure) sorts
of zinc.
This then is the object of the apparently curious process rules laid down, which
are the reverse of those for zinc making as hitherto practiced, viz., to maintain
rather than relieve great pressure in the retort; to increase it at the point of
condensation by having a narrow short outlet from the retort, presenting never-
theless sufficient condensing surface because artificially cooled, instead of an ample
outlet and spacious condenser as at present; to remove the molten zinc thus 5
gained at once from the influence of further heat, instead of leaving it exposed to
it or allowing it to solidify so as to require a remelting, both of which are the
present practices; to cool the zinc, if necessary, down to a simply free flowing state
before casting, instead of being indifferent to it as at present; to chill it (without
bringing it in contact with water) at the moment of crystallization, instead of 5
cooling is afterwards or keeping it warm for use, both of which are present
fashions.

page_text: Made and cast in the way above indicated, the product is of high specific gravity
equal to that of the rolled zinc of commerce, and wholly electro-positive, imparting
the highest value to it for the arts, in all uses of zinc, purely scientific or medicinal,
or for colours for photography, zincography, for rolling, drawing, and spinning, for the
battery for the electric light, for coating iron especially telegraph wire, for artistic
or any casting, for alloys with other metals, such as copper and nickel, and
especially the brass of which metallic cartridges are stamped, for fittings to shot
and shell, and for cast brass for naval and ordnance purposes, &ca.
In the operation, after tapping, and while the retort is still pretty full of metal,
charge again with about the same quantity of raw material as that withdrawn by
the tapping of the receiver. Repeat the former manipulations of the extension
pipe T, only now the period of closing the receiver, dictated by the appearance of
the zinc, will naturally be shorter.
This process may go on indefinitely in treating material having only traces
comparatively of other metals beside zinc.
In the case of material having much iron, copper, tin, or lead not removed
before filling into the retort, and that of material containing metals, the process is
varied.
If the charge be of zinc-silver-lead alloy, the result of Parke's process for
disilverizing lead, when the retort is half full, or less, and zinc has ceased to distil
over, the receiver is emptied; the heat is now increased so as to remove the last
traces of zinc. When this finished the front plate of the retort is tapped below
the charging lip, and the resulting lead-silver alloy cast into pigs for cupelling,
while the zinc oxide and dust are removed from the retort and condenser and
accumulated for a final reduction with fine coal in the same retort, the resultant
zinc from which operation, possibly containing gold and silver, must be used again
in the zincing process at the silver works; the product of the simple distillation on
the other hand is free of other metals. At the end of an engagement of a retort for
precious metalalloy retort and receiver are washed and with lead, which is also
returned to the silver works. As compared with the processes of distilling off the zinc
from this alloy now practiced, my Invention as bearing thereon possesses the following
advantages, viz. :-Facility to operate on a large scale in one furnace with economy
of plant, of retorts, of fuel, and labour, or to operate only with one retort con-
tinuously, so as to save to the silver smelter all delay; non-liability to bury particles
of gold and silver in the substance of the retorts; a regulated heat, neither
incrusting the retorts with coke and clinkers outside, nor allowing lead and silver
to be carried over; greater durability of retorts, as they can be made of clay
instead of plumbago; regaining the bulk of metallic zinc in a form of highest
value (if wanted for use in the silver-lead-works, so that its purity is not essential,
the pipe R can be made long and the waterjacket omitted); no loss of any of the
metal.
When copper, lead, tin, et cetera, are residue in quantity in a retort, they are
simply tapped out in front and cast.
When iron alone is expected to be the residue and would form a sow, then when
from its accumulation it is necessary to run the retort empty, the heat is increased
to a real white heat, next carbon and fluxes are introduced to melt the iron in loco,
which done, it is promptly tapped out. But where iron, tin, lead, et cetera, retain zinc
in a combination difficult to deal with except by distillation, as far as that will go,
then upon zinc ceasing to flow the extension pipe is pushed into the condenser,
and the heat increased to a point which may carry over lead, et cetera. The condensed
product all in the pipe is not cast but returned to the kettling furnace. The residue
in the retort is scraped out rather than dealt with by fusion.
The apparatus above described possesses incidental advantages extremely useful
in practice; it is automatic in so far as success with it does not depend on the
intelligence or skill of the workmen. They can hardly fill a retort too full; if they
fired up too much, or the condenser were to become obstructed, the pressure would
spurt molten zinc out of the charging lip. If a retort broke small safety holes

page_text: leading into the cold air flues will save the contents. If it were neglected to work
the extension pipe it would ordinarily, even when stationary, perform its function
of catching arsenic, et cetera, while the physical condition of the interior space of the
receiver, being approximately a vacuum, is unfavourable for alloying finely divided
particles of metal dust crystals, in which form impurities condense, even of the
metallic zinc dust formed in the beginning of operations, so that such particles
could perhaps float on the surface with impunity, or more strictly speaking, be
lodged on the thin oxide skin which is generally maintained there. All which,
however, is not stated to invite carelessness.
I may finally state that, in case it is desired to use a lined retort in the ordinary
Belgian, Silesian, English, or Styrian zinc ore furnaces, the process of carbonizing
may take place in the usual temper oven, or while in the furnace, the precaution of
using pressure with hydro carbon gas being observed, the safety outlet being in
the front, which is temporarily closed up. Such retorts should not remain open for
any lenth of time. The carbonizing will be found to result in a great saving of
zinc and in retorts, and can usefully be practiced also on the condensers if made of
good clay.
Having thus fully described the said Invention, as communicated to me by my
foreign correspondent, and the manner of performing the same, I would have it
understood that I claim,-
In a refining process of impure zinc, the introduction at the bottom of the zino
bath of brimstone, in the presence of iron, through a tool from which it can fuse
out only slowly, for the purpose set forth.
In the distilling process of zinc, whether during reduction in the ore-furnace,
or when dealing with zinc other than ore in such ore furnace, or in a special
furnace,―
a. The use of a perfectly impenetrable retort or muffle, having a small outlet and
a narrow short condenser for zinc of ample surface, nevertheless permitting of
artificial cooling on the outside; also this same condenser, with any zinc retort, for
the purpose of obtaining under great pressure rapid condensation of all the zinc in
liquid form without formation of zinc dust.
b. In combination with what is claimed under a, or for any zinc condenser, a
receiver into which the condenser automatically discharges, for the purpose of
relieving it of the heat of the accumulated metal, thereby increasing its condensing
power, and in which receiver the zinc shall remain simply liquid and protected
against oxydation.
c. In combination with what is claimed under a, and also under b, or under either,
one or more extensions to the zinc condenser not accessible to the fluid condensed
zinc, for the purpose of therein condensing or lodging impurities requiring a lesser
heat than zinc for condensation.
d. The device of keeping the condenser, receiver, if any, and the separating
extension part connected with both hermetically closed to the entrance of air, for
the purposes of preventing oxydation and of promoting distillation as being thus
done in vacuo.
e. In combination with either the condenser, the receiver, or the extension part
thereof, the use of an outlet valve for the purpose of an automatic discharge of non
metallic gases without admitting air, the same being placed at a distance from the
heat so as to work freely.
In any distilling process of zinc the manipulation of removing the impurities
which distil at lower heat than zinc, by catching them during such heat of the
retort in a moveable extension tube pushed up, or into, or through the condenser for
zinc proper, all without admitting air.
In any wholesale distilling process of zinc the application of artificial refrigeration
of the condenser at will, both for the purpose of increasing its condensing faculty
and of calming the fierce fusion of the obtained metal.
In any process for the production of very pure or chemically pure zinc, all the
foregoing claims singly and in combination.

page_text: In any process of wholesale casting of pure zinc, the employment of artificial
refrigeration of the casting mould, which mould shall be fed amply with metal, for
the purpose of producing a dense casting without cold setts.
A new working process in the metallurgic treatment of zinc, for the purpose of
obtaining this metal chemically pure and of greater specific gravity than hitherto
by means of distillation under great pressure, separate condensation in vacuo, and
non contact of impurities with the zinc, and, if requisite, chilling of the same at
casting, with the use of the apparatus I have invented and herein also claim, or
with any other apparatus by which these manipulations may be executed, all which
process I have more particularly set forth for instruction in the forgoing
Specification.
In a retort furnace, a fire flue and a smoke flue located at the opposite ends of a
retort, and communicating with each other through the medium of channels
parallel to the sides of the retort, and provided with a double series of openings
communicating with the said channels for conducting the flames around the retorts,
as set forth, in combination with the firebox and stack, the flues J, K, L, M, the
retorts P, and furnaces N, as set forth.
In combination with the common firebox G, the retort furnace wings located at
either side of the same, and provided with channels J, K, L, and ducts M, leading
to the common stack E, the channels L being provided with dampers Q, as set
forth. The retort furnaces N, having openings 0, 0, communicating with the
firebox below or above the grate, or both, as described.
In combination with the retort P and pipe R, the receiver B, having perforated
false bottom S, as set forth.
The receiver B, having registering condensing pipes R, T, as set forth.
In combination with the retort P, the receiver B having the inclined registering
pipes R, T, adapted to admit of the discharge of condensed products and of the
inspection of the colour in the retort, as described.
In combination with the receiver B the pipe T, having semicircular partition f
and scraper f¹, substantially as described.
In combination with the retort furnace N and flues J, K, L, M, the pipes C
connecting the flues M, J, with the interior of the retorts, as described.
The water mould D having the automatic comb j, as set forth.
In combination with the mould D having neck c, the pivoted comb j, substantially
as set forth.
A mould for casting spelter made preferentially of zinc, and provided with a
water bath for making dense castings, as described.
The method herein described of preparing metallurgical retorts, consisting in
coating them internally with a deposit of graphitic carbon formed by a decom-
position with the retort of a hydro carbon gas, as and for the purposes set forth.
This method of coating the retort internally with graphitic carbon, consisting in
subjecting a hydro carbon with the retort to heat and pressure, as set forth,
In witness whereof, I, the said George Barker, have hereunto set my hand
and seal, this Ninth day of April, in the year of our Lord One thousand
eight hundred and eighty one.
ARADAT