CERTAIN IMPROVEMENTS IN THE TREATMENT OF SLAGS. ORES. AND COMPOUNDS OF TIN.'
Year: 1866

page_text: LETTERS PATENT to Joseph Jean Marcais, of Paris, in the Empire of
France, Engineer, for the Invention of "CERTAIN IMPROVEMENTS IN THE
TREATMENT OF SLAGS. ORES. AND COMPOUNDS OF TIN.'
PROVISIONAL SPECIFICATION left by the said Joseph Jean Marcais at
the Office of the Commissioners of Patents, with his Petition, on the
22nd May 1866.
I. JOSEPH JEAN MARCAIS, of Paris, in the Empire of France, Engineer,
do hereby declare the nature of the said Invention for CERTAIN IMPROVE-
MENTS IN THE TREATMENT OF SLAGS, ORES, AND COMPOUNDS OF TIN," to be as
follows:-
The main objects of my Invention are to extract from scorice all the
tin which they contain, to purify the tin and separate it from metals,
metalloids, and from other bodies with which it may be united, alloyed, or
combined, to obtain directly from the scori.r, sum, alloys, and impure tin
saleable chlorides of tin and different salts of tin, and to extract from ores,
alloys, and combinations of tin the precious metals that may be found
therein.

page_text: By my Invention the numerous washings to which tin ore is usually
subjected to bring it to the requisite richness for smelting are rendered
unnecessary, and I avoid the loss sustained by the ore in smelting by the
formation of the scoria which carry away a considerable quantity of tin.
The ores containing wolfram, and those which contain none, may be treated
with the same advantage, and ores containing wolfram have a certain eventual
superiority, and the tungsten of these ores is given to commerce without
much additional expense.
or
My Invention, therefore, mainly relates to a mode of extracting
separating tin. from the matters with which it may be united, combined, or
alloyed in scoriæ, dross, or scum ores, or various compounds of tin, by sub-
jecting such scoriæ, dross, or scum ores, compounds or stanniferous matters
under a high temperature to the action of hydrochloric acid gas.
I proceed to describe certain means of carrying this method into effect,
without restricting myself to the details.
The fire is managed so
The scorice when produced from ores in the usual manner are thus treated
according to my Invention:-I first pulverize and sift the scoriæ, and I then
add a little coal, coke, or charcoal, also previously sifted; this powder I
make into lumps, starch, glue, treacle, pitch, tar, or other similar substances
may be used as a binding agent. The lumps are dried and subjected to and
maintained at a temperature bordering on the point of fusion, but beneath it,
the volatile matter evaporates, and the lumps are left spongy and permeable;
the lumps are heaped one on the other in a retort heated and arranged like
gas retorts; when charged the retorts are luted.
as to get up the heat in the retort, and maintain it at the degree just below
that at which the lumps would begin to melt. When this temperature is
attained and not exceeded, a current of heated hydrochloric gas (II. CL.) is
caused to pass through the mass of lumps. The gaseous current carries with
it the thick vapours which deposit in a vessel, the communicating pipes between
the retort and receiver should be preferably nearly of the same section as the
retort to avoid stoppage. Besides the vessel which receives the vapour a
series of other vessels fitted with tubes is used to collect the vapours that are
not condensed in the first vessel, and to collect the more volatile of the gaseous
products; there are also jars for transforming into liquid hydrochloric gas
in the ordinary way the gaseous or aeriform hydrochloric gas which has not
been exhausted in its passage over the scoria. The gaseous products that
have not been absorbed circulate in long damp flues, whence they escape into
the atmosphere. By the action of hydrochloric gas at a high temperature
the metalloids and metals are attacked and for the most part carried over. Tin,

page_text: iron, manganese in the form of chloride, antimony in the form of chloride,
and of antimoniated hydrogen, sulphur in the form of chloride and of
sulphuretted hydrogen, arsenic in the form of arseniated hydrogen, and in
other forms. Some metals in the chlorides are less easily separated, and
may remain entirely or in part in the retort. These chlorides are also liable to
be carried over; there always remains in the retort a certain quantity of chlorides
which are retained in the body of the lumps. The wolfram of scoriæ containing
wolfram is attacked, and the iron and the manganese volatilise in the form of
chloride; the tungsten remains in the scoriæ; sometimes a small portion of
tungsten volatilises in the form of chloride.
The separation of the products should take place, 1st, with respect to the
bodies carried over in form of vapours, and deposited in the receivers; 2nd,
and the bodies left in the retorts. Most of the substances carried over are
found in the first receiver, they are taken up again by the water acidified
by the hydrochloric acid, the addition of acid preventing the formation of
oxichlorides; a portion of these substances dissolves in the acid liquor, and
a portion remains insoluble. The whole is subjected to ebullition during some
minutes to rid it of the free sulphuretted hydrogen, and it is afterwards
filtered, there remains on the filter chiefly sulphur of tin and of antimony,
often arsenic and sulphur, occasionally a small portion of silver, gold, and
oxide of tin, this oxide arising from the action on the chloride of the steam
of water passing over with the hydrochloric gas, and in the case of the scoric
of wolfram sometimes acid of tungsten. The sulphurs spoken of are pro-
duced either directly or by the presence and passing over of sulphuretted
hydrogen amongst the chlorides. The tungstic acid is the result of the
decomposition of the chloride of tungsten affected by the acidified water.
All bodies remaining on the filter are put away after each operation, and
treated afterwards in sufficiently large quantities; they are then roasted with
care, and afterwards reduced and melted. If the tin remaining on the filter
only contain traces of manganese and of iron, little or no antimony, and no
sulphur, and if it be not mixed with either tungsten or any other body, it will
yield tin after fusion; but frequently the result of melting will be an impure
metal which must be treated like I treat scum as herein-after described.
The filtered liquor contains chlorides, of antimony, tin, iron, and manganese.
The chloride of antimony is precipitated in the form of metal by immersing a
tin plate in the liquor which precipitates the antimony, and retains it in the
form of proto-oxide of tin and iron. The chloride of tin crystallizes amidst
the chloride of iron and manganese, and may be obtained by washing the
crystals with a saturated solution of pure chloride of tin; this frees it from

page_text: every trace of iron, manganese, or other chloride.
Chloride of iron and of
manganese remain in the mother waters, and increase in quantity as the
tin crystallizes. The crystallization should be effected without exposure to
the air; there is a point at which the mother waters will no longer yield
pure chloride of tin; the remaining tin may be separated by introducing a
tin plate and organic substances, and the mother waters treated by carbonate
of lime, which precipitates the tin and leaves the iron and other metals in
solution. The oxide of tin is calcined, and thus rendered less liable to be
attacked; it is freed of excess of lime and metals carried over, and iron and
manganese by washings with hydrochloric acid mixed with water, and finally
melted in a reducing oven. The chlorides of iron and manganese, as well as
the alkaline and earthy chlorides which may exist in the liquor, are evaporated.
till dry at a moderate temperature to avoid volatilzation. They serve to
produce hydrochloric acid. The antimony produced by precipitation by the
tin plate is melted and utilized, arsenic, produced by roasting as well as from
the decomposition of arseniated hydrogen in the flues communicating with the
chimney can also be used as well as that portion of antimony which goes over
in the form of antimoniated hydrogen. The residual chloride of tin and
chloride of iron remaining in the body of the lumps in the form of inter-
positions may be gathered by washing with acidulated water; the wash
water is added to the preceding solutions. If the scoriæ contain lead
or precious metals they will be found mostly in the retort. In the
case of wolfram the tungsten remaining in the scoriæ can be separated
from the silicate of alumina and from other oxides by the usual means
employed, and thereby obtained in a pure state; this tungsten could be
employed in the metallurgy of iron and in the manufacture of colours.
I treat the scum of tin like the scorire, if brittle it is pulverized, if malleable
it is melted into grains; in either case it is made into lumps, with the addi-
tion of powdered charcoal and coagulated with starch, pitch, or other sub-
stance; these lumps are introduced into the retort like those formed with
scoriæ, and are heated to just below the point of fusion and subjected to a
current of heated hydrochloric gas. My process of treatment, reaction, and
separation of the products are exactly the same as those which are employed
for the scoriæ. Impure tin and residues of working alloys may also be
treated by my processes and operations as described for treating dross. Tin
ore, properly so called, is first brought by washings to the requisite state for
making scoriæ and roasted if they contain too much sulphur; they are then
converted into scoriæ in reducing furnaces, with or without fusing agents,
according as the gangue may or may not yield fusible glass. Contrary to the

page_text: ordinary principles of metallurgy it is advantageous to obtain scoria which
only melt at a high temperature; these scoriæ are then pulverized and a small
quantity of charcoal added, and they are converted into lumps piled in the
retorts and subjected to a current of hydrochloric acid gas. The products
are treated and separated as aforesaid. Theoretically tin ore might be reduced
by a reducing gas current without raising the temperature sufficiently high to
produce scorification, the molecules of ore reduced to metal separated from
the midst of the gangue would be considered as dross or scum, and should be
attacked by hydrochloric acid, but practically I prefer complete scorification.
In working I usually place chloride of sodium in the retort of the hydrochloric
acid furnace.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said Joseph Jean Marcais in the Great Seal Patent Office on the
22nd November 1866.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, JOSEPH
JEAN MARCAIS, of Paris, in the Empire of France, Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-second day of May, in the year of our
Lord One thousand eight hundred and sixty-six, in the twenty-ninth year
of Her reign, did, for Herself, Her heirs and successors, give and grant
unto me, the said Joseph Jean Marcais, Her special licence that I, the
said Joseph Jean Marcais, my executors, administrators, and assigns, or such
others as I, the said Joseph Jean Marcais, my executors, administrators,
and assigns, should at any time agree with, and no others from time to time
and at all times thereafter during the term therein expressed, should and
lawfully might make, use, exercise, and vend, within the United Kingdom of
Great Britain and Ireland, the Channel Islands, and Isle of Man, an Inven-
tion for "CERTAIN IMPROVEMENTS IN THE TREATMENT OF SLAGS, ORES, AND
COMPOUNDS OF TIN," upon the condition (amongst others) that I, the said
Joseph Jean Marcais, my executors or administrators, by an instrument in
writing under my, or their, or one of their hands and seals, should particularly.
describe and ascertain the nature of the said Invention, and in what manner
the same was to be performed, and cause the same to be filed in the Great
Seal Patent Office within six calendar months next and immediately after the
date of the said Letters Patent.
NOW KNOW YE, that I, the said Joseph Jean Marcais, do hereby

page_text: declare the nature of the said Invention, and in what manner the same is to
be performed, to be particularly described and ascertained in and by the
following statement thereof, that is to say:-
The main objects of my Invention are, to extract from scoriæ slags, ores,
and compounds all the tin which they contain, to purify the tin, and separate
it from other metals and metalloids and other bodies with which it may be
united, alloyed, or combined, to obtain directly from scoriæ scum, alloys, and
impure tin, saleable chlorides of tin, and various salts of tin,-and to extract
from ores alloys and combinations of tin the precious metals that may be found
therein.
By my Invention the numerous washings to which tin ore is usually
subjected to bring it to the requisite richness for smelting are rendered
unnecessary, and I avoid the loss which is sustained by the ore during the
smelting process by the formation of scoriæ which carry away a considerable
quantity of tin. Ores containing wolfram, and those which contain none, may
be treated with the same advantage by means of my Invention, and ores con-
taining wolfram have when so treated a certain eventual superiority; the tung-
sten of these ores is given to commerce without much additional expense.
7 My Invention then relates to a mode of extracting or separating tin from
the matters with which it may be united, combined, or alloyed in scoriæ, dross,
scum ores, or other compounds of tin, and it consists in subjecting such scoriæ,
dross, scum ores, compounds, or stanniferous matters under a high temperature
to the action of hydrochloric acid gas.
I now proceed to describe particularly the best means of carrying this Inven-
tion into effect:-
First, Scorim Produced in the usual Treatment of Ores.-Preparation.-
The scoriæ when produced from ores in the usual manner are thus treated
according to my Invention:-I first pulverize the scoria and then sift
them; I pulverize them so as to render them sufficiently fine to allow of their
passing through a middle-size sieve. I consider a sieve of copper wire of
about 40 or 50 threads or wires to the square inch most suitable for the
purpose. I add to this sifted scoria a little coal, coke, or charcoal, which
is also previously pulverized and sifted through the same sieve as is used for
the pulverized scorice; coal, coke, or charcoal may be employed for the
purpose, but I prefer charcoal. This powder, that is to say, the powdered
and sifted scoriæ, mixed with the powdered and sifted coal, coke, or charcoal,
I make into lumps or blocks after the manner of patent fuel. Starch, glue,
treacle, pitch, tar, or other similar substance is used as a binding agent in
making these lumps or blocks. I make the lumps of the size of an ordinary

page_text: walnut. The lumps are then dried by any ordinary drying apparatus, and
they are then subjected to and maintained at a temperature bordering on the
point of fusion, but beneath it. The volatile matter evaporates, and the lumps
are left spongy and permeable or porous.
Process or Operation. The lumps or blocks having been prepared as above
described are heaped one on another in a fire-clay retort arranged and heated
like ordinary gas retorts. When the retorts are charged they are carefully
luted. The fire is managed so as to get up the heat in the retort and maintain
it at a degree just below that at which the lumps would begin to melt. When
this temperature is attained, but not exceeded, that is to say, when the tem-
perature reaches a point a little below that at which the lumps would begin
to melt or enter in a state of fusion, or, in other words, when the lumps are
at a cherry-red heat, I cause a current of heated hydrochloric acid gas (H. CI)
to pass through the lumps. This gaseous current carries with it the thick
vapours which deposit in a vessel which is provided to receive them, and
which communicates with the retort by a pipe; this pipe is of nearly the same
transverse section as the retort, to avoid obstruction, and it is so arranged
that a rod may be easily introduced for stirring its contents. In addition to
the above vessel which receives the vapours I provide a series of other vessels
fitted with tubes, and intended to receive and collect the vapours which are not
condensed in the first vessel, and they serve at the same time to collect the
more volatile of the gascous products. There are also jars or vessels for
liquefying in the ordinary way the hydrochloric gas which has not been'
exhausted in its passage over the scorice. The gascous products which have
not been absorbed circulate in long and damp flues, wherefrom they escape
through chimneys into the atmosphere.
Results of the Operation.--By the action of the hydrochloric acid operating
on the lumps at a high temperature (that is to say, by preference at a cherry-.
red heat) the metalloids and metals are acted upon, separated, and for the
most part entirely or partially carried over. Tin, iron, manganese in the form
of chloride, antimony, partly in the form of chloride, and partly in the form of
antimoniated hydrogen, sulphur partly in the form of chloride of sulphur,
partly in the form of sulphuretted hydrogen, arsenic partly in the form of
arseniated hydrogen, partly in other forms less easy to define. Some metals
in the chlorides are less easily separated, and may remain entirely or in part
in the retort; such is the case with lead, silver, and gold, and with alkaline
and earthy metals; these chlorides are also liable to be carried over, in fact,
there always remains in the retort a certain quantity of chlorides, even the

page_text: most volatile, which are retained in the body of the lumps themselves, The
wolfram of scorim which contain wolfram is attacked or acted on, and the
iron and the manganese volatilize in the form of chloride. The tungsten
remains in the scoriæ; sometimes a small portion of the tungsten volatilizes
in the form of chloride.
Separation of the Products.-The separation of the products should take
place, first, with respect to the bodies which are carried over in the form of
vapours and deposited in the receivers; secondly, with respect to the bodies
or matters left in the retorts.
Bodies or Matters carried over.-Most of the substances carried over are
found in the first receiver; they are taken up again by the water; acidified
by the hydrochloric acid; the addition of acid acts as a means of preventing
the formation of oxichlorides. A portion of these substances dissolves in the
acid liquor, and a portion remains insoluble. The whole is subjected to
ebullition in order to rid it of the free sulphuretted hydrogen, and it is
afterwards filtered. There remains in the filter chiefly sulphuret of tin and
of antimony, and often also considerable proportions of arsenic in various
forms, and likewise of sulphur, occasionally a small portion of silver, gold,
and oxide of tin; this oxide arises from the action on the chloride of the steam
(of water) passing over with the hydrochloric gas, and in the case of the
scoria of wolfram, sometimes acid of tungsten. The sulphurets spoken of
above are produced either directly or by the presence and passing over of
sulphuretted hydrogen amongst the chlorides. The tungstic acid is the result
of the decomposition of the chloride of tungsten affected by the acidified water.
All bodies remaining on the filter are collected after each operation, and
treated afterwards in sufficiently large quantities, the treatment being very
simple; they are roasted carefully, and afterwards reduced and melted. If
the tin which remains on the filter only contain traces of manganese and iron
little or no antimony, and no sulphur, and if it be not mixed with either tungsten
or other body, it will, after having been melted, yield tin of good saleable
quality; but most frequently the result of the melting will be only an impure
metal, which must be treated in the manner herein-after described for treating
the scum of tin, and subjected to the same process as is herein-after described
for that product. The filtered liquor will contain a profusion of chlorides, but
of these the following only are in most cases of any interest as regards market-
able or manufacturing purposes:-These are chlorides of antimony,
tin, iron, and manganese. The chloride of antimony is precipitated in the
form of metal by immersing a tin plate in the liquor; this lin plate precipitates

page_text: the antimony, and holds it in the form of proto-oxide of tin and iron. The
chloride of tin crystallizes amidst the chloride of iron and manganese, and
may be obtained of good saleable quality by merely washing the crystals with
a saturated solution of pure chloride of tin, which washing frees it from every
trace of iron, manganese, or other chloride which may exist therein.
Chlorides of Iron and of Manganese.-These chlorides remain in the mother
waters, and increase in quantity as the tin crystallizes. The crystallization
should be effected without exposure to the air. There is a point at which the
mother waters will no longer yield pure chloride of tin; thereupon, to separate
the remaining tin, I introduce a tin plate and certain organic substances in
the ordinary manner, and I treat the mother waters by carbonate of lime also
in the ordinary manner, which precipitates the tin, and leaves the iron and
other metals in solution. Besides this method of separation there are a
number of other ordinary methods familiar to chemists which may be employed
for the above purposes successfully. The oxide of tin is calcined, and thus
rendered less liable to be attacked; it is freed of excess of lime and of metals
(which have been carried over) and of iron and manganese by washings with
hydrochloric acid mixed with water, and it is finally melted in a reducing
furnace. The chlorides of iron and manganese, as well as the alkaline and
earthy chlorides which may exist in the liquor are evaporated till dry at a
moderate temperature to avoid volatilization; they may also serve to produce
hydrochloric acid. The antimony produced by precipitation by means of the
tin plate is melted and utilized. Arsenic produced by roasting, as well as that
derived from the decomposition of arseniated hydrogen in the flues which.com-
municate with the chimney, can also be used as well as that portion of anti-
mony which goes over in the form of antimoniated hydrogen.
Bodies left in the Retort.-Generally the residua which have not been
attacked contain nothing useful except a little chloride of tin and a certain
quantity of chloride of iron remaining in the body of the lumps themselves
in the form of interpositions. All these may be collected by washing with
acidulated water; the wash water is added to the preceding solutions.
If the scoriæ contain lead or precious metals (which is very seldom the
case) they will be found mostly in the retort. In the case of wolfram the
tungsten remaining in the scoriæ can be separated from the silica of alumina
and from other oxides by the usual means employed, and thereby obtained in a
pure state. This tungsten could be employed in the metallurgy of iron and
in the manufacture of colors.
Scum or Dross, Impure Tin, Residue of Working Alloys.-Scum or-dross.-
The name of scum or dross is given generally to the blackish matter more or

page_text: less mixed with scorice which floats on the surface of the metallic baths. The
scum of tin is very rich; it is sometimes found to contain as much as 75 per
cent. of metallic tin; it is sometimes malleable, but more frequently brittle;
its composition varies considerably. I treat the scum of tiu exactly like I
treat the scoriæ; if it be brittle it is pulverized, if malleable it is melted
into grains; in either case it is made into lumps, with the addition of powdered
charcoal and coagulated with starch, pitch, or other suitable substance in the
well-known manner. These lumps are introduced into the retort in the same way
as those which are formed with the scoriæ, from which they differ little except
by their richness, and they are heated to just a little below melting point (or say
to a cherry-red heat, just under the point of fusion), and when at that tem-
perature they are subjected to a current of heated hydrochloric gas as described
for the treatment of scoriæ.
The mixing of charcoal with the scoriae and with the scum or dross has
(and especially in the latter case) two advantages:-First, it assists the action
of the hydrochloric acid; and, secondly, it prevents the particles of
scoriae or scum which would melt under too high a temperature from uniting
or coagulating.
My process of treatment and the mode of operation or reaction and separation
of the products are exactly the same as those described as employed by me in
treating the scoriae.
It has been stated that lead, silver, and gold are rarely found in scoria,
properly so called, but in scum or dross; on the contrary, lead and silver are
frequently met with. Almost all the lead remains in the retort in the form of
chloride. The major part of the silver also remains in the retort; it is generally
in a soluble form, probably in the form of multiple chloride. Gold has also
been found.
We do not suggest any particular method of separating the precious metals
because the methods are well known; chemistry already furnishes ample instruc-
tions on that head. It is prudent not to confine the search after silver and
gold to the retort, but to continue it at the same time through all the products
in which these metals may exist, either by combination or by being carried
over, thus in the precipitates of antimony in the deposits remaining on the filter
it would be advisable to test the soluble chlorides.
With regard to lead, the slight tendency of its chlorides to solubility admits
of its being easily separated by crystallization.
As regards the separation from tin of other numerous metals and metalloids
which may be found in various scoriæ or dross reference must be made to various
published treatises on chemistry; indeed, it would be impossible to give all the

page_text: details of these processes without swelling the description to the extent of a
treatise.
Impure Tin and Residua of Working Alloys. All these compounds, whatever
they may be, are as regards the application of my process thereto considered
as real dross, and what I have already herein described in respect to the
treatment of dross, according to my process applies to the treatment of these
mätters, that is to say, impure tin and residua of working alloys may be treated
by my process as described for treating dross.
Tin Ore, properly so called.-In order to apply my process of treatment to tin
ore, properly so called, the best mode of proceeding is as follows:-First, the
tin ore, properly so called, is first brought by washings to the requisite state
for making scorice, and when in that state of richness it is roasted if it contains
too much sulphur; it is then converted into scoriæ in reducing furnaces with
or without the addition of fusing agents, according as the gangue may or may
not yield fusible glass. Now, contrary to the ordinary principles of metallurgy
it is advantageous to obtain scoriae which only melt at a high temperature.
These scoriae are then pulverized and a small quantity of charcoal is added,
and they are then converted into lumps, piled in the retorts, and subjected
when at a cherry-red heat or just under melting point to a current of hydro-
chloric acid gas. Next the products are treated and separated as before
described. It is important to seek for gold and silver in the scoriae and in the
tin which these ores yield.
Finally, it may be observed that theoretically tin ore might be reduced by
a reducing gas current without raising the temperature sufficiently high
to produce scorification the molecules of ore reduced to metal separated
from the midst of the gangue would be considered as dross or scum, and should
be acted on by hydrochloric acid gas; but practically this method offers serious
difficulty, arising from the circumstance that the metal re-oxidizes too easily,
and I greatly prefer to proceed by complete scorification.
In working I fill the retorts of the furnaces (intended to produce the hydro-
cliloric acid) as usual with chloride of sodium.
I now proceed to describe, with reference to the accompanying Drawings,
an apparatus suitable for carrying the Invention into effect. This arrangement
of apparatus consists of three apparatuses or furnaces, furnished
with retorts communicating as herein-after described; one of these
furnaces, which I call the producing furnace, is such as is ordinarily used for
the manufacture of hydrochloric acid gas, and I employ it to produce hydro-
chloric acid gas which I require for the purposes of my Invention. This
furnace is shewn in Figures 1, 2, and 3. The retorts in it communicate

page_text: with retorts in a second furnace which I call the heating furnace. In this
furnace which is shewn in Figures 4 and 5 the gas produced in the first furnace
is heated. This furnace is constructed like an ordinary furnace for producing
gas from coal, and its retorts communicate with a retort in a third furnace,
which I call the operating furnace, and which is shewn in Figure 6. In the
retort in this furnace the hydrochloric acid gas generated in the pro-
ducing furnace, and heated in the heating furnace, is brought into contact
with the lumps or stanniferous or metallic matters to be treated by means of
the said gas, I call this the operating furnace because it contains the retort in
which the operation which constitutes the subject of the present Invention is
conducted, that is to say, the operation of subjecting the lumps or metallic
matters at a high temperature to the action of hydrochloric acid gas. It may
also be called the reacting furnace or apparatus because the process may be
described as one of reaction. In all these three furnaces or apparatus the
heat must of course be duly regulated so as to maintain the temperature at
the point required.
Figure 1 is a cross section; Figure 2 a longitudinal section; and Figure 3 a
plan of the producing furnace in which the hydrochloric acid gas is generated
for the purposes of my Invention; Figure 3 also shews the arrangement of the
jars. Figure 4 is a longitudinal section, and Figure 5 cross section of the heat-
ing furnace or furnace for heating the hydrochloric acid gas before bringing it
into contact with the lumps or metallic matters to be treated. Figure 6 is a
longitudinal section of the operating furnace or apparatus in which the matters
to be treated according to this Invention are operated on by the hot hydro-
chloric acid gas.
Description of Producing Furnace.-Figures 1, 2 and 3, A, A', are cast-
iron retorts set in the furnace X. They are charged with chloride of sodium
from which hydrochloric acid gas is generated by introducing sulphuric acid all
in the usual manner. When the retorts are charged with chloride of sodium
they are closed by cast-iron covers or obturators B luted with clay. In this
cover or obturator is an orifice O, into which is fitted a tube not shown in
the Drawing, this tube terminates at top in a hopper into which the required
quantity of sulphuric acid is fed and thereby injected into and distributed over
the chloride of sodium. The obturator B', which is also luted with clay, is
not removed, it is furnished with a fire-clay tube W which is carried to and
inserted into a vessel or jar C. C, C¹, are two jars which receive the hydro-
chloric acid gas from the retorts A, A³, they are connected together by the
tube K. They are immersed in cold water, and they are also half filled with
cold water, and and they serve to retain the sulphuric acid which is carried over.

page_text: If two such jars C, C', be insufficient, a greater number may be used, if dry
bydrochloric gas be used instead of damp hydrochloric gas a drying apparatus
is placed immediately after the jars with which it communicates by pipes; D
is a tube through which the hydrochloric acid issues; E, is a tube which leads
from the tube D to the retorts F, F¹, in the heating furnace, Figures 4 and 5.
Description of Heating Furnace.-Figures 4 and 5, Y is a furnace in which
are ordinary gas retorts F, F¹, set one over the other, these retorts are filled
with fragments of fire-clay or refractory pottery sherds and the hydrochloric
acid gas brought from the furnace Figure 1 through the pipes E, H, enters
the retorts F, F1, and circulates through the fragments of fire-clay therein in
the direction indicated by the arrows, the gas first enters the retort F and
thence passes through a bent pipe V into the lower retort F¹, and it issues
therefrom through a pipe H' into the retort L, Figure 6. The retorts F, F',
are closed by fire-clay obturators luted with clay:
Description of Operating Furnace.-Figure 6, L is a fire-clay retort set in
a furnace Z. The retort L is charged with the lumps or metallic or stanniferous
matters to be treated with the hydrochloric acid gas according to my Invention.
The said gas is brought into the retort L by the pipe H' through an opening
H; M, is a fire-clay pipe which leads from the retort L into a receiver N. In
this pipe M are two openings P, Q, closed by fire-clay covers; the front cover
or obturator of the retort L, the joint between the retort and the pipe M, and
the covers of the opening P, Q, are luted with clay, through these
openings P, Q, the volatile products of the operation or bodies carried over
pass from the pipe or conductor M into the receiver N. This receiver N
is raised on a trestle or support so that when it is full it may be easily removed
from the pipe M. There are other vessels R, S, in any desired number placed
beside the receiver N to receive other products of the operation, and beyond
these vessels are other jars or vessels intended for liquefying or condensing
the hydrochloric acid gas or converting it into liquid hydrochloric acid in the
usual manner. Finally, the gaseous products which are not absorbed
are conducted to the chimney through a very long flue T, which is kept damp
for at least some portion of its length for the purpose of decomposing the
arseniated and antimoniated hydrogen, I may add that it would be possible
to allow the hydrochloric acid gas to pass from the producing furnace directly
into the operating retort L without first passing it through a heating furnace,
to reheat
but I prefer to pass it through a heating furnace so as
it before introducing it into the retort L as it is very advantageous
that the gas should pass in a heated state into the retort to act on the matters
therein for the operating retort L itself must not be heated above a certain

page_text: point lest the scoriae or scum in the lumps should be melted, for as before stated,
the said lumps should be just below smelting point while being operated upon;
but the operation is not successful unless the gas be at a high temperature;
moreover the conversion of solid metal into volatile chloride is necessarily
followed by a great reduction of temperature, hence it is highly important
that the hydrochloric acid gas should restore by its borrowed heat all or a
portion of the heat which it has absorbed during the operation; for these
reasons I recommend the employment of a separate heating apparatus as
above described.
Although I have particularly described the arrangement or combination of
apparatus which I consider most suitable for carrying my Invention into
practical effect, I wish it to be understood that I do not confine myself to
the use of this particular arrangement or combination of apparatus or
mechanical means for performing the Invention; also I do not confine myself
to the precise details which I have particularly described as the best mode
of performing the Invention though I consider such details most suitable for
the purpose, but such mechanical means or apparatus and such details may
be varied without departing from the nature of the Invention as herein set
forth.
Having now described the nature of my said Invention and in what manner
the same may be performed. I declare that I claim, the treatment of slags,
ores, and compounds of tin by subjecting them at a high temperature to the
action of hydrochloric acid gas for the purposes above specified.
In witness whereof, I, the said Joseph Jean Marcais, have hereunto set
my hand and seal, this Ninth day of November, in the year of our Lord
One thousand eight hundred and sixty-six.
Witness,
EMILE BARRAULT,
33, Bard. St. Martin.
J. J. MARCAIS. (L.S.)
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