A NEW OR IMPROVED PROCESS FOR EXTRACTING PRECIOUS METALS CON- TAINED IN THE INGOTS, THE ORES, THE MATTS, THE GOLDSMITH AND SILVER- SMITH ASHES, THE WASTES OF ALL KINDS, AND ALSO IN TILE RESIDUES OF THE AMALGAMATION
Year: 1876

page_text: LETTERS PATENT to Jean Ruch, of Paris, France, Merchant, for the Invention
of "A NEW OR IMPROVED PROCESS FOR EXTRACTING PRECIOUS METALS CON-
TAINED IN THE INGOTS, THE ORES, THE MATTS, THE GOLDSMITH AND SILVER-
SMITH ASHES, THE WASTES OF ALL KINDS, AND ALSO IN TILE RESIDUES OF THE
AMALGAMATION."
aled the 8th August 1876, and dated the 11th February 1876.
PROVISIONAL SPECIFICATION left by the said Jean Ruch at the Office of
the Commissioners' of Patents on the 11th February 1876.
JEAN RUCH, of Paris, France, Merchant. "A NEW OR IMPROVED PROCESS FOR
EXTRACTING PRECIOUS METALS CONTAINED IN THE INGOTS, THE ORES, THE MATTS,
THE GOLDSMITH AND SILVERSMITH ASHES, THE WASTES OF ALL KINDS, AND ALSO IN
THE RESIDUES OF THE AMALGAMATION."
My Invention relates to an improved process of extracting the precious metals
contained in ingots, ores, matts, gold and silver smiths' ashes, waste of all kinds,
and residues of amalgamation.
The ordinary methods of treating gold and silver smiths' ashes in reverberatory
and other furnaces necessitate the use of very high temperatures, which involve a
considerable expenditure of fuel and an appreciable loss of the metals treated.
When treated by the humid way these objections do not arise, but this method has
never hitherto been applied to the treatment of gold and silver smiths' ashes on
account of the high price of the chemical products employed, as well as of certain
difficulties in the operation.
By means of the improved process of my Invention the expenses of treatment
are reduced to an almost nominal amount as compared with the dry process, and the
operation is simple, being rendered almost automatic by the aid of the improved
apparatus which I employ, and the yield in precious metals is greater than by
fusion, and, moreover, my improved method admits of the separation and utilization
of the smallest traces of all the metals contained in the ingots, ores, matts, gold-
smiths' ashes, waste, and residues of amalgamation under treatment.
The following is the method of treating goldsmiths' ashes:-I place together in
any suitable vessel, which I will designate as A, 100 kilos. of ashes and 80 kilos. of
hydrochloric acid of commerce. Suppose the ashes to have the following com-

page_text: position, viz., gold, 200 grammes; silver, 150 grammes; copper, 5,000 gramines ;
lead, 1,000 grammes; iron, 200 grammes; tin, 200 grammes; platinum, 2 grammes.
Vessel A is put in communication with condensing receivers, which I designate
as B. By operating in a cold state in the presence of water there is formed in
vessel A chlorides of all the above-mentioned metals, with the exception of gold a
and platinum, on which hydrochloric acid has no effect.
The reaction is favored by the divided state of the material and metal, and is
accompanied by physical phenomena similar to those observed in rapid combustion
with the aid of oxygen. Those metals, such as platinum, gold, and iridium, with
which hydrochloric acid does not combine, must be subjected to the action of
nascent chlorine in order to transform them into chlorides soluble in water. To
properly attain this result I heat the vessel A containing the metallic chlorides
(previously formed in the presence of hydrochloridic acid in excess) with a body rich
in oxygen, such as the peroxides of manganese or of lead, chromic acid, and others.
I will mention, for example, nitrate of soda dissolved in water, which I employ in
the following proportions:-H Cl (80 kilos.), Na O Az 05 (31 kilos. 600 grammes)
+HO (112 kilos. 500 grammes). These proportious vary according to the com-
position of the ashes under treatment.
I produce an analogous result by mixing in suitable proportions nitrate of soda,
chloride of sodium, and alum by dissolving in nitrate of soda a salt containing
chloride of sodium in presence of a soluble sulphate, or by distilling nitric acid over
chloride of sodium or other soluble chloride. I have found by repeated experi-
ment that the presence of these neutral salts in the aqua regis does not prejudicially
affect its dissolving action. The aqua regis formed in the above manner may be
replaced by any other mixture capable of furnishing chlorine in a nascent or gazeous
state or in solution in water.
By these principal reactions above described there is produced in the solutions
containing metallic chlorides of gold, silver, copper, iron, and platinum, 1st., free
nitric acid by the action of metallic chlorides on the nitrate of soda; 2nd.,
water; 3rd., nascent chlorine, which combines with gold and platinum; 4th.,
there is evolved proto-chloride of nitro-syl or nitro-chlorous acid, Az O2 Cl, and
more especially bi-chloride of nitro-syl (hyponitro-chloric acid), Az O² Cl², which is
collected in condensers B communicating with vessel A by means of pipes, as before
mentioned.
I have found by experiment that the chlorides of nitro-syl are powerful solvents
I utilize them in subsequent
of gold, platinum, tin, regulus, and antimony.
operations, and consider them a special feature of my Invention.
I am aware that some of the above reactions are known to chemists, but my
Invention consists in their practical application for industrial purposes, which has
never hitherto been effected.
The chloruration of all the metals contained in gold and silver smiths' ashes
under treatment having been effected in the above manner, they may by reason of
their solubility be readily removed from vessel A by repeated washings. This being
effected I saturate the solutions by degrees in a wood vat with carbonate of soda
dissolved in five to six parts of water to prevent the precipitation of the gold. The
other metals are precipitated and the clear liquors are passed into another vessel.
After titrating them I dissolve with five parts of water and add a saturated solution
of sulphate of sodium. The gold precipitates in the form of a brown powder,
which is dried, collected, and calcined.
It is well known that gold in powder becomes condensed by calcination at a high
temperature. The aurate of soda or other salt of gold produced in the above
reactions and held in solution may be precipitated by a great number of substances
well known in chemistry, forming very unstable salts, or by means of acids, and
more particularly acetic acid, of which I reserve the use according to circumstances.
The chloride of gold produced in the above manner may be reduced directly by a great
number of substances, both simple and compound, and even under the influence of
heat. Reserving the use also of other reducing agents I may give as example

page_text: -
sulphuretted hydrogen, sulphurous acid, binoxide of nitrogen, arsenious acid, or
ferrous salts, whose reaction is represented by the following formula:-2 Au CP³ + 6
(SO* FeO) 2 Au + FeCl + 2 (SO³ 2FeO), and which I frequently employ
with advantage for separating the gold. Previously, however, to the reduction of
this chloride of gold I add to the liquors containing it and the other metallic
chlorides a solution of hydro-chlorate of ammonia, whereupon the platinum will be
precipitated in the form of hydro-chlorate of ammonia and platinum, which I wash
and heat slightly to bring it to a metallic state. The gold is precipitated from its
solution immediately afterwards by sulphate of iron, as before explained, the copper
being next precipitated in the metallic state by means of iron, it being only neces-
sary to melt the same to obtain it in the ingot. The silver which remains in
vessel A in the form of insoluble chloride I treat with hypo-sulphate of soda or
other solvent, and the solution is afterwards treated with sulphide of sodium, and
I thus produce pure sulphide of silver, from which the metal may be readily
separated.
In certain cases, and more particularly when treating pyritic ores, I employ as a
solvent of gold an alkaline persulphide formed with the sulphur of the pyrite and a
salt of soda. In exceptional cases I produce the alkaline persulphide according to
the ordinary methods. By dissolving in water the alkaline persulphide which has
been made to react on the pyrite under treatment, the gold remains in solution, but
by treating this solution with an acid the sulphur and gold will be precipitated
together. On exposing the precipitate to a temperature of 200 degrees centigrade
the whole of the sulphur will be quickly driven off and the gold obtained in a
perfectly pure condition.
Instead of preparing aqua regis according to the formulæ before indicated I par-
ticularly reserve the right of employing directly the following hydracids, fluorine,
bromine, iodine, either in a separate or combined state, more particularly hydro-
fluoric acid.
The gold and silver smiths' ashes after being first roasted, in order to destroy the
organic matters and consume the carbon, are placed in a lead cucurbit or other
suitable vessel provided with an escape pipe and syphon, at which the hydrofluoric
acid is introduced. The reaction first takes place at the ordinary temperature, the
silica contained in the ashes forming fluoride of silicium, which is evolved and
collected in water. The fluoride of silicium on contact with this liquid produces
hydro-fluo-silicic acid, which is afterwards decomposed by concentration or by
treating with water, so that the gelatinous silica may be separated from the solution
by decantation, leaving only the hydrofluoric acid, which is utilized in subsequent
operations. The lead cucurbit is then heated and metallic fluorides are formed by
the action of the hydrofluoric acid upon the metals contained in the ashes. These
metallic fluorides, whether of iron, copper, silver, or other metal, are removed from
the cucurbit by lixiviation and treated in the ordinary manner in order to regenerato
the hydrofluoric acid and separate the metals. The gold, platinum, and lead remain
in the cucurbit without having undergone any alteration.
After separating the gold from the platinum by the usual methods the two metals
are melted and formed into ingots. The silica, alumina, and other silicates ordi-
narily contained in these ashes may be entirely separated from the metals by means
of an alkaline carbonate, carbonate of soda for example, which converts these
several substances into soluble silicate and aluminate of soda, readily separable
from the metals by lixiviation.
In order to regenerate the acids employed in the manner above indicated I employ
oxide of magnesium or its carbonate as the precipitating agent. In this manner is
formed, as the case may be, chloride, sulphate, nitrate, or carbonate of magnesia, which
I then decompose by heating to a suitable temperature in order to set free the acids
and obtain as residue of the distillation oxide of magnesium, which is available for
future use for extraction of the acids employed in the several chemical reactions
above described.
I may also employ instead of oxide of magnesium other metallic oxides, more

page_text: especially those of barium, calcium, and strontium. To separate in the ingot the
gold from the platinum I employ an aqua regis formed of one part of nitric acid
and three parts of hydrochloric acid, chloride of gold, and chloride of platinum are
formed, and I precipitate the gold by the protosulphate of iron, and I decant and
treat the liquor with oxide of magnesium, whereby I obtain chloride of magnesium,
the platinum being precipitated.
Iridium forms with gold a ductile alloy of the color of gold. I have found that
treated with aqua regis (2 parts Az 05 + 2 parts H Cl) iridium precipitates in the
form of a black powder, and I decompose the chloride of gold by oxide of
magnesium and chloride of magnesium is formed, which is readily decomposable
by heat, and the gold precipitates.
I find by experience that in order to refine the precious metals obtained by the
different methods of my Invention, as also those of California, Australia, and other
countries, the best and most economical reagents are undoubtedly-1st., chloride-of-
nitro-syl Az O Cl (nitro-chlorous acid); 2nd., bi-chloride of nitro-syl Az O Cl³
product of the decomposition of aqua regis formed in the manner and in the pro-
portions before indicated. Thus after having collected the two chlorides of nitro-syl
in the manner before described I employ them as follows for refining the precious
metals. I place the alloy (whether gold, lead, arsenic, antimony, silver, or other)
in a large fire-clay crucible beneath a thick layer of borax, and when the metals
are melted I lower upon the crucible a dome similar to that used in the cupellation
of silver. At the centre of this dome is placed a perpendicular pipe, also of fire-
clay, which is connected by its upper end to a compressing vessel containing the
chlorides of nitro-syl, its lower end dipping into the metals in fusion. Immediately
said metals are raised to the required temperature I force by pressure the dessicated
chlorides of nitro-syl into the metallic bath through the pipe, whereupon volatile
chlorides immediately form, which may either be allowed to escape or may be
collected by providing pipes at each end of the dome for conducting the gases and
vapors into a condenser, or these pipes may simply serve to carry away to the
chimney the volatile products evolved in the crucible, which contain lead, antimony,
and copper in the form of chloride.
I reserve the right, if convenient, of introducing into the crucible a current of
cold or heated air, or it may be steam or hydrogen, in order to produce such
The chloride of silver is recovered in
oxidation or reduction as may be desirable.
the borax, and there is no loss of gold, whose chloride could not exist at this tem-
perature. In order to reduce the silver the borax charged with chloride of silver is
placed between two iron plates in water acidulated with sulphuric acid.
I have found that the two chlorides of nitro-syl, Az O Cl and Az O C12, when
well dried or heated act energetically upon iron and transform it into perchloride of
iron Fe Cl³, which, with the assistance of air and water, acts strongly upon
metallic sulphates, arsenurets, and antimonurets, and inore particularly on iron and
copper pyrites and galena. The perchloride of iron is reduced in the reaction to the
state of protochloride of iron Fe Cl, while the metals are transformed into chlorides,
which are lixiviated with a weak solution of sea salt, and then decomposed in the
manner before described.
SPECIFICATION in pursuance of the conditions of the Letters Patent filed by the
said Jean Ruch in the Great Seal Patent Office on the 9th August 1876.
JEAN RUCH, of Paris, France, Merchant. "A NEW OR IMPROVED PROCESS FOR
EXTRACTING PRECIOUS METALS CONTAINED IN THE INGOTS, THE ORES, THE MATTS,
THE GOLDSMITH AND SILVERSMITH ASHES, THE WASTES OF ALL KINDS, AND ALSO IN
THE RESIDUES OF THE AMALGAMATION."
My Invention relates to an improved process of extracting the precious metals

page_text: contained in ingots, ores, matts, goldsmiths' and silversmiths' ashes, waste of all
kinds and residues of amalgamation.
The ordinary methods of treating gold and silver smiths' ashes in reverberatory
and other furnaces necessitate the use of very high temperatures, which involve a
considerable expenditure of fuel and appreciable loss of the metals treated.
When
treated by the humid way these objections do not arise, but this method has never
hitherto been applied to the treatment of gold and silver smiths' ashes on account
of the high price of the chemical products employed, and in consequence of certain
difficulties in the operation.
By means of the improved process of my Invention the expenses of treatment
are reduced to an almost nominal amount as compared with the cost of the dry
process, and the operation is simple, being rendered almost automatic by the aid of.
the improved apparatus which I employ, and the yield in precious metal is greater
than that obtained by fusion. Moreover, my improved method admits of the
separation and utilization of the smallest traces of all the metals contained in the
ingots, ores, matts, goldsmiths' ashes, waste, and residues of amalgamation under
treatment.
The following is the method of treating gold and silver smiths' ashes:-I place
together in any suitable vessel, which I will designate as A, 100 kilogrammes of
ashes and 80 kilogrammes of hydrochloric acid of commerce. Suppose the ashes to
have the following composition, viz., gold, 200 grammes; silver, 150 grammes;
copper, 5,000 grainmes; lead, 1,000 grammes; iron, 200 grammes; tin, 200
grammes; platinum, 2 grammes; lime loam (silica and alumina), silicates soluble
in acids, &c. Vessel A is put in communication with condensing receivers, which I
designate as B. By operating in a cold state in the presence of water there is
formed in vessel A chlorides of all the above-mentioned inetals (with the exception
of gold and platinum), which, as well as the chloride of calcium and the silicates
soluble in hydrochloric acid, are eliminated by washing.
The reaction is favored by the divided state of the material and metal, and is
accompanied by physical phenomena similar to those observed in rapid combustion
in the presence of oxygen. Those metals, such as platinum, gold, iridium, &c., with
which hydrochloric acid does not combine, must be subjected to the action of nascent
chlorine in order to transform them into chlorides soluble in water. To properly
attain this result I heat the vessel A (after having placed therein a substance rich
in oxygen, such as the peroxide of manganese or of lead, chromic acid, nitrate of
soda or potash, &c., &c.) by means of a furnace or by steam or hot air brought into
contact with the matters. I employ the following proportions:-H Cl (80 kilo-
grammes), Na O Az 05 (31 kilogrammes 600 grammes) + HO (112 kilogrammes
500 gramines). These proportions, however, vary according to the composition of
the ashes under treatment.
I produce an analogous result by mixing in suitable proportions nitrate of soda,
chloride of sodium and alum, or by dissolving in nitrate of soda a salt containing
chloride of sodium in presence of a soluble sulphate, or by distilling nitric acid over
chloride of sodium or other soluble chloride. I have found by repeated experiment
that the presence of these neutral salts in the aqua regia does not prejudicially affect
its dissolving action. The aqua regia formed in the above manner may be replaced
by any other mixture or decomposition by heat or otherwise, capable of furnishing
chlorine in a nascent or gaseous state, or in solution in water.
By the principal reactions above described there is finally produced chlorides of
gold, silver, platinum, &c., and there is evolved proto-chloride of nitro-syl or
nitro-chlorous acid, Az O Cl, and more especially bi-chloride of nitro-syl (hypo-
chloro-nitric acid), Az O2 C, which is collected in the condensers B communicating
with vessel A by means of pipes, as before mentioned.
I have found by experiment that the chlorides of nitro-syl are powerful solvents
of gold, platinum, tin, regulus of antimony, &c., &c., and I utilize them in sub-
sequent operations, and consider them a special feature of my Invention.
I am aware that some of the above reactions are known to chemists, but my

page_text: Invention consists in their practical application for the extraction of precious metals
which has never hitherto been effected, nor has the property possessed by the two
compounds Az O CI and Az 0 CP of readily dissolving gold, silver, platinum,
copper, and all other metals ever before been utilized.
The chloruration of the gold, silver, platinum, &c., under treatment having been
effected in the above manner the chlorides may be readily removed from vessel A by
repeated washings. This being effected I saturate the solutions by degrees in a
wood vat or other suitable vessel by known means in order to separate the gold
from the platinum. The silver which remains in the state of insoluble chloride is
treated with any suitable solvent, hyposulphite of soda for example. The solution
is then treated with sulphate of sodium, and I thus produce pure sulphide of silver,
from which the metal is easily separated.
-
In certain cases, and more particularly when treating pyritic ores, I employ as a
solvent of gold an alkaline persulphide formed with the sulphur of the pyrite and a
salt of soda. In exceptional instances I produce the alkaline persulphide according
to the ordinary methods. By dissolving in water the alkaline persulphide which
has been made to react on the pyrite under treatment the gold remains in solution,
but by treating this solution with an acid the sulphur and gold will be precipitated
together. On exposing this precipitate to a temperature of 200 degrees cent. the
whole of the sulphur will be quickly driven off and the gold obtained in a perfectly
pure condition.
Instead of preparing an aqua regia according to the formulæ before indicated I
particularly reserve the right of employing directly the following hydracids:-
Fluorine, bromine, iodine, either in a free or combined state, more particularly
hydrofluoric acid, which I utilize in the following manner:-
The gold and silver smiths' ashes are placed in a lead cucurbit or other suitable
vessel provided with an escape pipe and syphon, at which the hydrochloric acid is
introduced. The reaction first takes place at the ordinary temperature, the silica
contained in the ashes (whether combined silica or not) forming fluoride of- silicium,
which is evolved and collected in water. The fluoride of silicium on contact with
this liquid produces hydro-fluo-silicic acid, which is afterwards decomposed by con-
centration or by treating with water, so that the gelatinous silica may be separated
from the solution by decantation, leaving only the hydrofluoric acid, which is
utilized in subsequent operations. The lead cucurbit is then heated, and metallic
fluorides are formed by the action of the hydrofluoric acid upon the metals con-
tained in the ashes. These metallic fluorides are for the most part removed from
the cucurbit by lixiviation and treated in the ordinary manner in order to regenerate
the hydrofluoric acid and separate the metals. The gold, platinum, and lead remain
in the cucurbit without having undergone any alteration.
After separating the gold from the platinum by the usual methods the two metals
aro melted and formed into ingots. The quartz, silica, alumina, lime, &c., contained
in certain ores, and nearly always in these ashes, may be entirely separated from the
precious and other metals by means of an alkaline chloride, sulphate, carbonate, or
nitrate (potash, soda, lime, &c.), which I decompose by means of carbon and steam
at a suitable temperature, so as to form with the silicious gangue of the ore or the
free or combined silica of the ashes alkaline silicates and aluminates, soluble in
water and readily separable from the metals by lixiviation. For example, supposing
it is desired to treat a silicious ore containing 57 per cent. of silica, 8 per cent. of
copper, 10 per cent. of lead, 15 per cent. of silver, 5 per cent. of iron, and 5 per
cent. of gold, I melt this silicious ore (or goldsmiths' ashes having a similar com-
position) with sulphate of soda or of potash in the proportion of two equivalents of
sulphate of soda and four equivalents of carbon for each equivalent of silica con-
I thus
tained in the ore or ashes from which the metals are to be extracted.
produce silicate of soda, and all the metals pass to the state of sulphides with the
exception of the gold. Then by the aid of steam introduced on the surface of the
matters in fusion I decompose the metallic sulphides and the sulphide of sodium in
excess which pass into the state of oxides, and are then reduced to the metallic

page_text: state by the addition of a certain quantity of carbon or other reducing agent.
During the first stage of the operation there is evolved a mixture of vapors of
sulphur, sulphurous acid, and carbonic oxide, and towards the end of the operation
sulphuretted hydrogen is formed under the influence of the steam, which volatilizes
while the metals oxidize, and are lastly reduced, as before mentioned, and separated
from the silicate and aluminate of soda by lixiviation.
I find by experience that in order to refine the precious metals obtained by the
different methods of my Invention, as also those of California, Australia, Chili,
Senegal, and other countries the best reagents are undoubtedly, 1st., chloride of
nitro-syl Az O Cl (nitro-chlorous acid); 2nd., bi-chloride of nitro-syl Az Oº CI²,
product of the decomposition of the aqua regia formed in the manner and in the
proportions before indicated. After having collected the two chlorides of nitro-syl
in the manner before described I employ them as follows for refining the precious
metals I place the alloy (whether gold, lead, arsenic, antimony, silver, &c.) in a
large fire-clay crucible lined with porcelain enamel in order to render the same
impervious to the chloride of silver, which, instead of passing through the pores of
the crucible, is to be wholly volatilized. When the metals are melted I lower
upon the crucible a dome similar to that used in the cupellation of silver. At the
centre of this dome is placed a perpendicular pipe of fire-clay, which is connected
by its upper end to a compressing vessel containing the chlorides of nitro-syl, its
lower end dipping into the metals in fusion. Immediately these metals are raised
to the required temperature I force by compression the desiccated chlorides of
nitro-syl through the pipe into the metallic bath, whereupon volatile chlorides are
immediately formed, and escape with the chloride of silver, and are collected by
means of pipes leading from each end of the dome into a condensing chamber for the
gases and vapors evolved in the crucible containing the matters in fusion, on which
the chlorides of nitro-syl react energetically to produce the above-mentioned results.
From this condenser the chlorides of antimony, arsenic, sulphur, are carried away to
the chimney, and ultimately mix with the products of combustion escaping into the
atmosphere.
I reserve the right if convenient of introducing into the crucible a current of
cold or heated air, or it may be steam or hydrogen, in order to produce such
oxidating or reducing effect as may be desirable. There is no loss of gold, as the
chloride of this metal could not exist at the above temperature.
Having described the nature of my Invention and the manner of performing the
same, I declare that what I claim as the Invention to be protected by the herein-
before in part recited Letters Patent is,―
First. The employment of an aqua regia formed in the manner and in the pro-
portions herein-before indicated to act on and transform into chlorides the precious
and other metals contained in ingots, ores, matts, gold and silver smiths' ashes,
waste of all kinds, and residues of amalgamation.
Second. The production and utilization for the purposes of treating precious and
other metals of the two chlorides of nitro-syl, represented by the formulæ Az O° Cl
and Az O CP².
Third. The employment of chlorine in a nascent or other state mixed with hydro-
chloric or other mineral acids, for the chloruration of metals, more particularly gold
and platinum.
Fourth. The employment in the manner indicated of alkaline persulphides for
acting on and dissolving the gold contained in pyritic and other ores or ashes.
Fifth. The employment of hydrofluoric and hydro-fluo-silicic acids for forming
with the gangue of silicious ores or the silica of goldsmiths' ashes, fluorides of
silicium, and metallic fluorides, also the mode of decomposing the same.
Sixth. The employment of alkaline chlorides, sulphates, carbonates, and nitrates
(potash, soda, lime, baryta, &c.) decomposable by carbon and steam, atmospheric air,
or oxygen, in order to form with the silica of the ores or goldsmiths' ashes, alkaline
silicates soluble in water or acids, more particularly in hydrochloric acid.
Seventh. The employment of the two chlorides of nitro-syl Az O Cl and Az O° Cl³

page_text: for refining precious and other metals in the apparatus herein-before described, or
in any other suitable apparatus.
Eighth. The employment for refining the precious metals with chlorine or the two
chlorides of nitro-syl Az O2 Cl and Az O Cl² of fire-clay, plumbago, or other
crucibles lined internally with vitrifiable substances, such as porcelain, silicates,
whether double or multiple, crystal, &c., in order to prevent the chloride of silver
penetrating the pores of the crucible, and thus enable the whole to be volatilized
and collected in the condenser, as herein-before specified.
Ninth. The employment a sa precipitating agent of oxide of magnesium or its car-
bonate in order to form, as the case may be, either chloride, sulphate, carbonate, or
nitrate of magnesia, which is then decomposed by heat at a suitable temperature for
freeing the acids and obtaining as a fixed residue of the distillation oxide of
magnesium, which serves indefinitely for the extraction of acids employed in the
several chemical reactions herein-before mentioned.
Tenth. The employment in place of oxide of magnesium of other metallic oxides,
especially oxide of barium or its hydrate, oxide of calcium, or strontium, &c.
In witness whereof, I, the said Jean Ruch, have hereunto set my hand and
seal, this First day of August, in the year of our Lord One thousand eight
hundred and seventy-six.
I RUCHT 101