Lead combinations give the following reactions before the blowpipe:

Metallic lead tarnishes when heated in the oxidation flame, and is

instantly covered with a grey matter, consisting of the protoxide and

the metal. It fuses quickly, and is then covered with a

yellowish-brown protoxide until all the lead is converted into the

protoxide, which melts to a yellow liquid. In the reduction flame and

upon charcoal, it is volatilized, while the charcoal becomes covered

with a yellow sublimate of oxide. A little distance from the assay,

this sublimate appears white (carbonate of lead). Protoxide of lead

melts in the flame of oxidation to a beautiful dark yellow bead. In

the flame of reduction, and upon charcoal, it is reduced with

intumescence to metallic lead, which is volatilized by a continued

blast, and sublimates on charcoal, as mentioned above.

Red oxide of lead turns black when heated in the glass tube closed at

one end, and liberates oxygen, which is easily detected by the

introduction of an ignited splinter, when a more lively combustion of

the wood proves the presence of uncombined oxygen. The red oxide in

this case is reduced to the protoxide. Heated upon platinum foil, it

first turns black, is reduced to the protoxide, and melts into a dark

yellow liquid. In the reduction flame, upon charcoal, it is reduced to

the metal with intumescence. After a continued blast, a yellow

sublimate of protoxide is produced upon the charcoal, and at a little

distance off, around this sublimate, a white one of carbonate of lead

is produced. This sublimate disappears when touched by the flame of

reduction, while it communicates an azure blue-tinge to the external

flame. This is likewise the case with the peroxide of lead.

The different oxides of lead produce with the blowpipe reagents the

same reactions.

_Borax_ dissolves lead compounds with the greatest readiness upon

platinum wire in the oxidation flame to a transparent bead, which is

yellow when hot, but colorless after being cooled. With the addition

of more of the lead oxide, it becomes opalescent. When heated by the

intermittent flame, and with still more of the oxide, it acquires a

yellow enamel after cooling. Heated upon charcoal, in the flame of

reduction, the bead spreads and becomes opaque. After a continued

blast, all the oxide is reduced with effervescence to metallic lead,

which melts and runs towards the edges of the bead, while the bead

again becomes transparent.

_Microcosmic Salt_ dissolves oxides of lead upon platinum wire in the

flame of oxidation easily to a clear, colorless bead, which appears,

when highly saturated, yellow while hot. A saturated bead becomes

enamel-like after cooling. The bead appears in the flame of reduction,

and upon charcoal, of a greyish color and dull. By the addition of

more oxide, a yellow sublimate of protoxide is produced upon the

charcoal. By the addition of tin, the bead appears of a darker grey,

but it is never quite opaque.

_Carbonate of Soda_ dissolves oxide of lead in the flame of oxidation

upon platinum wire quite readily to a transparent bead, which becomes

yellow when cooling, and is opaque. Upon charcoal in the flame of

reduction, it is rapidly reduced to metallic lead, which yields,

after a continued blast, a yellow sublimate of oxide upon the

charcoal.

(_b._) _Bismuth_ (Bi).--This metal occurs mostly in the metallic

state, and less frequently as the sulphide. In the pure metallic

state, it is of a reddish-white color and great lustre. It

crystallizes in cubes. It is brittle, and may be readily pulverized.

It melts at 476°, and is volatilized at a white heat. It is soluble in

nitric acid, and forms the nitrate of bismuth.

([alpha].) _Oxide of Bismuth _(Bi^{2}O^{3}).--This oxide is a light

yellow powder, fusible at a red heat, insoluble in caustic potash and

ammonia. It is the base of the salts of bismuth. Its hydrate is white,

and easily soluble in acids. The addition of water causes these

solutions to become milky, because they are decomposed into a soluble

acidulous and an insoluble basic salt of bismuth.

([beta].) _Peroxide of Bismuth_ (BiO^{2}) is a dark-colored powder,

completely soluble in boiling nitric acid, and yielding oxygen;

produces, with hydrochloric acid, chlorine gas. It can be heated up to

the temperature of 620° without being decomposed; but, exposed to a

temperature of 630° it yields oxygen. Mixed with combustible

substances, it glows with brightness.

([gamma].) _Bismuthic Acid _(Bi^{2}O^{5}) is a brown powder similar to

the peroxide, but is converted by boiling nitric acid into a green,

scarcely soluble substance (Bi^{2}O^{3}, Bi^{2}O^{5}). Its hydrate is

of a red color.

BLOWPIPE REACTIONS.--Metallic bismuth is converted, when exposed upon

platinum wire to the flame of oxidation, into a dark brown oxide,

which turns light yellow while cooling. It is slowly volatilized when

heated, and a yellow sublimate of oxide is produced upon the charcoal.

Oxide of bismuth melts upon platinum foil in the flame of oxidation

very easily into a dark-brown liquid, which changes to a light yellow

while cooling. By too strong a heat, it is reduced and penetrates the

platinum foil.

Upon charcoal, in the flame of oxidation and of reduction, it is

reduced to metallic bismuth, which melts into one or more globules.

By a continued blast they are slowly volatilized, and produce a yellow

sublimate of oxide upon the charcoal, beyond which a white sublimate

of carbonate of bismuth is visible. These sublimates disappear in the

flame of reduction, but without communicating any color to it.

_Borax_ dissolves oxide of bismuth upon platinum wire, in the flame of

oxidation, easily to a clear yellow bead, which appears colorless

after cooling. By the addition of more oxide, the hot bead becomes

orange. It turns more yellow while cooling, and when cool is

opalescent. Upon charcoal in the flame of reduction, the bead becomes

turbid and greyish colored. The oxide is reduced with intumescence to

the metallic state, and the bead becomes clear again. The addition of

tin promotes the reduction.

_Microcosmic Salt_ dissolves oxide of bismuth upon platinum wire, in

the flame of oxidation, to a yellow bead, which becomes colorless

after cooling. By the addition of more oxide, the bead is

yellowish-brown while hot, and colorless after cooling, but not quite

transparent. This bead becomes enamelled when heated by the

intermittent flame; also, by the addition of still more of the oxide,

after it is cooled.

Upon charcoal, in the flame of reduction, and particularly with the

addition of tin, the bead is colorless and transparent while hot, but

while cooling becomes of a dark-gray color and opaque.

Oxide of bismuth is reduced, by fusion with carbonate of soda, as well

in the oxidating as in the reducing flame, instantly to metallic

bismuth.

As the above mentioned higher oxides of bismuth are converted by

ignition into oxide of the metal and free oxygen, they have the same

behavior before the blowpipe.

As bismuth occurs mostly in the metallic form, it is necessary to know

how to distinguish it from metals similar to it. Its brittleness

distinguishes it from lead, zinc and tin, as they are readily

flattened by a stroke of the hammer, while bismuth is broken to

pieces. Bismuth, in this latter respect, might perhaps be mistaken

for antimony or tellurium; but, by the following examination, it is

easy to separate bismuth from antimony or tellurium.

1. Neither bismuth nor antimony sublimates when heated in a glass tube

closed at one end. At a temperature which is about to fuse the glass,

tellurium yields a small quantity of a white vapor (some tellurium is

oxidized to tellurous acid by the oxygen of the air in the tube).

After that, a grey metallic sublimate settles on the sides of the

tube.

2. Heated in an open tube, antimony yields a white vapor, which coats

the inside of the glass tube, and can be driven by heat from one part

of the tube to another without leaving a residue. The metallic globule

is covered with a considerable quantity of fused oxide. Tellurium

produces, under the same circumstances, an intense vapor, and deposits

on the glass a white powder, which melts by heat into globules that

run over the glass. The metallic globules are covered by fused,

transparent, and nearly colorless oxide, which becomes white while

cooling. By a high temperature, and with little access of air,

metallic tellurium sublimes with the deposition of a grey powder.

Bismuth produces, under similar treatment, scarcely any vapor, unless

it is combined with sulphur. The metal is enveloped by fused oxide of

a dark yellow color, which appears light yellow after being cooled. It

acts upon the glass, and dissolves it.

3. Upon charcoal, exposed to the blowpipe flame, the three metals are

volatilized, and yield a sublimate upon the charcoal. That of antimony

is white, while those of bismuth and tellurium are dark yellow. By

exposing them to the flame of reduction, the sublimate of tellurium

disappears and communicates an intense green color to the flame. The

antimony incrustation gives a feeble greenish-blue color, while the

sublimate of bismuth gives no perceptible color in the light. It is,

however, worthy of notice that if the operation takes place in the

dark, a very pale blue flame will be seen with the bismuth.

(_c._) _Tin_ (Sn).--This metal does not occur in nature in the

metallic state, very seldom in the sulphide, but chiefly in the oxide

(tinstone). In the metallic state it is silver-white, possesses a very

high lustre, is soft (but harder than lead), ductile, but has not much

tenacity, and it is very malleable. The metal when it is cast gives a

peculiar creaking noise when twisted or bent, which proceeds from the

crystalline structure of the metal. This crystallization is quite

clearly manifested by attacking the surface of the metal, or that of

tin plate, with acids.

Tin is very slightly tarnished by exposure to the air. It fuses at

442°, and becomes grey, being a mixture of the oxide and the metal. At

a high temperature even, tin is but little subject to pass off as

vapor. It is soluble in aqua regia, and with the liberation of

hydrogen, in hot sulphuric and hydrochloric acids, and in cold dilute

nitric acid, without decomposing water, or the production of a gas,

while nitrate of tin and nitrate of ammonia are formed. Concentrated

nitric acid converts tin into insoluble tin acids.

([alpha].) _Protoxide of Tin_ (SnO) is a dark-grey powder. Its hydrate

is white, and is soluble in caustic alkalies. When this solution is

heated, anhydrous crystalline black protoxide is separated. The

soluble neutral salts of tin-protoxide are decomposed by the addition

of water, and converted into acid soluble, and basic insoluble salts.

When protoxide of tin is ignited with free access of air, it takes

fire and is converted with considerable intensity into the acids,

producing white vapors. This is likewise the case if it is touched by

a spark of fire from steel. The hydrate of the protoxide of tin can be

ignited by the flame of a candle, and glows like tinder.

([beta].) _Sesquioxide of Tin_ (Sn^{2}O^{3}) is a greyish-brown

powder. Its hydrate is white, with a yellow tinge. It is soluble in

aqua ammonia and in hydrochloric acid; this solution forms with

solution of gold the "purple of Cassius."

([gamma].) _Stannic Acid_ (peroxide, SnO^{2}).--This acid occurs in

nature crystallized in quadro-octahedrons, of a brown or an intense

black color, and of great hardness (tinstone). Artificially prepared,

it is a white or yellowish-white powder. It exists in two distinct or

isomeric modifications, one of which is insoluble in acids (natural

tin-acid) while the other (tin-acid prepared in the wet way) is

soluble in acids. By ignition the soluble acid is converted into the

insoluble. Both modifications form hydrates.

_Reactions before the Blowpipe._--Metallic tin melts easily. It is

covered in the flame of oxidation into a yellowish-white oxide, which

is carried off sometimes by the stream of air which propels the flame.

In the reduction flame, and upon charcoal, melting tin retains its

metallic lustre, while a thin sublimate is produced upon the charcoal.

This sublimate is light-yellow while hot, and gives a strong light in

the flame of oxidation, and turns white while cooling. This sublimate

is found near to the metal, and cannot be volatilized in the oxidation

flame. In the flame of reduction it is reduced to metallic tin.

Sometimes this incrustation is so imperceptible that it can scarcely

be distinguished from the ashes of the charcoal. If such be the case,

moisten it with a solution of cobalt, and expose it to the flame of

oxidation, when the sublimate will exhibit, after cooling, a

bluish-green color.

Protoxide of tin takes fire in the flame of oxidation, and burns with

flame and some white vapor into tin acid, or stannic acid. In a strong

and continued reduction flame, it may be reduced to metal, when the

same sublimate above mentioned is visible. The sesquioxide of tin

behaves as the above.

Stannic acid, heated in the flame of oxidation, does not melt and is

not volatilized, but produces a strong light, and appears yellowish

while hot, but changing as it cools to a dirty-yellow white color. In

a strong and continued flame of reduction, it may be reduced likewise

to the metallic state, with the production of the same sublimate as

the above.

_Borax_ dissolves tin compounds in the flame of oxidation, and upon

platinum wire, very tardily, and in small quantity, to a transparent

colorless bead, which remains clear after cooling, and also when

heated intermittingly. But if a saturated bead, after being completely

cool, is exposed again to the flame of oxidation, at a low red heat,

the bead while cooling is opaque, loses its globular form, and

exhibits an indistinct crystallization. This is the case too in the

flame of reduction, but if the bead is highly saturated, a part of the

oxide is reduced.

_Microcosmic Salt_ dissolves the oxides in the flame of reduction very

tardily in a small quantity to a transparent colorless bead, which

remains clear while cooling. If to this bead sesquioxide of iron is

added in proper proportion, the sesquioxide loses its property of

coloring the bead, but of course an excess of the iron salt will

communicate to the bead its own characteristic color. In the flame of

reduction no further alteration is visible.

Tin-oxides combine with carbonate of soda, in the flame of oxidation

upon platinum wire, with intumescence to a bulky and confused mass,

which is insoluble in more soda. Upon charcoal, in the reduction

flame, it is easily reduced to a metallic globule. Certain compounds

of tin-oxides, particularly if they contain tantalum, are by fusion

with carbonate of soda reduced with difficulty; but by the addition of

some borax, the reduction to the metallic state is easily effected.

Tin-oxides exposed to the oxidation flame, then moistened with a

solution of cobalt, and exposed again to the flame of oxidation, will

exhibit, after having completely cooled, a bluish-green color.

EIGHTH GROUP.--MERCURY, ARSENIC.

These two metals are volatilized at a temperature lower than that of a

red heat, and produce, therefore, no reactions with borax and

microcosmic salt. Their oxides are easily reduced to the metallic

state.

(_a._) _Mercury_ (Hg).--This metal occurs in nature chiefly combined

with sulphur as a bisulphide.

It occurs still more rarely in the metallic form, or combined with

silver, selenium, or chlorine.

Mercury, in the metallic state, has a strong lustre, and is liquid at

ordinary temperatures, whereby it is distinguished from any other

metal. It freezes at 40° and boils at 620°, but it evaporates at

common temperatures. Pure mercury is unalterable. Upon being exposed

to the air, it tarnishes only by admixture with other metals, turns

grey on the surface, and loses its lustre. It is soluble in cold

nitric acid and in concentrated hot sulphuric acid, but not in

hydrochloric acid.

([chi].) _Protoxide of Mercury_ (Hg^{2}O).--It is a black powder,

which is decomposed by ignition into metallic mercury and oxygen. By

digestion with certain acids, and particularly with caustic alkalies,

it is converted into metallic mercury and peroxide. Some neutral salts

of the protoxide are only partly soluble in water, as they are

converted into basic insoluble and acid soluble salts.

Protoxide of mercury is completely insoluble in hydrochloric acid. Its

neutral salts change blue litmus paper to red.

([beta].) _Peroxide of Mercury_ (HgO).--This oxide exists in two

allotropic modifications. One is of a brick-red color, and the other

is orange. Being exposed to heat, they turn black, but regain their

respective colors upon cooling. They are decomposed at a high

temperature into metallic mercury and oxygen. They yield with acids

their own peculiar salts.

Mercury, in the metallic form, can never be mistaken for any other

metal in consequence of its fluid condition at ordinary temperatures.

Exposed to the blowpipe flame, it is instantly volatilized. This is

also the case with it when combined with other metals. The oxides of

mercury are, in the oxidation and reduction flames, instantly reduced

and volatilized. They do not produce any alteration with fluxes, as

they are volatilized before the bead melts. Heated with carbonate of

soda in a glass tube closed at one end, they are reduced to metallic

mercury, which is volatilized, and condenses upon a cool portion of

the tube as a grey powder. By cautious knocking against the tube, or

by rubbing with a glass rod, this sublimate can be brought together

into one globule of metallic mercury. Compounds of mercury can be most

completely reduced by a mixture of neutral oxalate of potassa and

cyanide of potassium. If the substance under examination contains such

a small quantity of mercury that it cannot be distinguished by

volatilization, a strip of gold leaf may be attached to an iron wire,

and introduced during the experiment in the glass tube. The smallest

trace of mercury will whiten the gold leaf in spots.

(_b._) _Arsenic_ (As).--This metal occurs in considerable quantity in

nature, chiefly combined with sulphur or metals.

Arsenic, in the metallic state, is of a whitish-grey color, high

lustre, and is crystalline, of a foliated structure, and is so brittle

that it can be pulverized. It does not melt, but is volatilized at

356°. Its vapor has a strong alliaceous odor. Arsenic sublimes in

irregular crystals. By exposure to the air it soon tarnishes, and is

coated black. Being mixed with nitrate of potassa and inflamed, it

detonates with vehemence. Mixed with carbonate of potassa, it is

inflamed by a stroke of the hammer, and detonates violently.

Heated in oxygen gas, it is inflamed, and burns with a pale blue flame

to arsenious acid.

([beta].) _Arsenious Acid_ (AsO^{3}).--This acid crystallizes in

octahedrons, or, when fused, forms a colorless glass, which finally

becomes opaque and enamel-like, or forms a white powder. It sublimes

without change or decomposition. When heated for a longer while below

the temperature of sublimation, it melts into a transparent,

colorless, tough glass. The opaque acid is sparingly soluble in cold

water, and still more soluble in hot water. It is converted, by

continued boiling, into the transparent acid, which is much more

soluble in water. Arsenious acid is easily dissolved by caustic

potassa. It is also soluble in hydrochloric acid. This acid occurs

associated with antimonious acid, protoxide of tin, protoxide of lead,

and oxide of copper. It occurs likewise in very small quantity in

ferruginous mineral springs.

([gamma].)_Arsenic Acid_ (AsO^{5}) is a white mass, which readily

absorbs moisture and dissolves. It will not volatilize at a low red

heat, nor will it decompose. Exposed to a strong heat, it is

decomposed, yielding oxygen, and passing into arsenious acid.

_Reactions before the Blowpipe._

Metallic arsenic, heated in a glass tube closed at one end, yields a

black sublimate of a metallic lustre, and at the same time gives out

the characteristic alliaceous odor. This is the case too with alloys

of arsenic, if there is a maximum quantity of arsenic present.

When heated in a glass tube open at both ends, metallic arsenic is

oxidized to arsenious acid, which appears as a white crystalline

sublimate on the sides of the glass tube. This deposit will occur at

some distance from the assay, in consequence of the great volatility

of the arsenic. The sublimate can be driven from one place upon the

tube to another, by a very low heat. Alloys of arsenic are converted

into basic arseniates of metal oxides, while surplus arsenic is

converted into arsenious acid, which sublimes on the tube. If too much

arsenic is used for this experiment, a dark-brown incrustation will

sublime upon the sides of the tube which will give an alliaceous

smell. If this sublimate should be deposited near the assay, then it

resembles the white sublimate of arsenious acid.

Heated upon charcoal, metallic arsenic is volatilized before it melts,

and incrusts the charcoal in the flame of oxidation as a white deposit

of arsenious acid. This sublimate appears sometimes of a greyish

color, and takes place at some distance from the assay. When heated

slightly with the blowpipe flame, this sublimate is instantly driven

away, and being heated rapidly in the reduction flame, it disappears

with a light blue tinge, while the usual alliaceous or garlic smell

may be discerned.

Arsenious acid sublimes in both glass tubes very readily, as a white

crystalline sublimate. These crystals appear to be regular octahedrons

when observed under the microscope. Upon charcoal it instantly

volatilizes, and when heated, the characteristic garlic smell may be

observed.

Arsenic acid yields, heated strongly in a glass tube closed at one

end, oxygen and arsenious acid, the latter of which sublimes in the

cool portions of the tube. Compounds of arsenic produce, in

consequence of their volatility, no reactions with fluxes. Being

heated upon charcoal with carbonate of soda, they are reduced to

metallic arsenic which may be detected by the alliaceous odor peculiar

to all the arsenic compounds when volatilized.

NINTH GROUP.--COPPER, SILVER, GOLD.

These metals are not volatile, neither are their oxides. They are

reduced to the metallic state, by fusion with carbonate of soda, when

they melt to a metallic grain. The oxides of silver and gold are

reduced _per se_ to the metallic state by ignition. In the reduction

of the oxides of this group, no sublimate is visible upon the

charcoal.

(_a._) _Copper_ (Cu).--This metal occurs in the metallic state, also

as the protoxide, and as oxides combined with acids in different salts

(carbonate of copper as malachite, etc.) The sulphide of copper is the

principal ore of copper occurring in nature. In the metallic state,

copper is of a red color, has great lustre and tenacity, is ductile

and malleable, and crystallizes in octahedrons and cubes. It melts at

a bright red heat, is more difficult than silver to fuse, but fuses

more readily than gold. It absorbs oxygen while melting. There arises

from its surface a fine dust of metallic globules, which are covered

with the protoxide. The surface of the metal is likewise covered with

the protoxide. Copper exposed to moist air tarnishes, and is

converted into hydratic carbonate of copper. When ignited in the open

air, it is soon covered with the brownish-red protoxide.

([chi].) _Protoxide of Copper_ (Cu^{2}O).--This oxide occurs in

nature, crystallized in octahedrons of a ruby-red color, of a lamellar

structure, and transparent. Artificially prepared, it forms a powder

of the same color. It is decomposed by dilute acids into salts of

peroxide and metal. It is converted by ignition, with free access of

air, into peroxide.

([beta].) _Oxide of Copper_ (CuO).--This oxide is a dark-brown or

black powder. It is dissolved by acids, with a blue or green-colored

solution. It is soluble in aqua ammonia, and the solution is of a dark

blue color.

_Reactions before the Blowpipe._--Oxide of copper exposed upon

platinum wire to the inmost flame (the blue flame), communicates to

the external flame a green color. Heated upon charcoal in the

oxidation flame, it melts to a black ball, soon spreads over the

charcoal, and is partially reduced.

Exposed to the reduction flame, at a temperature which will not melt

copper, it is reduced with a bright metallic lustre, but as soon as

the blast ceases, the surface of the metal becomes oxidized, and

appears dark brown or black. If the temperature is continued still

higher, it melts to a metallic grain.

_Borax_ dissolves the oxide of copper in the flame of oxidation to a

clear green-colored bead, even if the quantity of oxide be quite

small, but by cooling, the bead becomes blue. In the flame of

reduction upon platinum wire, the bead soon becomes colorless, but

while cooling presents a red color (protoxide of copper). This bead is

opaque, but, if too much of the oxide is added, a part of it is

reduced to metal, which is visible by breaking the metallic grain.

Upon charcoal, the oxide is reduced to the metal, and the bead appears

colorless after cooling. With the addition of some tin, the bead

becomes brownish-red and opaque after cooling.

_Microcosmic Salt_ dissolves oxide of copper in the flame of oxidation

to a green bead, not so intensely colored as the borax bead. In the

reduction flame the bead, if pretty well saturated, becomes dark-green

while hot, and brownish-red when cool, opaque and enamel-like. If the

oxide is so little that no reaction is visible, by the addition of

some tin, the bead appears colorless while hot, and dark brownish-red

and opaque when cold.

_Carbonate of Soda_ dissolves oxide of copper in the oxidation flame

upon platinum wire, to a clear, green bead, which loses its color when

cooling, and becomes opaque.

Upon charcoal, it is reduced to the metal, the soda is absorbed by the

charcoal, and the metallic particles melt with sufficient heat to a

grain.

(_b._) _Silver_ (Ag).--This metal occurs in nature in the metallic

state, and in combination with other metals, particularly with lead.

It also occurs as the sulphide in several mines. It crystallizes in

cubes and octahedrons; is of a pure white color, great lustre, is very

malleable and ductile, and is softer than copper, but harder than

gold. It is not oxidizable, neither at common temperatures nor at

those which are considerably higher. It is soluble in dilute nitric

acid, and in boiling concentrated sulphuric acid.

([chi].) _Protoxide of Silver_ (Ag^{2}O).--It is a black powder. It is

converted by acids and ammonia into oxide and metal.

([beta].) _Oxide of Silver_ (AgO).--It is a greyish-brown or black

powder, and is the base of the silver salts. With aqua ammonia, it is

converted into the black, fulminating silver.

([gamma].) _Superoxide or Binoxide of Silver_ (AgO^{2}).--This oxide

occurs in black needles or octahedral crystals of great metallic

lustre. It is dissolved by the oxygen acids with the disengagement of

oxygen gas.

_Behavior before the Blowpipe._--When exposed to the flames of

oxidation and reduction, the oxides of silver are instantly reduced to

the metallic state.

_Borax_ dissolves silver-oxides upon platinum wire in the oxidation

flame but partially, while the other portion is reduced, the bead

appearing opalescent after cooling, in correspondence to the degree of

saturation. The bead becomes grey in the flame of reduction, the

reduced silver melting to a grain, and the bead is rendered clear and

colorless again.

_Microcosmic Salt_ dissolves oxides of silver in the flame of

oxidation upon platinum wire to a transparent yellowish bead, which

presents, when much of the oxide is present, an opalescent appearance.

In the flame of reduction, the reaction is analogous to that of borax.

By fusion with carbonate of soda in the oxidation and reduction

flames, the silver oxides are instantly reduced to metallic silver,

which fuses into one or more grains.

(_c._) _Gold_ (Au).--This metal occurs mostly in the metallic state,

but frequently mixed with ores, and with other metals. Gold

crystallizes in cubes and octahedrons, is of a beautiful yellow color,

great lustre, and is the most malleable and ductile of all the metals.

It melts at a higher temperature than copper, gives a green colored

light when fused, and contracts greatly when cooling. It does not

oxidize at ordinary temperatures, nor when heated much above them. It

is soluble in nitro-hydrochloric acid (_aqua regia_).

([chi].) _Protoxide of Gold_ (Au^{2}O).--This oxide is a dark violet

colored powder which is converted by a temperature of 540° into

metallic gold and oxygen. It is only soluble in aqua regia. Treated

with hydrochloric acid, it yields the chloride of gold and the metal.

With aqua ammonia, it yields the fulminating gold, which is a blue

mass and very explosive.

([chi].) _Peroxide of Gold_ (Au^{2}O^{3}).--This oxide is an

olive-green or dark brown powder, containing variable quantities of

water. Decomposed at 530°, it yields metallic gold and oxygen.

_Reactions before the Blowpipe._--Oxides of gold are reduced, in both

the oxidation and reduction flames, to the metal, which fuses to

grains.

_Borax_ does not dissolve it, but it is reduced to the metallic state

in this flux in either flame. The reduced metal fuses upon charcoal to

a grain.

_Microcosmic Salt_ presents the same reactions as borax.

When fused with soda, upon charcoal, the soda is absorbed, and the

gold remains as a metallic grain.

TENTH GROUP.--MOLYBDENUM, OSMIUM.

These metals are not volatile, and are infusible before the blowpipe;

but some of their oxides are volatile, and can be reduced to an

infusible metallic powder.

(_a._) _Molybdenum_ (Mo) occurs in the metallic state; also combined

with sulphur, or as molybdic acid combined with lead. It is a white,

brittle metal, and is unaltered by exposure to the air. When heated

until it begins to glow, it is converted into a brown oxide. Heated at

a continued dull red heat, it turns blue. At a higher temperature, it

is oxidized to molybdic acid, when it glimmers and smokes, and is

converted into crystallized molybdic acid upon the surface.

([chi].) _Protoxide of Molybdenum_ (MoO).--This oxide is a black

powder.

([chi].) _Deutoxide of Molybdenum_ (MoO^{2}).--This oxide is a dark

copper-colored crystalline powder.

_Reactions before the Blowpipe._--Metallic molybdenum, its protoxide

and binoxide, are converted in the oxidation flame into molybdic acid.

This acid fuses in the flame of oxidation to a brown liquid, which

spreads, volatilizes, and sublimes upon the charcoal as a yellow

powder, which appears crystalline in the vicinity of the assay. This

sublimate becomes white after cooling. Beyond this sublimate there is

visible a thin and not volatile ore of binoxide, after cooling; this

is of a dark copper-red color, and presenting a metallic lustre.

Heated in a glass tube, closed at one end, it melts to a brown mass,

vaporizes and sublimates to a white powder upon a cool portion of the

tube. Immediately above the assay, yellow crystals are visible; these

crystals are colorless after cooling, and the fused mass becomes light

yellow-colored and crystalline.

Upon platinum foil, in the flame of oxidation, it melts and vaporizes,

and becomes light yellow and crystalline after cooling. In the

reduction flame it becomes blue, and brown-colored if the heat is

increased.

Upon charcoal, in the reduction flame, it is absorbed by the charcoal;

and, with an increase of the temperature, it is reduced to the metal,

which remains as a grey powder after washing off the particles of

charcoal.

_Borax_ dissolves it, in the oxidation flame, upon platinum wire

easily, and in great quantity, to a clear yellow, which becomes

colorless while cooling. By the addition of more of the molybdenic

acid the bead is dark yellow, or red while hot, and opalescent when

cold. In the reduction flame, the color of the bead is changed to

brown and transparent. By the addition of more of the acid, it becomes

opaque.

_Microcosmic Salt_ dissolves it in the oxidation flame, upon platinum

wire, to a clear, yellowish-green bead, which becomes colorless after

cooling. In the reduction flame the bead is very dark and opaque, but

becomes of a bright green after cooling. This is the case likewise

upon charcoal.

_Carbonate of Soda_ dissolves it upon platinum wire in the oxidation

flame with intumescence, to a clear bead, which appears milk-white

after cooling. Upon charcoal the soda and the molybdic acid are

absorbed, the latter is reduced to the metallic state, the metal

remaining as a grey powder after washing off the particles of

charcoal. When molybdic acid, or any other oxide of this metal, is

exposed upon platinum wire, or with platinum tongs, to the point of

the blue flame, a yellowish-green color is communicated to the

external flame. If also any of the compounds of molybdenum are mixed

in the form of a powder with concentrated sulphuric acid and alcohol,

and the latter inflamed, the flame of the alcohol appears colored

green.

(_c._) _Osmium_ (Os).--This metal occurs associated with platinum. It

is of a bluish-grey color, and is very brittle. Ignited in the open

air, it is oxidized to volatile osmic acid, which is possessed of a

pungent smell, and affects the eyes. It communicates a bright white

color to the flame of alcohol. Osmium oxide (OsO^{2}) is converted in

the oxidation flame to osmic acid, which is volatilized with a

peculiar smell, leaving a sublimate.

In the reduction flame it is reduced to a dark-brown infusible

metallic powder. It produces no reactions with fluxes. Carbonate of

soda reduces it upon charcoal to an infusible metallic powder, which

appears, after washing off the particles of charcoal, of a dark-brown

color.

ELEVENTH GROUP.--PLATINUM, PALLADIUM, IRIDIUM, RHODIUM, RUTHENIUM.

These metals are infusible before the blowpipe. They are not volatile,

nor are they oxidizable. Their oxides are, in both flames, reduced to

a metallic and infusible powder. They give no reactions with fluxes,

but are separated in the metallic form. These metals are generally

found associated together in the native platinum, also with traces of

copper, lead, and iron.

The metal palladium is found native, associated with iridium and

platinum. This metal generally occurs in greatest quantity in Brazil.

The metal rhodium is found along with platinum, but in very small

quantities.

Iridium occurs in nature associated with osmium, gold, and platinum,

in the mines of Russia. Its great hardness has rendered it desirable

for the points of gold pens. In South America this metal is found

native, associated with platinum and osmium. The latter metal,

associated with platinum and iridium, has been found in South America.

As these metals will not oxidize or dissolve, they cannot be separated

from each other by the blowpipe with the reagents peculiar to that

species of analysis. It is true that colors may be discerned in the

beads, but these tints proceed from the presence of small traces of

copper, iron, etc.

The ore of osmium and iridium can be decomposed, and the former

recognized by its fetid odor. This metal, strongly ignited in a glass

tube with nitrate of potash, is converted to the oxide of osmium,

which gives an odor not unlike the chloride of sulphur.

As the metals of this group are very rare ones, especially the last

four ones, we shall not devote an especial division to each of them.

For a more detailed statement of their reactions, the student is

referred to the large works upon blowpipe analysis.

CLASS III.

NON-METALLIC SUBSTANCES.

1. _Water_--2. _Nitric Acid_--3. _Carbon_--4. _Phosphorus_

--5. _Sulphur_--6. _Boron_--7. _Silicon_--8. _Chlorine_

--9. _Bromine_--10. _Iodine_--11. _Fluorine_--12. _Cyanogen_

--13. _Selenium_.

(1.) _Water_ (HO).--Pure distilled water is composed of one volume of

oxygen, and two volumes of hydrogen gases; or, by weight, of one part

of hydrogen to eight parts of oxygen gases. Water is never found pure

in nature, but possessing great solvent properties, it always is found

with variable proportions of those substances it is most liable to

meet with, dissolved in it. Thus it derives various designations

depending upon the nature of the substance it may hold in solution, as

lime-water, etc.

In taking cognizance of water in relation to blowpipe analysis, we

regard it only as existing in minerals. The examination for water is

generally performed thus: the substance may be placed in a dry tube,

and then submitted to heat over a spirit-lamp. If the water exists in

the mineral mechanically it will soon be driven off, but if it exists

chemically combined, the heat will fail to drive it off, or if it

does, it will only partially effect it. The water will condense upon

the cool portions of the tube, where it can be readily discerned. If

the water exists chemically combined, a much stronger heat must be

applied in order to separate it.

Many substances may be perhaps mistaken for water by the beginner,

such as the volatile acids, etc.

(2.) _Nitric Acid_ (NO^{5}).--Nitric acid occurs in nature in potash

and soda saltpetre. These salts are generally impure, containing lime,

as the sulphate, carbonate and nitrate, and also iron in small

quantity. The soda saltpetre generally contains a quantity of the

chloride of sodium. The salts containing nitric acid deflagrate when

heated on charcoal. Substances containing nitric acid may be heated in

a glass tube closed at one end, by which the characteristic red fumes

of nitrous acid are eliminated. If the acid be in too minute a

quantity to be thus distinguished, a portion of the substance may be

intimately mixed with some bisulphate of potash, and treated as above.

The sulphuric acid of the bisulphate combines with the base, and

liberates the nitric acid, while the tube contains the nitrous acid

gas.

The nitrate of potassa, when heated in a glass tube, fuses to a clear

glass, but gives off no water. When fused on platinum wire, it

communicates to the external flame the characteristic violet color.

When fused and ignited on charcoal, its surface becomes frothy,

indicating the nitric acid.

(3.) _Carbon_ (C).--Carbon is found in nature in the pure crystallized

state as the diamond. It occurs likewise in several allotropic states

as graphite, plumbago, charcoal, anthracite, etc. It exists in large

quantities combined with oxygen as carbonic acid.

The diamond, although combustible, requires too high a heat for its

combustion to enable us to burn it with the blowpipe. When excluded

from the air, it may be heated to whiteness without undergoing fusion,

but with the free access of air it burns at a temperature of 703° C,

and is converted into carbonic acid. If mixed with nitre, the potassa

retains the carbonic acid, and the carbon may be thus easily

estimated. If a mineral containing carbonic acid is heated, the gas

escapes with effervescence, or a strong mineral acid as the

hydrochloric will expel the acid with the characteristic

effervescence.

(4.) _Phosphorus, Phosphoric Acid _(PO^{6}).--This acid occurs in a

variety of minerals, associated with yttria, copper, uranium, iron,

lead, manganese, etc. Phosphoric acid may be detected in minerals by

pursuing the following process: dip a small piece of the mineral in

sulphuric acid, and place it in the platinum tongs: this is heated at

the point of the blue flame, when the outer flame will become colored

of a greenish-blue hue. This color will not be mistaken for those of

boracic acid, copper, or baryta. Some of the phosphoric minerals, when

heated in the inner flame, will color the outer flame green.

If alumina be present with the phosphoric acid, the following wet

method should be adopted for the detection of the latter: the

substance should be powdered in the agate mortar with a mixture of six

parts of soda, and one and a half parts of silica. The entire mass

should now be placed on charcoal, and melted in the flame of

oxidation. The residue should be treated with boiling water, which

dissolves the phosphate and the excess of carbonate of soda, while the

silicate of alumina, with some of the soda, is left. The clear liquor

is now treated with acetic acid, and heated over the spirit-lamp, and

a small portion of crystallized nitrate of silver added; a

lemon-yellow precipitate of phosphate of silver is quickly developed.

Previous to the addition of the nitrate, the liquor should be well

heated; otherwise, a white precipitate of dipyrophosphate of silver

will be produced.

If the examination be of any of the metallic phosphides, the

substances should be powdered in the agate mortar, and fused with

nitrate of potassa on the platinum wire; the fused mass should be

treated with soda in the same manner as any substance containing

phosphoric acid. The metal and the phosphorus are oxidized, while the

phosphate of potassa is fused, and the metallic oxide separates.

(5.) _Sulphur_ (S).--Sulphur is found native in crystals It is

frequently found associated with lime, iron, silica, carbon, etc., and

combined extensively with metals.

The principal acid of sulphur (the sulphuric, SO^{3}) occurs combined

with the earths, the alkalies, and the metallic oxides. Native sulphur

is recognized, when heated upon charcoal, by its odor (sulphurous

acid) and the blue color of its flame. The compounds of sulphur may be

detected by several methods. If the substance is heated in a glass

tube, closed at one end, the yellow sublimate of sulphur will subside

upon the cool portions of the tube; if the substance should also

contain arsenic, the sublimate will present itself as a light brown

incrustation, consisting of the sulphide of arsenic.

If the assay is heated in the open glass tube, sulphurous acid will

thus be generated; but, if the gas is too little to be detected by the

smell, a strip of moistened litmus paper will indicate the presence of

the acid.

The assay will give off sulphurous fumes if heated in the flame of

oxidation.

If the powdered substance is fused with two parts of soda, and one

part of borax, upon charcoal, the sulphide of sodium is formed. This

salt, if moistened and applied to a polished silver surface, will

blacken it. The borax serves no other purpose than to prevent the

absorption of the formed sulphide of sodium by the charcoal. As

selenium will blacken silver in the manner above indicated, the

presence of this substance should be first ascertained, by heating the

assay; when, if it be present, the characteristic horse-radish odor

will reveal the fact.

Sulphuric acid may be detected by fusing the substance with two parts

of soda, and one part of borax, on charcoal, in the flame of

reduction; the mass must now be wetted with water, and placed in

contact with a surface of bright silver; when, if sulphuric acid be

present, the silver will become blackened.

Or the substance may be fused with silicate of soda in the flame of

reduction. In this case, the soda combines with a portion of the

sulphuric acid, which is then reduced to the sulphide, while the bead

becomes of an orange or red color, depending upon the amount of the

sulphuric acid present. If the assay should, however, be colored, then

the previous treatment should be resorted to.

(6.) _Boron, Boracic Acid_ (BO^{3}).--This acid occurs in nature in

several minerals combined with various bases, such as magnesia, lime,

soda, alumina, etc. Combined with water, this acid exists in nature as

the native boracic acid; this acid gives with test paper prepared from

Brazil wood, when moistened with water, a characteristic reaction, for

the paper becomes completely bleached. An alcohol solution turns

curcuma test paper brown. Heated on charcoal, it fuses to a clear

bead; but, if the sulphate of lime be present, the bead becomes opaque

upon cooling.

The following reaction is a certain one: the substance is pulverized

and mixed with a flux of four and a half parts of bisulphate of

potassa, and one part of pulverized fluoride of calcium. The whole is

made into a paste with water, and the assay is placed on the platinum

wire, and submitted to the point of the blue flame. While the assay is

melting, fluoboric gas is disengaged, which tinges the outer flame

green. If but a small portion of boracic acid is present, the color

will be quite evanescent.

(7.) _Silica, Silicic Acid_ (SiO^{3}).--This acid exists in the

greatest plenty, forming no inconsiderable portion of the solid part

of this earth. It exists nearly pure in crystallized quartz,

chalcedony, cornelian, flint, etc., the coloring ingredients of these

minerals being generally iron or manganese.

With _microcosmic salt_, silica forms a bead in the flame of oxidation

which, while hot, is clear, while the separated silica floats in it. A

platinum wire is generally used for the purpose, the end of it being

first dipped in the salt which is fused into a bead, after which the

silica must be added, and then the bead submitted to the flame of

oxidation.

The silicates dissolve in soda but partially, and then with

effervescence. If the oxygen of the acid be twice that of the base, a

clear bead will be obtained that will retain its transparency when

cold. If the soda be added in small quantity, the bead will then be

opaque. In the first instance, a part of the base which separates is

re-dissolved, and, therefore, the transparency of the glass; but, if

too large a quantity of the soda is added, the separation of the base

is sufficient to render the assay infusible.

(8.) _Chlorine_ (Cl).--Chlorine exists in nature always in

combination, as the chlorides of sodium, potassium, calcium, ammonium,

magnesia, silver, mercury, lead, copper, etc.

The chlorine existing in metallic chlorides may be detected as

follows: the wet way may be accomplished in the following manner. If

the substance is insoluble, it must be melted with soda to render it

soluble; if it be already soluble it must be dissolved in pure water,

and nitrate of silver added, when the one ten-thousandth part of

chlorine will manifest its presence by imparting a milky hue to the

fluid.

By the blowpipe, chlorine may be detected in the following manner:

Oxide of copper is dissolved in microcosmic salt on the platinum wire

in the flame of oxidation, and a clear bead is obtained. The substance

containing the chlorine is now added, and heat is applied. The assay

will soon be enveloped by a blue or purplish flame. As none of the

acids that occur in the mineral kingdom give this reaction, chlorine

cannot be confounded with them, for those which impart a color to the

flame, when mixed with a copper salt, will not do so when tested in

the microcosmic salt bead as above indicated.

If the assay is soluble in water, the following method may be

followed: a small quantity of sulphate of copper or iron is dissolved;

a few drops of the solution is placed upon a bright surface of silver,

and the metallic chloride added; when, if chlorine is present, the

silver is blackened. If the chloride is insoluble in water, it must be

rendered soluble by fusion upon a platinum wire with soda, and then

treated as above.[2]

[2] Plattner.

(9.) _Bromine_ (Br).--The bromide of magnesium and sodium exists in

many salt springs, and it is from these that the bromine of commerce

is obtained. The metallic bromides give the same reactions on silver

with the microcosmic bead and copper salt as the metallic chlorides.

The purplish color which, however, characterizes the chlorides, is

more inclined to greenish with the bromides. If the substance be

placed in a flask or glass tube, and fused with bisulphate of potassa,

over the spirit-lamp, sulphurous gas and bromine will be eliminated.

Bromine will be readily detected by its yellow color and its smell.

Bromine may be readily detected by passing a current of chlorine

through the fluid, after which ether is added and the whole is

agitated. The ether rises to the top, carrying with it the bromine in

solution; after being withdrawn, this ether is mixed with potassa, by

which the bromide and bromate of potassa are formed. The solution is

evaporated to dryness, the residue is fused in a platinum vessel, the

bromate is decomposed, while the bromide remains; this must be

distilled with sulphuric acid and the binoxide of manganese. A red or

brown vapor will then appear, indicating the presence of bromine; this

vapor will color starch paste--which may be put in the receiver on

purpose--of a deep orange color.

If, to a solution containing a bromide, concentrated sulphuric or

nitric acid be added, the bromine is liberated and colors the solution

yellow or red. The hypochlorites act in the same manner. The bromine

salts are coming into use extensively in photography, in consequence

of their greater sensitiveness to the action of light than the

chlorides alone.

(10.) _Iodine_ (I).--This element occurs in salt-springs, generally

combined with sodium; it also exists in rock-salt; it has likewise

been found in sea-water, also in a mineral from Mexico, in combination

with silver, and in one from Silesia, in combination with zinc. As

sea-water contains iodine, we would consequently expect to find it

existing in the sea-weeds, and it is generally from the ashes of these

that it is obtained in commerce.

When the metallic iodides are fused with the microcosmic salt and

copper, as previously indicated, they impart a green color to the

flame. This color cannot be mistaken for the color imparted to the

flame by copper alone. When the metallic iodides are fused in a glass

tube, closed at one end, with the bisulphate of potassa, the vapor of

iodine is liberated, and may be recognized by its characteristic

color. Those mineral waters containing iodine can be treated the same

as for bromine, as previously indicated, while the violet-colored

vapor of the iodine can be easily discerned. The nitrate of silver is

the best test for iodine, the yellow color of the iodide of silver

being not easily mistaken, while its almost insolubility in ammonia

will confirm its identity. The chloride of silver, on the contrary,

dissolves in ammonia with the greatest facility.

The reactions of iodine are similar to those of bromine with

concentrated sulphuric acid and binoxide of manganese, and with nitric

acid: The iodine is released and, if the quantity be not too great,

colors the liquid brown. If there be a considerable quantity of iodine

present, it is precipitated as a dark colored powder. Either of these,

when heated, gives out the violet-color of the iodine.

With starch paste free iodine combines, producing a deep blue

compound. If, however, the iodine be in very minute quantity, the

color, instead of being blue, will be light violet or rose color.

If to a solution of the sulphate of copper, to which a small portion

of sulphurous acid has been added, a liquid containing iodine and

bromine is poured in, a dirty, white precipitate of the subiodide of

copper is produced, and the bromine remains in the solution. The

latter may then be tested for the bromine by strong sulphuric acid.

(11.) _Fluorine_ (Fl).--This element exists combined with sodium,

calcium, lithium, aluminium, magnesium, yttrium, and cerium. Fluorine

also exists in the enamel of the teeth, and in the bones of some

animals. This element has a strong affinity for hydrogen, and,

therefore, we find it frequently in the form of hydrofluoric acid.

Brazil-wood paper is the most delicate test for hydrofluoric acid,

which it tinges of a light yellow color. Phosphoric acid likewise

colors Brazil paper yellow, but as this acid is not volatile at a heat

sufficient to examine hydrofluoric acid, there can be no mistake. If

the substance is supposed to contain this acid, it should be placed on

a slip of glass, and moistened with hydrochloric acid, when the test

paper may be applied, and the characteristic yellow color will

indicate the presence of the fluorine.

As hydrofluoric acid acts upon glass, this property may be used for

its detection. The substance may be put into a glass tube, and

sulphuric acid poured upon it in sufficient quantity to moisten it; a

slight heat applied to the tube will develop the acid, which will act

upon the glass of the tube. If the acid is retained in the mineral by

a feeble affinity, and water be present, a piece of it may be put in

the tube and heated, when the acid gas will be eliminated. The test

paper will indicate its presence, even before it has time to act upon

the glass. If the temperature be too high, fluosilicic acid is

generated, and will form a silicious incrustation upon the cool

portion of the tube.

If the fluorine is too minute to produce either of the above

reactions, then the following process, recommended by Plattner, should

be followed: the assay should be mixed with metaphosphate of soda,

formed by heating the microcosmic salt to dull redness. The mass must

then be placed in an open glass tube, in such a position that there

will be an access of hot air from the flame. Thus aqueous hydrofluoric

acid is formed, which can be recognized by its smell being more

suffocating than chlorine, and also by the etching produced by the

condensation of vapor in the tube. Moist Brazil paper, applied to the

extremity of the tube, will be instantly colored yellow.

Merlet's method for the detection of this acid is the following:[3]

Pulverize the substance for examination, then triturate it to an

impalpable powder, and mix it with an equal part of bisulphate of

potassa. Heat the mass gradually in a moderately wide test-tube. The

judicious application of heat must be strictly observed, for if the

operator first heats the part of the tube where the assay rests, the

whole may be lost on account of the glass being shattered. The

spirit-flame must be first applied to the fore part of the tube, and

then made to recede slowly until it fuses the assay. After the mixture

has been for some time kept in a molten state, the lamp must be

withdrawn, and the part containing the assay severed with a file. The

fore part of the tube must then be well washed, and afterwards dried

with bibulous paper. Should the fluorine contained in the substance be

appreciable, the glass tube, when held up to the light, will be found

to have lost its transparency, and to be very rough to the touch.

[3] Quoted by Plattner.

Great care should be observed not to allow this very corrosive acid to

come into contact with the skin, as an ulcer will be the consequence

that will be extremely difficult to heal.

When hydrofluoric acid comes in contact with any silicious substance,

hydrofluosilicic acid gas is always formed.

(12.) _Selenium_ (Se).--This element occurs in combination with lead

as the selenide, and with copper as the selenide of copper. It exists

also combined with cobalt and lead, as the selenide of these metals;

also as the selenide of lead and mercury.

The smallest trace of selenium may be detected by igniting a small

piece of charcoal in the flame of oxidation, when the peculiar and

unmistakable odor of decayed horse-radish will indicate the presence

of that element. An orange vapor is eliminated if the selenium be

present in any quantity, while there is an incrustation around the

assay of a grey color, with a metallic lustre. This incrustation

frequently presents a reddish-violet color at its exterior edges,

often running into a deep blue. If a substance containing selenium be

placed in a glass tube, closed at one end, and submitted to heat, the

selenium is sublimed, with an orange-colored vapor, and with the

characteristic odor of that substance. Upon the cool portions of the

tube a steel-grey sublimate is deposited, and, beyond that, can be

discerned small crystals of selenic acid. If the mineral be the

seleniferous lead glance, sulphurous acid gas will be given off, and

may be detected by the smell, or by a strip of moistened litmus paper.

If arsenic is present, heating upon charcoal will quickly lead to the

determination of the one from the other.

* * * * *

TABULAR STATEMENT OF THE REACTIONS OF MINERALS BEFORE THE BLOWPIPE.

In PART THIRD of this work, commencing at page 109, the student will

find a sufficiently explicit description of the blowpipe reactions of

those principal substances that would be likely to come beneath his

attention. The following tabular statement of those reactions--which

we take from Scheerer and Blanford's excellent little work upon the

blowpipe--will be of great benefit, as a vehicle for consultation,

when the want of time--or during the hurry of an examination--precludes

the attentive perusal of the more lengthy descriptions in the text.

In the examination of minerals, before the student avails himself of

the aid of the blowpipe, he should not neglect to examine the specimen

rigidly in relation to its physical characters, such as its hardness,

lustre, color, and peculiar crystallization. It is where the

difference of two minerals cannot be distinguished by their physical

appearance, that the aid of the blowpipe comes in most significantly

as an auxiliary. For instance, the two minerals molybdenite and

graphite resemble each other very closely, when examined in regard to

their physical appearance, but the blowpipe will quickly discriminate

them, for if a small piece of the former mineral be placed in the

flame of oxidation, a bright green color will be communicated to the

flame beyond it, while in the latter there will be no color. Thus, in

a very short time, these two minerals can be distinguished from each

other by aid of the blowpipe, while no amount of physical examination

could determine that point. The blowpipe is equally an indispensable

instrument in the determination of certain minerals which may exist in

others as essential or non-essential constituents of them. For

instance, should a minute quantity of manganese be present in a

mineral, it must be fused with twice its bulk of a mixture of two

parts of carbonate of soda, and one part of the nitrate of potassa, in

the flame of oxidation upon platinum foil. The manganate of soda thus

formed will color the fused mass of a bluish-green tint.

Or a slight quantity of arsenic may be discerned by the following

process recommended by Plattner:[4] one grain of the finely pulverized

metal is mixed with six grains of citrate of potassa, and slowly

heated on the platinum spoon. By this means the metals are oxidized,

while the arseniate of potassa is obtained. Then boil the fused mass

in a small quantity of water in a porcelain vessel till all tho

arseniate is dissolved. The metallic oxides are allowed to subside,

and the above solution decanted off into another porcelain vessel. A

few drops of sulphuric acid are added, and the solution boiled to

expel the nitric acid, after which it is evaporated to dryness. In

this operation, the sulphuric acid should be added only in sufficient

quantity to drive off the nitric acid, or, at the utmost, to form a

bisulphate with the excess of potassa. When dry, the salt thus

obtained is pulverized in an agate mortar, and mixed with about three

times its volume of oxalate of potassa, and a little charcoal powder.

The mixture is introduced into a glass bulb having a narrow neck, and

gently warmed over a spirit-lamp in order to drive off the moisture,

which must be absorbed by a piece of blotting-paper in the neck of the

bulb. After a short time, the temperature is increased to a low red

heat, at which the arsenious acid is reduced and the metallic arsenic

sublimed, and which re-condenses in the neck of the bulb. If there

the arsenic be so small in quantity as to exhibit no metallic lustre,

the neck of the bulb may be cut off with a file immediately above the

sublimate, and the latter exposed to the flame of the blowpipe, when

the arsenic is volatilized, and may be recognized by its garlic odor.

[4] Quoted by Scheerer.

If the presence of cadmium is suspected in zinc-blende, it may be

detected by fusing a small piece of the blende upon charcoal in

carbonate of soda. The peculiar bright yellow sublimate of the oxide

of cadmium, if it be present, will not fail to indicate it. This

incrustation can be easily distinguished from that of zinc. Thus, with

the three illustrations we have given, the student will readily

comprehend the great utility of the blowpipe in the examination of

minerals.

Although the following tables were not arranged especially for the

last part of this work, still this arrangement is so good that by

their consultation the student will readily comprehend at a glance

what requires some detail to explain, and we feel no hesitation in

saying that, although they are not very copious, they will not fail to

impart a vast amount of information, if consulted with any degree of

carefulness.

The minerals given are such as are best known to English and American

mineralogists under the names specified. For more detailed reactions

than could be crowded into a table, the student will have to consult

the particular substance as treated in Part Third. If this part is

perused carefully previous to consulting the tables, these will be

found eminently serviceable as a refresher of the memory, and may thus

save much time and trouble.

And, finally, we would certainly recommend the student, after he shall

have gone through our little volume (if he is ambitious of making

himself a thorough blowpipe analyst), to then take up the larger works

of Berzelius and Plattner, for our treatise pretends to nothing more

than a humble introduction to these more copious and scientific works.

* * * * *

Mineral. Diamond

Formula. C

Behavior

in glass-bulb. --

on platinum foil. In fine powder is slowly consumed without

residue in a strong oxidizing Flame.

* * * * *

Mineral. Graphite

Formula. C with some iron silica, etc.

Behavior

in glass-bulb. Generally gives off water.

on platinum foil. Is slowly consumed leaving more or less ash,

principally Fe^{2}O^{3}.

* * * * *

Mineral. Anthracite

Formula. C + x[.H]

Behavior

in glass-bulb. Evolves water.

on platinum foil. Is slowly consumed with the exception of a small

quantity of ash.

* * * * *

Mineral. Wallsend-coal

Formula. C, H, O, S and ash.

Behavior

in glass-bulb. Intumesces and gives off water and tarry matters

which partly condense in bulb, and leave a

porous coke.

on platinum foil. Takes fire under blowpipe flame, and burns with

a smoky flame, depositing much soot and leaving

a porous cinder which burns slowly and leaves a

small ash.

* * * * *

Mineral. Cannel-coal

Formula. C, H, N, O, S and ash.

Behavior

in glass-bulb. As the preceding but gives off more tar.

on platinum foil. Similar to the preceding. If held to the

lamp-flame, takes fire and burns for some

seconds.

* * * * *

Mineral. Brown-coal

Formula. C, H, N, O, S, and ash.

Behavior

in glass-bulb. Gives off much water and tar, and leaves a

porous cinder retaining the form of the original

fragment.

on platinum foil. Burns slowly and without flame, leaving some

ash.

* * * * *

Mineral. Asphaltum

Formula. C + H + O.

Behavior

in glass-bulb. Fuses with ease affording an empyreumatic oil

having an alkaline reaction, and combustible

gasses, and leaves a carbonaceous residue,

which is entirely consumed under the blowpipe

flame, except a little ash.

on platinum foil. Takes fire and burns with a bright flame and a

thick smoke.

* * * * *

Mineral. Elaterite

Formula. C + H.

Behavior

in glass-bulb. Fuses and gives off water having an acid

reaction, naphtha and a tarry fluid, which

chiefly condense in the neck of the bulb, and

leave a light, pulverulent carbonaceous residue.

on platinum foil. Fuses, takes fire, and burns with a smoky flame,

leaving a carbonaceous residue, which under the

blowpipe flame, is quickly consumed, with the

exception of the ashes.

* * * * *

Mineral. Hachettine

Formula. C + H.

Behavior

in glass-bulb. Fuses to a clear colorless liquid, which

solidifies on cooling and has a tallow-like

smell.

on platinum foil. Fuses, takes fire, and burns with a bright flame

until entirely consumed.

* * * * *

Mineral. Ozokerite

Formula. C + H.

Behavior

in glass-bulb. Fuses readily to a clear brown oily fluid, which

solidifies on cooling.

on platinum foil. As the preceding.

* * * * *

Mineral. Amber

Formula. C + H + O.

Behavior

in glass-bulb. Fuses with difficulty, and affords water, an

empyreumatic oil, and succinic acid which

condense in the neck of the bulb leaving a

shining black residue.

on platinum foil. Takes fire and burns with a yellow flame and a

peculiar aromatic odor.

* * * * *

Mineral. Mellite

Formula. [...Al][=M]^{3} + 15[.H]

Behavior

in glass-bulb. Gives off water. If heated to redness, is

carbonized, and gives a slight empyreumatic odor.

on platinum foil. On charcoal burns to a white ash, which moistened

with nitrate of cobalt and heated shows the

alumina reaction.

* * * * *

POTASH.

* * * * *

Mineral. Nitre

Formula. [.K][.....N]

Behavior

(1) in glass-bulb. Fuses readily to a clear liquid and with a

strong heat boils with the evolution of oxygen.

(2) in open tube. --

(3) on charcoal. Deflagrates leaving a saline mass, which is

absorbed into charcoal and gives a sulphur

reaction on silver.

(4) in forceps. On platinum wire fuses and colors the flame

violet more or less modified by lime and soda.

(5) in borax. --

(6) in mic. salt. --

(7) with carb. soda. --

(8) Special reactions. With bisulphate of potassa in the glass-bulb

evolves nitrous fumes.

* * * * *

Mineral. Polyhalite

Formula. [.K][...S]+[.Mg][...S]+2[.Ca][...S]+2[.H]

Behavior

(1) in glass-bulb. Gives off water.

(2) in open tube. --

(3) on charcoal. Fuses to a reddish bead, which in the reducing

flame solidifies and shrinks to a hollow crust.

(4) in forceps. On platinum wire fuses and colors the flame

yellow from a small quantity of soda.

(5) in borax. Dissolves with ebullition to a clear glass,

which is slightly colored by iron, and when

saturated become opaque on cooling.

(6) in mic. salt. As in borax.

(7) with carb. soda. Fuses. The alkalies are absorbed by the charcoal

leaving the lime and magnesia infusible on the

surface.

(8) Special reactions. The alkaline mass when laid on silver gives a

sulphur reaction.

* * * * *

SODA.

* * * * *

Mineral. Rock-salt

Formula. NaCl.

Behavior

(1) in glass-bulb. Fuses to a clear liquid

(2) in open tube. --

(3) on charcoal. Fuses, is absorbed by the charcoal and partially

volatilized incrusting the charcoal around.

(4) in forceps. Fuses with great ease and colors the flame

yellow.

(5) in borax. --

(6) in mic. salt. --

(7) with carb. soda. --

(8) Special reactions. Gives the chlorine reactions.

* * * * *

Mineral. Natron

Formula. [.Na][..C] + 10[.H]

Behavior

(1) in glass-bulb. Fuses, with the evolution of water.

(2) in open tube. --

(3) on charcoal. Fuses, and is absorbed into the pores of the

charcoal.

(4) in forceps. Fuses and behaves as the preceding.

(5) in borax. --

(6) in mic. salt. --

(7) with carb. soda. --

(8) Special reactions. Dissolves in acid with violent effervescence.

* * * * *

Mineral. Soda-nitre

Formula. [.Na][.....N].

Behavior

(1) in glass-bulb. Fuses and if strongly heated evolves nitrous

fumes.

(2) in open tube.

--

(3) on charcoal.

Deflagrates and is absorbed into the charcoal.

(4) in forceps. Deflagrates on platinum wire, coloring the flame

yellow.

(5) in borax. --

(6) in mic. salt. --

(7) with carb. soda. --

(8) Special reactions. In a glass-bulb with bisulphate of potassa,

gives the NO^{5}-reaction.

* * * * *

Mineral. Glauber-salt

Formula. [.Na][...S] + 10[.H].

Behavior

(1) in glass-bulb. Fuses and gives off water having a neutral

reaction.

(2) in open tube. --

(3) on charcoal. Fuses, and is absorbed by the charcoal. The

saturated charcoal laid upon silver gives the

sulphur reaction

(4) in forceps. Fuses and colors the flame yellow.

(5) in borax. --

(6) in mic. salt. --

(7) with carb. soda. --

(8) Special reactions. Gives the SO^{3}-reaction.

* * * * *

Mineral. Glauberite

Formula. [.Na][...S] + [.Ca][...S].

Behavior

(1) in glass-bulb. Decrepitates with the evolution of more or less

water, and when strongly heated fuses to a clear

liquid.

(2) in open tube. --

(3) on charcoal. Fuses to a clear bead, then spreads out; the

soda is absorbed and the lime left on the

surface. Laid on silver, the fused mass gives a

sulphur reaction.

(4) in forceps. Fuses easily to a clear glass, coloring the

flame yellow.

(5) in borax. Fuses easily and gives the lime reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. As alone in charcoal.

(8) Special reactions. As in preceding.

* * * * *

Mineral. Borax

Formula. [.Na][...B]^{2}+10[.H].

Behavior

(1) in glass-bulb. Intumesces with the evolution of water, and

under a strong heat fuses.

(2) in open tube. --

(3) on charcoal. Intumesces and fuses to a clear bead more or

less colored by impurities.

(4) in forceps. As on charcoal.

(5) in borax. --

(6) in mic. salt. --

(7) with carb. soda. Fuses to a clear bead, which becomes crystalline

on cooling.

(8) Special reactions. Gives the boracic-acid-reaction.

* * * * *

Mineral. Cryolite

Formula. 3NaFl+Al^{2}Fl^{3}.

Behavior

(1) in glass-bulb. Decrepitates slightly and gives a trace of

water.

(2) in open tube. If heated so that the flame be allowed to play

up the tube upon the mineral, flourine is

evolved, which corrodes the interior of the

tube.

(3) on charcoal. Fuses to a limpid bead, which on cooling becomes

a white enamel. If heated for some time, it

bubbles, gives off fluorine and becomes

infusible.

(4) in forceps. Fuses, coloring the flame yellow.

(5) in borax. Dissolves to a clear bead, which is rendered

opaque by a large addition.

(6) in mic. salt. As in borax.

(7) with carb. soda. Fuses to a clear bead, then spreads out on the

charcoal, the soda is absorbed, and an infusible

mass of alumina remains.

(8) Special reactions. If the alumina residue obtained be moistened

with cobalt solution and heated strongly, it

assumes a beautiful blue color.

* * * * *

BARYTA AND STRONTIA.

* * * * *

Mineral. Heavy-spar

Formula. [.Ba][...S].

Behavior

(1) in glass-bulb. Sometimes decrepitates and gives off more or

less water

(2) in open tube. --

(3) on charcoal. Fuses in the reducing flame.

(4) in forceps. Fuses with difficulty on edges. Colors the outer

flame green. In reducing flame forms BaS, which

fuses readily.

(5) in borax. Gives the baryta-reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Fuses to a clear bead; then spreads out and is

absorbed into the charcoal. The fused mass laid

on silver gives the S-reaction.

(8) Special reactions. If fused with potassa on platinum, gives the

SO^{3}-reaction.

* * * * *

Mineral. Celestine

Formula. [.Sr][...S].

Behavior

(1) in glass-bulb. --

(2) in open tube. --

(3) on charcoal. Fuses to a milk-white bead.

(4) in forceps. Colors the flame crimson.

(5) in borax. Gives the strontia-reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Similar to the preceding.

(8) Special reactions. Similar to the preceding.

* * * * *

Mineral. Witherite

Formula. [.Ba][..C].

Behavior

(1) in glass-bulb. Decrepitates more or less and evolves Water.

(2) in open tube. --

(3) on charcoal. Fuses, effervesces, and is partially absorbed by

the charcoal.

(4) in forceps. Colors the outer flame intensely green.

(5) in borax. Dissolves with effervescence and gives the

baryta-reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Fuses to a clear bead; then spreads out and

passes into the charcoal.

(8) Special reactions. In dilute HCl dissolves with much effervescence.

* * * * *

Mineral. Strontianite

Formula. [.Sr][..C].

Behavior

(1) in glass-bulb. Becomes opaque.

(2) in open tube. --

(3) on charcoal. As in the forceps.

(4) in forceps. Exfoliates and becomes arborescent. The

filaments glow brilliantly and fuse on the

point. Colors the flame brilliantly crimson.

(5) in borax. Resembles the preceding.

(6) in mic. salt. As in borax.

(7) with carb. soda. As the preceding.

(8) Special reactions. As the preceding.

* * * * *

Mineral. Barytocalcite.

Formula. [.Ba][..C] + [.Ca][..C].

Behavior

(1) in glass-bulb. As in the preceding.

(2) in open tube. --

(3) on charcoal. In powder frits together, but does not fuse.

(4) in forceps. Colors the flame green in the centre and red

towards the point.

(5) in borax. Dissolves with effervescence. In large

quantities gives a semi-crystalline bead.

(6) in mic. salt. As in borax, but the saturated bead is

milk-white.

(7) with carb. soda. Fuses, and is partially absorbed leaving the

lime on the surface.

(8) Special reactions. As witherite.

* * * * *

LIME.

* * * * *

Mineral. Gypsum

Formula. [.Ca][...S] + 2[.H].

Behavior

(1) in glass-bulb. Turns white, giving off water and being

converted into plaster of Paris.

(2) in open tube. --

(3) on charcoal. In the reducing flame forms CaS, which has an

alkaline reaction on test paper, and gives a

sulphur-reaction when laid on silver and

moistened.

(4) in forceps. Fuses with difficulty to a bead, coloring the

flame red.

(5) in borax. Dissolves to a clear bead, which gives the lime-

reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Behaves as lime. The alkaline mass laid on

silver and moistened gives the sulphur-reaction.

(8) Special reactions. Gives the sulphuric-acid reaction.

* * * * *

Mineral. Apatite

{ Cl

Formula. [.Ca]{ -- +3[.Ca]^{3}[.....P]

{ Fl

Behavior

(1) in glass-bulb. Occasionally decrepitates and gives off some

water.

(2) in open tube. --

(3) on charcoal. --

(4) in forceps. IV. Previously dipped in SO^{3} colors the flame

green, afterwards red.

(5) in borax. Dissolves easily and when in some quantity gives

an opaline bead.

(6) in mic. salt. Gives the lime-reaction.

(7) with carb. soda. Is infusible. The alkali is absorbed, leaving

the lime on the on the surface of the charcoal.

(8) Special reactions. With microcosmic salt and oxide of copper, gives

the chlorine-reaction. With microcosmic salt in

the open tube evolves fluorine.

* * * * *

Mineral. Pharmacolite

Formula. [.Ca]^{2}[.....As] + 6[.H].

Behavior

(1) in glass-bulb. Gives off water, and emits an arsenical odor.

(2) in open tube. --

(3) on charcoal. Fuses to an opaque bead and emits a strong smell

of arsenic.

(4) in forceps. Fuses to a translucent violet colored bead, the

color being due to cobalt. Colors the flame blue

at first, then faintly red.

(5) in borax. Dissolves readily to a bead strongly colored by

cobalt, which obscures the lime-reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Fuses, and emits As. The alkali is then absorbed

by the charcoal, as in the preceding.

(8) Special reactions. --

* * * * *

Mineral. Calespar

Formula. [.Ca][..C].

Behavior

(1) in glass-bulb. Turns white and sometimes decrepitates. Strongly

heated loses CO^{2} and becomes caustic.

(2) in open tube. --

(3) on charcoal. Turns white, or brown if containing much iron or

manganese and glows brilliantly.

(4) in forceps. Glows brilliantly, coloring the flame red.

Becomes caustic and shows a strong alkaline

reaction.

(5) in borax. Dissolves with evolution of CO^{2} and when pure

gives the lime-reaction. The bead is generally

more or less colored by iron and manganese.

(6) in mic. salt. As in borax.

(7) with carb. soda. Fuses, and behaves as other lime-salts.

(8) Special reactions. Dissolves with effervescence in cold HCl.

* * * * *

Mineral. Fluorspar

Formula. CaFl

Behavior

(1) in glass-bulb. Phosphoresces with various colors, when heated

in the dark.

(2) in open tube. --

(3) on charcoal. Fuses easily to a clear bead, which becomes opaque

on cooling, then loses fluorine, glows brilliantly

and becomes infusible.

(4) in forceps. As on charcoal. Colors the flame red.

(5) in borax. Gives the lime-reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Fuses to a clear bead, opaque on cooling. With

an addition of the alkali behaves as lime.

(8) Special reactions. With microcosmic salt in open tube gives the

fluorine-reaction.

* * * * *

MAGNESIA.

* * * * *

Mineral. Brucite

Formula. [.Mg][.H].

Behavior

(1) in glass-bulb. Evolves water.

(2) in open tube. --

(3) on charcoal. --

(4) in forceps. V.

(5) in borax. Behaves as magnesia. Sometimes gives a faint

iron-reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Behaves as magnesia.

(8) Special reactions. With nitrate of cobalt, gives the magnesia

reaction

* * * * *

Mineral. Epsomite

Formula. [.Mg][...S] + 7[.H].

Behavior

(1) in glass-bulb. Evolves water having an acid reaction on test

paper.

(2) in open tube. --

(3) on charcoal. Gives of HO and SO^{3}, shines brilliantly, and

becomes alkaline and caustic.

(4) in forceps. V. As on charcoal.

(5) in borax. Behaves as magnesia.

(6) in mic. salt. As in borax.

(7) with carb. soda. The alkali is absorbed leaving the magnesia

on surface of the charcoal. Gives the

sulphur-reaction on silver.

(8) Special reactions. The magnesian residue obtained on treating with

carbonate of soda (7), assumes a flesh-tint,

when treated with cobalt.

* * * * *

Mineral. Boracite

Formula. [.Mg][...B]^{2} + 2[.Mg][...B].

Behavior

(1) in glass-bulb. Occasionally gives off a trace of water.

(2) in open tube. --

(3) on charcoal. Fuses with intumescence to a white crystalline

bead.

(4) in forceps. I. As on charcoal. Colors the flame green.

(5) in borax. Fuses easily to a clear bead, which is

crystalline, when containing much of the

mineral, and is usually slightly tinted by

iron.

(6) in mic. salt. As in borax.

(7) with carb. soda. With a small quantity of alkali fuses to a clear

bead on cooling. With a larger quantity gives a

clear, uncrystallizable bead.

(8) Special reactions. --

* * * * *

Mineral. Magnesite

Formula. [.Mg][..C].

Behavior

(1) in glass-bulb. Sometimes gives off a small quantity of water.

(2) in open tube. --

(3) on charcoal. Is infusible. With cobalt-solution, assumes a

dusky flesh tint.

(4) in forceps. --

(5) in borax. Behaves as magnesia. Sometimes a slight

iron-reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Fuses to a bead, the soda is then absorbed,

leaving an infusable mass of magnesia.

(8) Special reactions. The magnesian residue obtained by fusing with

carbonate of soda gives the magnesian-reaction

with nitrate of cobalt. Dissolves with

effervescence in warm HCl.

* * * * *

Mineral. Mesitine spar

Formula. ([.Mg][.Fe][.Mn])[..C].

Behavior

(1) in glass-bulb. As magnesite.

(2) in open tube. --

(3) on charcoal. Is infusible. Assumes a deep brown color.

(4) in forceps. V.

(5) in borax. Gives the iron and manganese-reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. As magnesite, but the residual mass has a dark

color from iron and manganese.

(8) Special reactions. Dissolves with effervescense in warm HCl. With

carbonate of soda and nitre gives a

manganese-reaction.

* * * * *

ALUMINA.

* * * * *

Mineral. Sapphire

Corundum

Emery

Formula. [...Al=].

Behavior

(1) in glass-bulb. --

(2) in open tube. --

(3) on charcoal. --

(4) in forceps. V.

(5) in borax. In fine powder dissolves slowly to a colorless

glass.

(6) in mic. salt. As in borax.

(7) with carb. soda. --

(8) Special reactions. In fine powder moistened with cobalt-solution

and heated yields a blue color.

* * * * *

Mineral. Websterite

Formula. [...Al][...S] + 9[.H].

Behavior

(1) in glass-bulb. Gives off water, and, when heated to incipient

redness, sulphurous acid.

(2) in open tube. --

(3) on charcoal. Gives off water and SO^{3}, leaving an infusible

mass.

(4) in forceps. V.

(5) in borax. Behaves as alumina.

(6) in mic. salt. As in borax.

(7) with carb. soda. Yields an infusible mass, which laid on silver

and moistened, produces a black stain.

(8) Special reactions. Fused with potassa in platinum has no action on

silver. Cobalt-solution produces the alumina

reaction.

* * * * *

Mineral. Native Alum

Formula. [.R][...S] + [...Al][...S]^{3} + 24[.H].

Behavior

(1) in glass-bulb. Intumesces greatly and gives off much water.

Strongly heated, evolves SO^{3}, which reddens

litmus.

(2) in open tube. --

(3) on charcoal. Intumesces and become infusible.

(4) in forceps. V. Colors the flame violet if a potassa

alum--yellow if soda--be present.

(5) in borax. Dissolves and gives the iron and manganese

reaction, if these oxides be present. Otherwise

the bead is colorless.

(6) in mic. salt. As in borax.

(7) with carb. soda. The alkali is absorbed into the charcoal,

leaving an infusable mass which gives the sulfur

reaction on silver.

(8) Special reactions. If not containing too much iron or manganese

gives an alumina reaction with nitrate of of

cobalt. In other respects as the preceding.

* * * * *

Mineral. Turquoise

Formula. [...Al=]^{2}[.....P] + 5[.H].

Behavior

(1) in glass-bulb. Evolves water, occasionally decrepitates and

turns black.

(2) in open tube. --

(3) on charcoal. Turns brown, but remains infusible.

(4) in forceps. V. As on charcoal. Colors the outer flame green.

(5) in borax. In the oxidizing flame, gives a green bead, due

to copper and iron. In reducing flame, opaque red.

(6) in mic. salt. As in borax.

(7) with carb. soda. Intumesces, then fuses to a semi-clear glass

colored by iron. With more alkali yields an

infusible mass.

(8) Special reactions. Gives the phosphoric-acid reaction.

* * * * *

Mineral. Wavellite

Formula. [Al=]F^{3} + 3([...Al=]^{4}[.....P]^{3} + 18[.H].)

Behavior

(1) in glass-bulb. Evolves water and some fluorine, which attacks

the glass.

(2) in open tube. --

(3) on charcoal. Exfoliates and turns white.

(4) in forceps. V. As on charcoal. Colors the outer flame green,

especially if moistened with SO^{3}.

(5) in borax. As alumina. Generally gives also a slight iron

reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Forms an infusible white mass.

(8) Special reactions. With cobalt-solution on charcoal gives the

alumina reaction.

* * * * *

Mineral. Spinel

Formula. [.R][...Al=].

Behavior

(1) in glass-bulb. --

(2) in open tube. --

(3) on charcoal. --

(4) in forceps. V.

(5) in borax. Gives a slight iron reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Fuses partially and forms a porous mass.

(8) Special reactions. With nitrate of cobalt gives the alumina

reaction. With nitre and carbonate of soda a

slight manganese reaction.

* * * * *

SILICATES.

The presence of silica in a mineral can easily be ascertained by

treating a small fragment in a bead of microcosmic salt. The bases

will dissolve out with more or less difficulty in the salt, and the

silica being insoluble will remain suspended in the bead, retaining

the original form of the fragment. In borax, the silicates of lime and

magnesia generally dissolve with considerable ease, but those of

alumina slowly and with difficulty. The silicates of lime are moreover

frequently characterized by intumescence or ebullition, when heated in

the forceps in the blowpipe flame. The minerals presenting this

character are marked in the table. As the most convenient mode of

classifying the silicates for blowpipe examination, the following

arrangement will be adopted:

TABLE I.--ANHYDROUS SILICATES.

TABLE II.--HYDROUS SILICATES.

FUSIBILITY.

I. Readily fusible to a bead.

II. With difficulty fusible to a bead.

III. Readily fusible on the edges.

IV. With difficulty fusible on the edges.

V. Infusible.

a. Afford a fluid bead with carbonate of soda.

b. Afford a fluid bead with but little of that salt, but with a

larger quantity a slaggy mass.

c. Afford a slaggy mass only.

This classification of minerals, according to their fusibility and

their behavior with carbonate of soda, was originally proposed by

_Berzelius_, and a table of the principal oxidized minerals arranged

according to these characters is given in his handbook of the

blowpipe, and thence adopted, with some alterations by _Plattner_, in

the very excellent and detailed work already many times cited. In the

following general table I., the more important silicates only are

included, and in table II. are enumerated in alphabetical order those

which afford characteristic reactions.

TABLE I.

Anhydrous Silicates.

________________________________________________________________________

Fus. alone and with NaC.

Mineral. Formula.

________________________________________________________________________

I.

a. Axinite ([.Ca][.Mg])^{3}([...B][...Si])^{3} +

([...Al=][...Fe=][...Mn=])^{2}([...Si][...B]) Int.

Elaolite ([.K][.Na])^{3}[...Si] + 3[...Al=][...Si] Int.

Garnet [.R]^{3}[...Si] + [.R=][...Si]

Oligoclase [.Na][...Si] + [...Al=][...Si]^{2}

Scapolite ([.Ca][.Na])^{3}[...Si]^{2} + 2[...Al=][...Si] Int.

Spodumene ([.Li][.Na])^{3}[...Si]^{2} + 4[...Al=][...Si]^{2}Int.

b. Asbestos As Hornblende

to II.

Augite ([.Ca][.Mg][.Fe][.Mn])^{3}[...Si]^{2} Int.

some var.

Epidote ([.Ca]Fe)^{3}[...Si] + Int.

to III. 2([...Al][...Fe][...Mn])[...Si]

Hornblende ([.Ca][.Mg][.Fe])^{4} + ([...Si][...Al=])^{3} Int.

some var.

Sodalite [.Na]^{3}[...Si] + 3[...Al=][...Si] + NaCl Int.

to III.

Vesuvian 3([.Ca][.Mg])^{3}[...Si] +

2([...Al=][...Fe=])[...Si] Int.

c. Biaxial Mica [.K][...Si] + 4([...Al=][...Fe=])[...Si]

to III.

Hauyne ([.K][.Na])^{3}[...Si] + 3[...Al=][...Si] +

[.Na][...Si]

Tourmaline ([.R][...R=][...B])^{4}[...Si]^{3} Int.

to V.

II.

a. Labradorite ([.Ca][.Na][.K])[...Si] +

([...Al=][...Fe=])[...Si]

Lepidolite (KNaL)F + ([...Al=][...Fe=])[...Si]^{2}?

Ryacolite [.K][...Si] + [...Al=][...Si]^{2}

Albite [.Na][...Si] + [...Al=][...Si]^{3}

b. Augite [.R]^{3}[...Si]^{2}

some var.

Actinolite ([.Ca][.Mg][.Fe])^{4}[...Si]^{3} Int.

Diopside ([.Ca][.Mg])^{3}[...Si]^{2} |

Humboltilite 2([.Ca][.Mg][.Na][.K])[...Si] +

([...Al=][...Fe=])[...Si]

Sahlite As Augite

Tremolite ([.Ca][.Mg])^{4}[...Si]^{3}

c. Pyrope ([.Ca][.Mg][.Fe])^{3}[...Si] + Al[...Si] +

m[...Cr]?

III.

a. Anorthite ([.Ca][.Mg][.Na][.K])^{3}[...Si] +

3([...Al=][...Fe=])[...Si]

Nepheline ([.Na][.K][.Ca])^{2}[...Si] + 2[...Al=][...Si]

Obsidian [...Si],[...Al=],[...Fe=],[.Fe],[.Ca][.Na][.K] Int.

Orthoclase ([.K][.Na])[...Si] + [...Al=][...Si]^{3}

Petalite ([.Li][.Na])^{3}[...Si]^{4} + 4[...Al=][...Si]^{4}

Pumice [...Si],[...Al=],[.Ca],[.K],[.Na],[.H] Int.

b. Gadolinite ([.Y][.Ce][.La][.Fe][.Ca])^{3}[...Si]

to V.

Nephrite ([.Ca][.Mg][.Fe])^{4}[...Si]^{3}? Int.

Wollastonite [.Ca]^{3}[...Si]^{2} |

c. Iolite ([.Mg][.Fe])^{3}[...Si]^{2} + 3[...Al=][...Si]

IV.

a. Beryl [...Be][...Si]^{2} + [...Al=][...Si]^{2}

b. Diallage ([.Ca][.Mg][.Fe])^{3}([...Si][...Al=])^{2}

Hypersthene ([.Mg][.Fe])^{3}[...Si]^{2} |

c. Fuchsite ([.K]^{5}[...Si])^{2} +

9([...Al=][...Cr=])^{6}[...Si]^{6}

V.

a. Leucite [.K]^{3}[...Si]^{2} + [...Al=][...Si]^{2}

b. Chondrodite ([.Mg],[.Mg]F)^{4}([...Si]SiF^{3})

Olivine ([.Mg][.Fe][.Ca])^{2}[...Si]

c. Andalusite ([...Al=]Fe)^{3}[...Si]^{2}

Chrysoberyl [...Be] + [...Al=]

Kaynite [...Al=]^{3}[...Si]^{2}

Pycnite 6[...Al=]^{3}[...Si]^{2} + (3[...Al=]F^{3} +

2[...Si]F^{3})

Topaz 6[...Al=]^{3}[...Si]^{2} + (3[...Al=]F^{3} +

2[...Si]F^{3})

Zircon [...Zr=][...Si]

Staurolite ([...Al=]Fe)^{2}[...Si]

________________________________________________________________________

Hydrous Silicates.

________________________________________________________________________

Fus. alone and with NaC.

Mineral. Formula.

________________________________________________________________________

I.

a. Analcime [.Na]^{3}[...Si]^{2} + 3[...Al=][...Si]^{2}

+ 6[.H] Int.

Apophyllite ([.K], KF)([...Si], SiF^{3}) + 6[.Ca][...Si] +

15[.H] Int.

Brewsterite ([.Sr][.Ba])[...Si] + [...Al=][...Si]^{3} + 5[.H] Int.

Chabasite ([.Ca],[.Na],[.K])^{3}[...Si] +

3[...Al=][...Si]^{2} + 18[.H] Int.

Lapis Lazuli [...Si],[...S],[...Al=], Fe, [.Ca], [.Na], [.H]

Laumonite [.Ca]^{3}[...Si]^{2} + 3[...Al=][...Si]^{2}

+ 12[.H] Int.

Mesotype ([.Na][.Ca])[...Si] + [...Al=][...Si] + 3[.H] Int.

Natrolite [.Na][...Si] + [...Al=][...Si] + 2[.H] Int.

Prehnite [.Ca]^{2}[...Si] + [...Al=][...Si] + [.H] Int.

Scolezite [.Ca][...Si] + [...Al=][...Si] + 3[.H] Int.

Thomsonite ([.Ca][.Na])^{3}[...Si] + 3[...Al=][...Si]

+ 7[.H] Int.

Datholite 2[.Ca]^{3}[...Si] + [...B]^{3}[...Si]^{2} + 3[.H] Int.

Heulandite [.Ca][...Si] + [...Al=][...Si]^{3} + 5[.H] Int.

Stilbite [.Ca][...Si] + [...Al=][...Si]^{3} + 6[.H] Int.

b. Okenite [.Ca]^{3}[...Si]^{4} + 6[.H] Int.

Pectolite ([.Ca][.Na])^{4}[...Si]^{3} + [.H] Int.

c. Saponite 2[.Mg]^{3}[...Si]^{2} + [...Al=][...Si]

+ 10 or 6[.H]

II.

a. Antrimolite 3([.Ca][.K])[...Si] + 5[...Al=][...Si] +

15[.H]

Harmatome [...Ba][...Si] + [...Al=]S^{2} + 5[.H]

b. Brevicite [.Na][...Si] + [...Al=][...Si] + 2[.H]

Orthite [.R]^{3}[...Si] + [...R=][...Si] + ([.H]?) Int.

III.

c. Pitchstone [...Si],[...Al=], Fe, [.Mg][.Na], [.K][.H]

Talc to V. [.Mg]^{6}[...Si]^{5} + 2[.H]

Chlorite 3([.Mg]Fe)^{3}[...Si] + ([...Al=]Fe)^{2}[...Si]

+ 9[.H]

Pinite [...Si],[...Al=],[.Fe],[.K],[.Mg],[.H]

IV.

a. Steatite [.Mg]^{6}[...Si]^{5} + 4[.H]

c. Gilbertite [...Si],[...Al=],[.Fe],[.Mg],[.H] Int.

Meerschaum [.Mg][...Si] + [.H] |

Serpentine [.Mg]^{9}[...Si]^{4} + 6[.H] |

V.

a. Gismondine ([.Ca][.K])^{2}[...Si] + 2[...Al=][...Si] + 9[.H]

________________________________________________________________________

TABLE II.

_______________________________________________________________________

|

Analcime | If transparent becomes white and opaque when heated,

| but on incipient fusion resumes its transparency and

| then fuses to a clear glass.

|

Andalusite | When powdered and treated with cobalt solution on

| charcoal, assumes a blue color.

|

Apophyllite | Fuses to a frothy white glass.

|

Axinite | Imparts a green color to the blowpipe flame, owing to

| the presence of boracic acid. This reaction is

| especially distinct, if the mineral be previously mixed

| with fluorspar and bisulphate of potassa.

|

Beryl | Sometimes gives a chromium reaction in borax and

| microcosmic salt.

|

Chabasite | Fuses to a white enamel.

|

Chondrodite | Evolves fluorine in the glass tube, both when heated

| alone and with microcosmic salt. It sometimes also

| gives off a trace of water.

|

Chrysoberyl | Is unattacked by carbonate of soda. With nitrate of

| cobalt on charcoal the finely powdered mineral

| assumes a blue color.

|

Datholite | Fuses to a clear glass and colors the flame green.

|

Diallage | Frequently gives off water in small quantity.

|

Fuchsite | Gives the chromium reaction with borax and microcosmic

| salt.

|

Gadolinite | That from Hitteroe, if heated in a partially covered

| platinum spoon to low redness, glows suddenly and

| brilliantly.

|

Hauyne | Affords the sulphur reaction both on charcoal and when

| fused with potassa. It contains both sulphur and

| sulphuric acid.

|

Hypersthene | As Diallage.

|

Kyanite | As Andalusite.

|

Lapis Lazuli | Fuses to a white glass, and when treated with carbonate

| of soda on charcoal, gives the sulphur reaction on

| silver.

|

Laumonite | When strongly heated, exfoliates and curls up.

|

Lepidolite | Colors the blowpipe flame crimson, from lithia; also

| gives the fluorine reaction with microcosmic salt.

|

Leucite | Some varieties, when treated with cobalt solution,

| assume a blue color.

|

Meerschaum | In the glass bulb frequently blackens and evolves an

| empyreumatic odor due to organic matter. When this is

| burnt off, it again becomes white, and if moistened

| with nitrate of cobalt solution and heated, assumes

| a pink color.

|

Okenite | Behaves as Apophyllite.

|

Olivine | Some varieties give off fluorine, when fused with

| microcosmic salt.

|

Pectolite | Similar to Apophyllite.

|

Petalite | Imparts a slight crimson color to the flame, like

| Lepidolite.

|

Prehnite | As Chabasite.

|

Pycnite | Assumes a blue color, when treated with nitrate of

| cobalt. Gives the fluorine reaction with microcosmic

| salt.

|

Pyrope | Gives the chromium reaction with borax and microcosmic

| salt.

|

Scolecite | Similar to Laumonite, but more marked.

|

Scapolite | Occasionally contains a small quantity of lithia, and

| colors the flame red when fused with fluorspar and

| bisulphate of potassa.

|

Sodalite | If mixed with one-fifth its volume of oxide of copper,

| moistened to make the mixture cohere, and a small

| portion placed upon charcoal and heated with the blue

| oxidizing flame, the outer flame will be colored

| intensely blue from chloride of copper.

|

|

Spodumene | When not too strongly heated, colors the blowpipe

| flame red, when more strongly, yellow.

|

Stilbite | As Chabasite.

|

Topaz | When heated, remains clear. Otherwise as Pycnite.

|

Tourmaline | Gives the boracic acid reaction with flourspar and

| bisulphate of potassa.

|

Wollastonite | Colors the blowpipe flame faintly red from lime.

|

Zircon | The colored varieties become white or colorless and

| transparent, when heated. Is only slightly attacked

| by carbonate of soda.

______________|________________________________________________________

* * * * *

URANIUM.

* * * * *

Mineral. Pitchblende

Formula. [.U][...U=] essentially.

Behavior

(1) in glass-bulb. Evolves some water and a small quantity of

sulphur, sulphide of arsenic and metallic

arsenic.

(2) in open tube. Evolves SO^{2} and a white sublimate of

arsenious acid.

(3) on charcoal. Gives off arsenical fumes.

(4) in forceps. III. Colors the flame blue beyond the assay,

owing to the presence of Pb. Sometimes also

green towards the point, due to Cu.

(5) in borax. The roasted mineral affords the uranium

reaction.

(6) in mic. salt. As borax. Also a small residue of silica.

(7) with carb. soda. Infusible. Affords the characteristic Pb

incrustation, and sometimes yields minute

particles of Cu.

(8) Special reactions. --

* * * * *

Mineral. Uranium ochre

Formula.

[...U=][.H]^{2}.

Behavior

(1) in glass-bulb. Evolves water and assumes a red color.

(2) in open tube. --

(3) on charcoal. V. In reducing flame assumes a green color.

(4) in forceps. --

(5) in borax. Gives the uranium reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. --

(8) Special reactions. --

* * * * *

Mineral. Uranite

Formula. ([.Ca] +[...U=]^{2})[.....]P + 8[.H].

Behavior

(1) in glass-bulb. Evolves water and becomes yellow and opaque.

(2) in open tube. --

(3) on charcoal. Fuses with intumescence to a black bead having a

semi-crystalline surface.

(4) in forceps. --

(5) in borax. Gives the uranium reaction.

(6) in mic. salt. As in borax.

(7) with carb. soda. Forms an infusible yellow slag.

(8) Special reactions. Gives the PO^{5} reaction.

* * * * *

Mineral. Chalcolite

Formula. ([.Cu]+[...U=]^{2})[.....P] + 8[.H].

Behavior

(1) in glass-bulb. As uranite.

(2) in open tube. --

(3) on charcoal. As uranite.

(4) in forceps. As uranite.

(5) in borax. In the oxidizing flame gives a green bead, which

in the reducing flame becomes of an opaque red,

from Cu.

(6) in mic. salt. As in borax.

(7) with carb. soda. In reducing flame yields a metallic bead of Cu.

(8) Special reactions. As uranite.

* * * * *

IRON.

* * * * *

Mineral. Iron pyrites

Formula. FeS^{2}.

Behavior