Part III (continued 2)

(γ.) Stannic Acid (peroxide, SnO²).—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.

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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.

(χ.) Protoxide of Mercury (Hg²O).—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.

(β.) 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.

(β.) Arsenious Acid (AsO³).—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.

(γ.) Arsenic Acid (AsO⁵) 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.

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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.

(χ.) Protoxide of Copper (Cu²O).—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.

(β.) 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.

(χ.) Protoxide of Silver (Ag²O).—It is a black powder. It is converted by acids and ammonia into oxide and metal.

(β.) 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.

(γ.) Superoxide or Binoxide of Silver (AgO²).—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).

(χ.) Protoxide of Gold (Au²O).—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.

(χ.) Peroxide of Gold (Au²O³).—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.

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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.

(χ.) Protoxide of Molybdenum (MoO).—This oxide is a black powder.

(χ.) Deutoxide of Molybdenum (MoO²).—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 (OsO²) 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.

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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.

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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 (NO⁵).—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 (PO⁶).—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, SO³) 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 (BO³).—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 (SiO³).—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]

(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.

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.

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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.

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.Formula.

Behavior in glass-bulb.on platinum foil.

DiamondC

—In fine powder is slowly consumed without residue in a strong oxidizing Flame.

Graphite C with some iron silica, etc.

Generally gives off water. Is slowly consumed leaving more or less ash, principally Fe²O³.

Anthracite . C + xH

Evolves water. Is slowly consumed with the exception of a small quantity of ash.

Wallsend-coal C, H, O, S and ash.

Intumesces and gives off water and tarry matters which partly condense in bulb, and leave a porous coke. 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.

Cannel-coal C, H, N, O, S and ash.

As the preceding but gives off more tar.Similar to the preceding. If held to the lamp-flame, takes fire and burns for some seconds.

Brown-coal C, H, N, O, S, and ash.

Gives off much water and tar, and leaves a porous cinder retaining the form of the original fragment. Burns slowly and without flame, leaving some ash.

Asphaltum C + H + O.

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. Takes fire and burns with a bright flame and a thick smoke.

Elaterite C + H.

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. 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.

Hachettine C + H.

Fuses to a clear colorless liquid, which solidifies on cooling and has a tallow-like smell. Fuses, takes fire, and burns with a bright flame until entirely consumed.

Ozokerite C + H.

Fuses readily to a clear brown oily fluid, which solidifies on cooling.As the preceding.

Amber C + H + O.

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. Takes fire and burns with a yellow flame and a peculiar aromatic odor.

Mellite ... . AlM³ + 15H

Gives off water. If heated to redness, is carbonized, and gives a slight empyreumatic odor. On charcoal burns to a white ash, which moistened with nitrate of cobalt and heated shows the alumina reaction.

POTASH.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Nitre ... . .. K N

Fuses readily to a clear liquid and with a strong heat boils with the evolution of oxygen. — Deflagrates leaving a saline mass, which is absorbed into charcoal and gives a sulphur reaction on silver. On platinum wire fuses and colors the flame violet more or less modified by lime and soda. — — — With bisulphate of potassa in the glass-bulb evolves nitrous fumes.

Polyhalite . ... . ... . ... . K S + MgS + 2CaS + 2H

Gives off water. — Fuses to a reddish bead, which in the reducing flame solidifies and shrinks to a hollow crust. On platinum wire fuses and colors the flame yellow from a small quantity of soda. Dissolves with ebullition to a clear glass, which is slightly colored by iron, and when saturated become opaque on cooling. As in borax. Fuses. The alkalies are absorbed by the charcoal leaving the lime and magnesia infusible on the surface. The alkaline mass when laid on silver gives a sulphur reaction.

SODA.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Rock-salt NaCl.

Fuses to a clear liquid. — Fuses, is absorbed by the charcoal and partially volatilized incrusting the charcoal around. Fuses with great ease and colors the flame yellow. — — — Gives the chlorine reactions.

Natron . .. . NaC + 10H

Fuses, with the evolution of water. — Fuses, and is absorbed into the pores of the charcoal. Fuses and behaves as the preceding. — — — Dissolves in acid with violent effervescence.

Soda-nitre ... . .. NaN.

Fuses and if strongly heated evolves nitrous fumes. — Deflagrates and is absorbed into the charcoal. Deflagrates on platinum wire, coloring the flame yellow. — — — In a glass-bulb with bisulphate of potassa, gives the NO⁵-reaction.

Glauber-salt . ... . NaS + 10H.

Fuses and gives off water having a neutral reaction. — Fuses, and is absorbed by the charcoal. The saturated charcoal laid upon silver gives the sulphur reaction Fuses and colors the flame yellow. — — — Gives the SO³-reaction.

Glauberite . ... . ... NaS + CaS.

Decrepitates with the evolution of more or less water, and when strongly heated fuses to a clear liquid. — 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. Fuses easily to a clear glass, coloring the flame yellow. Fuses easily and gives the lime reaction. As in borax. As alone in charcoal. As in preceding.

Borax . ... . NaB² + 10H.

Intumesces with the evolution of water, and under a strong heat fuses. — Intumesces and fuses to a clear bead more or less colored by impurities. As on charcoal. — — Fuses to a clear bead, which becomes crystalline on cooling. Gives the boracic-acid-reaction.

Cryolite 3NaFl+Al²Fl³.

Decrepitates slightly and gives a trace of water. 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. 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. Fuses, coloring the flame yellow. Dissolves to a clear bead, which is rendered opaque by a large addition. As in borax. Fuses to a clear bead, then spreads out on the charcoal, the soda is absorbed, and an infusible mass of alumina remains. If the alumina residue obtained be moistened with cobalt solution and heated strongly, it assumes a beautiful blue color.

BARYTA AND STRONTIA.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Heavy-spar . ... BaS.

Sometimes decrepitates and gives off more or less water — Fuses in the reducing flame. Fuses with difficulty on edges. Colors the outer flame green. In reducing flame forms BaS, which fuses readily. Gives the baryta-reaction. As in borax. Fuses to a clear bead; then spreads out and is absorbed into the charcoal. The fused mass laid on silver gives the S-reaction. If fused with potassa on platinum, gives the SO³-reaction.

Celestine . ... SrS.

— — Fuses to a milk-white bead. Colors the flame crimson. Gives the strontia-reaction. As in borax. Similar to the preceding. Similar to the preceding.

Witherite . .. BaC.

Decrepitates more or less and evolves Water. — Fuses, effervesces, and is partially absorbed by the charcoal. Colors the outer flame intensely green. Dissolves with effervescence and gives the baryta-reaction. As in borax. Fuses to a clear bead; then spreads out and passes into the charcoal. In dilute HCl dissolves with much effervescence.

Strontianite . .. SrC.

Becomes opaque. — As in the forceps. Exfoliates and becomes arborescent. The filaments glow brilliantly and fuse on the point. Colors the flame brilliantly crimson. Resembles the preceding. As in borax. As the preceding. As the preceding.

Barytocalcite. . .. . .. BaC + CaC.

As in the preceding. — In powder frits together, but does not fuse. Colors the flame green in the centre and red towards the point. Dissolves with effervescence. In large quantities gives a semi-crystalline bead. As in borax, but the saturated bead is milk-white. Fuses, and is partially absorbed leaving the lime on the surface. As witherite.

LIME.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Gypsum . ... . CaS + 2H.

Turns white, giving off water and being converted into plaster of Paris. — 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. Fuses with difficulty to a bead, coloring the flame red. Dissolves to a clear bead, which gives the lime-reaction. As in borax. Behaves as lime. The alkaline mass laid on silver and moistened gives the sulphur-reaction. Gives the sulphuric-acid reaction.

Apatite ... . {Cl . .. Ca{—— + 3Ca³P {Fl

Occasionally decrepitates and gives off some water. — — IV. Previously dipped in SO³ colors the flame green, afterwards red. Dissolves easily and when in some quantity gives an opaline bead. Gives the lime-reaction. Is infusible. The alkali is absorbed, leaving the lime on the on the surface of the charcoal. With microcosmic salt and oxide of copper, gives the chlorine-reaction. With microcosmic salt in the open tube evolves fluorine.

Pharmacolite . ... . Ca²As + 6H.

Gives off water, and emits an arsenical odor. — Fuses to an opaque bead and emits a strong smell of arsenic. Fuses to a translucent violet colored bead, the color being due to cobalt. Colors the flame blue at first, then faintly red. Dissolves readily to a bead strongly colored by cobalt, which obscures the lime-reaction. As in borax. Fuses, and emits As. The alkali is then absorbed by the charcoal, as in the preceding. —

Calespar . .. CaC.

Turns white and sometimes decrepitates. Strongly heated loses CO² and becomes caustic. — Turns white, or brown if containing much iron or manganese and glows brilliantly. Glows brilliantly, coloring the flame red. Becomes caustic and shows a strong alkaline reaction. Dissolves with evolution of CO² and when pure gives the lime-reaction. The bead is generally more or less colored by iron and manganese. As in borax. Fuses, and behaves as other lime-salts. Dissolves with effervescence in cold HCl.

Fluorspar CaFl

Phosphoresces with various colors, when heated in the dark. — Fuses easily to a clear bead, which becomes opaque on cooling, then loses fluorine, glows brilliantly and becomes infusible. As on charcoal. Colors the flame red. Gives the lime-reaction. As in borax. Fuses to a clear bead, opaque on cooling. With an addition of the alkali behaves as lime. With microcosmic salt in open tube gives the fluorine-reaction.

MAGNESIA.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Brucite . . MgH.

Evolves water. — — V. Behaves as magnesia. Sometimes gives a faint iron-reaction. As in borax. Behaves as magnesia. With nitrate of cobalt, gives the magnesia reaction

Epsomite . ... . MgS + 7H.

Evolves water having an acid reaction on test paper. — Gives of HO and SO³, shines brilliantly, and becomes alkaline and caustic. V. As on charcoal. Behaves as magnesia. As in borax. The alkali is absorbed leaving the magnesia on surface of the charcoal. Gives the sulphur-reaction on silver. The magnesian residue obtained on treating with carbonate of soda (7), assumes a flesh-tint, when treated with cobalt.

Boracite . ... . ... MgB² + 2MgB.

Occasionally gives off a trace of water. — Fuses with intumescence to a white crystalline bead. I. As on charcoal. Colors the flame green. Fuses easily to a clear bead, which is crystalline, when containing much of the mineral, and is usually slightly tinted by iron. As in borax. With a small quantity of alkali fuses to a clear bead on cooling. With a larger quantity gives a clear, uncrystallizable bead. —

Magnesite . .. MgC.

Sometimes gives off a small quantity of water. — Is infusible. With cobalt-solution, assumes a dusky flesh tint. — Behaves as magnesia. Sometimes a slight iron-reaction. As in borax. Fuses to a bead, the soda is then absorbed, leaving an infusible mass of magnesia. The magnesian residue obtained by fusing with carbonate of soda gives the magnesian-reaction with nitrate of cobalt. Dissolves with effervescence in warm HCl.

Mesitine spar . . . .. (MgFeMn)C.

As magnesite. — Is infusible. Assumes a deep brown color. V. Gives the iron and manganese-reaction. As in borax. As magnesite, but the residual mass has a dark color from iron and manganese. Dissolves with effervescense in warm HCl. With carbonate of soda and nitre gives a manganese-reaction.

ALUMINA.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Sapphire Corundum Emery ... Al.

— — — V. In fine powder dissolves slowly to a colorless glass. As in borax. — In fine powder moistened with cobalt-solution and heated yields a blue color.

Websterite . ... . AlS + 9H.

Gives off water, and, when heated to incipient redness, sulphurous acid. — Gives off water and SO³, leaving an infusible mass. V. Behaves as alumina. As in borax. Yields an infusible mass, which laid on silver and moistened, produces a black stain. Fused with potassa in platinum has no action on silver. Cobalt-solution produces the alumina reaction.

Native Alum . ... . ... . R S + AlS³ + 24H.

Intumesces greatly and gives off much water. Strongly heated, evolves SO³, which reddens litmus. — Intumesces and become infusible. V. Colors the flame violet if a potassa alum—yellow if soda—be present. Dissolves and gives the iron and manganese reaction, if these oxides be present. Otherwise the bead is colorless. As in borax. The alkali is absorbed into the charcoal, leaving an infusible mass which gives the sulfur reaction on silver. If not containing too much iron or manganese gives an alumina reaction with nitrate of of cobalt. In other respects as the preceding.

Turquoise ... . .. . Al²P + 5H.

Evolves water, occasionally decrepitates and turns black. — Turns brown, but remains infusible. V. As on charcoal. Colors the outer flame green. In the oxidizing flame, gives a green bead, due to copper and iron. In reducing flame, opaque red. As in borax. Intumesces, then fuses to a semi-clear glass colored by iron. With more alkali yields an infusible mass. Gives the phosphoric-acid reaction.

Wavellite ... ... .. . AlF³ + 3(Al⁴P³ + 18H.)

Evolves water and some fluorine, which attacks the glass. — Exfoliates and turns white. V. As on charcoal. Colors the outer flame green, especially if moistened with SO³. As alumina. Generally gives also a slight iron reaction. As in borax. Forms an infusible white mass. With cobalt-solution on charcoal gives the alumina reaction.

Spinel . ... R Al.

— — — V. Gives a slight iron reaction. As in borax. Fuses partially and forms a porous mass. With nitrate of cobalt gives the alumina reaction. With nitre and carbonate of soda a slight manganese reaction.

SILICATES.

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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.

Readily fusible to a bead.

With difficulty fusible to a bead.

Readily fusible on the edges.

With difficulty fusible on the edges.

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 . . ... ... ... ... ... ... ... (CaMg)³ ( B Si )³ + ( Al Fe Mn)²( Si B )Int.

Elaolite . . ... ... ... (KNa)³Si + 3 Al SiInt.

Garnet . ... . ... R³Si + R Si

Oligoclase . ... ... ... NaSi + Al Si²

Scapolite . . ... ... ... (CaNa)³Si² + 2 Al SiInt.

Spodumene . . ... ... ... (LiNa)³Si² + 4 AlSi²Int.

b.Asbestos to II.As Hornblende

Augite some var. . . . . ... (CaMgFeMn)³Si²Int.

Epidote to III. . ... ... ... ... ... (CaFe)³Si + 2( Al Fe Mn )SiInt.

Hornblende some var. . . . ... ... (CaMgFe)⁴ + ( Si Al )³Int.

Sodalite to III. . ... ... ... Na³Si + 3 Al Si + NaClInt.

Vesuvian . . ... ... ... ... 3(CaMg)³Si + 2( Al Fe )SiInt.

c.Biaxial Mica to III. . ... ... ... ... K Si + 4( Al Fe )Si

Hauyne . . ... ... ... . ... (KNa)³Si + 3 Al Si + NaSi

Tourmaline to V. . ... ... ... (R R B )⁴ Si³Int.

II.

a.Labradorite . . . ... ... ... ... (CaNaK)Si + ( Al Fe) Si

Lepidolite ... ... ... (KNaL)F + (Al Fe) Si²?

Ryacolite . ... ... ... K Si + Al Si²

Albite . ... ... ... NaSi + Al Si³

b.Augite some var. . ... R³Si²

Actinolite . . . ... (CaMgFe)⁴Si³Int

Diopside . . ... (CaMg)³Si²

Humboltilite . . . . ... ... ... ... 2(CaMgNaK)Si + ( Al Fe )Si

SahliteAs Augite

Tremolite . . ... (CaMg)⁴Si³

c.Pyrope . . . ... ... ... ... (CaMgFe)³Si + Al Si + mCr?

III.

a.Anorthite . . . . ... ... ... ... (CaMgNaK)³Si + 3( Al Fe )Si

Nepheline . . . ... ... ... (NaKCa)²Si + 2 Al Si

Obsidian ... ... ... . . . . Si, Al, Fe, Fe, CaNaKInt.

Orthoclase . . ... ... ... (KNa)Si + Al Si³

Petalite . . ... ... ... (LiNa)³Si⁴ + 4 Al Si⁴

Pumice ... ... . . . . Si, Al, Ca, K, Na, HInt.

b.Gadolinite to V. . . . . . ... (YCeLaFeCa)³Si

Nephrite . . . ... (CaMgFe)⁴Si³?Int.

Wollastonite . ... Ca³Si²

c.Iolite . . ... ... ... (MgFe)³Si² + 3 Al Si

IV.

a.Beryl ... ... ... ... Be Si² + Al Si²

b.Diallage . . . ... ... (CaMgFe)³( Si Al)²

Hypersthene . . ... (MgFe)³Si²

c.Fuchsite . ... ... ... ... (K⁵Si )² + 9( Al Cr)⁶Si⁶

V.

a.Leucite . ... ... ... K³Si² + Al Si²

b. Chondrodite . . ... (Mg, MgF)⁴( SiSiF³)

Olivine . . . ... (MgFeCa)²Si

c.Andalusite ... ... ... ( Al Fe)³Si²

Chrysoberyl ... ... Be + Al

Kaynite ... ... Al³Si²

Pycnite Topaz ... ... ... 6Al ³Si² + (3 AlF³ + 2SiF³)

Zircon ... ... Zr Si

Staurolite ... ... ... (Al Fe)² Si

Hydrous Silicates.

Fus. alone and with NaC.

Mineral.Formula.

I.

a.Analcime. ... ... ... . Na³Si² + 3Al Si² + 6HInt.

Apophyllite . ... . ... . (K,KF)(Si, SiF³) + 6CaSi + 15HInt.

Brewsterite . . ... ... ... . (SrBa)Si + Al Si³ + 5HInt.

Chabasite . . . ... ... ... . (Ca,Na,K)³Si + 3 Al Si² + 18HInt.

Lapis Lazuli ... ... ... ... . . . Si, S, Al, Fe, Ca, Na, H

Laumonite . ... ... ... . Ca³Si² + 3 Al Si² + 12HInt.

Mesotype . . ... ... ... . (NaCa)Si + Al Si + 3HInt.

Natrolite . ... ... ... . NaSi + Al Si + 2HInt.

Prehnite . ... ... ... . Ca²Si + Al Si + HInt.

Scolezite . ... ... ... . CaSi + Al Si + 3HInt.

Thomsonite . . ... ... ... . (CaNa)³Si + 3 Al Si + 7HInt.

Datholite . ... ... ... . 2Ca³Si + B³ Si² + 3HInt.

Heulandite . ... ... ... . CaSi + Al Si³ + 5HInt.

Stilbite . ... ... ... . CaSi + Al Si³ + 6HInt.

b.Okenite . ... . Ca³Si⁴ + 6HInt.

Pectolite . . ... . (CaNa)⁴Si³ + HInt.

c.Saponite . ... ... ... . 2Mg³Si² + Al Si + 10 or 6H

II.

a.Antrimolite . . ... ... ... . 3(CaK)Si + 5 Al Si + 15H

Harmatome . ... ... ... . BaSi + Al S² + 5H

b.Brevicite . ... ... ... . NaSi + Al Si + 2H

Orthite . ... ... ... . R³Si + R Si + (H?)Int.

III.

c.Pitchstone ... ... ... . . . . Si, Al, Fe, MgNa, KH

Talc to V. . ... . Mg⁶Si⁵ + 2H

Chlorite . . ... ... ... ... . 3(MgFe)³Si + ( Al Fe )²Si + 9H

Pinite ... ... . . . . Si, Al, Fe, K, Mg, H

IV.

a.Steatite . ... . Mg⁶Si⁵ + 4H

c.Gilbertite ... ... . . . Si, Al, Fe, Mg, HInt.

Meerschaum . ... . MgSi + H

Serpentine . ... . Mg⁹Si⁴ + 6H

V.

a.Gismondine . . ... ... ... . (CaK)²Si + 2 Al Si + 9H

TABLE II.

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AnalcimeIf transparent becomes white and opaque when heated, but on incipient fusion resumes its transparency and then fuses to a clear glass.

AndalusiteWhen powdered and treated with cobalt solution on charcoal, assumes a blue color.

ApophylliteFuses to a frothy white glass.

AxiniteImparts 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.

BerylSometimes gives a chromium reaction in borax and microcosmic salt.

ChabasiteFuses to a white enamel.

ChondroditeEvolves fluorine in the glass tube, both when heated alone and with microcosmic salt. It sometimes also gives off a trace of water.

ChrysoberylIs unattacked by carbonate of soda. With nitrate of cobalt on charcoal the finely powdered mineral assumes a blue color.

DatholiteFuses to a clear glass and colors the flame green.

DiallageFrequently gives off water in small quantity.

FuchsiteGives the chromium reaction with borax and microcosmic salt.

GadoliniteThat 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.

HyperstheneAs Diallage.

KyaniteAs Andalusite.

Lapis LazuliFuses to a white glass, and when treated with carbonate of soda on charcoal, gives the sulphur reaction on silver.

LaumoniteWhen strongly heated, exfoliates and curls up.

LepidoliteColors the blowpipe flame crimson, from lithia; also gives the fluorine reaction with microcosmic salt.

LeuciteSome varieties, when treated with cobalt solution, assume a blue color.

MeerschaumIn 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.

OkeniteBehaves as Apophyllite.

OlivineSome varieties give off fluorine, when fused with microcosmic salt.

PectoliteSimilar to Apophyllite.

PetaliteImparts a slight crimson color to the flame, like Lepidolite.

PrehniteAs Chabasite.

PycniteAssumes a blue color, when treated with nitrate of cobalt. Gives the fluorine reaction with microcosmic salt.

PyropeGives the chromium reaction with borax and microcosmic salt.

ScoleciteSimilar to Laumonite, but more marked.

ScapoliteOccasionally contains a small quantity of lithia, and colors the flame red when fused with fluorspar and bisulphate of potassa.

SodaliteIf 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.

SpodumeneWhen not too strongly heated, colors the blowpipe flame red, when more strongly, yellow.

StilbiteAs Chabasite.

TopazWhen heated, remains clear. Otherwise as Pycnite.

TourmalineGives the boracic acid reaction with flourspar and bisulphate of potassa.

WollastoniteColors the blowpipe flame faintly red from lime.

ZirconThe colored varieties become white or colorless and transparent, when heated. Is only slightly attacked by carbonate of soda.

URANIUM.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Pitchblende . ... U U essentially.

Evolves some water and a small quantity of sulphur, sulphide of arsenic and metallic arsenic. Evolves SO² and a white sublimate of arsenious acid. Gives off arsenical fumes. III. Colors the flame blue beyond the assay, owing to the presence of Pb. Sometimes also green towards the point, due to Cu. The roasted mineral affords the uranium reaction. As borax. Also a small residue of silica. Infusible. Affords the characteristic Pb incrustation, and sometimes yields minute particles of Cu. —

Uranium ochre ... . U H².

Evolves water and assumes a red color. — V. In reducing flame assumes a green color. — Gives the uranium reaction. As in borax. — —

Uranite ... . ... .. . (Ca + U²)P + 8H.

Evolves water and becomes yellow and opaque. — Fuses with intumescence to a black bead having a semi-crystalline surface. — Gives the uranium reaction. As in borax. Forms an infusible yellow slag. Gives the PO⁵ reaction.

Chalcolite ... . ... .. . (Cu + U²)P + 8H.

As uranite. — As uranite. As uranite. In the oxidizing flame gives a green bead, which in the reducing flame becomes of an opaque red, from Cu. As in borax. In reducing flame yields a metallic bead of Cu. As uranite.

IRON.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Iron pyrites FeS².

Gives a considerable yellow sublimate of sulphur, and sometimes sulphide of arsenic. Also HS. Sulphurous acid and sometimes arsenious acid are evolved. Gives off some sulphur, which burns with a blue flame. Residue fuses to a magnetic bead. — The roasted mineral gives a strong iron reaction. As in borax. Fuses to a black mass, which spreads out on charcoal and gives the sulphur reaction on silver. —

Magnetic pyrites , ,,, Fe⁵Fe.

— Evolves sulphurous acid. Fuses to a magnetic bead black on the surface, and with a yellow shining fracture. — As iron pyrites. As in borax. As iron pyrites. —

Mispickel FeAs + FeS².

A red sublimate of AsS² is first formed and then a black sublimate of metallic arsenic. Sulphurous and arsenious acids are evolved, the latter forming a white sublimate. Gives off much arsenic forming a white incrustation and fuses to a magnetic globule. — As iron pyrites. As in borax. As iron pyrites. —

Magnetic iron ore Fe³O⁴

— — — In the blue flame, fuses on edges and remains magnetic. Gives the iron reaction. As in borax. — —

Specular iron Red haematite Fe²O³

— — — V. In the blue flame is converted into Fe²O⁴, and then behaves as the preceding. As magnetic iron ore. As in borax. — —

Göthite ... . Fe H.

Evolves water. — — As specular iron. As specular iron. As in borax. — —

Franklinite . . . ... ... (FeZnMn)(Fe Mn).

— — Forms a white incrustation on the charcoal, which moistened with cobalt solution assumes a green color. V. In the blue flame fuses on edges and and becomes magnetic. Gives the iron and manganese reaction. As in borax. Affords a considerable white incrustation of ZnO. Gives a strong manganese reaction with nitre and carbonate of soda.

Ilmenite ... ... Ti and Fe.

— — — V. In reducing flame fuses on edges and becomes magnetic. Gives the iron reaction. In oxidizing flame exhibits the iron reaction. In reducing flame assumes a deep brownish red color. — —

Chromic iron . ... FeCr.

— — — As the preceding. Dissolves slowly and gives the chromium reaction. As in borax. On platinum foil with nitre and carbonate of soda affords a yellow mass of chromate of potassa. —

Lievrite . . ... ... ... 3(FeCa)³Si + 2Fe Si.

Occasionally gives off some water and turns black. — Fuses to a black globule, which in the reducing flame becomes magnetic. I. In reducing flame is magnetic. Gives the iron reaction. Gives the iron and silica reactions. Fuses to a black opaque bead. Generally gives the manganese reaction with nitre and carbonate of soda.

Chloropal ... ... . Fe Si² + 3H.

Decrepitates more or less, gives off much water and turns black. — — V. Loses color and turns black. Gives the iron reaction. Gives the iron and silica reaction. Fuses to a transparent green glass. —

Green earth ... . ... . . . Si, Fe, Al, Na, K, H, etc.

Gives off water and becomes darker in color. — — V. In reducing flame fuses on edges and colors the outer flame yellow . (Na) or violet . (K). As the preceding. As the preceding. Forms a slaggy mass. —

Siderite . .. FeC.

Occasionally decrepitates. Gives off CO² and turns black and magnetic. — As in glass bulb. Behaves similarly to the magnetic oxide. Gives the iron and manganese reaction. As in borax. Behaves as an oxide. With nitre and carbonate of soda on platinum generally gives the manganese reaction. In acid dissolves with effervescense.

Copperas . ... . Fe S + 7H.

Gives off water, and, when strongly heated, SO² and SO³, which reddens litmus paper. Evolves water and SO², which may be recognized by its odor. Loses water and SO², and is converted into ... Fe. Gives off H and SO², and then behaves as the magnetic oxide. The roasted mineral affords an iron reaction. As in borax. Forms sulphide of sodium and oxide of iron. The former is absorbed into the charcoal, and if cut out and laid upon silver and moistened gives the S reaction. If dissolved in water, and a strip of silver-foil be introduced into the solution, the metal remains untarnished.

Vivianite ... . .. . Fe³P + 8H.

Gives off water. — Froths up and then fuses to a grey metallic bead. As on charcoal. Singes flame green ..... (P). Gives the iron reaction. As in borax. In reducing flame becomes magnetic and fuses to a black saggy mass. —

Iriphyline ... . . . .. (FeMnLi)³P.

Gives off water, having an alkaline reaction, and assumes a metallic lustre resembling graphite. — Fuses readily to a black magnetic bead with a metallic lustre. I. On platinum wire colors the flame crimson . (Li) and green ..... (P), towards the point fuses to a black magnetic bead. Gives the iron and manganese reactions. Gives the iron reaction which overpowers that of the manganese. Forms an infusible porous mass, which under the reducing flame becomes magnetic. Gives the manganese reaction with nitre and carbonate of soda on platinum foil.

Scorodite ... ... .. . FeAs + 4H.

Evolves water. Gives off water and AsO³. Emits arsenical fume and in the reducing flame fuses to a magnetic mass having a metallic lustre. I. As on charcoal. Colors the outer flame blue. The roasted mineral gives an iron reaction. As in borax. As alone on charcoal. Gives the arsenic reactions.

Cube ore ... ... . .. ... .. . Fe³As + Fe³ As² + 18H.

Evolves much water. As the preceding. As the preceding. As the preceding. As the preceding. As in borax. As the preceding. As the preceding.

MANGANESE.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Manganblende MnS.

— Gives off SO² and becomes greyish green on surface. Is slowly roasted and converted into oxide. V. The roasted mineral gives a strong manganese reaction. In the unroasted state, dissolves with much ebullition and detonation due to elimination of sulphide of phosphorus. The bead then exhibits the characteristic violet color of manganese. Forms a slaggy mass, which laid on silver and moistened, gives the sulphur reaction. —

Pyrolusite .. Mn.

Frequently gives off a small quantity of water and, when strongly heated, oxygen. — — V. Gives the manganese reaction. As in borax. Forms a slaggy mass. —

Manganite ... . Mn H.

Gives off much water. — — V. Exfoliates slightly. As the preceding. As in borax. As the preceding. —

Psilomelane . . . . .. . (Ba,Ca,Mg,K)Mn + H.

Gives off water and, when strongly heated, oxygen. — — V.>br />Colors flame faintly green(Ba) and red towards the point (Ca). As pyrolusite. As in borax. As pyrolusite. —

Wad .. . . ... ... . . ... ... Mn, Mn, H, also Fe, Al, Ba, Cu, Pb, Si, etc.

Gives off water. — — V. Colors flame variously according to its composition. Gives the manganese reaction, more or less modified by the presence of other oxides. As in borax. As pyrolusite. Various according to composition. When strongly heated and then moistened has an alkaline reaction on red litmus paper.

Rhodonite . ... Mn³Si².

Gives off more or less water. — Under a strong flame fuses to a brown opaque bead. II. As on charcoal. In the oxidizing flame gives the manganese reaction. In reducing flame the iron reaction. As in borax, but leaves an insoluble siliceous skeleton. With a small quantity of the alkali fuses to a black bead. With a larger quantity forms a slag. —

Diallogite . .. MnC.

Frequently decrepitates and gives off more or less water. — If strongly heated and moistened has an alkaline reaction on litmus paper due to the presence of . Ca. V. Frequently colors the flame slightly red. Gives the manganese and iron reactions. As in borax. Forms an infusible slag. In warm acid dissolves with much effervescence.

Triplite ... .. . .. (MnFe)⁴P.

Generally gives off more or less water. — — I. Colors the outer blowpipe flame green ..... (P). Gives the manganese and iron reactions. As in borax. Forms an infusible mass. —

NICKEL AND COBALT.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Millerite NiS.

— Evolves SO². Fuses with much ebullition to a magnetic bead. — The roasted mineral gives a nickel reaction, slightly modified by small quantities of iron and copper. As in borax. Fuses to a slaggy mass, which on silver gives the sulphur reaction. —

Coppernickel Ni²As.

Gives off a little AsO³. Gives off much AsO³ and some SO² and falls to powder. Fuses to a magnetic bead, with the evolution of arsenic, which colors the flame blue. — The arsenical bead obtained by fusing the mineral on charcoal, if fused upon the same support with borax successively added and removed, gives firstly an iron reaction, then cobalt if present, and lastly nickel. If the residual bead which has been treated with borax be further treated with microcosmic salt, the nickel reaction will be obtained and sometimes a slight copper reaction. — Affords a sublimate of metallic arsenic when treated with cyanide of potassium.

Smaltine CoAs.

When strongly heated generally evolves metallic arsenic. Gives a crystalline sublimate of AsO³. Also some SO². Gives off fumes of arsenic, and fuses to a dark grey magnetic bead, very brittle, colors flame blue. — As the preceding, but the cobalt being in large excess requires some time for its perfect oxidation, before the nickel reaction is exhibited. Gives the cobalt reaction, and after the cobalt has been, removed that of nickel. — As the preceding.

Glance cobalt CoS² + CoAs.

— As the preceding, but gives off more SO². Gives off S and As, and fuses to a magnetic bead. Colors flame blue. — Gives a cobalt and slight iron reaction when treated as the preceding minerals. As in borax. Gives a sulphur reaction of silver. As the preceding.

Nickel glance NiS² + NiAs.

Decrepitates and gives an orange colored sublimate of AsS². As the preceding. As the preceding. — As copper nickel. Gives the nickel reaction occasionally somewhat obscured by cobalt. As the preceding. As copper nickel.

Ulmannite NiS² + Ni(AsSb)².

Gives a slight white sublimate of SbO³ and more or less AsS³. Gives off thick fumes of SbO³ and SbO⁵ with AsO³ and SO². As glance cobalt, but accompanied by dense fumes of SbO³. — As copper nickel. As the preceding. As the preceding. As copper nickel generally, but arsenic is not always present.

Cobalt pyrites , , , ,,, ,,, ,,, (CoNiFe)(Co Ni Fe).

When strongly heated gives off sulphur and becomes brown. Gives off much SO² and a small quantity of AsO³. In the reducing flame small fragments fuse with the evolution of sulphur to a magnetic bead having a bronze colored fracture. — In the oxidizing flame on charcoal gives a violet colored glass. In the reducing flame the nickel is reduced and may collected in a gold bead. When the nickel is removed, the glass exhibits a slight iron reaction while warm. As in borax, but the reduction of the nickel is more difficult than in the latter flux. As glance cobalt. As copper nickel, but the amount of arsenic is usually very small.

Emerald nickel . .. . Ni³C + 6H.

Gives off much water and turns black. — — — Dissolves with much effervescence and gives the nickel reaction. As in borax. Forms a slaggy mass. In warm dilute HCl dissolves with much effervescence.

Cobalt Bloom . ... . Co³As + 8H.

Gives off water. — Evolves arsenical fumes and in the reducing flame fuses to a dark grey bead of arsenide of cobalt. In the point of the blue flame fuses and colors the outer flame blue (As). Gives the cobalt reaction. As in borax. — Gives off arsenic with cyanide of potassium in glass tube.

Earthy cobalt . . . . . Mn,Co,Cu,Fe,H, etc.

Gives off water. — Emits a slight smell of arsenic, but does not fuse. Colors the flame blue. In oxidizing flame gives the cobalt reaction which obscures those of . Mn, . Cu, etc. In reducing flame occasionally gives the . Cu reaction. As in borax. If a saturated bead be treated on charcoal with tin in the reducing flame for a few seconds, the . Cu reaction is sometimes obtained. Forms an infusible mass. With carbonate of soda and nitre on platinum foil, gives a strong manganese reaction.

ZINC.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Zincblende ZnS.

Decrepitates strongly. Evolves SO and becomes white or yellow if containing iron. V. In the reducing flame incrusts the charcoal with ZnO; also with CdO, if that metal be present. — The roasted mineral gives a zinc reaction, and sometimes a slight iron reaction. As in borax. As alone on charcoal. Moreover colors the flame blue. The fused alkali gives a S reaction on silver. —

Red oxide of zinc . Zn.

— — In the reducing flame forms a thin incrustation of oxide of zinc on the charcoal. V. Generally gives a manganese and slight iron reaction in addition to that of zinc. As in borax. On charcoal, forms a thick incrustation of ZnO. With carbonate of soda and nitre on platinum foil gives manganese reaction.

Electric calamine . ... . 2Zn³Si + 3H

Gives off water and becomes white and opaque. — — V. Dissolves to a clear glass, which cannot be rendered opaque by the intermittent flame. Dissolves to a clear glass, which becomes opaque on cooling. Silica remains insoluble. With carbonate of soda alone is infusible. With 2 parts of alkali and 1 of borax fuses to a glass and sets free . Zn, which incrusts the charcoal. —

Calamine . .. ZnC.

Gives off CO² and becomes opaque. — As the red oxide. Sometimes also gives a lead incrustation. V. Gives a zinc reaction and frequently an iron and manganese reaction. As in borax. Forms a thick incrustation of zinc, sometimes also of . Pb and . Co. Dissolves with much effervescence in cold acid.

BISMUTH.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Native bismuth Bi.

— Fuses and is converted into a yellow oxide. Fuses to a bead and incrusts the charcoal with oxide. — The oxide formed upon charcoal gives the bismuth reactions. As in borax. — —

Bismuthine BiS.

— Fuses with ebullition and gives of S and SO². Fuses with much spirting and in the reducing flame yields a metallic bead and incrusts the charcoal with oxide. — The oxide obtained upon charcoal gives the bismuth reactions. As in borax. As alone on charcoal. The fused alkali gives the sulphur reaction on silver. —

Bismuthblende ... ... Bi² Si³.

Turns yellow and, when strongly heated, fuses. — Fuses with ebullition to a brown globule forming an incrustation of ... Bi on the charcoal. I. Fuses with ease to a yellow bead, coloring the outer flame bluish green, especially if moistened with HCl. This color is due to ..... P. Gives the bismuth and also an iron reaction. As in borax, but leaves a silicious skeleton. Fuses to a yellow mass. The bismuth is then reduced to the metallic state and partially volatilized, incrusting the charcoal beyond. —

Tetradymite Bi, Te, S.

Occasionally decrepitates and then fuses, forming a greyish white sublimate immediately above the mineral fragment. Fuses and gives off white fumes, part of which pass up the tube and part deposit immediately above the mineral. This latter if heated fuses to clear drops (TeO³). The mineral residue becomes surrounded by fused ... Bi, characterized by its yellow color. Fuses to a metallic bead, colors the outer flame bluish green (Te and Se) and incrusts the charcoal around with the orange ... Bi, beyond which is a white incrustation partly consisting of ... Te. — The yellow oxide obtained upon charcoal gives the bismuth reaction, and the white incrustation of bismuth and telluric acid. As in borax. In the reducing flame yields a bead of metallic bismuth, part of which is part of the tellurium volatilized and incrusts the charcoal around. The fused alkaline mass gives the sulphur reaction on silver. Also gives the tellurium reaction with charcoal and carbonate of soda.

LEAD.

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Mineral.Formula.

(1) in glass bulb.(2) in open tube.(3) on charcoal.(4) in forceps. (5) in borax.(6) in mic. salt.(7) in carb. soda.(8) Special Reactions.

Galena PbS.

Generally decrepitates and gives off a small quantity of sulphur. Gives off SO², and when strongly heated, a white sublimate of . Pb, . S. Fuses and is reduced affording a bead of metallic lead, and forming an incrustation of PbO on the charcoal. Colors the outer flame blue. — The oxide formed upon charcoal gives the lead reaction. As in borax. As alone on charcoal. The fused alkali gives a sulphur reaction on silver. —

Clausthalite PbSe.

Decrepitates slightly. Forms a sublimate of selenium, which is grey when thickly deposited, and red when thin. Gives off fumes smelling strongly of selenium and coloring the flame blue. In the reducing flame fuses partially and incrusts the charcoal with Se and PbO. After some time a black infusible mass alone remains. — The infusible residue obtained upon charcoal gives an iron and sometimes copper and cobalt reaction. As in borax. With carbonate of soda, oxalate of potash yields a metallic bead, the fused alkali laid upon silver and moistened produces a stain similar to that produced by sulfur. —

Jamesonite , ,,, Pb³Sb².

Fuses and gives off some sulphur, sulphide of antimony and antimony which condense in the neck of the bulb. Fuses and emits dense white fumes of SbO³, which pass off and redden blue litmus paper. Fuses with great ease evolving much SbO³ and PbO, which incrusts the charcoal around the mineral. When the fumes have ceased, a small bead of metallic lead remains. — The yellow incrustation formed upon charcoal gives the reaction of lead, and the white those of antimony. As in borax. As alone on charcoal. The fused alkali gives the sulphur reaction on silver. —

Minium Pb³O⁴.

— — Is reduced first to litharge (PbO) and then to metallic lead which forms the usual incrustation. Colors the outer flame blue. Gives the lead reactions. As in borax. As alone on charcoal. —

Mendipite PbCl + 2PbO.

Decrepitates slightly and assumes a yellow color. — Fuses readily and is reduced to metallic lead with the evolution of acid fumes. Forms a white incrustation of PbCl, and a yellow one of PbO. As the preceding. As the preceding. As in borax. As alone on charcoal. Gives the chlorine reaction with CuO and microcosmic salt.