A System of Instruction in the Practical Use of the Blowpipe / Being A Graduated Course Of Analysis For The Use Of Students And All Those Engaged In The Examination Of Metallic Combinations

by Anonymous

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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 faintiron-reaction.	As in borax.	Behaves as magnesia.	With nitrate of cobalt, gives the magnesiareaction
Epsomite	. ... . MgS + 7H.
Evolves water having an acid reaction on testpaper.	—	Gives of HO and SO3, shines brilliantly, andbecomes alkaline and caustic.	V. As on charcoal.	Behaves as magnesia.	As in borax.	The alkali is absorbed leaving the magnesiaon surface of the charcoal. Gives thesulphur-reaction on silver.	The magnesian residue obtained on treating withcarbonate 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 crystallinebead.	I. As on charcoal. Colors the flame green.	Fuses easily to a clear bead, which iscrystalline, when containing much of themineral, and is usually slightly tinted byiron.	As in borax.	With a small quantity of alkali fuses to a clearbead on cooling. With a larger quantity gives aclear, uncrystallizable bead.	—
Magnesite	. .. MgC.
Sometimes gives off a small quantity of water.	—	Is infusible. With cobalt-solution, assumes adusky flesh tint.	—	Behaves as magnesia. Sometimes a slightiron-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 withcarbonate of soda gives the magnesian-reactionwith nitrate of cobalt. Dissolves witheffervescence 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 darkcolor from iron and manganese.	Dissolves with effervescense in warm HCl. Withcarbonate of soda and nitre gives amanganese-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 colorlessglass.	As in borax.	—	In fine powder moistened with cobalt-solutionand heated yields a blue color.
Websterite	. ... . AlS + 9H.
Gives off water, and, when heated to incipientredness, sulphurous acid.	—	Gives off water and SO3, leaving an infusiblemass.	V.	Behaves as alumina.	As in borax.	Yields an infusible mass, which laid on silverand moistened, produces a black stain.	Fused with potassa in platinum has no action onsilver. Cobalt-solution produces the aluminareaction.
Native Alum	. ... . ... . R S + AlS3 + 24H.
Intumesces greatly and gives off much water.Strongly heated, evolves SO3, which reddenslitmus.	—	Intumesces and become infusible.	V. Colors the flame violet if a potassaalum—yellow if soda—be present.	Dissolves and gives the iron and manganesereaction, if these oxides be present. Otherwisethe bead is colorless.	As in borax.	The alkali is absorbed into the charcoal,leaving an infusible mass which gives the sulfurreaction on silver.	If not containing too much iron or manganesegives an alumina reaction with nitrate of ofcobalt. In other respects as the preceding.
Turquoise	... . .. . Al2P + 5H.
Evolves water, occasionally decrepitates andturns 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 morealkali yields an infusible mass.	Gives the phosphoric-acid reaction.
Wavellite	... ... .. . AlF3 + 3(Al4P3 + 18H.)
Evolves water and some fluorine, which attacksthe 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 ironreaction.	As in borax.	Forms an infusible white mass.	With cobalt-solution on charcoal gives thealumina 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 aluminareaction. With nitre and carbonate of soda aslight 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.