(8) Special reactions. The magnesian residue obtained on treating with carbonate of soda (7), a.s.sumes a flesh-tint, when treated with cobalt.

Mineral. Boracite

Formula. [.Mg][...B]^{2} + 2[.Mg][...B].

Behavior

(1) in gla.s.s-bulb. Occasionally gives off a trace of water.

(2) in open tube. --

(3) on charcoal. Fuses with intumescence to a white crystalline bead.

(4) in forceps. I. As on charcoal. Colors the flame green.

(5) in borax. Fuses easily to a clear bead, which is crystalline, when containing much of the mineral, and is usually slightly tinted by iron.

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

(7) with carb. soda. With a small quant.i.ty of alkali fuses to a clear bead on cooling. With a larger quant.i.ty gives a clear, uncrystallizable bead.

(8) Special reactions. --

Mineral. Magnesite

Formula. [.Mg][..C].

Behavior

(1) in gla.s.s-bulb. Sometimes gives off a small quant.i.ty of water.

(2) in open tube. --

(3) on charcoal. Is infusible. With cobalt-solution, a.s.sumes a dusky flesh tint.

(4) in forceps. --

(5) in borax. Behaves as magnesia. Sometimes a slight iron-reaction.

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

(7) with carb. soda. Fuses to a bead, the soda is then absorbed, leaving an infusable ma.s.s of magnesia.

(8) Special reactions. The magnesian residue obtained by fusing with carbonate of soda gives the magnesian-reaction with nitrate of cobalt. Dissolves with effervescence in warm HCl.

Mineral. Mesitine spar

Formula. ([.Mg][.Fe][.Mn])[..C].

Behavior

(1) in gla.s.s-bulb. As magnesite.

(2) in open tube. --

(3) on charcoal. Is infusible. a.s.sumes a deep brown color.

(4) in forceps. V.

(5) in borax. Gives the iron and manganese-reaction.

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

(7) with carb. soda. As magnesite, but the residual ma.s.s has a dark color from iron and manganese.

(8) Special reactions. Dissolves with effervescense in warm HCl. With carbonate of soda and nitre gives a manganese-reaction.

ALUMINA.

Mineral. Sapphire Corundum Emery

Formula. [...Al=].

Behavior

(1) in gla.s.s-bulb. --

(2) in open tube. --

(3) on charcoal. --

(4) in forceps. V.

(5) in borax. In fine powder dissolves slowly to a colorless gla.s.s.

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

(7) with carb. soda. --