(8) Special reactions.  Fused with potassa in platinum has no action on
                         silver.  Cobalt-solution produces the alumina
                         reaction.

* * * * *

Mineral.  Native Alum

Formula. [.R][...S] + [...Al][...S]^{3} + 24[.H].

Behavior

  (1) in glass-bulb.  Intumesces greatly and gives off much water. 
                         Strongly heated, evolves SO^{3}, which reddens
                         litmus.

  (2) in open tube. —­

  (3) on charcoal.  Intumesces and become infusible.

  (4) in forceps.  V. Colors the flame violet if a potassa
                         alum—­yellow if soda—­be present.

  (5) in borax.  Dissolves and gives the iron and manganese
                         reaction, if these oxides be present.  Otherwise
                         the bead is colorless.

  (6) in mic. salt.  As in borax.

  (7) with carb. soda.  The alkali is absorbed into the charcoal,
                         leaving an infusable mass which gives the sulfur
                         reaction on silver.

  (8) Special reactions.  If not containing too much iron or manganese
                         gives an alumina reaction with nitrate of of
                         cobalt.  In other respects as the preceding.

* * * * *

Mineral.  Turquoise

Formula.                 [...Al=]^{2}[.....P] + 5[.H].

Behavior

  (1) in glass-bulb.  Evolves water, occasionally decrepitates and
                         turns black.

  (2) in open tube. —­

  (3) on charcoal.  Turns brown, but remains infusible.

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

  (5) in borax.  In the oxidizing flame, gives a green bead, due
                         to copper and iron.  In reducing flame, opaque red.

  (6) in mic. salt.  As in borax.

  (7) with carb. soda.  Intumesces, then fuses to a semi-clear glass
                         colored by iron.  With more alkali yields an
                         infusible mass.

  (8) Special reactions.  Gives the phosphoric-acid reaction.

* * * * *

Mineral.  Wavellite

Formula.                 [Al=]F^{3} + 3([...Al=]^{4}[.....P]^{3} + 18[.H].)

Behavior

  (1) in glass-bulb.  Evolves water and some fluorine, which attacks
                         the glass.

  (2) in open tube. —­

  (3) on charcoal.  Exfoliates and turns white.

  (4) in forceps.  V. As on charcoal.  Colors the outer flame green,
                         especially if moistened with SO^{3}.