(2) in open tube. —­

  (3) on charcoal.  Intumesces and fuses to a clear bead more or
                         less colored by impurities.

  (4) in forceps.  As on charcoal.

  (5) in borax. —­

  (6) in mic. salt. —­

  (7) with carb. soda.  Fuses to a clear bead, which becomes crystalline
                         on cooling.

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

* * * * *

Mineral.  Cryolite

Formula. 3NaFl+Al^{2}Fl^{3}.

Behavior

  (1) in glass-bulb.  Decrepitates slightly and gives a trace of
                         water.

  (2) in open tube.  If heated so that the flame be allowed to play
                         up the tube upon the mineral, flourine is
                         evolved, which corrodes the interior of the
                         tube.

  (3) on charcoal.  Fuses to a limpid bead, which on cooling becomes
                         a white enamel.  If heated for some time, it
                         bubbles, gives off fluorine and becomes
                         infusible.

  (4) in forceps.  Fuses, coloring the flame yellow.

  (5) in borax.  Dissolves to a clear bead, which is rendered
                         opaque by a large addition.

  (6) in mic. salt.  As in borax.

  (7) with carb. soda.  Fuses to a clear bead, then spreads out on the
                         charcoal, the soda is absorbed, and an infusible
                         mass of alumina remains.

  (8) Special reactions.  If the alumina residue obtained be moistened
                         with cobalt solution and heated strongly, it
                         assumes a beautiful blue color.

* * * * *

BARYTA AND STRONTIA.

* * * * *

Mineral.  Heavy-spar

Formula. [.Ba][...S].

Behavior

  (1) in glass-bulb.  Sometimes decrepitates and gives off more or
                         less water

  (2) in open tube. —­

  (3) on charcoal.  Fuses in the reducing flame.

  (4) in forceps.  Fuses with difficulty on edges.  Colors the outer
                         flame green.  In reducing flame forms BaS, which
                         fuses readily.

  (5) in borax.  Gives the baryta-reaction.

  (6) in mic. salt.  As in borax.

  (7) with carb. soda.  Fuses to a clear bead; then spreads out and is
                         absorbed into the charcoal.  The fused mass laid
                         on silver gives the S-reaction.