(5) in borax.  Gives the bismuth and also an iron reaction.

  (6) in mic. salt.  As in borax, but leaves a silicious skeleton.

  (7) with carb. soda.  Fuses to a yellow mass.  The bismuth is then
                         reduced to the metallic state and partially
                         volatilized, incrusting the charcoal beyond.

  (8) Special reactions. —­

* * * * *

Mineral.  Tetradymite

Formula.  Bi, Te, S.

Behavior

  (1) in glass-bulb.  Occasionally decrepitates and then fuses,
                         forming a greyish white sublimate immediately
                         above the mineral fragment.

  (2) in open tube.  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 (TeO^{3}).  The mineral residue
                         becomes surrounded by fused [...Bi=],
                         characterized by its yellow color.

  (3) on charcoal.  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].

  (4) in forceps. —­

  (5) in borax.  The yellow oxide obtained upon charcoal gives
                         the bismuth reaction, and the white incrustation
                         of bismuth and telluric acid.

  (6) in mic. salt.  As in borax.

(7) with carb. soda.  In the reducing flame yields a bead of metallic
bismuth, part of which is part of the tellurium
volatilized and incrusts the charcoal around.

(8) Special reactions.  The fused alkaline mass gives the sulphur
reaction on silver.  Also gives the tellurium
reaction with charcoal and carbonate of soda.

* * * * *

LEAD.

* * * * *

Mineral.  Galena

Formula.  PbS.

Behavior

(1) in glass-bulb.  Generally decrepitates and gives off a small
quantity of sulphur.

  (2) in open tube.  Gives off SO^{2}, and when strongly heated, a
                         white sublimate of [.Pb], [.S].

  (3) on charcoal.  Fuses and is reduced affording a bead of
                         metallic lead, and forming an incrustation of
                         PbO on the charcoal.  Colors the outer flame
                         blue.