(6) in mic. salt.  As in borax.

  (7) with carb. soda.  As alone on charcoal.  The alkaline mass gives
                         a sulphur reaction on polished silver.

  (8) Special reactions. —­

* * * * *

Mineral.  Stephanite

Formula. [,Ag]^{6}[,,,Sb].

Behavior

  (1) in glass-bulb.  Decrepitates, fuses and gives a slight
                         sublimate of sulphide of antimony.

  (2) in open tube.  Fuses and gives off SO^{2} and dense white
                         antimonial fumes.

  (3) on charcoal.  Fuses and incrusts the charcoal with
                         antimonious acid, leaving Ag with some
                         antimony.  If the flame be continued, a red
                         incrustation is formed and finally a bead of
                         pure silver remains surrounded by a small
                         slag.

  (4) in forceps. —­

  (5) in borax.  The residual slag obtained on the charcoal
                         gives an iron and copper reaction.

  (6) in mic. salt.  As in borax.

  (7) with carb. soda.  The silver is reduced and the antimony
                         passes off in dense fumes.  The fused alkali
                         gives the sulphur reaction on silver.

  (8) Special reactions. —­

* * * * *

Mineral.  Pyargyrite

Formula. [,Ag]^{3}[,,,Sb].

Behavior
  (1) in glass-bulb.  Sometimes decrepitates, fuses readily, and,
                         when strongly heated, gives a red sublimate
                         of SbS^{3}.

  (2) in open tube.  As in the preceding.

  (3) on charcoal.  Fuses with much spirting and covers the
                         charcoal with antimonial fumes.  When the
                         residual AgS is heated for some time in the
                         oxidizing flame, a bead of pure silver is
                         obtained.

  (4) in forceps. —­

  (5) in borax. —­

  (6) in mic. salt. —­

  (7) with carb. soda.  As the preceding.

  (8) Special reactions. —­

* * * * *

Mineral.  Proustite

Formula. [,Ag]^{3}[,,,As].

Behavior

  (1) in glass-bulb.  Fuses and at a low red heat affords a small
                         sublimate of AsS^{3}.

  (2) in open tube.  Gradually heated it gives off AsO^{3} and
                         SO^{2}.  Sometimes also antimony fumes.

  (3) on charcoal.  As the preceding, except that a large
                         quantity of AsO^{3} and but little SbO^{3}
                         are given off.