If not too saturated, the cupriferous glass soon becomes nearly colorless, but immediately on solidifying assumes a red color and becomes opaque.  By long continued blowing on charcoal, the copper in the bead is reduced and separates out as a small metallic bead, leaving the glass colorless.  With the addition of tin, the glass becomes of an opaque dull-red on cooling.

  Behavior with Mic.  Salt on Platinum wire

    in the oxidizing flame.

With an equal proportion of oxide, this salt is not so strongly colored as borax.  A small amount imparts a green color in the warm and a blue in the cold.  With a very large addition of oxide, the glass is opaque in the hot state, and after cooling of a greenish-blue.

    in the reducing flame.

A tolerably saturated glass assumes a dark green color under a good flame, and on cooling becomes of an opaque brick-red, the moment it solidifies.  A glass containing but a small proportion of the oxide becomes equally red and opaque on cooling, if treated with tin upon charcoal.

* * * * *

15.  Oxide of Mercury, HgO.

  Behavior with Borax on Platinum wire

    in the oxidizing flame.

      No reaction.

    in the reducing flame.

      No reaction.

  Behavior with Mic.  Salt on Platinum wire

    in the oxidizing flame.

      No reaction.

    in the reducing flame.

      No reaction.

* * * * *

16.  Oxide of Silver, AgO.

  Behavior with Borax on Platinum wire

    in the oxidizing flame.

The oxide is partly dissolved and partly reduced.  In small quantity, it colors the glass yellow while warm, the color disappearing on cooling.  In larger quantity, the glass is yellow while warm, but during cooling becomes paler to a certain point, and then again deeper.  If reheated slightly, the glass becomes opalescent.

    in the reducing flame.

      On charcoal the argentiferous glass becomes at first grey from
      the reduced metal, but afterwards, when the silver is collected
      into a bead, it becomes clear and colorless.

  Behavior with Mic.  Salt on Platinum wire

    in the oxidizing flame.

      Both the oxide and the metal afford a yellowish glass, which,
      when containing much oxide becomes opaline, exhibiting a yellow
      color by daylight and a red one by artificial light.

    in the reducing flame.

      As in borax.

* * * * *

17.  Oxide of Platinum, PtO^{2}. 18.  Oxide of Palladium, PdO^{2}. 19.  Oxide of Rhodium, R^{2}O^{3}. 20.  Oxide of Iridium, Ir^{2}O^{3}. 21.  Oxide of Ruthenium, Ru^{2}O^{9}. 22.  Oxide of Osmium OsO^{2}.