Behavior with Borax on Platinum wire

    in the oxidizing flame.

Dissolves readily to a clear glass which with a small amount of the oxide is yellow, while warm, and becomes colorless on cooling.  With a larger addition, the glass is, in the hot state, of a deep orange color, which changes to yellow and finally becomes opaline in process of cooling.

    in the reducing flame.

A glass becomes at first grey and turbid, then begins to effervesce, which action continues during the reduction of the oxide, and it finally becomes perfectly clear.  If tin be added, the glass becomes at first grey from the reduced bismuth, but, when the metal is collected into a bead, the glass is again clear and colorless.

  Behavior with Mic.  Salt on Platinum wire

    in the oxidizing flame.

Dissolves in small quantity to a clear colorless glass.  A larger addition affords a glass which, while warm, is yellow, and becomes colorless on cooling.  When in sufficient proportion the glass may be rendered opaque under an intermittent flame, and a still larger addition of oxide renders the bead spontaneously opaque on cooling.

    in the reducing flame.

      On charcoal, and especially with the addition of tin, the glass
      remains colorless and clear, while warm, but becomes on cooling
      of a dark grey color and opaque.

* * * * *

13.  Oxide of Uranium, U^{2}O^{3}.

  Behavior with Borax on Platinum wire

    in the oxidizing flame.

Behaves similarly to oxide of iron, with the exception that the color of the former is somewhat paler.  When sufficiently saturated, the glass may be rendered of an opaque yellow by an intermittent flame.

    in the reducing flame.

Affords the same color as the oxide of iron.  The green glass obtained in this flame, if sufficiently saturated, can be rendered black by an intermittent flame, but it has under these circumstances no enameline appearance.  On charcoal, with the addition of tin, the glass takes a dark green color.

  Behavior with Mic.  Salt on Platinum wire

    in the oxidizing flame.

      Dissolves to a clear yellow glass, which assumes a
      yellowish-green color on cooling.

    in the reducing flame.

      The glass assumes a beautiful green color, which becomes more
      brilliant as the bead cools.  The addition of tin upon charcoal
      produces no further change.

* * * * *

14.  Oxide of Copper, CuO.

  Behavior with Borax on Platinum wire

    in the oxidizing flame.

Produces an intense coloration.  If in small quantity, the glass is green, while warm, and becomes blue on cooling.  If in large proportion, the green color is so intense as to appear black.  When cool, this becomes paler, and changes to a greenish blue.

    in the reducing flame.