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.

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