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.