in the oxidizing flame.

Even when in large proportion, dissolves to a clear glass, which
is yellow when warm, but almost entirely loses its color on
cooling. On charcoal, the antimonious acid may be almost
expelled, so that tin produces no further change.

in the reducing flame.

A bead, that has only been treated for a short time in the
oxidizing flame, when submitted to the reducing flame becomes
grey and turbid from the reduced antimony. This soon volatizes
and the glass again becomes clear. The addition of tin renders
the glass ash-grey or black, according to the amount of oxide it
contains.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

Dissolves with ebullition to a glass of a pale yellow color
while warm.

in the reducing flame.

On charcoal, the saturated glass becomes at first dull, but as
soon as the reduced antimony is volatilized, it again becomes
clear. With tin, the glass is at first rendered grey by the
reduced antimony, but by continued blowing is restored to
clearness. Even when the glass contains but little oxide, tin
produces this reaction.

* * * * *

29. Tungstic Acid, WO^{3}.

Behavior with Borax on Platinum wire

in the oxidizing flame.

Dissolves readily to a clear colorless glass. In large
proportion it renders the borax yellow, while warm, and with a
still greater addition the bead may be made opaque with an
intermittent flame. If more be then added, this reaction takes
place spontaneously.

in the reducing flame.

When the oxide is present in small quantity, the glass undergoes
no change. With a larger proportion, the glass is deep yellow
while warm, and yellowish-brown when cold. This reaction takes
place upon charcoal, with a small quantity of the acid. Tin
produces a dark coloration, when the acid is not present in too
great a quantity.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

Dissolves to a clear glass, which, when saturated, is yellow in
the hot state.

in the reducing flame.

The glass is of a pure blue. If the tungstic acid contain iron,
the glass becomes blood-red on cooling, similar to titanic acid.
In this case, tin restores the blue color, o