requires a very large dose of the acid to render it opaque under
an intermittent flame. With an increased amount of the acid, the
glass is clear and yellow, while warm, but becomes on cooling
turbid, and when quite cold is white.

in the reducing flame.

The glass obtained in the oxidizing flame and which has become
opalescent on cooling, is rendered clear in the reducing flame.
With a larger addition of the acid, it becomes dull, and of a
bluish-grey color on cooling, and a still larger amount of
renders it opaque and bluish grey.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

Dissolves in large quantities to a clear colorless glass.

in the reducing flame.

If the acid be not present in too large a proportion, the glass
remains unchanged. An additional amount of the acid renders it
violet, and a still larger quantity affords a beautiful pure
blue color, similar to that produced by tungstic acid. If to
such a bead some sulphate of iron be added, the glass becomes
blood-red. The addition of peroxide of iron renders the glass
deep yellow while warm, the color becomes paler on cooling.

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