A System of Instruction in the Practical Use of the Blowpipe Part 12

As in the oxidizing flame.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

As in borax.

in the reducing flame.

As in borax.

23. Oxide of Gold, Au^{2}O^{3}.

Behavior with Borax on Platinum wire

in the oxidizing flame.

Is reduced without being dissolved and can be collected into a bead on charcoal.

in the reducing flame.

As in the oxidizing flame.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

As in borax.

in the reducing flame.

As in borax.

24. t.i.tanic Acid, TiO^{2}

Behavior with Borax on Platinum wire

in the oxidizing flame.

Dissolves readily to a clear gla.s.s which, when but little acid is present, is colorless, but when in larger proportion, yellow, and, on cooling, colorless. When sufficiently saturated, it may be rendered opaque with an intermittent flame, and with a still larger addition of the acid becomes so spontaneously on cooling.

in the reducing flame.

In small proportion, it renders the gla.s.s yellow in larger quant.i.ty dark-yellow or brown. A saturated bead a.s.sumes a blue enamel-like appearance under an intermittent flame.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

Dissolves readily to a clear gla.s.s, which, when sufficiently saturated, is yellow white hot, and becomes colorless on cooling.

in the reducing flame.

The gla.s.s obtained in the oxidizing glame becomes yellow in the hot state, but on cooling a.s.sumes a beautiful violet color. If too saturated, this color is so deep as to appear opaque, but is not enameline. If the t.i.tanic acid contains iron, the gla.s.s becomes on cooling of a brownish-yellow or red color. The addition of tin neutralizes the iron, and the gla.s.s then becomes violet.

25. Tantalic Acid, TaO^{3}.

Behavior with Borax on Platinum wire

in the oxidizing flame.

Dissolves readily to a clear colorless gla.s.s, which, when sufficiently saturated, may be rendered opaque with an intermittent flame, and with a larger addition of the acid becomes spontaneously enameline on cooling.

in the reducing flame.

As in the oxidizing flame.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

Dissolves readily to a clear gla.s.s, which, when it contains a large proportion of the acid, is yellow while warm, but becomes colorless on cooling.

in the reducing flame.

The gla.s.s obtained in the oxidizing flame undergoes no change, nor does it, according to _H. Rose_, alter by the addition of sulphate of iron.

26. Niobic Acid, Ni^{2}O{3}

Behavior with Borax on Platinum wire

in the oxidizing flame.

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

in the reducing flame.

The gla.s.s 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.