A System of Instruction in the Practical Use of the Blowpipe Part 10

Upon charcoal ebullition takes place and the oxide is reduced.

The metallic cadmium is volatilized and incrusts the charcoal with its characteristic deep yellow oxide.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

When in very large proportion dissolves to a clear gla.s.s, having a yellow tinge, while hot, which disappears on cooling, and when perfectly saturated, becomes milk-white.

in the reducing flame.

On charcoal the oxide is slowly and imperfectly reduced. The reduced metal forms the characteristic incrustation on the charcoal, but the is thin and does not exhibit its color clearly until quite cold. The addition of tin hastens the reaction.

10. Oxide of Lead, PbO.

Behavior with Borax on Platinum wire

in the oxidizing flame.

Dissolves readily to a clear yellow gla.s.s, which loses its color upon cooling, and when containing much oxide can be rendered dull under an intermittent flame. With a still larger addition of oxide it becomes opaline yellow on cooling.

in the reducing flame.

The plumbiferous gla.s.s spreads out on charcoal, becomes turbid, bubbles up, until the whole of the oxide is reduced, when it again becomes clear. It is, however, difficult to bring the lead together into a bead.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

As with borax, but a larger addition of oxide, required to produce a yellow color in the warm bead.

in the reducing flame.

On charcoal the plumbiferous gla.s.s becomes grey and dull. With an over dose of oxide a part is volatilized and forms an incrustation on the charcoal beyond the bead. The addition of tin does not render the gla.s.s opaque, but somewhat more dull and grey than in its absence.

11. Oxide of Tin, SnO^{2}.

Behavior with Borax on Platinum wire

in the oxidizing flame.

In small quant.i.ty dissolves slowly into a clear colorless gla.s.s, which, when cold, remains clear, and cannot be rendered opaque with an intermittent flame. If a saturated bead, which has been allowed to cool, be reheated to incipient redness, it loses its rounded form and exhibits imperfect crystallization.

in the reducing flame.

A gla.s.s containing but little oxide undergoes no change. If much of the latter be present, a part may be reduced upon charcoal.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

In small quant.i.ty dissolves very slowly to a colorless gla.s.s, which remains clear on cooling.

in the reducing flame.

The gla.s.s undergoes no change, either on charcoal or platinum wire.

12. Oxide of Bis.m.u.th, BiO^{3}.

Behavior with Borax on Platinum wire

in the oxidizing flame.

Dissolves readily to a clear gla.s.s which with a small amount of the oxide is yellow, while warm, and becomes colorless on cooling. With a larger addition, the gla.s.s is, in the hot state, of a deep orange color, which changes to yellow and finally becomes opaline in process of cooling.

in the reducing flame.

A gla.s.s becomes at first grey and turbid, then begins to effervesce, which action continues during the reduction of the oxide, and it finally becomes perfectly clear. If tin be added, the gla.s.s becomes at first grey from the reduced bis.m.u.th, but, when the metal is collected into a bead, the gla.s.s is again clear and colorless.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

Dissolves in small quant.i.ty to a clear colorless gla.s.s. A larger addition affords a gla.s.s which, while warm, is yellow, and becomes colorless on cooling. When in sufficient proportion the gla.s.s may be rendered opaque under an intermittent flame, and a still larger addition of oxide renders the bead spontaneously opaque on cooling.

in the reducing flame.

On charcoal, and especially with the addition of tin, the gla.s.s 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 gla.s.s 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 gla.s.s obtained in this flame, if sufficiently saturated, can be rendered black by an intermittent flame, but it has under these circ.u.mstances no enameline appearance. On charcoal, with the addition of tin, the gla.s.s takes a dark green color.