A System of Instruction in the Practical Use of the Blowpipe Part 9

in the reducing flame.

Treated alone on platinum wire, the gla.s.s becomes of a bottle-green color (F^{3}O^{4}), and if touched with tin, it becomes of a pale sea-green. On charcoal with tin, it a.s.sumes at first a bottle-green color, which by continued blowing changes to a sea-green (FeO).

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

With a certain amount of oxide, the gla.s.s is of a yellowish-red color, which on cooling changes to yellow, then green, and finally becomes colorless. With a large addition of oxide, the color is, when warm, dark red, and pa.s.ses, while cooling, into brownish-red, dark green, and finally brownish-red. During the cooling process, the colors change more rapidly than with borax.

in the reducing flame.

With a small proportion of oxide there is no reaction. With a larger amount the bead is red, while warm, and becomes on cooling successively yellow, green, and russet. With the addition of tin the gla.s.s becomes, during cooling, first green and then colorless.

6. Oxide of Cobalt, CoO.

Behavior with Borax on Platinum wire

in the oxidizing flame:

Colors the gla.s.s of an intense smalt blue both whilst hot and when cold. When much oxide is present, the color is so deep as to appear black.

in the reducing flame:

As in the oxidizing flame.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

As with borax, but less intensively colored. During cooling the color becomes somewhat paler.

in the reducing flame.

As in the oxidizing flames.

7. Oxide of Nickel, NiO.

Behavior with Borax on Platinum wire

in the oxidizing flame.

Colors intensely. A small amount of oxide affords a gla.s.s which, while warm, is violet, and becomes of a pale reddish-brown on cooling. A larger addition produces a dark violet color in the warm and reddish-brown in the cold bead.

in the reducing flame.

The oxide is reduced and the metallic particles give the bead a turbid grey appearance. If the blast be continued the metallic particles fall together without fusing, and the gla.s.s becomes colorless. This reaction is readily obtained with tin upon charcoal, and the reduced nickel fuses to a bead with the tin.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

Dissolves into a reddish gla.s.s which becomes yellow on cooling.

With a large addition of the oxide, the gla.s.s is brownish while hot, and orange when cold.

in the reducing flame.

On platinum wire the nickeliferous bead undergoes no change.

Treated with tin upon charcoal, it becomes at first opaque and grey, and after long continued blowing the reduced nickel forms a bead, and the gla.s.s remains colorless.

8. Oxide of Zinc, ZnO.

Behavior with Borax on Platinum wire

in the oxidizing flame.

Dissolves easily into a clear colorless gla.s.s, which, when much oxide is present, may be rendered opaque and flocculent by an intermittent flame, and becomes so spontaneously with a still larger addition. When a considerable quant.i.ty is dissolved, a gla.s.s is obtained which is pale yellow, while hot, and colorless when cold.

in the reducing flame.

On platinum wire the saturated gla.s.s becomes at first opaque and grey, but by a sustained blast is again rendered clear. On charcoal the oxide is gradually reduced; the metal is volatilized and in crusts the charcoal with oxide.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

As with borax.

in the reducing flame.

As with borax.

9. Oxide of Cadmium, CdO.

Behavior with Borax on Platinum wire

in the oxidizing flame.

When in very large proportion, dissolves to a clear yellow gla.s.s, which becomes nearly colorless on cooling. When the oxide is present in any considerable quant.i.ty, the gla.s.s can be rendered opaque with an intermittent flame, and, with a larger addition, it becomes so spontaneously on cooling.

in the reducing flame.