A System of Instruction in the Practical Use of the Blowpipe Part 8

in the oxidizing flame.

Dissolves into a red or dark yellow gla.s.s (similar to that produced by iron). During cooling, the color diminishes in the intensity and becomes finally yellow. If much oxide be dissolved, an opaque bead may be obtained with an intermittent flame, and a still larger quant.i.ty renders it opaque spontaneously.

in the reducing flame.

The color of the bead becomes paler, so that a bead, which is yellow in the oxidizing flame, is rendered colorless. With a large quant.i.ty of oxide the bead becomes white and crystalline on cooling.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

As with borax. During the process of cooling the color entirely disappears.

in the reducing flame.

Both, when hot and cold, the bead is colorless, by which character oxide of cerium may be distinguished from oxide of iron. The gla.s.s remains clear even when containing a large quant.i.ty of the oxide.

2. Oxide of Lanthanum, LaO.

Behavior with Borax on Platinum wire

in the oxidizing flame.

Dissolves into a colorless gla.s.s, which, when sufficient oxide is present, may be rendered opaque with an intermittent flame, and becomes so spontaneously on cooling, when a still larger amount is dissolved.

in the reducing flame.

As in the oxidizing flame.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

As with borax.

in the reducing flame.

No reaction.

3. Oxide of Didymium, DO.

Behavior with Borax on Platinum wire

in the oxidizing flame:

Dissolves to a clear dark amethystine gla.s.s.

in the reducing flame.

No reaction.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

As with borax.

in the reducing flame.

No reaction.

4. Oxide of Manganese, Mn^{2}O^{3}.

Behavior with Borax on Platinum wire

in the oxidizing flame.

Affords an intense amethyst color, which on cooling becomes violet. A large quant.i.ty of the oxide produces an apparently black bead, which however, if pressed flat, is seen to be transparent.

in the reducing flame.

The colored bead becomes colorless. With a large amount of the oxide, this reaction is best obtained upon charcoal, and is facilitated by the addition of tin foil.

Behavior with Mic. Salt on Platinum wire

in the oxidizing flame.

With a considerable quant.i.ty of oxide an amethyst color is obtained, but never so dark as in borax. With but little oxide a colorless bead is obtained, in which, however, the amethyst-color may be brought out by adding a little nitre.

While the bead is kept fused, it froths and gives off bubbles of gas.

in the reducing flame.

The colored bead immediately loses its color, either on platinum wire or on charcoal. After the reduction the fluid bead remains still.

5. Oxide of Iron, Fe^{2}O^{3}.

Behavior with Borax on Platinum wire

in the oxidizing flame.

With a small proportion of oxide, the gla.s.s is of a yellow color, while warm, and colorless when cold; with a larger proportion, red, while warm, and yellow, when cold; and with a still larger amount, dark-red, while warm, and dark-yellow, when cold.