oxide is reduced with intumescence to
the metallic state, and the bead becomes clear again. The addition of
tin promotes the reduction.

_Microcosmic Salt_ dissolves oxide of bismuth upon platinum wire, in
the flame of oxidation, to a yellow bead, which becomes colorless
after cooling. By the addition of more oxide, the bead is
yellowish-brown while hot, and colorless after cooling, but not quite
transparent. This bead becomes enamelled when heated by the
intermittent flame; also, by the addition of still more of the oxide,
after it is cooled.

Upon charcoal, in the flame of reduction, and particularly with the
addition of tin, the bead is colorless and transparent while hot, but
while cooling becomes of a dark-gray color and opaque.

Oxide of bismuth is reduced, by fusion with carbonate of soda, as well
in the oxidating as in the reducing flame, instantly to metallic
bismuth.

As the above mentioned higher oxides of bismuth are converted by
ignition into oxide of the metal and free oxygen, they have the same
behavior before the blowpipe.

As bismuth occurs mostly in the metallic form, it is necessary to know
how to distinguish it from metals similar to it. Its brittleness
distinguishes it from lead, zinc and tin, as they are readily
flattened by a stroke of the hammer, while bismuth is broken to
pieces. Bismuth, in this latter respect, might perhaps be mistaken
for antimony or tellurium; but, by the following examination, it is
easy to separate bismuth from antimony or tellurium.

1. Neither bismuth nor antimony sublimates when heated in a glass tube
closed at one end. At a temperature which is about to fuse the glass,
tellurium yields a small quantity of a white vapor (some tellurium is
oxidized to tellurous acid by the oxygen of the air in the tube).
After that, a grey metallic sublimate settles on the sides of the
tube.

2. Heated in an open tube, antimony yields a white vapor, which coats
the inside of the glass tube, and can be driven by heat from one part
of the tube to another without leaving a residue. The metallic globule
is covered with a considerable quantity of fused oxide. Tellurium
produces, under the same circumstances, an intense vapor, and deposits
on the glass a white powder, which melts by heat into globules that
run over the glass. The metallic globules are covered by fused,
transparent, and nearly colorless oxide, which becomes white while
cooling. By a high temperature, and with little a