flame of oxidation easily to a
clear bead, which is yellow while hot, and colorless when cold. The
bead becomes, by the addition of more oxide, enamelled, while cooling.
If the bead is heated with the intermittent flame, it is milk-white
when cold. When heated in the flame of reduction upon platinum wire,
the bead at first appears opaque, and of a greyish color, but becomes
clear again after a continued blast.

When heated upon charcoal in the reduction flame, it is reduced to a
metal; but, at the same moment, is volatilized, and sublimes as oxide
of zinc upon the charcoal, about one line's distance from the assay.
This is likewise the case with the microcosmic salt, except that it is
more easily volatilized in the reduction flame.

Carbonate of soda does not dissolve the oxide of zinc in the flame of
oxidation. In the reduction flame and upon charcoal, the oxide of zinc
is reduced to the metallic state, and is volatilized with a white
vapor of the zinc oxide, which sublimes on the charcoal and exhibits a
yellow color while hot, and which changes to white when cold. By a
strong heat the reduced zinc burns with a white flame.

Moistened with a solution of cobalt oxide, and heated strongly in the
flame of oxidation, zinc oxide becomes of a yellowish-green color
while hot, and changes to a beautiful green color when cold.

(_b._) _Cadmium_ (Cd).--This is one of the rare metals. It occurs in
combination with sulphur in _greenockite_, and in some ores of zinc.
It was detected first in the year 1818, and presents itself as a
tin-white metal of great lustre, and susceptible of a fine polish. It
has a fibrous structure, crystallizes easily in regular octahedrons,
presenting often the peculiar arborescent appearance of the fern. It
is soft, but harder and more tenacious than tin; it can be bent,
filed, and easily cut: it imparts to paper a color like that of lead.
It is very malleable and ductile, and can be hammered into thin
leaves. It is easily fused, and melts before it glows (450 deg.). At a
temperature not much over the boiling point of mercury, it begins to
boil, and distills, the vapor of the metal possessing no peculiar
odor. It is unalterable in the air for a long time, but at length it
tarnishes and presents a greyish-white, half metallic color. This
metal easily takes fire when heated in the air, and burns with a
brownish-yellow vapor, while it deposits a yellow sublimate upon
surrounding bodies. It is easily sol