the carbon, as a white metallic powder,
which is infusible, and has a greater attraction for the magnet than
iron.

_Sesquioxide of Nickel_ (Ni^{2}O^{3}).--It is in the form of a black
powder, and does not combine with other substances, unless it is
reduced to the protoxide. It exhibits before the blowpipe the same
behavior as the protoxide.

GROUP SIXTH.--ZINC, CADMIUM, ANTIMONY, TELLURIUM.

The substances of this group can be reduced upon charcoal by fusion
with carbonate of soda, but the reduced metals are volatilized, and
cover the charcoal with sublimates.

(_a._) _Zinc_ (Zn).--This metal is found in considerable abundance,
but never occurs in the pure metallic state, but in combination with
other substances, chiefly as sulphide in zinc blende, as carbonate in
calamine, and as the silicate in the kieselzinc ore; also, with
sulphuric acid, the "vitriol of zinc."

Zinc is of a bluish-white color and metallic lustre, is crystalline
and brittle when heated 400 deg.F., but malleable and ductile between 200 deg.
and 300 deg.. It will not oxidize in dry air, but tarnishes if exposed to
air containing moisture, first becomes grey, and then passes into the
white carbonate. It decomposes in water at a glowing heat. It is
dissolved by diluted acids, while hydrogen is eliminated. It melts at
about 775 deg., and distills when exposed to a white heat in a close
vessel. When heated over 1000 deg. in the open air, it takes fire, and
burns with a bluish-white light, and with a thick white smoke of oxide
of zinc.

_Oxide of Zinc_ (ZnO).--In the pure state, oxide of zinc is a white
powder, infusible, and not volatile. It is readily soluble in acids
after being heated strongly. Its soluble neutral salts, when dissolved
in water, change blue litmus paper to red. Its salts, with organic
acids, are decomposed by ignition, and the carbonate of zinc remains.

The oxide of zinc turns yellow by being ignited in the oxidation
flame, but it is only visible by daylight; this color changes to white
when cold. It does not melt, but produces a strong light, and it is
not volatile.

It disappears gradually in the flame of reduction, while a white smoke
sublimates upon the charcoal. This sublimate is yellow while hot, but
changes to white when cold. The cause of this is, that the oxide is
reduced, is volatilized, and re-oxidized, by going through the
external flame in the form of a metallic vapor.

Borax dissolves oxide of zinc in the