dily before the Bp. on Ch. and burns with pale yellowish flame,
emitting gray-white fumes having garlic odor.

~Orpiment~, As_{2}S_{3}, As . 61, S . 39.--

H = 1.5-2.0, G = 3.4-3.5.

Lemon-yellow in color and resinous or pearly lustre. Sectile. Before the
Bp. on Ch. behaves like realgar, but in an ignition tube it gives a dark
yellow sublimate which is transparent.

ORES OF BISMUTH

~Native Bismuth, Bi.~--This contains traces of As, Te, and S.

H = 2.0-2.5, G = 9.7-9.83. Color, silver-white, slightly tinged with
red. Metallic lustre. Brittle when cold, but may be laminated when hot.
Before the Bp. on Ch. behaves like pure Bi.

~Bismuthite~, Bi_{2}O_{3} . 90, CO_{2} . 7, H_{2}O . 3,--

H = 4.0-4.5, G = 6.9-7.8.

Usually of a white or light greenish color and vitreous lustre, in
acicular crystallizations. In an ignition tube decrepitates, yielding
water and turning gray. Before the Bp. on Ch. it fuses easily and is
reduced to metallic globule, coating the Ch. with Bi_{2}O_{3}. With
Na_{2}CO_{3} it occasionally gives the sulphur reaction.

ORES OF CHROMIUM

~Chromic Iron Ore~, FeO . 32, Cr_{2}O_{3} . 68.--Al_{2}O_{3}, Fe_{2}O_{3},
MnO, and MgO are commonly present. H = 5.5, G = 4.32-4.57. Occurs
usually massive. Color, iron-black to brownish black. In many varieties
strongly magnetic. Lustre, shining and somewhat metallic. Heated in an
ignition tube, remains unchanged. Infusible before the Bp. on Ch.
Before the Bp. on Ch. with Na_{2}CO_{3} and KCN yields metallic iron. In
borax bead it slowly dissolves to a clear transparent glass, which is a
beautiful green when cool.

ORES OF COBALT

~Smaltite~, Co(Fe, Ni) As_{2}, Co . 28, As . 72.--H = 5.5, G = 6.37-7.30.
Color, tin-white or steel-gray. Lustre, metallic. When heated to redness
in an ignition tube it yields a sublimate of metallic arsenic. Before
the Bp. on Ch. it fuses readily, with emission of arsenical fumes, to a
grayish black magnetic globule. This globule may be examined for iron,
cobalt, and nickel with the borax bead.

~Cobaltite~, CoS_{2} + CoAs_{2}, Co . 36, As . 45, S . 19.--H = 5.5, G =
6.0-6.3. Color, silver-white tinged with red. Metallic lustre. Before
the Bp. on Ch. fuses easily, with emission of copious arsenical fumes,
to a gray magnetic globule. Remains unchanged in the ignition tube.

~Linnaeite~, (Co, Ni)_{3}S_{4}, (Co, Ni)58, S . 42.--H = 5.5, G = 4.8-5.0.
Color, bright steel-gray, sometimes reddish. Lustre, m