blue when the heat is increased.

~Smithsonite~,

Zn . CO_{3}, ZnO . 64.8, CO_{2} . 35.2.--

H = 5, G = 4.30-4.45. Color, gray, yellow, brown, and green. Lustre,
vitreous, pearly. Heated in an ignition tube CO_{2} is evolved, residue
appearing white. It often contains impurities of Cd, Pb, Fe, Mn, Ca, and
Mg. When these are present the residue in the ignition tube becomes dark
on cooling. Before the Bp. on Ch. with Na_{2}CO_{3} and exposed to the
R. F. it is decomposed. It gives the characteristic reaction for zinc
with Co(NO_{3})_{2}.

~Zincite~, ZnO, Zn . 80.3, O . 19.7--

H = 4.0-4.5, G = 5.43-5.70.

Color, blood-red. Lustre, brilliant, subadamantine. Before the Bp. on
Ch. infusible. Before the Bp. on Ch. with Na_{2}CO_{3} gives coating of
zinc oxide. Gives characteristic reaction with Co(NO_{3})_{2}. It
frequently contains a small quantity of Mn_{2}O_{3}, which may be
detected in the borax bead.

~Sphalerite~, ZnS, Zn . 67, S . 33.--

H = 3.5-4.0, G = 3.9-4.1.

Color, yellow to black. Lustre, resinous, brilliant, and sometimes
submetallic. Heated in an ignition tube sometimes decrepitates. Before
the Bp. on Ch. infusible. Before the Bp. on Ch. with Na_{2}CO_{3} easily
reduced. With Co(NO_{3})_{2} gives the characteristic reaction. It
frequently contains small quantities of Cd, Hg, Sn, Pb, Au, Ag, etc.

I

TABLE OF COLORS OF COATINGS ON CHARCOAL

--------------------------------------------------
Element | Color Hot | Color Cold |
---------|------------------------|---------------|
Antimony | (Rather volatile) | White |
| | |
Arsenic | (Very volatile) | White |
| | |
Bismuth | Orange-Yellow | Lemon-Yellow |
| | |
Cadmium | Brownish Yellow | Reddish Brown |
| | |
Lead | Lemon-Yellow (volatile)| Lemon-Yellow |
| | |
Silver | Dark Red | Dark Red |
| | |
Tin | Faint Yellow | White |
| | |
Zinc | Yellow | White |
--------------------------------------------------

II

TABLE OF FLAME COLORATIONS

-----------------------