88 CHEMICAL PROPERTIES OF MINERALS. 
required, and sometimes the use of soda. With borax iron 
gives a bead with the oxidizing flame which is yellow while 
hot, but colorless on cooling, and which in the reducing flame 
becomes bottle green. 
Cobalt.—Minerals containing cobalt afford, with borax, a 
beautiful blue bead. If sulphur or arsenic is present it should 
be first roasted off on charcoal. 
Nickel.—In the oxidizing flame with borax, the bead is violet 
when hot, and red-brown on cooling. In the reducing flame 
the glass becomes gray and turbid from the separation of metal- 
lic nickel, and on long blowing, colorless. The reaction is ob- 
scured by the presence of cobalt, iron, and copper. | 
Manganese.—With borax in the oxidizing flame, the bead is 
a deep violet-red, and almost black if too much of the mineral 
is used. To see the color examine by transmitted light. With 
soda in the same flame the opaque bead is bluish green. 
Chromium.—With borax, both in the oxidizing and reducing 
flame, the bead is bright emerald green. 
Titanium.—Titanium oxide with salt of phosphorus on 
platinum wire in O.F. dissolves to a clear glass, which, if 
much is present, becomes yellow while hot and colorless on 
cooling; but in R.F. the hot globule obtained in O.F. reddens 
and assumes finally a beautiful violet color. On charcoal with 
tin the glass becomes violet if there is not too much iron 
present. 
Zinc.—Zine and some of its compounds when heated cover 
the charcoal with zine oxide, which is yellow while hot, but 
white on cooling ; and this coating, if wet with cobalt solution 
and tren heated, assumes a fine. yellowish-green color which 
is most distinct when cold. 
Lead, copper, tin, silver, when characterizing a mineral, give 
with soda in the reducing flame minute metallic globules, which 
are malleable, or may be cut with a knife; they can be distin- 
guished by their well-known physical properties. When two 
or more of these metals occur together, or iron is also present, 
the globules consist usually of an alloy of the metals. 
Lead.—When the mineral is treated with soda on charcoal 
in the oxidizing flame, the yellow oxide coats the charcoal 
around the assay. 
Copper.—The flame is colored, in most cases, bright green. 
With borax or salt of phosphorus in the reducing flame the 
bead is red. In the oxidizing flame the bead is green when 
hot and becomes blue or greenish blue on cooling. 
Mercury.—Heated in the closed tube with soda, a sublimate 
of metallic mercury covers the inside of the tube. 
