Qualitative Tests. 61 
On Coal, with CuO.—Grind with a drop of H:SQs, 
spread the paste on coal, dry gently in O. F., and treat 
with blue flame, which will be colored greenish blue 
and then azure-blue. 
IN THE WET WAY. 
A; AgNOs precipitates white AgCl, soluble in 
NH.OH. 
CHROMIUM, Cr. 
WITH THE BLOWPIPE. 
With Borax or 8. Ph._—O. F. Reddish hot, fine yel- 
low green cold. 
R. F. In borax, green hot and cold. In S. Ph. red 
hot, green cold. 
With Soda.—O. F. Dark yellow hot, opaque and 
light yellow cold. 
R. F. Opaque and yellowish green cold. 
Interfering Elements. 
Manganese.—The soda bead in O. F. will be bright 
-yellowish green. 
IN THE WET WAY. 
1. NH:OH precipitates bluish green Cr:(OH)s, 
slightly soluble in excess. 
2. From solutions of CrOs lead salts precipitate 
yellow PbCrO., soluble in HNOs and insoluble in acetic 
acid. Difficulty soluble in KOH. 
3. A very delicate test for Cr as CrOs is by means 
of H:O0: (hydrogen peroxide) and ether, giving 2 fine 
blue color. 
COBALT, Co. 
WITH THE BLOWPIPE. 
On Coal, R. F.—The oxide becomes magnetic 
metal. The solution in HCl will be rose-red, but on 
avaporation will be blue. 
With Borax or S. Ph.—Pure blue in either flame. 
