Qualitative Tests. 69 
bules. (Gold-leaf is whitened by the slightest trace of 
vapor of mercury.) 
IN THE WET WAY. 
1. A piece of bright metallic copper is coated with 
a precipitate of metallic Hg, upon insertion in a solu- 
tion of Hg. 
2. SnCl: precipitates first white Hg:Cl: and then 
gray Hg. 
To distinguish between mercurous and mercuric 
compounds HCl precipitates white Hg:Cl2, soluble in 
aqua regia, HNOs, and NH:Cl, and blackened by NH: 
OH, from mercurous compounds. No precipitate on ad- 
dition of HCl to mercuric compounds. 
MOLYBDENUM, Mo. 
WITH THE BLOWPIPE. 
On Coal.—O. F. A coat yellowish hot, white cold; 
crystalline near assay. 
R. F. The coat is turned in part deep blue, in part 
dark copper-red. 
Flame.—Yellowish green. 
With Borax.—O. F. Yellow hot, colorless cold. 
R. F. Brown to black and opaque. 
With S. Ph.—O. F. Yellowish green hot, colorless 
cold. (Crushed between damp unglazed paper becomes 
red, brown, purple, or blue, according to amount pres- 
ent.) 
R. F. Emerald-green. 
Dilute (44,.) HCl Solutions.—If insoluble, the sub- 
stance may first be fused with S. Ph. in O. F. Then. 
if dissolved in the acid and heated with metallic tin, 
zinc, or copper, the solutions will be successively blue, 
green, and brown. If the S. Ph. bead has been treated 
in R. F. the solution will become brown. 
