412 
ELEMENTARY CHEMICAL MICROSCOPY 
salts, such as (NH4)2S04-FeS04 or 2 NH4Cl-FeCl2. Non¬ 
volatile organic acids prevent the precipitation of ferric hydroxide 
and the ferric salts thus remaining in solution will react with 
the glyoxime. 
B. Other Tests for Nickel. 
1. Triple nitrite of lead nickel and potassium K2PbNi(N02)6. 
See Lead, Method C, page 373; Copper, Method B, page 386. 
2. Ammonium nickelous phosphate NH4NiP04 • 6 H2O. See 
Magnesium, Method B, page 350. This salt is isomorphous 
with the magnesium salt. 
Note. — The addition of hydrogen peroxide causes no. change 
in the color of the crystals of ammonium nickel phosphate, but 
will turn those of cobalt brown. 
EXPERIMENTS. 
a. Try the glyoxime reaction on salts of Ni in NH4OH and in acid solution; and 
in different concentrations. 
b. Try test upon Co compounds. 
c. Make a mixture of Ni and Co and test. 
d. Test for Ni in the presence of much Cu. 
Remove the Cu from a drop by means of metallic Zn and test again. Then try 
the detection of Ni in the presence of much Fe. 
e. Apply the phosphate test to a Ni (ous) salt and as soon as the crystals are well 
formed, allow a drop of H2O2 to flow into the drop. Repeat the process with a 
Co salt. 
COBALT. 
Crystal Forms and Optical Properties of Common Salts of 
Cohalt. 
A. ISOTROPIC. 
B. ANISOTROPIC. 
Hexagonal. 
T etr agonal. 
Orthorhombic. — Ammonium-cobalt phosphate; 
purpureo-chloride (pseudotetragonal). 
Monoclinic. —Acetate; chloride; luteo-chloride; 
nitrate; potassium-cobalt sulphate; roseo- 
chloride; sulphate. 
Triclinic. 
