320 
ELEMENTARY CHEMICAL MICROSCOPY 
B. ANISOTROPIC. 
Hexagonal. — Nitrate (pseudo 0); normal phos¬ 
phate; potassium-sodium molybdate; silico- 
fluorided 
Tetragonal. 
Orthorhombic. — lodate; nitrite; potassium-sodium 
tartrate; normal tartrate; primary phos¬ 
phate. 
Monoclinic. —^Acetate; secondary arsenate; borates, 
tetra and meta; carbonate; primary carbon¬ 
ate; chromate; ferrocyanide;^ oxalate, ferric- 
sodium; secondary phosphate; ammonium- 
sodium acid phosphate; sulphate; primary 
sulphate; thiosulphate; zinc-sodium sul¬ 
phate. 
Triclinic. — Bichromate; bitartrate; primary oxa¬ 
late. 
DETECTION. 
A. — By means of Uranyl Acetate. 
Apply test by Method IV, page 303. 
Sodium yields with uranyl acetate small faintly yellow tetra- 
hedra, appearing black by transmitted light. The compound 
formed probably has the formula NaC2H302 • U02(C2H302)2. 
The crystals are isotropic belonging to the isometric system. 
Potassium, rubidium, cesium and ammonium yield long 
needles or slender prisms of the tetragonal system of greater 
solubility than the sodium compound and therefore not appear¬ 
ing until the preparation has evaporated almost to complete 
dryness. 
Because of the high solubility of ammonium uranyl acetate, 
SchoorP has suggested its use for detecting sodium instead of 
simple uranyl acetate. The test thus made is more sensitive, 
but lacks the convenience of the method given above in that no 
1 Na2SiF6 is said to be pseudohexagonal. 
2 Na4Fe(CN)6 • 12 H2O is pseudotetragonal. 
3 Lenz u. Schoorl, Zeit. anal. Chem., 60 (1911), 263. 
