MICROCHEMICAL REACTIONS OF THE COMMON ACIDS 427 
with a crystal of morphine sulphate as described under iodates, 
page 425. 
OXALATES. 
a. With Strontium Acetate. See Calcium, page 337; Stron¬ 
tium, page 343. 
h. With Silver Nitrate or Lead Nitrate. See Calcium, page 337. 
PHOSPHATES. 
a. To the drop to he tested, add a drop of Nitric Acid. Then 
apply a drop of Ammonium Molybdate by Method I, page 299. 
Warm gently. Phosphates yield a yellow precipitate at first 
appearing amorphous under the microscope unless a magnifica¬ 
tion of over 200 is employed. Later light yellow almost trans¬ 
parent, octahedra-like crystals are formed; especially in the pres¬ 
ence of sodium salts. A similiar reaction will be obtained if 
silicomolybdates or arseno-molybdates are formed. 
This reaction is of value if arsenic and soluble silicates are 
absent and as indicating whether much or little phosphate is 
present. If a heavy precipitate is obtained, apply test h. 
h. To the Ammoniacal Solution add Ammonium Chloride and 
Magnesium Acetate, proceeding as described under Magnesium, 
page 351. Arsenates must be absent. 
Note. — Phosphates frequently interfere with the detection 
of certain bases and must be removed before reliable reactions 
can, be obtained; their removal may be accomplished by means 
of tin in acid solution. Acidify with nitric acid, add a few tiny 
bits of pure tin-foil and as soon as the reaction has ceased, heat 
to boiling. Cool and extract the material with dilute nitric acid. 
SILICATES. 
a. Treat the material upon a celluloid object slide with ammo¬ 
nium fluoride, sodium chloride and sulphuric acid. Sodium silico- 
fluoride is formed. See Sodium, page 324. Boron, zirconium 
and titanium must be absent. 
SULPHATES. 
a. To the drop add a trace of Nitric Acid, then a drop 
oj Calcium Acetate by Method I, page 299. Characteristic 
