MICROCHEMICAL REACTIONS OF THE COMMON ACIDS 417 
I. To a drop of the moderately concentrated aqueous solution of the unknown 
apply a drop of concentrated solution of silver nitrate by Method /, page 299 . 
A. No precipitate is produced and no crystalline deposit is ob¬ 
tained until the drop concentrates through spontaneous evapo¬ 
ration. See I. A, below. 
B. A colored precipitate is produced. See I. B, below. 
C. A white or colorless precipitate is produced. See page 418. 
After a few seconds apply a small drop of nitric acid (i : 3) to 
the zone of precipitate. 
1. The precipitate dissolves in whole or in part. If only in 
part, decant the solution and apply a fresh drop of nitric acid 
to the residue, to ascertain if the unknown consists of a mixture 
of both soluble and insoluble silver salts. 
2. The precipitate is unafected. 
n. To another drop of the dilute aqueous solution add a drop of barium 
chloride solution. See page 299 . 
A. No precipitate results. See page 419. 
B. An amorphous, granular or crystalline precipitate is pro¬ 
duced. See page 419. 
1. The precipitate is soluble in whole or in part in nitric acid. 
2. The precipitate is insoluble in nitric acid. 
III. To a drop of the dilute aqueous solution of the unknown material add a 
drop of nitric acid. A granular or amorphous precipitate results. See page 420 . 
I. A. No Precipitate with Silver Nitrate. 
Chlorate. 
Fluoride; silicofluoride.^ 
Nitrate. 
Perchlorate.^ 
Sulphate.^ 
I. B. The Precipitate is Colored {by Reflected Light). 
Arsenate. Red, brown or thick crystals black. 
Arseni te. Yellow. 
Chromate, bichromate. Red, brown or black. 
^ Crystals separate slowly from moderately concentrated solutions or even 
from dilute solutions on long standing. 
