422 
ELEMENTARY CHEMICAL MICROSCOPY 
ARSENITES. 
a. With Silver Nitrate. See Arsenic, page 397. 
BORATES. 
a. With Ammonium Fluoride in Dilute Hydrochloric Acid Solu¬ 
tion. Add to the drop on a celluloid slip NaCl, or BaCE, then 
the reagent, then a trace of HCl. See Sodium, page 325, 
Precautions. Silicon, titanium and zirconium must be absent. 
The test drop must be moderately concentrated. 
h. Test with a Turmeric Viscose Silk Fiber. See page 309. 
BROMIDES. 
a. Staining Starch Yellow. 
To a drop of the solution to be tested add a trace of dilute 
sulphuric acid, warm very gently. Cool. Add a very little potato 
starch, just enough to give a few granules in the center of the 
drop. Introduce at the center of the drop a small crystal of 
ammonium persulphate. Bromine is set free and colors the 
starch granules yellow. If iodides are present the starch will 
be colored blue or violet. 
Too long and too high heating will result in the loss of hydro- 
bromic acid. 
If too much sulphuric acid or too much persulphate is added 
the starch granules will be destroyed. 
The preparation must be cool when the starch is added, other¬ 
wise the granules will be destroyed. 
The preparation must be examined at once, otherwise the 
yellow color will have disappeared. 
h. Silver bromide (and silver chloride) is soluble in ammonium 
hydroxide; silver iodide is not. 
CARBONATES. 
a. Characterized by EJfervescence with hydrochloric or sul¬ 
phuric acid. Gas bubbles visible in gelatin. See page 311. 
Cyanates give a similar reaction, carbon dioxide being formed by 
the reaction between cyanate and acid. 
b. In Solutions of Carbonates, Lead Acetate produces charac¬ 
teristic crystals of lead carbonate, in the form of acicular 
