MICROCHEMICAL REACTIONS OF POTASSIUM 
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sodium manganate/ so as to impart a distinct green, then add 
a tiny drop of hydrochloric acid, thus converting the manganate 
into permanganate. The perchloric acid is then caused to flow 
in. The crystals of potassium perchlorate which separate have 
the same form as before, but are a beautiful deep rose color, the 
color intensity varying with the amount of permanganate present. 
In a few moments the liquid is completely decolorized, and the 
precipitated crystals deeply colored. Performed in this way the 
test is a most interesting and instructive one. 
The perchlorate reaction is of more value for the detection of 
the acid by means of rubidium chloride and for the removal of 
potassium to prevent interferences with tests for other elements, 
than for the identification of potassium. 
Precautions. 
To obtain truly satisfactory results, careful attention to con¬ 
centrations must be given, for if the solution is too concentrated 
potassium perchlorate is precipitated at once in malformed or 
skeleton crystals; while if too dilute the separation of the solid 
phase is too slow. 
Exposure to alcohol vapor hastens the reaction. 
In the absence of perchloric acid ammonium perchlorate may 
be used. 
EXPERIMENTS. 
a. Try the above reaction with different salts of K. 
b. Introduce NaMn04 into the test drop, and test as above. 
c. Make a mixture of K and Na salts. Treat a drop of a solution of this mate¬ 
rial with HCIO4, evaporate, treat with the reagent again and again evaporate, 
extract the dry residue with alcohol, and test the alcoholic extract for sodium with 
U02(C2H302)2. 
d. Try the action of HCIO4 on members of the magnesium group, and upon 
members of the calcium group. 
AMMONIUM. 
Crystal Forms and Optical Properties of Common Salts 
of Ammonium. 
1 Sodium manganate is employed instead of sodium permanganate because it 
is more stable as a laboratory reagent. 
