• MICROCHEMICAL REACTIONS OF MANGANESE 407 
This test is excellent when pure manganous salts are being 
dealt with, but is seriously affected by much alkali and ammonium 
salts or by the presence of those elements readily precipitated as 
oxalate, for example, the elements of Group VIII of the Periodic 
System, or those of Group II. 
Free mineral acids seriously interfere. 
With solutions highly concentrated with respect to manganese 
no reaction will be obtained nor will satisfactory results follow 
the use of too dilute test drops. 
Silver, lead, mercurous and stannous salts should be absent. 
EXPERIMENTS. 
a. Test as above MnS04. Then try the addition of a drop of H2C2O4 to a test 
drop by Method 7, page 299. 
h. Try effects of free acids upon the test. 
c. Test mixtures of MnS04 with members of Group VIII. 
B. By Means of Potassium Chromate. 
Apply reagent to test drop by Method III, page 300. 
Sheaves of yellowish brown, acicular, strongly pleochroic 
crystals separate from neutral or feebly acid solutions; but from 
drops containing a trace of free nitric acid stout dendritic masses 
and clusters of yellowish brown prisms are obtained. The test 
drop should be moderately concentrated. 
Nitric acid greatly slows down the reaction and if present in 
more than traces prevents the formation of crystals. The other 
mineral acids behave in a similar fashion. 
With pure manganous salts this test is excellent, but is of 
little value in the presence of silver, lead, mercury or in fact any 
element forming a difficultly soluble chromate. 
See Silver, Method B, page 380; Mercury, Method B, page 
367- 
Potassium bichromate applied as above gives no crystalline 
precipitate. 
EXPERIMENTS. 
a. . Test a drop of MnS04 with K2Cr04; with K2Cr207. 
b. Repeat the test, previously acidifying with HNOs; with HCl; with HC2H3O2. 
c. Repeat in the presence of Ag, of Pb. 
