408 ELEMENTARY CHEMICAL MICROSCOPY 



C. Through Fusion with a Mixture of Sodium Carbonate and 

 Potassium Nitrate. 



The fusion should be made in a small platinum cup or 

 upon platinum foil, using the smallest possible amount of the 

 fusing mixture which will react with the unknown. It is always 

 wise to first obtain the hydroxide or oxide and employ this 

 material for the fusion. 



If manganese is present a green color is obtained, due to the 

 formation of manganates of sodium and potassium Na 2 Mn04, 

 K 2 Mn0 4 . 



Iron and chromium mask the reaction. 



EXPERIMENTS. 



a. Test several different Mn compounds by fusing on platinum foil or in a bead 

 on Pt wire. 



D. By Means of Phosphates in Ammoniacal Solution. 



Manganous salts are precipitated as NH4MnPO.i-6 H2O. 

 See Magnesium, Method B, page 350; Nickel, Method B, 

 page 412; Cobalt, Method C, page 414. 



Add to the slightly acidified test drop, ammonium chloride 

 and secondary sodium phosphate, then add ammonium hydroxide 

 by Method /. 



The hemimorphic crystals obtained usually grow somewhat 

 longer than those of magnesium but are otherwise identical. 

 They are proved to be due to manganese by adding hydrogen 

 peroxide which causes them to turn brown. 



E. By Means of Sodium Bismuthate. 



Dissolve the material in concentrated nitric acid and 

 evaporate the solution to dryness. Dissolve in dilute nitric acid, 

 add several small portions of sodium bismuthate, stirring after 

 each addition, allow to stand a short time; a pink or purple color 

 results with a precipitation of brown oxide of manganese. Next 

 add very carefully in tiny fragments just sufficient, no more, sodium 

 thiosulphate to dissolve the precipitate oxide. A colorless milky 

 drop results; add a drop of nitric acid (1:4) and stir thoroughly. 

 Now again add carefully and slowly a very little at a time sodium 



