MANGANESE. 155 



By evaporation and crystallization the potassium permangan- 

 ate is obtained in slender, prismatic crystals, of a deep, purple- 

 violet color and a somewhat metallic lustre. The solution in 

 water has a deep purple or, when highly diluted, a pink color. 

 It is a powerful oxidizing agent and an excellent disinfectant, 

 both properties being due to the facility with which a portion of 

 the oxygen is given off to any substance which has affinity 

 for it : 



K 2 Mn 2 8 + 6HC1 + x = 2KC1 -f 2MnCl 2 -f 3H 2 O + x0 5 . 



x represents here any substance capable of combining with 

 oxygen while in solution. 



Analytical reactions. 



1. Ammonium sulphide produces, with manganous salts, a 

 yellowish-pink or flesh-colored precipitate of manganous sul- 

 phide, soluble in acetic and in mineral acids: 



MnS0 4 + (NH 4 ) 2 S = (NH 4 ) 2 SO 4 + MnS. 



2. Ammonium hydrate produces a white precipitate of man- 

 ganous hydrate, which soon darkens by absorption of oxygen. 

 The precipitate is soluble in excess of ammonia. 



MnCl 2 + 2NH 4 HO == 2NH 4 C1 + Mn2HO. 



3. Potassium and sodium hydrates show the same reaction ; 

 the precipitate is insoluble in excess of the alkaline hydrates. 



4. Sodium (or potassium) carbonate produces a precipitate of 

 manganous carbonate : 



MnSO 4 + Na 2 CO 3 = Na 2 SO 4 + MnCO 3 . 



5. Any compound of manganese heated on platinum foil 

 with a mixture of sodium carbonate and nitrate forms a green 

 mass, giving a green solution in water, which turns red on addi- 

 tion of an acid. (See explanation above.) 



6. Manganese compounds fused with borax on a platinum 

 wire give a violet coloration to the borax bead. 



7. Traces of manganese may be detected by boiling with 

 dilute nitric acid and red lead, when the solution acquires a 

 violet color due to the formation of permanganic acid. 



