PROTOCIILOR1DE OF MANGANESE. 531 



oxygen from the air and becomes brown ; collected on a filter 

 and washed, it ends by changing into a blackish brown powder, 

 which is the hydrate of the deutoxide. A similar change is in- 

 stantaneously produced by the action of chlorine- water upon 

 the white hydrate, or by the addition of chloride of lime to a 

 salt of the protoxide of manganese, but then the hydrated pe- 

 roxide is formed. Protoxide of manganese resembles magnesia 

 and protoxide of iron^ in being precipitated by ammonia only 

 in part. 



Its salts are sometimes colourless, but more generally of a 

 pale rose tint, which has been ascribed to a trace of manganic 

 acid. But as the rose tint is not destroyed by sulphuretted 

 hydrogen, it must be considered as a peculiar, although only 

 occasional, character of manganous salts, (p. 152). Solutions of 

 the salts of manganese containing a strong acid in excess^ are 

 not precipitated by sulphuretted hydrogen. 



Protosulphuret of manganese may be procured in the dry 

 way, by heating a mixture of deutoxide of manganese and 

 sulphur. Sulphurous acid is disengaged, and a green powder 

 remains, which dissolves in acids with disengagement of sulphu- 

 retted hydrogen. The same compound is obtained in the 

 humid way, when acetate of manganese is decomposed by sul- 

 phuretted hydrogen, or a manganous salt precipitated by an 

 alkaline sulphuret. The precipitate is hydrated, and of an 

 orange colour. When the protosulphate of manganese is de- 

 composed by hydrogen at a red heat, it affords an oxisul- 

 phuret. 



Protochloride of manganese; MnCl + 4HO; 788.5+450 or 

 63.19 + 36. This salt crystallizes in thick tables, which are 

 oblong and quadrilateral, of a rose colour, is very 1 soluble in 

 water and slightly deliquescent. The residuary liquid in pre- 

 paring chlorine, by dissolving peroxide of manganese in hydro- 

 chloric acid, consists of chloride of manganese contaminated by 

 a portion of perchloride of iron. To remove the latter and 

 obtain a pure chloride of manganese, the solution should be 

 boiled down considerably, to expel the excess of acid, diluted 

 afterwards with water and boiled again with carbonate of man- 

 ganese, which salt precipitates the whole peroxide of iron, 

 forming chloride of manganese with its acid (Mr. Everitt). If 

 about one fourth of the impure solution of chloride of manga- 

 nese be reserved, and precipitated by carbonate of soda, a quan- 



