Examination of the Peroxide of Manganese. 83 



salt. The best test I have met with for distinguishing them 

 from the soluble proto-salts, to which they in appearance bear a 

 great similarity, is the yellow prussiate of potash. With the per- 

 salts it gives a greyish green precipitate, while with the protox- 

 ide solutions the precipitate formed is white or whitish pink. 

 The hydrochlorate of platina is also a good test for them, as with 

 them it forms a yellowish precipitate, but with those of the prot- 

 oxide, it forms none. 



Sulphuretted hydrogen. — When this gas is passed over the per- 

 oxide placed in a tube, which at the same time is heated, the gas 

 is decomposed, sulphur and water are given off, and the oxide is 

 converted into a sulphuret of a light green color. The gas 

 must be passed over until the tube becomes cool, for if the sul- 

 phuret be exposed to the air while hot. it inflames, acting the 

 part of a pyrophorus. When digested in fuming nitric acid, a 

 violent action takes place, the sulphuret is decomposed and con- 

 verted into a proto-salt, and all the sulphur is precipitated. Ana- 

 lyzed in this manner, it gave 9.6 per cent, of sulphur, and when 

 heated in the open air until the sulphur was burnt out and the 

 oxide converted into manganoso-manganic oxide, it yielded 100 

 percent, of manganoso-manganic oxide, which contains 72,178 

 per cent, of metallic manganese. Now 9.6 of sulphur will com- 

 bine with 16.51 of manganese, which makes 26.11 per cent, of 

 sulphuret. There then remains 55.67 per cent, of manganese, 

 which, if considered as manganoso-manganic oxide, would form 

 an oxy-sulphuret, containing 



Sulphuret of manganese, - _ - 26,110 

 Manganoso-manganic oxide, - - 71.893 



98.003 

 Thus in the operation, both the oxide and sulphuretted hydro- 

 gen are decomposed. The oxide is partly reduced to manganoso- 

 manganic oxide, and partly to metallic manganese. The sul- 

 phur from the sulphuretted hydrogen is mostly driven off, but 

 some of it combines with that part of the oxide which has been 

 converted into the metal, while the oxygen from the oxide, and 

 the hydrogen from the gas, unite and pass off under the form of 

 steam. This oxy-sulphuret very much resembles the substance 

 formed by gently calcining the red sulphuret in a close vessel, 

 (during which operation sulphuretted hydrogen is given off,) but 



