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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 
per cent. 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, - wp <9 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 ina close vessel, 
(during which operation sulphuretted hydrogen is given off,) but 
