1824.] the Oxidum Manganoso-Manganicum. 273 



weighed 0*442 gramme. The filtered solution was digested with 

 an excess of caustic potash ; the precipitate formed was collected 

 on the filter and washed. The alkaline ley which passed through 

 was examined by the usual reagents, but it was not found to 

 contain any thing in solution. The precipitate by the caustic 

 potash was dissolved from the filter in muriatic acid. The solu- 

 tion, after being neutralized by ammonia, was mixed with some 

 drops of oxalate of ammonia, but the liquid continued clear. It 

 was afterwards mixed with succinate of ammonia as long as any 

 precipitate fell. The succinate of iron thus obtained was sepa- 

 rated and washed. Being; heated to redness the residual oxide 

 of iron weighed 0124 gramme. 



As this 0*124 gramme of oxide of iron, together with the 

 0-442 gramme of silica and matrix, must be separated from the 

 3 grammes of the mineral examined, the residual pure oxide of 

 manganese amounts to 2434 grammes ; and consequently the 

 4*81 grammes of the heated mineral in a contained 3*902 

 grammes of pure oxide. If to this we add the 0*22 gramme of 

 gas and water driven off in a, the whole quantity of the mineral 

 freed from foreign matter was 4' 1 22 grammes, and its consti- 

 tuents were, 



Oxygen, a . . . . 0*143 

 b.... 0*458 



0*601 14*58 



Water, a 0*077 1*86 



Oxidum man.-mangan. 3*444 83*56 



4*122 100*00 



The small quantity of water may be considered as mechani- 

 cally lodged in the mineral. 83*56 parts of oxidum manganoso- 

 manganicum contain 22*71 parts of oxygen. Thus the remaining 

 60*85 parts of manganese had been united with 22*71 + 14*58, 

 or 37*29 parts of oxygen, which for 100 parts amounts to 61*45. 



The superoxide of manganese is considered as a compound of 

 100 metal and 56*213 oxygen. The oxygen found in the mine- 

 ral, therefore, is too high ; but this is probably owing to some 

 error in the analysis, the principal object of which was not to 

 determine the constitution of the superoxide, but only to ascer- 

 tain if the mineral was in this higher state of oxidizement ; and 

 the result shows clearly that the manganese was in the state of a 

 superoxide. 



Mineral superoxide of manganese is easily distinguished from 

 the hydrate by the different colours of their powders. The pow- 

 der of the superoxide is a full black, while that of the hydrate on 

 the other hand is yellowish-brown. We have only to scrape the 

 minerals with a knife ; the difference is immediately seen. 



Protoxide of Manganese. 



A globular cavity was blown in the middle of a barometer 

 New Series, vol. vn. t 



