1821.] and on the Composition of its Oxides. M 



pile nearly in the same way as the grey ote of manganese, 

 which, when perfectly pure, is in its chemical properties exactly 

 similar to it. The peroxide which I obtained by the exposure 

 of carbonate of manganese to the air at a temperature of about 

 500° Fahrenheit seemed to be exactly the same, when purified by 

 weak cold muriatic acid, which only serves to dissolve the car- 

 bonate that might have escaped the action of the heat and air. 



Ten grammes of deutoxide, when boiled with nitric acid, gave 

 4-703 of peroxide, which contained a considerable quantity of 

 water; two grammes, in another experiment, gave 0*935; and 

 one gramme of the first hyperoxide gave, after a long exposure 

 to a red-heat, 0*71 of brown deutoxide ; 4*793 would, therefore, 

 have yielded 3*40303, which consist of 0*258466 oxygen and 

 3*144564 peroxide of manganese; but as 10 grammes of deut- 

 oxide lose 0*75658 gramme of oxygen when reduced to prot- 

 oxide, this oxygen must be combined with 3*14456 grms. of 

 protoxide, in order to form peroxide : 3*14456 grms. protoxide 

 contain 0*74862 grm. of oxygen, and then take up 0*75658 grm. 

 of oxygen to form peroxide. It is obvious, therefore, that the 

 peroxide contains twice as much oxygen as the protoxide, and 

 it is hkewise obvious that the peroxide which I made use of for 

 the analysis contained a small quantity of deutoxide, and that in- 

 stead of 3*40303 grms. of deutoxide obtained from the peroxide, 

 I ought only to have got 3*3333 grms. 



The composition of the peroxide is, therefore, 



Oxygen 36*351 



Manganese 63*749 



100*000 

 and the artificial peroxide is a hydrate consisting of 



Oxygen 16 



Manganese 30 



Water 9 



The analysis by bisulphate of potash gave a result which differs 

 somewhat from the above-mentioned : for one gramme yielded 

 five French cubic inches, equal to 0*1421 gramme of oxygen; 

 while i ought to have got 0*1579; and 1 know of no other way 

 to account for it than by the loss necessarily produced by some 

 fibres of the paper on which the peroxide was collected. The> 

 peroxide adheres very much to the filtering paper, and cannot be 

 removed without difficulty ; and any combustible matter intro- 

 duced into the retort with the oxide of manganese would of 

 course produce a great loss of oxygen. 



There is a kind of oxide produced by the action of moderate 

 heat on the nitrate of manganese, its colour is blackish-brown, 

 jt dissolves in strong muriatic acid with some effervescence. 



