378 IRON, NICKEL, COBALT, &c. 



decomposed ; hydrogen gas being evolved, 

 while the manganese lost its metallic lustre and 

 assumed a green colour : 80 parts of manganese 

 thus treated, became 92 parts of the new oxide. 

 Now, 80 : 12 i : 3-5 : 0-525. Hence it would 

 appear that this oxide, which I have not had an 

 opportunity of examining, is a compound of 1 

 atom manganese and half an atom of oxygen ; 

 or of 



2 atoms manganese . . 7 

 1 atom oxygen ... 1 



This oxide is incapable of uniting with acids ; 

 but Dr. Forchhammer has made a set of experi- 

 ments to show that it combines with sulphur, and 

 that it constitutes the mineral found in Transyl- 

 vania and Cornwall, and considered at present 

 as a sulphuretted oxide of manganese. It seems, 

 however, proved that the Transylvanian ore is a 

 sulphuret of manganese. 



I think the existence of the supposed protox- 

 ide of manganese of Berzelius exceedingly 

 doubtful. But I see no reason to doubt the ex- 

 istence of the suboxide of John though that 

 chemist was mistaken in considering it as the basis 

 of the salts of manganese. The real basis is the 

 substance which I have here distinguished by 

 the name of protoxide, and which contains just 

 twice as much oxygen as the suboxide of John. 



