366 
CHEMICAL PRINCIPLES. 
Oxides of 
manganese. 
a part of the same to the state of gaseous oxide de carbon. This 
green oxide was therefore a suboxide, containing half as much 
oxigen as the manganeous oxide. For the trifling difference 
between 14 and 15, may naturally be attributed to some imper- 
fection in the experiment. Bergman observed that manganese 
kept in a bottle imperfectly closed, falls into a powder ; and 
that this powder has the property of decomposing water. I 
had an opportunity of verifying this observation of Bergman. 
Half an ounce of manganese being kept in a bottle closed 
by a cork, I found, after the expiration of a year, that the 
metal had fallen into a coarse metallic powder, which, when 
pounded in a mortar, took a colour that was rather lighter- 
On being thrown into water, it caused a disengagement of 
hydrogen gas. In the muriatic acid also, the same effect 
was produced with great vivacity. As to this powder, is 
it a suboxide inferior to the green suboxide ? I have not yet 
been able to make any experiment'conclusive of this matter. 
But from those I have made, I shall rather determine it to be a 
mechanical mixture of carburet of manganese, which does not 
oxidate in a dry air, and of oxidated manganese. 
The superoxiduin mangan.ic.um, (or the native oxide which af- 
fords oxigen gas, when heated to a red heat) is not the same as 
the black oxide of whicli I have already spoken j for it is 
reduced by fire to the state of that black oxide (oxidum man- 
ganicum). And, as Scheele first observed, the manganeous 
oxide (obtained by the decomposition of the manganeous carbo- 
nate in suitable vessels) has the property of kindling at the 
temperature of melted sulphur, and then forms the manganic 
oxide, which is of a blackish brown, or almost as black as the 
super-oxide. I will not say that the chemists have confounded 
these two oxides. But. so far as I am informed, they have 
»aid nothing positive concerning the marks by which they are 
distinguished. It is an easy matter, by means of the chemical 
proportions, to determine what the composition of this super- 
oxide should be ; since it or.ght to contain twice as much oxi- 
gen as the manganeous oxide. In fact, M. Klaproth, in an 
analysis , of a fossil manganic super-oxide found that it yielded 
nearly 
