IRON. 3,55 



Consequently, when 100 parts of pure iron are 

 converted into peroxide they become 142*857. 



7. Peroxide of iron has the property of com- 

 bining with water, and forming with it a per- 

 hydrate. This compound is found native, and 

 constitutes what the Germans call brauneisen- 

 stein. D'Aubuisson first showed it to be a per- 

 hydrate of iron. Very frequently it is mixed 

 with a little oxide of manganese and silica. 

 This is almost always the case with the variety 

 called hematite. But when the perhydrate is 

 pure, it is a compound of 



1 atom water . 1-125 



1 atom peroxide of iron 5 



6-125 



A portion of this water is very easily dissipated : 

 hence, unless very carefully examined, the por- 

 tion of water will turn out rather less than an 

 atom. 



8. I found, many years ago, that when 100 

 parts of iron are oxydized by passing the steam 



of water over them at a red heat, they combine Lussac 

 with 29'7528 parts of oxygen.* Bucholz ana- 

 lyzed iron by the same process, and found that 

 100 grains of the oxide thus obtained, when 

 converted into peroxide by nitric acid, became 

 110 grains. Hence, he inferred that 100 oxy- 



* Nicholson's Jour. XXVII. 378. 

 Z2 



