IRON. 353 



tained different results in this way. I made two 

 experiments with great care. In one, 100 iron 

 were converted into 142*6 of peroxide j in an- 

 other, into 144*75 grains.* 



Hassenfratz found that 100 grains of iron, 

 calcined on a cupel, were converted into 142*224 

 grains of peroxide.t In another experiment, 

 100 iron, when thus treated, became 145 per- 

 oxide. 



JBucholz, by an experiment similar to that of 

 Berzelius, obtained 142 grains of peroxide from 

 100 grains of iron.t 



Gay-Lussac, from 100 grains of iron, obtained 

 142*35 grains of peroxide. 



The mean of all these experiments gives 

 43*303 for the quantity of oxygen which unites 

 with 100 of iron. Hence, peroxide of iron ac- 

 cording to these experiments is composed of 



Iron 100 or 3-463 



Oxygen 43-303 - 1-5 



Now, 3*463, the atomic weight of iron de- 

 duced from these experiments, approaches nearer 

 to 3*5, the weight deduced from the experiments 

 above described, than to Berzelius' number. 



6. I determined the atomic weight of the Atom of 

 peroxide of iron in the following manner: 7*5 fron deter- 

 grains of cubic pyrites, very carefully selected, m 



* Nicholson's Journal, XXVII. 378. f Ibid. XXVI. 149. 



t Ibid. XXV. 353. Ann. de Chim. III. 356. 



Vor,. I. Z 



