Analysis qflroft Ore. %1 



nitric acid, and the green precipitates obtained from their 

 solutions in the sulphuric and muriatic acids, prove evidently 

 that the iron they contain is very little oxygenated. But as 

 I collected all the products of the analysis in the state in 

 which they are found in the minerals after calcination, it 

 follows, that the results ought to be similar. To conclude, 

 it is easy to make the necessary correction, by admitting, 

 with ]\I. Proust*, that iron, in order to oxidate itself at the 

 minimum, augments 0*28 in weight, and 0-48 in order to 

 oxidate itself at the maximum, without, however, deciding 

 any thing upon the question of the intermediate oxidations. 

 Upon this hypothesis the proportions will be established as 

 follows : 



Real weight in grammes of the products obtained by the 

 foregoing analyses. 



Red oxide of iron, mixed with a very 



small quantity of oxide of manga- No. I. 



nese, See (G). 

 Magnesia -""'."'. 



Loss by calcination - 



Silex - 



Total grammes 



In order to estimate these products by centesimal parts, 

 it is only necessary to multiply the above numbers by 20 5 

 we shall then have the following results : 



Red oxide of iron 



Magnesia ... 



Loss by calcination 



Silex - 



Total 



The following table presents the proportions of the sub- 

 stances contained in the three specimens of spathic iron, 

 calculated on the principle that the iron in them was ox- 

 idated at the minimum, according to the proportion, given 



Journal de Physique, torn- lix. 

 C3 



by 



