346 IRON, NICKEL, COBALT, &c. 



atom of oxygen to the iron, and then flies off 

 in the state of sulphurous acid. Now, 1 atom 

 of oxygen will convert 2 atoms of protoxide of 

 iron into peroxide. It is obvious from this, that 

 one half of the sulphuric acid is decomposed, 

 and that the other passes over in the state of 

 fuming sulphuric acid. Now, this fuming acid 

 I have carefully analyzed, and I find it a com- 

 pound of 



2 atoms sulphuric acid = 10 



1 atom water . = M25 



11-125 



Let us suppose that a quantity of protosul- 

 phate of iron, equivalent to 4 integrant particles, 

 or 69*5 grains (17*375 x 4) of the crystals, are 

 treated in this way. By exposing them to a heat 

 of about 600, they lose 3O375 grains, or the 

 whole of the water, except one atom. There 

 remain 39*125 grains, composed of 



4f atoms sulphuric acid = 20 

 4 atoms protoxide of iron = 1 8 



1 atom of water = 1-125 



39-125 



When a strong heat is applied to this residuum, 

 half the sulphuric acid, or 10 grains, is decom- 

 posed into 



2 atoms of sulphurous acid 8 

 2 atoms of oxygen = 2 



10 



