iron. 



352 IRON, NICKEL, COBALT, &c. 



Expert 5. Berzelius has fixed the atomic weight of 

 Berzeiius iron at 3'39215, or (as the number should have 

 minftte been) 3 '393. His conclusion is founded upon 

 atom of tne f i] ow i n g experiment : 100 grains of iron 

 were dissolved ifl muriatic acid, and the hydro- 

 gen gas evolved being burned over lime water, 

 a quantity of carbonate of lime precipitated, 

 which weighed 4*1 25 grains. Now, this is equi- 

 valent to 0*495, or very nearly half a per cent, 

 of carbon. The solution was boiled with nitric 

 acid, to peroxidize the iron ; it was then preci- 

 pitated by caustic ammonia. The precipitate, 

 being washed, dried, and calcined, weighed 143*5 

 grains ; but, if 99'5 grains of iron yielded 143-5 

 grains, it is evident that 100 grains would have 

 yielded 144-2 grains.* Thus it follows, that pe- 

 roxide of iron is a compound of 



Iron 100 or 3-393 



Oxygen 44-2 - 1-5 



But this experiment does not seem susceptible 

 of complete accuracy, unless it were made upon 

 iron in a state of perfect purity ; for we are not 

 certain that all the carbon is converted into car- 

 buretted hydrogen gas. The strong smell of the 

 gas evolved indicates the presence of some oily 

 or bituminous substance, which may be partly 

 deposited before the combustion of the hydrogen 

 gas. Besides, different experimenters have ob- 



* Ann. de Chim, LXXVIII. 230. 



