374 DI^OXIDATION OF IRON BY pIDROGEN GAS. 



and therefore This induced me to continue the experiment. The ap« 



repeated, paratus was fitted up again as before; aqd, after I had 



^ made a considerable quantity of hidrogen gas, and taken 



the precautions aboTementioned, the fire was kindled, and 



gas was passed oyer, till no sensible absorption took place. 



All the fuel remaining in the furnace was then consumed^ 



by continuing the action of the bellows; and during this 



combustion gas was still passed over, that no water might 



introduce itself into the guubarrel during its cooling, which 



"was thus effected Tery gradually. The jar was cooled full 



of gas, and the apparatus taken to pieces as before. 



Weights. Th^^oxidule of Cogne now weighed 3-69 gr. [56 QQgrg.] 



and the oligist iron of Elba 3-32 gr. [51-28 grs.] 

 State of the The oxidulated iron of Cogne had altogether lost its 



°^ ' metallic lustre : its yellowish aspect exhibited spots separ- 

 able from the yellowish gray ground, which, examined 

 with a lens, exhibited a sort of metallic arborizations of the 

 colour of cast iron. On hammering it acquired lustre, 

 and flattened, but at length broke (owing, no doubt, to 

 the impurities of the ore). Its fracture was then very 

 brilliant, and resembling that of iron, 

 and of that of The iron of Elba had likewise lost its metallic lustre, 

 ^^^* bnt had assumed a duller, resembling that of silver. Some 



jparts had the appearance of a sponge, coloured super- 

 ficially with a fugitive tint, varying from yellow to that of 

 coarse Prussian blue, and thence to violet. All its species 

 were malleable, and were reduced thinner under the ham- 

 mer than the iron of Cogne before they broke. After the 

 experiment the specimens were analysed, to determine ex- 

 g,ctly the quantity of iron they contained. 

 The iron of The 3*69 gram. [56 '99 grs.] of iron of Cogne were 



Cogne ana- treated with nitromuriatic acid. A large quantity of nitrous 

 acid was evolved in red fumes, which proved the great dis- 

 oi[ida,tion of the oxidule. That nothing might be lost, it 

 was not levigated; which did not prevent the action from 

 being brisk, and completed in a few hours, even without 

 beating. This was necessarily the case; for, the iron hay- 

 ing been rendered very porous by the process of disoxida- 

 tion, every particle of the metal was separated, as it were 

 from the rest, and from the earthy particles^ so that the 



aci^ 



