ON THE OXIDATION OF IRON. 15 J 



Calculating the increase of weight in each calcination, Only 42-S24 



and the losses of each trituration, we find, that, after five ° f " X1 f n to 



100 of iron. 

 successive calcinations, the iron increased 42*224 per cent: 



by this process therefore we cannot carry the oxide of iron 



farther than 42$ of oxigen to 100 of iron. 



To satisfy ourselves whether any foreign matter beside No foreign 



the oxigen had combined with the iron, we analysed the sub *&»nce pre- 



. sent, 



oxide. This analysis, like that of the filings, yielded us 



an imponderable quantity of silex, and a trace of lime and 

 alumine. Hence it follows, that no earthy substance had 

 combined with the iron, and that the metal had lost during but the carbon 

 calcination the carbon it contained before. lost * 



As iMr. Darso says, that he was constantly stirring his The oxide stir- 

 oxide of iron during; the calcination, and renewing the air red , an( ! t>,0W , Ii 

 .... „ •£•»!! i • on during cal- 



in contact with it by means of a pair of bellows; and as it cination 



was possible these two causes might have contributed to the 

 combination of a greater proportion of oxigen with the 

 iron, we resumed the experiment where we left off, and 

 continued the operation on 3 grammes, at 42{ of oxigen 

 per cent, which we had left, stirring and blowing on them. 

 As it was possible however, if we used an iron hook to stir 

 the oxide, that this hook might have been oxided, and part 

 of its oxide mixed with that of the filings, so as to increase 

 its weight, we fixed on the extremity of an iron rod a hook 

 of glass, which we -changed as often as it appeared to grow 

 soft from the heat ; and with this substance we stirred the 

 oxided iron. 



The three grammes of iron oxide were exposed seven gained 2-776 

 times successively to the heat of the furnace under a muffle, more of oxigen 

 and afterward triturated. The muffle was heated to the tions 

 highest degree, the oxide was stirred during the calcination, 

 and the air in contact with its surface was constantly re- 

 newed by means of a pair of bellows. In the earlier ope- 

 rations the oxide increased in weight ; so that at the fourth 

 there were 45 of oxigen to 100 of iron : but when it had but would not 

 reached this point we could not combine any more oxigen take up more, 

 with it, so that it remained constantly at 45. 



These, Sir, are the results we obtained by repeating the 

 experiments of Mr. Darso, and they coufirm the opinion, 

 that the oxidation of iron at a maximum does not exceed 



45 of 



