ON THE OXIDATION OF IRON. 14jf 



Doubting the possibility of fixing the limits of oxidation, 

 and obtaining an oxide containing so large a proportion of 

 oxigen, I imparted to you my thoughts on the subject. 

 You hinted to me, that you had little confidence IQ the re- 

 sults announced by Mr. Darso; and, as I thought it of im- 

 portance to the opinion concerning the different terms of 

 oxidation of iron to verify the fact, I sought an opportunity 

 of doing this. 



The lectures on mineralurgy, which I give every year at The author. 



the school of Mining at Moustier, enabling me to make a '^ujreson mi* 



n ii_i neralurjy. 



number of chemical experiments, which are repeated by the 



pupils sent thither by government, who have already ac- 

 quired considerable knowledge of the subject at the Poly- 

 technic school, I determined this year to repeat the experi- 

 ments of Mr. Darso, and employ Mr. Desroches, a pupil, 

 to do the same. 



Following as exactly as possible the process described by Darso'sexpe* 

 Mr. Darso*, we endeavoured to perform it with more care p^^ sre " 

 and attention, in order to obtain results, on which others 

 might depend. 



As it was possible, that some of the substance of tho test, The iron fil- 

 the cupel, or the mortar, might have mixed with the iron, in g s arst ana * 

 and contributed to the increase of its weight, we first ana- 

 lysed the iron tilings, which we proposed to calcine. By 

 this analysis we found, that the iron we calcined contained a 

 little carburet of iron and silex, but in too small quantity 

 to be weighed, with a trace of alnmine and of lime. 



The iron filings, weighed separately, were put into a Process de- 

 porcelain capsule, weighed with the capsule, and then 

 placed under the muffle of a cupelling furnace. After 

 having calcined them for a larger or shorter time, the cap- 

 sule was withdrawn, and set to cool under a glass, that no 

 extraneous matter might get into it; after which they were 

 weighed with the capsule, triturated, and then weighed 

 with the capsule afresh. These operations were repeated P 



nine times following, and the iron increased 42*224 per 

 cent, after which it received no farther increase. 



* Certainly not at the commencement, for the filings were not stirred, 

 nor was the air renewed, till after nine successive calcinations of several 

 hours each. T. 



I snail 



