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XLI. On the Oxidation of Metals in general, and particu' 

 tarty t/ie Oxidation of Iron. Read in the French National 

 Institute by M. Thenard*. 



xi.s soon as oxygen was discovered, researches became ge- 

 neral to ascertain its properties, and it was very soon dis- 

 covered that this gas was the universal agent of combustion. 

 Phlogiston was immediately exploded, and hypotheses to- 

 tally contrary to experience were no longer resorted to in 

 order to explain the generality of phsenomena. By admit- 

 ting the presence of this principle, more or less, in the me- 

 tallic calces, an exact account may be taken of the augmenta- 

 tion of weight which metals receive when calcined. But, 

 however simple this theory may appear at present, it was 

 nevertheless the result of a grand effort of genius. 



Wiien it was clearly demonstrated that metals, as well as 

 other bodies, so far from losing their principles by combus- 

 tion, absorbed a new one, because they are thereby aug- 

 mented in weight ; when Lavoisier taught us, that in this 

 phaenomenon, the cause of which was for such a long time 

 unknown, the atmosphere was decomposed, and that one of 

 its constituents formed a new combination, the properties 

 of burnt bodies were examined with more care ; a great 

 number of new principles were discovered in such bodies, 

 and in many of them the quantities of oxygen and of the 

 radicals which formed them were determined. These new 

 observations were again the source of many discoveries. It 

 was seen that the same combustible body might be combined 

 with oxygen in different quantities, and that consequently 

 several oxides, as well as several acids, might have the same 

 radical. Frequent applications of this principle are met 

 with, particularly in the oxidation of metals ; and at this 

 period, lead, antimony, and manganese, offer the most re- 

 markable of these applications. It was this variety of oxides 

 wliich led the author of the Chemical Statics to think that 

 there actually was not so much difference as had been pre- 

 viously believed between oxides of the same genus j and 



♦ From A/males de Cfiimie, tome Ivi, 



this 



