234 ' CLAIMS or ■LAVOISIER. 



ported the same opinion, <and added, that it arose from a pecn-' 



liar part (the nilro-aerial) of that air : that Hales by experi- 



nient shewed the same condensation of air to take place, which 



Bayen* also by experiment afterwards confirmed. Lastly, it 



was proved by Hales, that the air, previotisly condensed in the 



process of oxidation, was liberated when the oxided metal was 



again submitted to heat: and Lavoisier afterwards observed, 



that " on operating the reduction of litharge in close vessds, 



" with Holes' apparatus, there was at the moment of the pass- 



" age of the calx into the metallic state a disengagement of 



" air in considerable quantity, at least 1000 times greater in 



" volume than that of the air cmployed."f No one, however, 



but Mayow as yet supposed that the oxidation was effected by 



—and it was a particular part of the air only ; nor was it till after the bril-. 



not till after Yi^xii discovery of oxieen gas by Dr. Priestley, that M. Lavoi- 



tiie discovery . . j_ t> & j j j 



of oxigen by sier, in repeating his experiments, found~that it truly depended 



Priestley, that q,-, ^j^g combination of that gas, and the weight acquired by the 



Lavoisier fol- . 



lowed Mayow metal corresponded to that which the air had lost. Hence 



oxidatio*i"to it ^^^^" ^"^'^ ^'''^P^ leading to the theorif of oxidation have, like those 

 in most other physical discoveries, been slow and successive : 

 and M. Lavoisier did not advance one step beyond his prede- 

 cessors, until he was made acquainted with what they were 

 ignorant of, — viz. the true composition of atmospheric air. 

 Facts observed That M. Lavoisier should deny his countryman Rey the 

 and experi- raerit of discovery because he attained to his conclusion by the 

 are of equal' force of reasoning, independent of experiment, is not a little 



authority, singular ; for as you, Sir, justly remark, " between the obser- 



JohnRevcom- ,, . „ ,, , t , , ^ i i , • ,- i- 



rnanded both, vation of well established tacts, and the making ol direct ex- 



jiid drew saga- " periments, there seems to be no essential difl"erence."| Uy 



t/ns from them, indeed, experiment alone could entitle any one to the claim of 



discovery, and it were the only mode by which truth could be 



established, what would become of the sciences of the natural 



historian and astronomer, for they obscrie only, but do not 



experiment ; and yet the science of astronomy has attained to 



greater certainty and perfection than any other can boast. 



Experiment does not supply the place, much less supersede 



* System of Chemistry, vol. i, p. 82, 1st edit. 

 t Phil. Jour. loc. cit. 

 i. '1 ractat. quinq. p. '^—4. 



obser- 



