9^^ Rt-;ii ;rh on Azz*. 



always a produ6l of the operation, and not having exiftc^ 

 before the txperuiicnt under the form of azot in the air exa- 

 mined ; Humboldt, who is fond of drawing general conclu- 

 fions fi im fingle lafts, feems to have been deceived when he 

 advances that earths might be cniploved to determine the 

 (inantity of azot contained in atmofpheric air: earths do not 

 indicate the aaol contained in the atmofpheric air, they 

 change that aw into azot." 



Young SauOlire * has formally contradiftcd the refult an- 

 nounced bv Humboklr. He agrees! that the humus, which 

 is the refult of a mixture of decompofcd vegetables with 

 others not yet decom])ofed, abforbs oxygen gas, and is a fact 

 well known; but he attcfts that " this eftcft does not take 

 place when the tartiis arc pure, and deprived of all vegetable 

 iubitance." He defcribes feveral experiments wliieh he 

 made with aluminj calcareous earth, and filex. 



In the Journal de Pbvjique for Pluviofe the fame y.ear, 

 there is an anfwer of Humboldt, written in a magiftcrial 

 tone, which contains nearly the alfertions contained in the 

 firft memoir, with a kind of atteftation, becaufe he made his 

 obfervations in the laboratories of Vauquelin and Pourcroy. 

 This authority would be impofing, if thcfe two learned chc- 

 mids had co-operated in the oljfcrvations ; but fo far from 

 this, we fee bv the IhUement that the only expcrimezits tried 

 in their prefence would not fucceed. 



I have been afllired that the celebrated Fabbroni, of Flo- 

 rence, repeated the experiments of Humboldt at the fame 

 period with'uit fucccis. 



■Champy the fon, a verv correft obftrver, repeated them 

 at Cairo on alumin, on lime, and on the mud of the Nilc^ 

 at a temperature which varied from nearly 30 to 36 dearccs 

 of the centigrade th.emiometer, but he obtained no abforp- ' 

 tiour it is to be remarked that tlie mud of the Nile contains, 

 fome remains of veoetable fnhltances, fo that when diftilled 

 there is extracted from it a certain quantity of cirrbonic acid' 

 and carb.onated b\ drogen gas. 



Chaptal repealed them at Mtvntpellter without obtaiuiiig 

 an al^forpti!)!!. 



* J<jht>!uJ de VhTiiiue, Frini;iire, an. 7, 



" • ' I kept 



I 



