C "7 ] 

 Is It not more reafonable to fay that 

 vegetables contain an air, or by 

 whatever name you will pleafe to 

 call it, which by undergoing dif- 

 ferent operations changes into dif- 

 ferent forts of air ? 



Whoever therefore fays, that fuch 

 or fuch fubftance contains fuch or 

 fuch air, becaufe he extracts fuch 

 air from it by the action of fire, by 

 fermentation, or by any other means, 

 rnay fpeak erroneouily. 



Nitrous acid, or fpirit of nitre, 

 yields nothing but nitrous air when 

 it is poured upon mercury, copper, 

 iron, &c. ; but, when it is mixed with 

 iron filings in a very diluted ftate, it 

 gives, by the afliftance of a mo- 

 derate degree of heat, a mixture 

 of different airs, partly fixed, partly 

 common air, and partly phlogifti- 

 cated air, (which experiment I faw 

 I 3 at 



