t 113 ] 



wont, called Gas Sy/vejtre, it lias 

 been imagined by many, that dif- 

 ferent vegetables contain alrnoft no- 

 thing but fixed air, becaufe they faw 

 that as foon as they began to fer- 

 ment they emitted really fixed air. 

 But if from this we conclude that 

 this very fame vegetable contained 

 this fixed air, as fuch, concealed in 

 its fubftance, and exifting there, as 

 it were in a concentrated or com- 

 prefifed flate, almoft as common air 

 is in a condenfing engine before the 

 fermentation began, we may pofli- 

 biy make an erroneous conclusion ; 

 for it may be that this vegetable did 

 not contain more fixed air as fuch 

 than inflammable air ; but that a 

 part of the fubftance of the vege- 

 table has undergone fuch a change 

 by the action of the fermentation 

 as to become what is now called 



