44 A TREATISE ON THE CONNECTION OF 



these acids on chalk fixable air is disengaged. This gas 

 is absorbed by the roots of vegetables, decomposed in the 

 pro:ess of vegetation, affording the carbonaceous prin- 

 ciple to vegetables ; whilst vital air, the other constituent 

 part of fixable air, is thrown off by the respiratory power 

 of vegetables. 



The different effects of lime and of chalk on vege- 

 table and animal substances, shew, that when either of 

 those materials is applied with a view to promote the 

 fertility of the ground, they should be used according 

 to circumstances, and the nature of the soil. 



PAR 



