c;8 A TREATISE ON THE CONxVECTION OF 



of vegetable matters, it may hence be inferred, that 

 these matters were not generated in, but were taken up, 

 when in a state of sohition, by the roots of plants. Thus 

 may the good effects of gypsum in America be accounted 

 for. To these beneficial effects, from the combination of 

 inflammable substances with gypsum, forming what is 

 called a hcpar or liver of sulphur, may be added the 

 large share of nourishment, which trefoils, and plants of 

 a certain formation of stem and leaf, receive, by the 

 hepatic air disengaged from hepars, when they, by the 

 process of oxygenation, are again returning to the state 

 of neutral salts, of which such hepars had been formed 

 by the combination of inflammable or carbonaceous 

 matter. 



Thus by a thorough knowledge and application of 

 chemistry to agriculture, the several substances in soils 

 may be made to undergo a varied change of new com- 

 binations, tending to promote the greatest of all obje<5i:s, 

 a more plentiful supply of food. 



NITROUS 



