174 ke Principles of Part IV. 



SECT. VI. 



Of vegetation. 



IT is worth our pains to take a fhort 

 view of what muft happen to the vege- 

 table food in the vefiels of plants. To enter 

 into a difcuffion of the anatomy of plants, 

 would be foreign to the fubject. I mall 

 take that as demonftrated by botanifts. 



THE nitrous fait being formed on the 

 furface of the foil, will be warned down 

 by the dews and rains. It will difTolve 

 what oils it meets with in its way, and 

 conftitute with them a faponaceous juice, 

 containing, befides the former principles, 

 fixed air and fixed fire. This juice will 

 be retained in the foil ; becaufe I mowed 

 by experiment, that fertile foil a&ed like 

 a fpunge with refpect to water. This na- 

 tural defcent from gravity, and the natural 

 afcent from the heat of the earth and in- 

 fluence 



