The Conclufion. $6$ 



And fmce we find fo great a quantity of 

 air infpired and mixt with the fap , and 

 wrought into the fubftance of vegetables , 

 the advantage of ploughing and fallowing 

 ground feems to arife not only from the 

 killing the weeds, and making it more mel- 

 low, for the fhooting of the roots of Corn ; 

 but it is thereby alfo the better expofed to 

 have the fertilizing, fulphureous, aereal and 

 acid particles of the air mixt with it, which 

 make land fruitful, as is evident from the 

 fertility which the fword or furface of land 

 acquires, by being long expofed to the air, 

 without any culture or manure whatever. 



We have feen many proofs of the great 

 quantities of liquor imbibed and perfpired 

 by plants, and the very fenfible influence 

 which different ftates of the air had on their 

 more or lefs free perfpiration : A main 

 intention therefore to ,be attended to in 

 the culture of them, is to take due care, 

 that they be fown or planted in proper 

 feafons and foils, fuch as will afford them 

 their due proportion of nourilhment 5 which 

 foils, as they are exhaufted, muft, as 'tis well 

 known, from time to time, be replenifhed 

 with frefli compoftj fuch as is full of faline, 



iulphu- 



