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of fads long eftablifhed by multiplied experience; and that 

 of the fecond by the application of more general principles to 

 the explanation of thofe fads. — But before we proceed to either 

 branch of this queftion the diftindions and denominations 

 both of foils and manures muft be exadly fettled and accurately 

 defined. 



CHAP I. 



ni ; lu 

 Of SOILS and MANURES. 



SECT I. 0/ S O I L S. 



Land, confidered as the bafis of vegetation, is called 70//. 



Soils confift of different combinations of two or more of 

 the four primitive earths, namely, the calcareous (which I 

 fometims call mild calx), magnefia, argill, and the filiceous. 

 For a more accurate defcription of thefe I muft refer to books 

 of mineralogy, and fhall only remark that by calcareous 

 earths are meant chalk, and all ftones that burn to lime ; 

 they are eafily diftinguiflied by their property of effervefcing 

 with acids. 



Magnesia 



