[ '79 ] 



Firft. Ciay, which is in general the ftificft of 

 all foils, and contains an unctuous quality. But 

 under the term clays, earths of different forts and 

 colours are included. One kind is fo obttinate, 

 that feajecly any thing will fubdue; another fo 

 hungry and poor, that it abforbs whatever is ap- 

 plied, and turns it into its own quality. Some 

 clays are fatter than others, and the fatted are the 

 belt; fome are more foft and flippery: but all of 

 them retain water poured on their furfaccs, where 

 it ftagnatcs, and chills the plants, without finking 

 into the foil. The clofenefs of clay prevents the 

 roots and fibres of plants from fpreading in fearch 

 of nourifhment. The blue, the red, and the 

 white clay, if ftrong, are unfavourable to vegeta- 

 tion. The ftony and loofer forts are lefs fo; but 

 none of them are worth any thing till their tex- 

 ture is fo loofened by a mixture of other fub- 

 ftances, and opened, as to admit the influence of 

 the fun, the air, and frofts. Among the ma- 

 nures recommended for clay, fand is of all others 

 to be preferred ; and fea-fand the beft of all where 

 it can be obtained: this mod effectually breaks 

 the cohefion. 



The reafon for preferring fea-fand is, that it is 

 not formed wholly (as molt other fands are) of 

 fmall It ones ; but contains a great deal of calca- 



rious 



