Sect. III. Agriculture and Vegetation. 57 



fome meafure, this production of nature, 

 but fall vaftly fhort of her in the equality 

 of the mixture, and perhaps to in the fub- 

 tility of the particles. 



THERE is a body very ilmilar to marl 

 in its appearance, but very different from 

 it in its effects, and often found in the fame 

 bed with the beft marl. It is of a darkim 

 lead colour. Inftead of fertilizing ground, 

 it renders the beft foils incapable of bearing 

 any kind of vegetables for many years. I 

 have feen the fpots on which it was laid 

 entirely barren three years after. I have 

 heard of its effects continuing in other places 

 for a much longer time j nor is it certainly 

 known when its bad effects' will end. A 

 body fo very deftru&ive to agriculture, de- 

 ferves to be well charadterifed, in order to 

 be munned ; and well examined, that we 

 may know whence proceeds this noxious 

 quality, and how to cure it when it has 

 taken place. 



THOSE 



