Sect. III. Agriculture and Vegetation. 49 



I am not to lay down the method of ufing 

 thefe ; I mail take no notice of that, but 

 where it tends to mow their method of ope- 

 rating. My defign is to take a view of 

 thofe qualities belonging to them, by which 

 they are capable of operating on the foil, 

 and producing certain effects on the vegeta- 

 tion of plants. 



SECT. III. 



Of marl. 



TH I s is a foffil body which feels 

 unctuous and fat betwixt the fingers ; 

 and refembles clay in a great meafure, info- 

 much that marl, though a very different 

 body, is often confounded with it. It is 

 divided into many different kinds, which 

 may be all included under thefe two, clay, 

 and Hate or ftone marl : for what is com- 

 monly called Jhell-marl, is an animal fub- 

 ftance, and therefore to be claffed amongft 



E them, 



