PHYSICAL AND LITERARY. 3 



SECTION L 



THE moft known properties of marie 

 are, its efFervefcing with acids *, and fer* 

 jilizing the foil to which it is applied. 

 By thefe two properties I was directed in 

 ?he profecution of njy inquiry. 



Among 



• I know that Dr Hill, in his volume upon Foffils, has 

 ranked among marles many fubftances which do not ef- 

 fervefce with acids. But I cannoc fee by what reafon fuch 

 an arrangement can be juftified. Perhaps, all the fub- 

 ftances which we 6nd in the clafs of marles have, with 

 advantage, been employed in agriculture- But that is 

 net fofficient. We know that pure clay itfelf, applied to 

 certain foils, produces the moft happy cffedls. Ail Dr 

 Hill's non»efFervefcent marles are poffeired of the diftin- 

 guilhing properties of clay ; and therefore ought in ju- 

 ftice to be ranked among the argillaceous bodies. Afier 

 comparing this author's definition of marie with hisdefi> 

 nitions of clay ^nd bole, I can fix upon no particular cha* 

 rafter by which the firft of thefe fubftances may, with 

 certainty, be diftinguiflied from the other two. Marie 

 fecms by his definition to differ from clay and bole in de- 

 gree ot vifcidity only. But, how fhall the degree of vifci- 

 dity which conftitutes a clay, or a made, or a bole, be 

 afcertained ? A very confiderable number of earth-marles 

 are of a ftoney hardnefs ; but all marles, by Dr Hill's dg- 

 fiaitioD, cohere ilightly. 



