CHEMISTRY OF SOIL. 25 



an act to be deprecated, where an old one will as well 

 answer. But there is no old term, which includes 

 the substances, to which, in the present subject, ref- 

 erence must be frequently made. It is more conve- 

 nient to use a new term defined, than to enumerate 

 by name, several substances, whose action in agri- 

 culture has a common character, whenever this ac- 

 tion is mentioned. The word inflammable, or acid- 

 ifiable combustible, the usual chemical designation 

 might be used. But the farmer wants some more 

 expressive term, which, while it conveys all that is 

 intended by the common word, shall also remind 

 him of the peculiar character of those compounds 

 with metals, and with each other, which by common 

 consent, end in " uret." This word, from the Lat- 

 in, " wror," to be burned, seems well adapted to ex- 

 press the character of inflammability, while, by its 

 addition to carbon, &c, it forms the common 

 chemical designation of the class when combined 

 with metals. 



41. The elements which make up all rocks, may 

 be conveniently divided into four pairs, which are, 

 the alkalies, potash, soda. 



The alkaline earths, lime, and magnesia ; the 

 earths, silex, and alumina. 



3 



