mineralogical method; different geologists of the 

 Wernerian school maintain the superior expedi- 

 ency of the other. 



The following are the advantages which are 

 supposed to be derived from a mineralogical clas- 

 sification. 



It is natural, inasmuch as it describes natural 

 combinations of known substances, just as, in the 

 organic departments of nature, these are distin- 

 guished by certain combinations of forms. 



It separates the simple from the compound 

 rocks ; referring the former to that which is con- 

 ceived their proper place in a system of miner- 

 alogy. 



It describes the same compound but once ; 

 and hence avoids the repetition which, in a geo- 

 logical arrangement, results from considering a 

 rock in two places because it occurs in two differ- 

 ent positions in nature. 



It limits the same term to the same compound, 

 and, with a nomenclature sufficiently extensive, 

 would provide a name for every rock. 



It is easy of application, as it requires nogeo- 



