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THE laws of generation perfiiade ws to commence our claffification 

 in earths, but the laws of fyliem are repugnant. 



For earths by general confent, conftitute a natural order, and 

 (hould not therefore be divided into different clalfes. 



Congeneric fpecies, fhould likewife be feparated from others of 

 a like genus: ior (oma clays refill the greatcil degrees of heat, 

 others ire <;:alcareous. 



Ochres ^Ifo fhould precede Metals, before the idea of Metals is 

 given, vvhofe progeny they neverthelefs are; yet fome Ochres 

 muft be referred to Copper, fome to Iron, Bifinuth, &:c. 



Some fpecies of earths are primitive and (hould precede rocks; 

 others are derivative and fhoukj be placed after them. 



If FoflTis be divided among Stones or Minerals, then Tophs 

 and Staladlltes would be feparated from their natural genus and 

 didributed among different ones. 



Many petrifa£\?ons would be placed among calcareous rocks, 

 fome among combuitibles^ others aiTion<^ Pyrites, Copper, Bi- 

 tumen, &c. 



CRYSTALS I would have placed among the Salts; but toprovent 

 a mere oifpuie about words, he that thinks fit may eafily fubllitute 

 the term Lryftal in the room of Salt. For is it not the fame thing 

 to fay that Salts have determined their figure under the generation 

 of Salts, or that they are the conltitutive elements of Salts ? 



