OF FOSSILS. 233 



LI n. Metals. 



PERFECT metals arc caiily diflinguifhcd by 

 their opacjiic (liming furfuccs and fpccific weight. 

 Their malleability, which Cronllecit cuniidcrs as 

 their peculiar chant clcr, is no general criterion; for 

 we reckon ulmoft as many brittle as duclile metals. 



5 LIV. Phhgijlic Sub/lances. 



A CURTAIN degree of levity, with as much 

 phlogifton, loofely combined, as will occufion in- 

 flammation, is ncecilary to the conftitution of all 

 bodies denominated phlogiilu:. Solubility in oil 

 is not a diftinguifliing property of this clafs; as 

 that mcnftruum, though producing no e Heel on 

 plumbago, yet ach violently on lead, copper, 

 arfenie, and other metal*. 



5 LV. Mixed Ff Jfils. 



WIIILI: \\c arc giving our attention to thcdi- 

 iliiicl arrangement of the ieveial elafles, it will 

 be ealily feen that we mean to conii'der fuch 

 foilils only as are in a ilatc of purity; that is to 

 fay, free from every corruption by combina- 

 tion with the fubjccls of other chuTes, not ncccf- 

 fary to their compolidon. Sulphurated metals, 

 p;r example, belong to two elafles ; and we are 



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