OF FOSSILS. 235 



fame time fulphur and aeriform fluids *. Mofl 

 phlogiftic bodies likcwifc, perhaps indeed all, 

 contain an acid united in their very conftitu- 

 tion. 



LVIII. Slffuiity of Earths with Mctah. 



EARTHS rcfemble tlic calces of metals in ma- 

 ny of tiieir properties ; but in rcfpecr, to fpccific 

 gravity, the faculty of colouring glafs, and their 

 reduction to the metallic Hate, they arc cflciuial- 

 ly dill ere nt. 



5 LIX. Sulphureous Character of Mctah. 



METALS in their perfcdl ftatc arc cither me- 

 tallic acids faturatcd with phlogiflon, or a fpc- 

 cies of metallic fulphur, which arc fometimcs 

 very evidently fufccptiblc of inflammation, as 

 7.inc and arfcnic. Gold and copper, when in 

 fufion, afford fomc appearance of flame, though 

 faint,inagrccnifli vapour; bright fparks are emit- 

 ted from iron in a white heat ; and tin alib may 

 bc inflamed by a proper manner of operating. 



S J<x. Stones, 



IN the claflcs already enumerated, all fofllls 

 ?:-n by no means included. Such as arc compo- 



fcd 

 Vol. ii. p. 352. 



