1 62 Elements of Mineralogy. 



nefs to light, and whether they be manifeftly 

 homogenous or compound fpecies, &c. 



2 dl In fome cafes one fhould try whether 

 they imbibe water, or whether water can ex- 

 trait any thing from them by ebullition or 

 digeftion. 



3 d - Whether they are foluble in, or effer- 

 vefce with acids, before or after pulveriza- 

 tion ; or whether decompofable by boiling in 

 oil of tartar, &c. as gypfums and ponderous 

 fpars are. 



4 th - Whether they detonnate with nitre. 



5 th ' Whether they yield the fparry acid by 

 diftillation with oil of vitriol, or a volatile 

 alkali, by diftilling them with fait of tartar. 



6 th - Whether they are fufible per fe with a 

 blow-pipe, and how they are affefted by 

 mineral alkali, borax, and microcofmic fait ; 

 and whether they decrepitate, when gradually 

 heated. 



7 th * Stones that melt perfe with the blow- 

 pipe a^e certainly compound, and contain at 

 leaft 3 fpecies of Earth, of which the calca- 

 reous is probably one ; and if they give fire 

 with fteel, the filiceous is probably another. 



SECTION III. 



