O F F O S S I L S, 123 



} xxxiv. U/eqftbeBhw-Pipein Qryttohgy. 



NOR c?,n \vc p ift over in filence the great u- 

 tilityofth'.* blow-pipe in oryclology, by itsfpce- 

 dv an;l concifc mo.le of operating. With it a 

 few minutes arc fufficient to examine the nature 

 ofafoflil, upon a piece of coal, orinafpoonofgold, 

 and to obfervc all the changes from beginning to 

 end; which for the in oft part is not poilible in a 

 crucible; notwithitanding in this way, it re- 

 quires feveral hours before the rcfult of the pro- 

 ceis can be known*. 



xxxv. Klofl of the Principles of Fofltis are 

 difcovered by Fire. 



IT muft, however, be acknowledged, that, 

 in many cafes, the principles of foil! Is may be 

 afcertained by the proper application of lire; 

 unlefs, by the number or delicacy of fuch prin* 

 ciples, the cornpofition of the foflll is rendered 

 too complex and intricate. 



xxxvi. But not every Principle. 



THERE arc many circumflanccs that will pre- 

 vent us from confidcring fire as the fupremc ar- 

 biter of compofition, though fupportcd with all 



the 



* EHayc, id tol. page 45$. 



