OF FOSSILS. 231 



5 L. Artificial Limits of Solubility. 



IF folnbility ever becomes an ufeful criterion, 

 it muft be by afll^ning to it certain ncccflary ar- 

 tificial limits. Having duly confidcrcd this idea, 

 I have pronounced thofe to be-tlie beft, that can 

 be found moft eafily every where. I have felecfted 

 therefure for this purpofc mechanical pulveriz- 

 ation, a weight of water a tlioufand times hea- 

 vier than the fubilancc to be diflolved, and a 

 degree of heat equal to boiling, as boundaries 

 more proper than any others. 



5 LI. Great Extent of Solubility. 



WE are very far from believing that this li- 

 mit is to interrupt one link in the great connect- 

 ing chain of nature. Our ignorance and weak- 

 nefs have rendered it ncccflary ; and, whatever 

 fubftances bcjond it a more improved Hate of 

 fcience may difcover, we fhall refer them to the 

 clals of earths, though we give them the appel- 

 lation offulinc, as an indication ol their charac- 

 ter. As examples of Inch falinc fubilnncqs, we 

 may take the liliceous earth, which is found ab- 

 folutely diilolved at Geyfer in Iceland * ; and 

 the zeohthic, at Laugarnacs in the fame iiland (. 

 P 4 Vitriolatcd 



* EfTayi, vol. jd. p. JJI. 

 t Ibid. p. 255. 



