M4 ON A NATURAL SYSTEM 



the afllftance of the dry way ; and it may be 

 fuflkient to enumerate fome of the moft confi- 

 de rable. 



S xxxvn. 



fallacious. 



FIRE tends to confound all principles toge- 

 ther, except thofe of metallic bodies which are fe- 

 parated from their matrices ; it is therefore not 

 at all calculated to extricate the fcveral ingredi- 

 ents of compofition. 



$ xxxvin. 7be Efficacy of Tire cannot be de- 

 fned with any certainty. 



AN accurate and eafy meafure of the power 

 of this element is yet wanting. A fcflil refills a 

 certain degree of heat, that will yield to one 

 more intenfe ; and there are perhaps a very few 

 that are deemed altogether rcfru&ory. 



xxxix. And it is variable alfo. 



IT is not uncommon for the fame degree of 

 fire to melt fome varieties of the fame fpecies, 

 while upon others, it feems not to have the 

 fmallcfl influence. The petrofilices, feltfpat, 

 and other foflils, afford examples of this kind. 



4 XL. 



