BOOK VI. 



MINERAL SUBSTANCES, AND TH 

 STRUCTURE OF THE EARTH. 



CHAPTER L 



OF SALTS IN GENERAL; 



tntroduSory Obfervatiom. Definition of Salts. Salts Jin$le and 

 compound. What are called Jimple Salts are in reality compound Bo- 

 diej.Qxj'gcnGus Principle, 



TH E earth which we inhabit* though prefenting 

 to our fenfes an almoft infinite variety of ob- 

 jects, is yet compofed, as was already intimated *, of 

 but few fimple materials. It is the moft pleafing oc- 

 cupation of the philofopher, to purfue the Proteus 

 nature through her various and aftoniming transforma- 

 tions i to develope thofe intricate combinations, which 

 conceal from the eyes of common obfervers the ele- 

 mentary principles of things; to anatomize matter; 

 and even to explain, as far as we are able, the procefies 

 by which fubftances, apparently contrary to each other 

 in their general properties, become united, and form 

 new bodies differing again in their moft efiential qualities 

 from thofe of which they are compofed. 



In purfuing this really interefting inquiry, the 

 plaineft and the cleared method that prefents itfelf to 

 my mind, is to notice feparately each peculiar and ele- 

 mentary fubflancej and. afterwards to examine the ef- 

 fects of its combinations with other bodies. In trcat- 



* See book I. chap. 2. of elementary fubllances. 



VOL. II. B ing 



