ON A NATURAL SYSTEM 



kingdom. Under this head we may arrange 

 the aerial ucid. 



cxi I. Great Number of Acids. 



IF we confidcr, that probably the exiftcnce 

 pf all metals depend upon their peculiar radical 

 acids ; that vegetable* evidently contain a num- 

 ber oi* unknown acids ; and that, perhaps, the 

 fume may be laid of anin.als alfo; we have rea- 

 fon to wonder at the abundance and variety of 

 this fubltanee, and to let a high value on its u- 

 tility and importance in the a-conomy of na- 

 ture. 



5 c x u \ . Species of dlku line Sa Its. 



THE extent of the other genus is confined 

 within very narrow limits, i'or a long time 

 three fpecies only of alkaline falls were known; 

 two of which could bear a flight ignition, and 

 were therefore denominated fixed ; while the 

 Other was diilinguiihcd by its volatility. 



5 ex iv. Fixed sllkalies. 



Or the fixed alkalies the one feems to prevail 

 in the vegetable, and the other in the mineral 

 kingdom; from which they. both derive their 

 names. 



cxv. 



