ON A NATURAL SYSTEM 



We nre not here to have any rcfpeft to fictitious 

 valuation. Rut as the arrangement of foflils is 

 made with a view that our knowledge of them 

 may be eventually ufeful and advantageous, it 

 may iecm to militate again/I this defign, if we 

 were to feck among the bafer kind for all thole 

 noble minerals, whofc intrimic value can defray 

 the labour and coll of chquation, 



The feveral cufcs propofed ought not to be 

 coniklcred as imaginary, as they each of them 

 occafionally occur, and will be rendered more 

 clear and intelligible by application in the fol- 

 lowing fedlions. 



5 LXIV. Genera of Salts. 



INT falts, we difcoyer two genera, by no means 

 ambiguous ; the acid, and the alkali. Chemif- 

 try has not yet been able to cxtnicl their proxi- 

 mate principles; but, that they are different 

 from, and oppofite to each other, there is not 

 the leaf I room to doubt. 



LXV. slcids. 



AN acid is eafily difcoverable by the tafle, by 

 its property of changing to red the blue vege- 

 table colours, and of cffervefcing with aerated 

 alkalis. 



