ON A NATURAL SYSTEM 



published, I have overlooked the mutual pro- 

 portions; hut, on further reflection, I find the 

 confideration of them abfolutely neceffary. 



cxxxv. method of invejligatingtbc/trviral Spt* 

 ties tf Earths, 



IN order to determine with accuracy the fpe- 

 cics of earths, which hitherto feem to have red- 

 cd on no very certain foundation, it will be re- 

 quire to explain carefully this doctrine. Ijct 

 the five primitive earths be indicated by five 

 initial letters, the ponderous b> p, calcareous by 

 r, magnefian by m, argillaceous by a, and iili- 

 ceous by /. 



J cxxxvi. Continuation. 



AT firft we will attend to 'the character only 

 and number of principle*; and, by means of the 

 doctrine of comi,inatiun$, it will be eaiy to af- 

 certain how many fpc-cific coniociations can arife 

 from thefe five letters. 



For example, />, r, ///, u, and /, can produce nt 

 more than ten double ipecies 



pc, />/;/, pa, fs t 

 cut, ca, cs t 

 inn* ins, 

 as. 



Of 



