ON A NATURAL SYSTEM 



eleven metals only wereknown ; butithadfcarcc 

 grown forty years older, before the diicovcry 

 \vas made of platinu, a noble and 'ductile metal, 

 find of three or four others, that were not mal- 

 lenble, as cobalt, r.iccolum, magnefium, and fi- 

 clerum, which lad has hitherto appeared to dif- 

 fcr from all the red *. The fifth in molybde- 

 jw is not yet diffidently explored, to determine 

 whether it fliould be reckoned among thofe al- 

 ready known, or conllitute a new fpcues ; and 

 to the fixth, in the acid of the lapis pondcrofus, 

 we may apply the fame obfcrvation. Of thcfe 

 two, however, we are in hopes the c ha racier of 

 the full will be Loon dilplajed by the indullry 

 of Mr IJiclm. The genera of rnctuU, therefore, 

 of which we can be certain, amount to iixtcen, 

 or fifteen at lead ; and it is not unlikely that 

 this number will be increufed by future diicove- 

 ries. 



LXXXII. Arrangement of mixed Metals. 



IN feet ion Ixiii. we have a queilion refpeding 

 the genera of minerals containing two metals, 

 the one of which is more valuable than the o- 

 ther, but in lefs quantity. Examples of fuch 

 minerals we find in the golden pyrites, which 



hold 



* Meyer am! Khprotliius have proved it to be iron joined 

 to the phofphoric acid ; and our author, convincccfby their 

 arguments, changed lu opinion* 



