17S A SYSTEM OF 



requires an explanation, fince the author in his 

 description does not obferve the neceffary diftinc- 

 tion between alcaii and lime , and quotes the horn 

 filver ore, and the lima cornea^ as proofs of his 

 opinion •, by which, however, his opinion feems 

 rather weakened than confirmed. 



SECT. CLXXIX, 



3. Platina del Pinto, Platina di Pinto, Juan 

 blanca. 



This metal is a recent difcovery of our 

 times, and is defcribed with great accuracy 

 by ScherTer, in the Ads of the Royal Aca- 

 demy of Sciences at Stockholm, for the year 

 1752-, as alfo by Dr. Lewis, in the Philofo- 

 phical Tranfaftions for the year 1754, vol. 

 xiviii. And though theie two gentlemen 

 agree in the principal circumftances relating 

 to this metai, yet it is very plain by their 

 defcriptions, that neither of them knew any 

 thing of the other's experiments. By theie 

 defcriptions we are convinced of the refem- 

 blance this metal bears to gold \ and there- 

 fore we muft allow it to be called white gold, 

 though, both theoretically and practically, it 

 may be diftinguifhed from gold by the fol- 

 lowing qualities. 



1. It is of a white colour. 



2. It is fo refractory in the lire, that there is 

 no degree of heat yet found by which it 

 can be brought into fufion by itfelf, the 

 burning-glafs excepted, which has not yet 

 been tried. But, when mixed with other 

 metals, and femi-metals, it melts very 

 eafily, and especially with arfenic, both in 



its 



