in the Pyrites, tzg 



down the weight of the gold procured ; alfo, that 

 he does not inform us, whether the procefs was car- 

 ried on with the fame parcel of filver, and with 

 the fame yield over and over ; though this cannot 

 be, at leaft, feems not credible, as may appear from 

 his fecond experiment, which mall be mentioned 

 below, and as may be concluded from his judge- 

 ment on it ; and Jaftly, we have not Homberg's 

 purfe, for repeating fuch experiments. We may, 

 however, firmly rely on his veracity, and conclude 

 from this, how much reafon we have, even in fuch 

 mineral and metallic proccff-- as happen per [e, to 

 expect new forms and productions. 



For, in the experiment before us we have no 

 ore, but a fimple, and every way well parted me- 

 tal ; no compound, but a mixt. Here we have nei- 

 ther fulphur nor arfenic, as is in pyrites, nor lead, 

 nor any thing elfe added : yet, how fimple foever Ri- 

 ver may appear, it is not really fo ; it ought to be 

 obferved, as appears from Homberg's fecond ex- 

 periment, that the whole of the filver is not con- 

 verted to gold, but only fome particles, which have 

 their certain number, weight, and meafure, and are 

 produced all, if not at the firft, yet at the fecond 

 and third trials. And what is it in filver, which 

 thus is no filver? probably an earth. 



A foreign metallic earth may be contained, to a 

 confiderable quantity, in filver, as may be judged 

 from the univerfal mercurial affinity of metals, and 

 particularly of iron-earth, which, notwithstanding, 

 cannot efcape depart-waters, and often proves to be 

 that fallacious black calx, which we take for a gold* 

 ca.x, though in fact it is no fuch thing : and if this 

 earth, which turns to gold, be an iron-earth, may- 

 no: the like, with more probability, be fuppofed in 



Q^ 3 pyrites- 



