in the P yri t e s. 119 



iron-regulus, and to pyrites, where the copper mewed 

 itfelf bodily by the common proof, without the 

 trouble of torturing with vinegar, fefa Laftly, I 

 proceeded with them in the way of a vitriolifation, 

 both by means of the air and fire, oppofmg fuch vi- 

 triol to a pure martial fort, made by art trom iron 

 by means of oil of vitriol ; and thus fufliciently 

 pure from all copper : yet there was no difference of 

 colour obfervable ; though upon tailing it, its 

 naufeoufnefs failed not to manifeft itfelf. But a 

 vitriol, mixed with fome alum, though otherwife 

 entirely free from iron, as is often the cafe of that 

 from fhivery and black kneifs, pyrites-vein- ft one, 

 as is that of Braunfdorff, and the Hungarian native 

 vitriol itfelf, caufes fuch a degree of naufeoufnefs 

 on the tongue, as though it were coppery, that it 

 is no eafy matter to diftinguifn them : as I was long 

 unacquainted with this, I could affirm nothing 

 with certainty about it, but was again obliged to 

 have recourfe to iron, which at length extracted 

 the copper out of fuch vitriols and pyrites, wherein 

 I never fufptcted any fuch thing to be. The me- 

 thod in fhort is, todifTolve the vitriol in common 

 water, and put a polifhed iron wire therein; when 

 the copper, though in the lead quantity pofiible, 

 not only vilibly colours the iron of a copper-red, 

 but alfo crufts it over with a kind of copper fkin, 

 whilft the iron in the mean time confumes away, 

 and partly goes into the vitriol mixture, and partly 

 falls down to the bottom ; and this fo long as there 

 remains the leaft copper therein : {q that this is the 

 bed way of purifying a coppery iron-vitriol, as (hall 

 hereafter appear more at large. 



After premifing in general the yield of other 

 ores, we fhall in particular treat of that of copper. 

 As to the noble metals, gold and filver, their yield 



I 4 in 



