308 Ihe Vitriol 



fettle a little, or otherwife evaporate, let them Fall 

 again, either in icicles, from the roof and fides of 

 levels \ whence we muft make fome diftinction be- 

 tween grown, or native vitriol, as fpontaneoufly 

 produced from pyrites, namely, between that fore 

 formed barely by the humidity of the air, without 

 any addition of either day or groove-water, and 

 that other formed by the acceffion of an actual 

 water. The former we are not to expect in the 

 grooves, and 'tis rare that it is grown, though mot 

 on the fpot where found : whence appears the great 

 folly of alchemifts, in that they would employ for 

 their great -work that produced in the grooves by the 

 water of the air alone, a thing quite impoflible. 



For the vitriolifation of pyrites, there are, befides 

 the action of the air, other aiding or concurring cir- 

 cumftances requifite, at lead when it is to be rendered 

 eafier, or to be more fpeedily difpatched. Thofe on 

 the fide of the pyrites itfelf, though indeed only ne- 

 gative, I have already mentioned, and now come to 

 this, namely, that the pyrites muft contain little or 

 no arfenic or copper, nor be of too clofe a tex- 

 ture : to which we may add this conjecture, that 

 the black vein-ftone, or rock, ufually called kneifs> 

 at Friberg, and almoft fhivery, but much blacker 

 and harder than Jhiver, is, if not a co-operating 

 caufe, yet a fign of an eafier vitriolifation ; but as 

 to external circumftances, there are principally 

 three, which facilitate this operation. Firft, and prin- 

 cipally, the pyrites is to be laid together in as large 

 a heap as poilible, and to lie expofed to the wea- 

 ther and fun, nay, in dry weather to be fprinkled 

 with water, as otherwife it cannot heat or work fo 

 well: or, in the fmail way of proof, the beating 

 fmall the ore, the choice of a fit place, as a cellar, 

 or the like warm fituation, and the laying it in a 



powdery 



