from t/je Pyrites. 311 



and there to lie for fome time. Upon the whole, 

 by means of the air, a frefh pyrites vitriolifes, air 

 plays in amidft the burning of the pyrites, and, 

 Jaftly, exerts its efficacy in the heap, when the py- 

 rites-emh is become unfit for further impregnation, 

 and thrown on the flag-heap, under the name, ca- 

 put mortuum. 



Thus the fire is, in the bufinefs of vitriolifation.^ 

 to be alio confidered as an immanent inftrument, 

 fo far as, in parr, the air is not only infeparably 

 contained therein, but is almoft the very fubftance 

 of fire itfelf-, alio feeing the fatty, phlogiftic parti- 

 cles from wood or coals cannot fail to be commu- 

 nicated ( hence an open-roafted refolves better to 

 vitriol than a clofe defulphurated pyrites) yet here, 

 fire and air are not to be confidered on an equal 

 footing, but fire is alfo to be confidered as a pene- 

 trating, opening inftrument •, particularly as what 

 fits and prepares the pyrites for the action of the air. 

 For, not only the fort in general, which muft un- 

 dergo the torture of the fire, is to receive from the 

 air the true matter of the vitriol, but alfo that 

 which immediately upon burning refigns its vitriol* 

 is afterwards to be committed to the air, in order 

 to a fuller yield. 



Now, all forts of pyrites, whether fpontaneoufly 

 vifnolifing, or prepared for vitrioiifation by the ac- 

 tion of the fire, will take a long time, nay, a courfe 

 of years, before nature has thereby worked them 

 dead, or exhaufted them of their vitriol: but as in 

 the vitriol- huts the waiting fo long would not de- 

 fray the charges, befides, that the vitriol produced 

 d be apt to be warned away by rain and water, 

 or foak into the earth, and there be loft, were we 

 to wait till the visriolifation was fully finilhed ; it 



X 4 is 



