j22 The Vitriol 



I have only employed as a kind of auxiliary means 

 towards the difcovery of the caufe of this furprifing 

 vitriolic production. 



And here, to abide by the firft, I have Found, 

 (i.) That all crude vitriol-boilings leave behind a 

 fatty, thick, oleaginous lie, be the pyrites prepared 

 either with or without fire, vitriolifed above or un- 

 der ground, and the vitriol foaked in the earth and 

 ftone, or caked together in the open air. 



(2.) It ferments with alcali falts, and lets fall a 

 bright brown earth, but never with acids. 



(3 J Upon fetting it by for fome months out of 

 the reach of the fire, fomething fhoots from it like 

 fmall crumbly grains, plumofe and aluminous, as 

 was already obferved. 



(4. J But, if the whole be left together to eva- 

 porate, without feparating this matter, it turns 

 thick like a refin, and at laft becomes a grey whi- 

 tifli mafs. 



(£.) In the courfe of the evaporation, which is 

 performed in the foft heat of a ftove, I once ob- 

 served it heave and rife, and the glafs, fcarce a 

 third full, to become quite filled therewith. 



(6.) This grey mafs taken directly, whilft hardly 

 cold, ferments readily with alcali, but in no fort 

 with acid. 



(7,) Even upon expofure in the air, it turns 

 moid and fmeary, exhibiting the fame phenomena 

 with acid and alcali as before. 



(8.) Di- 



