\ 



from the Pyrites. 30 j 



readily fall to pieces crofs-wife, as in the direction 

 of the radii ; and in thefe fiffures, the air infi- 

 nuates itfelf to the heart of the pyrites-globe. 



This alfo may ferve to account for the refolu- 

 tion of the fecond queftion : it is true, the air firft 

 acts, or rather falls upon the pyrites externally, 

 but it acls mod powerfully, when in a proper 

 place, and at undifturbed reft ; both which it finds 

 in the centre of a round pyrites, which is in and 

 about the centre, if not quite hollow, yet of a po- 

 rous texture : whence the clofer a pyrites-body is, 

 with more difficulty does the air not only force into 

 it, but the lefs of it can be collected therein. And 

 hence a piece of pyrites, which is now no longer 

 a whole, nor thus to vi trio life from within outwards, 

 but to be corroded externally by the air, does in 

 the open air and laid naked there, vitriolife with 

 difficulty, or not fo quickly, as when laid in a 

 heap, and thus lying at reft, and in fome mea- 

 fure warm : and thus the innermoft receffes of 

 fuch pyrites become impregnated with vitriol ; 

 which burfts out by breaking afunder its fhell. 

 Neverthelefs, when fuch round pyrites, as ftill lie 

 in the earth, muft vitriolife, they fall not afunder 

 in fuch pieces, but remain entire, notwithftanding 

 which they part with their vitriol, either by an eva- 

 poration, exficcation, and a reduction to an earth, 

 by an unobferved elixation, though I fufpect the 

 former rather than the others •, thus they exhibit 

 themfelves internally neither pyrity nor vitriolic^ 

 but like a brown, yellowifh, rufty iron-ftone, or 

 an iron-earth firmly baked together ; as in parti- 

 cular may be feen from periwinkles, and mufcles, 

 exhaufted of their pyrity fubftance ; which in their 

 fhells, ftill really exifting, though generally cal- 

 cined* 



