the Hefian Pyrites; 357 



then (moll of all, that which refolves the fooneft) 

 heaves or ferments, as it were, from within out- 

 wards, comes to have cracks, and thus gradually 

 falls afunder, and acquires a vitriolic falinenefs. 

 Whence it clearly appears, fuch fermentative, 

 inteftine, dhTolutory motion mud needs originally 

 arife in the very center of the pyrites. In the 

 conchites Uvahkt of Landwernhage, which are ftill 

 covered with their clofe natural fhells, but inter- 

 nally filled with pyrites. I obferved in what; man- 

 ner, fome, before ever any thing vitriolic could 

 be obferved in them, fnap afunder in the middle, 

 and open quite wide, in fuch a manner, as that the 

 hinges, wherewith the fhells ftill remained joined 

 together, ftand directly oppofite to each other, 

 which can be afcribed to nothing but the above 

 mentioned caufe. Further, fome authors have 

 remarked, the fulphur pyrites, both in the groove 

 and elfewhere, when lying moift and heaped high 

 on each other, ufually to heat from within out- 

 wards. And in order to try, whether the fame 

 would not hold of the pyrites of Almerode, I took 

 between 50 and 60 pounds thereof frefh dug, and 

 ftamping them to the fineft powder, I moiftened 

 this powder gently, and (hot it into tall glafles, pre- 

 pared expiefly for the purpofe ; and tho' left (land- 

 ing open for fome time in the free air ; yet it did 

 not difcover the leaft degree of heat or warmth : 

 nay, the pyrites, thus moift and laid high on each 

 other, would not even bewray the lcalt change, 

 or yield the leaft vitriol : whether the time of 

 year, as it happened to be October, was unfit for 

 this experiment, I (hall not pretend to determine. 

 This very experiment 1 repeated in another man- 

 ner, putting fmall powdered pyrites, moiftened 

 with brandy, into a low cucurbit, to which I 

 fitted a large helm and receiver, in no cafe 



to, 



