from the Pyrites; 321 



up in the courfe of the fermentation : and laftly, in 

 regard to the caufality of this alcaline vitriol-liquor, 

 he explains himfelf in fuch a manner, as would 

 make one imagine a tranfmutation of the vitriol- 

 acid ; but he does not lay, at leaft not diftinclly 

 enough, whence the matter is derived, which we 

 muft doubtlels fuppofe, for the exhibition of a dry 

 lixivious, and the incorporation of the acid fait. 



That the acid fait of vitriol mould become, I 

 will not fay alcalifed, yet changed fo as to lofe its 

 nature and effcnce, appears, among other inftances, 

 from dlftilling oil of vitriol upon quicklime, when 

 there arifes a mafs that entirely turns moift in the 

 air : but even hence we fee there is fomething which 

 deflroys not only the mixtion of the acid vitriol- [alt : , 

 but mull: alfo give it a body. In fhort, this change 

 cannot happen without fome concurring caufe, and 

 what is here procured cannot properly be held for a 

 changed vitriol-fall, but for a third thing, fomething 

 which muft take its rife from the two other, name- 

 ly, the acid fait, and an earth. 



To give my own thoughts upon this fubje£f,, we 

 are to obferve, firft, that fuch foluble, vitriolic re- 

 mainder fhews itfelf on three different occafions ; 

 ( £.) upon the lixiviation and elaboration of the vitriol 

 from its crude ore; (2.) upon the re-folution and 

 cryftaliifation of a purified vitriol, already feparated 

 from ics ore ; (3.) in the ufual way of preparing 

 vitriol with iron and oil of vitriol. 



The fecond is what gave occafion to M. Geof T 

 froy's remarks, but which I muft pafs over. The 

 firft, of which he makes no mention, is properly 

 within my province, as relating to the vitriolijation, 

 consequently the hiftory of the pyrites. The third 



Y I have 



