from the Pyrites^ 331 



and of falts into earths, and of thefe laft among 

 themfelves; namely, that fatty, black, grey, ihi- 

 very, unctuous earth and ftone, eminently break- 

 ings by pyrites^ and from which alum is ufually 

 produced, and thus probably of a luty, flimy ori- 

 ginal. 



Amidft certain circumftanees, efpecially as foon 

 as fuch earth, procured from fuch ftone, is laid 

 hold on by the vitriol -acid * or rather, as foon as 

 the acid in this ftone itfelf comes to work ; or 

 more properly (till, as foon as this ftone comes to 

 act upon itfelf (whereby not only the vitriol- acid 

 by the attraction of the air, but alfo the aluminous 

 earth is formally made ; in fhort, the alum pro- 

 duced not only in its whole, but its parts) there 

 indeed fuch ftone cannot arrive to the aicaline earth 

 we are here in queft of, as in this production in 

 general, not proving faline, but ftubborn, calca- 

 rious, or highly cretaceous. And yet, what is this 

 more than a converfion ? But, when the vitriol-acid 

 comes not thus in play, as we may learn from the 

 alcali lying quite naked and unfaturated in acidulx^ 

 and thence coming to ferment with acids, there 

 indeed the circumftanees, confequently the diffe- 

 rence cannot minutely be made out, but muft be 

 charged to the fcore of the difference of elabora- 

 tion, and other incidental circumftanees : fo alfo 

 fuch ftone exhibits not its habitude to acid, but 

 fomething, namely, the alcali, according to ap- 

 titude rather peculiar than incidental to it. In fhort, 

 let this ftone be properly burnt, and the alcali, tho* 

 in a very fmall quantity, will become manifeft not 

 only from its habitude to acid, but alfo from the 

 actual exhibition of a bitter fair. 



But 



