324 ffi* Vitriol 



ncous fuming and frothing, and turning, after ex- 

 ficcation, fmeary in the air, like an alcali. 



Whatever be in that, thus much we know, that 

 this vitriolic refidue confifts of two parts, namely, 

 the vitriol-acid^ and an earth, as appears by an en- 

 tire expulfion of the acid, by means of a thorough 

 glow-, whence it feems that thefe two parts were 

 but {lightly combined, confequently, that they can- 

 not conftitute a genuine alcali, as from fuch the 

 vitriol-acid can never be expelled per fe : but again, 

 there mull alfo be an earth, without which no exfic- 

 cation can be procured •, and he who confiders, or 

 rather, manually treats falts, with refpect to their 

 productions, tranfmutations, origination from, and 

 reduction, to earth again, will find fuch phenomena 

 exhibited from a vitriol- acid^ and an earth ; though 

 he may be unable to affign the formality, or remote 

 caufes, which generaliy lie concealed from us in 

 other inftances. 



That this earth is from iron feems probable ; for 

 to what Homberg -f has remarked of an iron fatti- 

 , nefs exhibited by means of a burning-glafs, and 

 -what others credibly relate, of a quickfilver from 

 iron, Dr. Rothe has added fome weight, in his dif- 

 fertation on metallic falts : not that 1 would afcribe 

 any thing peculiar to iron before other metals, as 

 it is a fort having only proximately its origin from 

 a ciude unmetallic earth, and with which, as one 

 of the coarfeft, earthy metals, many things may 

 chance to be incorporated, 



A brown-red earth, called caput mortuum, re- 

 mains behind from vitriol-lies ; but then only to 

 be fo denominated, when no longer containing any 

 thing living and pungent, i. e. faline and fapid j 



cottr 



f Mem. Tan. 1710, p. 303, 



