316 The Vitriol 



joining and interfperfed mineral, and thence 

 exhibit alum. We purpofely omit mentioning 

 why fuch vitriolic, aluminous lies now fhoot firft 

 to alum, and that per fe, without a precipitant, as 

 happens in thofe of Braunfdorff •, again, why to 

 vitriol firft, and then to alum, not eafily without 

 a precipitant; and how alum, made per fe, differs 

 from that made with addition, as fometimes of 

 urine, then pot afh, then quick- lime, and fome- 

 times of fpirit of urine ; and the rather, as we ex- 

 pect a particular differtation on the fubjedt of alum 

 from profeffor Baier, at Altorff. 



An earth here difcovers itfelf, which is fome- 

 times grey, fometimes yellow -, the former called 

 Jlime, the latter, ochre: the flime is procured not 

 fo much from pyrites, as from the earth inter- 

 mixed and incorporated with it *, though whether 

 fuch earth be ever procurable from the mixtion of 

 the pyrites itfelf, a thing I could never find, de- 

 ferves examination ; the ochre, on the contrary, 

 appearing of a brown-yellowiffi, alfo of a rufty 

 carl, and confifting partly of a metallic, fometimes 

 iron, fometimes copper, and partly of an unme- 

 tallic earth, is more certainly derived from the py- 

 rites, though not immediately, but mediately only, 

 by means of the vitriol, to which the pyrites muft 

 be firft reduced. It is found not only near and 

 upon crumbled mixt-work, but warned away by the 

 waters, in what is called the gurs, or metallic 

 juices, and deferves a peculiar regard ; as does alfo 

 that fulphur-yellow earth, precipitated in boiling 

 for vitriol, and burnt to a red colour, yet not 

 to be confounded with the ochre, being not only 

 brighter, but alfo fomething more than a pure 

 earth, namely, ftill confiderably vitriolic and alu- 

 minous. 



There 



