54 Elements of Mineralogy. 



for loo parts of it contain 65 of pure 

 Earth, 28 of water, and 7 of the aerial acid ; 

 whereas 100 parts of the native contain about 

 20 of aerial acid and 78 of Earth, a little of 

 the vitriolic barofelenite, and no water. It 

 effervefces with acids. 



The artificial, when calcined, burns to lime, 

 which, has the properties of pure barofelenite 

 already defcribed ; but the natural will not 

 burn to lime, for it will not part with its 

 fixed air, but rather melts, as Dr. Withering 

 has difcovered. He alfo found that cauftic 

 alkalis precipitate this Earth from the nitrous 

 and marine acids, which happens, as I think, 

 from their taking up the excefs of acid requi-* 

 fite to keep it in folution. 



SPECIES II. 

 Combined with the 'vitriolic Acid. 



Barofelenite^ Mar m or Met alii cum, Cronff. 182, 

 Lapis Bvnonievfis, Selenitic t Spar, Gypfum 

 Spathofum^ Spat hum Fnflbile^ Margraf 2, 

 Theile p< 44, Weigel ferv< Mineral^. 65 

 and 66. Ca<wk 9 Petunje of fome, Ponderous 

 Spar. 



This ftone is of a white, grey, or yellowilh 

 white colour, and fometimes reddifh ; fome- 



times. 



