322 Elements of Mineralogy. 



gives fire with fteel, it does not decrepitate 

 nor fmoke when heated, yet it lofes about 13 

 per cent, of its weight by torrefadtion. 



loo Parts of that of Sahlberg, contained by 

 Mr. Bergman's analyfis, 44 of zinc, 5 of 

 iron, 1 7 of fulphur, 5 of water, 5 of argill, 

 and 24 of quartz. 



20. In analyfing this ore, the water and 

 fulphur were obtained as before, nitrous acid 

 was feveral times diftilled to drynefs over the 

 refiduum, which was at laft calcined, and 

 again treated with the nitrons acid, which 

 then left the iron and quartz and a little 

 argill undiffolved ; the Pniffian alkali preci- 

 pitated the zinc from this folution, and after 

 that, the aerated volatil alkali precipitated 

 the argill. The undiffolved refiduum was 

 treated with oil of vitriol diftilled to dry- 

 nefs, which took up the calx of iron, and a 

 fmall proportion of argill. The Prujfian alkali 

 precipitated the iron, and the liquor being 

 then evaporated, afforded a little alum and 

 tartar vitriolate. 



IV. VARIETY. 

 Phofphorefcent Blende. 



21. Its colour is generally greenifh, yel- 

 -lowifb green, or red, of different degrees of 



tranfparency, 



