Silver. 245 



cific gravity is from 5,4 to 5,684. Mr. 

 Bergman found 100 gr. of it to contain 60 

 of filver, 27 of arfenic, and 13 of fulphur. 

 2 Bergm. 303. but fometimes it contains 

 even 70 per cent, of filver. The darkeft ores 

 are the richeft, and thefe often contain a little 

 iron ; the yelloweft are the pooreft > the moft 

 yellow does not belong to this fpecies, being 

 in fat orpimeat, containing 6 or 7 per cent* 

 of filver. 



14. To analyfe this ore in the moift way, 

 Mr. Bergman advifes to boil it after it is re- 

 duced to a very fine powder in dilute nitrous 

 acids, asinN 8, and to edulcorate the refi- 

 duum very carefully which contains the ful- 

 phur and arfenic, which may be feparated by 

 boiling in a fufficient quantity of aqua regia : 

 if the fulphur ftill retains any luna cornua, it 

 may be feparated by cauftic volatil alkali. 



15. In the dry way it is reduced after tor- 

 refaftion by a mixture of iron and lead ; the 

 iron takes up the fulphur, and the lead the 

 filver, which is afterwards feparated by cup- 



pellation. 



R 3 SPECIES 



