Elements of Mineralogy, 

 32. Mr. Bergman gives the following fhott 

 ingenious method of anaJyling thefe ores in 

 the moift way. 



i* He digefts this compound ore in th 

 marine acid for 24 hours, by which means 

 the vitriol of filver is decompofed, and the 

 whole is converted into horn filver. He 

 then judges of the quantity of the vitriol of 

 filver, by the quantity of vitriolic acid let looft 

 in the liquor, and to find how much this is, 

 he decants the clear liquor, and drops into 

 it a folution of nitrous barofelenite, which is 

 immediately decompofed by the vitriolic acid, 

 and forms true vitriolic barofelenite, of which 

 100 grains contain 15 of dephlegmated 

 vitriolic acid, and fo in proportion* Now 

 100 grains of vitriol of filver, contain 25,37 

 of the fame dephlegmated acid, fo that 25,37 

 grains of this acid, indicate 100 of vitriol of 

 filver, and fo in proportion, and thus the quan- 

 tity of filver in the vitriol of filver is alfo 

 found, as 100 grains of it contain 74,62 of 

 filver,* and the proportion of vitrol of filver 

 being known, that of horn filver of courfe, 

 is known ; but if the ore be of the black 

 kind, after the whole is turned into horn 



filver, it fhould be digefted in cauftic volatil 



, 



* According to Mr. Bergman^ 100 parts of vitriol of filver, 

 contain but 68,75 of filver. 



alkali, 



