Lead. 



is generally very fmall. Dr. Watfon remarks, 

 that the ores which are pooreft in lead, are 

 often the richeft in filver. <Mr Monnet af- 

 ferted, that fulphurated lead ores are infoluble 

 in nitrous acid, but Dr. Watfon has {hewn that 

 dilute nitrous acid diflblves them compleatly, 

 3 Wats. 228. The fpecific gravity of Galena, 

 is from 7,000 to 7,780 ; when melted it 

 yields a yellow flag. 



14. To analyfe this ore in the moift way, 

 let it be diffolved by boiling in the dilute 

 nitrous acid, the fulphur and infoluble ftony 

 parts and calx of iron will remain undiflbl- 

 ved ; the iron may be afterwards feparated 

 by digefticn in marine acid, and the fulphur 

 by digeftion in cauftic fixed alkali, the refi- 

 duum weighed before and after will mew the 

 proportion of each, 



15. The nitrous folution will contain the 

 lead and filver ; this folution ihould be pre- 

 cipitated by the mineral fixed alkali, and the 

 precipitate wafhed in cold water, dried and 

 weighed. After weighing it mould again be 

 digefted in cauftic volatil alkali, which will 

 diflblve and take up only the calx of filver, the 

 refiduum being again dried and weighed, gives 

 the proportion of the calx of lead, of which 

 132 gr. are equivalent to 100 of lead in its 

 metallic ftate ; and the difference between the 



weight 



