47^ Intelligence and Miscellaneous Articles. 



gray. It scratches calcspar, and is scratched by a steel point. Its 

 density is 5*950. When heated on charcoal, it decrepitates, and 

 quickly fuses at a temperature below incipient redness, emitting a 

 sulphurous smell and white vapours. After long-continued roasting, 

 it leaves a globule of silver surrounded by a yellow aureola, indi- 

 cating the presence of oxide of lead. When heated in a close glass 

 tube, it decrepitates, fuses, and yields a small orange-red sublimate, 

 surmounted by a white sublimate. If heated in an open glass tube, 

 it decrepitates, fuses, disengages a strong sulphurous odour, and a 

 white sublimate of peroxide of antimony is deposited on the sides of 

 the tube. 



Concentrated nitric acid attacks it rapidly, with the evolution of 

 nitrous vapours ; the silver dissolves, and a residue is left, formed of 

 sulphur, oxide of antimony and sulphate of lead. Nitric acid, 

 diluted with four times its volume of water, attacks it slowly, 

 evolving sulphuretted hydrogen; the silver and lead are partially 

 dissolved ; a gray deposit is left, in small needles, consisting of sul- 

 phuret and oxide of antimony, containing a considerable portion of 

 lead and silver. 



Hydrochloric acid, when concentrated and boiling, dissolves this 

 substance completely, evolving sulphuretted hydrogen. On cooling, 

 the solution becomes turbid, and deposits chloride of silver mixed 

 with chloride of lead. 



A boiling solution of caustic potash attacks this mineral when 

 finely pulverized. It thus dissolves a large quantity of sulphuret of 

 antimony; a black heavy powder remains, which consists of sul- 

 phuret of silver and lead containing some antimony. 



If sulphur be added to the potash solution, the greater part of 

 the antimony may be separated by successive decantations ; the 

 author, however, never succeeded by this method in separating the 

 sulphurets of lead and silver perfectly from the sulphuret of antimony. 



The analysis of the mineral was performed by acting upon it with 

 a current of dry chlorine, in the manner described by M. Rose. 

 The volatile chlorides of sulphur and antimony were separated by 

 exposure to a gentle heat from the fixed chlorides of silver and lead. 

 The sulphur was converted into sulphuric acid, and its quantity de- 

 duced from that of the sulphate of barytes which it yielded ; the 

 antimony was precipitated by sulphuretted hydrogen ; the sulphuret 

 obtained was analysed by the direct determination of the sulphur, 

 and inferring the antimony. 



The fixed chlorides were treated with boiling water, which dis- 

 solved the chloride of lead ; the chloride of silver remained insoluble ; 

 its weight indicated the proportion of silver ; the chloride of lead 

 was converted into sulphate, and the weight of it gave that of the 

 lead. 



The liquor separated contains a minute quantity of copper, iron 

 and zinc, the quantity of which was ascertained by the usual pro- 

 cesses. 



The mean of three analyses gave — 



