On a New Mineral from M'lvor. 19 



filtering, the residue (freed of the flocky sulphur) proved to 

 be sulph. lead, with a trace of antimony. Here the fact 

 was to be observed, that after the chief part of the solution had 

 passed through the filter, and water was poured on it for 

 washing the residue, the fluid received a milky appearance. 

 As this is a proof of the presence of either antimony or 

 bismuth, the white milky precipitate was filtered, and 

 brought together with tartaric acid, it dissolved very easily, 

 and gave thus a doubtless proof of the absence of bismuth, 

 and the presence of antimony. 



" The filtered fluid was now acted upon by sulphohydric 

 acid; a black precipitate resulted, which, after careful 

 washing, was brought together with sulphodydride of am- 

 monia, and heated. As no perceptible change in colour or 

 quantity of the precipitate took place, the fluid was, however, 

 filtered, and chlorohydrip acid added to it, the forthcoming 

 greyish orange-coloured precipitate fstill in very small 

 quantity) proved now the presence of antimony without a 

 doubt. The black precipitate, dissolved in nitric acid, to a 

 green solution (Cu.), by parting with flocky sulphur. Sul- 

 phuric acid caused now a white heavy precipitate of sulphate 

 of lead ; and ammonia in excess, added to the liquor (filtered 

 from pulphate of lead) imparted a light blue colour — no 

 precipitate — testing so the presence of copper, however small 

 in quantity, and the absence of bismuth and cadmium. 



" The fluid, filtered from the black precipitate, caused by 

 sulphuretted hydrogen, was mixed with ammonia, and chlo- 

 ride of ammonia, till it rendered red litmus paper blue, and 

 then sulphohydride of ammonia added and no precipitate 

 appearing proved the absence of iron, nickel, and cobalt. 



" The final result of this qualitative anaylsis can now be 

 stated as follows : — 



" Lead and sulphur form the predominant components ; 

 copper and antimony are present in small quantities. 



" As the specimen of the ore was very small, and much 

 impregnated with quartz, a larger and purer piece, perhaps 

 with crystals or cleavage observable, would be very satisfac- 

 tory, and enable one to make an exact quantitative analysis to 

 establish the fact of its being a new mineral, which most of 

 the results of the above recorded experiments tend to. 



" It need not be added that a trace of silver is not excluded 

 by this analysis, and could in a purer piece be easily found 

 by smelting, and afterwards cupellating with a portion of 

 test lead. Most of these minerals contain a trace of silver." 



c2, 



