•'M' Mr Connell's Chemical Examination, of Gteenockite. 



The excess of barytas was then removed from the liquid, 

 after concentration by heat, by sulphuric acid. After again 

 concentrating, carbonate of ammonia was added in excess. 

 The carbonate of cadmium was separated by filtration, and 

 well washed, dried, and ignited. The oxide of cadmium thus 

 obtained had an ochre-yellow colour, and weighed 3.28 grains, 

 equivalent to 2.868 of cadmium. A little of it dissolved in 

 muriatic acid was entirely taken up by excess of ammonia. 



The filtered liquid was then evaporated by heat, but no pre- 

 cipitation had taken place when all smell of carbonate of am- 

 monia had disappeared ; thereby confirming the previous ob- 

 servations as to the absence of zinc. The evaporation was 

 carried to dryness, and the ammoniacal salt driven off by heat. 

 A residue of .04 remained of a reddish-white colour, which, in 

 so far as its small quantity permitted examination, was found 

 to be, in part at least, a subsulphate of iron, insoluble in wa- 

 ter, and scarce soluble even in acids, till previously boiled with 

 potash ; but, as the proportion of its constituents could not be 

 determined on so little material, the iron could not be com- 

 puted in any other way than by stating it as a trace in the 

 mineral, its amount, on any view, being very small ; and if 

 more than such, this was not the stage of the analysis in which 

 it should have been obtained. 



We have thus, in the 3.71 gi'ains of the mineral under ana- 

 lysis. 



Sulphur, . . . .837 22.66 



Cadmium, . . . 2.868 77.30 



Iron, traces. 



3.705 99.86 



which agrees completely with the theoretical composition of 



1 atom Sulphur, . 201.16 22.40 



1 atom Cadmium, . 696.76 77-59 



897.92 99.99 



The mineral is thus a protosulphuret of cadmium, and its for- 

 mula C rfS. It is, so far as I know, the only separate ore of 

 cadmium hitherto discovered. 



It is readily distinguished hy its blowpipe reaction from 

 zinc-blende, the mineral which ranks nearest it in the system. 

 From its decrepitating property, it is difl&crdt to act on it per 



