295 



strong smell of sulphuretted hydrogen ; and the solution by evapo- 

 ration affords a crystallized salt, not deliquescing in an ordinary 

 atmosphere. Carbonate of soda causes in the solutiop a white 

 precipitate, dissolved on adding ammonia. The precipitates by 

 potash and by carbonate of ammonia are not dissolved in whole 

 or in part by excess of the precipitants. Sulphuretted hydrogen 

 throws down from the solution with excess of acid, a copious yel- 

 low precipitate ; and after neutralizing by ammonia, during which 

 operation a few flocks of sulphuret of iron fall, a renewal of the 

 current of sulphuretted hydrogen causes no farther precipitation. 

 Oxalate of ammonia, phosphate of soda, and prussiate of potash, 

 cause white precipitates ; and sulphuric acid does not occasion 

 any at all. A piece of zinc throws down reduced metal as a grey 

 ramification. These various reactions sufficiently prove that the 

 mineral under examination is sulphuret of cadmium ; and that it 

 contains no zinc, and only a trace of iron. 



" The author having obtained a larger crystal, of a reddish-yel- 

 low colour, and of similar crystalline form, from Lord Greenock, 

 found its specific gravity to be 4.842 at 60° F. An analysis was 

 also effected on 3.71 grains, principally of this crystal, by decom- 

 posing it by fuming nitric acid ; precipitating the sulphur in the 

 state of sulphuric acid by muriate of barytes ; and throwing down 

 the excess of barytes by sulphuric acid, and the cadmium as a 

 carbonate by carbonate of ammonia, and converting it into the 

 oxide by ignition. The constituents were thus found to be : 



Sulphur, . . 22.56 



Cadmium, . . 77.30 



Iron, traces. 



99.86 

 Agreeing completely with the theoretical composition of 

 1 Atom sulphur, . 201.16 22.40 



1 Atom cadmium, . 696.76 76.59 



897.92 99.99 

 The mineral is thus a protosulphuret of cadmium, and is the first 

 instance of a separate ore of cadmium, so far as the author knows. 



" It is readily distinguished from transparent yellow zinc-blende, 

 which it resembles, by its orange streak, that of yellow zinc- 

 blende being white, and by its yielding with soda before the blow- 

 pipe a copious yeUowish-red ring of sublimated cadmium, with 

 no white sublimate. With borax it gives a yellow gloss. 



" The specific name of Greenockite has been given to it by Pro- 

 fessor Jameson, in honour of Lord Greenock." 



