Greenockite^ or Sulphuret o/Cadmiurm r 89^^ 



ret of cadmium, as the change of colour, by heat, seemedako 

 to indicate. This supposition was confirmed on finding that 

 the precipitates by potash, and by carbonate of ammonia, were 

 not dissolved by excess of the precipitants, and that sulphu- 

 retted hydrogen threw down, from a muriatic solution, with 

 excess of acid, a fine yellow precipitate. After the current of 

 sulphm-etted hydrogen no longer caused a precipitate, the solu- 

 tion was neutralized by ammonia, when a few dark flocks of 

 sulphuret of iron fell. The current of sulphuretted hydrogen 

 was then x-emoved, but no farther precipitate was occasioned ; 

 shewing the absence of zinc, a conclusion farther confirmed 

 by finding that the excess of potash, and of carbonate of am- 

 monia, used as precipitants, took up nothing. The mm-iatic 

 solution of the mineral farther gave a yellow precipitate with 

 hydrosulphuret of ammonia, and white precipitates with prus- 

 siate of potash, oxalate of ammonia, and phosphate of soda, ' 

 and no precipitate with sulphuric acid. A piece of zinc threw 

 down reduced metal as a grey ramification. ; -n 



These various reactions left no doubt that the mineral womz 

 der examination was sulphuret of cadmium, that it containesia 

 no zinc, and that the only impm-ity which could be detected - 

 was a slight trace of iron. The observations were farther 

 confirmed by comparative trials made on a solution of metal- 

 lic cadmium. 



I was indebted to Lord Greenock for a crystal of the mi- 

 neral sufl&ciently large to enable me to take its specific gravity, 

 and also determine the proportions of the constituents. The 

 specific gravity of this crystal was found to be 4.842 at 60° F 

 Previous to analysis, the dark and opake portions were se- 

 parated." .;■ '"'''^"^ 



3.71 grains of the transparent portion of the mineral were 

 reduced to somewhat coarse powder, and fuming nitric acid 

 was poured on them drop by drop in a deep flask, and the 

 whole digested with excess of acid, till all the sulphur which 

 had separated was dissolved. Water was then added, and the 

 sulphuric acid thrown down by muriate of barytes. The sul- 

 phate of barytes, after being well washed with hot water, was 

 dried and ignited; and weighed 6.07 grains, equiyaleAt. jtp 

 .837 grains of sulphur. 



