of Mineral Substances. 275 



of sulphur were acidified by the nitric acid : if to these we add 

 the above seven grains which were burned, and estimate that 

 lost in the sulphuretted hydrogen as equal to 0.25 grains, the 

 proportion of sulphur in the ore may be considered as = 13.75 

 grains, per cent. 



C. a. 1000 grains of the ore were gradually heated to red- 

 ness in a retort connected with the pneumatic apparatus ; after 

 the expulsion of the atmospheric air, 34 cubic inches of sul- 

 phuretted hydrogen were evolved, besides a portion absorbed 

 by the water. 



b. The receiver contained some globules of mercury : the 

 neck of the retort contained a mixture of moist black sulphuret 

 of mercury, globules of metallic mercury, and some particles of 

 cinnabar; the mercury, mechanically separable, weighed 317 

 grains. In the upper part of the neck of the retort was a com- 

 pact sublimate of pure cinnabar, weighing 236 grains. 



c. There remained in the retort a light black powder, weigh- 

 ing 39 grains, which, after incineration upon a capsule, left 16 

 grains of a brownish grey, earthy powder ; hence the portion of 

 burned carbonaceous matter may be considered as ::^ 23 grains. 



d. This earthy residue was digested in muriatic acid ; there 

 remained silica weighing, after having been ignited, 6.5 grains. 



e. The muriatic solution, which was of a greenish colour, was 

 supersaturated by ammonia, which produced a brown precipi- 

 tate, leaving the supernatant liquid of a pale blue colour. The 

 precipitate was digested in hot solution of potash, and there 

 remained oxide of iron, which having been brought to the mag- 

 netic state, weighed two grains. 



f. Muriate of ammonia being added to the alcaline liquor, 

 alumina was precipitated, weighing, after having been ignited, 

 5.5 grains. 



g. The ammoniacal liquor, after supersaturation with muri- 

 atic acid, afforded upon a piece of immersed zinc, 0.20 grains 

 of metallic copper. 



From the above experiments it appears, that 1000 parts of 

 the compact hepatic ore of mercury from Idria contain 

 Mercury . .A. . .818. 



Sulphur . B. 6 . . 137. 50 



