1820.] Dr. Clarke on Cadmium. 273 



by fracture and fiiction. It filled the whole house. Placed in 

 strong muriatic acid, and the acid boiled, a solution took 

 place, but Avithout any rapid or vehement action, sulphur- 

 etted hydrogen being evolved as before. The solution was 

 then evaporated to dryness, and distilled water being added, 

 the whole of the muriates were taken up, no hud being 

 present for separation ; but there remained undissolved a small 

 portion of glittering heavy white particles, which, when col- 

 lected on a filter and dried, weighed nine-tenths of a grain. 

 These particles being examined with a lens were as diaphanous 

 as the most limpid rock crystal. They proved to be diapha- 

 nous quartz in the arenaceous form : some of them had the 

 rounded botryoidal appearance o( Saiitilite ; others were angular 

 and polygonal. 



(B.)^rhe filtered liquor collected from (A.) yielded an orange 

 or orpiment-colourcd precipitate to sulphuretted hydrogen ; also a 

 lohite precipitate to hifdrate of potass, which was redissolved by 

 adding hi/drate oj' ammoida. 



(C.) The same orange-coloured precipitate from (B.) being 

 redissolved in muriatic acid, and the acid evaporated and distilled 

 water added, carbonate of ammonia was poured into the solution 

 in excess, which, holding the zinc in solution, threw down a 

 white precipitate ; and this changed yellow in drying by the loss- 

 of a portion of its carbonic acid. 



(D.) The precipitate from (C.) being redissolved in muriatic 

 acid, and the excess of acid driven off, and distilled water added 

 as before, yielded an orange-coloured precipitate to sulphuretted 

 hydrogen, distinguishing it from zinc; also to phosphate of soda, 

 instead of the crystalline flakes or scales which zinc exhibits, it 

 yielded a white pulverulent powder, which was redissolved in 

 liquid ammonia. It was, therefore, carlxniate of cadmium. It 

 was moreover insoluble in water. But in drying the muriate of 

 cadmium, if too much heat be applied, the salt is decomposed, 

 and the oxide with a beautiful orange colour separates in an 

 insoluble form simply by adding water. 



A stick of zinc of a cylindrical form, being placed in the 

 diluted muriate mentioned in (A.) became coated over with a 

 precipitate which had a dendritic appearance. When examined 

 with a lens, minute metallic scales of a leaden aspect were dis- 

 cernible. Having collected this precipitate by zinc into a watch- 

 glass, and washed it, and evaporated the supernatant Jiuid, the 

 residue appeared, a brown-coloured substance, which powerfully 

 attracted moisture. Having exposed it almost to a red heat, it 

 yet deliquesced in the instant of its cooling. Scraping off some 

 of this on platinum foil, and heating it with the blow-pipe, it 

 sent off white fumes; then intumesced, and exhibited u dark- 

 brown, slag-like, substance, which, by further exposure to heat, 

 Wds converted into an rirange-coloured oxide ; and this agani by 

 alternately applying the point of the blue or the yellovr 



Vol. XV N'= IV S 



