342 Fads 7ipG7i ivhkh to found a History 



blue; it crystallizes easily ; the crystals arc blue; it is the 

 dc-hydratcd muriate. As soon as it absorbs huniidity it be- 

 comes red. 



The muriatic acid at 15^ yields a great deal oF gas with 

 black oxide. This solution is green while it retains the gas; 

 but as soon as it has lost it, it becomes blue. The blue 

 traits of the muriate of cobalt, dried upon paper, are nothing 

 else than de-hydrated muriate. When they are green, it is 

 because the salt still contains muriate of nickel, which 

 tinges it yellow, and forms green with the blue. 



Its Distillation. — When brought to a red heat in a luted 

 retort, those parts only which touch the glass are decom- 

 posed : the products then are muriatic acid in vapour, mixed 

 with oxygenated acid. The glass is tinged blue. The non- 

 decomposed muriate is sublimed, after being melted in gray 

 flaky flowers ; these undergo a kind of condensation, which 

 renders them insoluble in water for at least 12 hours. Lat- 

 terJy, they give a solution of common muriate. 



Arsenil-c and Arseniatc. — Thearsenite of cobalt is -prepafed 

 bv pouring a solution of cobalt well diluted into a solution 

 of arsenlte of potash. W^ obtain a red precipitate, which 

 preserves this colour upon drying. 



Character of the Ars-cnite, — 1st. Heated in a tube closed 

 at one end, it is decon^posed ; the oxide of arsenic is sub- 

 limed, and the glass is tinged blue. 



2d. The nitric aeid dissolves it, and there is nitrous gas. 

 3d. The nmriatic solution is decomposed bv sulphuretted 

 hydrogen, which precipitates orpiment. 



4th. Pure potash, with the assistance of heat, sets free 

 the blueoxide. 



Arsenlate. — We obtain it by using arseniate of potash in 

 place of arscnite. The precipitate is red, like the arsenitc. 



Characters. — 1st. Heated in the tul>e, it does not give 

 any sublimate; it becomes violet, without tingeing theglass. 

 2d. The nitric acid dissolves it without nitrous gas. 

 Sd. Its muriatic solution is not disturbed by the sulphu- 

 retted hydrogen until two hours after the mixture. 



4th. Pure potash sets inx tlie blue oxide, and is combined 

 with the acid. 



The 



