C58 MERCURY. 



the amide of potassium, when ammonia escapes, a compound 

 of nitrogen and potassium, NK 3 .* 



When white precipitate is boiled in water, it is changed into 

 a heavy canary yellow powder, which Dr. Kane has shewn to 

 be a compound of the double chloride and amide of mercury 

 with oxide of mercury, Hg Cl + Hg, NH 2 + 2HgO. Two atoms 

 of water are decomposed in its formation, the two atoms of oxy- 

 gen which are found in the yellow compound, while the two 

 atoms of hydrogen, added to an atom of chlorine and an atom 

 of amidogen, form an atom of hydrochlorate of ammonia which 

 is found in solution : 



Solutions of potash and soda convert white precipitate into 

 the same yellow substance, while a metallic chloride is formed 

 and ammonia evolved (Kane). 



Oxichloride of mercury. When a solution of corrosive subli- 

 mate is precipitated by potash or soda, mercuric oxide goes 

 down in combination with a portion of chloride, as a brown 

 precipitate, unless a considerable excess of alkali be employed. 

 The same oxichloride is produced by an alkaline carbonate, but 

 a double carbonate is then also formed. Chloride of mercury 

 is not immediately precipitated by the bicarbonates of potash 

 and soda, and, hence, that salt may be employed to detect the 

 presence of a neutral alkaline carbonate in these bicarbonates. 

 This oxichloride may also be formed by passing chlorine through 

 a mixture of water and oxide of mercury. It may be obtained 

 crystalline and of a very dark colour, almost black, by mixing 

 corrosive sublimate with chloride of lime, and boiling the liquid, 

 or by treating a solution of corrosive sublimate with bicarbonate 

 of potash, and allowing the solution to stand in an open vessel, 

 when carbonic acid gradually escapes, and the compound 

 HgCl + 4Hg O is deposited. This oxichloride is decomposed by 

 a moderate heat, chloride of mercury sublimes and the red 

 oxide is left. 



Chloride and sulphuret of mercury, Hg Cl-|-2Hg S. When 

 sulphuretted hydrogen gas is passed through a solution of chloride 

 of mercury, the precipitate which first appears, and does not 

 subside readily, is white; it has been shown by Rose to be a 



* Mitscherlich in Poggendorff s Annalen, vol. 39, p. 409. 



