394 Intelligence and Miscellaneous Articles. 



precipitate obtained from permuriate of mercury in excess^ is 



formed of Mercury 81"80 



Chlorine 953 



Sulphur 8-67 



10000 



M. Rose remarks, that these proportions are equivalent to 1 atom 

 of chloride of mercury and 2 atoms of sulphuret of mercury ; but 

 they are not reducible to this composition, employing the numbers 

 generally adopted in this country. 



This compound, prepared by passing sulphuretted hydrogen into 

 a solution of permuriate of mercury, remains long suspended, and 

 forms an emulsion, which filters with great difficulty. It is better 

 to boil black sulphuret of mercury, while moist, with permuriate of 

 mercury ; but it must be left for some time that it may filter readily. 

 The white precipitate dries perfectly well ; when exposed in a tube 

 to heat, it is decomposed, and perchloride of mercury is sublimed ; the 

 sulphuret of mercury is volatilized rather later. That the separation 

 of these substances may be perfect, it is necessary not to heat, them 

 too quickly ; the white precipitate is insoluble even in concentrated 

 acid, but is rapidly acted upon by aqua regia : when heated in a 

 tube and exposed to chlorine, chloride of sulphur is first obtained, 

 and afterwards perchloride of mercury. Caustic alkalies gradually 

 blacken it ; even in the state of carbonates an alkaline chloride is 

 formed, and the oxygen of the alkali takes the place of the chlorine ; 

 but the oxide of mercury remains in the state of mixture with the 

 sulphuret. 



Analogous phaenomena occur with the perbromide, periodide, 

 and perfluoride of mercury: the compound bromide and sulphuret 

 of mercury was obtained by digesting sulphuret of mercury in a 

 solution of perbromide ; it is of a yellowish white colour : by 

 heat it is decomposed into bromide of mercury, which volatilizes 

 first, and sulphuret of mercur}', which sublimes afterwards: it 

 is composed of 1 atom of perbromide, and 2 atoms of sulphuret 

 of mercury. 



Periodide of mercury treated with sulphuretted hydrogen gives a 

 yellow precipitate, which remains suspended, and is easily separated 

 from the iodide in excess ; by heat it is decomposed into periodide 

 and sulphuret of mercury. 



Perfluoride of mercury similarly treated offers analogous results : 

 by treating a solution of peroxide of mercury with excess of fluoric 

 acid, a white precipitate is obtained, which when washed and dried 

 so as to deprive it of all water, becomes yellowish, which colour it 

 loses on regaining water : it is decomposed by boiling water. 



The solutions of mercury in all acids give precipitates with sul- 

 phuretted hydrogen, which contain a portion of the solvent acid ; 

 the only one analysed was obtained from pernitrate of mercury. 

 It consisted of 



Sulphuret of mercury 58-95 



Pernitrate of ditto 41-05 



100-00— i5»/. xl. 46. 



SALTS 



