Intelligence and Miscellaneous Articles. 315 



acid and then dried, without suffering any alteration in its colour. 

 But if boiled with this water, it yields protonitrate of mercury, and 

 becomes quite white. If a solution of protonitrate of mercury be 

 poured upon this white precipitate and left at rest on it at or- 

 dinary temperatures for several hours or longer, the precipitate 

 gradually becomes as blue as it was at first ; and after some days the 

 intensity of this colour increases, if the nitrate of mercury remains in 

 excess: if the precipitate be heated with the latter it remains white, 

 but after the evaporation of the water of the nitrate of mercury, it 

 becomes blue, and if the heat be increased, orange red. 



When the blue and orange red precipitate is strongly heated on a 

 piece of platinum foil, it detonates, giving out sparks and smoke, and 

 flying on all sides like sky-rockets, with a hissing noise. It is dis- 

 solved in heated muriatic acid, with the formation of nitric acid and 

 hydrocyanic acid, and forms a colourless solution which is not rendered 

 turbid by alcohol nor precipitated by muriate of ammonia. 



The white precipitate kindles when heated on platinum fod 

 without detonating, burns away without flame, and leaves behind 

 about 38 per cent, of spongy platinum, strongly disposed to ignition. 

 Boiling muriatic acid dissolves it, but without development of nitric 

 or hydrocyanic acid, and forms an almost colourless solution, which 

 a solution of potash turns yellow, and which, on evaporation to dry- 

 ness, gives a residue, appearing partly red, partly yellow, and partly 

 blue,' and this by a strong heat is decomposed into hydrocyanic acid, 

 chloride of mercury, and cyanuret of platinum. 



The solution of the alkalies andalkaline earthsdecompose thecoloured 

 and the bleached precipitates, and separate, from the first, protoxide 

 and peroxide of mercury, from the latter, only peroxide ; at the same 

 time they leave their radical in combination with the cyanogen of the 

 cvanurel of mercurv, and in this combination form, with the cyanuret 

 of platinum, easily crystallizable double cyanurets of platinum. 

 When the white precipitate is gradually heated to redness in a glass 

 retort, it is decomposed into cyanogen gas, fluid mercury, and cya- 

 nuret of platinum. The quantity of the latter is about 48 per cent. 

 (4-8 grains from 10 grains on whichi experiniented)^ we may there- 

 fore consider the white precipitate as, a combination of 



48 Cyanuret of Platinum 1 _ pt Cy + Hy Cy, or Pt Hy Cy2. 

 52 Cyanuret of Mercury J j . j ^ ^ 



and we may consider the blue (and red) precipitate as a combination 

 of this double cyanuret with protonitrate of mercury. 1 have not yet 

 examined inwhot relation these salts stand to one another, and whe- 

 ther the blue colour belongs to the whole combination or merely to 

 one of its products (perhaps the oxide of platinum). 



The cyanuret of platinum which remains after the pyro-chcmical 

 decomposition of the colourless cyanuretof platinum and mercury, is a 

 fine olive-yellow pulverulent substance, insoluble in water, acids, or 

 alkalies, combustible, and when burnt in the air leaving 78 to 79 per 

 cent, of pure platinum, and when heated with oxide of copper in the 

 pyro-pneumatic ajjparatus giving carbonic acid and nitrogen gases 

 nearly in the proportion of '2 to 1 ; it therefore consists of one atom 

 of platinum and one of cvanogcn = Pt Cy. 

 ^ 2 () 2 



