64 



Edmund Davy proceeds to detail the processes by which he suc- 

 ceeded in procuring it. 



A solution of leaf platinum in nitro-muriatic acid was evaporated 

 to dryness, re-dissolved in water, and precipitated by sulphuretted 

 hydrogen. This hydro-sulphuret was converted into a sulphate by 

 the action of nitrous acid. Ammonia, in slight excess, was added 

 to the solution of this sulphate, and the precipitate so obtained boiled 

 in a solution of pure potash. It was then collected on a filter, washed, 

 and dried at 212. This powder is of a brown colour, explodes with 

 a loud report when heated to about 400, and lacerates the substance 

 in contact with it, in the same way as fulminating gold. At a tem- 

 perature of 300 it is decomposed without explosion when in contact 

 with mercury. It explodes by friction, but not by percussion. It 

 is tasteless ; insoluble in water, soluble in sulphuric, nitric, and 

 muriatic acids. When heated in chlorine, muriate of ammonia and 

 muriate of platinum are produced. When heated in ammonia and 

 in muriatic acid gas, it is decomposed ; and in the latter, with nearly 

 the same phenomena as in chlorine. Heated with sulphur, it affords 

 sulphuret of platinum. 



From the method pursued in obtaining this compound, the author 

 inferred its resemblance to fulminating gold ; and on heating it in 

 close vessels, obtained water, nitrogen, and platinum, as the results 

 of its decomposition. Heated with common quick-lime, it afforded 

 liquid ammonia and a little nitrogen. 



Mr. Edmund Davy next proceeds to a detail of experiments made 

 in order to ascertain the relative proportions of the component parts 

 of this new fulminating platinum. 



In these experiments, 10 grains of the powder furnished 7 '3 grains 

 of metallic platinum. 



In a fourth experiment, nitrous acid was boiled to dryness upon 

 10 grains of the powder. The dry mass heated red-hot, furnished 

 8'25 grains of a gray shining substance, which is a hitherto unde- 

 scribed oxide of platinum, consisting of 88'3 platinum +11*7 oxy- 

 gen. From the quantity of nitrogen yielded during the decompo- 

 sition of the fulminating platinum, and from other experiments, Mr. 

 Davy estimates the quantity of ammonia that it contains, at 9 per 

 cent, and gives as its component parts, 



78'75 platinum. 1 - - -j c i . 

 ., __ * } 82'o oxide of platinum. 



3*75 oxygen. J 



9'00 ammonia. 

 8-50 water. 



100-00 



This paper concludes with some general and theoretical observa- 

 tions respecting the formation and decomposition of the new fulmi- 

 nating compound. When the triple sulphate of platinum and ammo- 

 nia is boiled in a solution of potash, the sulphuric acid unites to the 

 potash, a portion of the ammonia is evolved, and the remainder, 



