Mr. Brett on Bromo-cyanide of Potassium and Mercury. 841 



One part of the salt requires about 13*34 parts of water, at 

 the temperature of 65° Fahr., for solution. It is however so- 

 luble in less than its own weight of boiling water. 



Diluted sulphuric acid does not decompose this salt even 

 when heat is applied, it however undergoes solution. 



Concentrated sulphuric acid, sp. gr. 1*845, does not decom- 

 pose it even upon the application of heat, it suffers solution 

 in the hot fluid, and is not thrown down again by the addition 

 of water. 



Neither diluted nor concentrated nitric acid appears to de- 

 compose it, although it undergoes solution. Hot nitric acid, 

 sp. gr. 1*48, dissolves it without apparent decomposition, water 

 does not throw it down from such solution. 



Hydro-chloric acid, sp. gr. 1*16, dissolves it even in the 

 cold, the hot fluid does not appear to decompose it. 



Sulphuretted hydrogen readily decomposes it with the evo- 

 lution of hydro-cyanic acid, it is also decomposed by the 

 hydro-sulphurets. The caustic alkalies, potass and ammonia, 

 do not decompose it. By the agency of heat it fuses and 

 blackens, suffering decomposition. 



In order to determine its atomic constitution, 15 grs. of the 

 salt, previously well dried over a sand-bath, were dissolved in 

 water, to this solution an excess of a concentrated acid solu- 

 tion of proto-chloride of tin was added, and the whole boiled 

 for a few minutes, during which time much hydro-cyanic acid 

 was evolved ; the vessel was then corked and kept at rest for 

 some hours, the clear supernatant fluid was then tested with 

 some more of the solution of the salt of tin ; no precipitate being 

 produced, the whole was carefully removed; the finely divided 

 metallic mercury at the bottom of the vessel was then boiled 

 for a short time only with pure hydro-chloric acid, after some 

 time the clear supernatant fluid was again removed, and after 

 boiling once more with diluted hydro-chloric acid, and re- 

 moving the greater part of the clear supernatant fluid, the 

 remainder, together with the metallic mercury, was transferred 

 to a small glass capsule, and allowed to dry at the prevailing 

 atmospheric temperature ; the mercury which had run into 

 globules was then weighed. 



Fifteen grains of the salt were again taken, dissolved in 

 water, and the solution treated with a slight excess of hydro- 

 sulphuret of ammonia, the whole was then boiled for a few 

 minutes, and when cold, filtered ; the filter was well washed 

 with distilled water, and the washing being added to the fil- 

 tered fluid, the whole was evaporated in a porcelain capsule 

 to a very small bulk, the fluid thus concentrated was transferred 

 to a platinum crucible, to which was added the washings of 



