9-t Messrs. F. and E. Rodgers on certain Metallic Cyanurets. 



fusion ; cyanogen is not evolved, but metallic mercury is sub- 

 limed, oxygen and carbonic acid gases are disengaged with 

 effervescence, and at length the mixture becomes white. On 

 the addition of a fresh portion of the bicyanuret of mercury, 

 the same phenomena take place; but the mixture then enters 

 into complete fusion. 



The bicyanuret of mercury employed in this experiment 

 must be quite pure and well dried, otherwise the cyanuret of 

 potassium has a yellow colour. Atomic proportions may be 

 employed ; but as it is better to allow the alkaline carbonate 

 to be in slight excess, the best proportions are 120 grains of 

 the dry bicyanuret of mercury to 70 grains of anhydrous car- 

 bonate of potash. When the mass is cold, the cyanuret of 

 potassium may be separated from any undecomposed carbo- 

 nate of potash by digestion in boiling rectified spirit, and the 

 cyanuret may be obtained in crystals by concentrating the al- 

 coholic solution; but this is not often necessary, as cyanuret 

 of potassium is not very soluble in alcohol. 



The process may be performed in a green glass tube, or in 

 a clean Hessian crucible. It cannot be performed at a full 

 red heat; for, under certain circumstances, cyanuret of potas- 

 sium appears to be volatile in an open crucible at that tem- 

 perature ; thus, on projecting dry bicyanuret of mercury into 

 fused carbonate of potash, cyanogen gas is copiously evolved 

 and inflames, whilst the crucible becomes filled with a kind of 

 mist ; but immediately after this appearance cyanogen ceases 

 to be evolved. Sometimes the whole of the matter is dissi- 

 pated ; but usually after the crucible is cold a yellowish mass is 

 found at the bottom, much less in weight than the cyanuret 

 obtained at a low red heat, and the aqueous solution of this sub- 

 stance does not evolve the odour of hydrocyanic acid, but ef- 

 fervesces strongly with acids. Finally, the process cannot be 

 performed in platinum vessels, for platinum is attacked. It is 

 evident that in this process both the bicyanuret of mercury 

 and the carbonate of potash are decomposed, the metallic 

 mercury being sublimed, and the carbonic acid and oxygen 

 gases expelled, whilst cyanogen unites with potassium. 



Cyanuret of sodium may be obtained by a similar process, 

 substituting about 54 grains of anhydrous carbonate of soda 

 for 70 grains of carbonate of potash. The process requires 

 to be performed at a temperature rather higher than a low 

 red heat. The tube employed must be made of green glass, 

 or the process may be performed in the bottom of a Florence 

 flask ; for a common glass tube is rapidly attacked, blackened, 

 softened, and finally destroyed. 



The changes which take place during the formation of this. 



