98 Messrs. F. and E. Rodgers on certain Metallic Cyanurets, 



cyanuret of potassium, adding hydrocyanic acid as before. The 

 excess of oxide of nickel assumes a dusky yellow colour. The 

 solution is yellow, and is not affected by any of the reagents 

 which detect the presence of oxide of nickel. The solution 

 throws down from the sulphate of copper a pale yellow gela- 

 tinous precipitate, soluble in ammonia, forming a colourless 

 solution; but if the salt of copper is in excess, the solution 

 is blue : the precipitate, somewhat changed, is thrown down 

 from the ammoniacal solution by the nitric, muriatic and sul- 

 phuric acids. A white flocculent precipitate is produced in 

 the solution of the nitrate of silver, which is soluble in ammo- 

 nia, insoluble in nitric acid, and unchanged by the solar 

 rays. From the protosulphale of iron a white precipitate is 

 thrown down, which changes to a very light blue after stand- 

 in"- some time. The solution precipitates the persalts of iron 

 reddish yellow, and the precipitate, which is rather bulky, be- 

 comes redder after standing some time, but never becomes 

 blue. The solution throws down a white precipitate, with 

 a slight tinge of blue, from the solution of pure sulphate of 

 nickel, and a flocculent white precipitate, soluble in nitric acid, 

 from the acetate of lead. 



When a current of chlorine is transmitted through the so- 

 lution, a white precipitate takes place. The filtered solution 

 is still neutral, but no longer precipitates the salts of lead. 



A double cyanuret of cobalt and potassium may be formed 

 by adding pure hydrated oxide of cobalt to a solution of cy- 

 anuret of potassium : the oxide is immediately dissolved, and 

 the solution becomes yellow, but continues alkaline; the colour 

 of the solution soon changes to a brownish hue. On the ad- 

 dition of hydrocyanic acid an additional quantity of the oxide 

 is taken up, the solution returns to its yellow colour, and is 

 then quite neutral. No change is produced in the solution 

 by the reagents employed to detect oxide of cobalt. The so- 

 lution precipitates the sulphate of copper -pale blue, the pure 

 sulphate of cobalt J9z'»/f, pure sulphate of nickel very light green, 

 sulphate of zinc white, nitrate of silver Jlocculent white, and 

 pi-otonitrate of mercury, sulphate of manganese and protosul- 

 phate of iron also white ; but it produces no change in the so- 

 lution of the persulphate of iron. 



L. Gmelin prepared a double cyanuret of cobalt and potas- 

 sium, analogous to the red cyanuret of iron and potassium, by 

 dissolving the carbonate or the cyanuret of cobalt in solution of 

 potash, and neutralizing the solution with hydrocyanic acid, 

 perhaps the double cyanuret prepared by dissolving the oxide 

 :_ also analogous to the same salt, for the solution suffers no 

 change when a current of chlorine is passed through it. 

 A double cyanuret of manganese and potassium cannot be 



