96 Messrs. F. and E. Rodgers on certain Metallic Cyanurets. 



when the mass is heated ; and the cyanuret of sodium may be 

 separated from any undecomposed carbonate of soda by means 

 of boiling rectified spirit. 



The quantity of the cyanurets obtained by this mode is ex- 

 tremely variable : the difference appears to depend upon the 

 more or less rapid application of heat. 



6. Cyanuret of barium may be obtained in a pure form by 

 the process described by Berzelius and Thenard ; viz. by 

 heating the dry ferrocyanuret of barium to redness in covered 

 porcelain crucibles. The cyanuret of barium is very soluble 

 in water, but it also dissolves in boiling rectified spirit. 



7. The cyanurets of the common metals, and the double 

 cyanurets formed by the union of these compounds with the 

 cyanurets of the bases of the alkalies and alkaline earths, are 

 described in the system of Berzelius ; but the following expe- 

 riments appear to show that the latter compounds may be 

 formed by processes different from those mentioned by that di- 

 stinguished chemist. It appears that Gay-Lussac procured 

 the double cyanuret of iron and potassium by digesting the 

 black oxide of iron in a solution of cyanuret of potassium. 

 The cyanuret of potassium dissolved a portion of the oxide, 

 but the solution continued alkaline: on the addition of hydro- 

 cyanic acid a fresh portion of the oxide was dissolved and the 

 solution became neutral. Gay-Lussac also obtained the double 

 cyanuret of silver and potassium by digesting cyanuret of 

 silver in a solution of cyanuret of potassium ; part of the cy- 

 anuret of silver was dissolved, and the solution became neutral 

 on the addition of hydrocyanic acid. Berzelius, who describes 

 these compounds as the discovery of Ittner, does not men- 

 tion the latter important circumstance. 



The following experiments appear to show that cyanuret of 

 potassium is capable of dissolving many other oxides. 



Hydrated protoxide of copper, prepared by precipitating the 

 sulphate by pure potash, was digested, whilst moist, in a solu- 

 tion of cyanuret of potassium, which dissolved a certain por- 

 tion, but continued alkaline. On the addition of hydrocyanic 

 acid, the oxide assumed a yellow colour, an additional quan- 

 tity was dissolved, and the solution, which had a red colour, 

 became quite neutral. The presence of copper cannot be de- 

 tected by any of the usual reagents, until the solution is boiled 

 with a little sulphuric acid. Berzelius states that the solution 

 prepared by Ittner was of a yellow colour, and gave little 

 yellow prisms on cooling, whilst Gmelin prepared a double 

 cyanuret of copper and potassium in colourless rhombohedral 

 prisms. 



The solution prepared by the process just described is 



