Messrs. F. and E. Rodgers on certain Metallic Cyanurets. 09 



prepared by digesting the hydrated oxide with cyanuret of 

 potassium, owing to the oxide of manganese passing into a 

 higher state of oxidation, and to the rapid decomposition of 

 the double cyanuret itself. No experiment was made with 

 the anhydrous protoxide of manganese; but, as it has been 

 lately shown that ferrocyanuret of potassium is generated when 

 the anhydrous protoxide of iron is digested in a hot solution 

 of cyanuret of potassium, it is probable that the anhydrous 

 protoxide of manganese is soluble in the same solution. 



The hydrate of the oxide of chromium does not dissolve in 

 the solution of the cyanuret of potassium until hydrocyanic 

 acid is added ; the colour of the oxide is then changed to a 

 reddish brown, and a very small portion is dissolved. The so- 

 lution continues strongly alkaline. Acetic acid throws down 

 a brown precipitate from the solution. The solution of the 

 oxide is not assisted by digestion in the alkaline cyanuret. 

 It appears from these experiments that the sesquioxide of 

 chromium has very little tendency to form a double cyanuret 

 when digested with an alkaline cyanuret. 



It appears that the sesquicyanuret of uranium has very little 

 disposition to unite with cyanuret of potassium. It dissolves 

 very sparingly in the solution of the cyanuret : the solution, 

 which is alkaline, has a light yellow colour, and the undissolved 

 sesquicyanuret of uranium retains its beautiful yellow tint. On 

 the addition of hydrocyanic acid, both the cyanuret of uranium 

 and the solution assume a darker tint, but the odour of hy- 

 drocyanic acid does not disappear, which always happens on 

 the addition of hydrocyanic acid to the alkaline solutions of the 

 oxides of nickel, cobalt and copper in the solution of the cy- 

 anuret of potassium, unless the hydrocyanic acid is added in 

 excess. Hence, it would appear that the double cyanuret of 

 uranium and potassium does not exist. The sesquicyanuret 

 of uranium was employed in this experiment instead of the 

 peroxide, because it is easily obtained in a pure state by de- 

 composing the nitrate of uranium by a solution of cyanuret 

 of potassium. It is soluble in nitric acid. 



8. The double cyanurets may be formed by other processes : 

 for example, by the addition of a metallic sulphate to a solu- 

 tion of the cyanuret of barium ; thus ferrocyanuret of barium 

 is generated on the addition of protosulphate of iron to a solu- 

 tion of cyanuret of barium. At the first moment the precipitate 

 is -white, but a precipitate soon takes place which rapidly be- 

 comes blue. On examination the solution is found to precipi- 

 tate the protosaltsof iron light blue, and thepersalts dark blue. 



The red cyanuret of iron and potassium may be generated 

 02 



