992 CYANOGEN COMPOUNDS. 



mass, of which the faces reflect a copper lustre ; its solution is 

 strongly acid. 



COMPOUNDS OF CYANOGEN WITH OXYGEN. 



Cyanogen forms the three following isomeric acid compounds 

 with oxygen : 



Cyanic acid . . . HO,Cy O , 

 Fulminic acid . . 2HO,Cy 2 O 2 , 

 Cyanuric acid . . 3HO,Cy 3 O 3 . 



Cyanic acid, HO + CyO. This acid is formed when cyanogen 

 gas is dissolved in a solution of caustic potash, or passed over 

 carbonate of potash heated to redness ; also when ferrocyanide 

 of potassium in a fine powder is ignited in a shallow iron vessel, 

 with stirring and exposure to air at a low red heat. It does not 

 exist except in combination. The hydrated acid was prepared 

 by Woehler by distilling dry cyanuric acid, and collecting the 

 product in a receiver surrounded by ice. 



It is a transparent very volatile liquid, of a pungent odour, 

 highly corrosive, miscible with water. Soon after its preparation 

 this liquid spontaneously undergoes a very extraordinary 

 change ; it is converted with the evolution of heat into a white 

 solid matter, cyamelide, having the same composition in 100 

 parts, but insoluble in water and dilute acids, dissolved by 

 caustic alkali, with the formation of ammonia, a cyanate and 

 cyanurate of the alkali. The probable formula of cyamelide is 

 NH + C 2 O 2 (Liebig). Cyanic acid in solution reddens litmus at 

 first, but is soon transformed into bicarbonate of ammonia, by 

 uniting with the elements of 2 atoms of water : 



HO + C 2 NO and 2HO=NH 3 ,C 2 O 4 . 



Cyanates. The alkaline cyanates are soluble, all the others 

 are insoluble. They are recognised by the decomposition of 

 their acid, which occurs soon after it is liberated by another 

 acid. Ammonia forms two compounds with cyanic acid ; one 

 which contains more ammonia than belongs to a neutral salt is 

 produced when the acid vapour and dry ammoniacal gas are 



