998 CYANOGEN COMPOUNDS. 



Solid chloride of cyanogen, Cy 3 Cl 3 , corresponds in constitution 

 with cyanuric acid ; it is formed when a mixture of dry chlorine 

 and hydrocyanic acid is exposed to the direct rays of the sun. 

 It is white and sublimes in diaphanous needles. When 

 digested in hot water, it is resolved into hydrochloric and cya- 

 nuric acids. It combines also with ammonia, as Cy 3 Cl 3 + 

 3NH 3 . 



Bromide of cyanogen, CyBr, crystallizes in cubes, but is 

 gaseous at 59. 



Iodide of cyanogen, Cyl, forms snowy flocks, white and 

 crystalline, which volatilise at 113. 



SULPHOCYANOGEN. 



Its formula as it exists in combination is CyS 2 ; or it is the 

 bisulphuret of cyanogen. 



When chlorine is transmitted into a strong solution of sulpho- 

 cyanide of potassium, a solid matter of a fine yellow colour is 

 precipitated which was considered as sulphocyanogen, but has 

 been shown, by Mr. Parnell, to be different, and named meta- 

 sulphocyanogen. Sulphocyanogen, as it exists in the sulpho- 

 cyanide has riot yet been isolated. 



Hydrosulphocyanic acid, H -f CyS 2 is obtained by decomposing 

 the basic sulphocyanide of lead by dilute sulphuric acid, and com- 

 pleting the decomposition by sulphuretted hydrogen. It is a co- 

 lourless liquid of a sour taste, which spontaneously resolves itself 

 in air into several products. It has not been obtained anhydrous. 

 It colours red the solution of a persalt of iron ; it is not 

 poisonous. 



Sulphocyanides. The preparation of sulphocyanide of potas- 

 sium has already been described (page 452). The neutral 

 sulphocyanide of lead is deposited in yellow opaque and bril- 

 liant crystals, on mixing concentrated solutions of acetate of 

 lead and sulphocyanide of potassium. The basic sulphocyanide, 

 Pb,CyS 2 -f PbO, on throwing the neutral salt into boiling water, 

 or on adding the tribasic acetate of lead to sulphocyanide of 

 potassium. It is a yellowish white crystalline powder, insoluble 

 in water. 



