Chemical Notices :^-Linnemann on Sulphocyanic Acid. 473 



Sulphocyanic acid, u > §, can be regarded as sulphuretted 



hydrogen in which an equivalent of hydrogen is replaced by 

 cyanogen. Linnemann has prepared the corresponding anhy- 

 dride of sulphocyanic acid by the action of iodide of cyanogen 

 on the sulphocyanide of silver. 



AgCyS + ICy = Agl + Cy 2 S 

 Sulphocyanide Iodide of Iodide of Anhydrous sulpho- 

 of silver. cyanogen. silver. cyanic acid. 



The reaction is exceedingly regular ; it takes place at a moderate 

 temperature, and is best effected when an etherial solution of 

 iodide of cyanogen is triturated at a gentle heat with the corre- 

 sponding quantity of the silver-salt. The product is treated 

 with bisulphide of carbon, by which the sulphide of cyanogen is 

 dissolved out, and, on cooling, is obtained in transparent rhombic 

 plates, or long thin lamime. It sublimes at 30° or 40°, and is 

 thereby obtained in small, highly refringent thin laminae. It is 

 heavier than bisulphide of carbon; it is dissolved by ether, alcohol, 

 and water, and readily crystallizes from the hot supersaturated 

 solution. It is decomposed by potash into cyanate and sulpho- 

 cyanide of potassium ; and with nascent hydrogen, sulphuretted 

 hydrogen, and sulphide of potassium it yields the same products, 

 namely hydrocyanic acid and sulphocyanic acid. It unites with 

 two molecules of ammonia to form a sulphide of cyanammonium 

 — a reaction quite analogous to that of sulphuretted hydrogen on 

 ammonia, which yields sulphide of ammonium. Thus, 



c y"W2Nip- NH3C Hs 



According to Lassaigne*, volatile chloride of cyanogen can be 

 obtained by the action of chlorine on an aqueous solution of 

 cyanide of potassium. A current of the gas is passed into a 

 solution of one part of cyanide of potassium contained in a roomy 

 flask which is kept cold with ice ; in the cork of this flask is 

 fixed a tube leading to a U-tube placed in a mixture of ice and 

 salt : the greater part of the chloride of cyanogen condenses in 

 this tube to colourless crystals. 



Bromide of cyanogen may be formed in an analogous manner 

 by adding bromine, which has been cooled to 0°, to a solution 

 of cyanide of potassium in water contained in a retort, which is 

 kept cold by means of ice. After a sufficient quantity of bro- 

 mine has been added, the retort is stoppered and gently warmed, 



* Liebig's Annalen (Supplement), December 1861. 



