CYANOGEN COMPOUNDS. 213 



of potassium cyanate and ethyl sulphate. Colorless 

 liquid, boiling at 60, of a strong odor. With water it 

 decomposes immediately, forming diethylurea (which 

 see), an evolution of carbonic anhydride taking place 

 at the same time ; heated with potassa, it yields ethyla- 

 mine (p. 56) and potassium carbonate. It combines 

 directly with one molecule of dry hydrochloric or 

 -bromic acid, forming liquid compounds, which are de- 

 composed by water, yielding ethylamine hydrobromate 

 (or hydrochlorate) and carbonic acid. 



Sulphocyanic Add (Rhodanic Add). 

 CKSH. 



The alkaline salts of this acid are produced by the 

 direct combination of the cyanides with sulphur. For 

 the purpose of preparing the free acid, the potassium 

 salt is distilled with dilute sulphuric acid. It is ob- 

 tained in an anhydrous state by decomposing the mer- 

 cury salt with hydrochloric acid. Colorless oil, mixes 

 in all proportions with water, congeals at 12.5. 

 Monobasic acid. The solutions of the free acid, as 

 well as of its salts, are turned intensely red on the addi- 

 tion of a solution containing iron oxide. Decomposes 

 very easily, particularly in an anhydrous condition, 

 into potassium cyanide and yellow crystalline persul- 

 phocyanic add (hydroxanthanic acid) (CE") 2 H 2 S 3 ; but 

 very slightly soluble in water. 



Potassium sulpho cyanate, C1ST.SK, can be most 

 readily prepared by fusing together 46 parts dehydrated 

 potassium ferrocyanide, 17 parts potassium carbonate, 

 and 32 parts sulphur. The melted mass is poured off, 

 allowed to cool, and then extracted with alcohol. 

 Large, colorless prisms, very easily soluble in water. 

 When air is excluded it fuses without decomposition. 



Ammonium sulphocyanate, C!N".S(OT3 4 ), is ob- 

 tained by digesting mercury cyanide with ammonium 

 sulphide ; or ammonium cyanide with sulphur. Can 

 be prepared most easily by treating carbon bisulphide 



