CYANURIC ACID, CHLORIDES OF CYANOGEN. 997 



colourless by repeated crystallization, or when this fails by dis- 

 solving in concentrated sulphuric acid and precipitating by 

 water. The white precipitate by water gives colourless crystals 

 of cyanuric acid from a solution in boiling water. In this pro- 

 cess, melam on dissolving in sulphuric acid is transformed into 

 ammonia and ammelide, and the last in contact with the acid 

 diluted with water is resolved into ammonia and cyanuric acid, 

 as expressed in the following equations : 



Melam. Water. Arameline. Ammonia. 



C 12 N U H 9 and 6HO=C 12 N 9 H 9 O 6 and 2NH 3 . 



Ammeline. Cyanuric acid. Ammonia. 



C 12 N 9 H 9 6 =C 12 N 6 6 and 5NH 3 



Cyanuric acid has a feeble acid taste, is slightly soluble in 

 cold water and dissolves in 24 parts of boiling water. The 

 crystals from water are oblique prisms of a rhombic base ; they 

 contain 4HO, which they lose in air at the ordinary temperature. 

 Cyanuric acid is obtained anhydrous and crystallized, from a 

 concentrated and boiling solution in nitric or hydrochloric acid. 

 One atom of cyanuric acid is decomposed by dry distillation and 

 resolved into 3 atoms of hydrated cyanic acid, of which it con- 

 tains the elements. It dissolves with the aid of heat in the 

 concentrated mineral acids, without decomposition, but is 

 decomposed by continued boiling with the formation of carbonic 

 acid and ammonia. 



Cyanurates. In these salts the three atoms of water of the 

 hydrate of cyanuric acid are replaced in whole or in part by 

 metallic oxides. They are all completely decomposed, and their 

 acid liberated by nitric and hydrochloric acids. 



.: 



Gaseous chloride of cyanogen, CyCl, is most conveniently 

 prepared by passing chlorine in excess into an aqueous solution 

 of hydrocyanic acid, and expelling the chloride of cyanogen by 

 a gentle heat. It is a gas at the ordinary temperature having 

 an insupportable, penetrating odour, and provoking tears. At 

 Fahr., it crystallizes in long needles like spiculse of ice. It 

 undergoes a metamorphosis if confined liquid in a tube, and 

 deposits the solid isomeric chloride of cyanogen (Persoz). It 

 combines with ammonia, as CyCl + 2NH 3 . 



