HIPPUKIC ACID. 337 



Large, colorless, rhombic prisms, of a weak taste ; 

 soluble in 600 parts of cold water, much more readily 

 in boiling water, and in alcohol. Fusible without 

 decomposition. Heated above its fusing point, it is 

 decomposed, and yields hydrocyanic and benzoic acids 

 and benzonitrile. 



By boiling with acids or alkalies, it is resolved into 

 benzoic acid and glycocol, the elements of water being 

 assimilated. The same decomposition is effected by 

 ferments. By heating with manganese superoxide 

 and dilute sulphuric acid, it yields benzoic acid, car- 

 bonic anhydride, and ammonia. Nitrous acid converts 



it into benzoylglycolic acid, C 9 H 8 O = CH 2 j QQQH? 



which crystallizes in thin, colorless prisms, difficultly 

 soluble in cold water, easily in hot water, and alcohol. 

 Monobasic acid. Most of the hippurates, even the 

 silver and lead salts, are soluble in water, and crystal- 

 lizable. 



Ethyl hippurate, C 8 H 8 N0 3 .C 2 H 5 , is produced by 

 saturating a boiling solution of hippuric acid in alcohol 

 with hydrochloric acid gas. On the addition of water, 

 the ether subsequently separates as an oil, which soon 

 becomes crystalline. It crystallizes in long, colorless 

 prisms of a silky lustre, but slightly soluble in water, 

 easily in alcohol and ether ; fuses at 44 ; not volatile 

 without decomposition. 



Chlorhippuric acid, C 9 H 8 C1N0 3 , and Dichlprhip- 

 puric acid, C 9 H 7 Cl 2 iTO 3 , are produced, when to hippuric 

 acid, in a vessel containing concentrated hydrochloric 

 acid, potassium chlorate is added and the whole gently 

 heated. The former is oleaginous, viscid, uncrystal- 

 line ; the latter crystallizes gradually, when left in con- 

 tact with the air or under water. Boiled with acids or 

 alkalies, chlorhippuric acid yields glycocol and meta- 

 chlorbenzoic acid ; dichlorhippuric acid yields glyco- 

 col and dichlorbenzoic acid. Chlorhippuric acid occurs 

 in the urine after metachlorbenzoic acid is taken into 

 the system. 

 29 



