IIIPPURIC 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 akohol. 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 eftected by 

 ferments. By heating with manganese superoxide 

 and dilute sulphuric acid, it yields benzoic acid, car 

 bonic anhydride, and ammonia. Nitrous acid converts 



( C 7 IPO 

 it into benzoylglycolic acid, C 9 H 8 4 = CH 2 j QQ.OH, 



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 Dichlorhip- 



puric acid, C 9 H 7 C1 2 X0 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- 

 chlorbcnzoic acid ; dichlorhippuric acid yields glyco 

 col and dichlorbenzoic acid. Chlorhippuric acid occurs 

 in the urine after metachlorbenzoic acid is taken into 

 the system. 

 29 



