HIPPUKIC ACID. 15 



Hippuric acid possesses a bitterish taste, and is much 

 more soluble than uric acid,, requiring for solution 400 parts 

 of water at the temperature of the air; it is much more 

 soluble, however, in boiling water. It is soluble in ether and 

 alcohol, and its solution reddens litmus paper. Pure hip- 

 puric acid crystallizes in long transparent prisms, as can be 

 seen in the accompanying engraving: 



Fig. 159. (THUDICUM.) Crystals of Hippuric Acid. 



Hippuric acid may be obtained by adding a considerable 

 excess of nitric or hydrochloric acid to the urine of a herbi- 

 vorous animal. The urine may with advantage be concen- 

 trated before the addition of the acid. The crystals, which 

 form in a few hours, have a disagreeable odour ; they may, 

 however, be purified by a rather complicated process. 



Hippuric acid has been detected in the blood of oxen and 

 calves; it is, therefore, like urea and uric acid, not formed by 

 the kidneys. 



It has been found, that when benzoic acid is taken into 

 the system, an almost equal amount of hippuric acid forces 



