URIC ACID. 199 



quantity of hippuric acid found in the urine, (as, for instance, after 

 the ingestion of from two drachms to half an ounce of benzoic 

 acid,) and that the same substance is separated even more abun- 

 dantly from the liver. Glycine must therefore be regarded in the 

 same light as urea, as a common product of decomposition of 

 nitrogenous substances. 



We cannot therefore find any very immediate source from 

 which either of the proximate constituents of this acid can be 

 derived, since neither physiological nor pathological relations 

 elucidate the process by which it is formed in the animal body. 



This much, however, is certain, that hippuric acid is to be 

 regarded merely as a product of excretion, and consequently that 

 it can have no special uses in the animal organism. 



It is to be regretted that benzoic acid is so rarely prescribed 

 by the physician ; and that, even in those cases, it is usually order- 

 ed on most irrational principles. It deserves to be thoroughly 

 tested in a pharmacological point of view; it certainly possesses 

 one great advantage over all the other officinal acids in its property 

 of rendering the urine strongly acid. Ure attaches great importance 

 to this circumstance, but it does not appear to have been turned to 

 much account in actual practice. 



URIC ACID. C 5 HN 2 O 2 .HO. 



Chemical Relations. 



Properties. Pure uric acid occurs either in a glistening white 

 powder, or in very minute scales, which under the microscope are 

 seen to consist of irregular plates, whose crystalline form (see our 

 remarks on the crystals, in the consideration of the "Tests/ 5 ) 

 cannot very well be made out : it is a substance devoid of odour 

 and taste ; it requires 1800 or 1900 parts of hot, and 14000 or 15000 

 parts of water at the ordinary temperature of 20, to dissolve it ; it 

 is insoluble in alcohol and ether, and does not redden litmus. It 

 dissolves in concentrated hydrochloric acid somewhat more readily 

 than in water ; it dissolves tolerably freely> and without decompo- 

 sition, in concentrated sulphuric acid, but is again precipitated on 

 the addition of water. It dissolves readily in the alkaline carbo- 

 nates, borates, phosphates, lactates, arid acetates, since it abstracts 

 some of the alkali from these salts, and is thus rendered more 

 soluble. Uric acid is expelled from all its salts by acetic as well as 



