178 PATHOLOGY OF PURIN METABOLISM 



In what form does the uric acid, a substance relatively 

 difficult of solution when free, exist when it is dissolved in the 

 blood t 



Alkali Compounds of Uric Acid. One would undoubtedly 

 first think of the uric acid as being in some alkali combina- 

 tion for its solution in the circulating blood. What are the 

 known types of alkali-compounds of uric acid ? First may be 

 mentioned combinations of the type of sodium monourate 

 (C 5 H 3 N 4 3 .Na) and of sodium biurate (C 5 H 2 N 4 O 3 .Na 2 ) ; but 

 it should also be noted that the readily soluble biurate of 

 sodium cannot exist in the presence of the haemic carbonic 

 acid. Besides these the existence of combinations of the 

 type C 5 H 3 N 4 3 Na.C 5 H 4 ]Sr 4 03 is assumed. These last have 

 been called " quadriurates " by Bence- Jones and Roberts; 

 but the name should for logical reasons be changed to 

 ' ' hemiurates. ' * The assumption that these (met with in the 

 latericious urinary sediment and in the excrement of birds 

 and snakes) correspond structurally to a fixed molecular 

 proportion (one atom of sodium to two molecules of uric 

 acid) is not confirmed by recent investigations. In all prob- 

 ability the quadriurates are in reality a mixture of primary 

 urate and free uric acid, which is usually fairly constant 

 under uniform external conditions, thus necessarily suggest- 

 ing the formation of mixed-crystals (solid solutions). 17 



Part Taken ~by Changes in Alkalescence. In the older 

 conceptions of the pathology of gout the hypothesis that 

 separation of the uric acid from the blood into the tissues 

 was due to a lowering of the alkalescence of the blood or of 

 the tissue-juices, was maintained strongly. In spite of 

 the fact that one of the greatest experts on gout, C. v. 

 Noorden, 18 long since characterized all theorizations upon 



" W. E. Ringer (Physiol. Instit., Utrecht.), Zeitschr. f. physiol. Chem., 67, 

 332, 1910; 75, 13, 1911; R. Kohler (His's Clinic, Berlin), ibid., 70, 360, 1911; 

 72, 169, 1911; O. Rosenheim, ibid., 71, 272, 1911. 



" C. v. Noorden, Handb. d. Pathol. d. Stoffwechsels., 2d ed., 2, 168, 169, 1907. 



