286 On the Volumetric Determination of Uric Acid. [June 7, 

 I c.c. KH 4 CNS = 0-00168 Uric Acid. 





Salkowski (200 c.c. urine). 



Haycraft (25 c.c. urine). 



Expt. 



Quantity of uric 

 acid obtained. 



Mean per- 

 centage. 



No. of c.c. of 

 NH^NS re- 

 quired. 



Mean 

 equivalent 

 quantity of 

 uric acid. 



Per- 

 centage. 



I. 



0*168 gr. 



0-084 



(a.) 16 -2 c.c. 

 (p.) lb d „ 



\ 0-027 

 J 



0-108 



II. 



0*07 gr. 



0-035 



(a.) 11 -8 c.c. 

 (b.) 11-4 „ 

 (c.) 11-0 „ 



| 0-019 



076 





(a.) 0-098 gr. 

 (b.) 0-1045 „ 



| 0-051 



(a.) 12 -3 c.c. 

 (b.) 12 1 „ 



| 0-0205 



0-082 



xv.{ 



(a.) -068 gr. 

 (ft.) 0-073 „ 



| 0-035 



(a.) 10-7 c.c. 

 (b.) Il l „ 



| 0-018 



0-072 





(a.) 0-154gr. 

 (b.) 0-160 „ 

 (c.) 0-165 „ 



| 0-08 



(a.) 16 -3 c.c. 

 (J.) 16-4 „ 



} 0-027 



0-108 



The results obtained by Haycraft's method were always con- 

 siderably higher than those obtained by Salkowski's. The reason of 

 this is that Dr. Haycraft has assumed that the silver precipitate from 

 urine consists of an urate containing only 1 atom of silver in the 

 molecule, whereas the proportion of silver in this precipitate is 

 always larger, and varies in amount in different urines. If we assume 

 that the precipitate contains 2 atoms of silver in a molecule of urate 

 and divide the results obtained by Haycraft's method by two, we see 

 that in two cases they are about equal to, in the rest less than those 

 obtained by Salkowski's method. The proportion of the results 

 obtained by one method to those obtained by the other varies. This 

 agrees with the results of Salkowski's researches, from which one 

 would expect that the results obtained by Haycraft's method would 

 not bear a constant relation to the results obtained by Salkowski's, 

 and that the halves of the results by the former method would be 

 lower than, in most cases, those obtained by the latter. 



