148 Dr. A. B. Garrod. Certain Points in [June 19, 



The comparison with Gordon is more uncertain, inasmuch as his 

 observations were made on light of the refrangibility of the thallium 

 line. The corrected* result for this light is in circular measure 

 l'5238xlO~ B , or '05238 minute. To pass to sodium we may use a 

 formula given by Becquerelf and Verdet according to which the 

 rotation for different wave-lengths (X) is proportional to/**(/t 2 1)X~ 2 , 

 M being the refractive index. At this rate the "05238 minute for 

 thallium would be '04163 minute for sodium. The temperature was 

 not directly observed by Gordon, but was estimated to be about 13 C. 

 Assuming this to be correct, the value for 18 would be '0413 

 minute, or about 2 per cent, less than according to my determina- 

 tions. 



XII. " Certain Points in connexion with the Physiology of Uric 

 Acid." (Supplemental.) By ALFRED BARING GARROP, M.D., 

 F.R.S. Received June 19, 1884. 



(Abstract.) 



One of the objects of the present paper is the correction of an 

 error of interpretation in the author's communication of February 

 15th, 1883. Another object is to make known certain facts which he 

 has ascertained in seeking to correct the same. 



The author hopes, 1st, to give a true explanation of the phenomena 

 previously misinterpreted ; 2ndly, to make known some facts hitherto 

 unknown, whence arose the error in question ; and 3rdly, to show 

 the existence of certain peculiarities in the urine of herbivorous 

 mammals, with regard to uric acid, which peculiarities the author 

 anticipated, so that he was led to undertake numerous experiments 

 and observations with the object of verifying or disproving such 

 anticipations. 



The subject discussed in Part I is the influence of alkaline carbo- 

 nates upon uric acid. Many experiments are detailed, and, as a 

 result it is found that weak solutions of the alkaline carbonates, 

 when exposed to the air, possess the power of decomposing uric acid 

 in solution, and that oxalic acid and urea are among the products of 

 the decomposition. By the recognition of this fact certain pliysio- 

 logical phenomena in relation to the urine can be explained. 



Part II is devoted to the demonstration of the action of glycocine 

 (glycocoll) and a few other substances in protecting uric acid from 



* Mr. Gordon's result was originally given at double it proper value, 

 t " Ann. d. Chim.," t. xii, 1877, p. 78. 



