712 URINE. 



filter by water (total 100 cc.) into a flask, treated with 15 cc. of con- 

 centrated sulphuric acid, and titrated at 60-63 C. with N/20 potassium- 

 permanganate solution. Each cubic centimeter of this solution cor- 

 responds to 3.75 milligrams uric acid. Because of the solubility of the 

 ammonium urate a correction of 3 milligrams must be added for every 

 100 cc. of the urine. 



In regard to the numerous other methods for estimating uric acid, 

 we must refer to special works on the subject, and especially to HUPPERT- 

 NEUBAUER. FOLIN with MACULLUM JR. and with DENIS 1 have sug- 

 gested a colorimetric method for estimating uric acid, making use of 

 phosphotungstic acid. 



Purine Bases ( ALLOXURIC BASES) . The purine bases found in human 

 urine are xanthine, (guanine), hypoxanthine, adenine, paraxanthine, 

 heteroxanthine, episarkine, epiguanine, l-methylxanthine. The occur- 

 rence of guanine and carnine (POUCHET) is, according to KRUGER and SALO- 

 MON, 2 not positively shown. The quantity of these bodies in the urine 

 is extremely small and varies in different individuals. FLATOW and REIT- 

 ZENSTEIN 3 found 15.6-45.1 milligrams in the urine voided during twenty- 

 four hours. The quantity of alloxuric bases in the urine is regularly 

 increased after feeding with nucleins or food rich in nucleins, and after an 

 abundant destruction of leucocytes. The quantity is especially increased 

 in leucaemia. We have a number of observations on the elimination of 

 these bodies in different diseases, but they are hardly trustworthy on 

 account of the inaccuracy of the methods used in the determinations. 

 It must also be remarked that the three purine bases, heteroxanthine, 

 paraxanthine, and l-methylxanthine, which form the chief mass of the 

 purine bases of the urine, are derived, according to numerous investiga- 

 tions 4 from the theobromine, caffeine, and theophylline which occur 

 in the food. With the purine bases we must also differentiate between 

 those of endogenous and those of exogenous origin, 5 and the same factors 

 apply as for the uric acid, viz., the endogenous purine formation represents 

 a value which is somewhat variable for different individuals and relatively 



1 Journ. of biol. Chem., 13 and 14. 



2 Zeitschr. f. physiol. Chem., 24; Pouchet, " Contributions a la connaissance des 

 matieres extractives de 1'urine." These, Paris, 1880. Cited from Huppert-Neubauer, 

 333 and 335. 



3 Deutsch. med. Wochenschr., 1897. 



4 Albaneee, Ber. d. d. chem. Gesellsch., 32; Arch. f. exp. Path. u. Pharm., 35; 

 Bondzynski and Gottlieb, ibid., 36, and Ber. d. deutsch. chem. Gesellsch., 28; E. 

 Fischer, ibid., 30, 2405; Kriiger and Salomon, Zeitschr. f. physiol. Chem., 26; Kriiger 

 and Schmidt, Ber. d. d. chem. Gesellsch., 32, and Arch. f. exp. Path. u. Pharm., 45; 

 Kotake, Zeitschr. f. physiol. Chem., 57. 



5 See Burian and Schur, footnote 2, page 702, and Kaufmann and Mohr, Deutsch. 

 Arch. f. klin. Med., 74. 



