808 URINE. 



chloride has disappeared. After standing sufficiently long the ester is collected, 

 finely divided, and saponified with an alcoholic solution of sodium ethylate in the 

 cold according to BAISCH'S method, 1 and the various carbohydrates separated 

 according to his suggestion. 



If small quantities of sugar are to be isolated from the urine, precipitate the 

 urine first with sugar of lead, filter, precipitate the filtrate with ammoniacal 

 basic lead acetate, wash this precipitate with water, decompose it with H 2 S when 

 suspended in water and use the filtrate for the special tests. SCHONDORFF 2 

 has suggested a method for the detection and estimation of very small amounts 

 of sugar based upon the work of PATEIN and DUFAU. This method depends 

 upon precipitating the nitrogenous substances with mercuric nitrate. 



To the physician, who naturally wants simple and quick methods, 

 the bismuth test is especially to be recommended. If this test gives neg- 

 ative results, the urine is to be considered as free from sugar in a clinical 

 sense. If it gives positive results, the presence of sugar must be con- 

 trolled by other tests, especially by the fermentation test. 



Other tests for sugar, as, for example, the reaction with orthonitrophenyl- 

 propiolic acid, picric acid, diazobenzene-sulphonic acid, are superfluous. The 

 reaction with a-naphthol, which is a reaction for carbohydrates in general, for 

 glucuronic acid and mucin, may, because of its extreme delicacy, give rise to 

 mistakes, and is therefore not to be recommenced to physicians. Normal urines 

 give this test, and if the strongly diluted urine gives the reaction the presence 

 of great quantities of carbohydrates may -be suspected. In these cases more 

 positive results are obtained by using other tests. This test requires great clean- 

 liness, and it has the inconvenience that sufficiently pure sulphuric acid is not 

 always readily procurable. Several investigators, such as v. UDRANSKY, LUTHER, 

 Roos and TREUPEL, 3 have investigated this test in regard to its applicability 

 as an approximate test for carbohydrates in the urine. 



Quantitative Determination of Sugar in the Urine. The quantity of 

 sugar can be determined by titration, by fermentation of the sugar, by 

 polarization, and also in other ways. 



The titration methods are based upon the property of the sugar to 

 reduce metallic oxides in alkaline solutions. As the titration liquids 

 (cupric oxide solution in the FEHLING-SOXHLET, PAVY, BANG, BERTRAND 

 methods and mercuric oxide in KNAPP'S method) are also reduced by 

 other urinary constituents, these reduction methods always give too high 

 results. When large quantities of sugar are present, as in typical 

 diabetic urine, which generally contains a lower percentage of normal 

 reducing constituents, this is indeed of little account; but when small 

 quantities of sugar are present in an otherwise normal urine, the mistake 

 may, on the contrary, be important, as the reducing power of normal 

 urine may correspond to 5 p. m. glucose (see page 749). In such cases 

 the titr.ation procedure must be employed in connection with the fer- 

 mentation method, which will be described later. 



1 Zeitschr. f. physiol. Chem., 19. 



8 Pfliiger's Arch., 121, which cites the work of Patein and Dufau. 



' See Roos and Treupel, Zeitschr. f. physiol. Chem., 15 and 16. 



