306 PHYSIOLOGICAL CHEMISTRY 



solution is colorless. A white precipitate forms during the 

 titration. If the liquid in the dish becomes too concentrated, 

 add water. 



Calculation. Exactly 50 mg. of glucose will reduce the 25 c.c. 

 of the copper reagent. This amount of glucose must have been 

 present in the volume of urine used, provided no other reducing 

 substances were present. If the urine was diluted 10 times, 

 then the per cent of glucose in the original urine was 

 0.050 X 1000 where x is the volume of urine used from the 



x 

 burette. 



b. FERMENTATION TESTS. 



Perform a fermentation test on carbohydrate urine. 



This test is a very satisfactory one, as the other reducing sub- 

 stances in the urine do not ferment. It furnishes also a means 

 of differentiation between dextrose and lactose as certain 

 varieties of yeast will ferment dextrose but not lactose. 



c. PHENYLHYDRAZINE TEST. 



This test is carried out as described under carbohydrates, and 

 may be used to distinguish various members of the group. 



d. OPTICAL ACTIVITY. 



In testing for sugars with the polariscope it must be remem- 

 bered that other substances, such as proteins, etc., may be the 

 cause of any observed rotation. 



III. Acetone Bodies. 



The term " acetone bodies" includes acetone, /?-oxybutyric 

 acid and acetoacetic, and this is readily converted into acetone 

 by the loss of C0 2 , so that these acids are never found in the 

 urine unaccompanied by acetone. Acetone may occur, how- 

 ever, when these acids are not present. 



a. Acetone, if present in large amounts, may be tested for 

 in the urine directly. If only small amounts are present, the 

 urine may be distilled. The acetone will go over in the first 



