310 URINE. [CH. XII. 



from the normal, but such cases should -be examined by the application of 

 Benedict and Osterberg's quantitative method. ^x.. 407 J 



The osazone test serves to confirm the presence of glucose in doubtful 

 cases, and especially to distinguish between glucose on the one hand and 

 lactose and pentoses on the other. 



The fermentation test is helpful in connexion with the recognition of 

 lactose and glycuronic acid. 



380. Benedict's test. To 5 cc. of Benedict's reagent (see 

 p. 107) in a test-tube add eight drops of the urine. Boil vigorously 

 for two minutes and allow to cool spontaneously. If glucose is 

 present the entire body of the solution will be filled with a precipitate 

 which may be red, yellow or green in colour, depending on the 

 amount of sugar. 



NOTE. It is essential to add a small volume of urine. If too much be 

 added the results are apt to be ambiguous. Even with the eight drops 

 recommended, a slight precipitate of earthy phosphates may appear and 

 simulate a feeble reduction. 



381. Cole's test for small amounts of glucose in urine. In 



a dry boiling tube or large test-tube place about I gram, of adsorbent 

 charcoal. Add 10 cc. of the urine, shake, heat to boiling and then 

 cool under the tap. Shake at intervals for 5 minutes. Filter 

 through a small paper into a dry test-tube. To the filtrate add 4 

 drops of pure glycerol and 0-5 gram, of anhydrous sodium carbonate. 

 Shake and heat to boiling. Maintain the boiling for exactly 50 sees. 

 Immediately add 4 drops of a 5 per cent, solution of crystalline 

 copper sulphate, shake to mix and allow the tube to stand without 

 further heating for one minute. With normal urine the fluid 

 remains blue. If glucose is present to the extent of 0*03 per cent. 

 above the normal amount in urine the blue colour is discharged and 

 a yeUowish precipitate of cuprous hydroxide forms. 



NOTES. i. Treatment with adsorbent charcoal removes practically the 

 whole of the urates, creatinine and pigments that interfere with Fehling's test. 

 It also adsorbs so much of the normal amount of glucose present that the 

 nitrate from normal urine fails to give a reduction. 



2. 0-5 gram, of anhydrous sodium carbonate is carried by about f the 

 length of a large blade well piled up once. 



3. Should the specific gravity of the urine exceed 1025 it is advisable to 

 use 5 cc. of the urine + 5 cc. of water. 



4. The test is not given by chloroform nor by glycuronates : it is given by 

 pentoses. 



