GLUCOSE 59 



due to a 500 c.c. Kjeldahl flask by means of 25 c.c. of water and 

 25 c.c. of concentrated HNOs. Add 0.2 gm. of copper nitrate, 

 a couple of pebbles or glass pearls and boil very gently for four 

 and one-half hours over a micro-burner. Fit the necks of the 

 flasks with condensers of the Hopkins type made from large 

 test-tubes fitted with two-hole rubber stoppers, the inlet tubes 

 extending near the bottom of the test-tubes while the outlet tube 

 is shorter. These condensers should fit rather loosely. A good 

 current of water flowing through the condensers prevents loss 

 of benzoic acid or change in concentration of the nitric acid. 



After cooling, rinse the condensers down with 25 c.c. of water 

 and transfer the contents of the flask to a 500 c.c. separatory 

 funnel, with the aid of 25 c.c. more of water. The total volume 

 of the solution is now 100 c.c. Add to the solution sufficient 

 ammonium sulphate to just saturate it (about 55 gms.). Make 

 four extractions with freshly washed chloroform, using 50, 35, 

 25, and 25 c.c. portions. The first two portions may be used to 

 further rinse out the Kjeldahl flask. 



Collect the successive portions of chloroform in another sepa- 

 ratory funnel. Add to the combined extracts 100 c.c. of a satu- 

 rated solution of pure sodium chloride, to each liter of which has 

 been added 0.5 c.c. of concentrated HC1. Shake well, draw the 

 chloroform into a dry 500 c.c. Erlenmeyer flask and titrate with 

 N/10 sodium alcoholate, using 4 or 5 drops of phenolphthalein 

 as an indicator. The first distinct end point should be taken, 

 although it may fade on standing a short time. 



Calculation. Multiply the number of cubic centimeters of 

 alcoholate used by the factor for hippuric acid as determined by 

 standardization to obtain the amount of hippuric acid in the 

 100 c.c. of urine used. One c.c. of exactly N/10 sodium alco- 

 holate is equivalent to 0.0179 gm. of hippuric acid. Calculate 

 the daily output of hippuric acid from the twenty-four hour 

 volume. 



GLUCOSE 



Fehling's Method 



Principle. Diluted urine is run into a measured amount of 

 Fehling's solution at the boiling-point until all of the copper it 

 contains is reduced as indicated by the loss of blue color. This 



