URINE. 339 



of a red color, cool the tube under running water and transfer to 

 an evaporating dish or beaker. Make the mixture slightly alka- 

 line with solid potassium hydroxide, return it to a test-tube, add 

 2-3 c.c. of acetic ether and shake the tube vigorously. In the 

 presence of laevulose the acetic ether is colored yellow. 



The only urinary constituents which interfere with the test are 

 nitrites and indican and these interfere only when they are simul- 

 taneously present. Under these conditions, the urine should be 

 acidified with acetic acid and heated to boiling for one minute to re- 

 move the nitrites. In case the indican content is very large, it will 

 impart a blue color to the acetic ether, thus masking the yellow color 

 due to laevulose. When such urines are to be examined, the indi- 

 can should first be removed by Obermayer's test (see p. 281). The 

 chloroform should then be discarded, the acid-urine mixture diluted 

 with one-third its volume of water and the test applied as described 

 above. The urine of patients who have ingested santonin or rhu- 

 barb, respond to the test. The test will serve to detect laevulose 

 when present in a dilution of i : 2000 i. e., 0.05 per cent. 



2. Seliwanoff's Reaction. To 5 c.c. of SeliwanofFs reagent 1 

 in a test-tube add a few 7 drops of the urine under examination and 

 heat the mixture to boiling. The presence of laevulose is indicated 

 by the production of a red color and the separation of a red precipi- 

 tate. The latter may be dissolved in alcohol to which it will impart 

 a striking red color. 



If the boiling be prolonged a similar reaction may be obtained 

 with urines containing dextrose. 



3. Phenylhydrazine Test. Make the test according to direc- 

 tions under Dextrose, i, page 306. 



4. Polariscopic Examination. A simple polariscopic examina- 

 tion, when taken in connection with other ordinary tests, will fur- 

 nish the requisite data regarding the presence of laevulose, provided 

 Isevulose is not accompanied by other laevorotatory substances, such 

 as conjugate glycuronates and /3-oxybutyric acid. 



CHOH 



//\ 

 HOHC CHOH 



INOSITE, 



HOHC CHOH 



V 



CHOH 



1 Seliwanoff's reagent may be prepared by dissolving 0.05 gram of resorcin in 

 100 c.c. of dilute (1:2) hydrochloric acid. 



