PHYSIOLOGICAL CHEMISTRY 449 



Tests for Dextrose in the Urine. The tests for dextrose*, as 

 described, can, with slight modifications, be applied to its detection 

 in urine. 



The most important of these are : 



EXPERIMENT VII. Fehling's Test. Boil 5 c.c. of Fehling's solution 

 in order to ascertain that the Rochelle salt which it contains has not 

 decomposed into reducing bodies. If no reduction occur, add a drop 

 of the suspected urine and boil again. If no result, go on adding 

 small quantities, boiling between each addition, till 5 c.c. have been 

 added. 



Fehling's test is quite satisfactory, when sugar is present in 

 considerable quantity. When the amount of reduction is small, 

 however, it may be due to the presence of other substances than 

 sugar. In such cases the following tests should be applied, as they 

 are positive for sugars only. 



EXPERIMENT VIII. Boettger's Test. To 10 c.c. urine add 1 c.c. 

 Ny lander's reagent. 1 Heat for five minutes on the water bath. If 

 sugar is present to the extent of at least 0*08 per cent., a black 

 precipitate of bismuth forms. 



EXPERIMENT. Worm Miiller Test. 2 In one test tube mix 1 c.c. 

 copper solution and 2 '5 c.c. alkaline Rochelle salt solution. Place 

 2 - 5 c.c. urine in another test tube. Bring the contents of both test 

 tubes simultaneously to the boil. After allowing to cool for 25-30 

 sec. pour the blue reagent into the urine and without shaking place 

 the test tube on the rack. In the presence of a pathological amount 

 of dextrose, a finely suspended yellow precipitate will develop within 

 10 minutes. If the solution should turn red but no precipitate develop 

 the result is negative ; in such a case repeat the test, using 3 c.c. of 

 copper solution. 



Though not so delicate, the following tests are valuable, in that 

 they indicate the nature of the sugar : 



1. The Fermentation Test. EXPERIMENT IX. Place some diabetic 

 urine in a small beaker, and boil it on a sand bath for ten minutes, 

 to expel any air it may contain. Cool the urine and test its reaction ; 

 if alkaline, render faintly acid with a weak solution of tartaric acid. 

 (This precaution is necessary in order to prevent putrefaction, which 

 would lead to the evolution of ammonia.) Add a small piece (about 



1 Nylander's solution : dissolve 4 grm. Rochelle salt in 100 grm. of a caustic 

 soda solution of T12 sp. gr. ; add 2 grm. Bismuth subnitrate and heat on water 

 batli until it is dissolved. 



2 Worm Miiller solutions: 1, 2'5 % solution of copper sulphate; 2, Dissolve 

 10 grm. of Rochelle salt in 100 c.c. of a 4 % solution of caustic soda. 



2F 



