4 LABORATORY WORK IN PHYSIOLOGICAL CHEMISTRY. 



with characteristic crystalline forms, solubilities, and melt- 

 ing-points. 



GLUCOSE = DEXTROSE = GRAPE-SUGAR. 



Of the monosaccharides, dextrose holds first place in 

 importance in the animal economy. Examine and taste the 

 dry substance. Test its solubility in water and in hot and 

 cold alcohol. In the following tests make use of a 1 per cent 

 solution: 



(a) Moore's Test. To 5 c.c. of the dextrose solution add 

 an equal volume of NaOH, and heat. The mixture becomes 

 yellow and finally brown, due to the formation of caramel. 

 This test lacks delicacy and reliability in examining urine. 



(6) Trommer's Test. To 5 c.c. of the dextrose solution 

 add an equal volume of NaOH. Then add, drop by drop, a 

 dilute solution of CuS0 4 (so dilute that the green color is just 

 visible) until a trace of permanent precipitate remains. The 

 solution should be deep blue in color. Warm the upper part 

 of the solution and note result. Write all the equations for 

 the reactions taking place in this experiment. 



(c) Fehling's Test. Heat 5 c.c. of Fehling's solution just 

 to boiling and add a few drops of the dextrose solution. Con- 

 tinue the boiling until the solution commences to respond as 

 with Trommer's test. Compare the reactions of this test 

 with those of the previous ones. 



(d) Barfoed's Test. To 5 c.c. of Barfoed's reagent add a 

 few drops of the dextrose solution and boil. Note the result 

 and write equations. 



(e) Nylander's Test. To 5 c.c. of the dextrose solution add 

 10 drops of Nylander's reagent and boil. The solution grad- 

 ually turns yellow and finally black, bismuth being precipi- 

 tated. 



