1254 PHYSIOLOGY 



these sugars will reduce Fehling's solution it becomes important to 

 be able to distinguish between them. 



The following tests are used for the detection of abnormal amounts of sugar 

 in the urine : 



(1) FEHLING'S TEST. The urine is boiled with Fehling's solution (an 



FIG. 519. Glucosazone. 



alkaline solution of copper sulphate to which Rochelle salt has been added to 

 keep the cupric hydrate in solution). Under the action of glucose or lactose the 



FIG. 520. Lactosazone. (PLIMMER.) 



cupric hydrate is reduced to an insoluble cuprous hydrate, which forms a yellow 

 or red precipitate. 



(2) The phenylhydrazine test may be carried out as follows : 2 c.c. of 50 per 

 cent, acetic acid, saturated with sodium acetate, and two drops of phenylhydra- 



