14 CHEMICAL PHYSIOLOGY. 



stratum below. If no sugar be present, only a black colour 

 may be obtained (Trommer's Test). 



(c.) To the solution add Fehling's solution; boil = a 

 yellow or yellowish-red precipitate of hydrated cuprous 

 oxide. 



[For the precautions to be observed in using Fehling's solution, 

 and for other tests for glucose, see " Urine."] 



7. V. Maltose, 12 H 22 O n . 



(a.) Take 1 grm. of ground malt, mix it with ten times 

 the quantity of water, place the mixture in a beaker, and 

 keep it at 60C. for half an hour. Then boil and filter ; the 

 filtrate contains maltose and dextrin. 



(5.) Test for a reducing sugar with Fehling's solution or 

 other suitable test. (See also " Salivary digestion.") 



8. VI. Lactose, C 12 H 22 O n + H 2 O (see " Milk ). 



9. VII. Cane Sugar, C 12 H 22 O n . 



(a.) Observe its crystalline form and sweet taste. 



(b.) Its solutions do not reduce Fehling's solutions (many 

 of the commercial sugars, however, contain sufficient grape- 

 sugar to do this). 



(c.) Place some cane-sugar in a beaker, pour on it strong 

 sulphuric acid, and add a few drops of water ; soon the whole 

 mass is charred. 



(d.) Inversion of Cane-Sugar.- Boil a strong solution of 

 cane-sugar in a flask with one-tenth of its volume of strong 

 hydrochloric acid. After prolonged boiling the cane-sugar 

 is " inverted," and the solution contains a mixture of 

 dextrose and laevulose. Test its reducing-power with 

 Fehling's solution. 



10. Conversion of Starch into a Reducing Sugar. Place 50 cc. 

 of starch solution in a flask on wire gauze over a Bunsen burner, 

 add one drop of strong sulphuric acid, and boil for five to ten 



