262 EXPERIMENTAL PHYSIOLOGY. 



1. Carbohydrates. 



(a) Test cane sugar with Fehling's Soln. Boil with dil. HC1 

 and repeat test. 



(b) Molisch reaction. Place 5 c.c. con. H 2 SO4 in a test tube. 

 Incline this tube and pour in gently 5 c.c. of solution to be tested 

 to which two drops of Molisch's reagent has been added. Red to 

 violet zone at point of contact of the two liquids indicates a sugar. 



2. Protein. 



(a) Xanthoproteic Reaction. Add cone. HNO 3 . Heat. Cool- 

 should turn yellow add NHUOH carefully in excess. Yellow 

 deepens to orange. Use egg white coagulated. 



(b) Biuret. Add cone. KOH, mix thoroughly and add few 

 drops dilute CuSC>4. Purple or violet colour indicates protein. Use 

 egg white. 



3. Fats. 



Rub butter, suet, and a peanut or walnut kernel on a piece 

 of ordinary writing paper. A translucent spot appears. This is 

 not removed by heating (cf. essential oils as oil of cloves, winter- 

 green, etc.), nor will it wash off with water (cf. glycerine). 



D. Test samples of the various foods which go to make up an 

 average meal, e.g., bread, meat, potatoes, a vegetable, etc., for 

 the three classes of foods. Write the results in the form of a table 

 indicating presence by +, absence by . 



