EXPERIMENT 70. TO DETECT THE PRESENCE OF FAT 

 AND OIL IN FOODS 



(a) Soak some finely chopped alkanna root in alcohol 

 for a short time. Filter off the extract and dilute it with 

 several times the quantity of water. 



(b) Heat a portion of the diluted extract almost to the 

 boiling point, then allow it to cool and note the color. 



(c) Into another test tube containing dilute alkanna ex- 

 tract put a few drops of olive oil. Heat the mixture, allow 

 to cool, and note the brilliant red hue acquired by the oil 

 globules. Any substance which contains oil will turn 

 heated alkanna extract red. 



(d) By means of alkanna extract test chocolate, corn- 

 meal, and soap for oils. 



(e) In similar manner test candy of -a cheap grade; 

 candy of the same kind but of the best grade. 



If the tests show that both the cheap and the expensive 

 candy specimens contain fatty substances, should you think 

 that the fats were the same in the two cases ? 



What possible fats might be present in the best grades 

 of confections ? What fats are probably present in the 

 cheap grades of confections ? 



EXPERIMENT 71. TO DETECT ARTIFICIAL COLORING MAT- 

 TER IN FOODS 



(a) Boil strips of woolen cloth first in a dilute solution 

 of soda and then in water. By this treatment, greasy mat- 

 ter and foreign substances are removed from the cloth, 

 and it is made clean. 



(b} Dilute some commercial catchup, wine, jam, or jelly 



