244 



GENERAL SCIENCE 





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The flavor of the tonka bean to some extent resembles that of 

 the vanilla bean, but it is cheaper and inferior. It may be de- 

 tected by its pungent odor. 



Olive Oil. Olive oil is some- 

 times adulterated with cotton- 

 seed oil or other cheaper oils. 



Experiment. Add 5 c.c. of nitric 

 acid to 5 c.c. of oil in a test tube. 

 Shake. Pure olive oil turns from 

 pale to dark green in a few minutes. 

 If it changes to red, white, orange, 

 yellow, or rose, foreign oil was 

 added. Olive oil, on standing, be- 

 comes a yellow solid. 



The following table will 

 show how to detect what oil the 

 olive oil was adulterated with : 



FIG. 149. Three Bottles of Extract 

 (front and side views). 



This shows the impossibility of correctly esti- 

 mating the quantity of contents from apparent 

 size of the container. The bottle which is appar- 

 ently smallest holds the most, and vice versa. 



BACH'S TABLE FOR OIL REACTIONS 



Honey. Sometimes glucose is used to adulterate honey. 



Dissolve by heating three teaspoonfuls of honey in an equal amount of 

 water. Cool and add a few drops of a dilute solution of potassium iodide. 

 The honey should remain pale, if pure. If the color is removed, glucose was 

 added. If starch was added, a blue to purple coloration will appear. 



Tests of Food Adulterations (reference books). A splendid book on food 

 analysis is published by D. Van Nostrand Co., Detection of Common Food 

 Adulterants, by Edwin M. Bruce; Elementary Applied Chemistry, Lewis B. 

 Allyn, is another good book, published by Ginn & Co. 



