26 LABORATORY EXERCISES. 



12. TO TEST FOODS FOR FATS AND OILS. 



Materials : Ground flaxseed, corn-meal, milk, egg, butter, mutton 

 tallow; ether or benzine; beaker-glass, funnel, filter-paper. 



Caution ! Never handle benzine or ether near a flame or a hot 

 stove, since the vapor of these substances is very inflammable. 



A. Method of extracting oils. 



To two or three teaspoonfuls of the ground 

 flaxseed add an equal volume of ether or ben- 

 zine ; stir the mixture and let it stand for ten 

 or fifteen minutes. Filter and place the liquid 

 aside in a good draught of air until the odor of 

 ether or benzine has disappeared. 



1. What kind of substance have you obtained? 



2. What 'is its smell? 



3 . Why is benzine used to remove grease-spots 



from clothing? 



4. In the same way extract the fats from milk; 



from egg ; from corn-meal. 



B. Hold a piece of butter or mutton tallow in a 



spoon over the stove. 



1. What is the effect of heat on fats? 



2. How, then, can you distinguish between a 



piece of fat and a piece of proteid ? 



C. Rub a little of the flaxseed on paper. Hold the 



paper to the light. 



1. What effect does fat have on the paper? 



2. Does starch, sugar, proteid, or water have a 



similar effect? 



3. What, therefore, is a simple way of proving 



the presence of fat ? 



