EXERCISE 35. THE SWELLING TEST FOR LINSEED MEAL 



Pulverize a small amount of the meal and place a level teaspoonful of 

 it in a tumbler; add 10 teaspoonfuls of boiling hot water to the meal. Stir 

 thoroughly and allow to settle. Old-process meal will remain jelly-like on 

 standing, while the new-process meal will settle in the course of an hour and 

 leave a clear yellowish solution on top. See FIG. 38 in Productive Feeding. 



About what proportion of clear water is left on top in case of each sample? 



Test for starch: Add a few drops of iodine solution to the clear liquid in 

 each tumbler and note the color. Is starch present in either case? 



A more delicate test for starch may be made by placing a very small 

 amount of the finely pulverized meal on a slide, mixing it with a couple of 

 drops of distilled water, and adding a drop of iodine solution. Examine under 

 microscope for blue-colored specks. Starch is not present in meal made from 

 clean, well-matured flaxseed. 



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