94 LESSONS IN AGRICULTURE 



Practical Exercises 



NOTE. The practical exercises on this subject follow 

 as separate lessons. 



LESSON XVIII 



TEST FOR FOOD COMPOUNDS 



(a) To test for the presence of starch in such car- 

 bohydrates as corn, oats, wheat, or rye, pulverize a few 

 seeds, pour over them a little boiling water, let stand 

 a short time, and add a drop of iodine. If the seeds 

 contain starch the water will turn blue or black in a 

 short time. If the seeds contain sugar it may be de- 

 tected by chewing them slowly and thoroughly. A 

 sweet taste will indicate the presence of sugar. 



(b) To test for protein, remove the germ from a 

 kernel of corn and scorch it on the stove. If it gives 

 off the odor like that of burning feathers, it contains 

 protein. All seeds contain protein. Test other seeds 

 for protein. 



(c) To test for fats or oil, crush seeds or nuts on a 

 piece of clean white paper. Heat the paper gently, be- 

 ing careful not to scorch it. The grease spot that ap- 

 pears will indicate the presence of oil. 



It might be a profitable exercise to make collections 

 of feeding stuffs, and classify them into fats, protein, and 

 carbohydrates. 



