724 Rural School Leaflet. 



TABLE I ^., p , . 



Nitrogen Protein 



Alfalfa hay 2.29;^ 14-3;^ 



Clover hay • • 1.96 12.3 



Corn fodder with ears 0.72 4.5 



Timothy hay 0.94 5.9 



Nitrogen does not occur in plants as an element but as a compound. 

 The compounds that contain nitrogen are commonly called protein, 

 nitrogenous compounds would be a more accurate name. There are a 

 number of these compounds. On the average they contain about 16 per 

 cent, of nitrogen. When a chemist determines the per cent, of protein 

 he finds the amount of nitrogen and multiplies this by 6j4 to get the per 

 cent, of protein. One of tlie very important constituents of our food is 

 protein. The following table gives the amount of water and protein in 

 a few foods : 



TABLE II w . P . • 



Water Protein 



Green peas 81.8^ 3.4^^ 



Dried peas 9.5 24.6 



Dried beans 12.6 22.5 



Peanuts 9.2 25.8 



Wheat flour 12.1 1 1 .2 



Lean beef 70.0 21.3 



Milk 87.0 3.3 



Eggs y^y.y 14.8 



Potatoes 78.3 2.2 



It will be seen that these legumes contain over twice as much protein 

 as wheat flour. Peas and beans may be used to replace the protein of 

 meat to a considerable extent. They are a little harder to digest, so are 

 not ordinarily used in very large cjuantities except by people who have 

 outdoor work. 



The most important way in which legumes furnish protein for human 

 food is indirectly. Of course, an animal that produces lean meat, eggs, 

 milk, or other product that is high in protein must have much protein in 

 its food. Alfalfa and clover hay are the indirect souice of much of the 

 protein in our milk and meat. 



Problem i. What percentage of nitrogen is there in each of the foods 

 in Table II? 



Problem 2. Another way to compare these is on the basis of dry 

 matter. Green peas contain 81.8 per cent, of water and 3.4 per cent, of 

 protein, or 18.2 per cent, of dry matter of which 18.7 per cent, is protein. 



How much dry matter is there in each of the other foods? What per- 

 centage of the dry matter is protein? 



Protein is only one of several important parts of food. For a discus- 

 sion of the other parts see : 



