CHEMICAL ANALYSIS OF COEN. 79 



phosphoric acid. If, on the other hand, his corn is 

 planted primarily and chiefly for the grain, he learns 

 that phosphoric acid is required in a proportion nearly 

 equal to that of all the other elements together, and 

 that next to this in importance are potash and soda. 



An inspection of these tables will also throw some 

 light upon the relative feeding values of corn-stalks, 

 and the straw of the other included grains, as well as 

 upon the comparative nutritive values of the grains 

 themselves. 



The proportion of ash contained in any plant or 

 grain represents the amount of inorganic matter 

 that enters into its composition. When the plant is 

 burned, all the other constituents, amounting gener- 

 ally to over ninety per cent, of the entire weight, dis- 

 appear. We are thus able to determine what grains 

 contain the smallest proportion of inorganic matter, 

 and are consequently least exhausting to the mineral 

 elements of the soil. f; . . 



In the following table, Prof. Johnston has given 

 the quantity of ash yielded by one thousand pounds 

 of each of the plants named : 



Indian Corn 15 Ibs. Corn-stalks 50 Ibs. 



Wheat straw 50 " 



Barley " 50 " 



Wheat 20- 



Barley 30 



Oats 40 



Eye 20 



Peas.. ...30 



Oat " 60 < 



Eye " 40 " 



Pea " ..50 " 



The investigations of Dr. Jackson, of Boston, in 

 regard to the properties of corn, are equally curious 

 and instructive. Among other interesting facts, he 



