4 THE CHEMISTBY OF THE FARM 



plant, as much right to be called " organic " as 

 albumin or cellulose. 



In the following table will be found the average 

 composition of a crop of meadow grass weighing five 

 tons when cut, and producing one and a half tons of 

 hay ; this will illustrate what has just been said as to 

 the constituents of plants. Further information as 

 to the composition of crops will be found on pp. 14 

 and 72. 



COMPOSITION OF A CROP OF MEADOW GRASS. 



Water .. 

 Carbon . . « . 

 Hydrogen 



Nitrogen 



Oxygen and Sulphur 



Potash . . 



Soda . . 



Lime . . 



Magnesia 



Oxide of Iron . . 



Phosphoric acid 



Sulphuric acid 



Chlorine . • 



Silica .. 



Sand, &o. 



1,316 



144 

 49 

 1,105 

 66 

 11 

 28 

 10 



12 

 10 

 16 

 67 

 4. 



Combustible matter 



8,378 Ibg. 

 2,613 lbs. 



Ash 



209 lbs. 



11,200 lbs. 



Total crop 



Plants obtain the elements of which they are built 

 up partly from the soil and partly from the atmo- 

 sphere. From the soil they obtain by means of their 

 roots all their ash constituents, all their sulphur and 

 phosphorus, and, in most cases, nearly the whole of 

 their nitrogen and water. From the atmosphere they 

 obtain, through the instrumentality of their leaves, the 

 \\hole, or nearly the whole, of their carbon. The 



