26 THK PLANT. 



Liebigsajs: "All the nitrogen of plants and of 

 animals is derived from the air. Every fireplace 

 Avliere coals are burned, the numerous furnaces and 

 chimneys of the manufacturing towns and districts, 

 of locomotive engines and steamboats, all the smelt- 

 ing furnaces of the iron-works — all these are so many 

 forms of distillatory apparatus which enrich the at- 

 mosphere with the nitrogenized food of a vegetable 

 world, belonging to a period long past, 



" We can form some idea of the quantities of am- 

 monia thus poured into the atmosphere, if we con- 

 sider that in numerous gas-works many tons of am- 

 moniacal salts are annually obtained from the coals 

 distilled for gas." * 



The same is true of any of the atmospheric or 

 earthy constituents of plants. They are performing 

 their natural offices, or are lying in the earth, or 

 floating in the atmosphere, ready to be lent to any 

 of their legitimate uses, sm-e again to be returned to 

 their starting point. 



Thus no atom of matter is ever lost. It may 

 change its place, but it remains for ever as a part of 

 the capital of nature. 



* Journal of the Royal Agricultural Society, vol. xv'n., p. 289. 



