41 



in the atmospheric air. Its balance, how preserved. 

 The relation between nitrogen and our edible crops. 



IT was mentioned before that the organic parts 

 of plants consist of four elements one of which is 

 Carbon, which we find in its purest state in the 

 diamond ; and three are gases, namely, Hydrogen, 

 Oxygen, and Nitrogen. The combustible nature 

 of these organic parts, and their easy conversion 

 into gaseous compounds which escape into the 

 atmosphere, give us the clue whence these substances 

 have been obtained, and where we have to seek 

 for them, on the basis of that great law governing 

 animal and vegetable life, that whenever vital 

 power has ceased to exist, all the elements will, 

 under ordinary circumstances, return whence they 

 came earth to earth, air to air. 



Most exhaustive experiments have proved that 

 plants are incapable of absorbing in a pure state 

 these four elements which constitute their organic 

 parts : a plant may be set in pure carbon, supplied 

 with pure oxygen, hydrogen, and nitrogen, and 

 will yet die for want of nourishment. Therefore, 

 as already observed, no plant can absorb and assi- 

 milate these substances in their elementary form ; 

 it is only from certain, now well-known, compounds 

 that it is able to abstract them ; and these great 

 suppliers of all organic plant-food are Carbonic Acid, 

 Water, and Ammonia. 



