280 ANNUAL OP SCIENTIFIC DISCOVERY. 



their advantage, a portion of this gaseous azote which forms the greatest 

 part of the atmosphere ? The importance of the question is evident : if 

 the free and gaseous azote may directly enter into vegetable organism 

 without passing through some intermediate combination, the veritable 

 source of agricultural wealth is in the atmosphere; if, on the contrary, 

 before the azote commingles with the plant, it must unite itself to some 

 other element, the agricultural chemist must turn his attention to the 

 search of some new and better method of favoring the slow and difficult 

 formation of combinations of azote. In both of the hypotheses the im- 

 portance of manure remains incontestable, but their functions will not be 

 so important. If azote gas is not capable of assimilation, if it is simply 

 destined to temper the action of the oxygen with which it is mixed in the 

 air, it is evident how important organic matters are in manures, bringing 

 as they do the elements of the azotic principles elaborated by the plants. 

 If, on the contrary, the azote of air is absorbed during the act of vegeta- 

 tion, if it becomes in this way an integral part of the vegetable, then the 

 mineral substances of manures contain the greatest part of their fertilizing 

 properties ; for the azote element would have been abundantly furnished 

 by the atmospheric air. Why, then, has the chemist not yet determined 

 this important point, whether gaseous azote is or is not directly assimilated 

 by plants ? The great obstacle lies in the difficulties of making the ex- 

 periment, which should resolve the question. When the chemist would 

 place a plant under a definitive regimen, to ascertain what it obtains from 

 the mineral kingdom, whence it extracts a portion of its aliment, it is 

 indispensable to measure, to weigh, to analyze every thing the air it 

 respires, the water which moistens it, the soil which upholds. M. Bous- 

 singault and M. Ville use different methods, of which they are tenacious. 

 It cannot be denied that M. Boussingault exhibits a great deal of art in 

 the process he used in his experiments. He first abandoned the ridicu- 

 lous pretension commonly entertained . before him of measuring by 

 default the azote a plant would have absorbed while it lived during a cer- 

 tain time in a limited quantity of air. He substituted in its stead, raising 

 the plants in a completely sterile soil, and comparing the composition of 

 the seed and the composition of the small crops so obtained at the expense 

 of air and water alone. A handful of earth previously calcined, and 

 watered with distilled water, evidently can furnish no organic matter to 

 the plant which is developed there ; and consequently, if, after the crop 

 is gathered, the chemical analysis shows it contains more azote than the 

 grains sown contained, it is manifest that this azote came by the air this 

 result M. Boussingault obtained by experimenting with the seed of clover 

 and of peas. 



But in communicating this result to the world, M. Boussingault did 

 not pretend to do more than to exhibit the bare fact. He made no de- 

 duction to demonstrate that it came by the air in its normal state, or by 

 the rare ammoniacal vapors from which the atmosphere is never exempt. 

 M. Ville did not imitate his silence. He studied the question, and found 



