l8 THEORIES ON THE ABSORPTION OF NITROGEN 



Berthelot showed that even the electricity present at the 

 earth's surface, between soil and atmosphere, was able to 

 convert free nitrogen into nitric acid. He further demon- 

 strated that the micro-organisms are able to assimilate the 

 free atmospheric nitrogen and to deposit it in the albumen 

 (perisperm). 



Boussingault laid stress on the influence which porous 

 bodies exert on the conversion of the nitrogen present in 

 complex organic compounds, into c-.mmonia, and from 

 ammonia into nitric acid. 



Dumas, de Lucas, Gloez, Wolff, Franck, attributed the 

 same facultv to alkalis and alkaline soils. Schloesing, 

 Muntz, Landolt, and others classified bacteria as agents 

 capable of converting organic nitrogen into ammonia and 

 thence into nitric acid. 



Althougli these opinions seemed to confirm, or, at 

 any rate, to lend a semblance of truth to the theory "on- 

 tained in tliis hypothesis, other scientists, on the other 

 hand, published researches which nullified the earlier con- 

 clusions. 



Lawes, Gilbert, and Berthelot found that rain-water, 

 draining off in the deeper soil layers, always contains 

 appreciable quantities of nitric acid. Morgen, Dietzell, 

 vSchloesing, and Warrington showed tiiat a portion of the 

 nitrogen liberated from nitrogenous organic compounds by 

 their conversion into ammonia and nitric acid, is found 

 either as free nitrogen or as nitrogen protoxide. 



Finally, if there exist bacteria which nitrify ammonia, 

 there are others (work of Gayon, Dupetit, Deherain, and 

 Maquenne) w'hich reduce nitric acid to nitrous acid, to oxides 

 and protoxides of nitrogen, and even to free nitrogen. The 

 nitrified substance in the soil may tiuis vary under the 

 influence of all .sorts of different factors, and the Legu- 

 minosie are unable to prevent certain causes of loss which 

 occasion variations in the richness of the soil. It was in 

 the face of all these hypotheses, these theories and con- 



