THE SOUECES OF THE NITKOGEN OF VEGETATION, ETC. 455 



in the soil an amount of carbonate of potash very nearly corresponding in potash to 

 the amount of nitrate of potash which would represent the observed loss of Nitrogen. 

 He concluded that nitrate had been decomposed in the soil, by the organic matter of 

 the debris of the seeds and of the roots, and that Nitrogen had been evolved. If Ave 

 clearly understand this explanation of the loss of Nitrogen of the nitrate, we would 

 suggest that it would seem to require for its validity that the plant should have assimi- 

 lated potash from the nitrate exactly corresponding in amount to the Nitrogen it fixed 

 from the same source. 



From the results of these experiments with nitrate, Boussingault chew the following 

 conclusions : — 



1. That there was no assimilation of free Nitrogen. 



2. That there was a loss of supplied Nitrogen, either from the soil, or by the plant. 



3. That, in the two cases, the amount of carbon assimilated bore a close relation to 

 that of the Nitrogen taken up by the plant. 



It is seen, then, that the results of the laborious investigations of Boussixgault, 

 extending at intervals over a period of more than twenty years, have led him to con- 

 clude that, neither Leguminous plants, nor the others experimented upon, were able, 

 either when their supplies of combined Nitrogen were limited to that contained in the 

 seed sown, or when their vigour of growth was stimulated by artificial supplies of com- 

 bined Nitrogen, to assimilate the free or uncombined Nitrogen of the atmosphere. 



B. — M. G. Ville's Experiments*. 



1. M. G. Ville's determinations of the Ammonia in the atmosphere. 



M. G. Ville, of Paris, commenced his investigations, on the subject of the assimilation 

 of Nitrogen by plants, in 1849. He first sought to determine the proportion of 

 Ammonia in the atmosphere. To this end, he aspired known quantities of air through 

 acid, and determined the amount of ammonia absorbed. He operated upon very much 

 larger volumes than previous experimenters had done. His results show, moreover, a 

 much smaller proportion of ammonia in the air than those of others. 



The air of Paris, during part of 1849 and part of 1850, gave a mean of only 0-0237 

 part by weight of ammonia, to 1,000,000 parts by weight, of air; and that of the 

 suburbs of Paris, during some period of 1852, gave 0*0211 parts of ammonia, to 

 1,000,000 parts of air. 



2. M. G. Ville's general plan of experimenting on the question of the assimilation 



of Nitrogen by jilants. 

 M. G. Ville employed specially-made porous flower-pots, and used, as soil, washed 



* Keeberclies Experiinentales sur la Vegetation, par M-. Georges Ville. Paris, 1853. 

 MDCCCLXI. 3 R 



