THE SOURCES OF THE NITROGEN OF VEGETATION, ETC. 459 



7. M. G. Ville's experiments conducted wider the superintendence of a Commission 

 comprising MM. Dumas, Kegnault, Paten, Decaisne, Peligot, and Chevkeul. 



These experiments were conducted at the Museum d'Histoire Naturelle, Jardin des 

 Plantes, Paris, in the autumn of 1854. M. Cloez was appointed to assist M. Ville; 

 and M. Chevkeul reported on behalf of the Commission, in 1855*. 



In an apparatus similar to that employed in the experiments of M. Ville which have 

 been already described, three pots of Cress were placed. The soil consisted of ignited 

 brick and sand, to which was added some of the ash of the plant. Carbonic acid 

 was supplied artificially ; and the plants were watered with distilled water. The Cress 

 in one of the pots did not thrive well; and, in this case, analysis showed a loss of 

 2 milligrammes of Nitrogen. In one of the other cases, there was a gain of 0-0492 

 gramme of Nitrogen, upon 0-0038 gramme supplied in the seed; and in the other, 

 there was a gain of 0-0071 gramme of Nitrogen, upon 0-0039 gramme contained in the 

 seed. 



At the suggestion of one of the members of the Commission, a smaller vessel was also 

 attached to the aspirator, in which one pot sown with Cress was placed. The soil being 

 duly watered with distilled water, the apparatus was then closed, and not opened (as 

 the other frequently was) until the conclusion of the experiment. In this case also, 

 there was a considerable gain of Nitrogen indicated, namely, 0-0287 gramme gain, upon 

 0-00G3 gramme in the seed. 



Unfortunately, an element of uncertainty attached to the evidence afforded by these 

 experiments made under the superintendence of the Commission, which is very much to 

 be regretted. A quantity of distilled water taken from the same bulk as that used for 

 watering the experimental plants was saved for analysis. The examination of this 

 water devolved on M. Cloez ; who, unfortunately, was called away for some days, during 

 the evaporation of the water with oxalic acid, with a view to the after-determination of 

 any ammonia it might contain. M. Peligot determined the ammonia in the acid residue 

 of the evaporation of this water, as well as in that of the water removed from the cases, 

 after it had served in the experiments. The result was, that there was indicated such 

 an excess of ammonia in the water before being used, over that in the residual water 

 after removal from the larger case, as more than covered the increase in the Nitrogen 

 of the plants over that in the seeds sown. M. Cloez found, however, that, in his 

 absence, the evaporation of the water had been conducted by the side of ammoniacal 

 emanations from other processes. But when new portions of the original water were 

 evaporated with proper precautions, less ammonia was indicated in it than in the water 

 at the close of the experiment ; and then, also, a gain of Nitrogen by the plants in the 

 larger apparatus was indicated. 



At any rate, however, the result with the single pot, in the small apparatus, showed 

 a considerable gain of Nitrogen, even supposing the first analysis of the supplied water 

 to be correct. 



* Compt. Eend. 1855. 



