382 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



trogen in the soil at the beginning and at the end of the ex- 

 periment would tell whether any nitrogen had been gathered 

 from the air; the increase in the amount of nitric acid would 

 show the amount of nitrogen oxidized, while the decrease in 

 the carbon in the organic matter would be a measure of the 

 oxidation of the latter. 



The general results were, that, 



1st. In the globe containing the woody fibre the total ox- 

 idation of organic matter was greatest. 



2d. In each case there was a considerable increase in the 

 amount of nitric acid during the experiment, showing that 

 nitrogen had been oxidized. The oxidation was less, how- 

 ever, in presence of the woody fibre, showing that the greater 

 oxidation of organic matter had not favored the oxidation of 

 the nitrogen. 



3d. The total amount of nitrogen in the soil in each case 

 did not increase ; whence it appears that the increase in ni- 

 tric acid was at the expense of the nitrogen in the organic 

 matter, and that there the free nitrogen of the inclosed air 

 did not contribute to the formation of nitric acid nor other 

 nitrogenous compounds in the soil. 



This failure of the free nitrogen to become oxidized was 

 not due to a lack of free oxygen in the air, since less than 

 one fourth of the latter was consumed during the experiment. 

 Nor was it to be ascribed to lack of bases with which the 

 nitric acid could combine, since analysis showed that enough 

 of the latter was present to combine with three or four times 

 as much as was present at the end of the experiment. 



"It results from these experiments, therefore, that the free 

 nitrogen contained in a confined portion of the atmosphere, 

 and one which is not renewed, can not take part in the forma- 

 tion of nitric acid which takes place in the soil. Under 

 the circumstances named, nitrification took place only at the 

 cost of the humus substances which exist in every fertile 

 soil." 



This test forms a very interesting supplement to the classic 

 researches of the same savant upon the question whether 

 plants assimilate free nitrogen from the air. The results of 

 these latter, which have been confirmed by experiments of 

 Lawes and Gilbert in England, show that plants do not as- 

 similate the uncombined nitrogen of the air. It appears 



