OXIDATION OF NITROGEN. 465 



A further consequence which would follow from an increase in the 

 amount of C0 2 in the atmosphere and the warmer climate would be a much 

 more abundant and widespread vegetation, and, as pointed out (p. 476), 

 more vegetation means that when oxidized more C0 2 will be concentrated 

 in the soil, and this concentration will lead to an acceleration in the rate 

 of carbonation. Furthermore, the increase in average temperature of the 

 globe will accelerate all other chemical reactions of the belt of weathering. 

 It therefore appears probable that the artificial oxidation of coal will result 

 in some of the most profound and far-reaching geological consequences 

 which are due to the agency of man. 



oxidation of nitrogen. — As already noted, combined nitrogen occurs in various 

 organic compounds, of which the proteids and albuminoids are the more 

 important. The oxidation of this nitrogen, like that of carbon and hydro- 

 gen, is a bio-chemical process, being the joint work of microbes, oxygen, 

 and water. Of the microbes, bacteria are by far of the greatest conse- 

 quence. In the decomposition of the complex nitrogen compounds the 

 nitrogen passes into ammonia, nitrites, nitrates, and, to some extent, free 

 nitrogen. The first stage of the process is the transformation into ammonia. 

 In the case of urea, Fischer gives the reaction as follows:" 



CO(NH 2 ),+2H 2 = C0 3 ( NH 4 ) 2 



The second stage of the process is the transformation of the ammonia into 

 nitrites, and the final stage is the transformation of the nitrites into nitrates. 

 Each of these stages of work is accomplished by certain bacteria which 

 take no part in the other stages. At the same time the nitrogen is oxidized 

 the carbon and hydrogen of the nitrogen compounds are oxidized into 

 carbon dioxide and water, preciselv as in the case of cellulose. 



So far as the nitrogenous compounds are concerned, the ultimate 

 geological products which remain in the soil are the nitrates, although in 

 the process some small part of the nitrogen is freed and lost, as already 

 noted. * 



Apparently nitrates are produced on a far vaster scale in the tropical 

 regions than in the temperate regions. Miintz and Marcano state that in 



" Fischer, fit., p. 103. 



>> Fischer, cit., pp. 98-106. See, also, Conn, H. W., The story of germ life, D. Appleton & Co., 

 New York, 1897, pp. 104, 118; and Aikman, C. M., Manures and manuring, Wm. Blackwood & Sons, 

 London, 1894, pp. 167-170. 



MON xlvii — 04 30 



