180 



Transformation of Nitrogen 



with ammonia and in the presence of ferric hydrate. Ammonia is 

 also oxidized to nitrite by ultraviolet radiation. According to Weith 

 and Weber, hydrogen peroxide and ammonia react with each other, 



120 



8.0 1 9.0 

 NaHCOj 

 Reaction -pH 



10.0 I 

 Na.,CO 



11.0 



100 



Free H. CO3 

 Fig. 77. Influence of reaction upon nitrate formation (from Meyerhof). 



giving rise to nitrous acid. The interaction between ozone and am- 

 monia to give ammonium nitrate has been known for several decades: 



(NH3)2 + 4O3 



NH4N02 + H202 



NH4N02 + H202 + 402 



NH4NO3 + HoO 



It has been reported recently that oxidation of ammonia and 

 its salts in solution and in soil may be effected by sunlight, in the 

 presence of certain photosensitizing substances, TiO and ZnO being 

 most active; basicity favored oxidation and acidity impeded it ( Table 

 40). It was believed that a part of the nitrification in soil is due at 

 least to photochemical oxidation at the surface of xarious photo- 

 catalysts present in the soil. The process was believed to be of 

 special importance in tropical countries, such as India (Dhar). Rossi 

 also suggested that the process of nitrification is of a purely physico- 



