78 FORMATION OF NITRITES FROM NITRATES 



gives a mixed reaction afterwards when the water is tested for nitrites 

 and nitrates, showing presence of both forms of oxides of nitrogen 

 in air. 



There is no hydrogen peroxide or ozone in air at surface level. 

 The fresh odour in open air, commonly referred to as " ozone." is 

 probably nitrogen peroxide, which at high dilutions has the odour 

 of ozone. The oxides of nitrogen are probably formed by the 

 action of sunlight, rich in ultra-violet rays, in upper regions of the 

 atmosphere upon air and aqueous vapour. 



Attention is drawn to the importance of these actions of light in 

 purification of air and water, and enrichment of soils and waters 

 by this continuous supply of matter essential to organic growth, 

 the energy of which, like that for upbuilding of non-nitrogenous 

 organic compounds, comes from sunlight. 



