Nitrates in Aqueous Solution by the Action of Sunlight. 167 



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, whicli 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 purifica- 

 tion 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. 



EEFEEENCES. 



(1) Moore and Webster, ' Eoy. Soc. Proc.,' B, vol. 87, p. 163 (1913). 



(2) Moore, ibid., 1914, p. 556. 



(3) Moore, ' Recent Advances in Physiology and Bio-chemistry,' edited by Leonard Hill, 



p. 29, et seq., and p. 131. Arnold, London, 1906. 



(4) MendeleefF, ' Principles of Chemistry,' translated by Kemensky and Pope, vol. 1, 



p. 287. Longmans, London, 1905. 



(5) Ilosvay, 'Bull. Soc. Chim.' [3], vol. 2, p. 666. 



(6) Ilosvay, 'Ann. Chem. Pharm.,' vol. 124, p. 1 ; vol. 186, p. 2. 



(7) Hayhurst and Pring, ' Chem. Soc. Trans.,' vol. 97, Pt. I, p. 868 (1910) ; Pring, ' Roy. 



Soc. Proc.,' A, vol. 90, p. 204 (1910), and Strutt, ' Roy. Soc. Proc.,' A, vol. 94, 

 p. 260 (1918). 



(8) Sutton's 'Volumetric Analysis,' 10th edition, p. 470. Churchill, London, 1911. 



