34 THE ATMOSPHERE. II. 



amount was greatest in May and June and least in December 

 and January, and that during rain and particularly during 

 violent thunder-storms and gales the amount was often greatly 

 increased. Over marshes or in towns no ozone can be de- 

 tected. 



According to Schone* the indications usually ascribed to 

 ozone are really due to hydrogen peroxide. In 1874 and 1875 

 he made many determinations (in Moscow) of the amount of 

 hydrogen peroxide in rain and snow, also, by artificially pro- 

 ducing hoar frost, in air. He found the maximum amount 

 occurred in air at 4 p.m. and the minimum between midnight 

 and 4 a.m., and that it was most abundant in July and least 

 abundant in December and January.! 



It seems established as a fact that country and sea air con- 

 tains a powerful oxidising agent in small quantity, that this 

 substance, whether it be ozone or hydrogen peroxide, is 

 destroyed by contact with organic putrescible substances, and 

 that the fact of its presence in any particular sample of air is 

 practically an indication of the purity of that air. The popular 

 belief in the health-giving character of " ozone-laden" air is 

 thus seen to possess a real foundation in fact, but not in the 

 way it is generally supposed. The ozone is not of itself 

 important, so far as is known, except as proof of the purity of 

 the air from all readily oxidisable ingredients, and probably 

 from germs of micro-organisms. It has been shown that 

 ozonised air quickly destroys germs in air. | 



According to Bach hydrogen peroxide is present in the 

 leaves of a large number of plants, being produced by the 

 decomposition of carbon dioxide in presence of water by the 

 chlorophyll of the plants. J. Peyrou ; found that ozone (or 

 hydrogen peroxide) w r as evolved from growing plants. He 

 found that more ozone was in nearly all cases to be detected 

 in the air over a field with a growing crop than over a fallow 

 field. He noticed that the amount of ozone was fairly con- 

 stant during the day in August, but that from 6 to 9 p.m. no 

 ozone could be found in the atmosphere. 



* Ber. 1880 [13], 1503. t Abst. in Jour. ('. Soc. 1878, 552. 



J Cbappuis, J.O.S. 1881. abst. 632. J.C.S. 1895, abst, 26 and 239. 



|| C. Rend. 1894, 1206; J.C.S. 1895, abst. ii., 240. 



