XXVI 

 SEA-BREEZES, MOUNTAIN AIR. AND OZONE 



FIFTY years ago people were very fond of talking 

 about "ozone," and the word is popularly used 

 nowadays to signify a mysterious attribute of the air of 

 the sea-coast or moorland without its real significance 

 being generally understood. When Sir Oliver Lodge the 

 other day warned people against hurting their nasal 

 passages by sniffing up an unduly strong dose of ozone 

 produced by a special ozone-making apparatus, I am 

 inclined to think that most people who read what he said 

 wondered what " ozone " might be. 



In the eighteenth century it was noticed that the 

 sparks from a frictional electrical machine are accompanied 

 by a peculiar pungent smell in the air. Many years after 

 that, namely in 1840, the great chemical experimenter, 

 Schonbein, the friend and correspondent of Faraday and 

 discoverer of gun-cotton, found that the smell in question 

 is produced by a special gas, which is formed in the air 

 when electric discharges take place. He found that this 

 gas was a powerful oxydiser would, in fact, oxydise 

 iodide of potassium so as to set free iodine and thus its 

 presence could be detected by means of paper slips 

 coated with a mixture of starch and iodide of potassium. 

 When they were exposed in air which contained even 



minute traces of this strange gas they became purple-blue, 

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