ATMOSPHERIC ELECTRICITY AND OZONE. 463 



Average Quantity of Ozone in the Atmosphere. — The quantity of 

 ozone in the atmosphere is exceedingly minute. The proportion varies 

 with the locality, the season, the hour, etc., as we have already seen, 

 and it also varies with the altitude, for it is with this agent as with 

 electricity — it increases as we rise above the earth. According to 

 Houzeau, air of the country, about six feet above the earth, contains 

 about ^oinro of its weight of ozone, or , ^ of its volume. The 

 quantity is so minute that it may probably be increased several fold 

 without perceptible injury to man or animals. 



Origin of Atmospheric Electricity and Ozone. — The sources of 

 ozone in the atmosphere are almost innumerable. Like atmospheric 

 electricity, it results from a wide variety of countless and ever-chan- 

 ging influences ; it is one of the grand resultants of the ceaseless chem- 

 istry of the earth and sky. The evidence is now pretty clear that one 

 prominent source of atmospheric ozone is in vegetable life. The oxy- 

 gen that plants evolve from their leaves is more or less ozonized. It 

 is claimed that ozone is developed with the perfume of flowers. The 

 most odorous flowers, as the heliotrope, hyacinth, and mignonette, are 

 the most prolific generators of ozone. This ozonic property of flow- 

 ers is most manifest under the direct influence of sunlight. Lavender, 

 fennel, mint, clove, and cherry-laurel, evolve ozone with special abun- 

 dance when exposed to the solar rays. It is believed that the oxida- 

 tion of essential oils, as anise-seed, bergamot, etc., under exposure to 

 the light and air, develops ozone, and that in all flowers the source of 

 the ozone is the essence ; hence it is that the most odorous are the 

 most ozoniferous. 



If we accept these conclusions, we must also concede that the cus- 

 tom, now almost forgotten, among physicians, of providing the han- 

 dles of their canes with vinaigrettes, with the fancy that the fumes 

 would protect them against infectious disease, has a certain scientific 

 basis. The aroma of snuff" is said to develop ozone, and for years 

 snuff* has been regarded as a disinfectant. 



Electricity, as is well understood, is generated by any kind of 

 chemical change or action. Even friction and pressure cause elec- 

 tricity to be evolved, as was shown by Armstrong's experiments with 

 jets of condensed air, liberated under high pressure. It was shown 

 by Faraday that the friction of water dropping against bodies gives 

 rise to electricity, and it is probable that the same effect follows the 

 friction of water against air. 



Volta showed, nearly a century ago, that the spray of a fountain 

 furnishes negative electricity. Trolles, and afterward Humboldt, ob- 

 served that a cascade or water-fall filled the air for some distance with 

 negative electricity, and Bell thinks he has proved that a cascade is 

 negative at the top, and positive at the bottom ; that the positive 

 electricity passes into the earth, leaving the negative in the spray. 



We are then to look for the sources of ozone, as of electricity, in all 



