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which exist in the upper regions of the atmosphere. 
In the Lake district the manifestations of ozone are 
considerable ; again there are conditions somewhat similar 
to those already named. 
. On land the amount of ozone generated will vary 
considerably with the character of the surface of the earth. 
In localities where vegetation abounds ozone should exist 
in considerable quantity ; there is the mechanical action of 
the air over the moist surfaces of the vegetation, and the 
formation of aqueous vapour ; and if it be true, as stated, 
that the oxygen which is evolved by plants is in an ozonised 
condition, we should have an additional source for the 
production of this purifying agent. 
Heavy storms of rain, hail, and snow are always accom- 
panied by free electricity and a manifestation of ozone. 
The pleasant sensations experienced on breathing the 
atmosphere after heavy rain are, perhaps, not altogether 
due to the washing of the atmosphere, but in part produced 
by the ozone contained in it. Mr. Baxendell noticed that 
when the fountains at the Waterworks, Arnfield, were set 
in operation he found the manifestation of ozone greater 
than he had observed in severe thunderstorms. This I can 
quite imagine possible. In discharges of lightning the 
production of ozone would be confined to the locality of the 
flash, and the effect on the test paper would depend on its 
situation and the direction of the wind. A water fountain 
may be regarded as a hydro-electric machine,* the friction 
of the water issuing through the jets developing electrical 
action, materially assisted by the conversion of the spray 
into aqueous vapour. I would suggest that this fact should 
be prominently brought before municipal bodies, to induce 
them to erect fountains in all available places in large cities 
as sanitary agents. They might prove highly beneficial in 
crowded localities. 
* Humboldt mentions in Cosmos, vol. 1, page 344, “ That the negative 
electricity near high water falls is sufficiently intense to produce an effect on 
a delicate electrometer at a distance of 300 or 400 feet.” 
