113 
PHYSICAL AND MATHEMATICAL SECTION. 
October 12th, 1875. 
E. W. Binney, F.RS., F.G.S., President of the Section, in 
the chair. 
“ On a Source of Atmospheric Ozone,” by Joseph 
Baxendell, F.K.A.S. 
The source of atmospheric ozone is a subject respecting 
which various opinions have been entertained by chemists 
and meteorologists. According to M. Schonbein, Mr. 
Dancer, M. Houzeau, Professor Boscoe, and others, it is 
due to electrical action. Dr. Daubeny, from a long series 
of experiments, was led to attribute it to the action of sun- 
light on the green leaves of plants. M. Gorup-Besanez 
believes it is simply the result of evaporation; and Mr. 
Mackereth regards it as being dependent on a peculiar and 
direct action of the sun’s light upon the oxygen of the 
atmosphere. 
In my paper “ On Observations of Atmospheric Ozone,” 
read October 20th, 1868, 1 stated that from my own obser- 
vations it seemed probable that the amount of ozone near 
the earth’s surface depended upon the height at which 
clouds are formed in the atmosphere. Subsequent obser- 
vations confirmed this view, and also showed that the 
amount of ozone had, in general, some relation to the degree 
of transparency of the lower atmosphere. Thus when fogs 
and haze were prevalent it rarely happened that even the 
faintest trace of the presence of ozone could be obtained ; 
but on their disappearance the indications became more 
marked, and in clear states of the air the test papers were 
generally more or less coloured. It appeared, therefore, 
from these results that atmospheric ozone was absorbed or 
