121 
with the potash, will form the colourless iodate of potash. 
But it may also be that the direct action of ozone on 
iodide of potassium is retarded or altogether prevented by 
an excess of moisture when the ozone is present in only 
small quantities as is usually the case in the atmosphere, 
and this view is supported by the fact that dry papers 
appear to be generally more sensitive than damp ones. 
Admitting that the inference I have drawn from the facts 
given in this paper is correct, it will enable us to explain 
why, on the sea coast, winds from the sea bring more ozone 
than those from the land, and why, when the cloud 
stratum is high, the quantity of free ozone near the surface 
of the earth is, in general, greater than when the cloud 
level is low. It also indicates that the sudden and con-= 
siderable manifestations of ozone which sometimes occur 
may be found to be due to descending currents bringing air 
from the cloud region to lower and warmer levels and thus 
causing the rapid evaporation of the condensed vapour 
which it contains. It may also enable us to trace out the 
causes of the differences which exist between the mean 
amounts of ozone in different localities, and will, I believe, 
be useful in suggesting new methods of treating meteorolo- 
gical observations and attempting the solution of some of 
the difficult but intere'sting problems which are at present 
engaging the attention of meteorologists. 
February 29th, 1870, 
E. W. Binney, F.R.S., F.G.S., President of the Section, in 
the chair. 
“ An Account of some early Experiments with Ozone, and 
remarks upon its Electrical Origin,’' by J. B. Dancer, 
F.RA.S. 
