OZONE AND ANTOZONE. 177 
.. In judging from the reaction upon iodide of potassium starch paper, ozone is 
always in the free atmosphere in variable, but small, quantity. Such test pa- 
pers are not blued when closed in a bottle, and scarcely so, if at all, in a room. 
By exposure to the external atmosphere the effect upon them is extremely va- 
riable. Sometimes in cities it is imperceptible. According to Osann, the color- 
ation is greater by night than by day, and is more decided towards sunrise, at 
the time when the atmospheric moisture is precipitated. It is greater in winter 
than in summer, stronger with clouded than with clear sky, and is especially 
powerful with snow clouds. Every flake of snow falling upon the test paper 
produces a blue stain. By atmospheric electrical discharges ozone is, as might 
be expected, very prevalent. Schoenbein calls attention to the fact that the 
odor in the neighborhood of places struck by lightning is exactly that of ozone. 
The whole subject of ozone, whether in its physical or physiological rela- 
tions, is intensely interesting, and promises, when understood, to be the means 
of solving many problems in the sciences now so ditheult to be comprehended. 
No field of research appears to promise so rich a harvest to the skilled and 
patient observer. 
12s 
