1109 
them. One of them was exposed to bright sunlight on clear days at 
12 in the noon, the other covered with a piece of black flannel and 
was placed by the side of the other. After one bour’s exposure the 
amount of residual iodine was titrated against standard thiosulphate. 
In the four following observations, in order to exclude air a 
current of nitrogen was passed through the solution and the bottles 
were stoppered and exposed at 12 in the noon as usual. 
" | Light 60’ 0.0635 0.00012 
| Darkness 60’ Do 0.05180 
_ {Light 60’ Do 0.00011 
2 oe 60’ Do 0.05176 
5 | Light 60’ Do 0.00010 
| Darkness | 60’ Do 0.05177 
Light | 60’ Do 0.00012 
2 Darkness | 60’ Do | 0.05178 
In the four following observations a current of carbon dioxide 
was passed through the mixture and thereby oxygen was excluded 
and the effect of carbon dioxide could be observed. 
| Light 60’ 0.0635 0.00011 
| Darkness | 60’ 0.0635 0.05176 
55 | Light 60’ Do | 0.00012 
Darkness 60’ Do | 0.05175 
Light ja RGO Do 0.00010 
ke | Darkness 60’ | Do | 0.05180 
Light 60’ Do 0.00012 
2 | Darkness | 60’ Do | 0.05178 
Evidently oxygen and carbon dioxide are without any influence 
on the actinometer. 
Now the effect of diffused day-light was observed. The bottles 
were put in a shady place on bright sunny days. 
