AND CHLORINE UNDER THE INFLUENCE OF LIGHT. 
97 
intensity was different for the four series of experiments, but the same through each 
series. The insolation vessels also were not all the same, so that the curves are not 
comparable except in each sejjarate series. In fig. 12 the curve representing the 
experiment with fresh gas is not plotted, as the inert period in this case was about 
Fig. 12. Abscissse, time in minutes from beginning of illumination. 
Ordinates, HCl formed. 
Curve I, 1 hour dark. Curve H, 15 minutes dark. Curve HI, 10 minutes dark. 
Curve IV, 5 minutes dark. Curve V, 1 minute dark. 
90 minutes, and hence the curve could not be placed on the same diagram as the 
others of the same series without crowding unduly the other curves. 
With the same insolation vessel, and different intensities of light, the maximum 
action is proportional to the intensity of the light. (See Buxsen and Boscoe, 
‘ Photochemical Besearches,’ Part II., p. 387.) Bunsen and Boscoe also showed 
that the time of exposure necessary to effect the first combination decreases with 
VOL. ccii.—A. 
o 
