IN LIGHT IX THE PRESENCE OF OXYGEN. CRtlGHTON. 51 



From this table it is again seen that the iodine content 

 reaches a maximum very rapidly and then slowly falls off again 

 and linally disappears. During the last two hundred hours the 

 disappearance of the iodine is relatively rapid. In this experi- 

 ment it was found that the disappearance of the iodine was due, 

 in part, at least, to evaporation; accordingly, to see whether 

 evaporation was responsible for the whole chaugej, and at the 

 same time to determine how much light influenced this change 

 of iodine, the following experiment was carried out. 



300 cc. of an acid solution of potassium iodide, such as had 

 been used already, were put in each of two reagent bottles, one 

 amber colour, the other clear; these were closed, and about 

 every twelve hours the air that was over the liquid was passed 

 through U-tnbes containing a solution of potassium hydroxide 

 (s]i. g. 1.27), by means of an aspirator.' 



