60 THE BEHAVIOUR OF HYDRTODIC ACID IN LIGHT. 



light has been ascertained. It has been shown that hydriodic 

 acid in the presence of oxygen is slowly changed to some- 

 thing else, the colour of the solutio'n due to the liberated iodine 

 ultimately disappearing. This change is greatly accelerated by 

 light. There is good reason to believe that the process of the 

 change is one of oxidation, but all attempts to reduce this oxida- 

 tion compound have failed, and the condition in which the 

 iodine exists still remains unsolved. 



In conclusion, my most hearty thanks are due to Professor 

 Mackay for his valuable criticisms, and the kind interest he has 

 taken in this investigation. 



DALHOUSIE UNIVERSITY, Halifax, N. S. 

 April 2nd, 1908. 



