﻿Manchester Memoirs, Vol. xlix. (1905), No. 13. 3 



substances, which are attacked by the chlorine in the dark 

 with the production of the compound, which prevents the 

 combination of hydrogen and chlorine in light. In 

 support of this view, it may be mentioned that the phe- 

 nomenon in question was particularly pronounced when a 

 solution oi aniline hydrochloride was used, the second 

 induction period being in this case longer than the first. 



It was at one time thought that sulphur dioxide acted 

 in the same way as ammonia, although in a much less 

 marked degree. Subsequent investigation has shown that 

 this is doubtful, and that the small effect observed was 

 probably due to small quantities of nitrogenous organic 

 matter originally present in the water. This matter is 

 being further investigated. 



