﻿2 Chapman and Burgess, Note on Chlorine. 



tion to this society, if ammonia, or the products of the 

 interaction of ammonia and chlorine, are present in the 

 mixed gases, combination only occurs after the actino- 

 meter has been exposed for some time to light. 

 Experiments have been conducted for the purpose of 

 discovering to which possible chemical compound this 

 effect is immediately due. Direct experiments demon- 

 strated the negative effect of nitrous and nitric acid. 

 Nitrogen chloride would appear to be indicated as the 

 cause by the following experiment. A dilute solution of 

 ammonia was saturated with chlorine, and divided into 

 two portions. Five c.c. of the first portion were added to an 

 actinometer containing hydrogen and chlorine, which was 

 then exposed to light. The induction period was long. 

 From the second portion the chlorine was removed as far 

 as possible by exhaustion, and 5 c.c. of the resulting 

 liquid introduced into a similar actinometer. The 

 induction period was very short ; and therefore the 

 compound to which the induction period is immediately 

 due belongs to that class of substances which are volatile, 

 and being only slightly soluble in water, are readily 

 removed by exhaustion. Nitrogen chloride fulfils these 

 conditions. 



In certain cases it was observed that even after the 

 gaseous mixture had been exposed to light, until the rate 

 of combination had reached a maximum, and the acti- 

 nometer had subsequently been allowed to stand for some 

 time in the dark, a second induction period resulted on 

 re-exposure to light. This decay in the activity of the 

 mixture is more noticeable when the actinometer contains 

 water, with the purification of which from organic matter 

 no special care has been taken. The phenomenon does 

 not occur when pure water or a solution of ammonia in 

 pure water is used. It is probably due to the presence of 



