﻿Ultra-violet Light on Chlorine. 



765 



Influence of a Trace of Carbon Disulphide. 



It was found that when the proportion of chlorine was 

 increased beyond about 1 per cent, the number of positive ions 

 began to decrease. It was considered possible that this 

 might be due to increase in the rapidity of recombination 

 accompanying increase in concentration, and accordingly a 

 series of experiments was conducted in which a truce of 

 carbon disulphide was allowed to diffuse into the air con- 

 taining chlorine, for Lenard had found that this substance, 

 under the influence of ultra-violet light, furnished nuclei 

 capable of conserving the ions. 



With air containing only a trace of carbon bisulphide the 

 number of ions produced was only slightly greater than when 

 pure air was employed, but immediately chlorine was added 

 the effect was very marked, a decided increase taking place 

 in the number of positive ions formed. 



Curve 11. — Shows a typical example of the results obtained 

 for positive ions in this series of experiments. It will be 



Curve II. 



+ /OA/S 



Dry c7/r <?/ i/e/ocfYj/ ?■$ //tres per rn/mfe 

 + 0-3 % C/t/orfnc 



trace CS g 



so 



100 VOLTS 



Condenser Potential 

 Mobility of + ions. 

 noticed that the curve begins to run horizontally at about 

 30 volts, signifying that much larger ions are present than 

 in Curve L, moving with less than one tenth the speed. 



