AND CHLORINE UNDER THE INFLUENCE OF LIGHT. 
87 
upwards. Single sparks were obtained by working the contact breaker with the 
hand. The result obtained, from a large number of experiments, was that, however 
quickly illumination takes place, an expansion is always followed by a contraction. 
showing the formation of hydrochloric acid. For the smaller contractions noted the 
index was carefully watched with a lens to detect the small contraction. 
The following table shows the results of some experiments, illumination being by a 
single spark :— 
40 
35 
30 
25 
SO 
15 
10 
5 
0 
