660 
PROFESSORS A. W. REINOLD AKD A. W. RUCKER 
C/=G (6, 5) with rings of higher orders at the top. 
8= —0-38. 
At 14 m , C/ = G (5, 5) ; the right was colourless, and both had rings at the top. 
§= —0-27. 
Now, remembering that 8=p — X, and that a negative value of 8 therefore means 
that the left film had the larger diameter, this experiment indicates that the passage 
of the current for 10 s only produced a difference in the diameter of the rings which 
3 m afterwards amounted to 00 8 mm., and 8 m afterwards to 0*07 mm., and that the 
film disturbed by the current had the greater surface tension. 
At 15 m the current was sent up the right film for 12 s . The coloured rings dis¬ 
appeared. 
At 19 m the right film was faintly coloured, and 
Q={0-56, YG (4,5)}, 
S=—0-28. 
The disturbance produced by the current was less than before, which is accounted 
for by the fact that the film, though colourless, was really thinner than when it was 
previously applied, and thus, the resistance in circuit being greater, the current was 
weaker. That the film was thinner is proved by the fact that, whereas after the first 
application of the current the right film remained for the most part colourless for eight 
minutes, on the second occasion it showed faint colours after four minutes. This 
observation shows that in a film which is not very thick the current may be passed 
for a few seconds without leaving any trace of its action three minutes afterwards, 
but unfortunately it also proves that such treatment is not sufficient to prevent the 
film from thinning. 
At 20 m the current was sent up the right film for 20 s , and the following measure¬ 
ments were made :— 
At 24 m — 
C r =B (5, 0), C/={l-5&, G (4, 0)}. 
8= -0-90. 
At 29™_ 
C,=G (5, 7), Q={3*06, Y (3, 9)}. 
S=—0-44. 
In this case the longer passage of the current caused a considerable disturbance, the 
effects of which were very marked 9 ra afterwards. The experiment was continued in 
the same way, the measurement showing that a current which produced an appreciable 
retardation in the thinning also produced an appreciable difference in the diameters. 
Seventy one minutes after the beginning the state of things was as follows :— 
C,= {1*06, B (3, 5)}, Q= {11*06, Y (2, 7)}. 
8=—0*77. 
