656 
PROFESSORS A. W. REINOLD AND A. W. RUCKER 
Table V. 
c. 
8 
dT found by measurement of 
(1) Three ordinates. 
(2) One ordinate. 
Per cent. 
Per cent. 
{■2'5 6, G (3, 5)}. 
2-35 
41 
5-2 
{36, Y (2, 6)}. 
2-69 
5 - 5 
6-0 
{86, B(2, 5)}. 
2-42 
4-5 
5-4 
{106, 0 (1, 9), B (2, 5)} . . 
2-53 
5-3 
5-6 
{186, 0(1,9), B (2, 5)} . . 
2-37 
4-3 
5-3 
When both films are flooded, and are therefore presumably in the same state, there 
is, notwithstanding, in general a more or less marked difference between their 
diameters. To this we generally refer as the zero error. 
The following results were obtained under these conditions with six different films:— 
Table VI. 
8 
d T found by measurement of 
(1) Three ordinates. 
(2) One ordinate. 
0-76 
Per cent. 
0-7 
Per cent. 
17 
0-36 
1-0 
0-8 
0-19 
0-8 
0-4 
012 
11 
0-3 
0-43 
-0-4 
1-0 
o-oi 
o-o 
o-o 
Mean 
0-53 
0-70 
Tliesc results do not show such a constant difference between the two methods as 
is exhibited in the previous table, and it is, therefore, probable that when the bulging 
and contraction of the films becomes considerable there is a little slipping. 
Taking, however, the lowest figures, these experiments are, we think, fatal to 
Van dee, Mensbiiugghe’s explanation. He explains similar phenomena by means of 
the general principle: “ Si la couche superficielle d’un liquide augmente, ou qu’elle 
devienne le siege d’une energie potentielle qu’elle ne possedait pas d’abord, il y a 
refroidissement, et la tension est plus grande one primitivement, &c.” # 
From this point of view the surface of the liquid of which the thick film is formed 
is continually being renewed, it is therefore cooled, and the result is due to the 
increase of surface tension which follows. 
* ‘ Bruxelles, Acad. Sci. Mem..’ vol. 43 (No. 4, p, 7). 
