THE 
NEW PHYTOLOGIST 
Vol. XX, No. 3 
PERMEABILITY 
By WALTER STILES 
CHAPTER III 
SURFACE PHENOMENA 
he most obvious way in which the surface differs from the body 
of a liquid is in its behaviour as a thin stretched skin. This is 
most familiarly exemplified in the behaviour of films of soap solution. 
B 
C 
A 
D 
X 
Fig. 1. 
For instance if the rectangle enclosed by the wire frame ABCD 
(fig. i) is occupied by a thin film of soap solution terminated at 
its lower edge by the wire AD which can move freely along the 
vertical wires AB and DC, the film will tend to contract and it is 
Phyt. xx in. 3 
August 19,1921 
