COHESION FIGURES, 



23 



held by the finger at b, its length may be altered at will, 

 but the contraction of the film will always stretch it so 

 as to form an arc of a circle. If a small loop is made 

 at the end of the thread, fig. 26, C, D, the latter fixed 

 at a, and the film broken at b, the thread of the loop 

 will form a complete circle within the ring. 



Very beautiful cohesion figures may be 

 formed if small wire frames are immersed 

 in soap -water and then withdrawn. A 

 triangular frame, fig. 27, made of six 

 little wire rods, ab, ae, ad, be, cd, and 

 db, provided with a handle ae, exhibits 

 after immersion six thin films which are 

 all directed towards the middle of the 

 frame, where they intersect. 



A frame of twelve equal wires, fig. 28, representing 

 the edges of a cube, produces by immersion a small 



FIG. 27 



(an. proj. ^ real size]. 



FIG. 28 (an. proj. g- real size). 



rectangular film in the middle, which is joined to the 

 edge by twelve plane surfaces. If the frame is now 

 again slightly immersed so that the lower edges, ab, be, 

 cd, da, touch the surface of the liquid, a small bubble 

 is formed which, when the frame is again raised, moves 

 to the middle, taking the shape of a cube with convex 

 faces (fig. 28, C). 



Another series of experiments on cohesion figures may 



