22 



EXPERIMENTS ON LIQUID FILMS. 



the smallest possible area. Some experiments on liquid 

 films are exceedingly beautiful. A wire ring with a 

 handle is immersed in soap solution contained in a flat 

 saucer, and then withdrawn. A thin even film will be 

 formed within the ring. If this 

 film be gently blown upon, it will 

 become curved, and finally form 

 a little bag, fig. 25, which con- 

 tracts again if the blowing ceases, 

 and assumes its former appear- 

 ance of a plane circular surface. 



But if the handle of the ring, 



. 25 (| real size). 



while the blowing continues, be 

 turned between the fingers, the 



bag will appear to become tied up, will separate 

 itself from the ring and immediately form a beautiful 

 round soap-bubble. If a very fine silk thread, 

 wound from a cocoon, is tied to two points of the 

 fig. 26, A, B, and the film which is 



ring, a and 



o 



o 



Fro. 2G (l real size}. 



formed be broken within the portion c by the finger or 

 a rolled piece of blotting-paper, the unbroken portion 

 of the film will contract and stretch the thread into a 

 beautiful curve. If the thread be fixed only at a and 



