CHAPTER XXXIX.
825. Why are soap-bubbles round?
Because they are equally pressed upon all parts of their surface by the atmosphere.
826. Why are bubbles elongated when being blown?
Because the unequal pressure of the current of breath by which they are being filled, alters the relative pressure upon the outer surfaces.
827. Why does the bubble close, and become a perfect sphere, when shaken from the pipe?
Because the attraction of cohesion draws the particles of soap together, directly the bubble is set free from the bowl.