"Children's children are the crown of old men; and the glory of children are their fathers."—Proverbs xvii.
Fig. 29.—BLOWING SOAP BUBBLES.
828. Why do bubbles, blown in the sunshine, change their colours?
Because the films of the bubbles constantly change in thickness, through the atoms from the upper part descending towards the bottom, and therefore the varying thickness of film refracts, in different degrees, the rays of light.
Because the atoms that compose their films fall towards the earth by gravitation; the upper portion of the bubbles then becomes very thin, and as the denser air of the atmosphere presses towards the warm breath within the bubble, it bursts the film.