A Soap Bubble

The extreme thinness of the bubble is indeed wonderful. It is estiniated that the 'film in some places is only one three-millionths of an inch in thickness. Probably few of us can conceive of such thinnesb. Let me express it in another way. The 01 d and the New Testament contain soma 8,000,000 of letters. Now one three-millionth is such a part of an inch as the first letter of the Bible is a part of the suni of all of its letters. The bubble, however, is not of eqnal thiakness at all points, and it is for this reason that it has the various colors. For instance, wherever the film is orange red it measnres about three-millionths of an inch; where it is blue, eighty one-millionths of an inch, and at a point where lemon yellow is prominent about twenty one-millionths of an inch. Perhaps you wonder why the colors change from one part of the soap bubble to another. This is because the film of the soap bubble evaporates and grows thinner, but unequally so at different portions. A greenish blue with a palé rose red spot near it indicates an extreme thinness, and at such a point the film is ready to give way at the least jar. You will be glad to know the source of the beautif ul colors. Every one is delighted with them, even if not interested by the explanation of their origin. We may say that they come from the light. Light gives color to all objects, but not exactly as it does to the soap bubble. White light from the sun can be broken into the seven colors which we have seen in the rainbow. In that instance the raindrops separate it inte its parts. A glass prism will do the same, as you may prove by looking through a glass pendant from a hanging lamp. When the light reaches the surface of the soap bubble, a part is reflected from it, and we see images on its surface as if it were a curved mirror. Another portion of the light, however, enters the film and is separated so that parts of the seven colors are thrown into the bubble, and we can see them át various portions of the opposite surface. Another part of the light, af ter being broken by the film, is reflected by its inner surface back to our eyes, so that we see colors at the point where the