Ralph Geraci, age 9, of Utica, N.Y., for his question:

WHY DO RAPIDS MAKE THE WATER WHITE?

When you mix soap in the bathtub, it makes a frothy white foam because the lather is made of tiny bubbles filled with air. The special mixture of air and water looks white. A mixture of air and mini droplets of moisture also looks white. This is why white is the color of morning mists and many clouds. Rapids also are a mixture of air and water.

    Naturally, a running river does not use soap to whip up a frothy white lather. As it dashes over the rocks, the splashing water breaks into drops that mix with the air. Some form bubbles that look like soapy white foam. Some form mini¬ droplets that look like a misty white fog.