Francis Fahey, aged 12, of Renaselaer,~N;Y. for her question:

Why are soapsuds always white?

These days, even soap powders come in pretty colors. Delicate shades of pink, blue and green help make the necessary job of  dishwashing more cheerful, But why aren't the soap bubbles the same pretty colors as the soap? And what happens to the color?

Soap bubbles are made of air and water. Little pockets of air get trapped in films of water. soap, water and air react together to form countless foamy bubbles. Most of the foam is air. The foam is white for the same reason that whipped egg white is white. Bubbles of air play tricks with the light to turn colorless water and egg white foamy white.

Look at the water under the foamy froth. Maybe the colored soap has tinted it. But the shade is much paler than the soap. This is because the dye in the soap has a larger volume to color. It is spread thin, so thin that sometimes colored soap does not even tint the water. Certainly there is not enough of it to color the fine, fine film of water around a soap bubble.