Neil Shurley, age 9, of Des .Mioines, Iowa, for his' question:

Why can't we, see evaporated water?

When the kettle boils, a plume of frothy white steam puffs out of the spout. You can see it, but if you poke a finger into it, the cloudy white steam scalds the skin and makesa painful burn. We know that boil¬ing water evaporates and disappears. Some people think it turns to steam, but this is only the first part of the story. when the evaporation job is finished, the wet water has turned into invisible vapor.

Water is made of tiny particles called molecules. They are much too small to be seen one by one. But we can see a drop of wet water because it is made of zillions of these tiny molecules, all crowded together. The wet water can get hot enough to evaporate on a stove or outside under the warm sun. %ben this happens, its tiny molecules separate and leave home. Then we cannot see them because one by one they are too small. Actually they become water vapor, which is an invisible gas. When water evaporates, the vapor floats away and mingles with the other invisible gases of the air.