Tim Taylor, age 10, of Morrow, Georgia, for his question:

How do they make carbonated water?

This is the season when warm, thirsty citizens think of pop    fizzy wet pop with busy bubbles and fruity flavors. Some people call the basic ingredient soda water. It is water, pure water, but no soda is added. The bubbles are carbon dioxide gas, squeezed into the water under pressure. So long as the mixture is kept inside a bottle sealed with a tight cap, the carbon dioxide gas stays dissolved in invisible particles. But take off the pressure, uncap the bottle, and the captured gas promptly frees itself in rising bubbles.

Pressure, or weight, forces many gases to dissolve and disappear in water    until the pressure is released. To make carbonated water, a pressure of 5 to 10 atmospheres is exerted. This is a weight of 73 to 147 pounds pressing down on every square inch. However, this pressure is not needed to keep the gas in solution. A light, airtight cap is enough to keep it mixed with the watery ingredients in the bottle.