If you accidentally get soap in the bowl of water, you’ll notice that zillions of bubbles filled with fog will start to emerge from the bowl. This, too, produces a great effect. Place a waterproof flashlight in the bowl along with the dry ice so that the light shines up through the fog. Draw the cloth across the rim to create the soap film lid and, if you are inside, turn off the lights. The crystal bubbles will emit an eerie glow and you’ll be able to see the fog churning inside the transparent bubble walls. When the giant bubble bursts, the cloud falls to the floor, followed by an outburst of ooohs and ahhhs from your audience!
When you drop a piece of dry ice in a bowl of water, the gas that you see is a combination of carbon dioxide and water vapor. So, the gas that you see is actually a cloud of tiny water droplets. The thin layer of soap film stretched across the rim of the bowl traps the expanding cloud to create a giant bubble. When the water gets colder than 50°F, the dry ice stops making fog, but continues to sublimate and bubble. Just replace the cold water with warm water and you’re back in business.