Floating bubbles

This has to be one of the coolest experiments we've done. Since Jr. Scientist E loves bubbles, I've been trying to find some more bubbly experiments to do with her (although she never gets tired of watching baking sod and vinegar fizz, I sure do). I ran across a cool one where you create carbon dioxide by mixing baking soda and vinegar and then you use bubble mix and blow some bubbles into the container. Since carbon dioxide is heavier than the air inside the bubble mix bubbles, the bubbles go into the container and then come to a rest in mid-air (resting on top of the invisible carbon dioxide). The bubbles will pop if they hit the edge of the container, so you need to do this in a large container with a lot of baking soda and vinegar (ah Costco, the kitchen scientist's best friend). The effect is absolutely jaw dropping and both Jr. scientists A and E loved it.