Traditional retro lava lamps are familiar to most people, but try this updated version in your local pub.
- pint of lager (or other fizzy drink)
- nuts (a small handful)
- pint glass
- spoon or other stirrer
- Drink some of the beer so that the glass is approximately 3/4 full.
- Leave the beer for approximately half an hour to reduce the amount of bubbles – it may also be useful to stir the lager a few times.
- Tip in the nuts.
- Watch as the nuts gradually float up to the surface of the liquid, then fall back down again, just like a traditional lava lamp.
How Does it Work?
This effect relies on the gas contained within the fizzy drink. The nuts at the bottom of the drink have imperfect surfaces, where small pockets of air will form. The longer they stay still, the larger the bubbles of air that will accumulate. Eventually the bubbles will be large enough to provide enough buoyancy to counter the weight of the nuts, thereby lifting them off the bottom of the glass. When they get to the top, the bubbles burst, removing the buoyancy from the nuts, causing them to fall back to the bottom of the glass.
Tips for Success
This trick works best if the lager (or other fizzy drink) doesn't have TOO much gas in it. If the nuts all float on the top then there is too much gas. Conversely, if the drink is too flat then they will mostly stay on the bottom – a great excuse to have another beer…
Another pub-oriented trick, but one that will transfer to other venues very easily. If your audience are too young to use beer then substitute any other fizzy drink – light coloured ones are best, so that the audience can see the nuts moving within the liquid. This is a good demonstration to leave on the side for a while, and let your audience notice it while you're performing some of the other demonstrations.
Did You Know?
This demo has been in use for several centuries and was very popular at Versaille where a single raisin would be dropped into a flute of champagne and would then bob up and down all afternoon.