Surface tension

Here's a little random bit of fun for today: kitchen games with surface tension.

One of the things that changing surface tension does is determine how stable bubbles are. So, let's change the surface tension of boiling water with some common household items.

If you set a pot of water on the stove to boil, the lid will rattle when it gets going, and that's about the extent of it. The bubbles pop quickly and aren't very stable.

If, on the other hand, you set a pot of water with some white rice in it on the stove to boil (and forget to turn it down to low the instant it starts to boil) it'll foam up and boil over and make a great big mess of your stove. If you're one of the other three people left in the world who both cooks rice and hasn't got a rice cooker, you've probably had this happen to you at least once.

A while ago I noticed something interesting: there are certain additives you can put in a pot of white rice that changes the surface tension yet again, so it goes back to not boiling over. My favourite of these additives is ground coriander seed, stirred in while the water is still cold. Also, it makes for some really tasty rice. Garlic powder also helps: while the water still foams, it doesn't grow as tall and boil over as quickly.