Wizened, as in When my children bring balloons home from parties, the ones that are filled with helium are often small and wizened by the following morning. And why is helium so transient?

...This leads to a truly bizarre effect if the balloon is filled with the gas sulphur hexafluoride, which has large, very heavy molecules which hardly diffuse through the rubber at all, and so cannot get out. But once again, as in the helium example, there are more air molecules outside than in, so air diffuses inwards and the balloon slowly increases in size.

While we're linking away to Q&A's here's one that explains why radio announcers drink.

• info
  • comment?
  • permanent link
  • email this