Hey, whatever floats your boat!

Amazing demonstration at the Physikshow of the University of Bonn!

So, what's going on here? Well, obviously the hexafluoride gas is heavier than air (about 5 times as heavy), so the "ship" floats. Yeah, I got that. But I wanted to read more about it and pass on what I read here. Unfortunately, my searches of the Internet haven't really turned up much of anything.

There's a Wikipedia entry about uranium hexafluoride, which it describes as "a compound used in the uranium enrichment process that produces fuel for nuclear reactors and nuclear weapons. It forms solid grey crystals at standard temperature and pressure (STP), is highly toxic, reacts violently with water and is corrosive to most metals." Presumably that is not what this is!

There's also a Wikipedia entry about sulfur hexafluoride, which presumably is what this is, but it doesn't mention anything about nifty little science fair demonstrations like this one. It does mention that breathing sulfur hexafluoride will make you voice much deeper (the opposite of breathing helium), because the speed of sound is about one-third what it is normally. Neat. Of course, our body requires oxygen, not sulfur hexafluoride, so breathing the latter is not recommended.

If you come across any other nifty science fair demonstrations like this, let me know!