In article ,
Ian Stirling wrote:
Gregory L. Hansen wrote:

When I pull the hose from the nitrogen exhaust on my cryostat, chunks of
ice will fall on to the aluminum stand and as they melt they'll move side
to side, sometimes dancing back and forth quite rapidly until they're very
small compared to the puddle they're floating in.

Any ideas why they would dance?

It's probably not just ice, but has oxygen and CO2 in it too.
Not to mention acetylene, and all other sorts of traces.

I wouldn't have thought it would be that cold. This is the boiloff from
the liquid nitrogen, and I just have a long hose attached to it to prevent
water vapor from backstreaming in, and to keep ice from building up at the
outlet -- the hose is long enough that the vapor is too warm to freeze
anything before it reaches the end.

I'm actually kind of disturbed that the LN2 boils off so quickly, I don't
think a good design should do that. But I have what I have.

--
"Let us learn to dream, gentlemen, then perhaps we shall find the
truth... But let us beware of publishing our dreams before they have been
put to the proof by the waking understanding." -- Friedrich August Kekulé