this message typed:
2 7 2006 2:51am ET

Holy Moly.

I am currently at work.

Do you know what heat packs are?
Here is a some info from wikipedia.com to fill you in.
source link:
http://en.wikipedia.org/wiki/Heating_pad

A sodium acetate heat pad contains a supersaturated solution of
sodium acetate (CH₃COONa) that heats when you start the
crystallisation process by clicking the piece of metal that is in the liquid.

Because the liquid is supersaturated, i.e. the temperature of the solution is below its

crystallisation point, clicking makes it crystallise suddenly thereby releasing the energy of the crystal lattice. See
sodium acetate for a more technical discussion.

The heat required for crystallisation is retained when the
temperature drops and the solution becomes supersaturated. The heat is
released on solidification, which is triggered by flexing a (patented

[1]) small flat disc of notched ferrous metal which releases very tiny adhered crystals of sodium acetate

[2] into the solution which then act as nucleation sites for the recrystallization of the remainder of the salt solution.

Okay..
For the past few nights I have been putting a unopened soda in a
plastic bottle in the top rack of the freezer beside the ice tray.
Normally I come to claim it an hour or 2 later and it is partially frozen..  It's sort of like an Icee.
Anyway.. Today I left the mountain dew in the freezer for about 3
hours.  When I came to claim it, I thought it was odd,
because the mountain dew was still liquid.
This is where it gets interesting.
When I opened the bottle, the mountain dew started crystallizing from the mouth of the bottle downwards.
It continued crystallizing downwards.
It seemed to stop about halfway down, behind the label where I couldn't see.
I shook it a little and the rest very quickly crystallized.
I have never seen this happen other than heat packs.
I wonder what the requirements are for creating an environment where this can occur.