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Under conditions that need not be very carefully controlled it is possible to cool water to temperatures as cold as -6C without the water freezing.  If an ice crystal is then introduced into the water, or if the water is given a mechanical shock, it will then freeze, with the freeze front propagating through the water at a speed of a few cm/sec. 

There is a nice video of this [[http://faculty.gg.uwyo.edu/kempema/supercool.html|here]].

The heat capacity of supercooled water in this temperature range ought not be far from 1 cal/gm/C, while the heat of fusion of ice ought not be far from 80 cal/gm/C.  This implies that only a small fraction of the water should freeze.

The first experiment would be to verify this, perhaps by sawing the ice that results in half, and looking at it under a magnifying glass or microscope.  One expects to find ice with considerable structural integrity, yet consisting mostly of water-filled voids.  

Other experiments might be suggested by the first.  If the ice turns out to be solid through and though, we would certainly have a calorimetric challenge. 

If interested in this project, talk to Jim Reardon.