Is the following then a fair world-trawler-list consensus statement (W-T-L
CS) on the subject?

1. Pure water freezes at 32 deg F. at which time the H2Os become locked in
   a crystalline matrix.

This is the basis of the centigrade scale.

2. The presence of dissolved salt, NaCl, depresses the point at which this
   occurs. Higher concentrations of salt lead to lower freezing points.

Seawater and brine solutions freeze at a lower temperature. Thats how you
make ice cream and why the sea doesnt freeze when the ponds do.  Fahrenheit
got it down to 0 degrees with 50% salt.

3. The crystalline matrix itself is solely composed of H2O, the NaCl remains
   dissolved in a brine solution.

Thats why icebergs are fresh water and freezing can produce fresh water
commercially.

4. In the open ocean the brine constituent is in equilibrium with an
   essentially infinite volume and therefore stays constant even as  H2O
   molecules are lost to the crystalline matrix.  The value of  28.6 deg F.at
   35 parts / 1000 saline is obtained under these conditions.

5. In a container, in the freezer, as H2O is lost to the matrix the residual
   water becomes less, the salt concentration therefore increases.  This
   depresses the freezing point below the 28.6 given above.

Respectfully,
hmp

hpollock@massmed.org writes:

I'm surprised that no-one has brought on the subject of freezing
alcohol-water mixtures (i.e. wine). If you substitute the Na-Cl in
the statements above with C2-H5-OH, you get an ever increasing
concentration of alcohol. Easy and cheap way of operating a still in
your freezer.  :-)

Cheers - George