Calibrating temperature probes

Casey Wilson wrote:

For the boiling point, stick
the probe in a pot of boiling water and it should read 100 degrees. Except,
of course, for the barometric pressure. We all know water boils at lower and
lower temperatures (?? 3 degrees per 1,000 feet??) as altitude is increased.

Question: Why doesn't the same pressure effect occur for the freezing
point?

It does. It's just that the melting point curve is a lot steeper than
the boiling point curve,
so it takes a lot more pressure for the same effect.

An interesting experiment can demonstrate the effect. Suspend an ice
cub between
two supports. Loop a fine wire over the ice cube, and use it to suspend
some significant
weight (say 0.5-1 pounds). After some time the wire will be in the
middle of the ice
cube, with ice above and below it. After even more time, the wire will
"cut" through
the cube and fall out the bottem, leaving behind a solid block of ice.
(The pressure
of the wire on the ice raises the melting point, so that the ice in
immediate contact
with the wire becomes liquid. After the wire passes that spot, the
melting point
returns to normal and the water re-freezes.

Rich Lemert