"jim rozen" wrote in message
...
The original question I think was looking for a very basic
intuitive answer. I didn't reply because I thought he did
not want to hear about phase diagrams, etc.

Also because it was a 'why' question and I'm not very good
at those - better at "how" questions.

Yeah, amazing how such simple questions about things some of us encounter
every day have such complicated and deep answers. Just the kind of thing
Richard Feynman loved, I'm sure.

Tim

P.S. Thanks for the kudos Ed and BS... it's amazing what you can find on the
internet!

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"California is the breakfast state: fruits, nuts and flakes."
Website: http://webpages.charter.net/dawill/tmoranwms