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enthusiast
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enthusiast
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My response, to Angel's Shakespeare-quote above, seems to fit better under the thread on "windy expostulations".
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Carpal Tunnel
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Carpal Tunnel
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If it's zero degrees outside today and it's supposed to
be twice as cold tomorrow, how cold is it going to be?
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Joined: Jan 2001
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Carpal Tunnel
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Carpal Tunnel
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Zero degrees with a strong wind is twice as cold. I'm reminded of a story I read in Chemistry book a long time. Somebody persuaded the Czar of Russia to have all the Army's buttons made of pure tin. There is one problem though, which was not known to the button makers. I think it is at forty below zero Centigrade (which happens to be same as forty below Fahrenheit), pure metallic tin becomes a powder!
which to me evokes a ludicrous visual image of a long column of half frozen Russkies having to hold up their trousers with both hands.
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Joined: Apr 2002
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enthusiast
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enthusiast
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I think it is at forty below zero Centigrade (which happens to be same as forty below Fahrenheit), pure metallic tin becomes a powder!As I recall, the pipes of the church organ in the great cathedral of St. Petersburg, being made of tin (as was the then-practice), collapsed completely during a cold snap. Edit: "A cathedral in St. Petersburg (now Leningrad) installed a magnificant organ with tin pipes. Came a cold, cold winter and the pipes disintegrated--which is how chemists learned about white tin and gray tin. Ordinary metallic 'white tin' is stable only at relatively warm temperatures. In winter cold, there is a tendency for it to turn into a crumbly nonmetallic 'gray tin.'" Isaac Asimov's Book of Facts, p. 246) http://www.joesabah.com/dseibert/021.htm; near the bottom
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Carpal Tunnel
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Carpal Tunnel
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Dear Bean: I am going bananas trying to remember term for an element changing characteristics in this way.
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enthusiast
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enthusiast
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bill, polymorphous (in the chemical sense) is not quite right, but perhars may trigger some memories. Edit: pleomorphism may be synonymous. Edit: The forms are called allotropes and the transformation is called a reconstructive transformation. For tin, the equilibrium termperature for the transformation is (at normal atmosphreric pressure) 13.2 degrees C. http://www.msm.cam.ac.uk/Teaching/pastpapers/1998-IA.pdf, at bottom of page 5
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Carpal Tunnel
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Carpal Tunnel
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Polymorphism seems an acceptable description, but I am sure there is another special term. And I actually think it was at minus fourteen degrees that the transition in tin takes place. It was over sixty years ago that I read it, and no refreshment since. Dear Bean, where are you when we need you?
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old hand
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old hand
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I know what you mean, Dr. Bill, I think there is a specific word for a sudden change of state like that - the crystal lattice must suddenly re-arrange into a state with lower energy. Crystallization is the closest I can think of but it's not the one I'm looking for. Let me ponder on it - I don't have any solid state physics books around me right now.
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Joined: Jan 2001
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Carpal Tunnel
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Carpal Tunnel
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Dear Bean: I found a chemistry glossary that had "allotrope" which seems close but not word I knew:
allotrope. allotropy; allotropic; allotropism. Compare with isotope and polymorph.
Some elements occur in several distinct forms called allotropes. Allotropes have different
chemical and physical properties. For example, graphite and diamond are allotropes of
carbon.
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enthusiast
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enthusiast
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Bill, see my edits above, with links, made about 80 minutes ago. I guess I should have put them in separate posts, but I didn't want to overpost!
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