From: Paul Doherty (pauld@exploratorium.edu)
Date: Tue Nov 14 2000 - 17:12:26 PST
Message-Id: <l031107e6b63791954709@[192.174.2.173]> Date: Tue, 14 Nov 2000 17:12:26 -0800 From: Paul Doherty <pauld@exploratorium.edu> Subject: Re: pinhole questions about glowing pickles
Hi Regan
We cut a pickle in half the long way and laid nails on the pickle.
The water in the pickle boiled away fastest near the nails where it was
hottest (The concentration of electric current is greatest near the nails.)
We noticed that at random one end of the pickle would dry out a space
around the nail sooner than the other end. As soon as a dry space
surrounded the nail electric sparks would jump across the gap from nail to
pickle through the sodium vapor rich space giving out the sodium vapor
yellow light. Once the sparks start they assure that the water vapor will
evaporate more from that end and actually decrease the current through the
pickle reducing the vaporization at the other end. So once the glow starts
at one end it stays at that end.
I've never seen the glow change ends.
Paul Orth's student soaked pickles in brines including magnesium, and other
salts and changed the color of the glow.
I don't know what the black is, I guess it's rich in carbon from the pickle.
The inside of the pickle vaporizes water so it is at least 100C
The build up of vapor from the boiling water could push the nails out, it
depends on how hard they are held in place.
What did your students observe?
Paul D
Paul "But it is more complicated than that!" Doherty,
Senior Staff Scientist, The Exploratorium.
pauld@exploratorium.edu, www.exo.net/~pauld
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