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From: jlg@lanl.ARPA
Newsgroups: net.sci
Subject: Re: Interesting seminar
Message-ID: <23051@lanl.ARPA>
Date: Fri, 8-Mar-85 16:49:42 EST
Article-I.D.: lanl.23051
Posted: Fri Mar  8 16:49:42 1985
Date-Received: Mon, 11-Mar-85 05:37:38 EST
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Organization: Los Alamos National Laboratory
Lines: 23

> > THINGS we learned was how to walk on 1600-2000 degree (F) HOT coals IN OUR 
> > BARE FEET!  The POSSIBILITIES and OPTIONS that this one act releases in an 
> > individual are absolutely awesome!  To put the POWER and WORTH of this 
> 
> Wow, I can't think of how many times I've needed to walk on hot coals!  :-)
> There is a short article in the March issue of Science 85 on how fire-walking
> works, prompted by this fad.  Essentially, there are a few physical reasons
> why: coals have a very low specific heat and are very poor conductors of
> heat, and moisture in the skin vaporizes which provides an insulating layer
> of steam and dry skin which also conducts heat poorly.  It was pointed out
> that a real test of mental powers would be to walk across aluminum heated
> as hot.


Not at all.  The same boundary layer occurs.  The Scientific American
article some years back recommended heating the backs of shovels for this
experiment.  The author of the article had walked across 12 (I think)
shovels heated to 1500 degrees F.  Be careful if you try this though, the
boundary layer is not properly effective at LOWER temperatures (<1100
degrees).  At higher temperatures, the boundary layer is not effective
either, but you'll melt your shovels if you go too high anyway.

J. Giles