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    Re: Artificial Horizons and Tea
    From: Trevor Kenchington
    Date: 2003 Jul 11, 21:11 -0300

    Thanks to Phil Guerra for the two Web links.
    
    I guess our childhood playing with liquid mercury wasn't a great idea
    but many of us have done it and few seem to show much in the way of
    symptoms.
    
    Phil's first link led to a page that points out the extreme toxicity of
    methyl mercury (the very nasty organic compounds), the dangers of a
    number of inorganic mercury compounds, and the nasty consequences of
    inhaling gaseous mercury -- such as you might get from heating the
    liquid form. But nothing there suggests significant toxicity from the
    unheated liquid if you were using it in an artificial horizon out of
    doors and didn't stick your face right over the surface.
    
    There is some good advice:
    
    * Do not eat, drink, or smoke; or store food, drinks, smoking materials,
    or cosmetics in areas where mercury is in use.
    
    * Avoid skin and eye contact. Use rubber or plastic gloves when handling
    metallic mercury
    
    * Wash hands and face after handling mercury, before lunch or breaks,
    and at the end of the work day.
    
    * Transfer of liquid mercury between containers should be carried out
    over a tray or pan to confine any spills.
    
    And so on. You would, however, also be well advised to take those same
    precautions if your preference in an artificial horizon is used engine oil.
    
    
    
    Phil's second link also emphasized the dangers of inhaled gaseous
    mercury. It also included two rhetorical questions and an answer: "I
    have mercury amalgams in my dental work.  Am I slowly being poisoned?
    Should I have them removed?     You are not being poisoned.  Elemental
    mercury absorption in the gastrointestinal tract is negligible,
    particularly in the relatively small quantities generated from dental
    amalgams.  For children and women of childbearing age, a physician
    should be consulted."
    
    
    I'm no chemist and I have no medical training, so only a fool would
    follow my guidance on this point. But it looks to me that a mercury
    artificial horizon, handled with reasonable care, is not likely to cause
    you serious harm. If anything, the suggestion of using Scotch in winter
    conditions sounds more risky: It would be a crime to waste even a drop
    but downing the entire contents of a pie plate after each observing
    session could markedly shorten your life -- no matter how pleasant the
    experience!
    
    
    So, to repeat George's question: Is it possible for a member of the
    general public to buy elemental mercury in the quantity needed for an
    artificial horizon?
    
    
    Trevor Kenchington
    
    
    --
    Trevor J. Kenchington PhD                         Gadus{at}iStar.ca
    Gadus Associates,                                 Office(902) 889-9250
    R.R.#1, Musquodoboit Harbour,                     Fax   (902) 889-9251
    Nova Scotia  B0J 2L0, CANADA                      Home  (902) 889-3555
    
                         Science Serving the Fisheries
                          http://home.istar.ca/~gadus
    
    
    

       
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