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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@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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