[sci.chem] Mercury and

ornitz@kodak.UUCP (Barry Ornitz) (02/28/90)

In article <1990Feb27.055111.18154@ux1.cso.uiuc.edu> forbes@aries.scs.uiuc.edu 
(Jeff Forbes) writes:
>The mercury cannot amalgamate the aluminum though the oxide coat. Aluminium
>can be amalgamated with certain mercury salts which is useful if you want to
>react the aluminum with something that cannot break through the oxide layer.

Aluminum is fairly easy to amalgamate once you get through the oxide coating
found on any aluminum surface that has been exposed to air.  One simple way
is to place the mercury in the bottom of a small container and cover it with
hydrochloric acid.  Take the aluminum piece to be coated and immerse it in the
acid long enough for the oxide layer to be etched away; then immerse it into
the mercury below.  When the aluminum piece is removed, it should be coated
with a thin layer of mercury.

An interesting effect may be seen with aluminum amalgam.  The aluminum in the
surface of the amalgam will oxidize when exposed to air and slough off, but 
most of the mercury will remain and form new amalgam.  This will continue 
until either the mercury or the aluminum is consumed.  The aluminum oxide
formed will be a light, fluffy material.  If a piece of aluminum amalgam is
placed in a spot where air currents are negligible, the oxide can sometimes
form long, delicate "feathers".  It is dangerous to handle these, however,
because of the mercury content.

Remember that while metallic mercury not be very dangerous to handle, mercury
vapor is quite toxic.  The finer the droplets of mercury from a spill are, the
more surface area is exposed for vaporization.  The mercury left in the
"feathers" described above is extremely finely divided and thus quite 
hazardous.  If you spill mercury, dust the area with sulfur before trying to
vacuum it up.

BTW, we have EXTREME restrictions on mercury use at this plant.  Some of our
products go into film manufacturing and mercury is a silver halide poison.
We even restrict some cosmetics on employees that contain mercury compounds.
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|  ___  ________  |       Dr. Barry L. Ornitz          WA4VZQ
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