On 2010-12-23, Phil Kangas wrote:
Here's the answer I received from a retired
material science guy.
phil k.


Hi Phil,

A few comments to get you started. You probably
have a Chemistry textbook to consult to add some
details.

Most metals are soluble in mercury and the alloys
they form are call amalgams. Dentists use amalgam
filling materials, which are alloys usually
containing silver, tin and copper that have been
amalgamated with mercury. Aluminum also forms an
amalgam, that is an alloy formed on contact which
is aluminum dissolved in mercury.

As you know, aluminum readily forms a thin oxide
layer at surfaces in air, which is then very
protective against many environments including
air. In this case, there was likely a scratch or
other defect in the oxide layer that allowed
contact between the mercury and aluminum leading
to amalgamation. Amalgamation of this type has
often been cited as possible means of aircraft
sabotage during WW II.

Beyond formation of the mercury-aluminum alloy in
the reaction shown in the video, one could surmise
that because aluminum is a reactive element, the
apparent gas evolution could result if there was
some water present that would permit the aluminum
in the amalgam to oxidize and hydrogen gas to form
as part of the reaction to form aluminum hydroxide
or aluminum oxide.

Hope this helps.

Merry Christmas,
Don




Also check this out :

http://en.wikipedia.org/wiki/Aluminium_amalgam