Universal things on Instagram: "The science behind why mercury is banned on airplanes comes down to its destructive reaction with aluminum, the main metal used in aircraft. Aluminum normally protects itself with a thin, invisible oxide layer that stops it from reacting with most substances, even liquid mercury. If mercury manages to touch exposed aluminum, such as at a scratch or damaged spot, it seeps in and forms an amalgam, which is a weak mixture of mercury and aluminum. This amalgam breaks