Mecury in a Sealed Flask

[kdb003]

My chemistry class has a beaker with liquid mercury in a sealed beaker with a some purple/blue crystals in it. It also looks as if there is some sort of gas in the beaker. There is no way to run electricity through the beaker.
Does anyone know what this is or what it is used for?

[thunderfvck]

Mercury is opaque, how can you see what's inside of it?

Maybe it's iodine dissolved in some water, and it's saturated to it doesn't all dissolve. That IS if iodine is soluble in water, but you get the idea...