Lava Lamps

Lava Lamps are novelty items normally used for decorations. But What are the blobs floating up and down the lamp?? Those blobs are wax.
The lamp contains a halogen lamp that heats a bottle containing water and the wax(usually transparent translucent or opaque) up. Wax is slightly denser than water at room temperature. However, when its heated up, it becomes less dense. This is because wax expends more than water when both are heated. When heated the wax becomes more fluid and its specific gravity increases and the blobs of wax ascend to the top of the device where they cool and then descend. There is a metallic coil of wire at the bottom of the bottle acts as a surface tension to recombine the cooled blobs of wax.

Hazards of the lava lamp:
In 2004, Phillip Quinn, was killed in an attept to heat a lava lamp on his kitchen stove while observing it a few feet away. The heat fro the fire built up pressure in the lamp and it exploded. The glass broke and it was strong enough to pierce through his chest, heart and causing fatal injuries. The circumstances were proved and comfirmed in a popular science series, Mythbusters. The show also noted that even if the glass did not was not iwth lethal velocity during such an attempt, the hot wax would be enough to cause severe burns. They noted that no one should ever heat a lava lamp on a kitchen stove.

Some Videos:(PART 1) http://www.youtube.com/watch?v=W7_dVUx5lZU
(PART 2) http://www.youtube.com/watch?v=azHzE-5cO3A&feature=related