Five minutes of superfluous lava lamp footage. The fixture is about 27 inches tall from top to bottom, with the glass portion extending 14 inches vertically. Inside the glass container is a mix of colored wax and water, which is heated and illuminated from below by a 100W incandescent bulb and a pair of 25W heating elements in the base.
At room temperature the wax is slightly more dense than the water, but when it's heated it expands and becomes more buoyant, causing it to float up toward the top, where it cools and loses its buoyancy. This convection cycle is thought to model the behavior of hot magma beneath the surface of the Earth.
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