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APPARATUS

Place a thin (~1/2 cm) layer of the oil/powder mixture in a petri dish on the hot plate.  Set the temperature to about 150 degrees.  Convection cells will form and are made visible by the iridescent pigment.  Hot oil rises in the centers of the cells and the cooled oil falls near the cell boundaries.

The cells tend to merge into bigger cells over time.  If desired, you can restore the smaller cells by stirring the solution.

The pattern resembles solar convection cells.  See, for instance, http://www.nasa.gov/mission_pages/solar-b/solar_013.html or solar_022.html.

Set-up: