Eighty-five years and eight fallen drops later, this surely is a long-running experiment!
The pitch-drop experiment—really more of a demonstration—began in 1927 when Thomas Parnell, a physics professor at the University of Queensland in Australia, set out to show his students that tar pitch, a derivative of coal so brittle that it can be smashed to pieces with a hammer, is in fact a highly viscous fluid. It flows at room temperature, albeit extremely slowly. Parnell melted the pitch, poured it into a glass funnel, let it cool (for three years), hung the funnel over a beaker, and waited.
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Link : Popular Science – FYI: How Long-Running Is the Longest-Running Lab Experiment?