The folks at Today I Found Out take a look at the Ig Nobel Prize-winning Pitch Drop Experiment:
The 2005 Ig Nobel Prize for Physics was awarded to John Mainstone and the late Thomas Parnell of the University of Queensland, Australia, for patiently conducting an experiment that began in the year 1927 — in which a glob of congealed black tar has been slowly, slowly dripping through a funnel, at a rate of approximately one drop every nine years.
The first epochs of that experiment are documented in the study “The Pitch Drop Experiment,” R. Edgeworth, B.J. Dalton and T. Parnell, European Journal of Physics, 1984, pp. 198-200.