The pitch drop experiment is an experiment that has been going on for the last 91 years, beginning in 1930. This is the longest lab experiment in history.
The experiment was started to measure the fluidity and high viscosity of a derivative of tar, one of the thickest liquids in the world.
The experiment was started in 1927 by Professor Thomas Parnell of the University of Queensland in Brisbane, Australia. He started this experiment to prove to his students that some substances that look solid are actually very viscose liquids.
Parnell poured the heated sample into a sealed funnel and allowed that sample to remain in the set for three years. In 1930, the seal on Funnel’s neck was removed and the fluid began to flow. It took about 8 years for the first drop to fall.
The ninth drop fell in April 2014. From this it was found that the viscosity of that sample is about 230 billion times that of water.
To watch this experiment live: http://thetenthwatch.com/