Pitch - world's most viscous liquid | Pitch drop experiment

Pitch, a highly viscous material derived from tar which behaves as a very slow flowing fluid at room temperature.

The viscosity of pitch is about 230 billion times that of water.

At a first glance, pitch looks like brittle solid which can be shattered by hammer but as a matter of fact, it is a very thick fluid even at room temperature.

In 1927, Professor Thomas Parnell of university of Queensland in Australia, started an experiment to illustrate the liquidity of pitch.

He took a sample of heated pitch and poured in to a sealed funnel and allowed it to settle for 3 years. Then in 1930, the seal from funnel was taken off and pitch was allowed to flow. A transparent bell jar covers the funnel and beaker.

The first drop fell after 8 years in December 1938. And till today, only 9 drops have fallen. The last and 9th drop fell in April 2014. The next drop is expected to fall sometime in next decade.

Initially, the experiment was not conducted under any special controlled atmospheric condition but in 1988, the air conditioning was added at the place of experiment.

Thomas Parnell passed away on 1 September 1948 without seeing a live drop fall.

After that, Professor John Mainstone came in charge. He look out the experiment for about 52 years and passed away on 23 August 2013 without seeing a drop fell.

No one ever watched a drop fall live. In 1988, professor John was very close to watch the drop fall but while he went out to take a cup of coffee and returned back, the drop was fallen. Hard luck!

After that, the cameras were installed and the 9th drop was recorded.

Currently, Professor Andrew White is in command of the experiment.

The funnel still have enough pitch that it will run at least next 100 years. Also this experiment is noted in Guinness world record as world's longest running laboratory experiment.

To watch the experiment live, go to www.thetenthwatch.com.