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It took 69 years, but at last we've seen the pitch drop. One of the world's longest-running experiments climaxed last week, when a finger-sized bulb of pitch (bitumen) separated from its parent bulk and dropped into a beaker. For the first time ever, this fleeting event has been recorded on video.

The pitch drop experiment was set up at Trinity College Dublin, Ireland, in 1944. The original version of the experiment, at the University of Queensland in Australia, has been running since 1930, but various glitches have prevented that team from actually seeing a drop separate.

"No one has ever seen a drop fall anywhere in the world," says Trinity's Shane Bergin, whose webcam recorded the event on 11 July. "It's one of the oldest experiments – an oddity, a curiosity."

Pitch shatters if hit with a hammer at room temperature. Physicist Thomas Parnell set up the Queensland experiment to illustrate that, although it appears solid, pitch is actually an incredibly viscous liquid. (Recent experiments showed that the same is true for "Gorilla Glass", used in smartphones and tablet screens.)

In 1927 Parnell heated a blob of pitch and poured it into a glass funnel with a sealed stem. After letting the material settle for three years, Parnell cut the stem to allow the pitch to drip out and fall. Gravity has since drawn out a gloopy drop about once a decade, and a ninth is expected to fall sometime this year. The long-running experiment has since been added to the Guinness Book of World Records and won an IgNobel prize in 2005.

Tyyr wrote:It tickles the conspiracy nut feelings a bit that the last time a drop formed the cameras monitoring it fritzed.