In Print: Lord Kelvin’s Experiments
Aug21

In Print: Lord Kelvin’s Experiments

The Newscripts blog would like to be closer Internet buddies with our glossy print Newscripts column, so here we highlight what's going on in this week’s issue of C&EN. This week's column got started when astute reader Don Borseth wrote in to question something the Newscripts gang had put in a column a few weeks ago—that the famous University of Queensland pitch-drop experiment was the longest-running laboratory experiment. The folks at Guinness World Records seem to think so, but Borseth was dubious. He recalled Lord Kelvin's diffusion experiment at the University of Glasgow from the 19th century. That experiment was set up in 1872, when the pitch-drop's creator Thomas Parnell was no more than a twinkle in his father's eye. If it was still ongoing, wasn't it the elder statesman of experiments? The Newscripts gang loves getting reader mail, particularly when we can get a new column out of it. That Kelvin's experiment is at the University of Glasgow was icing on the cake for this reporter since my husband is an alum from the school's chemistry department (Go Glasgow!). I wondered if my husband had even seen Kelvin's experiment, maybe visited it as part of his studies. As it turns out, he had never even heard of it. And so the hunt was on. I got in touch with a Lee Cronin, a Glasgow chemistry professor I met years ago at a meeting in Portugal, to see if he knew anything about Kelvin's experiment. Indeed, Cronin told me, when the pitch-drop was making headlines in July he was also doubtful of its claim to be the longest-running laboratory experiment. But the internet offered little in the way of evidence of Kelvin's diffusion setup. All I could find was this brochure on this history of the room that houses the experiment. I sought out David Lindley, author of the Kelvin biography "Degrees Kelvin: A Tale of Genius, Invention, and Tragedy" to see what he could tell me about Kelvin's work in this area. "I have to confess I don't know about the diffusion experiment you mention," he wrote to me. But coincidentally, he said, the news of the pitch-drop had got him thinking about Kelvin. "I read in several places about the Australian pitch-drop experiment, and it reminded me of one of Kelvin's lecture demonstrations, in which he would put some metal bullets on top of a slab of some sort of pitch, and corks below—after a time, supposedly, the bullets drop through and the corks bob up. My understanding is that he liked to do this as a demonstration for students, so I suppose he must have used a fairly soft...

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In Print: Pitch Drop Experiment Tests Our Patience
Aug02

In Print: Pitch Drop Experiment Tests Our Patience

The Newscripts blog would like to be closer Internet buddies with our glossy print Newscripts column, so here we highlight what’s going on in the current issue of C&EN. They say that good things come to those who wait. This is not true for John S. Mainstone. For 52 years, the University of Queensland, Australia, professor has been hoping to one day see a drop of pitch, which is a derivative of tar, fall to Earth. And for 52 years, Mainstone has been fruitless in his efforts. All that, however, may soon change. As C&EN associate editor Emily Bones writes in this week's Newscripts column, Mainstone's pitch drop experiment--in which pitch is monitored as it slowly descends from the top of a glass funnel--will soon result in a drop of pitch actually falling. And to make sure no one, especially Mainstone, misses this magical event, the university has set up a live webcam to monitor the experiment. Because of pitch's viscoelasticity, which results in the material exhibiting both viscous and elastic properties, more than a decade can pass between individual drops, thus makes the impending drop especially exciting. What's more, the impending drop could not come at better time for Mainstone, who is still attending to the salt that was rubbed into his wounds on July 11 when a replica of the pitch drop experiment at Trinity College Dublin actually captured, for the first time ever, a pitch drop on film. This event, recorded by Trinity physicist Shane Bergin and colleagues, can be seen in the video below. “The existence of the Trinity College Dublin pitch drop experiment was certainly a great surprise to me--and apparently even to the locals in Dublin, too," says Mainstone, who tormented himself by watching the replica's video "over and over again" for "many hours." Don't feel too bad for Mainstone, though. As he tells Newscripts, there is definitely room for improving upon Trinity's pitch drop. "It was certainly a disappointment to me that their drop was so large that it 'bottomed' in the apparatus and thus led to the final rupture being generated bilaterally,” he says. Here's hoping that when Mainstone finally does see his pitch drop, it lives up to the expectations that he has been building up for 52 year long...

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