Wednesday, September 06, 2006

Thermite ahoy!

A man in Doncaster gets caught speeding in the firm's van. Fearing for his livelihood, he decides to eliminate all traces - including the camera. Fortunately for him, he's a railway welder and has access to thermite. Ah, thermite..

I remember this as the coolest reaction going in school science. For the un-initiated, the thermite reaction involves a mixture of powdered aluminium and powdered iron oxide. The aluminium is a reducing agent - that is, it's desperate to get oxidised - and the reaction when the oxygen atoms are transferred from the iron to the aluminium is strongly exothermic. That is, it liberates lots of heat.

The result is satisfying in the extreme. You need some heat - a fuse, say - to get it going, but then it goes as the spirit takes it. We're looking at clouds of brown smoke, blinding white light created by the iron reaching white heat, and sparks. Lots of sparks. And molten iron. The molten iron is the point, commercially - so the reaction is used to weld rails together. A lump of it will melt through most metal objects.

He dosed the camera with the stuff and struck a match. Sadly, the thermite didn't melt into the hard disk drive in the thing, and he was caught because it filmed him driving up to it. If it had been a traditional Gatso camera, the photographic film would probably have caught fire.

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