Since I’ve recently been posting about next-generation Boy-Scout equipment, here’s a brilliant little hack that has been making the rounds on blogs: How to light a fire using a Coke can and a chocolate bar.

The bottom of a Coke can has a neatly parabolic shape, which makes it terrific as a reflector; hold it up to the sun, and it can concentrate the rays into a point so tightly focused that it is of ignition intensity. The problem, as the Tracker Trail wilderness-survival blog points out, is that if you look at the bottom of a normal can …

… note the fine straight lines in the aluminum. These scatter the sun’s rays, and prevent them from being focused together into a single bright point. [snip] It needs polishing. The chocolate does an excellent job of this.

Chocolate as a polishing agent? Who knew? Apparently, it only takes about half an hour to achieve a sufficient shine; the astonishing, gleaming results are pictured above. Also check out the way-cool pix on the site to see the reflector in action, igniting some tinder!

This is totally the stuff I would have loved doing back in the Boy Scouts: Using everyday materials — and ingenious applications of science — in the service of burning an entire forest to a charred stump. Indeed, the Boy Scouts always had a hacker vibe: The handbooks were always filled with crazy projects, encouraging you to jerry-rig water filtration systems, long-distance signalling mechanisms, and ham radios. And then there was that excellent Harper’s story about the Boy Scout who built a nuclear reactor in his back yard …

(Thanks to Boing Boing for this one!)