Flour Go Boom - Years ago I read about an experiment to demonstrate the effect variable surface area has on combustibility. It involved a metal can, some flour, a candle flame and a long tube. The idea is to simulate a carburator, but with flour instead of gasoline.

Particulate matter can become very dangerous when mixed with air in the right ratio. All those little surfaces have ready access ot oxygen, making a raction happen quickly and with considerable force. This is what makes an empty grain silo so dangerous.

So I finally got the motivation to look for some online references to this phenomenon, and I found one or two.

And then there was this article which contains references to the belief that explosive particulate matter may have been responsible for the Great Fire of London.

Ed tells me that he saw this experiment in high school, but with a paint can. The lid of the can shot up to considerable height. You can bet I'm going to try this.