The electric flour voltage test

Granular materials give off a zap just before slipping

Ordinary baking flour isn’t the most electrifying substance, but spilling a box of the stuff yields a jolt of voltage that has scientists excited about their prospects for sensing catastrophic events like earthquakes and industrial accidents.

As a crack opens in a powder bed, the voltage between the fissure and a spot 1 centimeter away suddenly drops, scientists have found.