Watch how sediments settle much faster in an angled container

This great demonstration of the Boycott effect, where "the rate at which solid particles sediment under the action of gravity can be greatly enhanced if the walls of the settling vessel are inclined rather than vertical." Discovered by Arthur Edwin Boycott in 1920, the effect is caused by convection and has important uses in everything from plasma processing to sewage treatment.

Image: YouTube / Fluid Dynamics