By Sunil Bhardwaj

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Though colloidal dispersions are fairly stable, the particles slowly settle down under the influence of gravity if kept for very long time.

It is a very slow process and is just like the falling of spherical body in a viscous medium.

The colloidal particles get distributed under the gravity, heavy particles at the bottom and light particles at the top.

Such a movement and distribution of colloidal particles under the influence of gravity is called sedimentation.

A potential is developed between the top and the bottom layers.

It can be observed by introducing the suitable electrodes at different levels in the stream of falling colloidal particles.

Such a potential is called sedimentation potential.

Since this effect was first observed by Dorn it is also known as Dorn effect.