Brownian movement (also referred as Brownian motion), is first observed by Dr. Robert Brown in 1827. It is the irregular, rapid and random motion of microscopic particles suspended in a fluid (liquid or a gas), resulting from the constant collision with molecules of the surrounding (dispersion) medium. In Brownian movement, the colloidal particles having the same kinetic energy as possessed by molecules in dispersion medium but the particle size of colloidal solution is so large. So, their movement of colloidal particles is slower than the molecules of dispersion medium.
· This effect is observed in all type of colloidal suspensions – solid – in- liquid, Liquid – in- liquid, gas-in- liquid, liquid – in – gas.
· In ordinary suspensions, this effect is not observed because the particle mass is so large than the particles of dispersion medium. So, the collision of molecules of the dispersion medium produces little effect on them. This effect offers a visible evidence of the indiscriminate Kinetic motion of molecules in a liquid.