Classification of Colloidal Systems

Thomas Graham referred to colloids as  the study of sub microscope dispersion. According to him, it dealt with the dispersed systems of a definite size. Dispersions are classified on the basis of the size of the particles.

The particles are dispersed through out the solvent in the form of molecules or ions (molecular dispersion) and it is a one phase system with molecules having dimensions below 1 nm.

If the particles range in size from 1 mm to 0.5 mm, they can remain dispersed for a long time without precipitation and constitute a colloidal system.  When the size of the dispersed particles is more than 0.5  mm it is termed coarse dispersion or suspension.