TEXT BOOK OF PHYSICAL PHARMACEUTICS-II

The colloidal state was first recognized by Thomas Graham in 1861. He introduced most of the terms still used in describing a colloidal system. The word colloid is derived from Greek : kolla means glue and eidos means shape. The fundamental characteristic of colloidal system is dispersity. A colloidal dispersion has traditionally been defined as a suspension of small particles in a continuous medium (generally liquid). Also a colloidal state is treated as an intermediate between true solution and suspension. The modem colloid science deals with coarsely dispersed systems (suspensions emulsions powders etc.) with a particle size exceeding 103 nm and highly dispersed or colloidal systems with a size below 103 nm specifically from 103 to 1 nm. So the particle sizes of colloidal dispersion fall in the range of 1-103 nm.