An emulsion is colloidal dispersion in which both the dispersed phase and the dispersion medium are liquids.
The two well known examples of emulsions are:
1) Milk in which the particles of the liquid fat are dispersed in water.
2) Cod liver oil emulsion in which water is dispersed in the oil.
Method of preparation:
An emulsion is prepared by shaking strongly the mixture of the two liquids or by passing the mixture through a colloid mill known as the homogenizer. The emulsions thus prepared from the pure liquids are usually not stable and the two liquids separate out on standing. To get a stable emulsion, small quantities of certain other substances are added during preparation. The substances thus added to stabilize the emulsions are called emulsifiers or emulsifying agents. The substances commonly used as emulsifying agents are soaps of various kinds, long chain sulphonic acids or lyophilic colloids like proteins, gum, and agar.
