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Emulsion = colloidal dispersion of one liquid in another immiscible liquid. Two types: O/W (oil-in-water): oil dispersed in water. Dilutable with water. Examples: milk, vanishing cream, mayonnaise. Emulsifiers: soap, proteins, SDS. W/O (water-in-oil): water dispersed in oil. Dilutable with oil. Examples: butter, cold cream, petroleum emulsions. Emulsifiers: long-chain alcohols, calcium stearate. Emulsifier role: adsorbs at oil-water interface, reduces surface tension, prevents coalescence. Distinguishing tests: (1) Dilution with water: O/W stays homogeneous. (2) Dye test: water-soluble dye colours O/W medium. (3) Conductivity: O/W has higher conductivity (water is conducting). Demulsification: breaking the emulsion. Methods: heating, centrifugation, freezing, adding demulsifier (opposite-type emulsifier), electrostatic methods. Applications: emulsions in medicine (cod liver oil emulsion), cosmetics, food industry, petroleum processing.