A method and apparatus for dispersing an active ingredient, such as a £umigant, fertilizer or room freshener. The active ingredient is placed in a container (13) and a pressurised solvent/propellent is subsequently introduced from a source (11). The solvent/propellent expands to adopt a liquid phase and a gaseous phase. The liquid phase serves to absorb the active ingredient and the gaseous phase serves to propel the borne active ingredient out of the apparatus through a dispensing outlet (14) where further expansion takes place and the active ingredient is dispersed in a fog or mist. Check valves (15, 16) create a pressure differential between the sample cylinder outlet (23) and a by-pass portion (22) to enable total absorption of the active ingredient. The system is particulary suitable for the spraying of insecticides where a metered amount of active ingredient is to be dispersed or for exhausting a total supply of active ingredient.