Fuente: WIPO "essential oil or extracts" Apparatus 10 for extracting essential oils from plant material on a sample basis includes a service unit 14 mounted on a service vehicle 1 2, and a process unit 20 mounted on a process vehicle 1 8. The vehicles 1 2, 1 8 are in the form of trailers. They may instead be in the form of "bakkies" . The services and process units 1 4, 20 are separate and apart and are selectively connectable by means of a conduit 24. The apparatus 10 is supplied with plant material and water, and is otherwise "self-supporting. Superheated steam generated by diesel oil fluid boiler 34 is conducted to a selected one of a pair of distillation vessels 50, charged with plant material. Essential oils are separated from a distillate in a separator 56, and are analyzed in respect of one or more characteristics to obtain information about the feasibility of a commercial plant.