Any one of a wide variety of volatile hydrocarbon mixtures. They are sometimes obtained from coal tar, but more often they are derived from petroleum. Physical properties vary widely. The initial boiling point may be as low as 80°F (27°C), and end points may reach 500°F (260°C). Boiling ranges are sometimes as narrow as 20°F (11°C) or as wide as 200°F (110°C).