LPG is a mixture of hydrocarbons (propane and butane) in a gaseous state. In a liquid state it exists only at very low temperatures or under pressure. As a liquid it occupies 1 / 250 of the volume of gas and thus can more easily stored in containers. The LPG gas is colorless and odorless. Therefore a very smelly substance is added prior to disposal for consumption, to facilitate detection of leaks.