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Butane is a gaseous component of natural gas, much like gasoline is a component of crude oil. While petroleum products like gasoline are refined, natural gas products are extracted. Butane can also be produced from crude oil, but in much smaller quantities. It is often added to regular gasoline to boost its performance without creating a highly volatile product. The gas is also used in refrigeration and heating systems, and as fuel for cigarette lighters.
The chemical formula for butane is C4H10, which means the molecule consists of four carbon atoms surrounded by ten hydrogen atoms to form a straight line. It looks a bit like a four-segment carbon caterpillar with ten hydrogen legs. This form is technically called n-butane, where the n stands for "normal." It has a relative called isobutane, which is used primarily as a replacement for the refrigerant freon in refrigerator systems.
Butane is one of dozens of gases derived from raw natural gas. It is often combined with propane to form a product called liquid propane gas (LPG). This is the bottled gas sold for use in camping stoves and outdoor gas-powered grills. Propane may deliver more energy, but butane has a certain property that makes it ideal for containment: when compressed, it becomes a liquid very quickly. Once it is released into the air, however, it reacts with an ignition source to become a highly flammable gas. Unlike some other natural gas derivatives, the gas only releases carbon dioxide as a waste product, not carbon monoxide.
People can take a close look at a transparent cigarette lighter to see butane in its liquid state. Once the holder depresses a valve, the liquid loses its pressure and becomes gaseous again. The flame is similar to a burning candle, because butane is considered a "paraffin" gas. The liquid that remains in the lighter is slowly expelled, much like how the candle wick only draws enough liquid wax to maintain the flame.