Paraffin or alkane is the common name for all saturated, aliphatic hydrocarbons of the chemical formula CnH2n+2. At room temperature and pressure the first four members of the normal series (Methane, Ethane, Propane and Butane) are gases, the next thirteen are liquids, while the rest are solids. The paraffins are the least toxic of all hydrocarbons. The name paraffin is also commonly used for an oily petroleum distillate, which is a mixture of hydrocarbons. It is believed that the perceived chemical inertness of the compounds led to the name paraffin from parum (little) and affinis (related).