Natural-gas processing at ambient conditions (i.e., pentane and heavier) are called "natural-gas condensate" (sometimes also called "natural gasoline" or simply "condensate"). Natural gas is called "sweet gas" when relatively free of hydrogen sulfide; gas that does contain hydrogen sulfide is called "sour gas". Natural gas, or any other gas mixture, containing significant quantities of hydrogen sulfide, carbon dioxide or similar acidic gases, is called "acid gas." Raw natural gas can also come from methane deposits in the pores of coal seams, and especially in a more concentrated state of adsorption onto the surface of the coal itself. Such gas is referred to
Natural gas etc.). Quantities of natural gas are measured in normal cubic meters (cubic meter of gas at "normal" temperature and pressure ) or standard cubic feet (cubic foot of gas at "standard" temperature and pressure ), . The gross heat of combustion of commercial quality natural gas is around , but this can vary by several percent. This is about (assuming a density of , an approximate value). Gas prices for end users vary greatly across the EU. A single European energy market, one of the key objectives of the EU, should level the prices of gas in all EU member