Bitumen, any of various naturally occuring mixtures of hydrocarbons with their non-metallic derivatives. Crude petroleum, asphalt and tar are bitumens, which are characteristically dark brown or black and which contain little nitrogen, oxygen or sulphur. Commercially the term bitumen refers chiefly to hydrocarbons in a solid or semi-solid state, but in a wider sense it refers to all natural hydrocarbons, which may also occur in a liquid or gasses state. Bitumen distributed in various location throughout the world, is found in all geological bitumen was the Roman name for an asphlat which is used in binder road construction. It is an extremely viscous liquid at a ambient temperature and hard to use. Bitumen can be converted into a workable state :