Manufactured gas became one of the first networked production and distribution enterprises along with water and sewer systems of nineteenth-century cities. It preceded by decades the development of technological systems such as trolley, telephone and electric systems to create an integrated infrastructure. Paving city streets had a similar networking effect. Manufactured gas lasted for 170 years before it was replaced by natural gas. Its history began with mining coal, transporting it by wagon, barge and eventually railway. It required combustion without oxygen to produce coke, in a retort (a sealed oven). The retort captured the coal gas released from the production of coke. Purification and storage came last in this process but before transportation. Transporting the purified gas through a network of pipes to streets, commercial buildings and the homes of elites for lighting transformed urban life in ways unimaginable in the decades before. Over many decades, natural gas replaced manufactured gas. Natural gas, composed of mostly methane is the cleanest fossil fuel. Similar to oil, the organisms that lived in the oceans millions of years ago provided the substance that eventually became oil and gas.