Gasworks
A gasworks or gas house is an industrial plant for the production of flammable gas. Many of these have been made redundant in the developed world by the use of natural gas, though they are still used for storage space. Early gasworks Coal gas was introduced to Great Britain in the 1790s as an illuminating gas by the Scottish inventor William Murdoch. Early gasworks were usually located beside a river or canal so that coal could be brought in by barge. Transport was later shifted to railways and many gasworks had internal railway systems with their own locomotives. Early gasworks were built for factories in the Industrial Revolution from about 1805 as a light source and for industrial processes requiring gas, and for lighting in country houses from about 1845. Country house gas works are extant at Culzean Castle in Scotland and Owlpen in Gloucestershire. Equipment A gasworks was divided into several sections for the production, purification and storage of gas. Retort house This contained the retorts in which coal was heated to generate the gas. The crude gas was siphoned off and passed on to the condenser. The waste product left in the retort was coke. In many cases the coke was then burned to heat the retorts or sold as smokeless fuel. Condenser This consisted of a bank of air-cooled gas pipes over a water-filled sump. Its purpose was to remove tar from the gas by condensing it out as the gas was cooled. Occasionally the condenser pipes were contained in a water tank similar to a boiler but operated in the same manner as the air-cooled variant. The tar produced was then held in a tar well/tank which was also used to store liquor. Exhauster An impeller or pump was used to increase the gas pressure before scrubbing. Exhausters were optional components and could be placed anywhere along the purifying process but were most often placed after the condensers and immediately before the gas entered the gas holders. Scrubber A sealed tank containing water through which the gas was bubbled. This removed ammonia and ammonium compounds. The water often contained dissolved lime to aid the removal of ammonia. The water left behind was known as ammonical liquor. Other versions used consisted of a tower, packed with coke, down which water was trickled. Purifier Also known as an Iron Sponge, this removed hydrogen sulfide from the gas by passing it over wooden trays containing moist ferric oxide. The gas then passed on to the gasholder and the iron sulfide was sold to extract the sulfur. Waste from this process often gave rise to blue billy, a ferrocyanide contaminant in the land which causes problems when trying to redevelop an old gasworks site. Benzole plant Often only used at large gasworks sites, a benzole plant consisted of a series of vertical tanks containing petroleum oil through which the gas was bubbled. The purpose of a benzole plant was to extract benzole from the gas. The benzole dissolved into the