Unleaded petrol

Gasoline or gas in American English, or petrol in British English, is a colorless petroleum-derived flammable liquid that is used primarily as a fuel in spark-ignited internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. On average, a 42-U.S.-gallon (160-liter) barrel of crude oil yields about 19 U.S. gallons (72 liters) of gasoline (among other refined products) after processing in an oil refinery, though this varies based on the crude oil assay. The characteristic of a particular gasoline blend to resist igniting too early (which causes knocking and reduces efficiency in reciprocating engines) is measured by its octane rating which is produced in several grades. Tetraethyl lead and other lead compounds are no longer used in most areas to increase octane rating (still used in aviation and auto-racing). Other chemicals are frequently added to gasoline to improve chemical stability and performance characteristics, control corrosiveness and provide fuel system cleaning. Gasoline may contain oxygen-containing chemicals such as ethanol, MTBE or ETBE to improve combustion. Gasoline used in internal combustion engines can have significant effects on the local environment, and is also a contributor to global human carbon dioxide emissions. Gasoline can also enter the environment uncombusted, both as liquid and as vapor, from leakage and handling during production, transport and delivery (e.g., from storage tanks, from spills, etc.). As an example of efforts to control such leakage, many underground storage tanks are required to have extensive measures in place to detect and prevent such leaks. Gasoline contains benzene and other known carcinogens. 'Gasoline' is a North American word that refers to fuel for automobiles. The Oxford English Dictionary dates its first recorded use to 1863 when it was spelled 'gasolene'. The term 'gasoline' was first used in North America in 1864. The word is a derivation from the word 'gas' and the chemical suffixes '-ol' and '-ine' or '-ene'. However, the term may also have been influenced by the trademark 'Cazeline' or 'Gazeline'. On 27 November 1862, the British publisher, coffee merchant and social campaigner John Cassell placed an advertisement in The Times of London: This is the earliest occurrence of the word to have been found. Cassell discovered that a shopkeeper in Dublin named Samuel Boyd was selling counterfeit cazeline and wrote to him to ask him to stop. Boyd did not reply and changed every ‘C’ into a ‘G’, thus coining the word 'gazeline'. In most Commonwealth countries, the product is called 'petrol', rather than 'gasoline'. 'Petrol' was first used in about 1870, as the name of a refined petroleum product sold by British wholesaler Carless, Capel & Leonard, which marketed it as a solvent. When the product later found a new use as a motor fuel, Frederick Simms, an associate of Gottlieb Daimler, suggested to Carless that they register the trademark 'petrol', but by that time the word was already in general use, possibly inspired by the French pétrole, and the registration was not allowed. Carless registered a number of alternative names for the product, but 'petrol' nonetheless became the common term for the fuel in the British Commonwealth. British refiners originally used 'motor spirit' as a generic name for the automotive fuel and 'aviation spirit' for aviation gasoline. When Carless was denied a trademark on 'petrol' in the 1930s, its competitors switched to the more popular name 'petrol'. However, 'motor spirit' had already made its way into laws and regulations, so the term remains in use as a formal name for petrol. The term is used most widely in Nigeria, where the largest petroleum companies call their product 'premium motor spirit'. Although 'petrol' has made inroads into Nigerian English, 'premium motor spirit' remains the formal name that is used in scientific publications, government reports, and newspapers.