Oil lamps are a form of lighting, and were used as an alternative to candles before the use of electric lights. Starting in 1780 the Argand lamp quickly replaced other oil lamps still in their basic ancient form. Alexander Fran癟ois Selligue (1784-1845) was a French engineer. In 1832, he patented an application of shale oil for direct illumination. Oil shale is an organic-rich fine-grained sedimentary rock containing kerogen from which liquid hydrocarbons called shale oil can be produced. His process of distilling oil shale was first described in the Journal des Connaissances Usuelles in 1834, and first used in France, in 1838. These in turn were replaced by the kerosene lamp in about 1850. In small towns and rural areas the latter continued in use well into the 20th century, until such areas were finally electrified and light bulbs could be used.