Electric light be made with a screw-thread base, two metal pins, two metal caps or a bayonet cap. The three main categories of electric lights are incandescent lamps, which produce light by a filament heated white-hot by electric current, gas-discharge lamps, which produce light by means of an electric arc through a gas, and LED lamps, which produce light by a flow of electrons across a band gap in a semiconductor. Before electric lighting became common in the early 20th century, people used candles, gas lights, oil lamps, and fires. Cornish chemist Humphry Davy developed the first incandescent light in 1802, followed
Royal Pharmaceutical Society history, and include: Since 2002 the Society has concentrated on developing the collection of historical and contemporary proprietary medicines. The museum is open to visitors and admission is free. Guided tours are available if booked in advance. In 1983 the Royal Pharmaceutical Society of Great Britain donated over 10,000 historic specimens of materia medica, including crude drugs, herbarium sheets and slides to the Royal Botanic Gardens, Kew. This material is now housed in the Economic Botany Collection (EBC) at Kew. The museum is a member of the London Museums of Health & Medicine. The three boards provide professional leadership and