History of chemistry iodine first, but both scientists acknowledged Courtois as the first to isolate the element. In 1815, Humphry Davy invented the Davy lamp, which allowed miners within coal mines to work safely in the presence of flammable gases. There had been many mining explosions caused by firedamp or methane often ignited by open flames of the lamps then used by miners. Davy conceived of using an iron gauze to enclose a lamp's flame, and so prevent the methane burning inside the lamp from passing out to the general atmosphere. Although the idea of the safety lamp had already been demonstrated by
Safety lamp but cannot pass to the outside. In the Geordie lamp the inlet and exhausts are kept separate. Restrictions in the inlet ensure that only just enough air for combustion passes through the lamp. A tall chimney contains the spent gases above the flame. If the percentage of firedamp starts to rise, less oxygen is available in the air and combustion is diminished or extinguished. Early Geordie lamps had a simple pierced copper cap over the chimney to further restrict the flow and to ensure that the vital spent gas did not escape too quickly. Later designs used gauze for the