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 can impinge on the gauze. The shield had the disadvantage of not allowing the collier or the deputy to check that the gauze was in place and clean. Lamps were therefore made so that they could be inspected and then the bonnet placed on and locked. In the Davy lamp a standard oil lamp is surrounded by fine wire gauze, the top being closed by a double layer of gauze. If firedamp is drawn into the flame it will burn more brightly and if the proportions are correct may even detonate. The flame on reaching the gauze fails to pass