Did you know that miners used carbide lamps for many years before they were deemed too dangerous? It's true, they used an open flame in a coal mine, can you imagine? So you're probably wondering how one of these bad boys worked. Well I'm here to tell you. In the top of this device there is a water chamber and a lever controlling the amount of water that drips down into the carbide. The carbide creates a gas when water is introduced, this gas is called acetylyn. The acetylyn, a very flamable gas, makes its way through a tube and out the front of the lamp. This is where they expose the gas to a flame, and this creates the light they used while working in the mine.
Obviously, these have been discontinued for the safer alternative, a light bulb and a battery.