Damps

a name given to certain poisonous gases formed in mines. Miners distinguish two kinds--choke damp and fire damp. Choke damp is composed largely of carbonic acid gas, and is found in the lowest levels. It will extinguish the flame of a candle. No one can live in it for a long time. Fire damp also contains carbon, combined with hydrogen and mixed with atmospheric air. It explodes in contact with a flame. Miners going to their work with lighted candles or lamps not infrequently run into fire damp before they are aware of it. Violent explosions result in the death of many men. As early as 1815 Sir Humphry Davy invented a safety lamp which consisted essentially of a cylinder of wire gauze surrounding the flame. Fire damp passes through the meshes of the gauze and burns within with a feeble blue flame. The flame of the lamp cannot pass out through the gauze without being cooled to such a degree that it cannot ignite the dangerous gases. See Davy; Sir Humphry; Safety Lamp