2. Dejection; depression; cloud of the mind. Even now, while thus i stand blest in thy presence, a secret damp of grief comes o'er my soul. (Addison) It must have thrown a damp over your autumn excursion. (j. D. Forbes)
3. (Science: chemical) a gaseous prodact, formed in coal mines, old wells, pints, etc. Choke damp, a damp consisting principally of carboni acid gas; so called from its extinguishing flame and animal life. See carbonic acid, under carbonic. Damp sheet, a curtain in a mine gallery to direct air currents and prevent accumulation of gas. Fire damp, a damp consisting chiefly of light carbureted hydrogen; so called from its tendence to explode when mixed with atmospheric air and brought into contact with flame.