a mixture of gases (mostly methane) that form in coal mines and become explosive when mixed with air
firedamp详细解释
fire.damp
n.(名词) A combustible gas, chiefly methane, occurring naturally in mines from the decomposition of coal. 沼气:一种在矿坑里由煤腐烂而自然产生的可燃气体,主要成分是甲烷 The explosive mixture of firedamp and air. 甲烷和空气的爆炸混合物