From detonate. Detonating gas, a mixture of two volumes of hydrogen with one volume of oxygen, which explodes with a loud report upon ignition. Detonating powder, any powder or solid substance, as fulminate of mercury, which when struck, explodes with violence and a loud report. Detonating primer, a primer exploded by a fuse; used to explode gun cotton in blasting operations. Detonating tube, a strong tube of glass, usually graduated, closed at one end, and furnished with two wires passing through its sides at opposite points, and nearly meeting, for the purpose of exploding gaseous mixtures by an electric spark, as in gas analysis, etc.