EXPLOSION, in natural philosophy, a sudden and violent expansion of an aerial or other elastic fluid, by which it instantly throws off any obstacle that happens to be in the way, sometimes with incredible force, and in such a manner as to produce the most astonishing effects upon the neighbouring objects. Explosion differs from expansion, in that the latter is a Difference gradual and continued power, acting uniformly for some between ex-time; whereas the former is always sudden, and only plosion and expansion. The expansions of solid substances do not terminate in violent explosions, on account of their slowness, and the small space through which