IGNITION

(Lat. ignis, fire.) The act of setting fire to, or of taking fire; as opposed to combustion or burning, which is a consequence of ignition. The term spontaneous ignition is applied to cases in which substances take fire without previous application of heat: thus spongy platinum is said to become spontaneously ignited when introduced into a mixture of oxygen nnd hydrogen gases, and to cause their com busti on. The particles of steel struck off by collision with flint become ignited on pa ing through the air, and falling upon gunpowder, ignite it, nnd combustion ensues. Iron wire, when red hot, is also often said to be ignited, or in a state of ignition; and when in that state it is plunged into oxygen gas, or into chlorine, it undergoes combustion, and burns in those gases with the farther extrication of heat and light. [s. 603]