IGNITION

(Lat. ignis, ^re.) 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 and hydrogen gases, and to cause their combustion. The particles of steel strtck off by collision with flint become ignited on pa ing through the air, and falling upon gunpowder ignite it, and 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 further extrication of heat and light. [s. 598]