In chapter 2, what is the significance of the chapter's title, "Fire on the Mountain"?

Fire is symbolic in the novel.  Fire is generally a symbol of civilization, but the boys, twice, let fire get out of control.  The first time the fire gets out of control it is purely unintentional - they have set a signal fire.  The second time the fire gets away from them, they have started it to smoke out Ralph.  The boys go from using fire as a form of civility to using it as a form of savagery.