In chapter 2, what is the significance of the chapter's title, "Fire on the Mountain"?
The title has significance in that it refers to the main event of the chapter, it foreshadows other fires, and it has symbolic meaning. As the chapter opens, Ralph calls an assembly to share what the boys have learned about the island during their exploration. The meeting starts well, with both Ralph and Jack agreeing on the need for rules and Jack offering his choir members as keepers of the signal fire. The boys have fun building a twenty-foot fire that quickly seems to burn out. However, as the boys continue talking, the fire spreads to a large section of the forest, consuming a section of firewood and tragically killing the littlun with the birthmark.
Fire becomes a recurring motif in the chapter. Ralph sets the rules for where the fire should be kept, and Jack volunteers to oversee its tending, but then fails to keep it lit when a ship passes by that might have rescued them. When the "beast from air" lands near the signal fire, the boys fear to keep the fire going there, and Ralph feels beaten until Piggy suggests having the fire on the beach. Fire is also necessary to cook the meat, and Piggy's glasses are the way to start the fire. This leads to conflict as Jack steals fire and eventually steals Piggy's glasses. Finally, at the end of the novel, Jack's tribe repeats the foolishness of the fire in this chapter on a grander scale by setting the entire island on fire to smoke Ralph out of hiding. In this chapter, Piggy reprimands the boys, saying, "Now you been and set [sic] the whole island on fire. Won't we look funny if the whole island burns up?" This foreshadows the end of the book.
Finally, the fire in this chapter is symbolic of humanity. If human impulses are restrained and controlled, they achieve great benefit for individuals and society. But if they are allowed to run wild, they are immeasurably destructive. Fire, when contained and tended assiduously, provides warmth and sustenance and hope for salvation for the boys; when it's allowed to escape its boundaries, it is deadly. The runaway "fire on the mountain" represents the boys' worst impulses that will soon be released on the island, resulting in terror and death.
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.
The rash act of throwing together a fire without thought of consequences is symbolic for what is to come later in the novel. The fire caught on quickly, and took a boys life. This will be the case with the savagery that overtakes the boys later in the novel. There is no thought for consequences in that case, either.