what are some quotes that show how the conch lost its power later in the book?
After the murder of Simon, it becomes clearer and clearer that the conch no longer means what it did at the beginning of the story. While Ralph and Jack are talking about how to move forward, Ralph suggests that he will call a meeting, that he still has some authority. He says:
"I.m chief, And what about the fire? And I've got the conch - "
But Jack replies "You haven't got it with you, you left it behind. See, clever? And the conch doesn't count at this end of the island -" The thunder crashed at that instant, as though to signal that things had really changed.
Ralph's reply is an attempt to maintain that authority, claiming that the conch counts everywhere. But the hunters begin to do their dance, it appears that the idea of the hunt and the kill, etc., have gained a level of power greater than that of the conch.