What are the themes in chapter 22 of "To Kill a Mockingbird"?
One of the most important themes of chapter 22 is the loss of innocence. The trial of Tom Robinson has finally concluded. The verdict, as expected, was guilty, despite overwhelming evidence of Tom's innocence. Just as Tom's innocence is no more, so too the children have had their innocence suddenly taken away by this miscarriage of justice. Both Scout and Jem naively thought that the adult members of the jury would see sense and acquit Tom of all charges. However, that was never going to happen.
Jem in particular seems shattered by the verdict. He actually sheds tears over the sheer injustice of it all. He also tells Miss Maudie that he always thought that the people of Maycomb were the best in the world. Now, he no longer believes that. Jem's sudden contempt for the whole adult population of Maycomb is then heightened when he finds out about Bob Ewell spitting in Atticus's face. Miss Maudie may try to convince Jem that there are still genuinely good people in Maycomb despite Tom Robinson's conviction, but there can be no going back to his prior state of innocence, now irretrievably lost.
In an abstract sense, the themes of this chapter are the themes of the entire book; they are just given a different emphasis. That said, I'd say that the themes shown in this chapter are first of all the pain caused by racism, the different forms of cowardly hypocrisy, and how heroism can take different forms. The racism is shown in the gossiping, as is the hypocrisy. Ewell's spitting at Atticus is definitely cowardly, and Atticus' calm response is a kind of moral heroism. Likewise, Judge Taylor's choice of Atticus as a defender is a kind of quiet heroism; he's setting his town up to change.