Douglass says, “at a time like this, scorching irony, not convincing argument is needed” (lines 138–139). why does he say this, and what is it that he finds ironic?

Douglass says this because he finds the occasion ironic.  he is speaking of the fourth of july, a day when america celebrates its independence. douglass, however, notes that many americans are not free because they are slaves. thus, it is a time for irony.

Delegates: representatives who cast votes at a political party's national convention. binding: if a primary or caucus is “binding” that means the delegates won in that contest are legally bound to vote for a particular candidate at the parties national convention.a primary is a preliminary election used to determine a party's nominee for a specific office. the winner of the party's caucus, or primary, wins the party nomination for that state. then the delegates meet at their party's national party convention, which is a formal gathering of all party delegates from all states.