. How does Johnson use irony when revealing the identity of the thief who stole the narrator's tuition money? What does the narrator say about it?

Irony can be found in the fact that the thirf (the porter) lent him $15.00 after stealing his money, and then helped him travel to Jacksonville by train.

There is further irony in the fact that only when the narrator meets up with the porter again and conscientiously repays the "borrowed" $15 does he begin to observe the porter and realize that he was the probably the thief.