At the start of the novel, the narrator introduces Carrie’s naive worldview by employing verbal irony and foreshadowing. They hint at the vast changes and travels awaiting her:
To be sure there was always the next station, where one might descend and return. There was the great city, bound more closely by these very trains which came up daily. Columbia City was not so very far away, even once she was in Chicago. What, pray, is a few hours—a few hundred miles?
Dreiser uses the phrase "to be sure" in the novel many times. Every instance of this phrase is a moment of verbal irony. While ostensibly denoting confidence or certainty, “to be sure” in Sister Carrie is almost always utilized in contexts where a character is on the cusp of a misunderstanding or miscalculation. It's dangerous, Dreiser implies, "to be sure" of anything.
Here, the irony lies in Carrie’s sense of surety in the face of her limited experiences: "What, pray, is a few hours—a few hundred miles?" For someone like Carrie—who has never ventured outside of Wisconsin—such distances would have been monumental. Before high-speed travel like airplanes and cars became widely available, moves like her relocation from Wisconsin to Chicago would have been major lifetime events.
The passage also foreshadows the trajectory of Carrie's life. Throughout the course of the novel, the protagonist will make some major geographical moves, and this quote hints at the various cities and experiences in her future. The allusion to "the next station" and the possibility of descent and return suggests the choices and changes coming to Carrie's life. The implication is that once Carrie is swept away by her new life, a return to her roots will become an increasingly remote possibility. The phrase, "Columbia City was not so very far away, even once she was in Chicago," subtly emphasizes this impending chasm between her past and future.
When Hurstwood and Drouet see a prominent spiritualist entering the bar they’re drinking at, they engage in a wry back-and-forth full of verbal irony:
"See that fellow coming in there?" said Hurstwood, glancing at a gentleman just entering, arrayed in a high hat and Prince Albert coat, his fat cheeks puffed and red as with good eating. [...]
“Who is he?”
“That’s Jules Wallace, the spiritualist.”
Drouet followed him with his eyes, much interested.
“Doesn’t look much like a man who sees spirits, does he?” said Drouet.
“Oh, I don’t know,” returned Hurstwood. “He’s got the money, all right,” and a little twinkle passed over his eyes.
Hurstwood's comments here are highly ironic, but they seem to be somewhat lost on the more gullible Drouet. A “spiritualist” was someone who believed in communicating with the spirits of the deceased, often through mediums or séances. This movement gained significant popularity in both the United States and Europe in the Victorian period. Many adherents paid significant sums to “mediums” who claimed to be able to contact the dead. Drouet's statement suggests Wallace doesn't resemble a spiritualist who communicates with the deceased because he’s richly dressed and pink in the face.
Hurstwood's response, however, hints at another kind of "spirit." He thinks that the only kind of “spirit” this man “sees” regularly comes in a bottle. The phrase "He’s got the money, all right" is a witty insinuation with a double meaning, which the author emphasizes by mentioning the “twinkle” in Hurstwood’s eye. Spiritualists divided public opinion: lots of people believed in their abilities, but many others thought that they were quacks who exploited vulnerable people for their own gain. Here, Hurstwood is implying that Wallace has the means to "see spirits" in the form of expensive liquors because of the profits from his dubious career.
