So the trader only regarded the mortal anguish which he saw working in those dark features, those clenched hands, and suffocating breathings, as necessary incidents of the trade, and merely calculated whether she was going to scream, and get up a commotion on the boat; for, like other supporters of our peculiar institution, he decidedly disliked agitation.
This scene does well to show us the apathy of Haley, who callously sells this woman's child right out from underneath her the moment she steps away. He is more preoccupied with the idea of her raising a fuss or making a scene than how much agony she's in, the hurt he has caused and the inhumanity of selling a living, breathing, ten month old child. In this he is seeing profit and damage control, nothing more and nothing less. It makes note of how desensitized he has become to the reactions of women who he does this to, and the relief he felt in seeing her shut down and cry in a calmer manner. Even describing it as an advantage.