| Quote #1
Miss Swartz, the rich woolly-haired mulatto from St. Kitt's, on the day Amelia went away, she was in such a passion of tears that they were obliged to send for Dr. Floss, and half tipsify her with sal volatile [...] Miss Jemima had already whimpered several times at the idea of Amelia's departure; and, but for fear of her sister, would have gone off in downright hysterics, like the heiress (who paid double) of St. Kitt's. Such luxury of grief, however, is only allowed to parlour-boarders. (1.25)
From the very beginning, it's amazing how complex the social ranking of each character is. Here, we've got the mixed-race orphan heiress. She is half-Jewish, half-Jamaican, which lowers her standing (in that racist and anti-Semitic time). However, she is super-rich, which is a social plus, so she is allowed to come to this elite school and allowed special treatment (the doctor, the excess tears). But of course, she has to pay double for this privilege, reinforcing her inferior position.
| Quote #2
The humble calling of her female parent Miss Sharp never alluded to, but used to state subsequently that the Entrechats were a noble family of Gascony, and took great pride in her descent from them. And curious it is that as she advanced in life this young lady's ancestors increased in rank and splendour. (2.12)
Though Becky might not allude to it, the narrator does – an "entrechat" is a kind of ballet leap. It may help to realize that at this time, female dancers were considered only a step or two from being prostitutes (see, for example, Degas's paintings of ballerinas).
| Quote #3
[Dobbin's] parent was a grocer in the city: and it was bruited abroad that he was admitted into Dr. Swishtail's academy upon what are called "mutual principles"--that is to say, the expenses of his board and schooling were defrayed by his father in goods, not money; [...] The jokes were frightful, and merciless against him. "Hullo, Dobbin," one wag would say, "here's good news in the paper. Sugars is ris', my boy." Another would set a sum--"If a pound of mutton-candles cost sevenpence-halfpenny, how much must Dobbin cost?" and a roar would follow from all the circle of young knaves, usher and all, who rightly considered that the selling of goods by retail is a shameful and infamous practice, meriting the contempt and scorn of all real gentlemen. (5.1-2)
So the class system is so ingrained and important that even kids know the drill and can use it as bullying fodder. There are two funny/ironic things here: 1) England would collapse if not for its merchant class at this time (the 19th century was a time of huge capitalist expansion); and 2) it's Dobbin's dad's awesome tradesman skills that eventually earn him a title.