Flagellation: Most sadistic 19th century book

Flagellation in an erotic book.
Source: Arterotismo
The book recounts the experiences of Colonel Spanker and his cronies. According to Spanker's philosophy there can be no true enjoyment in whipping lower class women, prostitutes, or any other victims who willingly submit themselves. Accordingly, Spanker and his band capture a beautiful seventeen-year-old blonde and lock her up in a house in Mayfair. There she is subjected to all forms of brutal torture and sexual maltreatment. A contemporary critic called the book "the most coldly cruel and unblushingly indecent of any we have ever read ... in the English language."