This person realizes that a salt was effective because it was impure, and he slams his window closed during a conversation with two friends. A cane gifted to this man is broken during a crime, and Richard Enfield notes that this man's signature appears on a 90 pound check given to the family of a trampled girl. That payment was owed by another man who engenders a sense of "unexpressed deformity." This character asks his lawyer, Mr. Utterson, to secure the rights of his heir, even though that heir murdered Sir Danvers Carew. For 10 points, name 
This person realizes that a salt was effective because it was impure, and he slams his window closed during a conversation with two friends. A cane gifted to this man is broken during a crime, and Richard Enfield notes that this man's signature appears on a 90 pound check given to the family of a trampled girl. That payment was owed by another man who engenders a sense of "unexpressed deformity." This character asks his lawyer, Mr. Utterson, to secure the rights of his heir, even though that heir murdered Sir Danvers Carew. For 10 points, name this physician created by Robert Louis Stevenson, who uses a potion to turn into his vicious alter-ego Mr. Hyde.
This person realizes that a salt was effective because it was impure, and he slams his window closed during a conversation with two friends.
Dr. Henry Jekyll [or Harry Jekyll; do NOT accept "Mr. Edward Hyde" at any point] 