He may of told the story in other places, but I remember that it was discussed in the book Surely You're Joking, Mr. Feynman!. He would act as a bloodhound, sm

He may of told the story in other places, but I remember that it was discussed in the book Surely You're Joking, Mr. Feynman!. He would act as a bloodhound, smelling books, then having people handle the book without him present, then identifying which book a person handled by smelling their hands. I believe he did it also with playing cards after identifying the differences in the way people's hands smelled.