Just in time for the next season of Mad Men, someone has posted the book, Scientific Advertising, in its entirety at: http://scientificadvertising.blogspot.com/
From the website: “One of the greatest copywriters of all time, Claude Hopkins invented sampling, risk-free trials, money-back guarantees, market testing and other breakthrough advertising techniques… . First published in 1923, Scientific Advertising is as relevant today as it was 80 years ago. Indeed, David Ogilvy said of it, ‘Nobody should be allowed to have anything to do with advertising until he has read this book seven times. It changed the course of my life.’”