The theory of the photographic process

Although we recognize the increasing importance of photographic processes based on materials other than silver halide, we do not consider it feasible to include a thorough treatment of nonsilver processes in a book of this size and still treat the silver halide photographic system with the thoroughness accorded it in the earlier editions. We accordingly confine the treatment in this book to the silver halide system, and acknowledge that the scope is not as comprehensive as the title might imply. - Preface to the third edition.