Preface to the Series The Research Laboratory of the Eastman Kodak Company was founded in 1913 to carry out research on photography and on the processes of photographic manufacture. The scientific results obtained in the Laboratory are published in various scientific and technical journals, but the work on the theory of photography is of so general a nature and occupies so large a part of the field that it has been thought wise to prepare a series of monographs, of which this volume is the second. In the course of the series it is hoped to cover the entire field of scientific photography, and thus to make available to the general public material which at the present time is distributed throughout a wide range of journals. Each monograph is intended to be complete in itself and to cover not only the work done in the Laboratory, but also that available in the literature of the subject. A very large portion of the material in these monographs will naturally be original work which has not been published previously, and it does not necessarily follow that all the views expressed by each author of a monograph are shared by other scientific workers in the Laboratory. The monographs are written by specialists qualified for the task, and they are given a wide discretion as to the expression of their own opinions, each monograph, however, being edited by the Director of the Laboratory and by Mrs. Schramm, who is the active editor of the series. Rochester, New York October, 1922 Preface The present monograph presents the results of investigations undertaken to determine the reduction potentials of certain organic developers, and to establish the connection between these potentials and the developing characteristics of the various compounds. It was originally intended to use both electrometric and photographic methods, but since the results obtained by the latter method are complete, it has been decided to publish these at the present time. In the course of the work a large amount of sensitometric data has been accumulated, as well as much information relative to various other aspects of the process of development. The inclusion of what may seem an unwarrantedly large amount of thesedata seems justified by the desire to render the information obtained as useful as possible for future work as well as to support the various conclusions reached. The results here presented should normally have been published in a series of papers, bct this was prevented by the interruption caused by the war, and though completed in 1919 most of the material is thus published here for the first time. The author is indebted especially to Dr. W. F. Colby of the University of Michigan, who, during the year in which he was associated with this laboratory, made many valuable suggestions as to some of the conceptions and methods of interpretation employed. Acknowledgment is due also to Mr. Kenneth Huse, who supervised the experimental work for a time. Rochester, New York October, 1922. The Theory of Development CONTENTS Page PREFACE . . . . . . . . . . . . . . 7 CHAPTER I... --This text refers to the Paperback edition.