It is now time for a comprehensive treatise to look at the whole field of electrochemistry. The present treatise was conceived in 1974, and the earliest invitations to authors for contributions were made in 1975. The completion of the early volumes has been delayed by various factors. There has been no attempt to make each article emphasize the most recent situation at the expense of an overall statement of the modern view. This treatise is not a collection of articles from Recent Advances in Electro­ chemistry or Modern Aspects of Electrochemistry. It is an attempt at making a mature statement about the present position in the vast area of what is best looked at as a new interdisciplinary field. Texas A & M University John O'M. Bockris University of Ottawa Brian E. Conway Case Western Reserve University Ernest B. Yeager Texas A & M University Ralph E. White Preface to VoluIJJe 8 The past three decades have seen the rapid evolution of the transport aspects of electrochemical engineering into a formal part of electrochemistry as well as chemical engineering. With minor exceptions, however, this subject has not been systematically covered in any treatise or recent electrochemical text. The editors believe that the treatment in this volume will serve the function.