It is a pleasure to present this volume consisting of a selection of papers presented at the 4th International Drying Symposium (IDS) held in Kyoto, July 9-12, 1984, under the sponsorship of the Society of Chemi cal Engineers, Japan. This book includes full texts of the ten keynote lectures and several papers which were presented in the technical sessions in the 4th IDS. As editors we had the arduous and unpleasant task of selecting papers for this volume. We were delighted with the high quality manuscripts sub mitted. We are grateful to the authors for their efforts in meeting the manuscript...