Colloidal Dispersions by Earl K. Fischer. Preface: This monograph is planned as a guide to the theory and practice of the dispersion of solids in liquid media. Throughout the writing I have had in mind readers in several pro fessional categories: one is the physical and colloid chemist who is un familiar with the technical aspects of the subject; another is the scientist in industry who is compelled by the exigencies of his work to concentrate on product development but finds that an understanding of theory is the most effective basis on which to design new products; a third is the production supervisor who is interested in the science and engineering underlying the operations in his care but who is too busy to seek their exposition in widely scattered places. There are others, I hope, who will also find the volume interesting and usable. The topics forming the substance of this book are part of the large province of colloid science. An effort has been made to provide a coherent account of the physical properties of colloidal dispersions and the methods for producing them. Innovations and refinements in research techniques have brought a new insight to the structure of these dispersions. In particular, mention should be made of methods for particle-size measurement, experimental means for gauging the interaction of dispersed particles, and new reagents that offer a measure of control for some of the physical properties. There remain, of course, unanswered questions, and the subject abounds with engaging and important research problems. This book is intended to supplement the well-known and easily ac cessible monographs on surface and colloid chemistry. Information has been drawn from diverse sources. In an effort to keep the book of moderate size I have been perplexed by the inevitable problem of selec tion, for pertinent material is to be found in the literature of many in dustries and branches of science. I have endeavored to document the work adequately and to bring subjects into their correct historical per spective. Where available information ran low, I have, on occasion, taken the liberty of speculating, and the reader will find hypotheses advanced at various points through the book.