In the theoretical treatment the author is particularly indebted to the original articles and to the larger works of Arrhenius, van 't Hoff, Nernst, A. A. Noyes, Ostwald, and Walker. For the systematic analytical material acknowledgment is due, in particular, to Fresenius's "Qualitative Chemical Analysis," and to the important publications by A. A. Noyes and Bray in the ‹Journal of the American Chemical Society›. Some of the excellent methods of the latter authors have been adopted outright, as indicated in the text. For some special matters the author is indebted to the texts of W. A. Noyes and of Böttger. Constant references to his sources of information have been made by the author, partly as a matter of acknowledgment, and more particularly to give students and teachers the opportunity for more extended, first-hand reading on any topic of interest. References suitable for college students are indicated by the addition of («Stud.»). In two or three instances, the original source of information has been forgotten and diligent search has failed to trace it. For use in preparing any future edition of the book, the author will be glad to have his attention called to the facts by authors. The author wishes to express here his particular appreciation of the generous assistance given him by his former colleague, Prof. Alexander Smith of Columbia University, whose suggestions and advice, especially in the editing of the manuscript and proof, have been invaluable. He also wishes to make grateful acknowledgment to his colleagues, Profs. H. N. McCoy, H. Schlesinger, and Dr. Edith Barnard, to Prof. L. W. Jones of the University of Cincinnati, Prof. E. P. Schoch of the University of Texas, Prof. B. B. Freud of Armour Institute, and Prof. W. J. Hale of the University of Michigan, who have assisted him by reading the proofs or the manuscript, or by carrying out experimental studies underlying part of the work, or in other ways. Corrections of his mistakes of omission and commission, and suggestions, will be gratefully received by the author. JULIUS STIEGLITZ. CHICAGO, ‹September, 1911›. CONTENTS PART I FUNDAMENTAL PRINCIPLES CHAPTER PAGE I. INTRODUCTION 3 II. OSMOTIC PRESSURE AND THE THEORY OF SOLUTION, I 8 III. OSMOTIC PRESSURE AND THE THEORY OF SOLUTION, II 21 IV. THE THEORY OF IONIZATION: IONIZATION AND ELECTRICAL CONDUCTIVITY 33 V. THE THEORY OF IONIZATION, II: IONIZATION AND OSMOTIC PRESSURE; IONIZATION AND CHEMICAL ACTIVITY 67 VI. CHEMICAL EQUILIBRIUM. THE LAW OF MASS ACTION 90 VII. PHYSICAL OR HETEROGENEOUS EQUILIBRIUM.—THE COLLOIDAL CONDITION 118