Text extracted from opening pages of book: COMPLEX IONS IN AQUEOUS SOLUTIONS liY ARTHUR JAQUES, D. Sc., F. I. C. LONGMANS, GREEN AND CO. 39 PATERNOSTER ROW, LONDON FOURTH AVENUE & SOrn STREET, NEW YORK BOMBAY, CALCUTTA, AND MADRAS 1914 PREFACE IN compiling this volume the needs and criticism of a large class of students unversed in physical chemistry have heen especially kept in view, and it is considered that the introduction of some elementary matter, such as proofs of formula 1 , which the advanced reader will not require, is by no means out of place. In giving an account of the methods in Chapters 11I.-V1., it was found necessary to introduce examples, but these were made as brief as possible in order to avoid confusing these chapters with the later ones which deal with practical investigations, where more than one method is generally used at a time. The tension experiments in Chapter VIII. form a method of investigation in which the examination of different sal tar snows so little variation that it appeared unnecessary to devote a separate chapter to the method. The chief aim of the book is to give some account of the more important experimental work in this subject, and no apology is offered for the absence of theories of valency. Chapter X. contains an account of some results besides the identification of complex compounds, which have been arrived at by similar methods, and which are likely to form the basis of further experiments. A. J. 1' OLMONT, STIRLINGSHIRE, May , 1914. CONTENTS CMAIMKU PVUK I. INTRODUCTION 1 If. TIIK CHEMICAL MKTIIOD G III. TIIK IONIC MHJKATIOX MKTHOD 11 IV. TIIK PisTuinmioN MKTIIOD 20 V. TIIK SOLUIULITY MKHIOD 28 VI. THE ELKCTKICAL POFKNTIAL MKTHOD 39 VII. S() MK KXAMPLKH 41) VIII. AMMONIACAL SALT SOLUTIONS, KTC 73 IX. SoMK Coi'. ALT AND ( JOIM'KH SOLUTIONS i> 7 X. SOMK SI'KCIAL CASKS OF KQUILIUWUM 104 APPKNDIX I. TIIK HYDKATK TIIKOUY 139 IF. A TIIKOKKTUUL METHOD OF KXAMININCJ CKUTAIN SOLUTIONS 145 NAMK INDKX 147 SUH. TKCT INDKX 150 CHAPTER I INTRODUCTION A. Introductory. The suggestion that the abnormal behaviour of certain electrolytes might be accounted for by assuming the for mation of complex ions in them was first put forward by Ilittorf, who, in the course of his study of migration, made the classical discovery that the migration ratio for the anion in solutions of many double salts and certain single ones increased rapidly with increase in the concentration of the solution and at high concentrations became greater than unity. Hittorf suggested that this was due to the formation of a double salt in the solution, which gradually dis sociated on dilution. In this way our knowledge of the mode of ionisation of a number of salts in solution was established. Later, the subject was investigated by other methods, notably by pure chemical means and by cryoscopic measure ments. The latter method, however, yields somewhat uncertain results. A new method was introduced by Eoloff ( Zeit. phys. Chem. y 13, 341 ( 1894)), who measured the distribution ratio of a solute between two solvents, and showed that the in crease in the solubility of bromine in water observed on adding potassium bromide to the system is due to the for mation of the complex ion Br 3 '. Two years later Jakowkin ( Zeit. phys. Chem., 20, 19 ( 1896)), employing the same method, found that solutions of iodine and potassium iodide show similar behaviour. In the last fifteen years two new methods of investigating i B 2 COMPLEX IONS the constitution of electrolytes have been worked out, the first based upon solubility measurements and the second upon measurements of electrode potential, and a large number of complex ions have been discovered and studied by these methods. Much of this work was carried out by the late Professors Abegg and Bodliinder and their pupils. Such investigations are likely to be of value in framing a theory of chemical combination in the future. For in com plex ions we have a class of compounds in which valencies oth --This text refers to an alternate Paperback edition.