The Phase Rule and Heterogeneous Equilibrium [antikvár]

Preface Classical chemistry, by which is meant not something outmoded but what is still the bulk of chemical investigation, rests upon the identification and characterization of substances and upon the study of their interaction. Implicitly or explicitly we apply the principles of the Phase Rule in almost all such considerations. Some of these principles are so clear and familiar that the systematic exposition of the theory may seem to some to be unnecessary. The subject, however, although of obvious fundamental importance, is at times only apparently simple, and deceptively so. The purpose of this book is to offer a systematic study of the meaning and application of the Phase Rule which may be general enough to be used as reference for almost any application of the principles. Since the principles of phase diagrams are fundamentally simple, the emphasis has been placed on the interconnection between the familiar diagrams of systems of various orders, or numbers of components. The attempt has been made to point out and utilize as much as possible the basic identity of typical diagrams for a variety of relations. This includes, for example, the use of the freezing point diagrams of systems of lower order for the representation of the isothermal evaporation of systems of higher order, through the analogy between the variable of temperature for isobaric systems and the isothermal variable of water content for higher order aqueous systems. The principal difference between the systematic exposition here attempted and that usually followed lies, perhaps, in starting with continuous miscibility in all states as the simplest possibility both in binary and in ternary systems, and introducing thereupon the complications caused by the occurrence of a miscibility gap in a particular state. A degree of generality of point of view, and of economy of discussion, seems in this way to be obtainable far beyond what can be done, in the writer's opinion, througli the usual approach of introducing sohd solution as a complication rather than as a fundamentally simple relation. Although the book is concerned primarily with the underlying principles rather than with detailed examples and applications, an attempt has been made to include specific illustrations of the more important and interesting relations. The book is not intended, however, to serve as source of numerical information on any particular substance or system of substances. The accumulation of "phase rule measurements" is beyond even the capacity