Theory of the chemical properties of soil colloidal systems at equilibrium

The theories of model soil colloids are developed in the present work. The principal point of departure is thermodynamics, and in the first section, an effort is made to present a consistent system of chemical thermodynamics and pertinent related physical chemistry. The second section deals with the Donnan theory and some consequences of it which may have relevance for soil systems. Electrochemical measurements are also discussed. In the third section, the Gouy theory of the electrical double layer is reviewed and the theory is used to calculate ionic activities. In the fourth section, ion-exchange equations based on various models are developed. The significance of different models for soil systems is analyzed in relation to the available data. In the fifth section, a discussion is presented of the thermodynamics of soil moisture. The emphasis throughout is on the development of theory, and no effort has been made to make historical or literature surveys.