One of the most salient and inspirational figures in psychological and educational research of the 20th century, Piaget was also prolific, authoring or editing over 80 books and numerous papers. This volume is the second in a set of nine which reproduce his original texts.

Part 1 Conservation; Chapter 1 The Conservation of Matter and Deformations of a Ball of Modelling Clay; Chapter 2 The Conservation of Weight upon Deformations of a Clay Ball1In collaboration with Kiazim Osman.; Chapter 3 The Conservation of Volume at Equal Concentrations of Matter; Part 2 From Conservation to Atomism; Chapter 4 The Destruction of Matter and the Dissolution of Sugar; Chapter 5 The Conservation of the Sugar and the Beginning of Atomism; Chapter 6 The Conservation of the Weight and Volume of the Dissolved Sugar and the Completion of Atomism; Part 3 Compression, Decompression and Density; Chapter 7 The Expansion of a Maize Seed and of a Column of Mercury1In collaboration with Nelly Gruner.; Chapter 8 Differences in Density; Chapter 9 Special Problems Posed by the Relationship between Weight and Quantity of Matter1In collaboration with Trude Strauss.; Part 4 Formal Compositions; Chapter 10 The Composition of Asymmetrical Relations and Differences in Weight; Chapter 11 Simple and Additive Compositions of Equivalent Weights1In collaboration with Mme Ingold-Favroz-Coune.; Chapter 12 Simple and Additive Compositions of Equivalent Volumes and the Discovery of the Displacement Law;