Originally published in 1970, this book gives a comprehensive account of the properties of ice, the connections between them and the way in which they derive from the structure of the water molecule and the small mass of the proton. The properties are discussed in terms of quantum mechanics and solid state theory with emphasis on physical principles rather than on theoretical models. The book is intended as an exemplification of the principles of chemical physics for beginning graduate students in physics of physical chemistry and as a text and reference book on the properties of ice for research workers in glaciology, cloud physics, meteorology and associated fields. Although the author assumes a familiarity with fundamental physics, he has taken some trouble to make his account self-contained by reference to the underlying principles in every case or by more detailed discussion where the application is not a standard one.