cussed in very considerable detail. These are the F d i - A l , Sn-Zn-Cu, and Fe-CSi systems. There is a brief discussion of the phase rule itself, of methods of plotting, and the significance of important sections. Then follows a detailed discussion of simple entectic mixtures, solid solutions (both continuous and broken-series), compounds having congruent melting points, and systems having limited miscibility in the liquid state. The process of crystallization, state spaces and state surfaces, isothermal sections, and sections perpendicular to the plane of concentration are treated very thoroughly in every chapter. A "general law concerning contiguous state spaces" is set forth. Saturully, seven chapters devoted cxclusivcly to such discus
