\ apor-liquid equilibrium data for the system methyl ethyl ketone-n-heptane-toluene at 1 atmosphere pressure are presented. A method of determining thermodynamic consistency of the data from the Gibbs-Duhem equation THE development of azeotropic and extractive distillation as an important separation process of chemical industry has stimulated many investigations of the vapor-liquid equilibria of nonideal systems. While a large amount of data have been determined, correlations of such data in a generalized and conven-

Distillation has been and continues to be a separation method of widespread use in the chemical and petroleum industries. The design of distillation equipment to effect separations or to recover solvents requires a knowledge of vapor-liquid equilibrium compositions. With this in mind, the purpose of the investigation reported here was to obtain the necessary data for the construction of the equilirium diagrams of two binary systems. Equilibrium data for the ethyl alcohol-toluene system at 756 mm. of mercury and the ethyl alcohol-benzene system at 760 mm. of mercury are reported.

Titemperature at inner boundary T0 = temperature at outer boundary = ratio of area of complete sphere to that of sphere minus area intersected by stem ACKNOWLEDGMENT W. M. DeWitt constructed the thermal conductivity cell, . H. Reamer aided materially in obtaining the experimental results, and W. N. Lacey reviewed the manuscript.

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interpreted, rather than on the details of history itself. However, there is room for differences of opinion on the scope and emphasis of historical geology.For their intended purposes, both books are to be warmly commended. Strahler's book would seem best suited as a text for mature students who are beginning their study of the earth sciences. It is rigorous, and yet almost totally nonmathematical.Zumberge's book, on the other hand, would seem to be best suited to less-mature students, for example, students that might be found in a typical junior college. Zumberge is generally patient and careful in his explanations. This book treats an important and timely, but rather specialized, subject in the field of nuclear power generation. It was written for practising engineers who are interested in the design of large nuclear power stations and for students who have a broad background in nuclear engineering. The contributors are well-qualified specialists who have worked with these design problems in the power reactor program in England.Most of the discussion is concerned with the factors that must be considered in designing a complete nuclear plant for producing economically competitive electric power. Chapter 1, which treats the general design concept and points out subtle features and interrelationships that are easily overlooked, might be called "design philosophy." In the remaining chapters, specialists discuss the details of power plant design; this discussion begins with a short review of reactor physics and includes chapters on reactor control and instrumentation, safety, materials, fuel elements and fuel handling, graphite struc-interpreted, rather than on the details of history itself. However, there is room for differences of opinion on the scope and emphasis of historical geology.For their intended purposes, both books are to be warmly commended. Strahler's book would seem best suited as a text for mature students who are beginning their study of the earth sciences. It is rigorous, and yet almost totally nonmathematical.Zumberge's book, on the other hand, would seem to be best suited to less-mature students, for example, students that might be found in a typical junior college. Zumberge is generally patient and careful in his explanations.