NEW BOOKS Les fondements de l a thborie de la relativitb gbnbrale. Thborie unitaire de la gravitation et de l’electricitb. S u r l a structure cosmologique de l’espace. By A. EINSTEIN. Translated from the German by Maurice Solovine. 111 pp. Paris: Hermann et Cie, 1933. Price: 35 francs. The first two sections of this small volume dealing with general relativity and with the unitary theory of electricity and gravitation are translations of two papers published, the first one in 1916, the second one in 1931. As far as these two articles are concerned, the present volume will be of use mainly to those who prefer French to German or to whom this translation is more easily accessible than the original publications. The third section on the cosmological structure of space is translated from amanuscript prepared in September, 1932. Einstein concludes that in a dynamic theory of the universe, the existence of an average density of matter different from zero must not be related theoretically to a curvature of space but to a spatial expansion. I n the light of our present knowledge, there is no sure indication of spatial curvature, positive or negative. F. H. MACDOWALL. Die phvsikalische Chemie der Kesselstein Bildung u n d ihrer Verhutung. Second revised and enlarged edition. By R.STUMPER.74 pp.; 18 illustrations. Stuttas part of collection, gart: Ferdinand Enke, 1933. Price: paper, 5.30 R.M.; 4.80 R.M. It is only three years since the first edition of this pamphlet appeared, which is an indication of how well it has been received. I n it the author has collected the most plausible theories of boiler scale formation and methods of combatting it. It is a clear exposition of the physico-chemical equilibria of scale formation, the formation of solid and crystalline phases in supersaturated solutions, and anexplanation of the effect of evaporation and colloids on scale formation. This edition discusses silicate scales, the solubility of scale constituents at operating boiler temperatures and pressures, and the dynamics of carbonate scale formation. Old and new methods of scale prevention by shifting of chemical equilibria, by means of colloids, mechanically, and electrically are critically considered. Throughout this pamphlet are given excellent tables of data, graphs, illustrations, some calculations, and many literature references. The subject matter is very well treated from the theoretical standpoint. Practical calculations and applications would make the pamphlet more useful to the practicing engineer. CHARLES A. MANN.
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T h e Conductiaity of Solutions. Second edition. By CECILW. D A ~ I E S .viii 281 pp.; 32 figs. New York: John Wiley and Sons, Inc., 1933. Price: $4.00. This book may be recommended as an interesting, easily readable, but hardly adequate presentation of modern theories of the electrical conductance of solutions. The standpoint of the author seems to be that chemists need not understand the equations of Debye or of Onsager but should only be concerned with their success in 245
