sapogenins are important enough to be described separately and sap- onins. A note to the editors: these volumes, according to the book jac- ket are for "layman and expert," alike, yet quite often the layman would be unable to follow the material for lack of a science degree. Some authors are more able to simplify a complex subject than others. These few observations do not detract from the over-all excellence of the encyclopedia. They are intended for subsequent revisions. The two editors have done a true service to chemistry and chemists. If you have the first volume, you will need this one, too. If you do not have Volume I, you need to get both.--M. G. DENAVARRE. COMPREHENSIVE INORO^NIC CHF•M- •STR¾, edited by M. C. Sneed and R. C. Brasted. D. Van Nostrand Co., Inc., Princeton, N.J. 1958. Volume VI, 234 pages, 1957. Price $6.00. Volume VII, 302 pages, 1958. Price $7.50. Volume VI of this series is de- voted to the alkali metals, material authored by John F. Suttle, and to hydrogen and its isotopes written by R. C. Brasted. The alkali metals considered are lithium, sodium, potassium, rubid- ium and cesium. Because of the similarity of the reactions of these elements, sodium is most often dis- cussed if the consideration holds true for the others. In this section is a good review of the phosphates, although a bit more could be said about the branched, chain and cyclic types. The material appears to be well presented. Volume VII deals with the ele- ments and compounds ofg.roup IVA, carbon, silicon, germanram, tin, lead, the borides, carbides, silicides and related compounds. This is written by H. P. Klug and R. C. Brasted, one of the editors. Other contributions are by O. H. Johnson and C. L. Mantell. It is interesting to note that cala- mine is zinc silicate, a source of zinc, page 61, and Willemite also being a zinc silicate, page 134. A chapter is devoted to the study of organic silicon compounds, the silicones. There is a good discussion of the clay minerals which are of consider- able cosmetic interest. Both volumes are well indexed. The text goes all the way from sim- ple chemistry to the most compli- cated molecular structures. Add these to the previous ones for a worthwhile reference set.--M. G. DENAVARRE. 116