XEW BOOKS
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appendix on methods of soil analysis. T h e size remains a t around 650 pages, and it is a very handy volume for general reading. The purpose of the book, as the author states in the preface, is “to present the student with a broad outline of the subject, including sufficient detail to give reality to the treatment, but avoiding always the tediousness of the card index record.” In this i t most admirably fits its purpose. It is a volume for the general student in soils and plant growth rather than for the specialist in some particular aspect of this field. However, the revised and up-to-date bibliography is of great value t o technicians and general students alike. One of the most important revisions has to do with the discussion of the influence of the various elements on plant growth, including both major and minor elements. The latter are classed in this revision under the general heading of stimulative or prophylactic elements,-among the metals copper, boron, manganese, zinc, and iron, ivhile among the non-metals the class includes sulfur, titanium, and silicon, as n-ell as chlorides, iodides, and fluorides. Each is discussed individually. Chapter 111, on the composition of the soil, has been entirely rewritten, and particular attention has been given to the clay fraction, including the modern concept of the structure of the clay minerals. One of the most extensive additions is that under chapter IV, dealing 11-ith soil development and classification. I n this the subject matter has been practically doubled, bringing together the latest v i e m of pedologists. At the end of the book chapters VI11 and IX have been combined under the chapter heading “Soil Fertility in S a t u r e and in Farm Practice.” The author is a t his best in this latest volume. Assisted by a number of Rothamsted colleagues he has made this revision the last word in summat’ion of present-day knowledge in this important field. 31. F. ~ I I L L E R .
A Catalogue of the Epstean Collection. Xew T o r k : Columbia University Press, 1937. Price: 31.50. Students of the history of photography and of some phases of photochemistry will welcome this catalogue of the Epstean collection. I n addition to making the collection more useful, i t will serve as a bibliography of the earlier works on photography. The collection, which is housed in the Rare Book Departments of the Columbia University Library, includes 1418 titles. The subject matter covers practically the entire field of photography, as well as some aspects of related arts and sciences. The book is attractively bound and printed. R O B E R LIVIA-GSTOS. T
RudioactivitB.
By XfME. P I E R R ECERIE. 563 pp. Paris: Hermann e t Compagnie, 1935. Price: 150 frs. I n 1910 Mme. Curie published her well known Trait6 de Radioactivitt? (two volumes), which presented with some additions the material then contained in her regular lectures a t the Sorbonne on the subject of radioactivity. Although the present book also represents her lecture course-as recently givenit would be a mistake to assume t h a t i t is a revision of the earlier treatise. I n fact no more striking evidence of the advances of nuclear chemistry and physics in tuenty-five years could be had than by noting the differences betn een these two works. I t is true that the framen-ork of the radioactive transformations in the three families had already been traced in 1910, but the law of atomic displacement in the periodic system, the significance of isotopes and radioactive indicators, the nature of gamma radiation, the origin of the actinium family, the explanation of beta- and gamma-ray spectra, the Gamow theory of the nucleus .and its energy harriei, all re-
