Chemistry and Physics. 79 



other hand, the corresponding bands for cadmium and zinc have 

 not yet been resolved into two components. The absorption lines 

 of all four metals are the first members of the combination series 

 symbolized (on Paschen's notation) as v = 2, p g — m, S, and 

 v = 1'5, S — m, P. Finally, the author computes the ionizing 

 potentials of cadmium, magnesium, mercury and zinc to be 8*85, 

 9'13, lO^* and 9*24 volts, respectively. — Proc. Hoy. jSoc, vol. 

 xcii (A), p. 305. h. s. u. 



9. A Treatise on Electricity ; by F. B. Pidduck. Pp. xiv, 

 646, with 369 figures. Cambridge, 1916 (University Press. Also 

 G. P. Putnam's Sons). — This book is not intended for beginners 

 but is designed for those readers who require an advanced text 

 covering both the theoretical and practical sides of the subject. 

 The first eight chapters have been kept fairly simple and contain 

 all the mathematical and physical principles necessary for a right 

 appreciation of the subject, while the remaining six chapters form 

 introductory accounts of special fields, which may be consulted by 

 students before starting on treatises devoted to them exclusively. 



Thus the ninth chapter, entitled "Applied Electricity," deals 

 with shunt, series, and compound wound dynamos, with direct 

 and alternating current motors, with induction motors, with elec- 

 tric lighting, etc. Chapter X, on electrolysis, is followed by a 

 longer and very interesting chapter on electric oscillations. 

 Among other things this chapter contains accounts of the experi- 

 ments of Tesla, Hertz, Bjerknes, and of Sarasin and de la Rive. 

 Coupled oscillation circuits, the singing arc, the electromagnetic 

 theoiy of light, and wireless telegraphy also receive due attention. 

 Chapter XII is devoted to the conduction of electricity through 

 gases. It is fully up to date and includes, for example, the 

 theory of the sparking potential, the phenomena of the photoelec- 

 tric effect, and the theory of the diffraction of Rontgen rays. 

 The next two chapters pertain respectively to radioactivity and 

 the theory of electrons. This last chapter involves the electron 

 theory of metallic conduction, Lorentz's equations, the theory of 

 the normal Zeeman effect, the Lorentz-Einstein transformation, 

 the theory of quanta, etc. The text has been written carefully 

 and accurately, the selection of material is excellent, and the num- 

 ber of typographical errors is very small so that the volume 

 should be found very useful by first-year graduate students in 

 particular, and by others who need an introduction to the highly 

 specialized, advanced treatises. h. s. u. 



10. The Physical Properties of Colloidal Solutions ; by E. F. 

 Burton. Pp. vii, 200. London, 1916 (Longmans, Green and 

 Co.). — "The present attempt to give an outline of the study of 

 colloidal solutions has to do particularly with its interest to the 

 student of Physics." The second chapter deals with the prepara- 

 tion and classification of colloidal solutions. It contains sys- 

 tematic tables of various classes of colloids having something in 

 common, and quotations of types of methods of preparation which 

 will enable the reader to iind out where to look for detailed 



