Chemistry and Physics. 349 



of Hallwachs, Fredenhagen and Kiistner bids fair lo simplify and 

 perhaps revolutionize certain chapters of the subject, so that the 

 volume will greatly facilitate the comparison and adjustment of 

 the earlier and latest ideas and results. h. s. u. 



8. An Introduction to the Mathematical Theory of Attrac- 

 tion ; by Francis A. Tarleton. Vol. II, pp. xi, 207. London, 

 1913 (Longmans, Green & Co.). — In the preface to the first 

 volume, which was published about fourteen years ago, (see vol. 

 viii, page 88, 1899) the author says : "... I hope, at some future 

 time, to make this book more complete by the addition of chap- 

 ters dealing with Spherical Harmonics, Conjugate Functions, and 

 the Theory of Magnetism for bodies having finite dimensions." 

 This hope is fulfilled by the present volume, which begins with 

 chapter eight and ends with chapter twelve. The original plan 

 has been departed from in two respects, namely, the subject of 

 conjugate functions has been omitted and a chapter on Maxwell's 

 theory of light has been added. The more recent developments 

 of the electromagnetic theory of light are not touched upon. The 

 treatment lays more stress on the mathematical than on the 

 physical aspects of the topics discussed. The analysis would 

 have been simplified and made more elegant and up-to-date if the 

 author had used vector methods instead of scalar notation. The 

 index is immediately preceded by a " Note on Thomson and 

 Dirichlet's Theorem." h. s. u. 



9. The Chemistry of the Radio-elements. Part II. The 

 Radio-elements and the Periodic Law • by Frederick Soddy. 

 Pp. v, 46. London, 1914 (Longmans, Green and Co.). — This 

 little book deals with the following topics: The periodic table. 

 Chemical and electro-chemical advances. The connection between 

 the sequence of changes and the chemical properties of the pro- 

 ducts. The branching of the disintegration series. Nature of 

 the end products. Atomic weight of lead. The origin of 

 actinium. The spectra of isotopes. Neon and metaneon. 

 Nature and properties of isotopes. The structure of atoms. 

 Nature of the argon gases. The definitions of the new words 

 " isotope " and " isotopic " may merit quotation. "... a group 

 of two or more elements occupying the same place in the Periodic 

 Table, and being in consequence chemically non-separable and 

 identical, will be referred to as a group of isotopes, and, within 

 the group, the separate members will be referred to as isotopic." 

 "Thus ionium, thorium, and radio-thorium are isotopes, and 

 mesothorium 1 is isotopic with radium." h. s. it. 



10. Modern Seismology ; by G. W. Walker. Pp. xii, 88 ; 13 

 figures and 13 plates. London, 1913 (Longmans, Green and Co.). 

 — The first five chapters of this book relate to seismometry and 

 the remaining five to seismogeophysics. More specifically, the 

 first 36 pages treat of the general dynamical theory of seismo- 

 graphs and the installation, standardization, sensitiveness, damp- 

 ing, mechanical and electromagnetic registration of the five chief 

 types of seismographs in actual use. The rest of the text is 



