Chemistry and Physics. 315 



obtained from the following list of the titles of the successive 

 chapters, namely : " The Physics of the Electron, The Positive 

 Particle, The New Method of Analysis, The Nature and Size of 

 an Electron, The Chemistry of the Model Atom, The Atom in 

 Vibration, The Molecular Theory of Matter, and The Atom in 

 Dissolution." Elementary proofs of certain mathematical for- 

 mulae and a table of atomic data are given in three appendices. 

 The volume closes with a short bibliography of the most import- 

 ant books and memoirs pertaining to its special field. The semi- 

 popular manner of presentation and the brevity of the text may 

 furnish sufficient reasons for the absence of an index. 



Of the several elementary books on the subject which have come 

 to our notice the present one contains the most interesting and 

 reliable account. This is due, in part at least, to the fact that the 

 author spent eight years in the Cavendish Laboratory during the 

 period when the brilliant researches of J. J. Thomson were in 

 progress. The typographical errors are fairly numerous, but of 

 such a nature, in general, as to admit of obvious correction. 



h. s. u. 



8. General Physics : Electricity, Electromagnetic Waves and 

 Sound ; by J. A. Culler, Pp. x, 321, with 224 figures. Phila- 

 delphia, 1914 (J. B. Lippincott Co.). — This is a companion vol- 

 ume to the author's " Mechanics and Heat " (see vol. xxviii, page 

 557). The endeavor has been made "(1) To make the descrip- 

 tions, proofs, statements, and illustrations clear to the average 

 student. (2) To emphasize the physical side of physics, point out 

 its applications in the commercial world, and give more than an 

 outline in the development of a topic. (3) To incorporate in the 

 body of the discussions and in their proper place the electronic 

 and electromagnetic theories now so well established." The third 

 aim, namely, the explanation of electrical phenomena in terms of 

 the electron, is the most novel feature of the text. Another 

 salient point is the treatment of the entire subject of light in the 

 chapter on electromagnetic waves. The discussion of optical 

 apparatus is enhanced by the use of the curvature of wave-sur- 

 faces, sagittas, etc. The subject of sound is wisely condensed into 

 one chapter (pages 270-293). Most of the figures are satisfactory 

 diagrams, and four are excellent half-tones. Whenever feasible 

 the chapters close with lists of problems (100 in all) w r ith numeri- 

 cal answers. The appendix contains certain proofs which involve 

 the calculus, special topics, and tables of physical and mathemati- 

 cal constants. 



In spite of the fact that the book has many admirable features 

 it is but fair to state that the information imparted is not unquali- 

 fiedly up to date. For example, on paye 247 may be found the 

 statement that " X-rays, however, cannot be reflected, refracted, 

 or diffracted, and hence no way is known by which their 

 wave-length can be determined." As a matter of fact, the deter- 

 mination of the wave-lengths of Rontgen rays is now an every- 

 day occurrence, the field having been opened up by the work of 

 Friedrich, Knipping, and Laue, whose first paper appeared about 

 June, 1912 (see vol. xxxv, page 454). h. s. u. 



