Chemistry and Physics. 501 



fields of investigation are suggested. When the fluorescent vapor 

 is placed in a uniform magnetic field and is excited by plane 

 polarized light there can be no ordinary Zeeman effect. The 

 fluorescent light will be elliptically polarized in the magnetic field 

 and plane polarized in the absence of this field. The eccentricity 

 and the orientation of the major-axis of the ellipses will vary 

 from line to line of the resonance spectrum. In particular, the 

 fundamental line will remain plane polarized while the plane of 

 polarization will be rotated around the magnetic field through a 

 formulated angle. The theory shows very clearly that the inten- 

 sity of the fundamental fluorescent light will decrease and tend 

 toward zero as the strength of the magnetic field is augmented. 

 This phenomenon has been observed and studied by Wood and 

 Riband. In these experiments the angle of rotation is predicted 

 to be 7l° - 565 for a field of 30,000 gauss. The possibility of rota- 

 tion was not suspected at the time of the experimental research 

 and hence numerical data for testing this deduction from the 

 general theory are wanting. For further details reference must 

 be made to the original article. — Phil. Mag., xxxii, p. 265, Sept., 

 1916. h. s. u. 



8. Problems in Physics for Technical Schools, Colleges, and 

 Universities • by William D. Henderson. Pp. viii, 205, with 

 167 figures. New York, 1916 (McGraw-Hill Book Co.). -These 

 exercises are intended to supplement the usual one year's course 

 in general physics and they have been thoroughly tested by the 

 author who causes his students to devote one class-hour a week 

 wholly to the solution of practical problems bearing upon the 

 fundamental principles treated in the lecture room and labora- 

 tory. The problems are numerous (1025), they cover the entire 

 field of elementary physics, and most of them are original. Each 

 set of questions is preceded by a brief statement of the defini- 

 tions and fundamental principles involved and a comparatively 

 large number of illustrative examples are worked out in the text. 

 The data involved are modern and conform to the recommenda- 

 tions and practice of the United States Bureau of Standards. 

 The index is preceded by an appendix containing thirty tables of 

 formulas and physical constants. Answers to the unsolved prob- 

 lems are not given. 



It is difficult for a reviewer, who has not tested the book in 

 the class room, to form a just opinion of the merits of the text. 

 The following impressions, however, acquired by the present 

 writer after having looked over the pages very thoughtfully, may 

 merit recording. With few exceptions the remarks introductory 

 to each group of problems seem very lucid, concise, and accurate. 

 The general plan of the text also seems excellent. With regard 

 to minor details, on the other hand, there is room for revision. 

 For example, the distinction between the Kiientitic meaning of the 

 teiMiis " fluid " and "liquid" is not made clear. In the tables no 

 attention has been paid to percentage accuracy. Thus we find 

 (on page 193): " Pressure of one atmosphere = 76 cm. mercury = 

 30 in. mercury = . . . = 1,012,634 dynes per cm ! = . . . " 



