REVIEWS 157 



The contents of the volume do not call for detailed description : they have 

 been selected with care, and the treatment has been adapted for those who have 

 but little mathematical knowledge. A detailed account of the eye is included : the 

 general theory of the symmetrical optical instrument is explained, and the theory 

 of chromatic and spherical aberrations are briefly treated. An account is also 

 also given of Von Seidel's formulas for the five spherical aberrations in the case of 

 a system of infinitely thin lenses. An account of central collineation of object 

 and image spaces has been wisely included. Numerous examples for the student 

 to work are given at the end of each chapter. Attention should be drawn to the 

 fact that figures 31 and 32 have been entirely omitted. 



The author is an experienced teacher, and we hope that the volume will succeed 

 in stimulating interest in the study of geometrical optics, and form a ground-work 

 from which the student can proceed to the study of more advanced treatises. 



H. S. J. 



CHEMISTRY 



A System of Physical Chemistry. By William C. McC. Lewis, M.A., D.Sc, 



Brunner Professor of Physical Chemistry in the University of Liverpool. 



(Textbooks of Physical Chemistry. Edited by Sir W. Ramsay.) (London : 



Longmans, Green & Co.) 

 Vol. I. Kinetic Theory. [Pp. xii + 494, with diagrams.] (London, 191 8. 



Price 1 5 s. net.) 

 Vol. II. Thermodynamics. [Pp. vi -I- 403, with diagrams.] (London, 1919. 



Price 1 5 j. net.) 

 Vol. III. Quant inn Theory. [Pp. viii + 209, with diagrams, and 2 Appendices 



by James Rice, M.A., Lecturer in Physics in the University of Liverpool.] 



(London, 1919. Price ys. 6d. net.) 



The first two-volume edition of this work was reviewed in these pages in January 

 1917. The present edition differs chiefly in the addition of a third volume on the 

 Quantum Theory. Vol. I now contains certain fresh chapters dealing with 

 X-rays and Crystal Structure, the Colloidal State, Theories of Catalysis, Displace- 

 ment Effect, the Mechanism of Surface Effects, and a brief discussion of Entropy; 

 whilst in Vol. II space has been found for chapters on Osmotic Pressure, the 

 Modern Theory of Dilute Solutions, and the Theory of Vegetable Tanning. 



Vol. Ill deals, of course, primarily with Planck's Quantum Theory and the 

 various researches and theories connected therewith, notably those of Einstein, 

 Nernst, Lindemann, Bohr, and Moseley. 



There are three Appendices, of which the first two are by Mr. J. Rice, and are 

 concerned respectively with " Maxwell's Distribution Law and the Principle of 

 Equipartition of Energy" and "Foundations of the Quantum Theory," the third 

 Appendix containing a summary of Kriiger's papers on the Theory of Gyroscopic 

 Molecules. 



Whilst it is evidently desirable that English readers should have an authentic 

 account of modern development in the field of subatomic phenomena and radio- 

 activity and all which deals with that borderland of science lying between chemistry 

 and physics, one is seriously tempted to inquire whether the third volume has not 

 overstepped the limits of chemistry altogether, or, at most, whether it would not 

 be more correct to include it in a " System of Chemical Physics " ! 



Still, whichever way one chooses to take it, Prof. Lewis's trio will doubtless find 

 a large and appreciative audience of chemists and physicists even though the 



