REVIEWS 695 



Whether the author's views on disputed questions will all prove to be correct 

 time alone will show. On some points he certainly seems to form a judgment 

 rather lightly ; but as a whole the book is unquestionably well worthy the attention 

 of those who wish a summary of the present state of seismic knowledge and an 

 indication of the principal problems remaining to be solved. Some of the illus- 

 trations are excellent, especially those showing records from Milne seismographs 

 and those illustrating Galitzin's experiments ; but there are a few — e.g. figs. 3, 4, 7, 

 10, 11, and 15 — reduced apparently from large diagrams or maps, in which details 

 are so minute as merely to irritate the eye. Some of the chapters show signs of 

 somewhat hasty revision. The devotion of Prof. Milne to the subject is worthy of 

 all praise, and the author's references to the results of his labours on p. 187 are 

 well deserved ; but when the reader finds practically the same remarks repeated 

 on p. 198 he instinctively begins to think of Aristides. In a few cases — e.g. in the 

 tables on pp. 203 and 215 — the exact nature of the data collected and the units 

 employed might with advantage have been more clearly stated. In other cases — 

 e.g. on pp. 165 and 167 — in the matter of wave velocities, the cart seems to get 

 a little in advance of the horse. Few actual slips have been noticed. On p. 96 

 there seems a confusion between North and South Pacific. There is obviously 

 a misprint in the value of Poisson's ratio on p. 165 for " Lily Lake" granite. In 

 several cases — e.g. p. 78 — quantities are neglected or described as inappreciable 

 when they are only relatively small, and not, strictly speaking, negligible. A 

 further criticism that is not unlikely to be made is that the price seems high for 

 a book of the size. It only remains to add that there is a table of contents, an 

 enumeration of the illustrations, and an index, so that reference to specific points 

 should be easy. 



C. Chree. 



General Chemistry for Schools and Colleges. By Alexander Smith. 

 [Pp. xiv. + 530 with 65 figures.] (George Bell & Sons, 1908. 6s. 6d. net.) 



Of the making of text-books of chemistry there is no end, but in the com- 

 pilation of the present treatise the author has certainly not travelled along the 

 well-worn track. 



In four introductory chapters a few simple experiments are discussed with 

 the object of defining what are the characteristics of chemical changes as distinct 

 from those of other natural phenomena. A detailed consideration of these typical 

 reactions shows that there are six characteristics of chemical change, several 

 of which can only be appreciated by quantitative experiments. The author is 

 thus led at a very early stage to emphasise the importance of exact measure- 

 ments as the only safe guide to the elucidation of chemical changes. 



A few atomic weights are taken for granted in the third chapter in order that 

 symbols, formulas, and equations may be explained ; after which follow several 

 chapters on general and descriptive chemistry. In Chap. XII. the author reverts 

 to and discusses more fully the more difficult parts of the subject in connection 

 with the determination of atomic and molecular weights. 



Although the intermingling of chapters on descriptive chemistry with those 

 on fundamental principles may have the effect of imparting variety to the student's 

 reading, yet in some instances the arrangement of topics is somewhat arbitrary. 

 For example, a chapter on chemical equilibrium is interposed between one on the 

 halogen family and another on the oxides and oxygen acids of the halogens. 

 The chapter on ozone and hydrogen peroxide is sandwiched between chapters on 



