Chemistry and Physics. 457 



clear idea of the contents of this book ma}^ be obtained from the 

 following quotation : " In this small volume an attempt has been 

 made to deal with the most important facts of the science of 

 Radioactivity in a manner simple enough to be understood by 

 readers with a very elementary knowledge of Physics and Chem- 

 istry." On the whole, the treatment of the subject is reliable 

 but rather one-sided, for, relatively too much space is devoted to 

 the work of Sir William Ramsay. A typical illustration of this 

 bias is afforded by Chapter VII which is entitled "The Transmu- 

 tation of Elements," and which should be read with due caution 

 and reservation. Also, the emanation from radium is called 

 " niton" almost exclusively. The volume contains four useful 

 appendices but no index. h. s. it. 



6. Spectroscopy ; by E. C. C. Baly. Second edition. Pp. xiv, 

 687, 180 figures and 3 plates. London, 1912 (Longmans, Green 

 and Co.). — Since the first edition (1905) of this book was the best 

 text on the subject in the English language, and since numerous 

 important spectroscopic investigations have been carried out 

 during the past seven years, the new edition will be welcomed 

 by all who are interested in this highly specialized branch of 

 science. In order to save space, Chapter XYII of the earlier 

 issue, which described Rowland's ruling engines, has been omitted. 

 Also, other matters of relatively minor general importance have 

 either been left out entirely or discussed very briefly. Neverthe- 

 less, the text proper has increased from 550 to 649 pages. 



More specifically, the first nine chapters have only been 

 changed by the addition of such material as brings them down 

 to date. Chapter X has had its title and content altered from 

 " The Efficiency of the Spectroscope " to " The Practical Resolv- 

 ing Power of the Spectroscope." In other words, Wadsworth's 

 theoretical investigations have been omitted and replaced by 

 Schuster's more useful results. Chapter XII, formerly on " The 

 Production of Spectra," is now entitled " Methods of Illumina- 

 tion," and the articles on absorption spectra have been elaborated 

 and collected in a new chapter, (XIV). In like manner, a 

 separate chapter has been devoted to fluorescence and phos- 

 phorescence, (XIII). In the new edition, Chapters XVI, 

 XVII, and XVIII have been very appreciably increased in 

 scope, and excellent bibliographical lists have been appended 

 to the last two of these chapters. It is clear therefore, 

 that as far as the subject matter is concerned, the text has been 

 markedly improved and its practical value as a reference book 

 has been greatly increased. Unfortunately, in matters of detail, 

 such as proof-reading and accuracy of statement, much room for 

 improvement remains. h. s. u. 



