Chemistry and Physics. 379 



graph on argon,* the experimental process consisting essentially 

 in comparing the wave-length of sound in each rare gas with the 

 wave-length in air for the same frequency, by Kundt's method. 

 The mean values of the wave-lengths for air, neon, krypton and 

 xenon at 19° C. were found to be 5*584 cra , 7*220 cm , 3*626 cm and 

 2*864 cm respectively. Taking the densities of these gases, in the 

 order named, as 14*479, 10*10, 41*46 and 65*11, and assuming y 

 equal to 1*408 for air, it follows that the ratio of the specific 

 heats of neon, krypton and xenon equals respectively 1*642, 1*689 

 and 1'666. Ramsay concludes : — "These numbers approximate 

 within the limits of experimental error to the theoretical ratio 

 1*667, and it therefore follows that neon, krypton, and xenon, 

 like helium and argon, must be regarded as monatomic." " Their 

 molecular and their atomic weights are identical." — Proceedings 

 Roy. Soc, lxxxvi, p. 100, Jan., 1912. h. s. u. 



9. Modem Microscopy ; by M. I. Cross and Martin J. Cole. 

 Fourth edition, revised and enlarged. Pp. xvii, 325, with 113 

 figures and 6 plates. Chicago, 1912 (Chicago Medical Book Co.). 

 — "In the preparation of this new edition, the original intention 

 that it should be for beginners and students has been steadily 

 kept in view." The volume is divided into three parts, of which 

 the first deals with microscopes and auxiliary apparatus such as 

 ray-filters, artificial sources of light, text-books, etc. Care is 

 taken to define and explain the significance of many optical 

 terms, for example, aplanatism, chromatic over-correction, spheri- 

 cal aberration, etc. In short, this Part, which comprises 136 

 pages, will enable an intelligent beginner to purchase wisely and 

 to subsequently use and care for his apparatus to best advantage. 



Part II, of 82 pages, is devoted to staining, section cutting 

 and, in a word, to the general preparation of microscopic objects. 



Part III, covering 100 pages, is entirely new, and it is divided 

 into seven chapters, each of which was written by a specialist. 

 It gives information on many subjects in which amateur micro- 

 scopists in particular are interested, such as : interference figures 

 of arragonite, larvae of hydrachnid parasites, bacillus anthracis, 

 etc. The six plates belong to this Part and they are clear, beau- 

 tiful reproductions of the original negatives. In conclusion, the 

 subject is presented in such an attractive and elegant manner 

 that the book deserves to win many converts to the branch of 

 science with which it deals. h. s. tj. 



10. Laboratory Problems in Physics ; by Franklin T. Jones 

 and Robert R. Tatnall. Pp. ix, 81. New York, 1912 (The 

 Macmillan Co.).— This book is in part a liberal revision of Crew 

 and Tatnall's " Laboratory Manual of Physics" and, with regard 

 to its contents, the authors say : " While these exercises may be 

 used in connection with any text-book, the order adopted is that 

 of Crew and Jones's * Elements of Physics.'" The 72 experi- 

 ments suggested are intentionally of an elementary nature, they 



*Phil. Trans., A, 1895, Vol. 186, Part I, p. 228. 



