678 Scientific Intelligence. 



Limited). — In preparing this text-book for the use of students in 

 laboratory work, the author has taken into consideration the fact 

 that periods of laboratory work are usually limited to two or 

 three hours, and he has prepared a series of 39 "time-limit exer- 

 cises " to be used in such laboratory periods. He has also incor- 

 porated introductions to several sections of the subject, and in 

 these parts of the book and elsewhere are to be found several 

 important experiments which are suitable when unlimited time is 

 available. Special attention is paid to the subject of accuracy, to 

 the discussion of which an introduction of no less than 35 pages 

 is devoted. The experiments appear to be well chosen and to be 

 clearly and concisely described. h. l. w. 



5. Practical Physical Chemistry : by Alexander Findlay. 

 12mo, pp. 327. London, 1914 (Longmans, Green and Co. Price 

 $1.30 net). — This excellent text-book for the use of students in 

 connection with laboratory experiments has now reached its third 

 edition, after a period of eight years since its first appearance. 

 Several important additions have been made in the present issue, 

 so as to make it more serviceable to the increasingly large num- 

 ber of students who now make a special study of this branch of 

 chemical science. An appendix has also been added, giving 

 tables of some of the more important physical data required in 

 the course that is given. The first chapter deals with the calcu- 

 lation of results and errors, and includes a particularly clear and 

 practical discussion of the use of approximate numbers. The 

 experiments given in the practical part of the book appear to be 

 very well chosen and clearly described. h. l. w. 



6. Molecular Association ; by W. E. S. Turner. 8vo, pp. 

 170. London, 1915 (Longmans, Green and Co. Price $1.40 net). — 

 This is one of the series of monographs on inorganic and physical 

 chemistry, edited by Professor Alexander Findlay. They are of 

 much importance for the use of advanced students and teachers 

 of chemistry. The volume under consideration gives an excellent 

 account of what is known of the molecular state of gases, dis- 

 solved substances and liquids, and it includes an extensive list of 

 references to the literature of the subject. In an appendix is 

 given a long list of results of investigations showing molecular 

 complexity, and here another list of references is supplied. 



h. l. w. 

 1. JC-Pays and Crystal Structure ; by W. H. and W. L. 

 Bragg. Pp. viii, 229, 75 figures, 4 plates. London, 1915 (G. 

 Bell and Sons). — The theoretical work of Laue together with the 

 experimental realization of his ideas by Friedrich and Knipping 

 opened up, about two years ago, a new and very fruitful field of 

 investigation which requires, for its proper understanding, a 

 knowledge both of X-ray phenomena and of crystallography. 

 "As these branches of science have never been linked together 

 before, it is to be expected that many who are interested in the 

 new development find themselves hampered by a tantalising igno- 

 rance of one or other of the essential contributory subjects." " In 



