704 SCIENCE PROGRESS 



The results are tabulated, the measurements of six previous workers being 

 printed in parallel columns for comparison. 



J. R. 



CHEMISTRY 



A Manual of Practical Physical Chemistry. By Francis W. Gray, M.A., 

 D.Sc. [Pp. xvi + 21 1.] (London: Macmillan & Co. Price 4s. 6d. net.) 



This little book is a good example of how difficulties may be surmounted. The 

 difficulties lie in the fact that in some laboratories the time allotted to physical 

 chemistry in a student's course is either too short or too broken to be of much 

 educative value to him. 



In the present work allowance is made for the available time being broken ; 

 and the experiments, numbering nearly forty, are designed to occupy each only 

 from one to a few hours. 



Of course, such a method is bad, as doubtless the author would be one of the 

 first to allow ; but it cannot very well be helped under present conditions, under 

 which the student comes to be fed with knowledge, like a goose being fattened, 

 with the sole object of reaching that lamentable pathological condition, " the 

 degree standard." And any one who tries, as the present author does, to make 

 the best of this bad job, earns the thanks of his fellow-sufferers. 



The Theory of the Solid State. By Prof. Walther Nernst. Based on four 

 lectures delivered at University College, London, in March 191 3. [Pp. viii + 

 104.] (London : University of London Press. Published by Hodder & 

 Stoughton, 1914. Price 2s. 6d. net.) 



THOUGH small in size, this book is one of the most important physico-chemical 

 publications of the year. The problem of the solid state is viewed from the stand- 

 point of thermo-dynamics and the new statistical mechanics, a mode of treatment 

 which has been pursued with extraordinary vigour and success during the last five 

 or six years. Considering the large and varied amount of work expended upon 

 the problem, the variety and complexity of the phenomena and the profound nature 

 of the subject in itself, it is indeed no small tribute to the author's well-known power 

 of exposition to find the whole thing so clearly epitomised in a little over one 

 hundred pages. Not only does the reader obtain a reasonably comprehensive and 

 proportioned view of the whole, but there is at the same time the atmosphere of 

 authoritativeness which always manifests itself when the writer has been himself 

 one of the pioneers in the investigation of the subject which he expounds. 



The book is a reproduction of the four lectures delivered by Prof. Nernst at 

 University College, London, in 191 3, which awakened very considerable interest 

 at the time ; and it is with great pleasure that we welcome the present somewhat 

 belated publication. It must not be thought that we are here given a review of 

 the quantum theory in its entirety, although the quantum theory and the Nernst 

 Heat theorem form the groundwork of the whole treatment. Prof. Nernst has 

 kept closely to the particular subject in hand, and has thus been able within small 

 compass to deal with certain parts of the subject in considerable detail. A notable 

 example is the very excellent account given of the experimental methods worked 

 out in the Berlin laboratory for the determination of specific heats over short 

 temperature ranges down to extremely low temperatures. 



For many years the solid state of matter and the properties of solids had proved 

 a rather unproductive field. The early discovered law of Dulong and Petit 



