REVIEWS 493 



It is unsuitable for students, since it is of far too specialised a character, and 

 the principles underlying the phase theory can be much better appreciated 

 by a consideration of simpler cases, in which the purely arbitrary geometrical 

 difficulties of representation are less formidable and distracting. The 

 author, on the other hand, explicitly states that his book is not a work of 

 reference ; the absence of an index, and of any method of division of the 

 subjects of the text, which runs from one topic to another without obvious 

 break, confirm this decision. The general reader will find that a study of 

 the book calls for considerable concentration. The long digressions on 

 geometrical representation, even with the aid of the diagrams, are not easy 

 to visualise. This, however, is the case with all advanced accounts of the 

 phase theory, and Dr. Clibbens has succeeded in making the subject much 

 clearer than is usually the case. The collection of the results of a large 

 mass of scattered information, and its treatment on a uniform plan, will also 

 hghten the work of numerous technical chemists who are employed on 

 investigations of the kind described. Some of those who, like the reviewer, 

 have had an opportunity of seeing the results of a careful application of the 

 phase theory in the hands of IVIr. Freeth (who contributes an introduction 

 to the book) will wish to study the methods for themselves. Dr. Clibbens' 

 book should prove a useful introduction to this field of applied physical 

 chemistry. J. R. P. 



Ozone. By E. K. Rideal, M.B.E., M.A., Ph.D., Professor of Physical 

 Chemistry, University of Illinois. A treatise of Electrochemistry, 

 Edited by Bertram Blount, F.I.C. [Pp. x + 198.] (London : 

 Constable & Co., 1920. Price 12s. net.) 



The chief objection that may be raised against Prof. Rideal's work is 

 that perhaps too much attention is paid to theory and that the practical side 

 is therefore relatively neglected, as 142 pages are devoted to theoretical 

 consideration, whilst the applications are dealt with somewhat shortly in 34 

 pages. 



Yet perhaps, after all, there is much to be said for this arrangement as 

 ozone has hardly attained to the importance in industry that might be 

 expected from so active and clean an oxidising agent. 



The problem is chiefly one of price, and if only some new and more efficient 

 process could be discovered for preparing ozone, or some method for increasing 

 the efficiency of existing processes, the use of ozone would increase considerably. 



Even as it is, ozone is used for such diverse purposes as sterilising water, 

 treating wounds, for bleaching and for the production of vaniUin, heliotropin 

 (the formulae on p. 166 are incorrect, by the way), and for purifying air, though 

 in this connection Dr. Rideal points out, however, that the value of ozone is 

 open to doubt and that the immunity of motor-drivers on the London tubes 

 during the 'flue epidemic was probably to be attributed to the uniformity of 

 temperature rather than to any specific action of the ozone in the air ! 



The author has done a useful service in coUecting together much scattered 

 information on the subject and the book will be of great assistance to those 

 interested in the theory and the applications of the gas. 



F. A. Mason. 



The Carbohydrates and Alcohol. By Samuel Rideal, D.Sc, F.LC, and 



Associates. [Pp. xv + 216 with 11 Figures.] (London : Bailliere, 

 Tindall & Cox, 1920. Price 12s. 6d. net.) 



In this, the latest volume of the series of books on Industrial Chemistry pre- 

 pared under the general editorship of Dr. Samuel Rideal, a concise account 

 is given of the technology of the industrially important carbohydrates and of 

 their fermentation products. 



