482 BOOK REVIEWS

pretation are made to appear trivial, although it is conceded that one is handi- capped by not being able to collect a beaker of adsorbed substances for study. One difficulty is hinted at in the example of H on Rh, where it is stated that the true interpretation of the data is in terms of electroreflectance of the substrate rather than the optical properties of a film of adsorbate. In fact, the correct treatment of electroreflectance itself is still a subject of debate. Again, obtaining the film constants by collecting three sets of data is easier said than done: there may be more than one solution, or the accuracy required of the data may be prohibitive. A sobering complication not mentioned at all is the possibility that adsorbed films may be anisotropic.

The book is rounded off by the chapter on photon counting. This refinement in light detection methods has distinct advantages in detection of low intensities, the chapter is valuable for its general treatment of photomultipliers.

M. A. Barrett, Norwegian Technical University, Trondheim

Specific Energies of Galvanic Reactions and Related Thermodynamic data by J. G. Gibson and J. L. Sudworth, Chapman and Hall, London, 1973, xvi+820 pages, £10.00.

The thermodynamics of galvanic cells enables one to obtain from tabula- tions of standard potentials of n electrodes the e.m.f.'s of n(n-1)/2 cells. This and similar facts make the compact tabulation of a vast amount of data possible and as such is one of the great practical uses of thermodynamics.

In the present book the authors have reversed the process, taking the data in its compact form and with the aid of a computer have tabulated e.m.f.'s, temperature coefficients and specific energies of all possible cells constructed of the oxides, sulphides and halides of about fifty metals. This operation involves the minimum of critical selection of data. Reliable collections of data have been used, though it is surprising that one of the main sources, ref. 1, is undated.

The justification for publishing such a book can lie only in the practical usefulness of avoiding some elementary calculations. The data for the 50,000 reactions given here would take 5 man-years to obtain manually and the authors claim that the results are of particular interest to anyone interested in research on novel battery systems. Unfortunately they do not mention whether the prepa- ration of this book led them to the development of a novel battery. It is difficult to avoid the feeling on inspecting this book that an enlargement of the haystack is not the best way to find the needle.

Roger Parsons, University of Bristol