294
NETT' BOOKS
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Temperature Control. By A. J *SLEY. 5: x 8+ in.; viii 127 pp.; 81 figures. London: Chapman and Hall, Ltd., 1942. Price: 13s. 6d. There is need for a compact and practical treatise on temperature control, but i t cannot be said that this want is supplied by the present book. The descriptions are u o t clear, the figures are often unsatisfactory (one is printed upside down), and the lettering on the figures often does not correspond with that in the text. S o indication is given of the degree of temperature control possible v i t h the various types of apparatus. The spelling is often weak and there are some disturbing blunders, as when the boiling point of sulfur is given as its melting point and when aniline is recommended as a non-inflammable liquid. Although there is some useful information in the book it is on the whole a disappointing performance a n d in the reviwer's opinion is not likely t o be of much service in a scientific laboratory unless the user has already a good knowledge of the general methods of temperature control. Particular difficulties encountered x i t h various types of apparatus and the best means of overcoming them are usually not mentioned, and the reader who expects t o firid such useful information will generally be disappointed. The construction of one or two very simple pieces of apparatus is described in unnecessary detail and the general impression received is that the author is not himself familiar rritli most of the apparatus he a t tempts t o describe. J. R . PARTIKGTON. Hydrogen I o n s . Their Determination and Importance in Pure and Applied Chemistry. By H. T. S. BRITTOX.(Monographs on Applied Chemistry, edited by E. H. Tripp). Third edition. Two volumes. 54 x S i in.; xix 420 pp. , 86 figures; xix 443 pp., 165 figures. London: Chapman a n d Hall, Ltd., 1942. Price: 36 s . each volume. The third edition of this well-known work has several new chapters added and now appears in two volumes. The first volume deals with the theory and methods of determining hydrogen-ion concentration, and the second chiefly with the applications in pure and a p plied chemistry. The chapter on the modern theory of electrolytes in the first volume has been largely rewritten and is a n improvement on that in the second edition, but the activity concept has not been much used in the remaining text, the author basing electrode potentials and pH values on a hydrogen electrode standardized in terms of hydrogen-ion concentration a s determined by conductivity ratio. Although he points out t h a t most of the earlier buffer standards are based on this procedure, i t can hardly be regarded as in step with modern work. I n practice, the actual standard is some valne assigned to a calomel or other secondary electrode, and as the author states clearly what values he assumes for this, his own figures are free from ambiguity. Whether other authors whose values he quotes have adopted the same standard is not clear. There are new chapters on the modern views of acids and bases, the dissociation constants of polybasic acids, and on redox potentials and indicators. The bearing of the subject on analytical chemistry receives consideration, especially in the second volume. A feature of the book is the very practical character of the treatment, the apparatus and manipulation being fully described and tables of numerical data given. This makes it likely to be very useful in the laboratory, and as the field of applications covered is very large, i t should make a wide appeal in this direction. As it contains a large amount of useful information and d a t a , with literature references, i t should find a place in every laboratory where work on hydrogen ions is carried out. It is well printed on good paper. J. R. PARTISGTOK,
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The Theory of Emulsions and their Technical Treatment. By WILLIAXCLAYTON.4th edition. 10 x in.; vii 4'32 pp. London: J. and A. Churchill, Ltd., 1942. Price: 42 s . An enormous capital is involved in the industrial application of emulsions. This fact, together with the unsatisfactory scientific approach t o the study of the phenomenon of emulsions, which until very recently has taken place, has led industry to formulate a series of cookbook recipes of semi-secret nature, built up by empirical practice. The nature and
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