66S SCIENCE PROGRESS 



The Properties of Electrically Conducting Systems. Including Electrolytes 

 and Metals. By Charles A. Kraus, Professor of Chemistry in Clark 

 University. [Pp. 415, with 70 figures in the text.] (New York : 

 The Chemical Catalog Co. Inc. Price $4.50.) 



The problem of reducing the experimental material on electrically conducting 

 systems to the form of a readable treatise has been successfully solved by the 

 writer of this book. The enormous expenditure of energy in this field has 

 produced tables of figures, and curves without number, but has not brought 

 out any simplifying assumption comparable in value with that of the simple 

 Arrhenius theory. This has made the task of correlation exceedingly difficult. 



In this book, the author emphasises one of the main causes of the slow 

 rate of development of the theory of electrolytic solutions. The neglect of 

 non-aqueous solutions in the recent theories of ionisation has been a serious 

 handicap to successful effort. Modern theory has largely ignored the 

 astonishing variety of the conductivity curves of electrolytes in non-aqueous 

 solvents, and confined itself to the study of aqueous solutions. The numerous 

 diagrams and tables of data given in the present treatise should serve the 

 useful purpose of directing the attention of chemists to this aspect of the 

 problem. 



Perhaps the most interesting chapters are those which deal with the 

 modern theories of electrolytic solution, and of the ionisation of metals in 

 liquid ammonia. The latter, based chiefly on the work of the author and 

 his collaborators, is especially valuable, since the metals in ammonia give 

 rise to electrical systems intermediate between metallic and electrolytic con- 

 ductors. The part played in these solutions by a new type of anion, com- 

 posed of an electron associated with solvent molecules, is a discovery of the 

 author. The chapter included on the properties of metallic substances 

 serves to illustrate the intermediate character of these solutions. The book, 

 which is intended as a monograph, should not only be used as a work of 

 reference by research workers in this field, but should also be of service to 

 the general reader. For the purpose of the latter, however, since the chapters 

 are so full of material, a summary at the end of each chapter would con- 

 siderably improve its usefulness. It is one of the best of the monographs of 

 the American Chemical Society Series. 



W. E. G. 



Distillation Principles and Processes. By Sydney Young, D.Sc, F.R.S., 

 with the collaboration of E. Briggs, D.S.O., B.Sc, T. Howard 

 Butler, Ph.D., M.Sc, F.I.C., Thos. H. Durrans, M.Sc, F.I.C, 

 F. "R. Henley, M.A., F.I.C, James Kewley, M.A., F.I.C, and 

 Joseph Reilly, D.Sc, F.R.CSc.L, F.I.C. [Pp. xiii + 509, with 

 210 illustrations.] (London : Macmillan & Co., Ltd., 1922. Price 

 40s. net.) 



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The usefulness of a scientific book can often be gauged by the difficulty 

 in obtaining a second-hand copy when it is out of print. Those who pur- 

 chased Prof. Young's Fractional Distillation evidently found it too valuable 

 to part with as, for some time before the appearance of the new work, second- 

 hand copies of the earlier volume were exceptionally rare. Distillation 

 Principles and Processes is, therefore, very welcome, embodying as it does 

 the material of Fractional Distillation, brought up to date with considerable 

 revision and amplification, together with accounts of the application of 

 distillation processes in connection with the manufacture of acetone, alcohol, 

 petroleum products, coal-tar products, gl^'cerine, and essential oils. 



The first part of the book, which deals with the general principles of 

 distillation and follows the arrangement of Prof. Young's earlier book, calls 

 for little detailed criticism. More attention, however, might have been paid 



