NEW BOOKS Kolloidik. Eine Einfuhrung i n die Probleme der modernen Kolloidzoissenschaft. By A. v. B I J Z ~ G H323 . pp. Leipaig: Th. Steinkopff, 1936. Price: unbound, 15 RM; bound, 16.50 RM. The portmanteau word “Kolloidik” means colloid chemistry and colloid physics; in the language of a century ago, the natural philosophy of colloids. The author is evidently of a philosophical turn of mind, for the whole treatment of the subject is subordinated t o his classification of matter according to degree of subdivision primarily and to morphology secondarily. The systematics may become a little tedious t o English readers; experimental facts are mentioned strictly in their proper place according t o the system of the book. Too often, facts are touched upon only incidentally in the development of the system of classification, and sometimes selection is rather oddly made; thus as functions of dispersity, under the heading “physical,” are included transparency, hardness, photoelectric properties (of thin metallic films, which are apparently considered geod instances of the effect of thickness on an otherwise homogeneous state of matter, an opinion which the reviewer certainly does not share), and catalysis; as “physicochemical” are mentioned some cases where the ordinary laws of solution or of electrolysis appear, a t first sight, not to be obeyed by colloidal systems; and under “chemical,” Smekal’s theory of the mosaic structure of crystals. Later on in the book the author comes to rather closer grips with the results of experimental research; among many other things dealt with are the results of x-ray investigations into the structure of natural compounds of high molecular weight, liquid crystals, surface films, electrical double layers, the use of electron beams for studying surfaces, sedimentation volumes, theories of adsorption, peptization, swelling, coagulation, etc. But the treatment is rarely sufficiently profound or exact to give the reader a well-balanced idea of the essentials of the phenomena and of their explanation; and literature references are not sufficiently numerous or up-todate to guide one who wants to master the original literature quickly. It may be that the author has been seriously handicapped by his desire to treat everything logically and systematically from the standpoint of dimensions and manner of aggregation. These are not the fundamental properties of matter; they are sometimes very important and dominate the phenomena, but often they are overshadowed by specific chemical properties, which indeed control them. A natural philosophy of that vast miscellany of phenomena loosely classified as colloids must not forget this; nor indeed is i t generally profitable to treat experimental research as a mere handmaid t o a subjective scheme of things. The book is tolerably w l l conceived, but it lacks thoroughness, and shows little originality. N. K. ADAM.
Reports on Progress i n Physics. Published by the Physical Society. Volume 11. 25 x 17 cm.; iv 371 pages. London: The Physical Society, 1936. Price to nonFellows: 21 s. net. The second volume of this new venture resembles the first in being printed on excellent paper, with a dignified format and good binding, and in containing a set of reviews written by experts on the theoretical and applied sides, which provides material of the highest interest to physical chemists. The sections are (neglecting 933
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