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fashion as the electron shell, out of succeeding layers, not of electrons, but of individuals termed "helions" consisting of one electron and two protons (archiom) each. These are not stable in free space but only in the strong force fields within the nucleus. Whatever satisfaction one may feel at the fixed location of the atom constituents is shattered when one comes to the explanation of isotopes and radioactive phenomena. I n the powerful electromagnetic field in the space between nucleus and inner layer of electrons (zwischenraum) still another kind of individual, the neutron, consisting of one electron and one proton, may exist. Of the neutrons there may he any number within wide limits and they are all in rapid and disorganized motion. In their chance collisions are found the causes of radioactive phenomena and in their varying number the cause of isotopy. The most astonishing feature of the author's theory concerns the linking of atoms: a valence or outer shell electron from each atom takes a coaxial position with respect to the other so that the two valence electrons fall in a straight line connecting the two atom nuclei. The author realizes that the electrostatic repulsion of the electrons would seem to make such an arrangement impossible, but he presents arguments to show that in the equilibrium positions this farce would be counterbalanced by attractive forces. The author complains rather bitterly a t the dogmatic manner in which many theorists build on arbitrary assumptions which could never have reality. His own assumptions follow, he claims, naturally and unforced from experimental facts. He gives no details of mathematical analyses t o prove his viewpoints although a t times he expresses his arguments in mathematical language. It is however not beyond the hounds of possibility that the author has committed the same error he denounces in others. Some of his assumptions seem to be not only arbitrary but unreasonable and a careful reading of his
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arguments does little to counteract that impression. The value of a theory of the structure of matter rests in its usefulness in classifying facts of observation and predicting new facts and the more diverse the classes of facts thus brought together the more valuable the theory. The author's unsurpassed acquaintance with such properties of substances as magnetic susceptibility, dielectric constant, frequencies of emitted and absorbed light, etc., place him in a position t o measure the serviceability of a theory with respect to such facts. He likewise offers quite a wealth of chemical fact in support of the adequacy of his theory. Unfortunately, however, very little is first-hand fact of observation. I t is rather the conclusion from observation stated in the language of theories of doubtful comprehensiveness. He speaks of valence and changes in valence with assurance, perhaps not realizing that no chemist has ever formulated a satisfactory definition of valence. The value of this very comprehensive and painstaking work of the author lies in showing the fallacies of some of the current theories and in its suggestiveness as t o starting points in building a completely serviceable theory. Some of the baffling physical properties of matter are made in some respects more comprehensible by the author's theory but the chaotic facts of chemistry are by no means brought as nearly into an orderly system by it as by other of the modern theories. ARTHURA. BLANCHARD Vestiges of Pre-Metric Weights and Measures Persisting in Metric-System Europe, 1926-1927. ARTHURE. KENNBLLY, Professor of Electrical Engineering a t Harvard University. The Mamillan Co., New York City, 1928. xvi 189 pp. 9.5 X 14.5 cm. $2.50.
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The book is the result of a research with the aid of the Bureau of International Research of Harvard University and Radcliffe College. Professor Kennelly ex-
plains his method of investigation visiting nine different countries. The author has successfully lifted the subject above the plane of controversy t o that of a statistical inquiry which is delightful in contrast t o those writers opposed to the Metric System. He barely refers to those who would tell us that "the Metric System is a will-&the wisp which the nations of the world are always chasing but never catching," but be gives unimpeachable evidence permitting one to estimate what should occur when a nation adopts the Metric System. I n the first place, a certain interval, usually two or three years, was allowed by law before the change was ordained to go into effect. I n the cities and progressive communities the change was made in a few weeks by the bulk of the population. I n remote villages and among the less progressive the change occurred more slowly. Similarly, in manufacturing, the change was made more slowly. No machinery w s discarded, but the sizes of manufactured articles were numerically altered to conform to the new system. Old drawings were left unchanged until in the course of time they had to be replaced. Just as the vermiform appendix is a vestigial reminder of the paunch of the ruminants so the apparently arbitrary sizes sometimes suggest systems which antedate the Metric System. Not many people, for example, know the origin of the shoe and collar sizes which they employ. Many of us know that the livre and pfund are used in France and Germany being what Prof. Kennelly calls Metricised Units. He says, "Although a constant watch was kept for old standard weights or standard measures in Italy, none but Metric standards were ever found except in museums and antiquity shops." It was much the same over all of Europe visited. I n Holland occasionally one asks for an "ell" of something, but no ell stick was found, the ell being made a sub-netricised unit of 70 cm. which will
before long be unused. The non-metric unit of interest is the Rhineland-inch used in Germany in measure of boards. The English system appears in the measure of textiles, leather, shoes, and printing but the use is decreasing and often as an arbitrary designation rather than a measure. This result since the war presents a changing condition as regards export trade from this country. Many of the ancient units of Europe exist in name only. Street vendors cry "6 liards the bunch," despite the fact that for a hundred years nb one has known what a liard is. The use of the terms liard, livre, and pfund are no more proof that Europe is non-metric than the existence of the Hotel Powhatan is a proof that Washington is inhabited by American Indians. Rummaging around Europe looking for ancient measures must have afforded much amusement. For example, Professor Kennelly tells us that George Washington was not born on February 22 hut on Februaty 11, 1732. The old style calendar was falling hopelessly behind and was therefore moved up eleven days in 1752, which was 170 years after the change had been made by Central and Western Europe. EUGENEC. BINGHAM Radicals in Chemistry, Past and Present. MOSES GOMBERG.Columbia University Press, New York City, 1928. 23 pp. 6 X 9 cm. $0.50. This pamphlet contains the tent of the Chandler Lecture delivered December 16, 1927, in Havemeyer Hall, Columbia University by Professor Gomberg, on which occasion the lecturer was awarded the Chandler gold medal for his outstanding work on Tri-valent Carbon and on Free Radicals. It contains a brief but inclusive survey of the history of free radicals, emphasizing chiefly those aspects which are of general interest. M. W. G.
