Bibliography

M. KNOLL, F. OLLENDORFF and R. ROMPE, Gasentladungstabellen. Formulas and curves for the physics and technology of electrons and ions. With the collaboration of A. Roggendorf, B. Springer, 1935, X, 171, I, p. 196, illus. Mk. 29.

M. KNOLL, F. OLLENDORFF and R. ROMPE, Tables on Gas Discharge. Tables, formulas and curves as applied to the physics and technology of electrons and ions.

The authors set themselves the aim of compiling a handbook of formulas, curves of experimental data, and mathematical tables that would satisfy the needs of the physicist-researcher and the physicist-engineer working in the field of electronics and gas discharge. Such a handbook, making it possible to save a large amount of time spent consulting reference books and original works, is, of course, highly desirable. But, by facilitating work, it must at the same time provide the reader with all the threads for a detailed acquaintance with the literary material and for checking, when necessary, the conditions under which particular experimental data were obtained, as well as the assumptions on which the theoretical conclusions and formulas are based. This requirement has been met by the authors only in part. Many experimental data are given with references not to the original works, but to the “Handbuch der Physik” or to Engel and Steenbeck’s little book “Gasentladungen,” whose influence on the authors is very strongly felt. Thus, in a considerable part of the material is presented after a double processing, and there remains the necessity of using the Handbuch or the above-mentioned book as an intermediate stage for the desired clarification of the data. As regards theoretical data, matters are still worse. There is neither a derivation of the formulas (which, of course, should have no place in a handbook), nor any indication of where, when, and by whom they were derived, or by whom and where the given theory was developed. If the matter concerned only generally known formulas and theories, which the handbook merely has to recall, then failure to mention the author of the theory would still be acceptable. But many formulas in the given book are new, and moreover simplified, and apparently based on some simplified methods of calculation. In order to use them it is necessary to be able to judge at least the degree of approximation and the formulation of the question that led to them.

In some cases the necessary data can apparently be found in the book by Engel and Steenbeck, to which the authors do not refer. With respect to others there is only the authors’ statement in the preface: “in many cases we found it necessary to include the results of our own calculations, the theoretical justification of which will partly be given later elsewhere.” We repeat: such an approach is unacceptable for a handbook, and therefore the theoretical material of the book cannot be used with complete confidence.

As regards the selection and arrangement of the material, the already different levels reached by experimental research in the individual sections of the field of physics presented in the book lead to the fact that these sections cannot be presented uniformly. But the authors have further increased this unevenness. Thus, with regard to secondary electron emission and emission by positive ions (coefficient \(\gamma\)), with all desire it would not have been possible to cite many well-founded data, but, on—

for example, the section on the work function of electrons from various substances should have been presented more fully. Here one could not limit oneself to indicating the minimal and maximal observed values (p. 75), which differ greatly from one another; it was necessary to give them a critical evaluation and indicate the most probable values. Another example of insufficiently careful presentation is the paragraph on the classification of atomic terms (p. 19): for a reader who knows the foundations of this classification, the half-page devoted to this question gives nothing, tells him nothing substantial, and does not acquaint him with the question. In the following paragraph, for a larger number of cases, schemes of spectral terms and spectral lines should have been given, especially for neon, helium, and argon, with which almost everyone working in the field of gas discharge has to deal. In the chapter on the ignition potential of a gas discharge (p. 84), the question of the dependence of this potential on admixtures to the principal gas is not reflected at all. And in general there is very little experimental material here, apart from the breakdown of atmospheric air. Conversely, Chapter V, “Technique of high vacuum,” in this reference book could quite readily have been omitted in favor of developing other sections. Let us also point to one very significant omission: in listing the critical potentials and atomic terms of helium, neon, argon, etc. (p. 59), metastable states are not indicated at all. Moreover, the book does not mention metastable atoms at all, although they play an extremely important role in gas discharges. They can be found, so to speak, in implicit form and very incompletely presented only in Table g 22, p. 62.

Any reference book giving numerical values must be very carefully checked. Repetitions in it are undesirable, and different numerical indications in different places for one and the same quantity are inadmissible without corresponding explanations. The authors nevertheless contrived to sin against this obvious truth. Certain data relating to the electron are given both in Chapter I, “Physics of individual particles,” and in Chapter VII, “Systems of units and general constants.” Thus, for the ratio of the electron charge to the mass, on p. 4 the value is given as

\[ 0.528 \cdot 10^{18}\left[\frac{ESE}{g}\right], \]

whereas on p. 155 it is

\[ 0.530 \cdot 10^{18}\left[\frac{ESE}{g}\right]\left(\text{in }\left[\frac{Clb}{g}\right]\text{ the figures are the same}\right). \]

In a very detailed table of ionization potentials (p. 53), presented for the first time in such complete form, an unnoted misprint has crept into its proper place: “Ru” instead of “Ra.” This, of course, is unimportant in itself, since the ordinal number of the element is in the table, but in connection with what has been said this leads one to the thought of insufficient care in reviewing the letter designations and figures, which, of course, reduces the reliability of the use of the reference book.

Since the book under review is the first attempt to provide a reference book in this field, and since it contains a rather large amount of varied material, despite all the substantial shortcomings indicated above it will undoubtedly be a useful aid for persons working in the field of electronics and gas discharges, at least for the near future, until it has time to become obsolete because of the rapid development of this field.

N. Kaptsov

PERCY WILLIAMS BRIDGMAN. The Thermodynamics of electrical phenomena in metals. N. Y., Mc Millan, 1934, 206 p., diagr., bibl. Doll. 3.75.

P. W. BRIDGMAN. Thermodynamics of electrical phenomena in metals.

Professor Bridgman of Harvard University is one of the most prominent American physicists. Especially well known are the extensive investigations he carried out at the beginning of the present century on the thermodynamic properties of