Bibliography

Prof. Ya. M. Katushev and Docent V. I. Sheberstov. Fundamentals of the Theory of Photographic Processes. 396 pp. State Publishing House of Light Industry. Moscow, 1944. Price 18 rubles.

The authors intend their book as a textbook for the course “Photography and the Chemistry of Photographic Processes” in the technological faculties of polygraphic institutes. However, their book will have a broader circulation. The significance of photography not only as an art, but also as a remarkable instrument of scientific research, is well known. In particular, physicists working in the most varied fields of their science make extensive use of the photographic method. At the same time, one often encounters the fact that researchers who use photographic plates in their work do not know sufficiently well the properties and particular features of photographic processes, i.e., are little acquainted with the scientific foundations of photography. One reason for this is, in part, the lack of manuals that take into account the needs not of the worker in the field of scientific photography. From this point of view, the appearance of the book under review by Prof. Katushev and Docent Sheberstov, which gives a clear exposition of the subject in a moderate volume, should be welcomed.

The contents of the book are as follows. A rather extensive introduction (63 pp., chapters I and II) is devoted to the general foundations of photochemistry. Here the properties of radiant energy and the nature of the chemical action of light are briefly considered. Immediately adjoining this introduction is Part I, in which the mechanism of the photochemical process in photographic layers with silver halide salts is considered specifically (chapter III), as are the photographic emulsion (chapters IV and V), development and fixing (chapters VI and VII), including the formulation and special cases of development (fine-grain development, desensitization). Part II—the most extensive (153 pp.)—is devoted mainly to the sensitometry of negative and positive processes (including spectral sensitometry). Finally, in the last two parts of the book, III and IV, special photographic methods are considered (the wet collodion method, light-sensitive photographic layers without silver salts).

From this brief survey of the contents it is clear that the book under review, although it does not exhaust the subject, provides a sufficient amount of information and therefore will probably be widely circulated—in particular in physics laboratories.

Of course, there is no such book in which a specialist would not notice various shortcomings or errors. To the reviewer, as a physicist, the defects in the exposition of general photochemical and physical questions are most noticeable. As a fundamental objection it should be pointed out that, having devoted a considerable part of their book to the general foundations of photochemistry, the authors have completely set aside consideration of the question of the mechanism of the elementary photochemical process in gases and in solutions. The principle

Bibliography

The Franck–Condon principle, which plays such an important role in modern photochemistry, is not even mentioned. Chapter II—“Actions of Absorbed Light”—in its content, principles, and even phraseology is generally at the level of 1920 and, consequently, is more than 25 years out of date. The indication that the questions considered in this chapter serve as an introduction cannot serve as a justification. The reviewer was also dissatisfied with the presentation of the question, important for photography, of the scattering of light.

The authors’ terminology does not always correspond to that established among physicists. It is absolutely inadmissible and simply a gross error to use the term “metastable state” to denote any excited stationary state, as the authors do twice on p. 37. Not everything is in order with the dimension of Planck’s constant \(h\): on p. 13 the authors measure it in ergs (!), on p. 14 in \(\text{erg}\cdot\text{sec}\), on p. 35 in \(\text{erg}/\text{sec}\), and on the same p. 35 they write, in black and white, about the numerical value of \(h\) “in absolute units of work (ergs)”! Finally, one cannot fail to note the astonishingly absurd (may the authors forgive us for this sharpness) notation on pp. 17 and 18 and in Fig. 2 for the thickness of an elementary layer by \(dd\) (let us explain that the first \(d\) in this notation is the symbol of differentiation, while the second is the letter denoting the total thickness of the layer). On p. 18, with this notation, they write the following differential equation: \(dJ/J=-kdd\) and, carrying out, so to speak, an “indefinite-definite” integration, obtain \(\ln J=-k'd+C\). Truly, it would have been better to do without such “mathematics” and simply write the law of absorption in integral form.

Despite these and other defects, the book, as has already been said, is useful, and the authors, we shall hope, will correct its shortcomings in the next edition.

E. Shpol’skii