Bibliography

Lorenz, Richard. Raumerfüllung und Ionenbeweglichkeit. Leopold Voss. Leipzig, 1922, p. 289.

Richard Lorenz. Degree of Space Filling and Mobility of Ions.

The main task of the book presented here, summarizing the author’s investigations, is the study of the influence of the actual size of ions on their mobility.

The questions touched upon in it are rarely set out even in detailed textbooks and manuals of physical chemistry, despite their theoretical and practical importance.

The first part of the work is devoted to an exposition of methods for obtaining numerical material expressing the “ratio of the space occupied by molecules to the volume of a substance in any given state.”

In the second part the author raises the question of whether the hydrodynamic law of Stokes, derived for solid bodies, may be applied to ions. Einstein drew the author’s attention to this possibility, and Lorenz proves the suitability of this law for the majority of ions, examining various groups of ions: mono- and divalent organic cations, monovalent organic anions, complex inorganic salts, and mono-, di-, and triatomic smaller inorganic ions. The following parts of the book deal with deviations from Stokes’ formula.

The third part contains a summary of all methods for determining limiting molecular electrical conductivity \((\lambda_\infty)\).

The fourth part of the book is devoted to the most recent theories of electrolytic dissociation by P. Hertz (Paul Hertz) and Hosh (Hosch).

In the fifth chapter the author again returns to the applicability of Stokes’ formula to small ions and various solvents.

On the basis of the Stokes–Einstein theory of diffusion, for mercury, molten salts, and various organic liquids as solvents, the coefficient of dissolved substances is determined, and from this the size of the dissolved particles is calculated. Walden’s rule is also used, according to which the product of the limiting electrical conductivity and the coefficient of friction of the solvent is a constant quantity. It turns out that the values calculated according to Stokes–Einstein,

the radii of the ions change with the solvent. They are the smaller, the smaller the molecules of the diffusing substance are in comparison with the molecules of the solvent; thus the correct quantities should be expected for comparatively large molecules.

The last and most important chapter deals with the reasons why the mobility found for small ions does not agree with that calculated theoretically. In a separate table are given, for the alkali metals: the magnitude of the neutral atoms, the actual magnitude of their ions, increasing with atomic weight. In conclusion the author returns to the problem of the dissociation of molten salts, and the reader observes that he has before him a logical development of that work which occupied a considerable part of Lorenz’s life.

The value of the book is increased by the abundant and critically compared literature cited.

In particular, we must be especially grateful to him for the summary of the literature on the amendments, presented in their full historical sequence, to the electrolytic theory of dissociation as regards the anomalies of strong electrolytes (p. 107).

Two specialists took part in the book: van Laar (J. J. van Laar, “Ueber Raumerfüllung u. Zustandsgleichung”) and P. Lertes (P. Lertes, “Ueber den Dipolrotationseffekt bei den elektrischen Flüssigkeiten”).

The book is written in a popular manner; it is intended for the specialist, but for every chemist and physicist working on questions concerning electrical conductivity, the motion of ions, etc., the work of the Frankfurt physical chemist is an indispensable and necessary desk reference book and guide.

M. A. Bloch.