In Memory of N. K. Shchodro

Obituary1

On March 12, 1940, after a prolonged and serious illness, Nikolai Ksaverievich Shchodro, Corresponding Member of the Academy of Sciences of the USSR, passed away.

N. K. Shchodro was born on May 6, 1883, in the city of Tashkent, into the family of an agronomist. N. K. received his secondary education in Smolensk, at a gymnasium, which he completed in 1903. In the same year he entered the Physics and Mathematics Faculty of Moscow University, graduating in 1908 with a diploma of the first degree. After graduating from the university, N. K. Shchodro was retained at the Department of Physics under Prof. P. N. Lebedev.

N. K. did his first scientific work in physics in P. N. Lebedev’s laboratory while still in his final year at the university. Pyotr Nikolaevich Lebedev highly valued N. K. Shchodro, seeing in him an outstanding experimenter. N. K. Shchodro’s investigation, connected with the general direction of the work of P. N. Lebedev’s laboratory, was devoted to the production of Hertz waves by means of Duddell’s arc of undamped oscillations. This work, published in the Journal of the Russian Physico-Chemical Society and in Annalen der Physik in 1908, was the first study in which electromagnetic waves were obtained by the method of undamped oscillations. This work is cited in the British encyclopedia by J. J. Thomson, who gave N. K. Shchodro’s work a high appraisal.

After completing his first work with P. N. Lebedev, N. K. Shchodro, leaving at the same time as he did and together with the entire progressive part of the faculty of Moscow University, which had been crushed by Minister Kasso, became an assistant in physics at Shanyavsky University. At the same time he became the closest assistant of P. P. Lazarev, with whom he worked later in various institutes and laboratories until the end of his life. Thus, from 1912 to 1924 N. K. Shchodro was an assistant at the Department of Physics of the Moscow Higher Technical School. From 1916 to 1918 he was secretary and, together with Academician P. P. Lazarev, one of the organizers of the Physical Society of the Moscow Scientific Institute; from 1918 to 1923 he was head of the optical department of the physical laboratory of the Higher School of Military Camouflage. From 1920 to 1932 he worked at the Institute of Physics and Biophysics of the People’s Commissariat of Health, where from 1926 to 1932 he was deputy director.

To this period belong N. K. Shchodro’s investigations of photochemical reactions in dyes, closely connected with the work of P. P. Lazarev. On this subject N. K. published seven articles in the Proceedings of the Academy of Sciences (1919), in the Proceedings of the Physical Institute (1920), and in Journ. de Chim. Physique (1929). N. K.’s first works on this question were devoted to studying the change in the conductivity of a colored medium under illumination by light. For stained collodion films it was established that the increase in conductivity upon illumination is proportional to the amount of radiant energy absorbed by the film. Thus, the presence of ionization of the film, produced—

occurring as a result of the dissociation of phototropic dye molecules under the influence of light. In subsequent works on photochemical reactions in benzene solutions of dyes, N. K. discovered a very interesting fact, namely the presence of a negative temperature coefficient of the reaction for a number of dyes; the absence of a dark reaction in these processes was also shown.

Among N. K.’s photochemical studies is his later (1930–1931) unpublished work devoted to the study of the transition of \(SO_2\) into \(SO_3\) under the influence of ultraviolet rays. This work, assigned by order of the Chemistry Committee under the Council of People’s Commissars, is of great practical interest in connection with the problem of obtaining sulfuric acid from exhaust gases. In the course of the investigation, the wavelength in the ultraviolet region of the spectrum optimal for the reaction was established and the reaction yields were found. In carrying out his work on photochemistry, N. K. Shchodro designed a number of optical instruments of original construction: spectrographs, photometers, etc.

Next comes a series of N. K. Shchodro’s geophysical works, of which only two were published, namely: a study of the magnetic properties of ore from the Kursk magnetic anomaly (Journal of Applied Physics, 1926, and Gerlands Beiträge z. Geophysik, 1927), and a measurement of the dielectric constants of rocks (together with N. M. Maslov, Proceedings of the Academy of Sciences of the USSR, 1935). N. K. began studying the physical properties (magnetic, electrical) of rocks in connection with geophysical methods for prospecting mineral deposits during his work as head of the Magnetic Laboratory of the Commission for the Investigation of the Kursk Magnetic Anomaly (1920–1926), and later continued it at the Petroleum Geological Exploration Institute and the Trust of Geophysical Prospecting Methods (1932–1937).

In the first work N. K., with his usual thoroughness, developed two methods for measuring the magnetic properties of ore (magnetic iron ore with quartz): a magnetometric method using a tangent compass according to Helmholtz, and a ballistic method for fields up to 1,000 oersteds. The accuracy of the setups was very high. Hysteresis curves were also obtained for a number of ore samples, and the coefficients of magnetic permeability were found.

A continuation of these works is the study, carried out by N. K. Shchodro together with A. P. Ertel, of the magnetic properties of ores and rocks of medium magnetization in weak fields, of the order of the Earth’s magnetic field. The ballistic method for this purpose was further refined and improved. A considerable number of samples of various rocks were studied, namely: granite, granodiorite, diorite, diabase, and pegmatite.

To determine the dielectric constants of rocks, N. K. Shchodro, with the participation of N. M. Maslov, constructed a high-precision installation based on the beat method. Of the numerous measurements, only a few results were published for a series of marbles, shales, gypsum, labradorite, and granite; in this work the influence of moisture content on the dielectric constant of rocks was studied, which is of very substantial importance for electrical methods of prospecting mineral deposits.

Further, for the purposes of geophysical research, N. K. Shchodro built a number of seismographs of original construction for recording both horizontal and vertical seismic waves. The main part of these seismographs consists of a metal cylinder suspended eccentrically on a thread in a vertical or horizontal position. The seismographs are equipped with magnetic damping.

Being an experimental physicist, N. K. Shchodro was also keenly interested in problems of theoretical physics. Thus, in 1927 he published a work on the theory of capillary phenomena. While engaged in the experimental study of dielectric constants, N. K. Shchodro became interested in Debye’s theory and translated into Russian his monograph Polar Molecules. Among N. K. Shchodro’s other literary works one should also mention the book issued by ONTI in 1936 — N. Shchodro, G. Gaalyk

NIKOLAI KSAVERYEVICH SHCHODRO

and Hummel, Magnetic Methods of Applied Geophysics, which is a complete revision of the book by the German authors; the second part of the book, Terrestrial Magnetism, was written by N. K. Shchodro almost entirely anew.

In the last years of his life (from 1933), N. K. Shchodro worked as head of a department in the Laboratory of Biophysics of VIEM (from 1938—the Academy of Sciences of the USSR). N. K. Shchodro devoted this period to the study of the dielectric constants of electrolyte solutions, as well as colloids (biocolloids), at low and high frequency. In carrying out these studies, N. K. developed a number of methods for measuring the dielectric constants of solutions of both low and high conductivity; unfortunately, these works were never published. Among them the following should be noted: a method for measuring the dielectric constant based on the oscillations of a metallic ellipsoid of revolution (elongated and flattened) in an electric field; a method for determining the absolute value of the capacitance of small capacitors by direct alternating current; the theory of oscillations of an electric resonator containing, in addition to self-inductance, two capacitors connected in series, etc.

N. K. Shchodro was a great master of delicate physical experimentation and an extraordinarily ingenious designer. Despite these excellent qualities of a scientific experimenter, and despite the fact that N. K. always worked very hard, he published a comparatively small number of works. This is explained by the peculiarities of his character, in particular by his very great exactingness toward himself and toward his work.

N. K. Shchodro did not have a large number of students, but the scientific collaborators who worked with him in various laboratories very often turned to him for advice in carrying out their scientific work and always received from N. K. an exhaustive answer to the question posed and valuable advice that helped them overcome experimental difficulties encountered on the path of scientific research. All who worked together with N. K. Shchodro in the institutes and laboratories mentioned above knew him as a man of exceptional kindness, exceptionally considerate, responsive, and attentive to his comrades, to whom he was always ready to come to the aid in a difficult moment both in scientific work in the laboratory and in life.

M. P. Volarovich and B. V. Deryagin, Moscow

1. The materials for the preparation of this article were kindly provided to us by O. P. Shchodro, the widow of the late N. K. Shchodro. ↩