Geochemistry and the Biosphere. Vladimir I. Vernadsky

that did not seem to manifest themselves in the processes of our planet. The idea of a chemical element became more abstract, it seemed that there was an insurmountable barrier between chemical and geological sciences. This was clearly shown in the different classifications of sciences that were so numerous at that time. The state of mind of researchers was unfavorable for creating geochemistry.

      The generalizing and deep view of chemistry that brilliantly combined the traditions of Rouelle, Lavoisier, Davy, and Bercelius, and that was interpreted by such an original and powerful mind as D. I. Mendeleyev in his Foundations of Chemistry, stood absolutely alone. In Foundations of Chemistry, the problems of geochemistry and space chemistry were not only fully described, but were also often dominant. As always with D. I. Mendeleyev, it was not a repetition of someone else’s materials, but it contained something new, something found by his brilliant personality, grasped by his shrewd mind.

      In general, neither in geochemistry nor in chemistry did a favorable environment exist for the development of geochemical problems into an integral, separate, and scientifically based new discipline. The soil had not been ready, and it was slowly being prepared for decades, beginning in the second half of the nineteenth century. There were three changes in the ideas about the environment that provided a solid basis for this new science in the twentieth century.

      In the second half of the nineteenth century our notions about the chemistry of the cosmos began to change. The unity of its chemical composition, which – as we could see – had been clear to Huygens in the seventeenth century and had been confirmed by the analysis of meteorites, received a new and solid affirmation in 1859 with the discovery of spectral analysis by G. R. Kirchhoff (1824–1887) and R. Bunsen (1811–1899).¹⁰ This discovery expanded the human horizon enormously. In fact, it was one of the deepest insights into the structure of matter; spectral analysis proved the chemical unity of the universe. But at the same time, thanks mainly to spectral analysis and to the development of our notions about the complicated unity of matter expressed in its atomic aspect, which led to a deeper theoretical understanding of the great scientific generalization of the Periodic System of elements, thanks to all this, the very notion of the chemical unity of the world became enormously deeper and wider.

      On the one hand it became clear that the atoms of our planet were present in different states. It was also necessary to admit the existence of certain states of atoms (i.e., chemical elements of the universe) that cannot exist on planets including the Earth.¹¹ On the other hand a question arose whether the atomic manifestation of matter – its chemical composition – corresponds to the dominating mass of matter dispersed throughout the time and space of reality. The spectral analysis in the works of Kirchhoff and Bunsen clearly and definitely confirmed the existence of chemical elements in dispersion – all matter of the Earth being permeated by them. For some elements such as sodium this was already understood by H. Davy and then by others, but this notion entered the general scientific mind only after the works of Kirchhoff and Bunsen. Nevertheless, the idea of its importance for geochemical problems was put forward only in the twentieth century (1910). Up until now the phenomenon has not been completely covered by scientific thought and even less by experiment.¹²

      Apparently there is not only one form of planetary atoms in a specific state. It is clear that for some chemical elements, for instance lead, isotopic mixtures can differ. This is caused by radioactive dissociation and specific conditions of the atoms’ migration. It is possible that there is another phenomenon related to it such as the influence of life – the change of isotopic mixtures in the biosphere – but this issue is not quite clear yet. Eventually it was understood that geochemical problems made up an inseparable part of the problems of cosmic chemistry, that the chemistry of Earth was one of the manifestations of planetary chemistry, and that the theory of the geochemical character of chemical elements, i.e., geochemistry, was distinctly different from mineralogy, the study of molecules and crystals formed by atoms.

      Our idea of the unity of the chemical composition of the universe undergoes still deeper changes under the influence of the growing understanding of the fact that the atom is not the dominant form of manifestation of matter in the universe. Studying atoms gives no definite idea about the matter of the cosmos. Beyond atoms we can observe the realm of electrons, positrons, neutrons, free protons, and a series of unknown material particles dominating in mass. To a lesser degree these phenomena also cover the matter of the Earth, for instance the electrons of the ionosphere’s electric field. The electronic chemistry of general chemical physics must occupy the dominant place in cosmic chemistry and must take its place in the chemistry of our planet together with geochemistry and mineralogy.

      Since the last century, considerable changes have taken place in our scientific notions about the research area of geochemistry and mineralogy – the geological substratum of the planet. In the first half of the nineteenth century. it was considered indubitable that geological phenomena could serve as the basis for conclusions concerning the whole Earth. The dispute between plutonists and neptunists was based entirely on this assumption. The thin surface film, our biosphere filled with life, seemed to get lost and forgotten in the mass of the planet. Slowly but steadily, from generation to generation, these notions disappeared, because it was gradually discovered that all the geologically studied processes relate only to the outer part of the planet, the Earth’s crust. Processes that had formerly been related to the inside of the Earth proved to be external.

      Gradually the boundaries of the Earth’s crust were determined; they did not exceed the upper 100 kilometers. Geodesists were the first to take up this viewpoint, and as early as 1851 the English priest J. G. Pratt provided the foundations of the theory of isostasy; that is, the non-homogeneous structure of the outer part of the planet, the Earth’s crust, as opposed to the homogeneous structure of the deep layers of the planet. He pointed out that it was not the depth of the Earth but the Earth’s crust that was involved with the greatest phenomena we know on the surface of the Earth: the formation of mountain chains. Immediately, the English astronomer G. B. Airy (1855) expressed Pratt’s ideas more correctly, and explained them by the hydrostatic equilibrium of different heterogeneous parts of the Earth’s crust. Pratt’s ideas, formulated in a general form by the American geologist C. E. Detton thirty years later, gained scientific acknowledgment only in the twentieth century. Geologists, however, came to the same conclusions earlier and in a different way. Thanks to that insight, all views on geochemical problems changed clearly. The volcanic products, the products of life, and the sediments of the sea proved to be bodies of one and the same planetary field that, as well as the phenomena of life, is different from the large mass of the Earth. As a general geochemical understanding, the significance of life increased and changed essentially.

      In that period of time, another revolution in our general worldview was taking place. The old idea of J. Dalton and W. Wollaston, its logical consequences which were perhaps not quite clear to themselves, became reality; the atom and the chemical element proved to be identical. In order to understand the atom, one had to study the chemical element. The atom became as real to us as the chemical element; it acquired flesh and blood and became a real body. This achievement of science took place in the twentieth century, but the late decades of the previous century, in spite of what contemporaries thought, were already leading the scientific mind toward this generalization. It is well known that by the end of the nineteenth century, the atomistic view of Earth’s environment seemed to be losing ground and was being replaced by dynamic ideas about the world. In reality it was a mirage; in reality the atomistic view has never been as influential in the scientific worldview as today. True, the atom in the new worldview has little to do with the atom of philosophers and even of physicists; it is the chemical element of chemists in the form of an atom.

      All these changes had for the first time made it possible to embrace geochemical problems as a whole, as a special scientific discipline, and to separate geochemistry out as a science that studies the history of atoms (understood as the chemical elements on our planet). Actually, we are studying only its external envelope, the Earth’s crust. In particular, this separation of the new science was taking place more or less independently in different parts of the civilized world. In Washington, F. Clarke – a chemist from the American Geological Committee who had studied geological problems all his life – collected and arranged an enormous amount of material in his book, Data of Geochemistry, of which the