Читать книгу Geochemistry and the Biosphere - Vladimir I. Vernadsky - Страница 13
Оглавлениеthe history of geochemistry
1 geochemistry as a science of the twentieth century
We are living at a turning point in a remarkable era of human history. Events of extreme importance and profundity are taking place in the realm of human thought. Our fundamental views of “the Universe,” “Nature,” or “the Whole,” so much spoken about in the eighteenth and the first half of the nineteenth century, are changing before our eyes with incredible speed. Not only theories and scientific hypotheses, those ephemeral products of intellect, but also new exact empirical facts and generalizations of exclusive value make us rebuild and reconstruct the picture of nature that has remained untouched and almost unchanged by many generations of scientists and thinkers.
The new worldview, in fact the profound renewal of the centuries-old ideas about our surroundings and ourselves, captures us more and more every day. It inevitably penetrates into the domains of separate sciences, into the field of scientific work. These new views concern not only the inert matter that surrounds us, but they also embrace the phenomena of life; they change our notions in the fields of knowledge that we consider the closest to us and the most important. We can say that never in the history of human thought, have the idea and feeling of the whole, and of the causal interrelation of all observed phenomena, possessed such depth, sharpness and clarity as they have reached now in the twentieth century.
The study of the change that has taken place in these ideas and notions makes us think that we are still very far from the ultimate result, and that we have hardly begun to realize the route that the new scientific work has taken. This must be taken into account while evaluating the new concepts of atoms and chemical elements that penetrate our present-day science. They are taking shape in the unsteady, changing, and almost unfamiliar picture of the cosmos. Atoms and elements – the old intuitions of ancient thought – are constantly changing their image and taking new forms in these new and contradictory circumstances.
Each chemical element, we think, corresponds to a certain atom or atoms that are distinctly different in composition from other atoms corresponding to other chemical elements. The atom of the science of the twentieth century is not the atom of the ancient thinkers of Hellas and India, and neither is it the atom seen by the Moslem mystics of the Middle Ages and by the scientists of the last four centuries of our civilization. It is quite a new idea – a new notion. And although the historical roots of our present-day thoughts can be traced back to the atoms and elements of ancient science and philosophy, the changes undergone by them are so great that there is nothing left from the old concepts except the names.
Everything has changed crucially. Maybe it would have been more correct to give a new name to the “atom” of the twentieth century, because it could be done without doing any harm to the historical truth. Our atom does not in the least resemble the matter it forms. The laws of its existence are not similar to the laws of the matter formed by it. In matter, in its physical and chemical characteristics, we observe only general statistical manifestations of large conglomerates of atoms. These show, in a vague and complicated form, only an insignificant part of the characteristics of the atoms themselves, and of their inner structure.
A deep gap separates the scientific model of our surroundings and ourselves – according to the manifestations conditioned by our senses (the macroscopic view of the cosmos) – from the scientifically constructed cosmos where the atom reigns (the microscopic view of the cosmos). The principal physical notions, as well as the method of scientific thinking, suffer a crucial change in these manifestations. As soon as we make scientific advances into the world of the atom, our concept of physical causality sharply changes and deepens, while the century-old ideas about it are destroyed. [In addition to the micro and macro concepts of matter] a third aspect of the cosmos is taking shape at present thanks to the success of astronomical observation and research of the twentieth century: the world of space-time scientifically embraced by large numbers, that – like the atom world – cannot be measured by our senses.
These three concepts about the world, about the reality covered by science, are not coordinated. Everything is in a state of creative motion, both scientifically and philosophically. The atom and its corresponding chemical element are present in all three forms of the worldview. It seems very probable that with attempts at further generalization, great significance will be gained through the trend of scientific synthesis that was put forward in the middle of the eighteenth century by the great Serbo-Croatian thinker, Ruggiero Boscovich (1711–1787), and that is drawing more and more attention at present.
An atom is not a formless and structureless “center of forces,” but a regular conglomerate that according to Boscovich is comprised of matter and universe.1 The history of this trend of thought, which seems to outline and anticipate the way of future scientific thought, has not yet been written. Another great natural scientist, Boscovich’s contemporary, James Hutton (1726–1797), approached the same world view independently and laid the foundations for contemporary geology.
An integrated scientific worldview does not yet exist, but the countless new facts unveiling the structure of nature in all its aspects make our thought go deeper and deeper into the realm of atoms, and still further, to the minute entities of which the atoms consist; the real units of time and space. These facts have led to the creation of new scientific disciplines that differ from the former ones, which studied matter – the conglomerate of countless atoms – from a statistical standpoint.
In the twentieth century we are witnessing the flowering of this new kind of science of individual atoms in the form of atomic physics, radiology, radiochemistry, and most recently geochemistry – a small part of astrophysics. Geochemistry deals with the scientific study of chemical elements, i.e., the atoms of the Earth’s crust and the whole planet. It studies their history, their distribution and motion in space and time, and their ‘genetic’ correlations on our planet. It is distinctly different from mineralogy, which studies in the same time and space of Earth’s history only the history of atomic compounds, molecules, and crystals. In this strictly limited terrestrial planetary field, geochemistry discovers phenomena and laws whose existence we could only anticipate in the boundless fields of celestial space.
It is obvious to us now that the chemical elements are not distributed chaotically in conglomerates of matter in spaces such as nebulae, stars, planets, atomic clouds, and cosmic debris. Their distribution depends on the structure of their atoms. The atomic geometry of space and time, expressed by the history and distribution of atoms throughout the whole length and duration of the cosmos, exists in large and small forms, in the structure of both a cosmic nebula and a minute organism.2 The same laws regulate great celestial bodies and planetary systems, as well as the smallest molecules and maybe even the more restricted areas of the separate atoms.
More than two and a half centuries ago, the Dutchman, Christiaan Huygens3 (1629–1695) – one of the greatest scientists – discovered the inevitable identity of matter and the forces of the Universe, and the manifestations of life throughout its entirety. The identity of matter and forces was based on the gravity laws of his contemporary, I. Newton. It embraced also the Cartesian philosophy that reigned supreme in physicists’ minds and hindered the understanding of Newton’s scientific discoveries and generalizations of 1676 up until 1730–1740. In the seventeenth century, the notion of the unity of, speaking in modern terms, matter and energy throughout the entire cosmos, the whole of space and time, that had sometimes sprung up in the course of centuries, became part of the scientific understanding of the Universe. But Huygens was one of the few scientists who had clearly expressed the inevitable consequence of this notion: the cosmic unity of life we study in the biosphere.
One hundred fifty years after Huygens, the Englishman W. Hyggins, through scientific experiment and observation by spectrum analysis, proved the identity of chemical elements (atoms) of the stellar worlds based on terrestrial manifestations. The present-day creative explosion of ideas has not shattered this essential principle. He expressed it in the new concept of the identity of the basic elements (electrons, neutrons, protons, and the newly discovered positive electrons, or ‘positrons’), which make up atoms or chemical elements, and also in that of the genetic, though complicated connection existing between the atoms of different structures. Studying the laws and regularities of the history of elements of our planet, and studying the structure of the Earth’s atoms, we study at the same time the regularities of the smallest spaces and smallest moments that are indivisibly connected with the great whole of the cosmos. There are deep analogies between them and even more than just analogies.
Protons, electrons, positrons, photons, and quanta embrace the whole of time and space – all three aspects of the cosmos. They also constitute and embrace atoms. But chemical manifestations of atoms studied in geochemistry are only a small part of the phenomena connected with these main elements of the cosmos. The chemistry of the cosmos and geochemistry, or the atomic chemistry of the planet in space and time, is a small though important part of the reality studied by science. But we must remember and mention at once that the material substratum of space and time is not determined by chemical phenomena and the chemical characteristics of atoms.
2 forms of existence of chemical elements
Geochemistry, or the history of the chemical elements of our planet, could appear only after the new notions about the atomic and chemical elements had come into being. It could appear only recently, but it is rooted deeply in the history of science. Now we can see how the separate studies of different scientists of the past, which were not quite clear to their contemporaries, appear in a new form under the influence of the great scientific generalizations of the present – how they are receiving a new meaning and prove to be interconnected. Unfortunately, I cannot dwell upon the history of these ideas and upon the rise of geochemistry in detail. The preliminary work has not been done yet, and no full and coherent account can be given here of the way human thought has developed in this field.
No doubt, in the seventeenth century and earlier, systematic studies of geochemical problems were undertaken. A future historian of science will discover a fruitful scientific trend, list the names, trace a series of discoveries, observations and facts that are getting more and more precise, and find the roots of the most significant contemporary empirical generalizations and scientific ideas. This trend had become especially powerful and important by the end of the seventeenth century. Here I shall mention the name of the man who probably realized more of the scope and the importance of the phenomena encompassed by modern geochemistry than anybody else. This was Robert Boyle (1627–1691), a founder of the theory of chemical elements and a creator of modern chemistry.
The history of natural waters and of the world’s ocean in particular, the atmosphere as a weighty gaseous medium, the solution of gases in water, the first exact delineation of chemical elements in terrestrial bodies, and the beginning of precise chemical analysis of terrestrial products have all originated from Boyle’s works. I cannot, however, dwell upon these and other forgotten scientific studies, which have not actually passed unnoticed, and which have had a certain influence on the contemporary scientific mind. They lasted for almost two centuries. As early as in the second half of the eighteenth century, geochemical problems began to arouse scientific interest, although the idea of a chemical element was vague and far from the notions of the nineteenth and twentieth centuries.
G. F. Rouelle senior (1703–1770), and his even greater junior contemporary, L. Lavoisier (1743–1794), whose creative work was stopped while fully blossoming, had already posed these problems clearly enough. We cannot imagine the heights Lavoisier4 could have reached. Before his death he began to approach the deepest geochemical problems in his works concerning water and the physiology of breath [respiration]. Rouelle – the senior – published very little, but he influenced his contemporaries greatly by his public experimental lectures on chemistry that he delivered in Paris at the Royal Botanical Garden. All the intellectuals of Paris, or even of Europe, gathered for these lectures, and numerous foreigners who were in Paris – often great minds – attended these lectures. Nowadays it is very difficult to realize Rouelle’s influence; nobody has even tried to do it. But it is indubitably enormous, as it spread from Paris throughout Europe and survived his death. In the works of Lavoisier on the history of elementary gases and on the history of water, there are shining examples of geochemical generalizations expressed in the scientific language we are used to. Due to the great influence of Lavoisier’s ideas on the whole of modern chemistry, geochemical problems were introduced as well. Since then, some of these problems have begun to be included in chemistry courses.
His elder contemporary, Leclerc de Buffon (1707–1788), who was still very far from our present-day notion of chemical elements, presented in his history of minerals a series of brilliant and interesting generalizations and posed a series of significant geochemical problems. He was able to do this not only because he was a profound observer of nature who covered all the scientific knowledge of his time, but also because he lived in the midst of social activities and was an agronomist and a technologist. We find geochemical problems in his chapters on the history of native elements, and on that of metals in particular. But we find them also in other parts of his Les Epoques de la Nature (1780) and Histoire Naturelle, Générale et Particulière (1749 and following years). Not only was Buffon a great writer, he was also one of the greatest and most profound naturalists, one of the few people who had indeed observed the Universe as a whole. In these “Essays” we shall come across his ideas and their consequences more than once.
We cannot but mention also M. V. Lomonosov (1711–1765), another contemporary of Rouelle and Buffon. Only nowadays have we fully appreciated Lomonosov’s scientific thought, which foresaw the future ways of science. In his forgotten works, which have been published badly and incompletely, his understanding of geochemical problems can be seen clearly and distinctly. In the Petersburg Academy of Sciences he had followed his own path, onto which scientific thought arrived only in the twentieth century. Incessantly he went deeply into the chemistry of natural bodies in general and in connection with Earth’s history. By the beginning of the twentieth century, the new chemistry had been integrated into scientific thought: the chemical element had received a new understanding, far from that attached to it by Lavoisier. Geochemistry had seemed to be on the verge of appearing, but it was created much later. Apparently, the empirical material had not yet been sufficient and understanding of the chemical element itself was not clear enough.
It was the time of the creation of present-day chemistry and geology, and their synthesis gave birth to geochemistry. At the same time, applied scientific disciplines were being created on the basis of the new scientific ideas of matter and our planet – they were understood as technology then. This is extremely important too, because both in ‘technology’ in the broader sense and in pure knowledge we come across thoughts about geochemical problems – the deepening of these problems. The history of chemical elements in the Earth’s crust, their role in different chemical processes, and particularly in the phenomena of life – both in living nature and in daily human life – has permeated scientific thought since the end of the eighteenth, and beginning of the nineteenth century; it has had various manifestations occurring everywhere.
I shall mention three of the most outstanding predecessors of modern geochemistry of the last century. These are the Englishman Humphrey Davy (1778–1829), the Prussian German J. C. Reil (1759–1813), and A. von Humboldt (1769–1859). The brilliant key work of A. von Humboldt, a Prussian by origin, was published outside Prussia. As for himself, in the first decade of the nineteenth century he was completely under the influence of the intellectual atmosphere of Paris.
Humphrey Davy was a brilliant experimenter, physicist, and chemist who covered all the science of his time; he was a thinker possessing a deep poetic understanding of nature. He always connected science with life and was one of the most brilliant figures of the first half of the nineteenth century, which was so rich in talented people. Davy made a tremendous impact upon the science of his time by his lectures, numerous articles and books, and by brilliant experiments. In his works we find a lot of data about the history of chemical elements in the Earth’s crust. In this field he developed the ways discovered by Rouelle and Lomonosov on a new scale. His works were a prototype of all the later treatises of chemistry in which the account of the properties of chemical elements is always connected with their geochemistry. In the later works of Dumas, Bercelius, Liebig, Mendeleyev, and other, no less talented scientists, we always find speculations or brilliant generalizations concerning geochemical problems. After Davy, during the entire nineteenth century, geochemical problems were included into inorganic chemistry courses; they were studied while discussing particular chemical elements.
The fate of Reil was quite different. One of the most outstanding doctors of his day, absolutely committed to helping the suffering, he did not spare himself and died on duty. Reil died in the very midst of his scientific searches. Being a doctor, an anatomist, a psychiatrist, and a physiologist, he was not interested in geochemical problems directly. But he was a man of broad philosophical thinking, a naturalist, like all the genuine doctors of his day. As a philosopher he shared the trends of natural philosophy, and apparently he was close to Schelling, but his thought was independent. His contribution to the history of geochemistry is connected with the study of the chemistry of organisms. He was the first in the era of the new chemistry to suggest the importance of the chemistry of organisms, and in this respect he was far ahead of his time.
The roots of Reil’s aspirations and ideas go far back into the medical tradition. Beginning with the petrochemists of the seventeenth and eighteenth centuries, maybe even with Paracelsus (Bombast von Hohenheim, 1493–1541), the importance of chemistry in medical systems and in the understanding of healing the sick had never left the intellectual horizon of doctors. Generations of doctor-chemists follow one another incessantly for centuries. Reil considered the thorough, quantitative chemical study of organisms necessary, and he searched there for the answer to the manifestations of life. He was an innovator whose work was stopped by death at the very beginning. It is difficult to say what Reil’s contribution could have been, had his life been longer.
This was also the way of thinking of one of the most striking people of the first half of the nineteenth century: Alexander von Humboldt. In his early works, especially in “Flora Fribergensis Specimen” (1793), written before he plunged into South American nature, A. von Humboldt had come very close to many of the present-day problems of geochemistry. These studies of the young Humboldt were interrupted by his long journey, the processing of its results and the creation of the striking synthesis presented in his Cosmos. As an old man, in the fifth volume of Cosmos, he returned to one of the geochemical problems: the influence of life on its surroundings. But death stopped this work in the middle of a word.
In the paper of 1793 mentioned above, there was a brilliant effort to describe living organisms from the point of view of their chemical elements; being a mineralogist and a geologist, Humboldt never ceased seeking for their origins in the inert matter surrounding the plants. Decades passed until the problem was posed again as clearly as it had been by Humboldt. His way of putting forward the problem of the geographical spreading of organisms goes far beyond the limits of the studies of his followers; and deeper than the new branches of geography that appeared under its influence; it approaches the geochemical concepts of our days. He considered living matter to be an unbreakable and regular part of the planet’s surface, inseparable from its chemical environment.
During the entire nineteenth century, the field of contemporary geochemistry was being prepared. Step by step, the picture of the unity of the chemical composition of the Universe was becoming clear. This unity was first put on an experimental basis after the idea of the cosmic origin of meteorites penetrated the scientific mind. That idea was born in the first quarter of the nineteenth century, thanks largely to the continuous (1794–1826) scientific work of E. F. Chladni (1756–1827), an original scientist who, like Humboldt, stood apart from German university science. Chladni, who was not a chemist, followed his own path in life and was an innovator in science. The chemical composition of meteorites being identical to that of terrestrial bodies was first stated by E. C. Howard (1802), and at the same time J. L. de Bournon found out how they differ mineralogically. Both statements soon entered the scientific mind, but conclusions were drawn much later.
The notion that the chemical elements of living organisms were identical to those of inert matter was slowly acknowledged by science. Until the 1740s, it was not considered scientifically proven and was checked by special experiments. By the middle of the nineteenth century, following the methods brilliantly worked out by H. Davy, scientists had discovered the principal features of plant nutrition, which were then immediately taken up on a planetary scale (i.e., studied not only in their biological, but also in their geochemical aspects). This tradition has continued since the time of Lavoisier.
J. B. Dumas (1800–1884), J. Boussingault (1802–1887), K. Sprengel (1787–1859), J. von Liebig (1803–1873) and many researchers who followed them, or their contemporaries whose work was partly independent, stated the geochemical significance of green life. As we shall see, this life refers to the main part of the living matter of the biosphere. Dumas, Boussingault, and Liebig discovered the importance of green life in the gas exchange of the planet, and apparently it was Boussingault who had the deepest understanding of it, for he understood the geochemical aspect of the phenomenon best of all. He came across it outside the laboratories – in nature – during his long stay in the tropics and his studies of volcanic phenomena and minerals. In this field he was one of the shrewdest thinkers of the nineteenth century, and up till now we find in his works new material that has not been covered by scientific thought yet. Sprengel and Liebig furthermore discovered the real significance of the ashy elements. The theoretical constructions of Liebig influenced our understanding of these phenomena and completely reversed the explanation of the century-long characteristic of human culture – the importance of fertilizers for the productivity of soils. They also showed the geochemical role of green plants by using the compounds of phosphorus (this was clear to Boussingault too), potassium, and other elements needed by the plant.5
At the same time chemists did other studies on the minerals, waters, gases, and rocks surrounding us. Many scientists, especially chemists, considered mineralogy to be “the chemistry of the Earth’s crust,” as I. J. Bercelius called it. Gradually, precise research on the nature of minerals amassed an enormous amount of material. At the same time, by the end of the nineteenth century, the chemical analysis of rock formations, the research on waters, and the chemical study of fossil minerals gave a solid basis for empirical generalizations, for the creation of biochemistry.
Now we can see (it was remembered in 1931–1932) that different people understood the process being in progress quite clearly, and that the notion and the word “geochemistry” had already been created by that time. It was done in the 1830s and early 1840s by an original scientist from Basel – C. F. Schoenbein (1799–1868). His ideas were forgotten, but a historian of thought cannot forget the real influence of such an outstanding and brilliant personality as Schoenbein, who discovered ozone and worked in his own peculiar way. Schoenbein was not alone; he exerted a great influence on his surroundings. His articles and, as we can see now, his letters, are full of ideas and research that went beyond the limits of the science of his day; these were partly echoes of the past and partly anticipations of the future. Apparently, a friend of Schoenbein’s, M. Faraday (1771–1867), was not indifferent to his geochemical interests; his life was closely connected with that of Humphrey Davy whose significance for geochemistry I have already mentioned.
In 1842 Schoenbein wrote: “A few years ago I had already put forward the idea that we must have geochemistry before speaking about a real geological science that pays at least as much attention to the chemical nature of the matter comprising the Earth, and to their origin, as to the relative antiquity of these formations and the fossils of antediluvian plants and animals buried there. Of course, we can be sure that the geologists will at last cease to follow the trend they are supporting now. In order to broaden the limits of their science, they will have to look for new auxiliary means as soon as fossils fail to satisfy them. They will undoubtedly introduce mineralogy and chemistry into geology then. The time for this to happen does not seem to me very far from now….”6 Now these words seem prophetic to us. Schoenbein was mistaken regarding one point though: the time for his ideas came only in the twentieth century, decades after his death; then the word he had created was reborn and embodied by a new geological science.
By 1850, namely during the period of 1847–1849, brilliant and outstanding geochemical generalizations were published in scientific works that had collected an enormous amount of exact facts, which thereby entered general scientific thought and influenced it. This was done by three prominent naturalists who worked independently from each other, and whose works complement one another. None of them could cover the whole field of geochemistry by one synthesis but, as we see now, the results of their extended works which appeared almost simultaneously, presented a general outline for our new science. Nevertheless, their contemporaries did not see it – they noticed only contradictions and could not perceive them as part of one and the same whole.
These three naturalists were: Prof. K. Bischof (Bonn), who published in 1847 the first volume of his Lehrbuch der Chemischen und Physikalischen Geologie;7 Prof. Elie de Beaumont (Paris) who published in Bulletin de le Societe Geologique de Paris a brilliant memoir about volcanic phenomena,8 which was not understood by his contemporaries; and Prof. J. Breithaupt (Freiberg), who synthesized in 1849 the century-long work of the Freiberg mineralogy school in his book Paragenesis der Mineralen.9 In these works we already have clear and solid roots for the main data of geochemistry. If somebody at that time, for instance in 1850, could have embraced all that material at once, we would have had geochemistry in the nineteenth century. Nevertheless, it was formed only in the twentieth century.
No one was able to embrace all this material due to the peculiar atmosphere of geological work at that time. It was the time of the argument between neptunists and plutonists, which was dying away but had not been finished yet, and which had involved three generations of scientists in the eighteenth and nineteenth centuries. One party, the neptunists, considered surrounding terrestrial nature to have been created by the forces of water and formed at normal temperature and pressure. Life, which was closely connected to water, occupied its honorable place in the creation of nature. According to the neptunists, life was a great force, not an accidental phenomenon in the history of the planet. The other party – the plutonists – paid no special attention to the forces and phenomena of the Earth’s surface. They believed that the great forces inside the planet, which they thought to be still in a state of incandescent magma, were creating the nature of the Earth. Life, in all its variety and apparent importance, was just an insignificant peculiarity that did not reflect the main phenomena of the planet. The forces, whose activity manifested themselves in volcanoes, geysers, earthquakes, and thermal springs, formed all the principal features of the Earth’s surface and influenced the formation of mountains, rocks, and conglomerations of water and gases.
These two opposite concepts of our planet really concerned the main features of a worldview. The choice between them, once taken, led to opposite conclusions, which had great vital significance for the importance of life in the structure of the cosmos. The meaning of these old arguments, in the mental life of that time, can be understood from the creative work of the great naturalist and poet – a brilliant and passionate neptunist – J. W. Goethe. The second volume of his “Faust,” which embodied his lifelong efforts to express his concepts of the future and the tasks of human life, is permeated by reflections and echoes of this argument.
K. G. H. Bischof (1792–1870) became a neptunist having realized the significance of the Earth’s surface for the history of the planet through long speculation and experimentation; in the early years of his scientific life he had been a plutonist. This revolution in his views affected his whole work. He proved the importance of water, collected an enormous quantity of facts, gave clear pictures of the history of many chemical elements, and eventually showed that in the phenomena of inert matter, their history could be reduced to cyclical processes that, in the first part of his paper, he considered a typical feature of organogenic elements. For organogenic elements this picture had already been given by Dumas, Boussingault, and Liebig. In this connection, the phenomena of life in the chemical processes of the Earth were put at the forefront in his paper. The influence of his work was immense not only on the continent, but also in English-speaking countries; Bischof himself was connected with English scientific circles.
Unlike Bischof, Elie de Beaumont (1798–1874) was a plutonist, who put forward that the connections between chemical elements and the regulations of their locations are consequences of magmatic and volcanic processes. For a long time, the brilliant work of Elie de Beaumont attracted little attention outside France, partly because of the domination of neptunic ideas and partly due to his unsuccessful hypotheses about the formation of mountain chains. But long after his death the truth of his generalizations was confirmed by exact observation, and became an indispensable part of geochemical work.
The exact empiricist, J. Breithaupt (1791–1873), also followed an independent route. Using the experience of mining, he put forward correlations between elements that are situated together – and which went beyond the schemes of pure neptunists and plutonists. The processes studied by Breithaupt did not fit into their simple schemes, and he discovered new phenomena of our planet that had been one-sidedly described both by Elie de Beaumont and by Bischof. Breithaupt was not alone; exact empiricists, observers of ore deposits amongst whom were both neptunists and plutonists, were following the same route at that time. The most outstanding investigations were those of J. Durocher (1817–1860), J. Fournet (1801–1870) and W. Hennwood. New properties of water were found, and the influence of the high temperature of lower geospheres became clear. The investigation of these processes from the standpoint of ore deposits – mainly metals – inevitably made the scientists study the history of chemical elements in the Earth’s crust.
As both plutonic and neptunic schemes were disappearing, the scientific work of the second half of the nineteenth century continued in all these directions. Geology soon left the old schemes and covered the complexity of nature with more diverse theories. At the same time, the chemical mind was distracted from geochemical problems; in the history of chemical elements much attention was being paid to properties 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 first edition was published in 1908. This book exerted a great influence on scientific thought and was published in five editions (the last one in 1924).13
A huge amount of factual data is collected in this book. Clarke tries to give the exact numerical data concerning the history of the main chemical elements. Although in his youth (1872) he had been one of the first scientists who had dared to scientifically tackle the issue of the possibility of turning one chemical element into another in connection with their history in the cosmos, and although fifty-three years later he returned to these cosmogonic generalizations, in his Data of Geochemistry, he pursued not hypotheses and wide generalizations, but comparison and criticism of exact numerical data on the history of chemical elements in the Earth’s crust and in its processes. He was interested in the study of the composition of the sea, the average composition of rivers, and the study of the Earth’s crust; everywhere he introduced new numbers and critically revised the old ones.
Clarke’s book has in fact become the foundation for further generalizations and further geochemical work.14 It summed up and covered a tremendous amount of material connected with the numerically exact chemical, geological, and mining research on the American continent. At the same time, an American who had worked in Canada, his elder contemporary T. Sterry Hunt (1825–1892), was also attempting “the synthesis of the Earth,” as he put it. Sterry Hunt’s influence was great, but he left a lot of room for theoretical speculations which were not always successful. Clarke’s synthesis, which was being built at the same time and on a firm empirical basis, proved to be more solid.
Having collected the facts and having empirically generalized them into the new science of geochemistry, Clarke finished Bischof’s work in the twentieth century. His book gave a summary of the tremendous work of thousands of people over a long period of time. As early as 1882, his first calculations of the gross chemical composition of the Earth’s crust had appeared. After that, Clarke incessantly altered and improved them (for the last time in 1924, together with H. Washington). These data – Clarke’s numbers – did not influence the scientific mind for many years but were objected to, and were appreciated for their great significance only in the last decade. This significance may turn out to be even greater than Clarke thought if the resemblance of the outer envelope of our planet to the outer envelopes of other planets can be proven.
As we shall see below, Clarke followed the routes outlined by W. Phillips as early as in the beginning of the nineteenth century, and he was the first to seek not an approximate numerical estimation of the phenomena, but a concrete exact number. Clarke did not formulate the task of geochemistry distinctly and categorically as being the study of the history of the planet’s atoms, this trend in geochemistry appeared later and aside from his direction of thought. But thanks to the real significance of Clarke’s numbers in the new theories of atoms, to their influence on the physical and chemical thought of the twentieth century, his work has completely entered notions that were forming outside the realm of his thought. His geochemistry corresponded to the chemical and physical geology of Bischof but it met a different scientific environment.
The notion of geochemistry as a science about the history of terrestrial atoms appeared as a background to the new atomistics, chemistry and physics, in close connection with the idea of mineralogy typical of the Moscow University in 1890–1911. Both in teaching and in scientific mineralogical work there, most attention was paid to the history of minerals – their genesis and their change – which usually occupied a second rank in the mineralogy of schools of higher education at that time. With such a presentation of mineralogy, geochemical problems were presented on a larger scale, and were considered more important15 than in the common university courses of inorganic chemistry. Gradually, the work of the Mineralogy Chair of the Moscow University, and later the work related to it at the Mineralogy Museum of the Academy of Sciences, was more and more directed toward geochemistry. The name given by Clarke immediately found content here (although different from his own) and fruitful ground. The phenomena of life, and the mineralogy of sedimentary rocks in connection with radioactivity and general issues concerning the properties and character of atoms, occupied a considerable place. In 1912 in Moscow, in the university named after Shaniavsky, A. E. Fersman delivered the first university course of this new science. Furthermore, a series of A. E. Fersman’s and Ya. V. Samoylov’s works (1870–1925) have firmly established the traditions of geochemical work in our country.
By the twentieth century, the study of ore deposits, which had made great progress by that time, contributed greatly to the creation of geochemistry. The close connection between geochemical problems and insights about ores, which had led to the generalizations of Bischof, Breithaupt, and Elie de Beaumont in the previous century, has never been interrupted. But in the new century it acquired quite a different appearance due to the progress of chemistry, the unusual deepening of technology, and the great scope of extracting old metals and introducing new metals into the structure of human economy and life. In our century this phenomenon has acquired an extraordinary form: that of the global economy.
The works of the Frenchman, L. de Launay, and the German, A. Stelzener (1840–1895), were of great influence and posed geochemical problems. But considering the problems of the theory of ore deposits or applied mineralogy, most significant in the creation of the field of geochemistry are the works of the Norwegian, I. Focht (1858–1932), which are closely connected with the century-long mineralogical research based on the nature of Fennoscandia, and the works of North American mining engineers such as C. Van Hise and W. Lindgren. They connected the problems of geochemistry to that of ores, and in this way gave it a great practical value. This applied significance of geochemistry is growing rapidly during recent years. It manifests itself in our country as well, but we have to say that the conditions for its correct development are not favorable here.
Modern geochemistry is closely connected with the work and thought of another scientist – Prof. V. M. Goldschmidt – who in 1930 created the most powerful scientific center of geochemical work in Göttingen, Germany, although he himself was a product of the century-long scientific traditions of the Norwegian school of mineralogy. From 1914 to 1930, V. M. Goldschmidt, disciple of the outstanding mineralogist V. Brögger, was a professor in Christiania (now Oslo), where he created a mineralogical and geochemical institute with a high level of scientific thought. The Institute of Göttingen made further progress. The nature of Fennoscandia gave the mineralogical work in that country quite a unique flavor; it is an area of ancient crystalline rocks, and radioactive minerals are also present.
Often they are quite unusual in beauty and manifestation, distinctly different from all others in their outer form, unique in color, shine, and chemical composition, and also in such physical properties as metamic structures, compounds of uranium and thorium, rare earths, titanium, niobium, tantalum, zirconium, and hafnium. The school of chemists and mineralogists, which was here for centuries, covered this most difficult group of terrestrial bodies and discovered in the native material a quantity of new minerals and new elements. Bercelius, proceeding from this native material, applied his thought and exact methods to the whole area of inorganic chemistry of the twentieth century.
At the end of the century, Brögger synthesized the mineralogical work of the Fennoscandian and German scientists with reference to the same natural bodies. W. C. Brögger (born in 1851), a man of rare knowledge and exactitude of work, is equally prominent in geology, paleontology, and crystallography. He is a first-class researcher both in the field and in the laboratory; he connected the chemical study of minerals with their crystalline structure, developing in this field the ideas of another Norwegian scientist, the chemist and mineralogist T. Hjortdal (1839–1925).
Brögger’s disciple, V. M. Goldschmidt, therefore approached geochemical problems in surroundings full of traditions. The deeper geospheres of the Earth’s crust that are located beyond the stratisphere and the biosphere drew his attention; they constitute the largest part of the substance of our planet open to research. Solid matter acquired a special significance, and due to a new specification of roentgenometric methods, led to creation of crystal chemistry, in which Goldschmidt played an important role. Working in this direction, and taking into consideration the processes of elements’ migrations in the vectorial solid medium, Goldschmidt introduced into geochemistry a notion fraught with many consequences: the notion of the chemical elements’ behavior, as conditioned by their structure. He pointed out the regularities of their manifestation in the solid medium forming the Earth’s crust. Goldschmidt’s Institute in Göttingen is at present the largest center for this kind of scientific work.
Geochemistry is developing rapidly now; its influence and significance in purely scientific issues is constantly growing and increasing. The preparatory period is over. Separate branches are beginning to spring up thanks to the close connection of the large complex of its problems with fields that are in fact separated from geological disciplines, one of which is geochemistry. In this way, biogeochemistry has begun to separate. In 1927, the center for research in this field was established in Russia at the Academy of Sciences: its Biogeochemical Laboratory, which is not very powerful as yet.16
table 1
Table I Periodic Table of the Elements. [This is a modern version, included for reference. It is a far cry from the original version by Mendeleyev, Vernadsky’s professor. Elements in italics have been created in laboratories of nuclear physics; all are highly radioactive. The names of these are interesting: After honoring Greek gods, places, and scientists, the namers apparently gave up with #104 and used a numbering system. Ed.]
