With the establishment of the knowledge of a state of physical matter which, as the definition ran, 'neither results from a combination of other physical substances nor is resolvable into such', the conviction arose that man's searching mind had reached 'rock-bottom'. This conviction, however, was shaken when, with the discovery of radium, an element became known whose property it is to disintegrate into two other elements, helium and lead. Although this did not force science to abandon the element-concept altogether, it became necessary to find a new definition for it.
This definition was established by Professor W. Ostwald at the beginning of the present century, when he stated that the chemical element represents a condition of physical matter in which 'any chemical change results in an increase of weight'. In this way, the chemical concept of the element achieved a meaning which had actually been implicit in it from its first conception. For its very formation had been the outcome of the Contra-Levitatem maxim. The following glance over the history of chemistry will show this.
The birth of chemistry as a science, in the modern sense, is closely connected with a revolutionary change in the conception of what can be called the chemical arch-process-combustion, or, to use a more scientific term, oxidation. This change arose out of the Contra-Levitatem maxim and the new conception of heat which this maxim required. In the old doctrine of the four Elements, Heat had been conceived as a manifestation of the element of Fire, and so, together with Air, as belonging to the realm of the 'uncreated things'. Hence the release of heat from created substance was always felt to be a sacred act, as is shown by the fire rites of old.
Modern man's conception of the same process is revealed in the answer one invariably receives from both layman and scientist when they are asked what they understand by combustion. It is described as a process through which oxygen combines with the combustible substance. And yet this side of combustion, first observed by J. Priestley (1771), is neither the one for the sake of which man produces combustion in the service of his everyday life, nor is it at all observed by ordinary sense-perception. Nevertheless, to describe the obvious fact, that combustion is liberation of heat from the combustible substance, will hardly occur to anyone to-day. This shows to what extent even the scientifically untrained consciousness in our time turns instinctively to the tangible or weighable side of nature, so that some effort is required to confess simply to what the eye and the other senses perceive.
During the first hundred years after the establishment of the Contra-Levitatem maxim, man's situation was in a certain sense the opposite of this. Then, people were struggling hard to get away from the old concept which saw in combustion nothing but the liberation of a super-terrestrial element from earthly fetters. This struggle found expression in a theory of heat which at that time greatly occupied scientific thinking. It is the so-called phlogiston-theory first proposed by the chemist Stahl (1660-1734).
This theory reveals the great uncertainty into which man's thinking about the world of the senses had arrived at that time. Clinging to ideas inherited from antiquity, man's consciousness was already so far restricted to the forming of pure matter-bound concepts that he was tempted to conceive heat as a material element. To this heat-substance the name 'phlogiston' was given. At the same time, under the Contra-Levitatem maxim, it was impossible to conceive of substance except as ponderable substance. This led to the conviction that whenever heat appears as a result of some treatment of matter (combustion or friction), the material substance subject to this treatment must lose weight.
The experiments of Lavoisier (1743-94), which he undertook following Priestley's discovery of the role of oxygen in combustion, put an end to this theory. These experiments are rightly regarded as the actual beginning of modern chemistry. In Lavoisier we find an observer of nature who was predominantly interested in what the scales could tell about changes in substances. It was from this aspect that he investigated the process of oxidation. What had already been observed by a few others, though without being taken seriously by them, he found confirmed - that, contrary to the phlogiston - theory, matter does not lose weight through oxidation but gains weight. Further experiments proved beyond doubt that in all chemical reactions the total weight of the components remained constant. However much the substance resulting from the chemical reaction of others might differ from these, its weight always proved to be the same as their total weight. What else could be concluded from the apparent unchangeability of weight throughout all the chemical happenings in nature than that the ponderable world-content was of eternal duration? We see here how much modern chemistry and its concept of the chemical element has been ruled right from the start by the one-sided gravity concept of the onlooker-consciousness.
Together with the overcoming of the fallacy that heat is a ponderable substance (full certainty was indeed established only some time later through the investigations of Davy and Rumford into heat generated by friction) - human thinking was led into a one-sided conception of combustion which was merely the opposite of the one held earlier. Whereas formerly man's mind was pre-eminently occupied by the liberation of the imponderable element through combustion, it now turned entirely to what goes on in the ponderable realm.
As we have seen, one outcome of this one-sided view of combustion was the modern concept of the chemical element. To-day our task is to overcome this concept by taking a step corresponding to the one that led to it, that is, by a study of combustibility which does justice to both sides of the process involved.
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