It was pointed out by Newlands that atomicity and other properties of some of the chemical elements depend on the order in which their atomic weights succeeded one another; and when this law was extended by Professor Mendelejeff to all elements it was apparent that a mathematical relation exists between the elements. This far-reaching law has been fruitful of results. Referring to Professor Reynolds’s diagram illustrating the law, Mr. Crookes says: “The more I study the arrangement of this zigzag curve, the more I am convinced that he who grasps the key will be permitted to unlock some of the deepest mysteries of creation. Let us imagine if it is possible to get a glimpse of a few of the secrets here hidden. Let us picture the very beginnings of time, before geological ages, before the earth was thrown off from the central nucleus of molten fluid, before even the sun himself had consolidated from the original protyle.[[74]] Let us still imagine that at this primal stage all was in an ultra-gaseous state, at a temperature inconceivably hotter than anything now existing in the visible universe; so high, indeed, that the chemical atoms could not yet have been formed, being still far above their dissociation-point. In so far as protyle is capable of radiating or reflecting light, this vast sea of incandescent mist, to an astronomer in a distant star, might have appeared as a nebula, showing in the spectroscope a few isolated lines, forecasts of hydrogen, carbon, and nitrogen spectra.
“But in course of time some process akin to cooling, probably internal, reduces the temperature of the cosmic protyle to a point at which the first step in granulation takes place; matter as we know it comes into existence, and atoms are formed. As soon as an atom is formed out of protyle it is a store of energy, potential (from its tendency to coalesce with other atoms by gravitation or chemically) and kinetic (from its internal motions). To obtain this energy, the neighbouring protyle must be refrigerated by it, and thereby the subsequent formation of other atoms will be accelerated. But with atomic matter the various forms of energy which require matter to render them evident begin to act; and, amongst others, that form of energy which has for one of its factors what we now call atomic weight. Let us assume that the elementary protyle contains within itself the potentiality of every possible combining proportion or atomic weight. Let it be granted that the whole of our known elements were not at this epoch simultaneously created. The easiest formed element, the one most nearly allied to the protyle in simplicity, is first born. Hydrogen—or shall we say helium?—of all the known elements the one of simplest structure and lowest atomic weight, is the first to come into being. For some time hydrogen would be the only form of matter (as we know it) in existence, and between hydrogen and the next formed element there would be a considerable gap in time, during the latter part of which the element next in order of simplicity would be slowly approaching its birth-point: pending this period we may suppose that the evolutionary process, which soon was to determine the birth of a new element, would also determine its atomic weight, its affinities, and its chemical position.”
Professor F. W. Clarke on the pre-nebular condition of matter.—Views on elemental evolution almost similar to those of Mr. Crookes’s have been advocated by Professor Clarke. Spectroscopic phenomena, says Professor Clarke, are quite in harmony with the idea that all matter is at bottom one, our supposed atoms being really various aggregations of the same fundamental unit.
“Everybody knows that the nebular hypothesis, as it is to-day, draws its strongest support from spectroscopic facts. There shine the nebulæ in the heavens, and the spectroscope tells us what they really are, namely, vast clouds of incandescent gas, mainly, if not entirely, hydrogen and nitrogen. If we attempt to trace the chain of evolution through which our planet is supposed to have grown, we shall find the sky is full of intermediate forms. The nebulæ themselves appear to be in various stages of development; the fixed stars or suns differ widely in chemical constitution and in temperature; our earth is most complex of all. There are no ‘missing links’ such as the zoologist longs to discover when he tries to explain the origin of species. First, we have a nebula containing little more than hydrogen, then a very hot star with calcium, magnesium, and one or two other metals added; next comes a cooler sun in which free hydrogen is missing, but whose chemical complexity is much increased; at last we reach the true planets with their multitudes of material forms. Could there well be a more straightforward story? Could the unity of creation receive a much more ringing emphasis? We see the evolution of planets from nebulæ still going on, and parallel with it an evolution of higher from lower kinds of matter.
“Just here, perhaps, is the key to the whole subject. If the elements are all in essence one, how could their many forms originate save by a process of evolution upward? How could their numerous relations with each other, and their regular serial arrangements into groups, be better explained? In this, as in other problems, the hypothesis of evolution is the simplest, most natural, and best in accordance with facts.”[[75]]
Dr. G. Johnstone Stoney on the pre-nebular condition of matter.—Further evidence that all the chemical elements were probably evolved from one common source, is furnished by Dr. G. Johnstone Stoney’s “Logarithmic Law of Atomic Weights,” a theory recently advanced in a communication to the Royal Society.[[76]] A cardinal feature of this investigation is that in it atomic weights are represented by volumes, not by lines. A succession of spheres are taken whose volumes are proportional to the atomic weights, and which may be called the atomic spheres. When the radii of these spheres are plotted down on a diagram as ordinates, and a series of integers as abscissas, the general form of the logarithmic curve becomes apparent; and close scrutiny has shown that either the logarithmic curve, or some curve lying very close to it, expresses the real law of nature.
If, as seems probable, the logarithmic law is the law of nature, there appear to be three elements lighter than hydrogen, which Dr. Stoney has termed infra-fluorine, infra-oxygen, and infra-nitrogen. And there are, at all events, six missing elements between hydrogen and lithium.
Dr. Stoney’s investigation is based on the fact that if the atomic weights of the chemical elements be arranged in order of magnitude, periodic laws come to light, viz.: those discovered by Newlands, Mendelejeff, and Meyer. From this it follows that there must be some law connecting the atomic weights with the successive terms of a numerical series—either alone or along with other variables.
“This law,” says Dr. Stoney, “may be obtained in one of its graphical forms by plotting down a series of integers as abscissas, and the successive atomic weights as ordinates. In this way it furnishes a diagram which has somewhat the shape of a hurling-stick, consisting of a short curved portion succeeded by a long and nearly straight portion. But as this diagram cannot be directly identified with any known curve, it does not suffice for the determination of the law.
“The diagram, however, assumes a form which can be interpreted when we use the cube roots of the atomic weights for its ordinates, instead of the atomic weights themselves. This is equivalent to taking volumes instead of lines to represent the atomic weights. When this is done, the ends of the ordinates are found to lie near a regular and gradual curve, from which they deviate to the right and left by displacements that are small and appear to follow periodic laws which have been in part traced. The central curve is found on examination to be either a logarithmic curve or some curve lying exceedingly close to it. If the curve be in reality the logarithmic curve, it furnishes us the law that: