Works of Grant Allen, page 788
Winds and storms act in similar ways. They all arise from some kind of separation, produced in air or water by heat; or from the subsequent cooling of the heated masses. In the first case, we see the absorption of separative Power; in the second case the re-establishment of equilibrium on its disengagement. They, too, act as Liberating Energies for the Potential Energy of masses elevated above the general gravitative level, as when they blow down trees, walls, or stones, and beat the waves against a cliff. In one way or another, every Energy which falls upon our earth from the sun is employed in wearing down all inequalities of surface, — that is, in liberating masses possessed of Potential Energy, and permitting them to obey their gravitative impulses.
The special case of lightning demands a brief explanation. Throughout, we have dealt lightly with electrical phenomena, and we must do so here once more. The Potential Energy of the separative electricities in the thunder-cloud and the earth is in some way a product of solar Energy. So long as they remain apart, there is some kind of statical separation between unknown units generally aggregated. At last, some Liberating Energy in the shape of wind or heat brings the charged masses within range of their mutual affinities. At once a discharge takes place, and the Potential Energy is liberated as Light, Heat, and Sound; all of which are finally turned loose upon the ether as radiant Energy, to pulse perhaps for ever, through the interstellar spaces. The only peculiarity of the case is the conspicuous and instantaneous way in which the Potential Energy is liberated and assumes the Kinetic Mode.
So, too, with many human machines. Organic phenomena will demand careful separate treatment; and until this has been given we cannot properly understand such a case as that of a steam-engine, where the prime Energy is derived from organic products like coal and wood. But certain simpler machines like water-mills and windmills may conveniently be explained at the present stage. The water which falls from clouds on an elevated patch of ground still possesses Potential Energy in virtue of its separation from the general gravitative level, and as the force of gravitation is very little interfered with by cohesion in the case of liquids, the water is enabled to form into a stream, and run down to the sea. On the way, under ordinary circumstances, it parts with most of its Potential Energy by friction, or yields it up in falling as heat. But where a considerable fall occurs, it is possible to employ this energy in turning a wheel. The wheel, being connected with other wheels and grindstones, gives up the Kinetic Energy thus derived, partly in producing separation, in opposition to cohesion, among the molecules of corn, and partly in heat or friction. The heat is of course radiated off, and the rest of the Energy remains Potential in the flour. So also with a windmill. Here the Kinetic Energy of wind, itself derived from solar rays, is transferred to the vans of the mill, and is finally used up in producing separation in the corn, or in heating the bearings and grindstones. In both cases we see, as usual, an intermediate employment of Energy for the purpose of separating material particles, but a final loss of energy from matter to the ethereal medium.
In all these cases we deal with phenomena essentially unconnected with organic life: for although the machines mentioned above are of human construction, yet, when once set in action, they can go on without human intervention until the loss sustained by friction makes their working impossible. In the next chapter we shall consider the more involved case of living organisms. Before doing so, however, it will be well to sum up the conclusions at which we have arrived regarding the general dynamical phenomena of our planet.
The earth is a proximately spherical mass of matter, held together by its own gravitation, and bulging slightly towards its equator, where its axial Energy produces the greatest effect. It revolves round the sun in virtue of its orbital motion, and it possesses Potential Energy by reason of its separate condition. This Potential Energy, however, cannot assume the Kinetic Mode, because the solar gravitation is opposed by the orbital Energy of the planet. Though the earth thus possesses two proper molar motions of its own — the axial and the orbital — its Molecular Energy has been radiated away into space from the surface at least, only the interior portion being still in a highly heated state. The interference of cohesion in this outer solid shell with the general gravitation whose Force comes into free play as the internal mass cools and contracts, gives rise to a state of tension, finally resulting in cracks and corrugations on the surface. If no external Energy intervened, the outer shell would present one uniform cold and probably solid surface, broken up into ice-clad mountains and valleys. But a fraction of the Energy radiated into space by the aggregating masses of the central sun falls on the outer shell and there interferes with the aggregative process by setting up temporary separative action among the less coherent molecules. It keeps the atmosphere and the ocean in the gaseous and liquid forms respectively. It produces such an expansion of the equatorial air as gives rise to monsoons; and elsewhere it heats the atmosphere of deserts, valleys, and low-lying plains so as to cause local winds and storms. It also lifts up great masses of water, which float in the air as clouds, and finally fall as rain when their Energy is dissipated. It heats the equatorial oceans, and thus rendering them lighter sets up warm ocean currents, while gravitation, drawing down the colder masses, produces the compensating cold streams. The separative nature of all these processes will be obvious when we reflect that every one of them depends upon such an absorption of radiant heat as overcomes the aggregative Force of cohesion. But these changes are never permanent. The Energy thus absorbed is soon radiated off to the cooler ether in those less energetic periods which we know as night and winter. Unless every day and every summer new Energy were poured upon the earth to set up similar separative actions, the effects of each Energy-absorbing period would soon pass away. The vapour and the water would part with their heat, condense, and finally freeze: while the air would cool down, settle into stable equilibrium, and perhaps aggregate at last into the solid state. Moreover, the Energy which thus falls upon the earth acts indirectly as a liberating agent to those more solid masses which are prevented by cohesion from aggregating in the stablest possible manner with the general body of the planet. By wearing down mountain sides; by water-action, percolation, glacier-grinding, and attrition of rolling bodies; by blowing over stones, chimneys, and trees; by wasting cliffs, headlands, and river-banks; by grinding down pebbles, shells and refuse; and by depositing all the débris thus resulting in new and lower strata of mud and sand — by all these ways and countless others, to which every gorge, ravine, denudation valley, and seaward cliff bears witness, the Energy poured down upon us from the sun acts as a liberating agency to reduce the inequalities of our planet’s surface, and bring every body ultimately into closer and more intimate aggregation with the general mass.
Thus we see that on the surface of our earth the universal process of aggregation continues in spite of partial interruptions. Incident Energy let loose from the aggregating sun produces local and temporary separations among its material particles; but such separations do not interfere in the end with the general aggregating process, which they rather indirectly assist. As elsewhere, we find all the matter engaged in a continuous course of aggregation, and all the Energy thus liberated continuously handed over to the ethereal medium.
CHAPTER V.
ORGANIC LIFE.
The interferences caused by incident solar Energy in the aggregative processes of our earth which were considered in the last chapter mostly consisted in separative actions opposed to the molecular Force of cohesion, and, less directly, to the molar Force of gravitation. Those phenomena which we have to consider in the present chapter are the result of interferences by solar Energy opposed to the atomic Force of Chemical Affinity.
It is not here asserted that all the cases where solar Energy interferes with and opposes Chemical Affinity are concerned with vital phenomena. But vital phenomena form the principal instance of such interferences, and all the others may be omitted as illustrating no new principle and suggesting no new difficulty.
Regarded in their naked dynamical aspect these phenomena may be briefly described as follows. The incident solar Energy, — besides falling upon molecules in the slightly aggregated cohesive states which we know as the liquid and the gaseous, and overcoming their very moderate cohesion so as to produce evaporation and expansion — also falls upon certain atoms aggregated together by the Force of Chemical Affinity, and sets up in them separative actions, which result in the severance of these atoms from their affinities, and the rebuilding of some among them into those peculiar forms which may be described as Energetic Compounds (hydrocarbons, &c.), while the remainder are cast in a free state upon the atmosphere. The radiant Energy thus employed is used up for the time being in producing these separations, and is retained partly by the freed elements, and partly by the Energetic Compounds, either in the Potential Mode or in the Kinetic, or partly in one and partly in the other (for on this point we have as yet no certain knowledge). The Energy thus absorbed by the Energetic Compounds apparently remains within them permanently, until some incident Energy, acting as a liberating agent, causes their atoms once more to unite with those other free atoms in the atmosphere for which they have affinities. When they reunite, all the Energy which was absorbed in producing their separation is liberated once more by the act of aggregation, and is yielded up to the ether as low-grade Energy. While the Energy is retained by the freed element and the Energetic Compound we may either suppose that it is all Potential and consists merely in the statical separation of their atoms, — on which supposition it will be exactly analogous to the case of a rock, raised to a height and then supported so that it cannot fall without the intervention of a liberating Energy: or we may suppose that it is partly Potential and partly Kinetic, and consists not only in the statical separation of the atoms, but also in a relative motion of the atoms in the Energetic Compound, — on which supposition it would be analogous to the case where a collection of bodies like the solar system, having relative motions of their own, possess Potential Energy with reference to some other external body, like the star in Hercules, towards which the solar system is supposed to be moving. It is clear that on the first supposition the amount of Energy liberated by the reaggregation of the atoms will be equivalent to the Potential Energy of their statical separation: but on the second supposition the amount liberated will be equivalent to that Potential Energy, plus the Kinetic Energy of the relative motions possessed by the several atoms — just as, if the sun were to aggregate with any fixed star after all his planets had already dissipated the Kinetic Energy of their several orbital motions, and united with his mass, the Energy liberated by the aggregation would be the equivalent of the statical separation previously existing between the sun and that star; whereas, if the aggregation were to take place to-day, the amount of Energy liberated would be equivalent to the statical separation of the two systems, plus the Energy liberated by the stoppage of orbital and axial motion in each of the planets and satellites. It is not improbable that, in certain instances at least, we may be induced to accept the second of these two suppositions.
Translated into concrete language, the above abstract propositions may thus be more simply expressed. Solar Energy falls upon a crust containing the molecules of water, carbonic anhydride, the various nitrates in a state of solution, and other raw materials of organic matter. It finds their atoms in a condition of relatively stable chemical combination — in other words, closely bound up with one another by the Force of Chemical Affinity. Being absorbed by some or all of these atoms, it sets them free from their stable unions, by producing motions which take them beyond the sphere of their mutual attractions. It leaves the oxygen of the carbonic anhydride in a free state, while it builds up the carbon with the hydrogen of water into certain Energetic Compounds, such as starches, &c. The Energy of these compounds may be all Potential — that is to say, may consist in the fact of their statical separation from the attracting oxygen and their loose chemical apposition; or it may be partly Kinetic as well — that is to say, may also consist in the fact that the various atoms have relative movements like those of a planetary system. Furthermore, in the case of the Energetic nitrogenous compounds there is reason to suppose that a suppressed Energy is also involved. Once these Energetic Compounds have been built up, they remain permanently inert, retaining their Energy themselves in a dormant state — at least so far as human observation can detect — until some Liberating Energy brings them once more under the influence of Chemical Affinity. Thus a piece of wood or a lump of fat, once produced, remains inert, at least to outward appearance, so long as it is kept at a low temperature and isolated from disintegrating agents. But so soon as we apply a certain degree of heat to either, they burn away; or, in other words, unite once more with the oxygen from which they were previously separated, and yield up as they aggregate all the Energy of their separation and their relative movement (if any) in the form of Light and Heat. Moreover, there are several ways in which such a liberating agency can be set in action. It may be by human aid, and the intervention of external burning matters, as when we light a piece of wood or a candle by means of a match. Or it may be by the intervention of some animal organism, as when a worm burrows into a piece of wood and uses up its Potential Energy in the performance of his physiological functions, by causing its atoms to combine with oxygen within his body: or as when a carnivorous animal devours the fat, and so employs it in his physiological functions: or as when the animal which has deposited it, himself employs it for his own use, which case we see illustrated in the bear and other hibernating animals. Or, again, it may be by the set of external liberating agents which produce what we call decomposition: as when a tree decays slowly where it fell, under the influence of moisture and gentle heat: or when a dead animal decomposes in the sunlight: — though these latter cases are sure to be accompanied by the development of other organisms, which act as liberating agents, such as fungi, maggots, vibrios, and other like organisms. But whatever may be the means by which is brought about this recombination of the organic substances with the oxygen previously liberated from their affinity by solar Energy, there are two points which can be laid down as certain. First, that no such reaggregation of the separated atoms can take place without the intervention of a liberating agent, whether that liberating agent be moisture, solar light and heat, animal germs, fungus spores, or human interference: as we clearly see in the fact that to preserve an organic substance we may either desiccate it, or freeze it, or seclude it from light and heat, or from animal and vegetable germs, or secure it from being devoured by some other organism, or from the interference of human beings, who might burn it or otherwise cause its reaggregation with oxygen: while on the contrary we know that exposure to one or other of these liberating agents will bring about such reaggregation (or decomposition, as it is oftener though less accurately called) in every kind of organic matter. Second, that on the whole and in the vast majority of cases almost every piece of organic matter aggregates at last with the oxygen or other free atoms from which its elements were at first severed, and yields up its Energy to the ether in some more or less conspicuous manner. Thus, sooner or later, every plant, if left to itself, dies and decays: that is, recombines with oxygen slowly, under the influence of moisture, light, and heat, and yields up its Energy by inconspicuous degrees; while every animal, if left to itself, similarly dies and decays, probably under the influence of other small animal germs, which use up its contained Energies in carrying on their own activities: and so, in both these cases, the atoms finally reaggregate in stable combination, while the Energy is yielded up, immediately perhaps to surrounding matter, but finally to the ethereal medium. So, too, if the plant or animal is devoured by an animal organism, its atoms are made to combine with oxygen within the devouring organism, and their Energy is yielded up as heat and as movement, either of internal parts or of external limbs, and is thus finally dissipated. And even if, as in the case of peat, petroleum, and coal, or of the Siberian mammoths, the Energetic Compounds are long secluded by their circumstances from Liberating Energies, it may yet finally happen that human activity may intervene to liberate their Energies, as we see when we burn coal, petroleum, or peat, or when we exhume mammoths, and so expose them to the decomposing (liberating) action of the sun and organic germs. So that organic life, when closely considered, proves dynamically to be a mere special case of the general laws: and we see that though it is in its nature separative, as being the product of solar Energy absorbed for a time by particular mundane particles, it nevertheless results in a final reaggregation of atoms in stable combination, and dissipation of Energy to the ethereal medium.
