Physical process

“ An essential distinction exists between two stages in the process of advancing our knowledge of the laws of physical phenomena; the first stage consists in observing the relations of phenomena, whether of such as occur in the ordinary course of nature, or of such as are artificially produced in experimental investigations, and in expressing the relations so observed by propositions called formal laws. The second stage consists in reducing the formal laws of an entire class of phenomena to the form of a science; ”

“ It is necessary to study not only the bodies themselves, but also the laws involved in their formation and decay. We should seek to understand what physical forces are operative in each reaction, and in what quantities. No chemical change can occur unattended by the phenomena of either heat, light, or electricity. ”

“ It seeks for the first and best explanation of organic beings in the mere mechanical effects of their surroundings. The physical forces which act upon them from outside—the water or the air that bathes them—the impacts of ethereal undulations in the form of light, the vibrations of matter in contact with them in the form of heat—these are conceived of as the agencies principally concerned. ”

“ Nature strives in the dynamical sphere necessarily to absolute indifference, not by magnetism nor by electricity is represented the totality of the dynamical process, but only by the chemical process. ”

“ But to avoid undue suspension of the argument, I content myself with saying that when the respective effects of gravitation, heat, light, &c., are studied, as well as the respective effects, physical and chemical, of the matters forming the media, water and air, it will be found that while more or less operative on all bodies, each modifies organic bodies to an extent immensely greater than the extent to which it modifies inorganic bodies. ”

“ Having now defined the use of the term force, and shown that forces are correlated which are convertible 44and mutually dependent, we go on to study the evidences of such correlation among the motions of inorganic nature usually called physical forces; and to ask what proof science can furnish us that mechanical motion, heat, light, and electricity are thus mutually convertible. ”

“ It is this process which has enabled the physicist to ascertain the methods of molecular motion which give us light, heat, or electricity, and the range of action and the [425] laws which govern the transfer of energy from one of these modes of motion to another. ”

“ I was simple enough to think that no one who had as much knowledge of physiology as is to be found in an elementary primer, or who had ever heard of the greatest physical generalisation of modern times—the doctrine of the conservation of energy—would dream of doubting my statement ”

“ Every condition of organised forms is due to the external excitation of light and heat, and in the chemical changes which take place, an equivalent of these principles, or powers—it signifies but little according to which view we may regard them—is absorbed, and retained as essential to the condition of the matter formed. ”

“ Every form, whether inorganic or organic, which we can discover within the limits of human search, is composed of atoms, which are capable of assuming, under the influence of certain physical forces, conditions essential to the physical state of that body of which they constitute a part. [1] The known forces, active in pro [Pg 5] ducing these conditions, are modes of motion; gravitation and aggregation, heat, light; and associated with these, actinism or chemical radiation; electricity, under all its conditions, whether static or dynamic ”

“ On the remaining pages of this paper I desire to direct attention to some of the facts connected with the main subject of my present inquiry—the concept force.
Physical forces are distributed by modern science into two classes, molecular and molar forces. Molecular forces are those which determine the internal changes of a body, while molar forces cause the motion of the entire mass. ”

“ The forces, of which light and heat, electricity and magnetism, are different forms, also expend themselves. Then there is a step up by the contribution of what was, to this end, and we have the first organic process, vegetable life and its forces. ”

“ Among the forces which determine the forms of cells, whether they be solitary or arranged in contact with one another, this force of surface-tension is certainly of great, and is probably of paramount importance. But while we shall try to separate out the phenomena which are directly due to it, we must not forget that, in each particular case, the actual conformation which we study may be, and usually is, the more or less complex resultant of surface tension acting together with gravity, mechanical pressure, osmosis, or other physical forces. ”

“ In those hard bodies, indeed, the particles of which are in actual contact, and which are closely united, how is it possible to conceive, that air, cold, or heat, can act upon one of these particles, even exteriorly, without the motion being communicated to those which are most intimate and minute in their union? Without motion, how should we be able to comprehend the manner in which our sense of smelling is affected, by emanations escaping from the most solid bodies, of which all the particles appear to be at perfect rest? ”

“ The second class of powers embraces those which we can account for by the universally-known laws of physics. Among these I reckon the mechanism of motion, and the chemistry of the human body, the source of vegetable life. Vegetation, then, and animal mechanism, thoroughly mingled, form the proper physical life of the human body. ”

“ But, if the knowledge of the chemical and physical properties of the bodies which surround us, as well as our imperfect acquaintance with the less tangible elements, light, electricity, and heat, which mysteriously modify or change their combinations, concur to convince us of the same fact ”

“ If they are material bodies—and heat, for example, is the cause of motion—must not the calorific matter move itself—or if it be not self-moving, by what is it moved? If heat is material, and the primary cause of motion, then matter must have an innate power of moving; it can convert itself into active force, or be at once a cause and an effect, which can scarcely be regarded as a logical deduction.
We move a particle of matter, and heat is manifested; the force being continued, light, electricity, and chemical action result ”

“ Now the state, including the shape or form, of a portion of matter, is the resultant of a number of forces, which represent or symbolise the manifestations of various kinds of energy; and it is obvious, accordingly, that a great part of physical science must be understood or taken for granted as the necessary preliminary to the discussion on which we are engaged. ”

“ The position which I seek to establish in this essay is, that the various imponderable agencies, or the affections of matter which constitute the main objects of experimental physics, viz., heat, light, electricity, magnetism, chemical affinity, and motion, are all correlative, or have a reciprocal dependence;—that neither, taken abstractedly, can be said to be the essential or proximate cause of the others ”

“ If the properties of such a system of bodies are found to correspond to those of gases, an important physical analogy will be established, which may lead to more accurate knowledge of the properties of matter. ”

“ The object of the present paper is, to present in a more systematic form, both these and some other principles, forming part of a science whose subjects are, material bodies and physical phenomena in general, and which it is proposed to call the Science Of Energetics. ”

“ We are compelled to reserve our limited space for those branches of science which we are enabled to connect with the great natural operations constantly going on around us. Many of these more abstruse results will, however, receive some incidental notice when we come to examine the operation of the combined physical forces on matter. ”

“ It is, however, certain that we must regard all manifestations of chemical force as dependent upon some secret principles common to all matter, diffused throughout the universe, but modified by the influences of the known imponderable elements, and by the mechanical force of aggregative attraction. ”

“ The biologist will admit that an organism is a mechanism, and (in so far as its bodily structure is concerned) a material mechanism. All the actions of this structure are therefore mechanical, in the two senses of the term: first, as being the actions of material adjustments; secondly,375 as being movements, and thereby included under the general laws of motion represented in Mechanics; the abstract laws of movement for an organic body are not different from the abstract laws of movement for an inorganic body. ”

“ In the study of the first problem we have reached the general conclusion that the secondary phenomena of life are readily explained by the application of physical and chemical forces acting in the living machine. These secondary phenomena include such processes as the digestion and absorption of food, circulation, respiration, excretion, bodily motion, etc. ”

“ We are asked to consider gravitative energy, heat energy, mechanical energy, chemical energy, and electrical energy. When we inquire what is meant by energy, we are informed that it means ability to do work, and that work is measurable as a pressure into a distance, and is specified as foot-pounds. ”

“ Fourthly, the investigation of the phenomena of life in general, on the assumption that the physical and chemical processes which take place in the living body are of the same order as those which take place out of it; and that whatever energy is exerted in producing such phenomena is derived from the common stock of energy in the universe. ”

“ We conceive an organized body to be one in which the parts are there for the sake of the whole, in a manner different from any mechanical or chemical connexion; we conceive a function to be not merely a process of change, but of change connected with the general vital process. When mechanical or chemical processes occur in the living body, they are instrumental to, and directed by, the peculiar powers of life. ”

“ In these speculations, the force of gravity is resolved into the pressure or impulse of solids or fluids. On the other hand, hypotheses have been propounded, in which the solidity, and other physical qualities of bodies, have been explained by representing the bodies as a collection of points, from which points, repulsive, as well as attractive, forces emanate. ”

“ Not until the necessity arose for distinguishing between different forms of energy, and the conditions for developing them, did it become clear to all that a change in the form of energy implied a change in the form of motion that embodied it. ”

“ I shall in a future occasion describe a different method namely that of electromotive variation for obtaining the response of inorganic matter, and demonstrate the continuity of response in the living and the non-living. ”

“ But the physical phenomena of contraction, expansion, absorption, undulatory and vibratory motions accompanying our sensations of light, heat and sound, as well as many other physical phenomena, all point to the fact that volumes of matter which are apparently continuous are really porous: the molecular structure of perceptible matter is an accepted physical theory ”

“ All molecular energy is in its nature constitutive, formative, or structural. All kinetic energy, or actual motion, represents the progress of morphological action in periodical alternations of advancing and retrograde metamorphosis. ”

“ The professor's contention, stated briefly, was that just as electricity, a force that is invisible and indefinable, is generated by the friction of particles of certain kinds of matter, so life is generated and springs into being when certain other types of matter come together in the right proportions and combinations. ”

“ The mechanical powers, the geometrical figures, the motion and weight of the fluids, and the operations of chemistry, are continually engaged in the support and renewal of the frame; uniting an accumulation of force with a simplicity of operation truly wonderful—all contributing by their million operations to produce that beauty of the outward form which we are now seeking to illustrate. ”

“ That a particular molecular motion does give rise to a state of consciousness is experimentally certain; but the how and why of the process are just as inexplicable as in the case of the communication of kinetic energy by impact. ”

“ An account of the modes in which the force generated in organisms by chemical change, is transformed into other forces, and made to work the various organs that carry on the functions of Life, comes under the head of Organic Physics. ”

“ Finally, organic motion which alone is the last and lowest characteristic of the organic in its lowest stage—in which the process of life properly consists, and in which, therefore, we have to recognize the punctum saliens of the whole question—is only an increase and complication of the merely mechanical motion of the inorganic, likewise explainable by mechanical causes. ”

“ We clearly conceive the manner how, and the conditions by which, motility, this most prominent vital manifestation, constitutes an inherent property of the living substance. Do we as yet comprehend in the same way the intimate modes of activity which constitute the properties appertaining to inorganic substances? Is any kind of those peculiar motions which form the scientific essence of the various forces of inorganic Nature so strictly and deeply intelligible as has now become that specific motion which forms the scientific essence of the force of life? ”