CHAPTER IX. A SKETCH OF THE ATOMIC THEORY FROM THALES TO SIR ISAAC NEWTON. "For hot, cold, moist, and dry, four champions fierce, OEVAL with the manifestation of the reasoning faculties-that far and pre-historic past of man's development-the constitution of the earth and its different aspects and surroundings would hardly fail to excite the imagination of the denizens of the wilde; and, in the course of time, natural phenomena would offer large discussion to the better endowed of the race. A recognition, however faint, of the external world and its living beings, would gratify the dawning mind, and vie in interest with the contemplation of the gods, whose attributes were not seldom associated with both human and terrestrial agencies. In scanning these agencies endless speculations arose, as fanciful in tone as they were ephemeral in duration; each new thought proving as baffling as its predecessor in the attempted solution of the great problem :-What is the constitution, the ultimate composition, or real nature of matter itself? The bold expounders of the cosmogony undertook an arduous task, and as their efforts to unravel the in L tricacies of nature often failed, they found it convenient to follow the example of the theogonists, and shelter their ignorance under the shadows of the mythological altars of their age and race—an orthodox mode of treating scientific difficulties that is not without its counterpart in the history of the state churches of these latter days. The progress of knowledge might well be dilatory amid the almost impenetrable mists of superstition in the past, when to-day the cry of "more light" is still so audible among the adepts of science; and this, be it remembered, after eighteen centuries of Christian indoctrination, itself ushered into the world upon a large substratum of man's intellectual gains. History has made us cognisant of the varied acquirements of the Eastern nations; of the marvellous skill and aptitude of the Egyptians; of the nobler forms of art, the noblest ever vouchsafed to man, being developed pari passu with the grandly philosophic aims of the Greeks; of the world-wide. dominion and scope of the Romans; of the subtle grasp of the Arabian physicians, and the erudite lore of the schoolmen ; all operating more or less in the direction of enlightenment and civilisation. Yet the science of these modern days culling its data from the great stores of evidence of the past, and favoured by novel experimental appliances and methods of inquiry strictly inductive, can lay claim to little more than a firm step on the threshold of discovery. As of yore, so do enthusiastic minds now look hopefully for still higher revelations in science; and assuredly, if there was ever an epoch in human history marked by bold and progressive lines, and A Sketch of the Atomic Theory. 163 powers to fathom the arcana of the cosmos, it is the present age that has been blessed, beyond all precedent, by discoveries of overpowering brilliancy and magnitude. Man looks upon the Earth, its waters and dry land, and admires its meres, its meadows, and its mountains; he soars for miles in its circumambient air; he mines its superficial crust, and fathoms its ocean depths; and everywhere marks a marvellous diversity of form and substance in the stratified rock, the tidal wave, and transparent ether. His admiration is enhanced by contemplating the myriads of organisms in active life, taking their start from the primitive organic cell that in its timely growth and maturity may become shaped into the umbrageous palm or gnarled oak; or find its nidus in the higher organisation of the chimpanzee or cetacea. Yet the organic and inorganic worlds in all their entirety; the blood and the life thereof, as well as the adamantine conditions of inert matter, when subjected to chemical analysis, become resolved into a few primary or elementary substances. They are designated simple or elementary bodies, because they can be shown to exhibit one kind of ponderable matter only, be it light as air, or heavy as lead; for instance, the gases oxygen and hydrogen, or the metals gold and silver, which the chemist has hitherto failed to resolve into more parts or constituents than one. To-day the chemist assures us of sixty-three elementary bodies—some of them being little heard of, others in vast proportion to the mass; thus four well-known elements in their various compounds, constitute the whole of the organic kingdom-including all living things flourishing on the earth or in the ocean. Reflecting on the mode in which Nature works, and the few agencies she employs in the formation of the most composite of her structures, it is probable that in the course of time these sixty-three elements may be reduced to a smaller compass, and eventually man, by the aid of a higher science, may realise the grand idea of One God-one Law-one Element. This word "element" has been in use for thousands of years, bearing, however, a very different meaning to that attached to the term by modern chemists; thus air, water, fire, and earth, were called elements, and in common parlance to-day we hear of the watery or the fiery elements. Now air and water are not primary or elementary in structure, (though they were viewed as such till about one hundred years ago), but, consisting as they do of two or more gaseous substances, belong to the class of bodies designated composite or compound. The chemist has no faith in substances being deemed elementary till his experiments, or processes of reduction, fail to elicit more than one kind of matter from his analyses. The nature and the number of elementary bodies do not affect this thesis; but rather, having got an unit or element, say oxygen or gold, chlorine or mercury, it behoves us to know the condition of its minutest particle or ultimate form? Is it solid, penetrable, or divisible; and what are its relations and affinities? It is pretty well established, that with the dawn A Sketch of the Atomic Theory. 165 of philosophy among the Greeks, if not dating back to the Egyptians, with whom, as far as this narrative is concerned, the Hindoos and Chinese may be historically bracketed, the higher minds of these respective races were divided in opinion, not only as to the character and import of the visible agencies in the cosmogony, but as to the ultimate and invisible or smallest conceivable particles of matter. And the discussion arising thereon has been continued down to our own day without arriving at a determinate or settled conclusion on the subject. Two theories have long been upheld, and are still current regarding the constitution of matter. 1. According to one class of thinkers, there is no limit to the divisibility of matter, the smallest portion of any substance still consisting of an infinity of parts, which could be rendered distinct if our instruments and senses were capable to the task. 2. The opposing party hold that every material mass in nature is divisible into very minute, indestructible, and unchangeable particles; to which particles the name Atom-a Greek term signifying that which cannot be further cut or divided-has been given. The preponderance of opinion is in favour of this view, or the atomic constitution of bodies. upheld by Dalton, who maintained that all bodies are composed of ultimate atoms, the weight of which is different in different kinds of matter. The ancients meditated much on atoms, the primitive matter or essence of things, mainly, however, from a physical point of view. And though the opinions they advanced were not infrequently shadowed by a fitful intuition, or swayed by a longing to |