PART I. SECTION I.--THE CONSTITUTION OF THE MATERIAL UNIVERSE. SUMMARY OR ANALYSIS OF THE SECTION. MATTER, or the extended universe, is built up of parts, so extremely minute as to be far beyond direct perception, but which receive the name ATOMS, because there is reason to believe that they have a permanent individuality of character corresponding to the inalienable differences of the simple or elementary bodies. A mutual ATTRACTION, or drawing together, pervades all substance. It is seen most notably in the GRAVITATION, which is exhibited by our earth, and the other orbs of space, and which dictates to them, according to a discovered law, their shape and course. An analogous, if not identical attraction-COHESION gives consistency to smaller masses, and its degrees, depending on the opposing effect of HEATMOTION, correspond to the most obvious division of substances, viz., SOLIDS, LIQUIDS, GASES. Combined with ultimate specialities, it produces the physical qualities described by the names-" Porous," Dense," Crystalline," Amorphous," Hard," Brittle," "Elastic," Malleable," 66 Ductile," " "Pliant," " "Tenacious.” 66 66 66 66 99 66 66 Two allied attractions are also of much importance:-ADHESION, as illustrated by cements, solutions, and alloys; CAPILLARITY, as explaining many phenomena of animal and vegetable life, and of common observation. Lastly, INTERATOMIC (CHEMICAL) ATTRACTION, a most potent agency in the world around us, is more obscure in its action, infinitely diversified and altogether incalculable in its effects, previously to experience. "Matter built up of extremely minute parts." 1. The smallest portion of matter that the human eye can see is really a collection of many minute particles, called atoms or molecules, which may be separated, assorted, 2 Matter built up of Minute Parts. or re-arranged, but which no natural power can in the A solid or liquid may by mechanical or chemical processes be reduced into particles so fine that they are no longer perceptible to the eye. When so reduced that a single particle is only the 500,000th of an inch in diameter, it would be no longer visible under a powerful microscope. A small quantity of mercury shaken in a bottle with strong oil of vitriol is teraporarily split into myriads of minute globules. Mere pressure with the fingers will divide this liquid metal into globules so small that they lose their bright lustre and become grey. When sublimed in a tube some of these have been measured and their lustre and opacity determined, when they did not exceed the 20,000th of an inch in diameter. 2. A piece of gold may be hammered into leaf so thin that a book of the leaves, only an inch thick, would contain 300,000 of them. It would thus take about 1800 of them to make the thickness of ordinary paper. Yet each leaf is so perfect that, when laid on any surface, it gives all the lustre of solid gold. By means of phosphorus placed on a solution of gold, this metal may be reduced to such a state of tenuity that its particles are suspended in water, and they give to the water by their transparency a blue, green, or ruby colour, according to the degree in which they have been split by the action of phosphorus. From the experiments of Faraday it appears that the ruby liquid presents gold in its finest state of division. He estimated that in this state the particles of gold formed only the 500,000th part of the volume of the fluid. If the rays of light from the sun are thrown into this ruby liquid by means of a double convex lens, the minute particles reflect the light and show their presence by the production of a cone of gold in the fluid. Platinum, the heaviest metal we have, can be drawn into wire much finer than the web of the spider. A single grain of it can be drawn into a mile of this wire, and seven ounces of it would reach from London across the Atlantic to New York. Glass, which we usually consider so brittle, may be drawn into thread rivalling silk in softness and beauty. Their Minuteness illustrated. 3 A thread of the finest silk that is used in sewing is not single, but is composed of many hundreds of the threads that the silk-worm spins, which are said to be about the 2000th part of an inch in thickness. Extremely fine as these are, they are not so delicate as the spider's thread, for one-eighth of an ounce of the latter would reach from London to Edinburgh, or 400 miles. One-eighth of a grain of indigo dissolved in sulphuric acid will give a well-marked blue colour to 300 ounces of water. This is in about the proportion of the millionth part of a grain to every drop of water. Müncke calculated the size of the minutest visible particle of indigo from the dilution of a measured quantity of the bluecoloured solution. He estimated it at the five hundred billionth part of a cubic inch ! A grain of musk will scent a room for twenty years. During all that time it must have been sending forth its particles in all directions, and yet it will have lost but very little of its weight. By acute sense of smell the dog detects some material trace of his master as he tracks his footsteps, it may be for miles. Still more minute are the divisions of matter that the microscope has revealed. It shows us that a drop of blood owes its colour to a multitude of very minute bodies (or corpuscles) of a round or egg shape, which float in a colourless liquid called serum. In human blood they vary from the 2000th to the 400oth part of an inch in diameter. The microscope also shows us that a drop of water is a globe, in which thousands of tiny creatures (or animalcules) may live and move and have their being. And yet the water is not composed of living beings; it is made up of two gases, and we may have it without a trace of life. In a single drop some hundreds of these animalcules may have their birth, their food, their home, live their short hour of life, and die. Our mind fails to conceive, and almost to believe, such minute embodiment of life and possibly of pains and pleasures. Nor yet have we reached the minimum of matter. Every addition to our power of vision only unfolds a new part of the same diorama ; and if there be a limit to the subdivision of matter, it lies far beyond the line of our perception. For the smallest animalcule has organs of digestion and circulation necessary to the maintenance of its life. The monas crepusculum, or twilight monad, is considered to be the smallest of all living creatures. The globular body of this carnivorous animalcule sometimes does not exceed the 16,000th part of an inch in diameter 4 Matter Indestructible. "The Minima of Matter." 3. Many have thought that this diminution must of necessity go on for ever, and that there can be no limit to the divisibility of matter. But, besides the destruction of all definite conceptions which this involves, there are many strong reasons, drawn from the most varied phenomena of nature, for believing that every substance is made up of minute masses or molecules, which we are either utterly unable to break up, or which when broken up give two or more molecules quite different from the original. We cannot see or handle a single molecule so as to put this directly to the proof. But the whole science of modern chemistry is founded on the conception of definite ultimate parts, and on the assumption that if any alterations take place in a mass, in precisely the same proportion, whatever quantity of it we try, it must be the result of similar alterations in these little masses or molecules. "Matter imperishable." 4. When, then, we find that all matter is indestructible, and that we can no more put the smallest drop out of existence than we can create it, we have a confirmation of the theory which supposes the ultimate particles to be atomic or indivisible. We may melt gold, and even make it pass into the form of an invisible vapour: but there ends the power of heat, the most potent analyser that we have. The natural conception of what takes place is, that the heat can separate the piece of gold into a vast multitude of minute portions, so that each is free from the company of its fellow, and at liberty to move in any direction; but that neither it, nor any other power we know, is capable of separating the molecules themselves. 5. By a chemical process, we may break up water little by little into two gases-oxygen and hydrogen-which separately bear no resemblance to the compound formed by their union : and, whatever quantity of it we take, we always get eight times the weight of oxygen that we get of hydrogen, though twice the quantity of the latter by bulk. Knowing then that, bulk for bulk, oxygen is sixteen times heavier than hydrogen, we conclude that each ultimate molecule of water is formed of two molecules of hydrogen and one of oxygen. |