Le Roy Clark Cooley

“ It has been said that the science of astronomy is the demonstration of the law of gravitation. Indeed, what evidence have we of the truth of Newton's grand generalization, except that it explains the phenomena of the skies? So, in the outset, we may say that the science of physics is the demonstration of the molecular theory of the constitution of matter, since it explains phenomena, suggests research, directs experiment, classifies and unitizes wide ranges of apparently diverse results, to an extent unparalleled by any other. ”

“ But the physicist does not deny the logic of the metaphysician; he simply remembers that mental conceptions need not of necessity represent the realities of nature's processes, in the subdivision of matter. He claims that the line which may be mentally thrust through the minutest particle of matter is not a needle nor a knife—that it is the mathematician's line as immaterial as space—and that the thrusting of such a line can accomplish no division. ”

“ Even he who has made the circuit of the world can not rely on this extended experience to enable him to see the beginning, middle, and end of 1,000,000 miles in their true proportions. Yet this is a little more than the one-hundredth part of our distance from the sun, from which we get the light and heat on which our lives depend. ”

“ When the idea of a chemical atom came to be clearly conceived so that atom could be defined, as it is, to mean the smallest particle of an elementary substance which can enter into the composition of a compound, the most natural, if not, indeed, the inevitable corollary would be that the compound itself must be made up of parts, each of which, containing only the minimum number of its constituent atoms competent to give it character, must be the smallest particle of that substance which can possibly exist. ”

“ Now, there may be phenomena which declare the existence of molecules without touching the question of molecular space or of molecular motion, and proofs both of the existence of molecules and of molecular spaces may be altogether silent on the question of rest or motion. But notice: whatever evidence we have of the existence of intervals between the ultimate parts of a body is equally evidence of the existence of molecules, and whatever phenomena indicate the existence of motion among these interior parts of a body do equally affirm the existence both of molecules and of molecular spaces. ”

“ We are further informed that the distance from center to center of the molecules of a gas is probably about 1800000 of an inch. Different methods of investigation agree tolerably well in pointing to 130000000 f a millimetre as a fair approximation toward the diameter of a molecule—that is to say, about 760,000,000 of these bodies lying side by side would bridge the space of a single inch.
These magnitudes are of an order which only modern science has ever asked the intellect of man to contemplate. The human mind thus discovers its position between two infinities. ”

“ The atomic theory, revived and vitalized by the illustrious Dalton, has not simply been able to survive the conflicts in which many an older theory has been wrecked: it has itself been a prime mover of revolutions. ”

“ Exposing next the globe to the temperature of boiling water, the liquid will evaporate, and we shall have our vessel filled with ordinary steam. If, now, that cubic foot of space is really packed close with the material which we call water—if there is no break in the continuity of the aqueous mass, we should expect that the vapor would fill the space to the exclusion of everything else, or at least would fill it with a certain degree of energy which must he overcome before any other vapor could be forced in. ”

“ The presence of the steam does not interfere in the least degree with the expansion of liquid alcohol into alcohol-vapor. The only difference which we observe is that the alcohol expands more slowly into the aqueous vapor than it would into a vacuum. If, now that the globe is filled with aqueous vapor and alcohol-vapor at the same time, each acting in all respects as if it occupied the space alone, we add a quantity of ether, we shall have the same phenomena repeated. ”

“ But when we compare this diffusion of the latter with the production and commingling of the former, as shown in the globe experiment, we discover this difference: whereas the molecules of the vapor are driven into mixture by the application of heat, those of the permanent gases spring spontaneously each into the spaces of the other without it. Plainly there exists among the molecules of the gases at low temperature an energy to drive them asunder, such as must be introduced by artificial means among those of vapors to enable them to manifest the same action in the same degree. ”

“ But granting the existence of such evidence to sustain it, neither can be called incredible, however it may transcend our comprehension, for credulity consists, not in believing, but believing without evidence. ”

“ We take a tall and narrow glass jar and fill it so completely with alcohol that the addition of a single drop will endanger an overflow. The jar appears to be full of a perfectly homogeneous liquor. But if a sheet of cotton wool, whose fibers have been previously well loosened, be at hand, fragment after fragment may, with care, be slowly introduced, without causing the overflow of a single drop, until the jar appears to be filled with moistened cotton instead of with alcohol. We have before us the surprising appearance of two bodies filling the same space at the same moment. ”

“ THE idea that matter is an aggregate of minute particles, each of which possesses all the essential properties of the mass, is as old as Democritus, but it was left for the present century to crystallize the conception of the atom in clear and accurate expression. ”

“ It is able, through the agency of the senses, to acquaint itself directly with a very limited range of phenomena, but, planting itself upon this little fragment of solid ground, it reaches into space, and by observations and by computations made upon them becomes acquainted with the infinitely great ”

“ We are therefore entitled to declare that this substance consists of ultimate particles, which can not be divided without changing them into other kinds of matter. These are its molecules. Next, in the light of chemical synthesis, also, we may see the existence of these ultimate particles.
Hydrogen and oxygen are the inevitable constituents of water, and two volumes of hydrogen to one volume of oxygen are the invariable proportions. No human agency can obtain water by combining any other elements, nor by combining these in any other proportions. ”

“ The astronomer contemplates magnitudes and distances and motions expressed by figures of such vast array, that the power of enumeration is almost staggered, and our capacity to comprehend values is altogether overwhelmed by them. ”

“ To comprehend the real magnitude is, in both cases, impossible, and our belief in the existence of either must depend on our faith in the infallibility of mathematical processes and on the observations upon which they are based. ”

“ By this means we obtain a single cylinder of gas, the lower half of which consists of the heavier oxygen, and the upper half of the lighter hydrogen, the two gases being in contact only at their surfaces in the middle of the column. Their relative weights would lead us to expect them to maintain these positions; but the well-known properties of these gases enable us to learn that they do not. Neither one alone is explosive ”

“ Into this globe we will first pour one cubic inch of water, and in order to reduce the conditions to the simplest possible, we will connect the globe with our air-pumps and exhaust the air, although, as it will soon appear, this is not necessary for the success of our experiment. ”