even jolt, in passing over to this new line of rails prepared for it. it Taking these two, Matter and Energy, as distinct, let us concentrate for a little upon each of them separately. Let us first turn attention upon MATTER. This form of existence is most easily contemplated, as most directly presenting itself to observation. A piece of metal may best serve for illustration, such as the iron out of which we form so many of our industrial implements. This metal may be mingled through earth or rock; may be held in solution in water, or made to flow out in liquid form from the furnace; it may be hardened either in the more brittle form of cast iron, or in the more rigid form known as malleable; but through all these changes the material is the same. Further, suppose we were to receive a quantity of ore, and for the sake of experiment were to have part presented in each one of these forms, the quantity would continue exactly the same as was originally received. To quote again from the same author:-"The grand test of the reality of what we call Matter, the proof that it has an objective existence, is its indestructibility and uncreatability—if the term may be used—by any process at the command of man. The value of this test to modern chemistry can scarcely be estimated. In fact we can barely believe that there could have existed an exact science of chemistry had it not been for the early recognition of this property of matter; nor in fact would there be the possibility of a chemical analysis, supposing that we had not the assurance by enormously extended series of previous experiments, that no portion of matter, however small, goes out of existence, or comes into existence in any operation whatever. If the chemist were not certain that at the end of his operations, provided he has taken care to admit nothing and to let nothing escape, the contents of his vessels must be precisely the same in quantity as at the beginning of the experiment, there could be no such thing as chemical analysis.”* If now we press our inquiry further, seeking some explanation of the ultimate nature. or structure of matter, that is, the common physical characteristics of matter in all its forms, whether air, water, or solid mass, science has no certain answer to give. There is * Recent Advances in Physical Science, p. 14. no theory of the ultimate structure of matter which has secured general acceptance. On the contrary, there is the acknowledgment that the complexity of the problem is so great as completely to baffle the present resources of science. There have been discussions, and careful investigations as to the divisibility of matter, and it has been generally admitted on rational grounds, that there must be in all matter particles or atoms so minute as to be quite beyond the range of the microscope. This has led to the acceptance of an atomic theory as in one form or another applicable to the structure of matter, belief in such particles or molecules being a natural result of scientific procedure. I say belief, for the existence of such ultimate atoms is not established on experimental evidence, and yet is generally acknowledged; for it is clearly enough recognized that there is a region of faith for science, as for theology, just as there must be for all ordinary exercise of human intelligence. Besides the actual divisibility of matter, we have in the same connection to consider its compressibility, for the recognized facts as to compression of iron, for example, or of any metal, seem to imply that there are certain particles related to each other, which can be pressed in upon each other, or brought into nearer proximity. There is, however, a clear limit to compressibility, as there is to divisibility of matter. Even if this be granted, however, we are still without a scientific account of the ultimate structure of matter. This is still a perplexity to be handed on to future workers. There may, indeed, seem to be promise of aid in the analysis of different forms of matter, as in the reduction of water to its constituent gases by the action of a galvanic battery; but such processes, however rich in suggestiveness, are insufficient to advance the main inquiry. It is oftentimes in this very class of experiments, that science at once manifests its power, and discovers the limits which encircle and restrain its efforts. It can decompose, what it can not recompose, thus leaving difficulties as perplexing as before. And besides, even when by analysis the ultimate parts or chemical constituents, of compound substances have been discovered, science is unable to demonstrate that the constituent elements are ultimately composed of distinct atoms, as for example that oxygen and hydrogen are so constituted. We are thus without a science of the ultimate nature of matter. There is, indeed, the suggestion of Sir William Thomson that matter of all kinds may be regarded as of a common nature, only variously compounded, filling space in a fluid state, and that its compressibility can be accounted for on the supposition that its ultimate forms are vortex rings capable of compression and expansion like an india-rubber ball; but this can not be regarded otherwise than as a bold conjecture, beset with a host of difficulties both physical and mathematical which neither Thomson nor any of his fellow-workers in physical science, professes to have yet grappled with. There are thus before us the chief results of physical science, as to the nature of MATTER, when we specify that it is indestructible, that it consists of ultimate molecules or atoms, and that its compressibility is to be explained by pressure upon such atoms, or cohesion, or comparative closeness of relation between them, this being greater in solids, less in liquids, and least in gases. From the structure of matter, we are led by science to the consideration of ENERGY, as distinct from matter. These two stand in |