Page:Popular Science Monthly Volume 6.djvu/293

Rh two lines of research converge more and more day by day; in the end they will unite and become one.

To sum up our reasonable expectations, we may hope that before long the chemist, from the composition of any substance, will be able to calculate all of its physical properties—boiling-point, melting-point, specific heat at every temperature, expansibility, density, index of refraction, conductivity for heat and for electricity, and so on to the end. I, for one, do not doubt that the day when this will be possible is approaching more rapidly than the majority of chemists suppose. Until that time arrives chemistry cannot claim the honor of being an exact science. In physics a result is to be accomplished which will be complementary to this. Given the quantitative relations of the forces, we ought to be able, from the properties of any body as regards one force, to compute its properties with regard to all others. Knowing the thermal relations of any substance, for example, we shall eventually be able to calculate at once its optical, electrical, and magnetic properties. These results, to be achieved by physics, can be brought about only in connection with the chemical investigations which this paper is intended to emphasize.

But the future of chemistry does not end with the completion of the researches which we have thus far considered. It is the glory of science that every great achievement only opens the way for still greater achievements lying far beyond. So, when chemistry shall have reached the splendid future which I have ventured to suggest, it will only find itself possessed of materials with which to start for a grander future far away in the dim distance. We may expect that an exact knowledge of the laws governing the physical properties of substances will enable us to foresee just what compounds are possible, and by what reactions they may be obtained. Throughout the science, accurate calculation will be substituted for much abortive experiment, and both time and labor will be saved. The same lines of investigation, prolonged still further, will settle the much-vexed question of the nature of the elements; so that we may hope to know whether they are all but varieties of one or two, or whether they are many and essentially dissimilar. Upon the same experimental basis the truth or falsity of the great atomic theory may rest. Given the knowledge which we may expect to have concerning the physical relations of substance, and we ought to be able to devise many crucial tests for the idea of the atomic constitution of matter. All the great speculative questions of modern chemistry must be eventually fought out upon the battle-field of physics.

Now, having recognized some facts concerning the intellectual future of chemistry, let us inquire what material steps will best lead up to them. What experimental work is most needed to begin with? Plainly, if we are to discover laws connecting the physical properties of compounds with their composition, we must first determine the