Popular Science Monthly/Volume 6/January 1875/The Future of Chemistry
By F. W. CLARKE,
PROFESSOR OF PHYSICS AND CHEMISTRY IN THE UNIVERSITY OF CINCINNATI.
EVERY science seems to have, as a science, its most rapid and brilliant growth during the earlier portions of its history. By this I do not intend to say that the mere bulk of its material increases more swiftly than at a later period, when the number of its students and investigators has become great. I mean simply that important generalizations are more readily made and more frequent, and that abstract conceptions are more speedily fertile in results. The reason for this is very obvious. At first, when any new science has but just assumed definite shape, every student has it before his mind as a unit. All parts of the field are immediately under his eye; no portion of it can easily escape notice. Thus it is studied, not less in its details, but more as a definite, consistent whole; and its growth is consistent, well-balanced, and harmonious. When, however, the field becomes larger, there is a splitting up into specialties, and, in general, each specialty is cultivated by some assiduous worker who cares but little for the character which the science may take in its entirety. In other words, the greater the mass of scientific material, the greater is the tendency among investigators to study details at the expense of generalities. Accordingly, the details multiply and become unmanageable; complexity increases, and symmetrical development comes comparatively to a stand-still.
This is emphatically true of chemistry at the present day. Only a very few chemists now study their science as a grand unit. We have technical chemists, agricultural chemists, analytical chemists, physiological chemists, and so on. Each one devotes himself to his specialty almost without reference to the others. What relation his particular branch may bear to the complete science is hardly thought of. Such questions are left to speculators and dreamers. Among those who study the abstract science, without reference to its practical applications, it is much the same. One man has all he can do to examine the derivatives of a single organic group. If he can obtain fifty new compounds in which the interlinking of the atoms may be represented in some unheard-of way, his ambition is satisfied. He chlorinates this body, and deoxidizes that; he makes numberless substitutions, all of which he knew beforehand to be possible; but what, in the end, does it amount to? In Germany, where nine-tenths of the chemists seem to be running wild over the so-called "aromatic group," this multiplication of new bodies is going on with unparalleled rapidity. And yet not one in five hundred of the substances discovered gets thoroughly described. This naphthaline derivative is a solid, with a certain odor, color, melting-point, and crystalline form; and there the description ends. No thought of ascertaining its other physical properties ever seems to enter the head of the discoverer. Doubtless all this work has a value; some of it has already led to results of great importance; still it is not in any such direction that chemistry is to look for its chief future growth. The same amount of effort, otherwise expended, would yield much richer returns. Unfortunately, an inferior line of research has become fashionable, and scientific investigators, like all other people, are more or less subject to fashion. It must be plain to every one, however, that the work of chemistry amounts to a good deal more than merely to obtain, formulate, and classify new compounds. It is necessary to study not only the bodies themselves, but also the laws involved in their formation and decay. We should seek to understand what physical forces are operative in each reaction, and in what quantities. No chemical change can occur unattended by the phenomena of either heat, light, or electricity. To-day, little is done save to investigate the results of chemical reactions. Surely the phenomena of the reactions themselves ought to be studied a little more. Chemistry would not lose much were no new compounds to be described for ten years to come, if chemists might only be induced to examine more closely the substances already known.
These few words of well-meant criticism may very properly lead us to the main subject of this paper: What is the future of chemistry? In what direction must the science look for its grandest development? What grand generalizations may we expect, and what steps should be taken to lead up to them? As the past is always prophetic of the future, it is evident that we must pay some attention to the former growth of chemistry before we can safely predict what is to come. If we would be thorough, we ought to do even more, and extend our view across the limits of this particular science into the fields of other sciences closely connected with it. For present purposes, however, we need consider, in conjunction with chemistry, only its twin-sister, physics. The two sciences are so closely intertwined that neither can be studied alone. Progress in either, in the long-run, means progress in both. Upon the border-land between the two our attention must be fixed.
Upon studying the history of chemistry, we cannot but be struck by the changes which have occurred both in the form and in the significance of chemical notation. There we have to deal with a symbolism so peculiar that it represents in its modern form several very important stages of scientific growth. Every great change in chemical thought is mirrored by some modification in this symbolic system. At first a formula represented the composition by weight of a substance, and embodied certain theoretical conceptions with which we have, for present purposes, nothing to do. Soon an extension of our knowledge so modified the notation of chemistry that the new formulæ, though differing but slightly from the old, represented more than composition by weight, namely, composition by volume also. Still later came the attempt, now being vigorously continued, to make every formula represent not only ultimate composition by weight and by volume, but also the probable arrangement of the atoms within the molecule. In other words, if we ignore the atomic hypothesis, a modern chemical formula aims to express some of the more important chemical relations and reactions of the body represented. In close connection with these purely chemical discoveries, we find a little physical work. Thanks to Kopp, we are able to calculate from the formula of almost any liquid its atomic volume, and thence its specific gravity at the boiling-point. Other investigators enable us to calculate the indices of refraction for different liquids, and, to a more limited extent, some other physical properties also. In short, a system of notation, originally based upon the properties of the atoms as regards weight, has been found to express also many of their other physical relations; and the list of facts thus expressed is continually lengthening. Evidently, then, the tendency of chemical investigation is to connect the physical properties of every substance directly with its composition.
Here we step over the border into physics. Plainly, if we have to deal with physical properties, we must study the forces represented by them. And, fortunately for the chemist, the tendency among physicists is entirely in his favor. Growing up contemporaneously with the development of chemical notation, we have had the grand ideas of the conservation of energy and the correlation of forces. We have learned that force is one, indestructible and uncreatable, and that all its manifestations are mutually convertible one into another. Either of the great modes of force may be active in affecting chemical composition; may cause chemical union or chemical separation; may be the motive of either analysis or synthesis. Now, in the direction here suggested, the main work of physics is being done. The chief object of the physicist to-day is to determine quantitatively the relations connecting all the different varieties of energy. Under what circumstances, and how, are forces transformed? Since these transformations are differently effected through the intervention of different forms of matter, it is clear that the physicist must take into account the chemical composition of the materials with which he deals. In short, then, the chemist must look to physics for a knowledge of the forces involved in chemical changes; while, on the other hand, the science of physics must needs throw from chemistry its information upon the nature of all the material agencies through which the transformations of force become apparent. Neither physics nor chemistry can work independently of the other; the more closely they become allied in the labor of investigation, the more rapidly will both progress. The 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 physical properties of the elements. This work should be done with the greatest care and thoroughness. Every element should have its relations to the forces of Nature thoroughly fixed and tabulated. Even the rarest elements ought not to be neglected, since each one has its scientific importance, fills a place in some series or groups, and, for purposes of generalization, is of as great interest as any other. But, as it is to-day, the commonest substances have been very imperfectly studied. Only a few constants have been determined for some of the most familiar elements, the gases especially. Just enough is known about the commoner metals to show us how ignorant we really are. Here, then, is a great field for work, and in it some of the richest materials for both chemistry and physics are to be gathered. It is, indeed, strange that this work, obviously of such vast importance, should have been so long postponed. Of course no single individual could undertake it, but it seems as if some learned society, or even some government, might assume the burden! A twentieth part of the money expended for the determination of one astronomical constant, the earth's distance from the sun, ought to cover all the expenses of the undertaking. If we had in America a laboratory exclusively devoted to research, suitably manned and equipped, our country might carry off the glory of achieving this grand work. In default of such a laboratory, however, the labor might be accomplished through the cooperation of many individual workers, each one doing his small part, not aimlessly, but in unison with the others. One chemist might undertake to furnish certain of the elements in a perfectly pure condition; another might carefully determine under varying circumstances their densities and rates of expansion; a third could work up their specific and latent heats; a fourth their electrical relations, and so on. Failure to attain grand results would be impossible. Doubtless the labor would prove irksome and monotonous, but the reward would be sure. In five years, more would be done toward rendering chemistry an exact science, than can be accomplished in a century by means of the chemical investigations at present most in vogue.
The physical properties of the elements being established, the next thing is to do somewhat similar work for compounds. And here, before entering on experimental labors, it is necessary to know what has already been done. This knowledge is at present difficult to obtain, since the materials are scattered through many pages of many volumes of scientific transactions and periodicals, and need to be collected and systematically arranged. This work of tabulation having been finished, chemists will be able to see distinctly where experiment is most needed, what must be done entirely new, and what ought to be done over again. Then, some of the experimental details might be easily intrusted by professors to the hands of students. If, for practice, a student is taking specific gravities, let him work upon substances for which that constant has never been determined. So also with such other physical measurements as naturally come up in a college laboratory. The student would be getting his instruction at the same time that he felt himself interested in aiding science, and both he and science would be gainers. The material so collected might hardly be of the highest accuracy, but it would certainly not be quite without scientific value. Any one, who will examine the nature of the material already on hand, will forcibly realize this fact.
It would be easy to multiply suggestions. Any chemist, who will carefully survey the field, will be surprised at the immense amount of obviously important work which has hitherto been left undone, and which should take precedence of nearly all the chemical investigations now most in fashion. The necessity of this work is based upon no wild speculations, but upon a foundation of the most severely practical ideas. No extraordinary difficulties hedge it about, no real impracticabilities stand in the way. Certain great laws ought to be discovered, and they can be discovered only by means of researches such as are here suggested. A few years of steady, earnest work upon the part of fifty scientific chemists would accomplish all the chief results which I have ventured to prophesy.