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Position And Method Of Chemistry

( Originally Published 1913 )

WE have still to occupy ourselves with the general considerations forming the prolegomena to Chemistry, and notably with its position in the hierarchy of the sciences, and its Method.

We may make this capital distinction between Physics and Chemistry : In Physics (celestial and terrestrial) we study the laws of motion communicated; in Chemistry (inorganic and organic) the laws of motion excited. In purely physical phenomena we see a force communicated from one body to another ; but in chemical phenomena we see a force combining with another force to excite a change in the phenomena of both, the result of which is unlike either.

I content myself with indicating this distinction, and turn to Comte for further light as to the position of Chemistry in the scientific hierarchy. The position he assigns to it seems to him a good illustration of the fact that his classification does not rest on arbitrary assumptions, but is in truth the faithful resumé of the points of harmony inherent in the sciences, and manifested naturally by their common development. No one, indeed, of the positions in the encyclopedical scale seems so naturally and so appropriately occupied as that of Chemistry between Physics and Physiology. Who could now fail to see that, in several essential parts, and above all in the important series of electro chemical phenomena, Chemistry is in immediate contact with the ensemble of Physics, of which, in appearance, it constitutes a simple prolongation; and, again, that at its other extremity it is in some sort connected, by the no less fundamental study of organic combinations, with general Physiology, of which it establishes, so to speak, the primary foundations ? These relations are so very close that, in more than one particular case, Chemists who had not mastered the true philosophy of the sciences could not venture to decide whether the subject really fell within their province, or whether it belonged to Physics or Physiology.

Chemical are more complex than physical phenomena, and less general. We have physical without chemical effects, but no chemical effects unaccompanied with coexistent physical. Hence, too, Chemistry is indirectly subordinated to Astronomy, and even to Mathematics. As far as respects doctrine, the connection is indeed small. Chemical questions cannot be treated among mathematical doctrines ; and in abstract Chemistry there is little reference to Astronomy. In concrete Chemistry, i. e. in the application of chemical knowledge to the natural history of the globe, the connection between Astronomy and Chemistry is much more apparent. As respects Method, Mathematics and Astronomy have had a great influence on the cultivation of Chemistry. From the study of mathematical phenomena have been obtained habits of rationality, precision, and consistency. Although mathematics are less needful to the chemist than to the natural philosopher, the evil effects of the want of those habits, owing to a defective mathematical education, may be seen in most chemical speculations. Astronomy being the great type of scientific perfection, its influence is the more needed in Chemistry, because the phenomena are increased in complexity. Astronomy is calculated, much more than this was true when Comte wrote, in 1838 but now chemical questions are beginning to be susceptible of purely mathematical treatment.

Physics, to show Chemists the radical inanity of all metaphysical explanations, and to make manifest the true characteristics of their science. Comte also shows here, but more fully in his lecture on Physiology, how that science must be based upon and follow in the wake of Chemistry. He next proceeds to estimate the general perfection of chemical science, as respects method and doctrine.

As to Method, physical philosophy has approximated much nearer than chemical philosophy to the complete state of positivity. If the first still presents, with respect to the theory of hypotheses, a quasi-metaphysical character, there is no exaggeration in saying that the second continues in some respects essentially metaphysical in spirit, by reason of its more difficult and more tardy, development. The doctrine of affinities, although now rapidly losing its hold, is even more ontological than that of the fluids and imaginary ethers. If the electrical fluid and the luminous ether are really nothing but materialized entities; are these affinities anything else than pure entities, as vague and indetermined as those which flourished in the scholastic philosophy of the middle ages ? The pretended solutions which we have been in the habit of deducing from them, evidently possess the essential characteristic of metaphysical explanations the simple and naive reproduction, in abstract terms, of the very statement of the phenomenon. The accelerated development of chemical observations during the last fifty years, which will doubtless soon discredit for ever this false philosophy, has hitherto only modified it in such a way as to show its radical nullity with irresistible evidence. When affinities were regarded as absolute and invariable, their employment in the explanation of phenomena, although of necessity always illusory, had at least a more imposing appearance. But since facts have compelled us to conceive affinities as, on the contrary, eminently variable and dependent upon a multitude of different circumstances, their use could no longer be continued, without speedily becoming, by this single change, more plainly futile and almost childish. Thus, for example, it was known for a long time that at a certain temperature iron decomposed water or protoxide of hydrogen ; and yet it was after-wards discovered that, under the mere influence of a higher temperature, hydrogen in its turn decomposed oxide of iron. What, then, can signify the order of affinity which we believed we had established between iron and hydrogen towards oxygen ?

The state of education at the time explains how men of genius like Berthollet could entertain such notions as that of elective affinities. It is to those metaphysical habits that we owe the doctrine of predisposing affinity, employed even by the great Berzelius. For example, when sulphuric acid determines the decomposition of water by iron, at ordinary temperatures, so as to disengage hydrogen, the metaphysical explanation of the process is that sulphuric acid has an affinity for oxide of iron, which tends to form itself. Observe, the oxide of iron does not as yet exist it exists only after the decomposition has taken place ; so that on this doctrine of affinity we have the sympathetic action of one substance upon another substance not yet in existence, but called into existence by this sympathetic action ! Even Liebig, who repudiates the notion of affinity as expressive of anything like relationship, has not emancipated himself sufficiently from the metaphysical condition to give up the notion of an inherent tendency.

As another example of metaphysical Chemistry, consider the favourite notion of a catalytic force. The following passage, from Gregory's admirable Handbook of Organic Chemistry, expresses my views with authority " The view adopted by Berzelius, according to which fermentation, and all the other phenomena of chemical change produced by contact, are the results of a peculiar unknown force, the catalytic force, coming into action when certain bodies are placed in contact, appears unphilosophical, as in the first place, assuming the existence of a new force where known forces would suffice to explain the facts ; and, secondly, as furnishing no real explanation, but merely acknowledging, indirectly, our inability to offer any such explanation. When we ascribe an effect to catalysis, we are only saying, in other words, that we cannot account for it ; catalysis is thus merely a convenient term for all that we do not understand. And to the use of the word in this sense, namely, as a name for the agent which produces certain effects, the agent itself being unknown, there would be no objection, were it not that catalysis has been employed to account for phenomena not only different from each other, but actually of an opposite kind. For example, platinum, in causing the combination of oxygen and hydrogen, is said to act catalytically, and the action of oxide of manganese, or oxide of silver, in decomposing peroxide of hydrogen, that is, in causing the separation of oxygen and hydrogen, is also called catalytic. This example proves how loosely the word has been employed, and how vague are the views which have led to its introduction."

In accordance with the position of chemistry in a scientific hierarchy, the general plan of rational education for a chemist requires a preliminary study of mathematical philosophy, next of astronomical philosophy, and last of physics. We should remember, when speculating philosophically on this subject, that this doctrine of affinities is only an attempt (necessarily a vain one) to conceive the hidden nature of chemical phenomena, which is as radically inaccessible as the analogous essences men sought in former times to discover, by similar processes, in the case of more simple phenomena. And how can the chemist aid in ridding his science of these metaphysical ideas, without first mastering the more simple and now more positive sciences ? How, if half metaphysical as regards them, can he be positive in chemistry ? Must not the individual, like the species, in its gradual development, extract positive conceptions from the simpler sciences first?

In respect of doctrine, chemistry is also inferior to physics. Chemical effects are still essentially incoherent, or at least feebly coordinated by a small number of partial and insufficient relations, in place of those laws, as certain as they are extensive and uniform, which are justly the glory of physics. As to prevision, the true measure of the perfection of each natural science, it is too evident that if it is already much more limited, more uncertain, and less precise in physics than in astronomy, the case is still worse with Chemistry. Most frequently, the issue of any chemical action can only be known by taking express account of the circumstances of the moment, and, as it were, at the time the action is ended.

Let us now glance at the most distinguished of the philosophical properties of Chemistry, with reference to their direct bearing upon the fundamental education of humanity.

On this point, and in the first place, as to Method, Comte refers to the high philosophical utility of the arts of experiment and observation as practised in Chemistry. But there also exists in the system of positive method a very important part, too little appreciated as yet, and which Chemistry had the special function of bringing to the highest degree of perfection. Comte does not here speak of the theory of classifications (sufficiently ill understood by chemists), but of the general art of rational Nomenclatures, which is altogether independent of it, and of which Chemistry, by the very nature of its subject, must present more perfect models than any other fundamental science.

Attempts have often been made, especially since t he reform of chemical language, and they are still daily made, to form a systematic nomenclature in Anatomy, in Pathology, and especially in Zoology. But whatever may be the real utility of these praiseworthy efforts, they have not, and never could have been, followed by a success like that of the illustrious founders of chemical nomenclature, even if they were better conceived and more rationally directed than they have hitherto been ; for the nature of the phenomena peremptorily forbids it. It is not accidentally that chemical nomenclature is so perfect compared with all the others. In proportion as the phenomena increase in complexity, the objects are characterized by points of comparison at once more varied and less circumscribed. It consequently becomes more and more difficult to subject them in a manner sufficiently expressive to a uniform system of denominations, rational and at the same time abridged, and to have this system adapted really to facilitate the habitual combination of ideas. Were it that the organs and tissues of living bodies only differed among themselves in one single and capital point of view, that diseases were sufficiently defined by their seat, that zoological genera, or at least families, could be always formed on one principle completely homogeneous, then we might conceive that the sciences would immediately allow of systematic nomenclatures as rational and as efficacious as that of chemistry. But, in reality, the profound diversity of the numerous aspects under which they present themselves, and which are almost never susceptible of being coordinated uniquely under one of them, evidently renders our arriving at such perfection both very difficult and little advantageous.

Among the sciences in which the immense multitude of subjects spontaneously give rise, at their formation, to special nomenclatures, Chemistry is the only one where, from its nature, the phenomena are sufficiently simple and uniform, and at the same time sufficiently determined, to permit of a nomenclature at once clear, rapid, and complete, and thereby contributing to the general progress of the science. The direct and ruling idea in chemistry is incontestably that of composition; and the peculiar object of the science is to make all chemical questions resolve themselves into one of composition. Hence, since the systematic name of each body would make its composition directly known to us, it can easily give us a general but correct notion of the ensemble of its chemical history; and afterwards serve to us as a faithful and concise summary of that ensemble ; and from the very nature of the science, the nearer it advances towards its final destination, the more will this double property of its nomenclature be inevitably developed.

Thus Chemistry must be considered as eminently suited to develope, in the most special manner, one of those fundamental means of obtaining and using knowledge (so few in number) which together constitute the general power of the human mind. Comte has endeavoured to show very clearly the principal causes of the evident superiority which results from the very nature of chemical science. But although he required to do so, it is incontestable that the formation of systems of rational nomenclatures in the more complex sciences must possess a real and engrossing interest, notwithstanding that they are necessarily more difficult to establish there, and less efficacious in their use. He desires to make clear the indispensable necessity of every class whatever of positive philosophers having recourse exclusively to chemistry for extracting the true principles and general spirit of the art of scientific nomenclatures. This is just in accordance with that fundamental rule, already carried out in so many other respects, in the Cours de Philosophie Positive—viz. what each logical artifice ought to be directly studied in that part of natural philosophy which offers the most spontaneous and most complete development of it, with the ultimate object of our being able to apply it, with proper modifications, to make more perfect the other sciences.

The eminent philosophical properties of Chemistry are still more remarkable in respect of Doctrine than of Method. Its development has contributed much to the emancipation of human reason from theological and metaphysical doctrines. If Chemistry, from increase of complexity, is defective in one of the two attributes which tend to that emancipation namely, prevision of phenomena, it is—as a necessary and compensating consequence of the same fact strikingly provided with the other—namely, the power of modifying them at our pleasure. Neither can co-exist with the idea of a government by providential volitions.

Besides, Chemistry has aided in emancipating the human mind, by rectifying our primitive notions respecting the general economy of terrestrial nature. Although, since Aristotle, philosophers entertained the notion that the same elementary substances essentially reproduced themselves in all the great operations of nature, notwithstanding their apparent independence ; nevertheless, it necessarily resulted from the utter impossibility of realizing this vague and metaphysical anticipation of the truth, that the universal dominion of the theological dogma of absolute destruction and creation kept its hold until the great epoch of that admirable development of chemical genius which forms the principal scientific characteristic of the last quarter of the eighteenth century. In fact, so long as we could take no account of gases, either as the elements or the products cf chemical action, a great number of remarkable phenomena inevitably encouraged the belief in the annihilation or the actual production of matter in the general system of nature. Certain discoveries were requisite to establish beyond cavil the fundamental principle of the necessarily indefinite perpetuity of all matter ; such, especially, were the decomposition of air and water, and afterwards the elementary analysis of vegetable and animal substances, and perhaps, too, at a later period, as the complement of those, the analysis of alkalies properly so called, and of earths. The tendency of those discoveries was irrevocably to substitute in all minds the positive notions of decomposition and re composition, for the theological notions of destruction and of creation. A new light, also, was thereby thrown on vital phenomena. It was perceived that organic and inorganic matter were not radically different ; and that vital transformations are, like all others, subordinated to chemical phenomena.

Comte concludes the chapter with some remarks respecting the divisions of chemistry. The science, he says, is still too much in its infancy, and too imperfect, to offer, of itself, a proper division. The homogeneity of its phenomena, so exceptional when contrasted with other sciences, makes a natural division of it little marked. It is clear, however, that in the meantime the division of chemistry into inorganic and organic, must be disregarded, as being irrational. Combinations cannot be classified in abstract chemistry according to their origin, as they may be in natural history. The two classes referred to are always mutually encroaching on each other. In reality, what is called organic chemistry is half chemical, half physiological.

Any rational division must be founded on the principle involved in the true definition of the science that of composition and decomposition. Hence, in here applying the rule of always following the gradual complication of the phenomena, we see that, in dividing chemistry into its principal branches, we can be guided by only these two considerations.

1st. The increase of the number of the constituent compounds (whether mediate or immediate), according as the combinations formed by them are either binary or ternary, &c.

2nd. The degree of composition, lower or higher, of the immediate compounds, each of which, to take for example the case of a repeated dualism, can be decomposed a greater or less number of times into two others.

It may be questioned which of these two points of view ought to preponderate. According to Comte, the chief consideration belongs to the degree of composition, as it is a matter of more importance in the science than the multiplicity of the constituent compounds.

Having closed the general considerations, he proceeds in subsequent lectures to treat of Inorganic Chemistry in general, and of the doctrine of Definite Proportions, and the Electro-chemical theory in particular. In these lectures, the student will, of course, note many details which in so rapidly advancing a science as Chemistry have assumed a new aspect since 1838, when the lectures were published; but the philosophy of Chemistry he will there find set forth in large outlines.

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