comte, auguste - the positive philosophy vol I (другой вариант)

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In regard to method, the inquirers who have devoted themselves to establish the theory have advanced chemical science while appearing to diverge from it; simplifying the vast problem which their successors will solve, and preparing for the disclosure of the great laws of composition and decomposition, which would be undiscoverable amidst the infinity of products, if substances could combine, within certain limits, in all imaginable proportions. Such are the claims of this theory, as to doctrine and to method.

It assumed its existence and present form during the first quarter of this century: and it arose from a phenomenon discovered by Richter, and a speculative discussion established by Berthollet.—During the latter half of the last century, several chemists had observed that, in the mutual decomposition of two neutral salts, the two new salts thus formed are always equally neuter. Bergmann, among others, had steadily and specially dwelt upon this. Yet the fact was neglected or underrated till Richter, at the end of the century, generalized the observation, saw what it imported, and derived from it the fundamental law which bears his name. The law is this: that the ponderable quantities of the different alkalies requisite to neutralize a given weight of any acid are always proportionate to these required for the neutralization of the same weight of every other acid. This is, in fact, evidently the immediate consequence of the maintenance of neutrality after the double decompositiom Such a transformation would appear almost spontaneous if it related to a simpler and more developed science than Chemistry; but amidst its complications and the imperfection of our intellectual habits, the closest deductions are difficult if they have any character of generality, and therefore of abstraction, and this achievement of Richter’s is, in consequence, eminently meritorious, on other grounds than its high utility.—His law, with the complements it has since received, is the original basis of the general doctrine of definite proportions. It exhibited, in the case of a considerable number of compounds, the great end of this doctrine; viz., the assignment to every substance of a certain chemical coefficient, invariable and specific, indicating the proportions in which it can combine with each of those that have been similarly characterized. When it had been determined, by a double series of trials, what was the numerical composition of all the salts that may be formed by any one acid with the different alkalies, and any one alkali with the different acids, Richter’s law enabled us to deduce immediately the proportions relating to all the compounds that can result from the binary combination of these two

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orders of substances. Richter himself brought his discovery up to this result, and prepared (but on a basis of experiment too narrow and imperfect) the first table of what were afterwards called chemical equivalents.

These neutral salts constituted a particular case, which could hardly have led on to a general theory of definite proportions. The idea of perfect neutralization must probably, at all times, have suggested to chemists that of a single proportion, on either side of which the neutrality must be destroyed; and thus the neutral salts were a natural first stage of the general theory; but they could not in themselves involve such a theory. It was Berthollet who extended the consideration of proportions to the whole of chemical phenomena. Some years after Richter’s discovery he established as a fundamental principle, in his “Chemical Statics,” the necessary existence of definite proportions for certain compounds of all orders; and he assigned the essential conditions of this characteristic property, which he attributed to all causes which can release the product of chemical reaction, as it forms, from the ulterior influence of the primitive agents. He thus added to Richter’s restricted case the idea of a great number of cases subjected to the same principle, and able to lead on to its entire generalization. It is assigning much too little honour to Berthollet to recognize only the influence of his controversy with Proust, eminent as was the service rendered by Proust in that conflict, in establishing directly the general principle of determinate and invariable proportions.

Such was the double origin, experimental and speculative, of numerical chemistry. The next development had also a double character, arising from the harmony between the conception of Dr. Dalton and the experimental researches of Berzelius, Gay-Lussac, and Wollaston. The inquiry was in a nascent state when Dalton’s philosophic mind discerned its possible generality. He proposed the great Atomic theory, under which the doctrine of definite proportions was developed to the whole extent that it has reached, and which serves as the basis of its daily application. The general principle of the theory is this: all elementary bodies are conceived of as formed of individual atoms, the different species of which unite, generally by twos, in a small number of groups, constituting compound atoms of the first order, always mechanically indivisible, but thenceforth chemically divisible, and, in their turn, constituting all the other orders of composition by a series of analogous combinations. The principle is in such harmony with scientific conceptions in all departments, that it appeared like a happy generalization of the most fa-

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miliar ideas of scientific men in every province of natural philosophy; and its universal and immediate admission took place as a matter of course.

It was observed by Berzelius that the deduction of the existence of definite proportions from this principle would be illusory if the combinations were not restricted to a very small number of atoms: for other- wise,—if the number was, though limited, very great,—the binary assemblages would be so multiplied that we might as well have combinations in any proportions whatever; and then the atomic theory might almost equally well represent the opposite doctrines of definite and indefinite proportions. Dalton was well aware of this; and the restrictions that he enunciated were presently declared too narrow by his successors, who found that they would not comprehend all existing combinations. His assertion eras, that, in every combination, one of the immediate principles always enters for a single atom, and the other generally for a single atom also, and always for a very small number, rarely exceeding six. Taken with the expansion proposed by his successors, the atomic conception evidently represents the entire doctrine of definite proportions. But it is the theory of successive multiples, derived from the primary doctrine, which especially distinguishes Dr. Dalton’s influencee upon numerical chemistry. From the ground of his doctrine he easily saw that if two substances can combine in various distinct proportions, the ponderable quantities of the one which correspond, in the different compounds, to the same weight in the other, must naturally follow the series of whole numbers, since these compounds will have resulted from the union of one atom of the second substance with one, two, three, etc., of the first: and this constitutes a principal element, then perceived for the first time, of the theory of chemical proportions.

Berzelius followed, with his vast experimental study of the whole of the important points concerned in numerical chemistry, the different parts of which he has done more than any other chemist to develope and systematize. He first perfected Richter’s law, so as to connect it closely with the atomic theory; by which it became susceptible of the extension given to it by Berzelius himself, to all compounds of the second order. But the most important new knowledge has arisen from his numerical study of compounds of the first order. By comparing the composition of the metallic sulphurets and that of the corresponding oxides, he diss overed a law, analogous to Richter’s in regard to the salts. This law,— that the quantity of sulphur of the first is always proportionate to the

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quantity of oxygen combined with a like weight of the base in the second, is now regarded, by induction, as applicable to all the corn pounds of the first order to which the same degree of chemical neutrality is assignable. And again, the luminous series of the analyses of Berzelius have precisely verified in another direction the law of successive multiples dis covered by Dalton in pursuance of his atomic theory.

Gay-Lussac followed, with the valuable numerical analyses he effected by having recourse to gaseous combinations, considered, not as to weight, but to volume. He thus not only verified, in a special manner, the general principle of definite pro portions, but presented it under a newaspect, which, by a wise induction, comprehends all possible cases,— showing that all bodies in a gaseous state combine in invariable and simple numerical relations of volume. An accessory advantage of this achievement was that the specific gravity of the gases might be obtained with a precision often comparable to that of experimental estimate. It is necessary however to warn inquirers not to be led away, in their application of the theory of volumes to substances which have never been vaporized, from the point of view which in Gay-Lussac’s application is equivalent to Dalton’s, as adopted by Berzelius.

The labours of Wollaston bore a great part in establishing the doctrine of definite proportions. I do not refer chiefly to his transformation of the atomic theory into that of chemical equivalents, though it has a more positive character, and tends to restrain the student from wandering after inaccessible objects, to which the first might tempt him, if not judiciously directed. The substitution would be of high value, no doubt, if it were not less a change of conception than an artifice of language Nor have I in view the ingenious expedients by which Wollaston popularized numerical chemistry by rendering its use more clear and convenient. A greater service, in our present view, was his furnishing us with the indispensable complement of Richter’s discovery, by establishing the theory in regard to the acid salts, since extended by analogy to the alkaline salts. The case of the acid salts was perhaps the most unfavourable possible for the ascertainment of the principle of invariable proportions. Wollaston effected the proof in the most satisfactory manner; and this special confirmation of the principle is considered, from its nature, the most decisive of all.

Such has been the logical and historical progress of the researches which have constituted numerical chemistry as it is now. We can represent by an invariable number appropriated to each of the different el-

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ementary bodies their fundamental relations of chemical equivalence. whence by very simple formulas, immediately expressing the laws just indicated, we easily pass to the numerical composition proper to each combination. No further evidence of the truth of the doctrine is needed, than the fact of so many illustrious inquirers having attained the same view by ways which each one opened for himself, and all agreeing as to its positive application to all cases of importance, differing only as to the mode of expression of the results in as far as the atomic theory left it indeterminate, and therefore optional. But we must glance at the difficulties thrown in the way of its application by a consideration of the aggregate of chemical phenomena, in order to form a clear idea of the final improvement of which this doctrine vet stands in need.

Among the points which are beyond dispute, it is, first, evident, and no chemist has ever doubted it, that substances differ as much in the proportion as in the nature of their constituent principles. It is an axiom of chemical philosophy that any change whatever in the numerical composition causes a change in the whole of the specific properties, in a more marked degree as the alteration is greater. Varied and gradual above all others as are the proportions produced by the chemical phenomena proper to living bodies, they afford a striking confirmation to this universal maxim. Therefore, in the lowest stages of chemical analysis, chemists have always endeavoured to assign, as a characteristic property, the proportion of the elements of each substance. as far as was possible: and when this was omitted, it was on the understanding that the proposed combination admitted of only a certain pro. portion; as in the case of the neutral salts.

Again, it has long been acknowledged there always exists, between any two substances, a certain minimum and maximum of reciprocal saturation, beyond or short of which all combination becomes impossible. At the utmost certain variations, themselves restricted, have been supposed procurable. Berthollet established, more directly than any one else, the general and necessary existence of these limits of combina- tion,—one of the principal characters which distinguish it from simple mixture. It is clear that the two extreme degrees of all combination must be subject to special and invariable proportions: and, as all agree in this, Al argument about the opposite doctrines of indefinite and definite proportions is reduced to the question whether the passage from the minimum to the maximum of saturation can be effected gradually and almost imperceptibly, or whether it tales place always abruptly, through a

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small number of well-marked degrees.

Thirdly, the possibility and actual existence of intermediary definite proportions are admitted by all chemists, who can have no other dispute than about the greater or smaller generality of such a property. We have seen that the idea of neutrality must, sooner or later, bring after it that of a determinate and unchangeable proportion; and the gradual development of chemical knowledge has extended this character to more and more varied cases. Berthollet disclosed several other causes of definite proportions, which were entirely misconceived before his time, and which may meet in almost all combinations, modifying certain circumstances of the phenomenon. The precise question now is, therefore, whether, besides these determinate compounds, subject to fixed proportions, within the two limits of possible combination, there does or does not exist, in general, a continuous series of other intermediate compounds of a less marked character; in a word, whether definite proportion constitutes the rule, as is now generally supposed, or, as Berthollet endeavoured to establish, the exception. This is now the only dispute. It is no derogation from the interest of the doctrine of definite proportions to say, as some preceding considerations compel us to do, that the decision of this disputed point is not of the importance commonly supposed. The doctrine has tended to simplify the general problem of chemistry; but it must not be supposed that the solution would have been impossible without this aid:—it would have been simply more difficult and less precise. The eminent chemists who concurred in establishing the doctrine were naturally engrossed by that labour; but their successors, who find numerical chemistry constituted to their hand, must beware of losing sight in it of the true scientific aim of chemistry. They must not linger in this vestibule of the science, to the neglect of the direct construction of Chemistry itself,—an enterprise scarcely begun, and to which it is high time that attention should be once more fully directed.

If we inquire, as we must do, how far the doctrine of definite proportions is irrevocably established, we shall bear in mind that the founders of numerical chemistry have accomplished that chief part which depends on an investigation of all known compounds, leaving only the question whether the doctrine is compatible with certain chemical phenomena, neglected during its formation, and remaining to be since referred to it.

The first general objection relates to the important phenomenon of dissolution, evidently possible in an infinity of different proportions. It

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must be acknowledged that the distinctions between the state of dissolution and that of combination, by which the difficulty has been met, afford little satisfaction. In my opinion the only effectual reply must consist in the extension of the principle of definite proportions to the phenomena of dissolution; and, difficult as it may be to do it, it does not seem to me impossible. The way is by the use of an hypothesis already proposed for other cases in which it might appear less admissible. All the successive degrees of concentration of the liquid must be regarded as simple mixtures of the small number of definite dissolutions which shall have been established, either between themselves or with the dissolvent, in the manner of habitual mixtures of water with alcohol, with sulphuric acid, etc. In any case, the positive verification of this hypothesis must be extremely delicate. Furthermore, to render the study of dissolutions fully rational, in this point of view, it is necessary to combine with it that of other analogous chemical phenomena, relating to the absorption of gases by liquids or by porous solids. All these different modes of molecular union are often energetic enough to resist influences able to destroy certain combine lions, properly so called: why should they not be, like them, subject to the rule of definite proportions, if that rule is truly a fundamental law of nature?

The next case that of various metallic alloys, is very extensive, though more particular. The difficulty lies in the question whether these are cases of combination or of mixture. The state of combination has been taken for granted in the case of alloys; whereas the general application of the principle of numerical chemistry requires that they should be mixtures; while, again, it is difficult to conceive of such a mixture of solids as could resist perturbing influences which would appear to be necessarily destructive; as great changes of temperature, the influence of crystallization, etc. The question can be decided only by a series of special experiments, devised to find the general limits of the permanence of unquestionable mixtures; and the results might be extended to other questions of numerical chemistry, as of certain oxides, on which explanations have been hazarded too freely. When a true chemical theory of mixtures is established on a proper basis of experiment, and we leave off referring to an hypothesis of mixture all cases in which combination seems susceptible of an indeterminate proportion, in order to bring them under the lava of definite proportions, we shall get rid of a formidable objection to the principle of numerical chemistry.

The remaining case constitutes the greatest obstacle of all in the

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way of the generalization of the law of definite proportions: and if it cannot be surmounted, the law sinks to the rank of an empirical rule, fit for nothing more than facilitating a certain order of chemical analyses. I refer to the class, anomalous in this view, of substances called organic. And this is the effect, in fact, of the declaration of the chemists of our time, that organic substances do not come under the principle of definite proportions. It amounts to saying that the law rules all the elements, except oxygen, hydrogen, carbon, and azote. The division between inorganic and organic chemistry is merely scholastic; for all chemistry is, by its nature, homogeneous,—that is, inorganic And thus, if we admit of the enormous exception of the numerical composition of so-called organic substances, the doctrine of definite proportions is overthrown as a rational theory. As it evidently cannot be founded on any a priori considerations, it is only by a strict generality that it can become a rational theory.

If we could not hold at once the grand principle of the dualism which pervades chemistry, and constitutes its homogeneous character, and the doctrine of definite proportions, I should not hesitate to sacrifice the latter: for it is more important for chemical progress to grasp the great principle of systematic dualism, than to advance our investigations by the use of the numerical rule. But there is not, in fact, any incompatibility between these two means of progress: and such a brief sketch of my conception on this subject as my limits allow may show how the doctrine of definite proportions can be duly generalized only by discarding organic chemistry as a separate body of doctrine, and extending the principle of dualism to all organic compounds.

If we are to include all organic compounds under one uniform system of chemistry, properly so called, we must refer to physiology, vegetable and animal, the study of the numerous secondary substances which owe their transient and variable existence to the development of vital phenomena, and which have no scientific interest except under the head of biology. We shall see, under that head, hereafter, what the precise classification is, and all that we have to do with it now is to show that it proceeds from the fundamental distinction between the state of death and that of life. The second, and most extended class of organic substances is chiefly composed of mixtures which, as such, admit of all imaginable proportions, within the limits of vital conditions. As for the substances which exhibit real combinations, we must conceive of them as subject to the law of definite proportions; but the complexity, and yet

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more the instability of such compounds will probably for ever forbid their being, successfully studied under the numerical point of view, which is indeed of very inferior interest in biology.—Even after this clearing of the field, we could not accomplish the desired generalization if we had not taken a new stand with regard to the ternary and quaternary substances contemplated by ordinary chemistry. The rigorous dualism which I have before, and in a higher view, shown to be necessary, seems to supply, naturally and finally, the needs of the doctrine of definite proportions.

As long as chemists persist in regarding organic combinations as ternary and quaternary,—that is, in confounding their elementary with an immediate analysis;—while oxygen, hydrogen, carbon and azote are regarded as immediately united, the compounds from them which must be recognized as distinct, after the severest sifting will be enough to constitute an invincible objection to the principle of a numerical chemistry. But if they become binary compounds of the second, or at most the third order, whose principles are formed by the direct and binary combination of those three or four elements, we find ourselves able to represent all the actual numerical varieties established by an elementary analysis, conceiving, for each degree of combination, a very small number of distinct and entirely definite proportions.—In the ternary case,—appro- priate to compounds of a vegetable origin,—their three elements may be united in three kinds of binary combinations. Combining these again, still employing at once oxygen, hydrogen, and carbon, we have three principal classes of compounds of the second order. But then again, each term of the new compounds really corresponds to two distinct substances: and thus, while admitting only one proportion for the binary composition of these bodies, we have already provided for the numerical composition of twelve substances at present called ternary. But, further, we are compelled to suppose at least three different proportions for each binary combination: one producing perfect neutralization, and the other two the extreme limits of the reciprocal saturation: and chemical analogies indicate a much larger number of compounds. Putting those aside, we have thirty-six compounds, without going beyond the second order, by the lowdown combination of three elements on the principle of dualism. We are also entitled now to conceive of a third possible combination between oxygen and carbon, or between carbon and hydrogen, etc., which already furnish two, after being long supposed to admit of only one. Hence, and in view of all these considerations, we may be

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assured that by dualism we might completely and naturally subject to the law of definite proportions eighty-one compounds of the second order, formed from oxygen, hydrogen, and carbon; and this would unquestionably more than suffice to represent the elementary analysis of all distinct substances in the range of vegetable chemistry.

Passing on to the quaternary case,—characterizing what is called Animal Chemistry,—it seems as if the principal class of compounds of the second order must be more numerous than in the ternary case: but the indispensable condition of employing all the four elements at once restricts the classes to three. But when we examine the terms of the secondary compounds, we find that while two represent only one compound each, a third represents five. Thus, the three pairs of compounds yield fourteen of one proportion, and forty-two of the three proportions indicated in the last case. But applying, at each degree, the rational rule of a triple binary combination, without stopping at the inevitable gaps of our existing chemistry, we find ourselves in possession of ninety-nine compounds of the second order, now regarded as quaternary. This is probably a larger number than a rational analysis of animal substances will be found to require. Moreover, as animal substances have undergone a greater degree of vital elaboration than vegetable matters, it would be philosophical to admit, with respect to them, the possibility of a higher order of composition, such as physiological combinations must eminently tend to realize. On such an hypothesis, without going beyond the third order, we might obtain ten thousand perfectly distinct compounds from these four elements, all formed by an invariable dualism, and strictly subject to the law of definite proportions. It is true, nature would not permit the realization of more than a small part of these speculative combinations; but I have pursued the consequences of my conception to this extreme ideal limit, to show how abundant are the rational resources supplied by this new theory for the generalization of the Ads of numerical chemistry. If this view is not followed up, or some equivalent one proposed, it is evident that we must give up the doctrine of definite proportions as a law of natural philosophy, and return to Berthollet’s theory, merely enlarging the cases of fixed proportions which he admitted. In the present state of the question there is no other choice. But my theory having been, not instituted for this destination, but naturally arrived at by another way, and with higher views, and proceeding from established principles, to meet the needs of chemical philosophy, seems to me to be presumptively entitled to a future, and perhaps speedy realization.

This account of the present aspects of the doctrine of definite pro-