thermological effects. We are less cautious at the present day: we confound the auxiliary, or the general physical agent of the jjhenonienon, with the phenomenon itself, and pervert chemistry by confounding it with electrology, by irrationally assimilating chemical to electrical properties, as is seen especially in the theory of M. Berzelius. How can there be any scientific comparison between the tendency of two bodies to a mechanical adhesion after a certain mode of electrization, and the disposition to unite all their molecules, external and internal, by a true chemical action? M. Berzelius has frankly declared that cohesion, properly so called, admits of no electric explanation. Nothing is gained towards explaining the molecular connection, indissoluble by any mechanical force, in contrast with the magnetic union so easily overcome, by talking of voltaic elements with their positive or negative pole, and their connection by the electric antagonism of the opposite poles.
Such inventions give no idea whatever of molecular cohesion. Nor is affinity, or the tendency to combination, any better explained by the electro-chemical theory. Electrical phenomena, in physics, are eminently general, offering only differences of intensity in different bodies; whereas, chemical phenomena are essentially special or elective: and therefore every attempt to make chemistry, as a whole, enter into any branch of physics, is thoroughly antiscientific. This would be enough: but we see besides that the smallest changes in the mode of electrization reverse the electric antagonism, and destroy the proposed electrical order of elementary bodies: we find ourselves \anable to deduce the new electric properties which the theory bids us look for in the compounds of different orders; we do not know by what laws they derive their positive or negative character from the electric condition of each of the two elements; nor are we able to approach the great end of chemical science, — the prevision of the qualities of compounds by those of their constituent elements. Moreover, in any case, the great body of chemical phenomena opposes insurmountable obstacles; as when oxygen, the most negative element, when entering largely into certain oxides, finds them positive towai'ds certain acids, into which it enters much more sparingly, — the radicals of the first bein^ often as negative as those of the last. According to M. Berzelins's own frank declaration, organic compounds cast insuperable difficulties in the way of his arrangement of electric relations; and he alleges the transience of the combinations in that class of cases as an explanation of the anomaly: but chemical science would be impossible if compounds were not throughout considered stable till causes of decomposition arise: and if organic compounds are guarded from these, they remain chemically stable, like inorganic substances. The fundamental obstacle of the whole case, — the identity of the elements, in opposition to the electric variety, — cannot by any means whatever be got over.
Leaving all these difficulties on one side, we learn nothing about chemical phenomena by likening them to electrify action, for we establish thus no harmony between the pretended causes and the real eifects. Every attempt seems to prove simply the auxiliary influence of electricity on chemical effects, — acting as heat does, only with a different intensity. In fact, there are scarcely any electro-chemical combinations which caimot be effected by ordinary chemical processes, without any electric indications; and the few exceptional cases still existing may, by analogy, be expected to be brought under the rule. If, in the face of all this, we were to persist in investing the electrical influence with the specific and molecular attributes of chemistry, we shovild merely be restoring the old entity of affinity, decked out with some hypothetical material attributes, which would be far from rendering it more positive: and such a procedure would be as hurtful to jjhysics as to chemistry, by infusing new vagueness into our notions of electricity, which are at present far from being sufficiently distinct.
And then might follow, as likely as not, the founding on electrology, not only the whole of chemistry, but the theories of heat, of weight, and probably, as a consequence, that of celestial mechanics. And then, if we added to this heterogeneous assemblage a confounding of the supposed nervous fluid with the pretended electric fluid, we should have attained to the show of an universal system, devoid of all scientific use, which would fall to pieces as soon as tested by real study, parting off into RESULTS OF THE THEORY. 373 categories of independent doctrine, and encumbering natural philosophy with insoluble questions, which must be discarded, to enable us to begin afresh.
Thus, to sum up, the great chemical influence of electricity, like that of weight, and yet more of heat, is unquestionable; and I have endeavoured to exhibit the high imjiortance of electro-chemistry to the improvement of chemical science, of which it is one of the essential elements. But I must, once for all, reject the conception through which it has been attempted to transform all chemical into electrical phenomena. In a philosophical point of view, Lavoisier's theory appears to me, notwithstanding its serious imperfections, very superior as a scientific composition to that to which it has given j^lace. It related directly to the aim of chemical science, — the establishment of general laws of composition and decomposition; whereas the newer theory draws attenticm away from it, in a vain inquiry into the intimate nature of chemical phenomena. Thus the anti-phlogistic conception has suggested numerous and important chemical discoveries, while it is very doubtful whether as much will ever be said for the electric theory. In an indii-ect way however it may operate favourably for..
chemical science, by its binary antagonism amUKnvers^ suggesting the extension of dualism among compounds which are as yet supposed to be more than binary. Berzelius appears to have felt this connection; and he would probably have erected dualism into a fundamental principle, but for his subjection to the old division of chemistry into organic and inorganic. Others, who are free from this entanglement, may be prepared by the electro-chemical theory for general dualism; though it is not, in principle, desirable to recur to faulty means to attain good results in an indirect way. In another view, this theory may be useful, — in fixing the attention of chemists on the influence of time in the production of chemical effects; — an influence remarkably manifested by many phenomena, but not, as yet, directly analysed. Not only does time naturally increase the mass of the products of chemical re-action; it also causes formations which would not otherwise exist. The chemical theory of time is at present a blank in science; and the phenomena of electro-chemistry seem likely to enlighten us on this head, ■ — so all-imjiortant in its connection with chemical geology, while constituting an indispensable element in the conceptions of abstract chemistry.
To complete our survey of the |>hilosophy of Chemistry, we must turn to some considerations already suggested, on the subject of what is commonly called Organic Chemistry.
ORGANIC CHEMISTRY.
ORGANIC Chemistry comprehends, it cannot be denied, two kinds of researches, chemical and physiological, which are perfectly distinct. For instance, the study of organic acids, and especially the vegetable Confusion of acids, and alcohol, ethers, etc., has a character two kinds of as purely chemical as that of any inorganic *^^*-substances whatever; and, on the other hand, there is no doubt of the biological character of inquiries into the composition of sap or blood, and of the analysis of the products of respiration, and many other matters included in organic chemistry. The confusion of the two orders is prejudicial to both sciences, and especially to physiology. The division of Chemistry conceals or violates essential analogies, and hinders the extension of dualism into the organic region, where it is seldom found, though, as I have shown, it is optional, in fact, throughout the whole range of chemistry; and thus the arbitraiy arrangement is the chief obstacle in the way of the entire generalization of the doctrine of definite proportions. And whenever a true chemical theory shall fitly replace the anti-phlogistic conception, it must necessarily comprehend all organic, as well as inorganic compounds. The most philosophical chemists are tending more and more to a recognition of the identity of the two departments; and there can be no doubt that the establishment of that identity will be an immediate conseqxience of a rational classification of chemical knowledge.
The confusion is more mischievous, but less felt by chemists, under the other view, — the comprehension of biological phenomena among those of organic chemistry. The confusion arose from the need of chemical researches in very many physiological questions; and these chemical researches, being usually extensive and difiicult, were out of the range of the jihysiologists, aucl were taken possession of by the chemists, who annexed them to their own domain. Both classes were to blame for the vicious arrangement, and both must amend their scientific habits before a division can be effected in entire conformity to natural analogies. The physiologists have the most difficult task before them, having to qualify themselves for inquiries from which the chemists have only to abstain.
It is scarcely possible to characterize or to circumscribe the physiological part of organic chemistry, formed as it is by successive encroachments. It comjirehends the chemical analysis of all the anatomical elements, solid or fluid, and that of the ^ro(^Mc/s of the organism; and if its usurpations remained unchecked, it would soon include the phenomena of Avhat Bichat called the organic life; that is, the functions of nutrition and secretion, the only ones comiuon to all living bodies, and in which the chemical point of view might well appear the natural one. In such a state of" things, physiology would be reduced to the study of the functions of animal life, and to that of the development of the livingbeing. It is easy to see what would become of biological science, if it were reduced to this fragmentary state.
Chemists cannot but be unfit for the rational examination of the important questions of anatomy and physiology, vegetable and animal, because the research requires that comprehension of view which their studies, as chemists, preclude them from obtaining. In the anatomical relation, they are perpetually overlooking the fundamental division, established by M. de Blainville, between the true elements of the organism, and its simple products; and they take for one another, almost indifferently, the tissues, the parenchyma, and the organs. The spirit of biological investigation being unknown to them, they can neither choose their subject well, nor direct their analysis wisely. If these are grave inconveniences in anatomical questions, they are much more serious in physiological problems, properly so called, the essential conditions of which are not understood by chemists. The rational direction of physiological analysis can take place only by the subordination of the chemical to the physiological view; and therefore by the employment of chemistry by the physiologists themselves, as a simple RELATION OF CHEMISTRY TO AXATOMY. 377 means of investigation. It is an analogous case to that before exhibited, of the application of mathematical analysis to physical questions. If it is important that physicists should emj)loy the instrument of analysis, instead of delivering over physical subjects to the mathematicians, to be a mere theme for analytical exercises, much more important is it that the greater diversity of view in chemistry and physiology should not be lost sight of. The irrational and incoherent studies comprised in the organic chemistry of our day give us no idea of the true nature of the aids that biology may derive from chemistry. A few instances will show the high im]>ortance of an improved organization of scientific labour.
In the anatomical order, almost all the re- Kelatiou of searches of chemists have to undergo an Chemistry to entire revision by the physiologists, before Anatomy, they can be applied to the studies of the elements or the products of the organism. The fine series of researches of M. Chevreul on fatty bodies are ])erhaps the only important chemical study immediately applicable to biology, animal or even vegetable. In the chemical analysis of blood or sap, or almost any other element, a single case, taken at hazard, is usually presented as a satisfactory type, without any comparative investigation either of each species of organism in its normal state, or of the degree of development of the living being, — its sex, its temperament, its mode of alimentation, the system of its exterior conditions of existence, etc., and other modifications which physiologists alone can duly estimate. Such analyses correspond to nothing in anatomy but the single case observed; and even that is seldom sufficiently characterized. Hence inevitable divergences among chemists, who choose different types, and discussions of no scientific use, as the discordance is attributed to the diiferent analytical methods employed, instead of to the variations which physiology would have led them to anticipate. The case is the same with regard to products first secreted and then excreted, as bile, saliva, etc., which offer a still greater complication. The chemists make no incpiiry about the parts from which these products are taken, or the modifications which may have been occasioned by their remaining some time after their production, etc.; and therefore the analyses of these products, however often renewed, are still incoherent and thoroughly defective. We owe to M. Raspail a full exposure of the practice of the chemists of multiplying oi'ganic principles almost without limit, from differences of character which imply no distinction of nature, but are merely marks of various degrees of elaboration of the same principle in different developments of vegetation; and even from confounding the observed substances with their anatomical envelope. It is to be regretted that M. Easj^ail did not complete his great service to science by founding rationally the physiological portion of organic chemistry, instead of vainly attempting to systematize organic chemistry, under the bias of our crude chemical education.
rp pj.• 1 „, If we turn from the anatomical order of ''" ' questions to the jDhysiological, we shall find yet stronger evidences of the inaptitude of chemists for biological inquiries. All endeavours have yet failed to establish any point of general doctrine in biology; and we find ourselves merely with simple materials, which must be newly elaborated by physiologists, under the view of vitality, before they can be put to use. To give an example or two: — the experiments of Priestley, Sennebier, Saussure, and others, on the mutual chemical action of vegetables and atmospheric air, were of the highest value, as instituting positive knowledge of the vegetable economy; but the inquiry is by no means so simple as its founders naturally supposed, after having analysed one separate portion of the phenomenon of vegetation. The absor2:)tion of carbonic acid, and the exhalation of oxygen, though very important in relation to the action of leaves, are only one aspect of the double vital motion, and cannot be understood but in the physiological view of both. This action cannot explain the elementary composition of vegetable substances, or determine the kind of alteration sustained by the air through vegetation, because it is, in other ways, partially compensated by the precisely inverse action produced by the germination of seeds, the ripening of friiits, etc., and even, as regards the leaves, by the mere passages from light to darkness. It is much to have indicated the true nature of the requisite research, and to have supplied some RELATION TO PHYSIOLOGY. 379 materials for it. The rest is the business of the the physiologists. If we turn to animal physiology for examples, the case is yet more striking.
After all the inquiry that has been made into the chemical phenomena of respiration, no fixed point is yet established. It was long supposed that the absorption by the lungs of atmospheric oxygen, and its transformation into carbonic acid, would exj^lain the great phenomenon of the conversion of venous into arterial blood. But the problem is much more complicated than was supposed by the chemists who established this essential part of the phenomenon, and whose labours present the most contradictory conclusions in regard to the facts under their notice. We do not know, for instance, whether the quantity of carbonic acid formed really corresponds to the quantity of oxygen absoi'bed; and even the simple general difference between the inhaled and exhaled air, which is the first point to be ascertained, is far from being positively established. The atmospheric azote appears to some to be increased after respii*ation, while others say it is diminished, and others again that it remains the same. The disagreements about the changes in the composition of the blood are yet more marked. Perhaps the inaptitude of chemists and physicists for physiological researches is more striking still in the case of animal heat. In the early days of modern chemistry, this phenomenon seemed to be sufficiently accounted for by the disengagement of heat corresponding to the decarbonizing of the blood in the lungs, which the chemists regarded as the focus of a real combustion; but this explanation was soon found to be inadequate, even in a normal condition; and much more in various pathological cases. Uncertain as we still are as to the pulmonary influence in the process, we know that all the vital functions must concur in it, in a greater or smaller degree. There is even some reason to suppose, in direct opposition to the opinion of the chemists, that respiration, far from aiding to produce animal heat, constantly tends to diminish it. No doubt, the chemical effects occasioned by vital action must always be taken into the account in the study of animal heat; but it is only the physiologists who can deal with them in the light of the whole subject. When we have learned to combine the chemical and the physiological view, we may proceed to the tormation of positive doctrine, without having to deal with preliminary obstacles; as, in regard to such questions as the general agreement between the chemical composition of living bodies, and that of the whole of their aliments; a case which constitutes one of the principal aspects of the vital state.
It is evident, at the outset, that every living body, whatever its origin, must be, in the long run, composed of the different chemical elements concerned in the substances, solid, liquid, and gaseous, by which it is habitually nourished; since, on the one hand, the vital motion subjects its parts to a continual renovation, and, on the other, we cannot without absurdity sujjpose it capable of spontaneously producing any real element. This consideration is so tar irom involving any difficulty, that it might lead us to divine the general nature of the principal elements of living bodies; for animals feed in the first place on vegetables, or on other animals which have eaten vegetables; and in the second place, on air and water, which are the basis of the nutrition of plants: and thus, the organic world evidently admits of those chemical elements only which are furnished by the decomposition of air and water. When these two fluids have been duly analysed, physiologists can, in a manner, forsee that animal and vegetable substances must be composed of oxygen, hydrogen, azote, and carbon, as chemistry taught them. It is true, such a prevision must be very imperfect, as it indicates nothing of the difference between animal and vegetable substances, nor why the latter usually contain so much carbon and so little azote. But this hrst glimpse, though it suggests some of the difficulty of the problem, yet indicates the possibility of establishing such a general harmony.
But, when we proceed with the comparison, we encounter important objections, which are at present insoluble. The chief difficulty is that azote appears to be as abundant in the tissues of herbivorous as of carnivorous animals, though the solid aliments of the former contain scarcely any azote. The opinions of chemists, as of J>erzelius and Kaspail, as to the nature of azote, do not solve the difficulty, as they DIVISIONS OF ORGANIC CHEMISTRY. 381 cast no light upon its origin. This is one of a mnltitnclp of cases in which we cannot at all explain the chemical composition of anatomical elements bv that of the exterior substances from which they are iniqnestionably derived. Another striking case is that of the constant presence of carbonate, and, yet more, phosphate of lime in the bonv tissue, though the nature of the aggregate of aliments appears to afford no room for the formation of those salts. This system of investigations, considered in its whole range, constitutes one of the most important general questions that can arise from the chemical study of life; and, if it is at present hardly initiated, the backwardness is owing, not only to its eminent difficulty, but to the biologists having abandoned to the chemists a task which. UTider a wise organization of labour, would have belonged to themselves alone.
In order to effect a rational division of Partition of organic chemistry, and to assign its ]>ortions Oi-o-anic to chemistry on the one hand and physiology Chemistry. on the other, we must talce our stand on the separation between the state of life and that of death; or. what comes to nearly the same thing, between the stability and instability of the proposed combinations, submitted to the influence of common agents. Among the compounds indiscriminately called organic, some owe their existence only to vital motion; they exhibit perpetual variations, and usually constitute mere mixtures: and these cannot belong to chemistry, but must enter into the domain of biologv, — statical or dynamical, according as we study their fixed condition, or the vital succession of their regular changes. Such, for instance, are l)lood, lymph, fat. etc. The others, which form the more immediate principles of these, are substances essentially dead, admitting of a remarkable permanence, and presenting all the characters of true combinations, independent of life: their natural pla.ce i" evidently, in the general system of chemical science, among the substances of inorganic origin, from which they differ in no important respect. Of these, the organic acids, alcohol, albumen, etc., are examples. These are the substances which truly belong to organic chemistry; and no reason exists for their separation from analogous inorganic substances, eveu if no injury was done by sucb an arbitrary division; and there is more reason for giving the title of organic to them than to the theory of oxygen, hydrogen, carbon, and azote, or to the study of many other substances, acid, alkaline, saline, etc., without which chemical anatomy and physiology would be unintelligible. As for chemical phenomena truly common to all compounds of this class, in consequence of the necessary identity of their chief elements, it is certainly important to assign to them their precise relations. The most important of these phenomena relate, at present, to the interesting and very imperfect theory of the diiferent kinds of fermentation. But the consideration of these properties does not constitute a different order from that which results from the same ground in the case of many other comj)ounds, purely inorganic. The property of fermentation, however important, has not a higher scientific value than that of burning, and has no more right to an exclusive classification. It is admitted that too much was attributed to combustion formerly, in regard to inorganic substances; and we may be attributing too much now to fermentation, or any other common property, among so-called organic bodies. We cannot yet assign their proper place to these compounds in the rational system of chemical science; but we are able to affirm that, in that system, they must be more or less sej)arated from each otlier, and interposed among substances called inorganic. Nothing more than this is needed to settle the question of the maintenance or the suppression of organic chemistry as a distinct body of doctrine. In applying the principle which I have proposed, to ascertain to which science any question belongs, it is enough to inquire whether chemical knowledge will serve the purposes of the research, or whether any biological considerations enter into it. The i^roposing such an alternative is, in fact, making the classification.
It is not our business to treat of any special application of this principle; but it is desirable to point out that in this partition of organic chemistry, its two portions are very unequally divided — the study of vegetable substances contributing most to chemistry, and that of animal substances to biology. At the first glance, we might suppose APPLICATION OF DUALISM TO ORGANIC COMPOUNDS. 383 the difference to be the other way; for the iraportance of chemical considerations is really much greater with regard to living vegetables than animals, whose chemical functions are, except among the lowest orders of the zoological hierarchy, subordinated to a superior order of new vital actions. Yet, in virtue of the higher degree of vital elaboration that matter undergoes in the animal than in the vegetable organism, the chemical part of animal physiology j)resents a much greater extent and complexity than the vegetable, in which, for instance, the whole series of the phenomena of digestion is absent, and in which assimilation and secretion are much simplitiecl. But, on account of the superior elaboration, and of the greater number of elements, animal substances are much less stable than vegetable: they rarely remain separate from the organism; and, at the same time, the new immediate principles proj)er to them are so few that their very existence has been questioned. Vegetation is evidently the chief source of true organic compounds, which are derived thence by the animal organism, and modified by it, either thi'ough their mutual combinations or new external influences. Thus, the true domain of chemical science must necessarily be more extended by the study of vegetable than by that of animal substances.
Enovigh has been said about the necessity of subjecting organic compounds to the law of dualism; but there is a particular aspect, under which the importance of this conception in improving chemical theories is worth a brief notice.
In considering substances as ternary or Application of Cjuaternary, their multiplicity is accounted dualism to for only bv the difference in the proportions organic of their constituent elements,— their com- compounds, ponent principles being identical. Very great differences are sometimes explained by inequalities of proportion so small as to shock the spirit of chemical analysis: and in other cases, the proportions being the same, the differences remain unaccounted for; — as, for instance, in the cases of sugar and gum, in which we find the same elements, combined in the same ^proportions. If we extend dualism to organic compounds, this class of anomalies disapj^ears;