pound VO3. Rammelsberg's analysis gave 17.41 per cent. of VO3: a value corresponding to 20.31 per cent. of VO3. In this manner the total results of the analysis are brought up to 99.69; and the isomorphism of Vanadinite with Pyromorphite satisfactorily explained. Before this view can be received, however, it will be for the chemist to determine if there be any real grounds for the assumption of the existence of this higher oxygen compound. So far as present researches go, the tendency of vanadic acid, VO3, would appear to be altogether towards reduction. The question, however, here, is not the conversion of VO3 into VO3, but the reverse: a process which we might readily conceive to take place, were the existence of the latter compound allowed to be probable.

E. J. C.

THE BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. CHELTENHAM, 6th August, 1856.

After the requisite preliminary business, conducted by the General Committee of the Association, and including the reading of the Report of the Council, and of that of the Kew Committee, the body of members assembled to witness the resignation of the Chair by the Duke of Argyle, to his successor, Professor Daubeny, and to hear the President's Address. On this occasion the occupation of the Chair of the British Association by one not only distinguished as a Chemist, but by one who is no less eminent as a Botanist, gave a new character to the Presidential Address. After some preliminary remarks of a personal nature, Dr. Daubeny proceeded with his address, from which we have only room for a brief selection of passages of special interest. Referring to the British Association as alike valuable as an efficient instrument for the furtherance of scientific objects, and as a model after which other associated scientific bodies have been organized, the President thus proceeded:

It is rather remarkable that the first idea of an Association of such a kind should have suggested itself only a year after death had deprived us of our three most distinguished philosophers :-for who had we then left to compare with Davy for the brilliancy and importance of his discoveries; with Young for the singular union of almost universal acquirements with admirable powers of invention; aud with Wollaston for an acuteness of mental vision, which gave him the same advantage in the pursuits of science which the naturalist, armed with a microscope has over the unassisted observer? Just as in the animal economy the vis medicatrix naturæ sometimes makes an extraordinary effort to repair the damage inflicted by injury or disease, so it would seem as if Science, conscious of the loss she had sustained in the almost simultaneous extinction of her three brightest luminaries, endeavoured to make good the deficiency by concentrating into one focus those that yet remained, to light her onwards on her path. At any rate, the progress which the Natural Sciences have made since that period, although doubtless attributable to several concurrent causes, is a fact which must not be overlooked in estimating the services rendered by this Association to the cause of human advancement; nor can I in any better manner point out its value than by bringing before your notice a few of the additions to our knowledge which have been made since I last addressed you.

Beginning then with Chemistry, as the subject with which I am most familiar, let me remind you, that at a period not much more remote than the one alluded to, all of it that could be quoted as really worthy the name of a science was comprehended within the limits of the mineral kingdom. Here at least the outline had been traced out with sufficient precision-the general laws established on a firm basis-the nomenclature framed with logical exactness-the facts consistent with each other, and presented in a scientific and luminous form. Thus a philosopher, like Sir Humphrey Davy, who had contributed in so eminent a degree to bring the science into this satisfactory condition, might, at the close of his career, have despaired of adding anything worthy of his name to the domain of chemistry, and have sighed for other worlds to subdue. But there was a world almost as little known to the chemists of that period as was the Western Hemisphere to the Macedonian Conqueror,— -a World comprising an infinite variety of important products, called into existence by the mysterious operation of the vital principle, and therefore placed, as was imagined, almost beyond the reach of experimental research. This is the new World of Chemistry, which the Continental philosophers in the first instance, and subsequently those of our own country, have during the last twenty years been busy in exploring, and by so doing have not only bridged over the Gulf which had before separated by an impassable barrier the kingdoms of inorganic and of organic nature, but also have added provinces as extensive and as fertile as those we were in possession of before, to the partrimony of Science,

It is indeed singular, that whilst the supposed elements of mineral bodies are very numerous, the combinations between them should be comparatively few; whereas amongst those of vegetable and animal origin, where the ultimate elements are so limited in point of number, the combinations which they form appear almost infinite. Carbon and hydrogen, for instance, constitute, as it were, the keystone of every organic fabric; whilst oxygen, nitrogen, and less frequently sulphur and phosphorus, serve almost alone to build up their superstructure. And yet what an infinity of products is brought about by ringing the changes upon this scanty alphabet! Even one series of bodies alone, that known by the name of the Fatty Acids, comprises several hundred well-ascertained combinations, founded however upon a single class of hydro-carbons or compound radicals, in which the carbon and hydrogen stand to each other in equal atomic proportions, and are in each case acidified by the same number of equivalents of oxygen. These acids are all monobasic, or combine with only one proportion of base; but add to any one of them two equivalents of carbonic acid, and you obtain a member of a second series, which is bibasic, or is capable of forming two classes of salts. The above therefore constitute a double series, as it were, of organic acids, the members of which are mutually related in the manner pointed out, and differ from each other in their mode of combining according to the relation between their respective elements. But already, by the labours of Hofmann and of other chemists, two other double series of acids, the one monobasic, the other bibasic, mutually related exactly in the same manner as those above, have been brought to light; each series no doubt characterized by an equally numerous appendage of alcohole, of æthers, and of aldehydes, to say nothing of the secondary compounds resulting from the union of each of these bodies with others.

Hence the more insight we obtain into the chemistry of organic substances the more we become bewildered with their complexity, and in investigating these phe

nomena, find ourselves in the condition of the explorer of a new continent, who, although he might see the same sun over his head, the same ocean rolling at his feet, the same geological structure in the rocks that were piled around him, and was thus assured that he still continued a denizen of his own planet, and subject to those physical laws to which he had been before amenable, yet at every step he took was met by some novel object, and startled with some strange and portentous production of Nature's fecundity. Even so the chemist of the present day, whilst he recognizes in the world of organic life the same general laws which prevail throughout the mineral kingdom, is nevertheless astonished and perplexed by the multiplicity of new bodies that present themselves, the wondrous changes in them resulting from slight differences in molecular arrangement, and the simple nature of the machinery by which such complicated effects are brought about. And as the New World might never have been discovered, or, at all events, would not have been brought under our subjection, without those improvements in naval architecture which had taken place prior to the age of Columbus, so the secrets of organic chemistry would have long remained unelicited, but for the facilities in the methods of analysis which were introduced by Liebig. Before his time the determination of the component elements of an organic substance was a task of so much skill as well as labour, that only the most accomplished analysts-such men, for instance, as my lamented friend Dr. Prout in this country, or as the great Berzelius in Sweden-could be depended upon for such a work; and hence the data upon which we could rely for deducing any general conclusions went on accumulating with extreme slowness. But the new methods of analysis invented by Liebig have so simplified and so faciliated the processes, that a student, after a few months' practical instruction in a laboratory, car, in many instances, arrive at results sufficiently precise to be made the basis of calculation, and thus to enable the master mind, which is capable of availing itself of the facts before it, to breathe life into these dry numerical details,-just as the sculptor, by a few finishing stokes, brings out the expression of the statue, which has been prepared for him by the laborious chiselling of a number of subordinate workmen. And as the established laws and institutions of the Old World have been modified-may I not say in some instances rectified?-by the insensible influence of those of the New, so have the principles that had been deduced from the phenomena of the mineral kingdom undergone in many instances a correction from the new discoveries made in the chemistry of the animal and vegetable creation. It was a great step indeed in the progress of the science, when Lavoisier set the example of an appeal to the balance in all our experimental researches, and the Atomic Theory of Dalton may be regarded as the necessary, although somewhat tardy, result of the greater numerical pre cision thus introduced. But no less important was the advance achieved, when structure and polarity were recognized as influencing the condition of matter; and when the nature of a body was felt to be determined, not only by the condition of its component elements, but also by their mutual arrangement and collocation-a principle which, first illustrated amongst the products of organic life, has since been found to extend alike to all chemical substances whatever.

Formerly it had been the rule to set down the bodies which form the constituents of the substances we analyzed, and which had never yet under our hands undergone decomposition, as elementary; but the discovery of cyanogen in the first instance, and the recognition of several other compound radicals in organic chemistry more lately, naturally suggest the idea that many of the so-called elements of

inorganic matter may likewise be compounds, differing from the organic radicals above mentioned merely in their constituents being bound together by a closer affinity. And this conjecture is confirmed by the curious numerical relations subsisting between the atomic weights of several of these supposed elements; as, for example, between chlorine, bromine and iodine : an extension of the grand generalization of Dalton, which, although it was unforeseen by the Founder of the system, and therefore, like Gay-Lussac's Theory of Volume, might very possibly have been repudiated by him, had it been proposed for his acceptance, will be regarded by others as establishing, in a manner more conclusive than before, the soundness of his antecedent deductions. What, indeed, can be a greater triumph for the theorist, than to find that a law of nature which he has had the glory of establishing by a long and painful process of induction, not only accommodates itself to all the new facts which the progress of discovery has since brought to light, but is itself the consequence of a still more general and comprehensive principle, which philosophers, even at this distance of time, are still engaged in unfolding?

But passing over speculations which have not as yet received the general assent of chemists, let me advert to others of an older date, possessing, as I conceive, the strongest internal evidence in their favour, which the case admits, from the har. mony they tend to introduce into the chaos of facts which the late discoveries in organic chemistry have brought to light. Amongst these, one of the most generally received, and at the same time one of the most universal application, is that which represents the several combinations resulting from organic forces, as being put together according to a particular model or type, which impresses upon the aggregate formed certain common properties, and also causes it to undergo change most readily, through the substitution of some other element in the place of one of those which already enters into its constitution. And this principle, having been established with regard to one class of bodies, has since been extended to the rest; for it now begins to be maintained, that in every case of chemical decomposition a new element is introduced in the place of one of those which constituted a part of the original compound, so that the addition of a fresh ingredient is necessarily accompanied by the elimination of an old one. The same doctrine, too, has even been extended to the case of combination with a body regarded as elementary, for here also the particles are considered as being in a state of binary combination one with the other, owing perhaps to their existing in opposite electrical conditions, and therefore possessing for each other a certain degree of chemical affinity. Thus, when we unite hydrogen with oxygen, we substitute an atom of the latter for one of the former, previously combined with the same element.

To the microscope we owe all that is as yet known with respect to the reproductive process in cryptogamous plants, which are now shown to possess a structure analogous to that of flowering ones in respect to their organs of reproduction; not, indeed, as Hedwig supposed, that parts corresponding to stamens and pistils in appearance and structure can be discovered in them, but that as the primary distinction of sexes seems to run throughout the Vegetable Kingdom, new parts are superadded to a structure common to all as we ascend in the scale of creation, until from the simple cell, which, in consequence of some differences of structure, to our eyes inappreciable, appears to exercise in one case the function of the male, in another of the female, as is found the case in certain of the Confervæ, we arrive

at length at the complicated machinery exhibited in flowering plants, in which the cell containing the fecundating principle is first matured in the stamen, and afterwards transmitted, through an elaborate apparatus, to the cells of the ovule, which is in like manner enveloped in its matrix, and protected by the series of investing membranes which constitutes the seed-vessel. Thus, as Goethe long ago observed, and as modern physiologists have since shown to be the case, the more imperfect a being is, the more its individual parts resemble each other-the progress of development, both in the Animal and Vegetable Kingdoms, always proceeding from the like to the unlike, from the general to the particular. But whilst the researches of Brown and others have shown that there is no abrupt line of division in the Vegetable Kingdom, and that one common structure pervades the whole, the later inquiries of Suminski, Hofmeister, Unger, Griffith, and Henfrey, have pointed out several curious and unlooked-for analogies between plants and animals. I may mention, in the first place, as an instance of this analogy between plants and animals, the existence of moving molecules, or phytosperms, in the antheridia of ferns and other Cryptogams, borne out, as it has been in so remarkable a manner, by the almost simultaneous observations of Bischoff and Meissner on the egg, confirmatory of those formerly announced by Barry and Newport, and by the researches of Suminski, Thuret, and Pringsheim, with respect to the ovule of plants. I may refer you also to a paper read at the last Meeting of the Association, by Dr. Cohn, of Breslau, who, in bringing this subject before the Natural History Section, adduced instances of a distinction of sexes which had come under his observation in the lower Algæ. In like manner a curious correspondence has been traced between the lower tribes of animals and plants, in the circumstance of both being subject to the law of what is called alternate generation. This consists in a sort of cycle of changes from one kind of being to another, which was first detected in some of the lower tribes of animals; a pair of insects, for example, producing a progeny differing from themselves in outward appearance and internal structure, and these reproducing their kind without any renewed sexual union,-the progeny in these cases consisting of females only. At length, after a succession of such generations, the offspring reverts to its primæval type, and pairs of male and female insects, of the original form, are reproduced, which complete the cycle, by giving rise in their turn to a breed presenting the same characters as those which belong to their own progenitors. An ingenious comparison had been instituted by Owen and others between this alternation of generations in the animal, and the alternate production of leaves and blossoms in the plant; but the researches to which I especially allude have rendered this no longer a matter of mere speculation or inference, inasmuch as they have shown the same thing to occur in ferns, in lycopodia, in mosses, nay, even in the confervæ. We are indebted to Prof. Henfrey for a valuable contribution to our Transactions in 1851 on these subjects, given in the form of a Report on the Higher Cryptogamous Plants; from which it at least appears that the proofs of sexuality in the Cryptogamia rank in the same scale, as to completeness, as those regarding flowering plants did before the access of the pollen tubes to the ovule had been demonstrated. Indeed, if the observations of Pringsheim with respect to certain of the Algæ are to be relied upon, the analogy between the productive process in plants and animals is even more clearly made out in these lower tribes than it is in those of higher organization. It also appears that the production in ferns and other Acrogens of what has been called a pro-embryo; the evolution of antheridia and archegonia, or of male and female organs, from the former; and the generation from the archegonia