of the University of Königsberg; and we are fortunately able to do this with accuracy, from a detailed abstract of them communicated in manuscript by Professor Moser himself to Sir David Brewster. According to his views, light produces the same general effect upon all substances, and this effect consists in its modifying their surfaces, so as to make them condense vapours differently. The quantity of vapours thus condensed, depends on the intensity of the light and the duration of its action; and also on the elasticity of the vapour and the duration of its action. The iodide of silver is at first blackened by the action of light; and this effect is produced most rapidly by the blue and violet rays, and more slowly by the other rays in the ratio of their lesser refrangibility. But when the action of light upon the iodide is prolonged, the blackened iodide is brought back to a coloured iodide; and this restoration is produced most rapidly by the red and yellow rays, and less rapidly by the blue and violet, in the ratio of their greater refrangibility. All bodies, according to Professor Moser, emit light even in absolute darkness, and this light differs entirely from that which is emitted by phosphorescent bodies. It is called by Professor Moser the proper light of bodies. It acts upon all substances in the same manner as ordinary light-that is, it modifies their surfaces, so as to enable them to condense vapours differently. The leading experiment from which this doctrine is deduced, consists in placing a polished surface of silver within the twentieth of an inch of a cameo of horn or agate, with white figures upon a dark ground. After remaining at that distance ten minutes, the figures engraved on the cameo have impressed themselves on the silver surface, and may be rendered visible by throwing upon that surface the vapours of mercury, water, oil, &c. If the image in a camera obscura is received upon a surface of silver, glass, wood, leather, &c., the image may, in like manner, be rendered visible. The proper light of bodies, which has a great refrangibility, is the most suitable for commencing the action upon bodies. From these results, Professor Moser has drawn the important conclusion, that there exists latent light, analogous to latent heat; and that a portion of light becomes latent when any liquid evaporates, and is again disengaged when the same vapour is condensed. The condensation of vapours, therefore, acts like light upon the condensing bodies; particular vapours acting like particular coloured rays of the spectrum. The latent light of mercurial vapours is yellow, and their condensation produces all the effects of yellow light. The latent light of the vapours of iodine is blue or violet. The latent light of chlorine, bromine, and their combinations, differs a little in refrangibility from those of iodine. The latent light of the vapour of water is neither green, yellow, orange, nor red. The latent light of the hydro-fluoric vapours, surpasses in refrangibility that of the visible rays. Hence Professor Moser concludes, that the iodide of silver derives its great sensibility to ordinary light, from the circumstance that the latent light of the vapour of iodine is disengaged, and acts on the substance of the metal; and that the iodide of silver has not a greater sensibility to the invisible rays than pure silver.* These general results are deduced from various experiments detailed in three memoirs; only one of which is yet published in Poggendorff's Annalen der Physik. This first memoir is On Vision, and the Action of Light upon all Bodies; the second, On the Latent State of Light; and the third, On Invisible Rays. The published Memoir indicated at the head of this article, contains many interesting experiments connected with the Daguerreotype; but the most important part of it is that in which its author assimilates the phenomena of vision to those of Photography. In developing his particular views on this subject, he founds them on the following experiment made by Sir David Brewster, which he regards as a complete proof of his theory : If, when two candles are placed at the distance of eight or ten feet from the eye, and about a foot from each other, we view the one directly, and the other indirectly; the indirect image will swell, as we have already mentioned, and will be succeeded with a bright ring of yellow light, while the bright light within the ring will have a pale-blue colour. If the candles are viewed through a prism, the red and green light of the indirect image will vanish; and there will be left only a large mass of yellow, terminated with a portion of blue light. In making this experi ment, and looking steadily and directly at one of the prismatic images of the candles, I was surprised to find that the red and green rings began to disappear, leaving only yellow and a small portion of blue; and when the eye was kept immovably fixed on the same point of the image, the yellow light became almost pure white; so that the prismatic image was converted into an elongated image of white light.-(Treatise on Optics, p. 296, 297.) Professor Moser regards this experiment as inexplicable by the ordinary theory of accidental colours; and ascribes the phenomena to a peculiar vital action not yet understood. We have found that many of the phenomena ascribed to latent light, or to heat, are owing to the absorption of matter in the state of vapour or minute particles, passing from the object to the surface of the glass or metal upon which the image of that object is impressed; and by this means we have obtained very fine pictures upon glass, which are positive when seen by reflection, and negative when seen by transmitted light. These pictures are rendered visible by the vapour of water, &c. In the middle of this physiological difficulty, our exhausted limits compel us to stop. But we cannot allow ourselves to conclude this article without some reflections, which the preceding details must have excited in the minds of our readers, as well as in ours. Two great inventions, the produce of two of the greatest and most intellectual nations in the world, have illustrated the age in which we live. With a generous heart and open hand, France has purchased the secret of the Daguerreotype; and while she has liberally rewarded the genius which created it, she has freely offered it as a gift to all nations-a boon to universal science-a donation_to the arts-a source of amusement and instruction to every class of society. All the nations of Europe-save one-and the whole hemisphere of the New World, have welcomed the generous gift. They have received the free use of it for all their subjects; they have improved its processes; they have applied it to the arts; they have sent forth travellers to distant climes to employ it in delineating their beauties and their wonders. In England alone, the land of free-trade-the enemy of monopoly-has the gift of her neighbour been received with contumely and dishonour. It has been treated as contraband-not at the Custom-house, but at the Patent-office. Much as we admire the principle of our Patent laws, as the only reward of mechanical genius under governments without feeling and without wisdom, we would rather see them utterly abrogated, than made, as they have in this case been made, an instrument of injustice. While every nation in the world has a staff of pilgrim philosophers, gathering on foreign shores the fragments of science and practical knowledge for the benefit of their country, England marshals only a coast-guard of patent agents, not to levy duties, but to extinguish lights; not to seize smugglers, but to search philosophers; not to transmit their captures to the national treasury, but to retain them as fees and profits to interested individuals. Nor does the fate of the Calotype redeem the treatment of her sister art. The Royal Society-the philosophical organ of the nation has refused to publish its processes in their Transactions. No Arago-no Gay Lussac, drew to it the notice of the Premier or his Government. No representatives of the People or the Peers unanimously recommended a national reward. No enterprizing artists started for our colonies to portray their scenery, or repaired to our insular rocks and glens to delineate their beauty and their grandeur. The inventor was left to find the reward of his labours in the doubtful privileges of a patent; and thus have these two beautiful and prolific arts been arrested on English ground, and doomed to fourteen years' imprisonment in the labyrinths of Chancery Lane! ART. II.-Speeches of LORD CAMPBELL, at the Bar, and in the W E regard the publication of this volume with interest, not derived merely from the intrinsic merit of some of the speeches which it contains, and the importance of the events with which they are associated; but from the memorials it presents of a career which it is pleasant to contemplate, and wise to hold out as an encouraging example. The professional life of its author is not illustrated by those sparkling qualities which sometimes attain a sudden triumph, and which few can emulate; nor diversified by those happy accidents which occasionally decide the fate of a bold aspirant, when trembling between obscurity and greatness; but consists of an uninterrupted course of strenuous labours, sustained with unflinching courage and unwearied patience, and, by constant and regular progress, achieving high and merited honours. From the political party to which he attached himself in youth, notwithstanding its attainment of power then beyond all expectation, he has derived no other pecuniary benefits than the office of Attorney-General conferred -the painful and ill-paid duties of which he discharged for a longer period than any of his predecessors, and with industry and care which none of his successors can ever surpass; so that of the numerous lawyers who have attained high rank, and founded noble families, he has, as much as any one within our recollection, directly worked for and earned his fortune, by that persevering toil which inferior minds may imitate with proportionate success, and which none can imitate in vain. His course has also the merit and the beauty-too often wanting, or imperfect in the history of eminent lawyers-of entire political consistency. Early in life he chose his party for better and for worse; clove to it with constancy; and now advocates in the House of Lords those principles which he embraced when their success seemed a distant hope, and which, notwithstanding the present exclusion from office of those by whom they have been supported, are, and will continue triumphant. And without imputing dishonourable motives to those successful lawyers whose career has wanted, or seemed to want, this grace-believing that the changes imputed to them have rarely been attended by feelings consciously base-we may be permitted to regard it as a ground of congratulation, when a long public career wears all the outward symbols of the integrity which has influenced its secret springs of action; when the objects of youthful and enthusiastic affection are the same with those of matured attachment; and when the whole course of active and contemplative existence is in keeping and harmony. We should have liked this volume better if it had comprised a greater variety of speeches at the Bar, illustrating the stages of its author's progress-many of which, if we recollect rightly, were inspired by occasions of great forensic interest, and which, eminently successful with courts and juries, would have been of much value to the student of common law; and for these we could have spared the ponderous argument on the question of Parliamentary Privilege, though it is a remarkable instance of industry in searching for all possible materials, and of perfect mastery obtained over them. But perhaps the means of reviving those efforts, which were attended with the most signal success, did not remain; or the difficulty of rendering them intelligible, without a full detail of all the surrounding incidents, may have presented insuperable obstacles in the way of such a selection. This last difficulty considerably detracts from the effect of the first speech of this volume-the defence of the action of Nor'ton v. Lord Melbourne'-which, heard in connexion with the evidence which it dissects and exposes, produced entire conviction of the utter baselessness of the case which the plaintiff had been induced-we believe against his own better judgment-to bring into court, and well entitled the advocate to the cheers with which he was greeted on entering the House of Commons, after the verdict was given. Other objections have been urged to the publication of this speech, which we do not think equally valid. If, indeed, it were possible to obliterate all remembrance of an attempt-made not by, but through the ostensible plaintiff to crush the First Minister of the Crown, by sacrificing the reputation and the peace of a beautiful and richly-gifted woman-we grant that such oblivion of the endeavour would be wisely purchased by the suppression of the effort which destroyed it. But this is surely impossible-not only because the position held by the defendant in the councils of his sovereign, from which an adverse verdict must have driven him, renders the attack part of the history of the times, but because the celebrity of the lady, exposed to double envy by the dangerous gifts of genius and beauty, imparts to her sorrows that undying interest which always attends suffering when associated with high endowments. If the splendour of hereditary association, and her own just claims to fame, deny to her the refuges of mediocrity, and preserve the memory of her trials, it is surely better that the record of the exposure of the attempt in which her character was in |