"Tum pater omnipotens fœcundis imbribus ather GEORG. II. 3254 After a number of ingenious remarks, M. HUMBOLDT CODcludes the tract with offering a conjecture on the formation of saltpetre. He supposes that the fat and clayey earths, attracting the oxygene from the atmosphere, set loose the azotic gas; which, finding oxygene in the contiguous stratum, enters into a new order of combination, and forms the nitric acid. VII. Experiments on the Constitution of the Atmosphere in the Temperate Zone.-These form a very complete set of meteorological observations, made during the space of five months in the winter season at Salzburg. The spot was very favourable, being a garden to the south of the town, in a sheltered valley, encircled on all sides by stupendous mountains. The quantity of oxygene contained in the air varies sensibly at different times. It probably enters into the formation of clouds; it is evolved in the melting of snow; and the atmosphere even shews greater purity when snow falls in large flakes. Rain, dew, and snow, are highly charged with oxygene. On the tops of mountains, the proper region of clouds, the air is generally more impure than in the plains below. To ascertain the fact, M. Buch made three several journies to the summit of Geisberg, at the height of about 4000 feet; and the air collected there was found by his friend M. HUMBOLDT to contain between one and two per cent. less of oxygene than that of Salzburg. After a thaw has commenced, the atmosphere becomes suddenly purer; owing unquestionably to the oxygenous gas disengaged from the interstices of the snow. In spring, and in the early part of summer, the operation of that cause on the Alpine summits probably more than compensates the tendency to deterioration. VIII. The Evolution of Caloric considered as a Geognostic Phanomenon.This essay contains miscellaneous observations on the geological theories. It is universally admitted, that the mineral bodies on our globe were originally in a fluid state: they must, therefore, in the process of passing into the solid form, have disengaged a certain quantity of heat. This heat, the author conceives, would modify the subsequent compositions. IX. Experiments on the Evolution of Light.-M. HUMBOLDT controverts the opinion hitherto received, that plants derive their green colour from the action of light. From repeated observations, he found that plants confined in the dark, with inflammable or mephitic gases, have the same tints as those which grow in the open air; and he concludes that, in every case, 1 case, the lively verdure of the vegetable tribes owes its production to a mixture in certain proportions of hydrogene and azote.-The object of the present inquiry, however, is to discover the causes of the phosporic appearance of putrid substances. For that purpose, experiments were made with bits of an old rotten water-pipe, of common Scotch fir. From these trials, which were numerous and delicate, it would seem to be demonstrated that the presence of oxygenous gas is essential to the phænomenon. When the rotten wood, inclosed with irrespirable air, grew languid or ceased to shine, the introduction of oxygene invariably freshened or renewed the glow. The carbonic, the azotic, and the hydrogenous gases were particularly subjected to examination: but it was necessary to prepare them with the nicest attention, and to free them completely from all extraneous matters, since the smallest admixture of oxygene is sufficient to maintain the lucid emission for a very considerable time. Putrid substances, however, shine under water. How shall we account for that fact? Is the faint combustion supported by air disengaged from the water? Yet in boiled water, nay in fresh distilled water, the same appearance is exhibited. M. HUMBOLDT thinks that, notwithstanding the vehement application of fire, there is still a residuum of air adequate to the production of the effect. This explanation, we confess, appears extremely forced. Should we not at least expect a diminution of the glow corresponding to the scantier portion of entangled air? Besides, it is idle to suppose the air to be loosely mingled in the water; it is certainly retained with a very considerable force.-The general position is opposed also to some able and ingenious experiments of Mr. Thomas Wedgwood, on light and phosphorescent bodies, published in the Philosophical Transactions for the year 1792, of which an extract appeared in Gren's Physical Journal: but M. HUMBOLDT Submits, with deference, whether the gases were not prepared by Mr. Wedgwood merely in the ordinary way; and whether certain circumstances in the manipulation might not af fect their purity in a slight degree.-Rotten wood loses its phosphorescent quality if immersed in boiling water, or even if exposed to air heated to about the 70th degree of the centigrade scale. That quality is likewise irrecoverably extinguished by dipping the substance in oil, or acidified water. In the subsequent part of the essay, the author enumerates several decided instances in which light derives its source from other bodies than the oxygenous gas, contrary to the sentiments of many philosophers and chemists. X. Experiments on the Influence of the Oxygenated Muriatic Acid on the Germination of Plants, and some correlative appearAPP. REV. VOL. XXX. M m ances. ances. During his residence at Berlin in the winter of 17937 the author discovered that oxygenated muriatic acid accelerates, in a remarkable degree, the germination of plants. This notable fact was published in his Flora Fribergensis, and excited much attention in the scientific world. In the years 1794, 5, and 6, his researches were directed to the theory of animalization; and here likewise he found oxygene to constitute the vivifying principle. When a muscular or nervous fibre was quite exhausted by the action of opium, or the hydrogene of alcohol, it would in a few seconds be revived again to the highest pitch of excitability by a few drops of the oxygenated muriatic acid.-With several chemists, particularly in England, these experiments on vegetation have not succeeded; and M. HUMBOLDT was induced to repeat his observations, and to determine the circumstances which are apt to affect the nature of the result. He directs to sow the cress seeds, which are the most convenient for the purpose, not in siliceous earth or wool, but simply in water with the addition of about one-fourth part of the super-oxydated acid. In two or three minutes, the whole surface of the seeds will be covered with innumerable small air bubbles, though more than half an hour would be necessary. for the same appearances to take place in common water. In six hours, the first protruding germ becomes visible, which would require the space of thirty-two heurs in ordinary cases. In fifteen hours, the radical shoots were often three quarters of an inch long. At the botanic garden of Vienna, in 1798, M. M. Jacquin and Schott threw some old torpid seeds into dilute oxygenated muriatic acid. The experiment fully succeeded: The Guilandina Bonduc, the Cytisus Cajan, the Dedonea Angustifolia, the Mimosa Scandens, and several new species of the Ipomea, germinated. Some of those rare plants are now six or eight inches high. Similar experiments have been made at Dresden and Salzburg. - XI. Pocket or Sink Barometer.-Such is the strange title given to a machine which, when carried, must be slung over the shoulder like a musket. The object of this construction is, that it may be taken occasionally to pieces and examined. In fact, the tube, the bason, and the scale, are all separate, and must be put together as often as an observation is made. This seems to be reverting to the primitive state of the mountain barometer, as it was used by Pascal in measuring the height of the Puy de Dome. We need say nothing more. XII. Letter to Garnerin on the Analysis of the Atmospheric Air, which was collected by means of an Air Balloon at the Height of 669 Toises. It was found to contain about one hundredth part of carbonic gas, and 259 thousand parts of oxygenous gas, while while the air of Paris contained 276 parts. Hence the air of the elevated regions was about two per cent. more impure. The last page announces two new works by the same author, which are shortly to appear. They are entitled, On the Subterranean Gases, and the means of preventing their pernicious effects; and-an Essay on Physics and Practical Mining. The zeal and activity of M. HUMBOLDT are highly commendable, and his sanguine temper will prompt to useful enterprises: but he seems to have caught the passion of his countrymen for voluminous publications. Hence that looseness of composition which we remark, that want of method, and those frequent redundancies. In experimental philosophy, it would be hurtful perhaps to adhere strictly to the precept of Horace, nonum - prematur in annum but surely it is the duty of an author to weigh carefully, and to correct and digest his thoughts, before he obtrudes them on the public. It may be doubted even, notwithstanding all the declamation on that subject, whether the accumulation of isolated facts tends really to the advancement of science. He, whose genius seizes the threads of the connecting analogies, generally founds his theory on properties discovered by himself, or on such as are familiarly known. It is the occupation of the envious to rake into neglected volumes, that they may detract from eminent merit. ART. III. Installation des Vaisseaux, &c. i. e. The Equipment of T HE precise signification of Installation des Vaisseaux, which we have translated the Equipment of Ships, will probably be best explained by the following definition which the author has given :-'it constitutes, if we may so speak, the organization of the vessel, in appropriating each part to the nature and bulk of the fixed and moveable objects which are to be placed there, and in adapting it to all the requisites of navigation, attack, and defence *." Under this title, then, the author has comprehended descriptions of the different parts of a ship of war, with an expla nation of their properties, and of the uses to which each part * Qu'elle constitue, pour ainsi dire, l'organisation du bâtiment, en appropriant chaque lieu à la qualité, et au volume des objets fixes et mobiles à y placer, et en le disposant à tout ce que la navigation, l'attaque, et la défense peuvent en exiger.' * M m 2 should Les..e. should be appropriated; likewise instructions for the dispo sition of the stores, and for the manner of stationing a ship's company to answer the several purposes of battle, of navigation, and of individual accommodation. The first part of the work is divided into seven chapters. Chapter 1. treats of the hold; 11. of the orlop-deck; 111. and iv. of the gun-decks; v. of the quarter-deck, forecastle, and upper works; vI. of the tops; and vii. of the exterior, or outside parts of a ship. In these sections, the explanations are clear, and arranged with method. The subject naturally involves an account of customs and regulations observed in well governed ships of war; and the author has shewn the principles on which many of these regulations are founded, and the particular advantages resulting from them. The second part is composed of tables adapted to the establishment of a ship of seventy-four guns; which shew the stations of a ship's company at their quarters in time of battle; and their stations for various purposes of manoeuvering and navigation. They also contain sundry other lists respecting the interior government of a ship, even to the hammock and mess lists. The whole may be considered in the light of a formula, designed for shewing every thing belonging to a ship in its proper place. In the tables, the author seems to have gone more into the minutiae of detail than may be thought necessary for publication: but to the French marine, in its present state, when it derives so little knowlege from practice, such tables may be useful. Many instances may be observed in which they differ from the methods in general use in the British pavy, as might be supposed from the dissimilar formation of ships' companies in the two marines. The minister of the French marine judged it to be of importance to inquire into the merits of this work, and it was referred to a committe of officers for examination. Their opinion has been very honourable to the author, and it does not appear to us that their approbation has been misplaced. In the report, they remark on the inconveniences occasioned by the want of an uniform mode of management; that, every captain being at liberty to adopt his own particular methods, an inferior officer or a seaman finds himself a new man' on every change of commander, and, however well experienced, may have his lessons to learn afresh. They add that the author proposes fixed methods, which, in practice, will prepare and facilitate the establishment, by an universal regulation, of that order which shall be relatively the same in all the ressels of the republic. The |