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deserve the name of a nation. All the Nogais still bear more or less in their countenance the marks of their Mongul descent. Some look exactly like the offspring of the first mixture of Mongul, or Kalmuck, with Tartar or Russian blood. In consequence of their unsettled mode of life, the Nogais have continued to be addicted to plunder, although they have greatly suffered from severe but well deserved chastisements. It was formerly the custom to lop a hand and a foot from the party caught in the fact. Their tribesmen, as the late Dr. Lerch asserted from his own observation, used to staunch the blood with hot milk or fat, and carry off their mutilated fellows.

A peculiar race, who have been obliged to retire into the high mountains, are the Ossetes or the Irones. Of these the Dugenous are the most powerful. They have lived a long time separated from the others, partly subject to the Badiletters, a race of horsemen resident in the mountains, and partly independent.

Near to their glaciers, where the Chamois feeds, there is said to be found a large bird of the Pheasant genus, very beautiful in its plumage, and accustomed to warn the Chamois when he sees men on the solitary mountains.

Another tribe, totally different in language, stature, and physiognomy, from the rest of the inhabitants of Caucasus, are the Galgai, or the Gamur; or Inhabitants of the Mountains, as they entitle themselves. Their pronunciation is performed as if they had stones in their mouth. They are said to be an upright and brave people, who have been able to maintain their independence; being subject only to their own elders, who at the same time are their priests. They are almost the only Cauca. sians who have retained the shield among their weapons.

The Suani are described as another mountain tribe ; and a few words are said respecting some others.

The volume concludes with a journey from Georgiofske ta Tcherkask and Taganrog, and from Taganrog to Tauria. Of the illustrative and decorative engravings, we shall speak in our account of the second, yet unpublished, volume. - In the mean time, we may remark of the present, that by far the greater part has no universal interest. We have not met with any work more susceptible of judicious abridgment; and among the students of German literature, it would be rendering a public service if some one would undertake this task, both with the present and the former travels of this intelligent and authentic observer ---Of both, there are French editions.

Bed...s.

Авт. .

ART. II. Versuche über die Chemische Zerlegung des Luftkreises, &c.i.e.

Experiments on the Chemical Decomposition of the Atmosphere, and on some other objects in Natural Philosophy. By Alex. von HUMBOLDT. With two Copper-plates. 8vo. Pp. 260.

Brunswick. 1799. THIS

His small volume contains a number of ingenious and well

conducted experiments, which display all the precision, clegance, and resources of modern chemistry. Many of the results are curious.; some of them are striking and important. The researches were made in various parts of Germany, on the borders of Italy, and especially in France, where the Parisian schools afforded peculiar advantages : but every where the youthful author seems to carry along with him the same ardent passion for science, and the same assiduous and indefatigable perseverance; which must in the end achieve valuable discoveries. Disappointed in the plan of accompanying the Gallic expedition to Egypt, he has directed his adventurous curiosity to the western world, and is at present, we understand, employed in exploring the unfrequented regions of Peru.

Chemical theory has in its progress attained the period at which a pause naturally ensues. It connects together an ex. tensive and splendid range of facts, with an ease and apparent consistency that gratify the imagination ;-and so did the vortices of Des Caries, with this additional advantage, of transferring for the first time the laws of force observed on our globe to regulate the motions in the celestial spaces. It was not enough, however, to explain the general features; it was indispensable that the effects deduced should be exactly commensurate with the phænomena. The Cartesian hypothesis melted away under the touch of geometry.-- Whether the received opinions in chemistry be destined to undergo a similar fate, time will decide. The simplicity of the superstructure, however engaging, is certainly premature; the basis requires to be extended ; and many adaptations are wanted to maintain coherence among the different parts. Recent experimenters, in detailing their operations, affect a degree of precision which is warranted neither by the state of the science, nor by the nature of the instruments employed. Yet how discordant are the results of different analyses! To impeach the skill or attention of the experimenter, would be uncandid: but are the principles themselves of chemical combination rightly understood or fully established ? When the term affinity was rejected 23 occult, as metaphorical, and as savouring of alchemy, vas "any real adrantage gained by substituting the expression elective attraction? Or is not this phrase composed of incongruous elements? The epithet elective transfers the qualities of sentient beings to unorganized and dead matter; while the word attraction implies the application of that system of forces, which, in its simpler form, constitutes the most perfect of all the physical sciences; and which, modified by the law of distance only, arranges on the one hand the primordial molecules, and on the other extends its empire into the boundless regions of space. The power which unites chemical substances is not absolute and unvaried. In proportion as we approach the limit of saturation of a compound, the mutual adhesion of its ingredients becomes more and more languid. Hence, though the initial attraction for instance, of a substance A to B be much greater than that of C to B, there is always some intermediate point in the process of the absorption of B, when the force of A, now enfeebled, is counterpoised by the undiminished action of C. It is impossible, therefore, by the help of any re-agents, strictly to resolve a mass into its true elements; the products must always deviate more or less from the just proportions, according to the comparative attractions which are brought into operation. If we add the cohesion of the integrant particles of solids, and consider the various modifications resulting from heat, pressure, and other circumstances, we need not be surprized to view the contrast and discrepancy of different analyses. To refine chemistry in its most essential principles, it would be necessary not only to determine the initial attractions of the common agents, but to investigate the law of the dininution of those forces corresponding to the progress towards saturation. The task is difficult, indeed, and laborious but in the sequel it would perhaps be found that certain analogies, simple in their application, pervade whole classes of objects, and produce all that complication of appearances which at present we despair to unravel.

attraction

It was unfortunate, it was rash and illogical, to assume that all the gases are derived from solid bases. The great Lavoisier was evidently misled by the notion of latent hent; an hypothesis originally founded in paralogism, and which has materially impeded the progress of science :--but is there not a radical distinction between vapours and permanent gases? And even granting that various additions of heat are capable of changing any solid successively into the liquid and the aeriform state, what reason is there for maintaining the converse of the proposition ? The adherents of phlogiston have been accused, and with reason, of creating an imaginary existence:--but are their opponents altogether exempt from similar reproach? What are pxygene, hydrogene, azote, bui étres de science, beings not cogni

zable

zable by the senses, and not denionstrated by their perceived effects. The corresponding gases only are known, and, in all their combinations, these still betray the properties of elastic fluids. Oxyds, for example, possess much less density than the metalsthemselves; --whence proceeds this distending power? Does not the enlargement of volume decidedly evince a repulsion among the particles of the absorbed air, and which is coerced by the superior attraction of the metal? The same reasoning will apply to a multitude of other facts.

If a mutual attraction subsists among all the different species of air, (as every thing seems to indicate,) the experimenters in that department have committed a grievous oversight, in supposing the bulk of a mixed gas to be equal to the sum of the balks of its components. Hence their analyses will often, from that single cause, be affected with considerable errors. The ordinary pneumatic apparatus, too, however convenient in the infancy of science, is but an aukward contrivance, calculated only to measure gross and palpable quantities:--but to detect the more recondite operations of nature, it is of the utmost consequence to mark the minute alterations of volume, and to exhibit to the senses those delicate transitions which take place in the corpuscular phænomena. Instead of measuring the space occupied by gases, it would be incomparably more accurate to estimate the change of their elasticity by its pressure on a slender column of coloured liquid.

Having stated these preliminary remarks, which, we trust, will not be judged altogether misplaced, we shall now proceed to examine the tracts before us in the order of their occurrence.

1. Experiments on Nitrous Gas, and its combinations with Oxygene.-Convinced that eudiometrical experiments, as uslially performed, are liable to great uncertainty, and require skilful manipulation, we have always regarded the consequences drawn from them with peculiar hesitation and mistrust. The theory supposes that all the oxygene, contained in the air subjected to trial, unites with a corresponding portion the nitrous gas to form an acid deposition : but is this acid uniform in its constitution? Does it not assume every possible condition, from the state of red fumes to that of a liquid fixed and limpid? Why presume that the nitrous gas itself is not exposed to a similar variety of composition ? Such reflections leave the subject in perplexity; yet it is further apparent that our suspicions were grounded from M. HUMBOLDT's experiments. These are numerous, and appear to be performed with scrupulous attention : but they are related with such circumstantial detail, and with such frequent repetitions and inci

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dental remarks, as to prove tiresome in the perusal. We shall notice only the more prominent results.

Authors are not agreed how much nitrous gas is absorbed by one part of the oxygenous : some reckon the proportion at 3, or even 5 ; Lavoisier states it at 1.8: but M. HUMBOLDT, from a comparison of different analyses, fixes it at 2.55Nitrous gas is not constantly the same; it is modified by the state of concentration of its radical acid, to such degree as to contain a varying excess of azote from 10 to 68 per cent. The gas most suitable for chemical experiments is that which is procured from copper-wire, dissolved in dilute nitric acid of between 17 and 20 degrees of Baumé's arcometer; it contains ouly 10 or 15 per cent. of surplus azote.-It appears that, when the nitrous and oxygenous gases are mixed in a mercurial apparatus, there is scarcely any sensible precipitation. In ordinary cases, therefore, the contiguous surface of water must perform an important office in assisting the combination. Hence the effeci of the concurrence of those two gases depends, in some measure, on the width of the receivers ; in narrow tubes, the quantity of absorption which takes place is greatly diminished. If distilled water be shaken with nitrous gas, a portion of the water will be decomposed, and will form, by the play of double affivities, the nitrat of ammoniac. The solution of the sulphat of iron almost completely absorbs the nitrous gas, detaching the azote, and at the same time composing nitrat of iron and sulphat of ammoniac. The oxygenated muriatic acid, however, detaches still more azote from the

Yet we do not see on what solid grounds. M. HUMBOLDT considers the azote as only adventitious in the nitrous gas, and not constituting an integral part of that varied substance. The mixture of the nitrous with the oxygenous gas affords not such regular results as that with atmospheric air ; nor does the artificial compound of 27 parts of oxygenous gas, and 73 of the azotic, manifest on trial the same properties as the air which we breathe. These facts betray the lameness of received principles, and excite suspicions with respect to the legitimacy of some capital analyses. Yet M. HUMBOLDT is not discouraged ; and, where the agents are concealed and involved, it is not difficult to imagine a solution of each anomalous appearance. He infers that the quantity of oxygene contained in common air may be ascertained with tolerable accuracy, by dividing the volume absorbed of equak parts of air and nitrous gas from dilute acid, by the number 3:55:—but the proportion may be determined with great nicety, by examining the residuum of the mixture, by the help of the sulphat of iron. Nay, with the application likewise of

the

nitrous gas.

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