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impregnated with nitrous gas. A small quantity of the former prevents the decomposition of nitrous gas and water by the green oxyd of iron.

The fifth division of the first research contains experiments and observations on the production of nitrous oxyd, from nitrous gas and nitric acid, in different modes. These experiments relate to a variety of close chemical details, which we cannot follow with interest or advantage. They are of importance only to the minute and scientific chemist, who must read the whole without change or mutilation.

The second research contains inquiries into the combinations of nitrous gas, and its decomposition by inflammable substances. It combines, as we have said, with water; and Mr. Davy tells us he has drank three pints of it in the course of the day. It appeared to act as a diuretic, and I imagined that it expedited digestion.' In point of taste, which is said to be sweetish and acidulous, he preferred it to common water. This oxyd has less affinity for water than even the weaker acids, sulphurated hydrogen, and carbonic acid; but it has a stronger attraction than gases not possessed of acid or alkaline qualities. Our author next examines the combination of nitrous oxyd with inflammable bodies, as well as the action of fluid acids, alkaline solutions, and different gases on this oxyd. The union of the nitrous oxyd with alkalis, either in the solid or aëriform state, seems a favourite problem with our author, who has attempted it in a variety of ways. He thinks this oxyd unites intimately with fixed alkalis, and that the compounds are insoluble in alkalis, as well as decomposable by acids and heat. These compounds he styles nitroxes, and affirms that the nitrous oxyd is of an acid nature; but as it does not redden the blue vegetable juices, and has not a distinct acid taste, he considers it for the present as a body sui generis. On the subject of the decomposition of nitrous oxyd by inflammables, we must transcribe the author's general conclusions. The detail would be too

extensive.

From what has been said in the preceding sections, it appears that the inflammable bodies, in general, require for their combustion in nitrous oxide, much higher temperatures than those at which they burn in atmospheric air, or oxygene.

When intensely heated they decompose it, with the production of much heat and light, and become oxygenated.

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During the combustion of solid or fluid bodies, producing flame, in nitrous oxide, nitrous acid is generated, most probably from a new arrangement of principles, analogous to those observed in sect. ii. by the ignition of that part of the gas not in contact with the burning substance. Likewise, when nitrous oxide in excess is decomposed by inflammable gases, nitrous acid, and sometimes a gas analogous to common air, is produced, doubtless from the same

cause.

Pyrophorus is the only body that inflames in nitrous oxide, below the temperature of ignition.

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Phosphorus burns in it with the blue flame, probably forming with its oxygene only phosphoreous acid at the dull red heat, and with the intensely vivid flame, producing phosphoric acid at the white heat.

Hydrogene, charcoal, sulphur, iron, and the compound inflammable bodies, decompose it only at heats equal to, or above, that of ignition probably each a different temperature.

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From the phænomena in sect. v. it appears, that at the temperature of intense ignition, phosphorus has a stronger affinity for the oxygene of nitrous oxide than hydrogene; and reasoning from the different degrees of combustibility of the inflammable bodies, in mixtures of nitrous oxide and nitrogene, and from other phænomena, we may conclude, with probability, that at about the white heat, the affinity of the combustible bodies for oxygene takes place in the following order. Phosphorus, hydrogene, charcoal, iron, sulphur,

&c.

This order of attraction is very different from that obtaining at the red heat; in which temperature charcoal and iron have a much stronger affinity for oxygene than either phosphorus or hydrogene.

The smallest quantity of oxygene, given in the different analyses of nitrous oxide just detailed, is thirty-five hundred parts; the greatest proportion is thirty-nine.

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Taking the mean estimations from the most accurate experi ments, we may conclude that 100 grains of the known ponderable matter of nitrous oxide, consist of about 36,7 oxygene, and 63,3 nitrogene; or taking away decimals, of 37 oxygene to 63 nitrogene; which is identical with the estimation given in Research Ï.' P. 322.

During these decompositions there is a momentary expansion of the ingredients, connected with increased temperature, and a vivid light. On this subject the author does not engage, and we need not attempt any discussion. We shall conclude our account of this part of the work with a comparison of the various combinations of oxygen and nitrogen.

That the oxygene and nitrogene of atmospheric air exist in chemical union, appears almost demonstrable from the following

evidences.

1st. The equable diffusion of oxygene and nitrogene through every part of the atmosphere, which can hardly be supposed to depend on any other cause than an affinity between these principles.

zdly. The difference between the specific gravity of atmospheric air, and a mixture of 27 parts oxygene and 73 nitrogene, as found by calculation; a difference apparently owing to expansion in consequence of combination.

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3dly. The conversion of nitrous oxide into nitrous acid, and a gas analogous to common air, by ignition.

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4thly. The solubility of atmospheric air undecompounded in

water.

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Atmospheric air, then, may be considered as the least intimate of the combinations of nitrogene and oxygene."

It is an elastic fluid, permanent at all known temperatures, consisting of 73 nitrogene, and ,27 oxygene. It is decomposable at certain temperatures, by most of the bodies possessing affinity for oxygene. It is soluble in about thirty times its bulk of water, and, as far as we are acquainted with its affinities, incapable of combining with most of the simple and compound substances. 100 cubic inches of it weigh about 31 grains at 55° temperature, and 30 atmospheric pressure.

Nitrous oxide is a gas unalterable in its constitution, at tempe ratures below ignition. It is composed of oxygene and nitrogene, existing perhaps in the most intimate union which those substances are capable of assuming *. Its properties approach to those of acids. It is decomposable by the combustible bodies at very high temperatures, is soluble in double its volume of water, and in half its bulk of most of the inflammable fluids. It is combinable with the alkalies, and capable of forming with them peculiar salts. 100 grains of it are composed of about 63 nitrogene, and 37 oxygene. 100 cubic inches of it weigh 50 grains, at 550 temperature, and 30 atmospheric

pressure.

Nitrous gas is composed of about ,56 oxygene, and ,44 nitrogene, in intimate union. It is soluble in twelve times its bulk of water, and is combinable with the acids, and certain metallic solutions; it is possessed of no acid properties, and is decomposable by most of the bodies that attract oxygene strongly, at high temperatures. 100 cubic inches of it weigh about 34 grains, at the mean temperature and pressure.

Nitric acid is a substance permanently aëriform at common temperatures, composed of about 1 nitrogene, to 2,3 oxygene. It is soluble to a great extent in water, and combinable with the alkalies, and nitrous gas. It is decomposable by most of the combustible bodies, at certain temperatures. 100 cubic inches of it weigh, at the mean temperature and pressure, nearly 76 grains.' P. 326.

The third research relates to the respiration of nitrous oxyd and other gases. It was found to be destructive, after some time, to warm-blooded animals, previously exciting their powers to a great extent; and more so to small than to large, to young than to old animals; but if the experiment be checked before the animal is completely exhausted, he may recover by exposure to atmospheric air. Animals, however, lived twice as long in nitrous oxyd as in hydrogen or water. The bodies of animals, killed by it, exhibited peculiar appearances. The irritability was greatly lessened, and the blood was of a purple red; thus combining the effects of respired with those of inflammable air. The lungs were covered with purple spots. Amphibious animals, fishes and insects, soon die in atmospheres of nitrous oxyd, or in water strongly impregnated with it. Animals are destroyed by the respiration of mixtures of nitrous

For it is unalterable by those bodies which are capable of attracting oxygene from nitrous gas and nitrous acid, at common temperatures.

oxyd and hydrogen, nearly as in pure nitrous oxyd; nor can they live long in nitrous oxyd, mingled with very minute quan tities of oxygen or common air.

Various circumstances respecting the effects of the respiration of nitrous oxyd follow, which we cannot notice, and which indeed furnish nothing very decisive. Different portions of the gas were absorbed by venous blood, and some portions of nitrogen and carbonic acid were at the same time separated. It was not, however, easy to determine how much was owing to the usual effects of respiration when these changes were observed during the action of this function; for the oxyd was absorbed while the other gases were discharged; and we must wait for farther inquiries on this subject,

Mr. Davy next made many experiments to respire different gases. We have already heard enough of the exhilarating effects of the nitrous oxyd. Hydrocarbonate appeared to be merely sedative. Carbonic acid air, when pure, stimulates the glottis, and prevents its admission into the lungs when diluted, it pro duces giddiness. Simple oxygen produced oppression on the chest, and no other sensation or effect. Nitrous air produced a stricture also on the glottis; and, when atmospheric air was afterwards breathed, nitrous acid was formed in the fauces, so as to excite active inflammation. We shall copy one of our au thor's descriptions of the effects of nitrous oxyd.

The moment after, I began to respire 20 quarts of unmingled nitrous oxide. A thrilling extending from the chest to the extremities was almost immediately produced. I felt a sense of tangible extension highly pleasurable in every limb; my visible impressions were dazzling and apparently magnified, I heard distinctly every sound in the room, and was perfectly aware of my situation. By degrees, as the pleasurable sensations increased, I lost all connexion with external things; trains of vivid visible images rapidly passed through my mind, and were connected with words in such a manner, as to produce perceptions perfectly novel. I existed in a world of newly connected and newly modified ideas. I theorised; I imagined that I made discoveries. When I was awakened from this semi-delirious trance by Dr. Kinglake, who took the bag from my mouth, indignation and pride were the first feelings produced by the sight of the persons about me. My emotions were enthusiastic and sublime; and for a minute I walked round the room perfectly regardless of what was said to me. As I recovered my former state of mind, I felt an inclination to communicate the discoveries I had made during the experiment. I endeavoured to recall the ideas, they were feeble and indistinct; one collection of terms, however, presented itself: and with the most intense belief and prophetic manner, I exclaimed to Dr. Kinglake, "Nothing exists but thoughts!--the universe is composed of impressions, ideas, pleasures and pains!" P. 487.

The feelings of different persons on breathing this air are aftcrwards noticed; and, in some irritable females, it seemed to

produce hysteric affections. We do not enlarge on this subject, because we wish the experiments to be more generally tried.To vegetables this air was soon fatal.

ART. IX.-Travels in the Ottoman Empire, Egypt, and Persia, undertaken by Order of the Government of France, during the first six Years of the Republic, by G. A. Olivier, &c. Illustrated by Engravings; consisting of Human Figures, Animals, Plants, Maps, Plans, &c. To which is prefixed a Map of Greece, of the Archipelago, and of a Part of Asia Minor. Translated from the French. 2 Vols. 8vo. with 4to Atlas, 11. 6s. 6d. Boards. Longman and Rees. 1801.

THESE travels commenced in the infancy of the French republic, when the Cincinnati, drawn from the plough, thought that something, they knew not what, should be done to secure old friends or to obtain new ones. M. Olivier and his companions were consequently sent to Constantinople, and forgotten. The want of a consistent plan, perhaps the want of sufficient funds, but, above all, the want of judgement-whence arose numerous other wants, undigested designs adopted and forsaken, eagerly begun and childishly abandoned-disgraced the early youth of these unfledged statesmen. M. Olivier, however, did as well as he was able, without assistance or credit from his own country, and in opposition to the prejudices of those among whom he resided, both against his cause and his nation. He has published his Travels, though we can scarcely see for what purpose. Turkey has been often described; and he hardly adds a feature to the portrait. The manners of the Turks have been the subject of numerous narratives; and he adjoins few facts of importance to the collection. Their customs and even their prejudices are the same as when they first appeared in Europe. They still prefer their own ignorance to the knowledge they might derive from nations whom they despise; and indulge the incurious idleness which their religion applauds, and from which the monarchy derives numerous advantages. Our author's predecessors, Savary, baron Tott, Volney, lady Mary Wortley Montague, Dallaway, and Sonnini, have described them in succession, without giving a more favourable likeness. If we be indebted to the present writer for any new instructions respecting Turkey, they relate to its political state, the advantages of its situation, and some circumstances of the domestic habits of the Turks: yet, on each subject, it is difficult to select what is new, or related in a new style. M. Olivier ranks high as a natural historian; but his publications are con

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