them by comprehending differerit sounds under one and the same sound or monosyllable. Thence it is that some reckon 330, others 340, and others 500. The diversity of sounds in different provinces prevents the possibility of certainly fixing them.'

ART. VIII-Researches, Chemical and Philosophical; chiefly concerne

ing Nitrous Oxide, or dephlogisticated Nitrous Air, and its Rea spiration. By Humphry, Davy, Superintendent of the Medical Pneumatic Institution. 8vo. zs. Boards. Johnson.

THE discovery of the dephlogisticated nitrous air was one of the lucky hits' of Dr. Priestley in his random trials on different species of aërial fluids, begun without a plan, and concluded without any satisfactory information. It was consequently left, as a mere gleaning, to the test of more scientific inquirers. The fate of this gaseous substance is peculiarly singular. In the western hemisphere, it was, according to Dr. Mitchell, the septon, the corrupting principle, the source of disease and death: in our more enlightened regions, it animates with peculiar spirit; it pose sesses the exhilarating principle of wine without its intoxicating quality; it enlivens, without the mixture of any narcotic power, without being followed by any sedative influence. We once witnessed the effect of this singularly exhilarating draught; but we never experienced it, for the consequences were too serious; and we were not sure, were the expressions of hilarity genuine, that the patient might not have been condemned to the discipline of coërcion and a strait waistcoat. It has since, we find, in a more dilute state, been employed as a remedy for palsy, for atony, and the whole class of incurable diseases;-with what success, we are yet to learn.

By these remarks, we mean no reflexions on Mr. Davy, whom we have already met in the walks of science; and if we havé reprehended his forward eagerness, he has made the amende honorable by abandoning his crude and unscientific views. We now find him correct and exact in his experiments; in the present instance somewhat inclined to elevate and surprise ;-but he is still young.

• In the arrangement of facts, I have been guided as much as possible by obvious and simple analogies only. Hence I have seldom entered into theoretical discussions, particularly concerning light, heat, and other agents, which are known only by isolated effects.

• Early experience has taught me the folly of hasty generalisation. We are ignorant of the laws of corpuscular motion ; and an immense mass of minute observations concerning the more complicated chemical changes must be collected, probably before we shall be able

n the first researcplains the prand its combinazivision.

ions olempt was as are the acid, and ition of nitrous a

to ascertain even whether we are capable of discovering them. Chemistry in its present state is simply a partial history of phänomena, consisting of many series more or less extensive of accurately cone nected facts.' P. xiii,

In the first research our author analyses the nitrous acid and nitrous gas, and explains the production of the nitrous oxyd. The composition of nitric acid, and its combinations with water and nitrous gas, are the sụbjects of the first division. The first attempt was to reconcile the apparently inconsistent conclu. sions of M. Lavoisier and Mr. Cavendish, respecting the composition of the nitrous acid. The experiments for this purpose are very minute, and accurately executed. The idea of forming a standard acid, with which to compare the others, is yery ingenious, and we shall extract the description of it,

We may then conclude, First, that 100 cubic inches of nitrous acid, such as exists in the aëriform state saturated with oxygene, at temperature 55', and atmospheric pressure 30,1, weigh 75,17 grains.

Secondly, that 100 grains of it are composed of 68,06 nitrous gas, and 31,94 oxygene. Or assuming what will be hereafter proved, that 100 parts of nitrous gas consist of 55,95 oxygene, and 44,05 nitrogene, of 29,9 nitrogene, and 70,1 oxygene ; or taking away de çimals, of 30 of the one to 70 of the other. < « Thirdly, that 100 grains of pale green solution of nitrous acid in water, of specific gravity 1,301, is composed of 50,62 water, and 49,38 açid of the above composition,' P. 19

• Comparing the different synthetical and analytical experiments, we may conclude, with tolerable accuracy, that 92,75 grains of bright yellow, or standard acid of 1,5, are composed of 2,75 grains of pitrous gas, and go grains of nitric acid of 1,504; but 92,75 grains of standard acid contain 85,23 grains of nitrous acid, composed of about 27,23 of oxygene, and 58, nitrous gas : now from 58, take 2,75, and the remainder 55,25, is the quantity of nitrous gas contained in go grains of nitric acid of 1,504; consequently, 100 grains of it are composed of 8,45 water, and 91,55 true acid, containing 61,32 nitrous gas, and 30,23 oxygene ; or 27,01 nitrogene, and 64,54 oxygene: and the nitrogene in nitric acid, is to the oxygene as i to 2,389.

• My ingenious friend, Mr. James Thomson, has communicated to me some observations relating to the composition of nitrous acid (that is, the orange-coloured acid), from which he draws a conclusion, which is, in my opinion, countenanced by all the facts we are in possession of, namely, that it ought not to be considered as a distinct and less oxygenated state of acid, but simply as nitric or pale acid, holding in solution, that is, loosely combined with, nitrous gas*.” P. 29.

6* In a letter to me, dated Oct. 28, 1799, after giving an account of some exi periments on the phlogistication of nitric acid by þeat and light, he says, “ It was from an attentive examination of the manner in which the nitric acid was phlar gisticated in these experiments, that I was confirmed in the suspicion I had long before entertained, of the real difference between the nitrous and nitric acids. It is not enough to shew that in the nitrous acid, (that is, the nitric holding nitrous gas in solution), the proportion of oxygene in the whole compound is less than that entering into the composition of the nitric acid, and that it is therefore less oxygenated. By the same mode of reasoning we might prove that water, by absorbing carbonic acid gas, became less oxygenated, which is absurd. Should any one attempt to prove (which will be necessary to substantiate the generally received doctrine) that the oxygene of the nitrous gas combines with the oxygene of the acid, and the nitrogene, in like manner, so that the resulting acid, when nitrous gas is absorbed by nitric acid, is a binary combination of oxygene and nitrogene, he would find it somewhat more difficult than he at first imagined; it appears to me impossible. It is much more consonant with experiment to suppose that nitrous acid is nothing more than nitric acid holding nitrous gas in solution, which might, in conformity to the principles of the French nomenclature, be called nitrate of nitrogene. The difficulty, and in some cases the impossibility, of forming nitrites, arises from the weak affinity which nitrous gas has for nitric acid, compared with that of other substances; and the decomposition of nitrous acid (that is, nitrate of nitrogene) by an alkaline or metallic substance, is perfectly analogous to the decomposition of any other nitrate, the nitrous gas being displaced by the superior afinity of the alkali for the acid.

The result of our author's inquiries into this difficult subject is thrown into tables, showing the quantity of acid and gas in nitrous acids of different colours and gravities. In general, he finds these results coincide with those of Mr. Cavendish's experiments.

The second division of this essay contains • experiments and observations on the composition of ammonia, and on its combination with water and the nitric acid.' The little errors, that seem to have crept into the experiments of the first analysers of water, which influenced the results of the analysis of ammonia, led Mr. Davy to repeat the latter with more care; and he found that 100 parts of ammonia really contained 80 of nitrogen, and 20 of hydrogen. The analysis of these two ingredients is of importance, as, from the salt which they form on their union, the nitrat of ammonia, the source of the gaseous oxyd is produced. The proportions of these ingredients, in the crystallised salt, are 72.5 of the acid, and 19.3 in 100 parts of the alkali. The remainder is water, which differs according to the crystallisation: in the prismatic or fibrous nitrat, it is 12.1 in Ioo, and, in the compact nitrat, only 5.7...

The third division relates to the decomposition of nitrat of ammonia, the preparation of respirable nitrous oxyd, and its analysis.

ist. Compact, or dry nitrate of ammoniac, undergoes little or no change at temperatures below 260°.

The ammonia, the sales of thesined some and he monia,

“ Agreeable to this theory, the salts denominated nitrites are in fact triple salts, or ternary combinations of nitric acid, nitrous gas, and salifiable bases." , . This theory is perfectly new to me. Other chemists, to whom I have mentioned it, have likewise considered it as new. Yet in a subsequent fetter Mr. Thomson mentions that he had been told of the belief of a similar opinion among the French chemists.' P. 31.

• 2dly. At temperatures between 2750 and 300°, it slowly sublimes, without decomposition, or without becoming fluid.

3dly. At 320° it becomes fluid, decomposes, and still slowly sublimes; it neither assuming, or (nor] continuing in, the fluid state, without decomposition.

* 4thly. At temperatures between 340° and 480", it decomposes rapidly.

5thly. The prismatic and fibrous nitrates of ammoniac become fluid at temperatures below 300°, and undergo ebullition at temperatures between 360° and 400', without decomposition. ... 6thly. They are capable of being heated to 430° without decomposition, or sublimation, till a certain quantity of their water is evaporated.

7thly. At temperatures above 450° they undergo decomposition, without previously losing their water of crystallisation.' P.85.

We shall add the properties of the gas when separated: 100 cubic inches weigh 50.1 grains at temperature 50, and atmos! spheric pressure 37.

, a. A candle burnt in it with a brilliant filame, and crackling noise. Before its extinction, the white, inner flame became sur, rounded with an exterior blue one.

ob. Phosphorus, introduced into it in a state of inflammation, burnt with infinitely greater vividness than before.

c. Sulphur, introduced into it when burning with a feeble blue Hame, was instantly extinguished; but when in a state of active inflammation (that is, forming sulphuric acid) it burnt with a beautiful and vivid rose-coloured flame. .d. Inflamed charcoal, deprived of hydrogene, introduced into it; burnt with much greater vividness than in the atmosphere. ;.

e. To some fine twisted iron wire a small piece of cork was affixed: this was inflamed, and the whole introduced into a jar of the air. The iron burned with great vividness, and threw out bright sparks as in oxygene.

'f. 30 measures of it exposed to water previously boiled, was ra: pidly absorbed ; when the diminution was complete, rather more than a measure remained.

ig. Pure water saturated with it, gave it out again on ebullition, and the gas thus produced retained all its former properties.'

It was absorbed by red cabbage juice ; but no alteration of colour took place.

• 1. Its taste was distinctly sweet, and its odox slight, but agree able.

•j. Įt underwent no diminution when mingled with oxygene or nitrous gas.' P. 87. . This gas is produced by the heat of 440: at the degree of 800 it is decompounded into water, nitrous gas, nitrous acid, and nitrogen. At still higher degrees of heat the attraction of the nitrous gas for nitrogen is destroyed, and that of oxy: gen for. hydrogen augmented, producing water and nitrous

sen for hrous gasfotill higher water, niti 440: a

* for hydrogen er nitrogen is lees of heat rinitrous acid,

vapour; but we need not pursue the subject more minutely. In decompositions at the temperature of 800°, there is a vivid separation of light; and at 400°, heat is generated or evolved.

In the preparation of the gaseous oxyd, our author prefer's, the fibrous nitrat of ammonia; and the gas should rest till an acidulous vapour subsides. For the particulars of the preparation, we must refer to the work; but we may add, that this stimulus is very cheap; since each dose may be prepared for 2 di Gin is dearer.

In the fourth division, Mr. Davy gives an account of the ex, periments by which the proportions of oxygen and nitrogen, combined in nitrous gas, were estimated. He gives the analysis of nitrous gas by charcoal and pyrophorus, with some additional observations on the combustion of bodies in nitrous gas, and on its composition. This gas is decomposable by most of the combustible bodies ; but the analysis by charcoal is much the most accurate method of determining the respective quantities of nitrogen and oxygen, especially when corrected by calculations derived from the other methods: the proportions are 0.56 and 0.84. These differ greatly from those fixed by Lai voisier, arising from some errors in his fundamental experia ments on the decomposition of nitre by charcoal.

Nitrous gas, our author finds, is soluble in pure water : 100 parts of the latter dissolve 11.8 of the gas, but do not retain it in a boiling heat; and the gas does not influence the taste of the water. Spring water absorbs much less of the gas than pure water, on account of the quantity of earthy salts. The quantity of gas which disappears is greater than that which the water holds in solution, as a part is united to the oxygen of the atmospheric air combined with the water, while an increased residuum arises from the disengagement of the nitrogen of this air. There are some varieties in the quantity, absorbed by water containing other gases; but this part of the subject is not clear, or indeed important.

Mr. Davy next proceeds to the absorption of nitrous gas by a solution of pale green sulphat of iron. This inquiry is ex. tended to an unreasonable minuteness. The green sulphat alone appears to attract nitrous gas; and the common sulphat absorbs it only in proportion as it contains the green: the red has little or no affinity to the gas. The solutions of green sulphat of iron dissolve nitrous gas in quantities proportional to their concentration, without effecting any decomposition at common temperatures. The attractions which occasion this solubility would lead us too far. Mr. Davy next considers the absorption of nitrous gas by a solution of green muriat of iron, by a solution of nitrat of iron, and by other metallic solutions. These remarks are followed by an account of the action of sulphurated hydrogen on a solution of green sulphat of iron

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