# Digitale Ausgabe

 TEI-XML (Ansicht) Text (Ansicht) Text normalisiert (Ansicht)
##### Ansicht
 Textgröße Originalzeilenfall ein/aus Zeichen original/normiert
##### Zitierempfehlung

Alexander von Humboldt, Louis Joseph Gay-Lussac: „Experiments on the Eudiometrical Means, and on the Proportion of the Constituent Principles of the Atmosphere“, in: ders., Sämtliche Schriften digital, herausgegeben von Oliver Lubrich und Thomas Nehrlich, Universität Bern 2021. URL: <https://humboldt.unibe.ch/text/1805-Experiences_sur_les-4-neu> [abgerufen am 23.03.2023].

##### URL und Versionierung
 Permalink: https://humboldt.unibe.ch/text/1805-Experiences_sur_les-4-neu Die Versionsgeschichte zu diesem Text finden Sie auf github.
Titel Experiments on the Eudiometrical Means, and on the Proportion of the Constituent Principles of the Atmosphere
Jahr 1806
Ort London
Nachweis
in: The Repertory of Arts, Manufactures, and Agriculture 8:45 (Februar 1806), S. 231–239; 8:46 (März 1806), S. 303–318; 8:47 (April 1806), S. 365–381; 8:48 (Mai 1806), S. 449–461.
Beteiligte Louis Joseph Gay-Lussac
Sprache Englisch
Typografischer Befund Antiqua; Auszeichnung: Kursivierung; Fußnoten mit Asterisken; Schmuck: Initialen, Kapitälchen; Tabellensatz.
Identifikation
Textnummer Druckausgabe: II.32
Dateiname: 1805-Experiences_sur_les-4-neu
Statistiken
 Seitenanzahl: 55 93388

Weitere Fassungen
Expériences sur les moyens eudiométriques, et sur la proportion des principes constituans de l’atmosphère (Paris, 1805, Französisch)
Versuche über die eudiometrischen Mittel und das Verhältniß der Bestandtheile der Atmosphäre (Berlin, 1805, Deutsch)
Versuche über die eudiometrischen Mittel, und über das Verhältniss der Bestandtheile der Atmosphäre. Vorgelesen in der ersten Klasse des National-Instituts am 21sten Jan. 1805 Zweiter Teil: Ueber die Natur der Luft, welche man aus dem Wasser erhält, und über die Wirkung des Wassers auf reine und auf vermischte Gastarten (Halle, 1805, Deutsch)
Experiments on the Eudiometrical Means, and on the Proportion of the Constituent Principles of the Atmosphere (London, 1806, Englisch)
|231|

Experiments on the Eudiometrical Means, and on the Pro-portion of the Constituent Principles of the Atmosphere.By Messrs. Humboldt and Gay-Lussac. From the Journal de Physique.

IF philosophers and chemists are at present agreed re-specting the nature of the constituent principles of theatmosphere, they are not yet so with regard to theirabsolute quantity. Since Scheele and Lavoisier, whohad found twenty-seven hundredths of oxygene in the air,numerous experiments, for which we are indebted to |232| Messrs. Cavendish, Marti, Berthollet, Fourcroy, andDery, have greatly modified this proportion, by fixingit at between twenty and twenty-three hundredths. Ne-vertheless it must be admitted that these proportions arestill far remote from that degree of accuracy which thepresent state of Science allows of; or, if these limits arewell established, it must be concluded that the atmosphereexperiences considerable oscillations in its composition.Although with respect to most chemical phenomena, it isnot necessary that we should have an accurate knowledgeof the absolute quantity of its principles, this knowledgeis not less interesting in itself, than important with re-gard to the history of our globe. If all the facts of geo-logy tend to prove that the earth is no more what it hasformerly been; that the highest mountains have beencovered with water, and that the Arctic regions havenourished animals which at present are to be found onlybetween the tropics, these very changes prove of whatgreat utility it would be to future ages actually to ascer-tain the physical state of the globe at the present day;and even though the grand catastrophes which it has al-ready experienced should never more be reiterated, it ispossible that it may undergo gradual modifications whichman would not be able of himself to appreciate, unlesshe found incontestible documents in the annals of science.It would therefore be of the highest importance to fix inan authentic manner the grand phenomena of nature,which are to be supposed subject to variation; such asthe intensity of the magnetic forces, the elevation of thebarometer at the level of the sea, that of the sea itself,the medium temperature of every climate, and the pro-portion of the constituent principles of the atmosphere.We have directed our attention to the latter question, andalthough we have not yet solved it in a manner entirely |233| satisfactory to ourselves, we venture to give an accountof the commencement of the investigation which we haveundertaken upon this subject, and the researches to whichit has led us. But the eudiometrical means which must serve to de-termine the proportions of the constituent principles ofthe air are not all susceptible of equal precision, and somedistinguished chemists give the preference to a meanswhich is rejected by others. It therefore was indispensa-bly necessary that we should put to the trial the knowneudiometrical methods, in order that we might be ena-bled properly to appreciate their value; for we are wellconvinced that accuracy in experiments depends less uponthe faithful observation of the divisions of an instrument,than upon the accuracy of the method itself. Althoughthe nitrous gas appears indeed at first to be the most un-certain eudiometric means that can be chosen, we haveconvinced ourselves that by combining its action withthat of the sulphate of iron, or of the oxygenated muria-tic acid and of potash, it is capable of indicating withgreat precision the quantity of oxygene contained in theair. All the eudiometrical means would give the sameresults, if we were equally acquainted with them all, andit is only because it is very difficult to make all the cor-rections they allow of, that we naturally give the prefer-ence to such as present less occasion for them, althoughthey are not always the most simple in their use. Weshall therefore first give an account of the eudiometricalresearches with which we have occupied ourselves, andthen apply them to the analysis of the atmospheric airand of that obtained from water under different circum-stances, or placed in contact with it. We find it neces-sary again to repeat that we shall not treat the questionwhich we have proposed to ourselves in so extensive a |234| manner as it merits. Compelled to break off our re-searches before we were able to bring them to their ter-mination, our purpose is only to give an account of theirprincipal results. During nearly two months since thetime that we commenced them in one of the laboratoriesof the Polytechnic-school at Paris, we pursued them, inspite of the coldness of the weather, which is very dis-agreeable in researches of this kind, with so much thegreater assiduity, as M. Humboldt found a peculiar in-terest in them. In the year 6, he had presented to theInstitute two memoirs on the analysis of the air, whichcontain a great number of experiments, which he nowconsiders (it is he himself that avows it) not only as veryinaccurate, but also as very justly controverted by Mr. Davy, and by a chemist with whose particular friendshipwe are both honoured, namely, M. Berthollet. Zealousfor the advancement of science, M. Humboldt, when hecommenced his researches, wished to substitute in theplace of those investigations of his early youth, othersfounded upon more solid foundations, and as he desiredto have me for his associate in them; I ought to considermyself the more highly honoured by his proposition fromour having been, since his return from the tropics, linkedtogether in the closest bonds of friendship.

Observations on several of the Eudiometric Means.

* The absorption of which we mean to speak in this place is inde-pendent of that of oxygene by the sulphuret, which is thereby con-verted into sulphate. But as the sulphuret absorbs the oxygenewhich the water holds in solution, it will very probably happen thatthe water will be able to absorb a larger quantity of azote; so that ifwe employed a solution made with cold water, and very recently pre-pared, there would be a still greater diminution of volume than thatwhich is owing to the absorption of the oxygene. We say very proba-bly; for we have not yet made the experiment.
|238| think, therefore, that the difference between the resultsof Messrs. Marti and Berthollet may be explained by thedifference of the circumstances under which they ope-rated; but it appears to us, that M. Marti believedthat it was the nature of the sulphuret to absorb azote,whereas it does not absorb it all, but rather prevents thewater with which it has been boiled from absorbing asmuch as it would do without it.
Thus if we take care to dissolve the sulphurets in coldwater, and leave them for some time in contact with azoteor with air, we may employ them with advantage for theanalysis of the atmosphere. We shall however observe,that as they are attended with the inconvenience of re-quiring a great length of time before their action is com-pleted, we are obliged to have recourse to the correc-tions of the thermometer and barometer, which often arevery uncertain. The best way of remedying this incon-venience is undoubtedly to follow the method of Messrs. Berthollet and Marti, which consists in placing, for com-parison, upon water a determinate quantity of air, inorder to judge, from its variations of volume, of that ofthe air which we analyze; but this method has not ap-peared to us to be attended in practice with all the ad-vantage which it seems to promise. We must still remark with regard to all the eudiome-trical means, where the absorbing substance is solid orliquid, that if we commit an error, either in observingthe divisions of the instrument, or in the appreciation ofthe uncertainties of the method, this error necessarilyfalls altogether upon the quantity of oxygene; and sincewith all possible exactness we cannot answer for itsamounting to much less than a hundredth part, it wouldfollow that the proportion of oxygene contained in theair cannot be determined within this quantity. In fact,we find that chemists who have employed such means |239| have found very considerable variations in the quantity ofoxygene of the air; and M. Marti himself, who appears tohave made a great number of experiments with the alcalinesulphurets, and who was acquainted with the precautionswhich they require, fixes it between 0,21 and 0,23. Weshall see hereafter that the eudiometrical means, in whichthe substance which combines with the oxygene is gase-ous, admit of a much greater precision. As we had proposed to ourselves from the commence-ment of our investigation, to ascertain whether the eudi-ometer of Volta was fit to be employed for the analysisof the air, we principally directed our attention to it.This instrument has been accused of being fallacious, ofindicating too small quantities of oxygene in the air;but it appeared to us that supposing it required correc-tions, we might by appreciating them, as well as thelaw of their variations, render it very exact and conve-nient. With this view we proposed to ourselves the fol-lowing questions: 1. When a mixture of hydrogene gas and oxygene gasis inflamed in Volta’s eudiometer, can the absorption ofone of the gases be complete? 2. Is the product of their combination of a constantnature? 3. What is the exact proportion of the two gases forforming water? 4. What are the limits of error that Volta’s eudiometeradmits? We must examine these four questions in succession,but first of all we think it incumbent upon us to give anaccount of the manner in which we prepared the gaseswhich we employed in our experiments. to be continued in our next
|303|

Experiments on the Eudiometrical Means, and on the Pro-portion of the Constituent Principles of the Atmosphere.By Messrs. Humboldt and Gay-Lussac.

(Continued from Page 239.) THE oxygene gas we obtained from the super-oxy-genated muriate of mercury. To obtain it we employeda glass retort, to which had been soldered, by the flameof a lamp, the curved tube through which the gas was topass; and, in order that we might have it as exempt fromazote as possible, we filled the retort about one-fourthwith water. This water being entirely reduced to va-pour before the decomposition of the salt, soon expelledall the air out of the retort; but, in order to prevent theabsorption which would have taken place before the dis-engagement of the oxygene gas, we plunged the ex- |304| tremity of the tube in a saucer filled with mercury, whichwe removed as soon as the gas began to be disengaged.In order that the oxygene may not, passing through thewater, expel azote from it, we convey it directly intothe upper part of the recipient which is to receive it, bymeans of a tube bent at a right angle, which at the oneend ascends to the upper part of the recipient, and at theother is adapted to the first tube by means of a corkstopper, common to both. This process, which is verysimple in its application, is particularly advantageous forthe gases which are soluble in water, such as the carbonicacid gas, the azote oxyd gas, &c. We obtained our hy-drogene gas by decomposing water by means of zinc andmuriatic or sulphuric acid diluted with about six parts ofwater: we took care to fill exactly with acid the vesselfrom which the gas was to be disengaged, and not tomake it pass through the water; but notwithstanding allthese precautions, our oxygene left with the sulphuretfour thousandth parts of azote, and the hydrogene, ana-lysed by other means, shewed six thousandths. Afterthese elucidations let us proceed to the questions whichwe have proposed to ourselves to resolve, beginning withthis: When we inflame a mixture of oxygene and hydrogenegas in the eudiometer of Volta, can the absorption of oneof the gases be complete? In order to ascertain whether all the oxygene or all thehydrogene could be entirely destroyed, we thought thatif two gases were perfectly pure, or if we knew their de-gree of purity, and that their absorption must be com-plete, we should be able to find the same proportion forthe principles of water, whether the hydrogene or theoxygene were predominant. In fact, by detonatingmixtures of 300 parts hydrogene and 100 oxygene, and |305| of 200 of the first and 200 of the second, in which thehydrogene and oxygene alternately predominate, andmaking the corrections due to the impurity of the gases,we obtained very nearly the same proportion. Althoughthe absorption of the two gases might be complete, itwere however possible that the proportions obtained, inmaking them alternately predominate, might not be iden-tical, and this would be the case if, according to the pre-dominance of either of the gases, there were formed anoxygenated or hydrogenated water; but since the propor-tions have become identical, it must necessarily be con-cluded, that the hydrogene and the oxygene were entirelyabsorbed. But though the absorption of the two gasesmay be complete under certain circumstances, it mustnot be supposed that it is so with any quantities; there arenot only such proportions of hydrogene and oxygene, orof their mixture with azote, or even with any other gas,that it is impossible to inflame them by means of theelectric spark; but there are also others with which theinflammation having been commenced, stops before thecombustion is completed. We proceed to cite ex-periments to this effect, which appear to us to be con-clusive. We mixed 100 parts of hydrogene with 200, 300—900of oxygene, and inflamed them by the electric spark:with these different proportions the absorption constantlyamounted to 146 parts; but with 1000 of oxygene it wasat once reduced to 55; with 1,200 and 1,400 it was re-duced to 24 and 14, and with 1,600 it was reduced to 0;that is to say, no inflammation took place. These dif-ferent results are exhibited in the following table. |306|
 Hydrogene. Oxygene. Absorption. 100 ‒ ‒ ‒ 200 ‒ ‒ ‒ 146 100 ‒ ‒ ‒ 300 ‒ ‒ ‒ 146 100 ‒ ‒ ‒ 600 ‒ ‒ ‒ 146 100 ‒ ‒ ‒ 900 ‒ ‒ ‒ 146 100 ‒ ‒ ‒ 950 ‒ ‒ ‒ 68 100 ‒ ‒ ‒ 1000 ‒ ‒ ‒ 55 100 ‒ ‒ ‒ 1200 ‒ ‒ ‒ 24 100 ‒ ‒ ‒ 1400 ‒ ‒ ‒ 14 100 ‒ ‒ ‒ 1600 ‒ ‒ ‒ 0 *
What is striking in these different experiments is to see,1, a constant absorption, with very different proportions,change suddenly into a decreasing absorption; 2, thecombustion of hydrogene gas which had commenced,stop before it was completed; 3, that there are such pro-portions of hydrogene and oxygene as cannot be in-flamed. These different phenomena will be in somemeasure explained in the sequel; but in the mean timewe shall remark, that there are even very extended pro-portions with which the combustion of the hydrogene gasmay be complete. The above-mentioned phenomena are not peculiar tothe hydrogene and oxygene gases mixed together, underthe circumstances of which we have been speaking: theyalso take place when we inflame 100 parts of oxygenewith 200, 300—1000, &c. of hydrogene; only it thenhappens, that the term when the absorption ceases to beconstant is more remote; and to comprehend the reason
* The absorptions 68, 55, 24, and 14, are possibly not exact withintwo or three hundredths, for our instruments being too small for thecorresponding proportions, we were obliged to measure them seve-ral times; but this is of no moment with respect to the phenomenonin general.
|307| of this it is sufficient to observe, that in this case theredisappear about 300 parts by the inflammation, whereasthere disappeared only half the quantity in the precedingexperiments.
|365|

Experiments on the Eudiometrical Means, and on the Pro-portion of the Constituent Principles of the Atmosphere.By Messrs. Humboldt and Gay-Lussac.

(Continued from Page 318.) NOW as we have made a great number of experi-ments which prove, that when we employ them alter-nately in excess we constantly, obtain the same propor-tions, it follows, that the combustion of hydrogene gas isof an uniform nature. The Galvanic phenomena of thedecomposition of water seem however to prove that wa-ter is capable of oxygenating or hydrogenating itself;and it is upon this supposition that Messrs. Laplace and Berthollet have accounted for the singular experiment ofthe decomposition of water by two metallic wires im-mersed at one end in this liquid, and communicating bythe other with the two poles of a Galvanic pile. Butwithout wishing to controvert this explanation, whichappears to us the most satisfactory that has hitherto beenoffered, we shall observe that the complete absorption ofthe hydrogene at one of the wires, and of the oxygeneat the other, proves that the water does not becomeoxygenated or hydrogenated, because, in order to be- |366| come so, it would be necessary that it should absorb oneof the gases in a proportion greater than that requiredfor the composition of water. If therefore it absorbsoxygene and hydrogene in exact proportions for formingwater, it must be concluded that the properties of oneof the gases are neutralized by those of the other. Ac-cordingly, in the circumstances of which we are treat-ing, the water might become instantaneously oxygenatedat one of the wires, and hydrogenated at the other; butthe two gases, being deprived of elasticity, and in exactproportions, must soon enter again into combination. If it is well demonstrated that, under given circum-stances, hydrogene or oxygene may be completely ab-sorbed, and, if it is equally so, that the product of theircombination is constant, nothing more remains to bedone, in order to solve the third question, which we haveproposed to ourselves, than to determine the propor-tions of oxygene and hydrogene which constitute water. To 100 parts of oxygene gas we added 300 parts ofhydrogene gas; and after having inflamed them by theelectric spark, we obtained in twelve experiments thefollowing residues:
 100,8 101,0 102,0 101,4 101,7 102,0 100,5 102,0 101,0 101,0 101,5 101,5 The mean term of which is ‒ ‒ 101,3
Thus 100 parts of oxygene, supposed to be very pure,required 98,7 of hydrogene: but on placing our oxy-gene gas in contact with sulphuret, we found that it hadall been absorbed within about 0,004; hence it follows,that 99,6 of oxygene absorbed 199,1 of hydrogene, orthat 100 absorbed 199,89, or, to use round numbers, |367| that 100 of oxygene requires 200 of hydrogene for theirsaturation. In the preceding experiments it was the oxygene thatdisappeared. Let us now reverse the experiment, by in-flaming a mixture of 200 parts of each gas; the residueof the different inflammations will be the following:
 101,5 102,0 101,5 101,3 102,0 102,3 102,2 101,0 102,0 102,0 101,0 102,0 Mean term ‒ ‒ 101,7 Mean absorption 298,8

Analysis of the Atmospheric Air by Volta’s Eudiometer.

 Analysis of the at-mospheric air. Of the air of the pit. Of the air of the highestpart of the building. 200 atmosph. air. 200 atmosph. air. 200 atmosph. air. 200 hydrogene. 200 hydr. 200 hydr. 126 air absorbed. 121,5 abs. 122,5 abs. 21 oxygene. 20,2 oxyg. 20,4 oxyg.
|449|

Experiments on the Eudiometrical Means, and on the Pro-portion of the Constituent Principles of the Atmosphere.By Messrs. Humboldt and Gay-Lussac.

(Concluded from Page 381.)

Of the Nature of the Air extracted from Water, and of theAction of Water upon the Gases, both pure and mixed.

This last portion of air is the purest we have yet ex-tracted from any water. |455| The volumes of each portion being known, calculationgives us for the purity of the air considered collectively28,7 of oxygene. The water of the Seine yielded on thesame day an air which was less pure by $$\frac{4}{1000}$$. Other-wise the two waters, that of melted snow and that of theriver, give a volume of air equal to nearly $$\frac{1}{23}$$ of theirown. These experiments upon snow-water and upon meltedice, which we design hereafter to vary in many ways,present considerations of great importance to the study ofmeteorology. Snow is nothing else than an aggregate ofsmall crystals of ice which are formed in the higherregions of the atmosphere, and yet these small crystalsmelted give a volume of air nearly twice as great as thatwhich the ice formed upon our rivers yields. Hence it is tobe concluded that when the water dissolved in the air con-geals into snow, it does not expel that large portion of airwhich it disengages in its congelation upon the surface ofthe earth, unless we might be allowed to suppose thatsnow retains between its small crystals a certain quantityof air which it absorbs as it melts; for it appearsthat it is principally at the moment of its congela-tion that water abandons the greater part of its air. The beautiful vegetation which surrounds the Gla-ciers, the rapid developement of plants when the snowmelts in the spring, and several phenomena which aresupposed to have been observed in agriculture and inbleaching, have led to the notion that the waters of ice,snow and rain, produced peculiar effects by a large quan-tity of dissolved oxygene which was evolved from them.The experiments which we have hitherto made do notseem favourable to these conjectures. There undoubt-edly exist wells, the waters of which contain air inferiorin purity to the atmospheric air, and we do not doubtthat these waters, charged besides with salts and car- |456| bonic acid, must have an influence upon vegetation andbleaching very different from that of snow-water. Butthe differences produced by distilled water exposed to theair, rain-water, snow-water and the water of the Seine,are not easily to be accounted for by the oxygene dis-solved in them, if we recollect that all these airs containwater of nearly equal purity, and that they contain it inalmost equal quantity. The phenomena of vegetation,like those of meteorology, are so complicated; they de-pend upon the concurrence of so many causes at once,that we must be very careful not to attribute to one whatis the effect of many. The experiments which we have recorded on the forcewith which the last particles of oxygene dissolved are re-tained by water, throw an additional light upon the statein which air exists in liquids. The specific gravity ofdistilled water and of that charged with air, being appa-rently the same, Mairan has concluded with reason thatthis air cannot be lodged in the fluids in an elastic state.The chemical phenomena confirm this opinion. If waterdeprived of its air by distillation, or by the air-pump,could be considered as a sponge the pores of which areempty, how should these pores not fill themselves on thefirst contact with atmospheric air? But this solution of airin water can be considered only as the effect of a chemicalaffinity; for how but by this affinity could the absorptionof the gases by the water deprived of air be so slow, andabove all, how else should the water dissolve one gas inpreference to another? How should water charged withone species of air abandon a part of it, as we shallsee hereafter that it does, to receive another of a differentnature? After having examined the air which may be extractedfrom water under different circumstances, we shall con-clude our Memoir with the experiments which we have |457| made in placing gases, both pure and mixed, in contactwith water. The gases which we employed were exactlyof the same volume, and the quantity of filtrated water ofthe Seine was nearly equal. After a space of from 6 to8 days, we not only measured the quantity of the volumesabsorbed, but we also analyzed the residues. This ana-lysis was the more necessary as one might often betempted to conclude from a very small change in the vo-lume of the gas placed in contact with the water, thatthe latter has no sensible action upon it, whilst the na-ture of the residue indicates that this action has beenvery strong, but disguised by the quantity of air evolvedfrom the water in lieu of that which has been ab-sorbed. Of all the gases, the oxygene is that which the waterof the Seine absorbs in the most considerable quantity.If we place in contact with this water, already chargedwith air, 100 parts of oxygene gas, 100 of azote, and 100of hydrogene, the oxygene gas will have diminished by40 parts when the two others have lost only 5 and 3 parts.But the real absorption of the oxygene gas is still muchmore considerable than its apparent diminution indicates.The 60 parts of residue, instead of being pure oxygene,contained 37 parts of azote and only 24 of oxygene; sothat the 100 parts of oxygene employed, had lost uponthe Seine water 77 parts, which had expelled 37 parts ofazote. Thus a river water which had been exposed fora long time to the atmosphere, and which might be con-sidered as saturated with air, absorbs a large quantity ofoxygene when it is presented to it. It takes it, withoutabandoning a portion of azote equal in volume to the oxy-gene absorbed. The action of water upon the volume of hydrogenegas appears to amount almost to nothing. The inequa- |458| lity of the results which we obtained prevent our sayingany thing concerning the slight changes which it mayundergo during their contact. The volume of pure azote gas diminishes upon thewater by between 2 and 3 hundredth parts; but the re-sidue is no longer pure azote: we discovered in it11 parts of oxygene which had been displaced fromthe water by 14 parts of azote. The azote therefore dis-lodges ozygene from the water, as oxygene dislodgesazote. The action is analogous, but the quantities ab-sorbed and dislodged are different. The contact of the river-water with a mixture of hy-drogene and oxygene gases was examined under vari-ous circumstances. Sometimes we mixed the two gasesin equal quantities, sometimes we caused one or the otherto predominate. The diminution of the volume of thegases is greater when the oxygene predominates; thatis to say, when we expose to the water a mixture of 200parts of oxygene with 100 of hydrogene. In all these ex-periments azote is again dislodged from the water. Inanalyzing the residuum of a mixture of equal parts of ox-ygene and of hydrogene, we found in 100 parts 20 partsazote, 50 hydrogene, and 30 oxygene. The greater theabsorption of oxygene was, the more azote we found tobe dislodged. Having mixed 400 parts of oxygene with200 of hydrogene, this volume was reduced upon Seinewater, in the space of ten days, from 600 parts to 562.If this residue had undergone no chemical change in itsproportions, if no other gas had been dislodged, itought to have contained 375 parts of oxygene and 187of hydrogene; but our analysis shewed it to contain 246azote, 142 hydrogene, and 174 oxygene. These experiments prove that hydrogene, which, whenplaced alone in contact with water, is not sensibly ab- |459| sorbed by it, is dissolved in it, and that in a very consi-derable proportion, when it is mixed with oxygene. Onthis subject a question of great importance to NaturalPhilosophy presents itself; namely, whether this hydro-gene absorbed by the water exists in it in the state of hy-drogene, or whether it combines in it with oxygene andso forms water. We have endeavoured to solve thisquestion by leaving a mixture of hydrogene and oxygenein contact with water recently deprived of all its air byebullition. After the space of 12 days, we distilled thiswater, and on analyzing the air disengaged from it, wefound the hydrogene to exist in it in such abundancethat we could inflame it in Volta’s eudiometer withoutadding to it any other gas. This experiment proves be-yond a doubt that the hydrogene absorbed is found againin the water. But did this water give up again the samequantity which it had absorbed? Would not this hydro-gene dissolved in the water unite with the oxygene if ithad been lodged in it for several months? We design tomake a long series of experiments upon this subject. Ifthe hydrogene and oxygene contained in the water couldcombine in it, we should be able more readily to conceivehow the hydrogene gas which rises from the surface ofthe earth is not to be discovered either in the air whichsurrounds us, or in the high regions of the atmosphereinto which we have ascended. We must recollect uponthis subject that having carefully examined rain-water,in order to discover hydrogene in it, we have ascertainedthat the air disengaged from this water did not containa quantity of it amounting to $$\frac{3}{1000}$$. We shall repeatthese experiments upon rain that has fallen in diffe-rent seasons, and particularly during storms. River water placed in contact with mixtures of gaseshas in general acted less upon the mixtures of oxygene |460| and azote than those of oxygene and of hydrogene.This result will appear the less surprizing if we takea general view of what takes place in these phenomena. We find that water has a continual tendency to placeitself in a state of equilibrium with the gases presentedto it. If we present oxygene to it, it abandons azote.If we place it in contact with azote, it abandons oxy-gene. If we present to it a mixture of oxygene andhydrogene, it absorbs a part of these two gases, and re-places them with azote. It every where tends to modifythe proportions of the air which it holds in solution ac-cording to the nature of the gases which are presented toit. Now the water of the Seine being charged with amixture of azote and of oxygene, it seems natural that itshould excite more action upon a mixture of hydrogeneand oxygene than upon that of azote and oxygene,which is analogous to the air which it holds in solution.In order to obtain an accurate idea of these phenomena,we shall make experiments upon water recently deprivedof air, by charging it with different gases both pureand mixed, and examining the action of this waterafter a long space of time; for frequently it is nottill after a long repose that nature is enabled to overcomethe obstacles which oppose themselves to the action of theaffinities. Here we shall conclude the account of the inquiries intowhich we have been engaged for several months past.The more extensive the field is which we purpose to ex-plore, the more strongly we feel the imperfection of thework which we now present to the public; but this sen-timent, so far from discouraging us, will only render usthe more assiduous in interrogating nature, in order thatwe may carry these researches to a higher degree of per-fection. |461| TABLE Representing the Analysis of the Air.