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• A strong effervescence with much heat took place. The globule ' in a few minutes had enlarged to five times its former dimen'fions, and had the appearance of an amalgam of zinc; and me'tallic chrystallizations shot from it as a centre, round the body

of the salt. They had an arborescent appearance; often became

coloured at their points of contact with the muriate ; and, when - the connexion was broken, rapidly disappeared, emitting ammo

niacal fumes, and reproducing quicksilver.' Carbonate of anmonia gave the same result; only that a manifest decomposition of the acid, and production of carbonaceous matter, accompanies the other phenomena in this case. The bases of the alkalis and earths, united with mercury, and exhibited in this state to ammonia, supplied the place of electricity, and formed an amalgam of the bases of ammonia and mercury. A little of the basis here used for the purpose of deoxygenating the ammonia, adhered to it in the amala gam; but, independently of this consideration, our author seems to think, that the experiment in question unites more of the ammoniacal basis to mercury, than the procefs of deoxygenation by clectricity. He does not mention, though we must presume, that, in this ingenious and beautiful experiment, the fixed alkalis or earths are reproduced..

The singular amalgam discovered by the Swedish chemists, may thus be obtained with great ease, either by the agency of electricity, or by double elective affinity. But our author preferred the former method, because it is not attended with the admixture of any third substance, giving the amalgam composed solely of mer. cury, and the bases of ammonia. Having procured a sufficient quantity of it in this way, he examined it by various fimple and satisfactory trials. Its principal properties are the following. At 70° or 80° this body has the consistence of butter ;-at the freeze ing point it hardens and chrystallizes ;-it is not quite three times heavier than water. In water, it absorbs oxygen, caufing hydrogen gas to be evolved. In air, it likewise absorbs oxygen ; and, in both cases, ammonia and quicksilver are reproduced. In sul. phuric acid, it becomes coated with sulphate of ammonia and sulphur. Sixty grains of mercury are amalgamated by zbo part of a grain of the compound basis, or ricco of the weight of the mercury. The very small proportion in which the basis thus unites with mercury, oppotes an obstacle to the separation of the two bodies, and the exhibition of the .basis of ammonia, which all Mr Davy's industry and Ikill have not been able to surmount: for, lo very minure a portion of oxygen is sufficient to regenerate the ammonia, and so greedily does the basis attract oxygen, wherever it may be found, that no manipulation has hitherto been attempted, in which, either by means of moisture, air, or some other body containing oxygen, a reproduction of the ammonia, did not take place, notwithstanding every precaution. We refer our readers to the paper itself, for an interesting narrative of the trials made by the ingenious and persevering author, to attain the highly important object in question. The difficulties which frustrated his endeavours, are all resolvable into the general statement just now given ; and we have great hopes that they will hereafter be overcome, either by this indefatigable inquirer himself, or by some other chemists, whom his highly commendable publication of his experiments, in their present state, may lead to happier results.

containings

Mr-Davy concludes his valuable paper with some general fpeculations concerning the theory of alkaline and earthy bodies, as elucidated by the discoveries which we have just now, and on two former occasions, considered. His observations are always inge- •, nious; and whatever comes from so great a discoverer, one fo. strict in his experimental investigations, and so successful in generalizing them, ought to be received with singular respect. Nevertheless, we shall not follow him through the whole of his queries and reflections, highly ufeful as they are likely to prove. We Shall only state what we conceive to be the legitimate inferences, from his experiments, and then notice a few of his most prominent obfervations. It is clearly proved, that the fixed aikalis, and the alkaline earths, are metallic oxides ; and the proportion of their bases are nearly as well ascertained as those of several metals known for ages to philosophers, and in common life. Thac alumine, zercone, glucine, and filex, are also metallic oxides, seems highly probable ; but their decomposition has not yet been fo completely effected as to render this point altogether certain ; and, respecting the metals which seem to constitute their bases, we can scarcely be said to know any thing with precision. It is demonstrated, that ammonia is a compound of oxygen, with hy. drogen and nitrogen; and that when the oxygen is removed, the hydrogen and nitrogen are capable of entering into a true chemical union with mercury, forming a substance in all respects similar to the amalgams of that body with other metals. It is highly probable, that the hydrogen and nitrogen are united together as a chemical compound, which thus unites with mercury; and that the same compound unites with oxygen to form ammonia. The appearance of amalgamation, as well as the analogy of the other alkaline bodies, leads us to suspect that this compound basis is truly of a metallic nature, and that the volatile, like the fixed alkalis and the alkaline earths, is a metallic oxide ; but this bafis has not yet been separately exhibited. Such, in general, is the state of our knowledge upon the constitution of the alkalis and earths, as extended by the late wonderful discoveries; and such is the line to

be

be drawn between what we have strictly learnt as physical truths, and what we have been taught to conjecture upon evidence of a. lower nature than that of legitimate induction.

The last of thefe wonders, the conftitution of ammonia, gives. rise to various hypotheses. To account for the phenomena of a-. malgamation with mercury and reproduction of the alkali, three different theories have been stated. Mr Davy himself seems to think it possible, that hydrogen and nitrogen are both metals, aëriform at common temperatures, as zinc and mercury are when-ignited. Mr Berzelius suggests, that they may be simple bodies, not metallic, but forming a metal when united, without oxygen; and an alkali, when united and oxygenated. Mr Cavendish has sub-, mitted a third conjecture, that these gases, in their common form, may be oxides, which, when further oxigenated, become metallic. Of these hypotheses, or rather queries, (for it would be unfair to .. the distinguished and truly philosophical authors of them, if we did not remind our readers that they have only been thrown out as. hints for future investigation), we should prefer the last; at least, in point of beauty and simplicity, it feems to have some advantage. But the feafon, we trust, is not far diftant, when we shall be enabled to try their comparative merits by another and a higher criterion.

The fingular facts which abound in the decomposition of ammonia, appear to strike Mr Davy as capable of leading to some degree of fcepticism refpecting the phlogistic and antiphlogistic theories; but he clearly shows that they leave the latter in a much better state than the former. He thinks them not easily reconciled to either; but with less difficulty to the antiphlogistic theory. If,' says he,' we assume the phlogistic hypothesis, then • we must affume, that nitrogene, by combining with one fourth

of its weight of hydrogene, can form an alkali, and, by com• bining with one twelfth more, can become metallic. If we rea« son on the antiphlogistic hypothesis, we must assert, that though 'mtrogene has a weaker affinity for oxygene than hydrogene (has), ' yet a compound of hydrogene and nitrogene is capable of de-. • composing water.' And he proceeds to show that the latter difficulty is the lefler one; and though he thinks it cannot be wholly removed, it may yet be diminished by chemical analogies; for example, by the superior inflammability of certain compounds, and the greater oxidability of alloys. We confess, that, to us, this difficulty seems by no means greater than several others not alluded to by Mr Davy; and we advert more particularly to the case of nitrous gas. Nitrogene, by combining with a certain proportion of oxygene, acquires so great an attraclion for more oxygene, that it takes it from nitrogene. Here is the very difficulty

ftated

ftated by our author, as involved in the antiphlogistic explanation of the decomposition of ammonia ; with this difference, that it is rather more hard to conceive how nitrogene with oxygene should take oxygene from nitrogene, than it is to conceive how nitrogene with hydrogene should take oxygene from hydrogene. The difficulty, we presume, is generally explained by saying, that the various degrees of latent heat contained in the same body vary its elective affinities. In fact, this difficulty belongs to a class of phenomena by no means of small extent. Carbon, for example, takes oxygen from phosphorus in reducing phosphoric acid ; and phosphorus decomposes carbonic acid. In like manner, sulphur reduces the oxides of several metals, which, in their reguline state, decompose sulphuric acid. We are far from saying that these phenomena are unattended with difficulty, on whichever theory we attempt to explain them. We would only suggest, that the discovery of the Swedish chemists, and its extension by Mr Davy, has added no new difficulty to the list, and offers no new anomaly to the modern theory.

Besides the experiments which form the body of the paper now before us, there are various important facts introduced incidentally. We have already noticed the decomposition of carbonic acid by the electric agency. There are some very interesting experiments on the constitution of the muriatic acid, which we trust may hereafter lead to a full solution of that problem. A long and curious note is also given upon the discovery of Messrs Gay, Lusac and Thenard, that the alkalis may be decomposed by the action of iron in a state of ignition ;-a new example, by the way, of the difficulty above mentioned; for potassium and sodi. um easily reduce the oxides of iron. But we should give a very unsatisfactory account of this curious matter, were we to take it at second hand. We hope to be able, in our next Number, to lay before our readers an abstract of the history of the discovery from the authors themselves.

Art. XI. Memoirs of John Lord de Joinville, Grand Seneschal

of Champagne. Translated by Thomas Johnes, Esq. At the Hafod Press. 1807.

The Memoirs of Joinville have always held a high rank among

writings of that class. They are indeed entitled to particular notice, as the earliest specimen of history in a modern language; except Ville-Hardouin, which is not a very common book; and the French original of William de Nangis, which is still less known. From the dissolution of the Roman empire to the 13th century, the charge of perpetuating past transactions fell to the share of narrow and bigoted monks, who treat the af. fairs of mankind only by the way; and treat, at large, of no. thing but their own spiritual squabbles, or the miracles of their saints. Those who praise the natural simplicity of antient writers, and regret their lively portraiture of manners, are very partially acquainted with the great mass of chroniclers. No man has ever turned over, with weary patience, the folio pages of the :: Benedictine collection of French historians--of Muratori's Scriptores Rerum Italicarum--of Reibomius, Frehorus, or Urstisiuswithout acknowledging the worthlessness, generally speaking, of these annalists, in any other view than as dry compilers of public transactions. Yet it is a common piece of affectation, in those who pretend to be learned, to deride all modern abridgements of history, and to send the student at once to the fountain-head, in which, if we may trust these counsellors, he will find a stream more full, as well as more pure, fresh from truth and nature, without any sophistication of philosophy. But, without the assistance of those who have brought together and arranged whatever is important in the records of antient times, we are bold to say, that little profit indeed could be reaped by their study, unless by those who should undergo the same labour with the same ability.

still

The greater part, by far, of those who wrote history before the 13th century, were not only ecclesiastics, but men separated from secular concerns. We have just noticed (and without exaggeration, though sarcastically) the effect which their condition had upon their tone of writing. During the midnight of Europe, scarce any layman possessed competent learning for the easiest literary work, and no modern language was applied to any species of composition. A few songs and romances appear in the French and Provençal, in the 12th century; and, if Mr Southey is not deceived, the Spanish poem of the Cid, which he has lately published, is of the same age. In the 13th century, the twilight became brighter: a good deal of French prose of that time is extant; chiefly indeed laws and law-books, besides the history of Ville-Hardouin. Joinville, the companion of St Louis in his youth, from 1248 to 1254, finished, in his old age, these celebrated Memoirs. They are dedicated to Louis Hutin, eldest son of Philip le Bel; and, at the date of the dedication, the author must have been more than fourscore years old. Gibbon imagines him, indeed, to have been not less than ninety; but this is founded upon a miscalculation of his age. He could not have been born later than 1227, ince he was a knight in 1248 ; but there

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