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former dimensions, and had the appearance of an amalgam of zinc; and metallic crystallizations 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 ammoniacal fumes, and reproducing quicksilver.' Carbonate of ammonia 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 amalgam; 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 process of deoxygenation by electricity. 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 mercury, and the bases of ammonia. Having procured a sufficient quantity of it in this way, he examined it by various simple and satisfactory trials. Its principal properties are the following. At 70° or 80° this body has the consistence of butter ;-at the freezing point it hardens and crystallizes;-it is not quite three times heavier than water. In water, it absorbs oxygen, causing hydrogen gas to be evolved. In air, it likewise absorbs oxygen; and, in both cases, ammonia and quicksilver are reproduced. In sulphuric acid, it becomes coated with sulphate of ammonia and sulphur. Sixty grains of mercury are amalgamated

by.

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part of a grain of the compound basis, or too of

the weight of the mercury

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This valuable paper our author concludes with some general speculations concerning the theory of alkaline and earthy bodies, as elucidated by the discoveries which we have now considered. "His observations," say the writers in the Edinburgh Review, "are always ingenious; and whatever comes from so great a discoverer, one so 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 useful 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 observations. It is clearly proved, that the fixed alkalis, and the alkaline earths, are metallic oxides; and the proportion of their bases is nearly as well ascertained as those of several metals known for ages to philoso phers, and in common life. That alumin, zircon, glucine, and silex, are also metallic oxides, seems highly probable; but their decomposition has not yet been so 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 hydrogen 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

*See Phil. Trans. Part II. 1808.

metallic

metallic nature, and that the volatile, like the fixed alkalis and the alkaline earths, is a metallic oxide; but this basis 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 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 these wonders, the constitution of ammonia, gives rise to various hypotheses. To account for the phenomena of amalgamation with mercury and the 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 submitted a third conjecture, that these gases, in their common form, may be oxides, which, when further oxygenated, become metallic."

The labours of sir Humphry Davy in this department of science have been unwearied, but they have been crowned with a degree of success, and with discoveries of such importance as no one could have anticipated. "Let us," says the writer already referred to, "consider what we should have said, had such a contribution to chemical knowledge (as that in the Phil. Trans. 1809) fallen in our way three years ago had we for instance heard, that the basis of the boracic acid had been discovered, that hydrogen had been detected in sulphur and phosphorus, and oxygen in azote? The whole world of letters would have been in commotion, and it would have been universally allowed, that, since the establishment of modern chemistry, no such steps had been made towards its perfection. If we now think less. of these improvements, or even receive them with coldness,

it

it is because we have been spoiled with the abundance of capital discoveries, in which we have been revelling-and it is Davy himself who has spoiled us. His grand and numerous inventions, together with the two unexpected and important steps made by the French and Swedish chemists, have, for a while, so completely satiated the curiosity of the scientific world, that scarcely any new fact would now excite astonishment." Phil. Trans.-Edin. Review.-Murray's Chemistry.

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