out success; for it seemed evident, that the fusion and action must come both at once from the electricity. Accordingly, having slightly moistened the surface of perfectly dry potash, so as to render it a conductor, he placed it on an insulated disc of platina, connected with the negative wire, and placed the positive wire upon the upper surface of the potash. A remarkable action now ensued; the salt fused at the wires, at the lower surface, without any effervescence; but, at the upper, with violent effervescence. At the lower surface, however, small globules like quicksilver were perceived to emerge, as the process went on, and many of them burnt with explosion and a bright flame; others, without explosion, became soon covered with a white crust on continuing exposed to the action of the air. The same phenomena were produced, when, instead of platina, other metals, as copper, gold, &c. were used, or plumbago, and even charcoal. The metallic globules, therefore, had nothing to do with the disc or wire employed; and the experiment was equally independent of the air, for it succeeded just as well in an exhausted receiver. Soda, when treated in like manner, exhibited similar results; but it was more stubborn, and required a much stronger electrical action. The globules too obtained from it were neither so fusible nor so inflammable; they were melted and burnt, however, by the heat produced in the course of the experiment. In both cases, the gas evolved at the upper or positive surface of the alkali, was found to be pure oxygen gas; nor was any given out at the negative surface, where the globules were formed, unless a superabundance of water existed there. When, on the other hand, one of the metallic globules was exposed, either to common air or oxygen gas, containing moisture in solution, a white film speedily was formed, which attracted moisture as it increased in thickness, and in a short time the whole globule was converted into this film, and dissolved. The solution from the potash globules was always found to be pure potash; those from the other, pure soda. When the air in which the globules are exposed is perfectly free from moisture, the process goes on imperfectly; for the crust which is first formed, remaining solid, defends the interior of the globule from the action of the air. When heat is applied, and the globules are exposed to oxygen gas in a close tube, they burn with great rapidity, and a brilliant white flame; the gas is absorbed; no other gas given out; and the oxyde which remains is a pure alkali.

Such is the decisive and most satisfactory evidence by which it is ascertained that the fixed alkalis are compounds of oxygen and metallic bases, or that they are in truth metallic oxydes. The metals are substances hitherto quite unknown to chemistry; and

Mr

Mr Davy, as might easily be imagined, lost no time in examining their peculiar properties. It is unnecessary to detail the various experiments which he has made for this purpose. We shall only follow him over the heads of this extensive and interesting subject. Our author first describes the properties of the base of potash; next, those of the base of soda; and then he investigates the proportions in which the oxydes, that is, the two alkalis, contain their metallic bases and oxygen. We shall reverse this order and consider the proportions in the compositions first.

In order to ascertain the proportion of oxygen to metal in the alkalis, Mr Davy employed this form of experiment. He introduced a small tray of gold, silver, and platina, into a tube con. nected at one end with a pneumatic apparatus and gazometer, and at the other drawn to a point, but suffered to remain open. Upon the tray, metallic globules of known weight were placed; the tube was filled with oxygen until the whole common air was expelled; it was then hermetically sealed at both ends; and heat being applied to the glass near the tray, the globule was burnt. The tube was then opened under water, or mercury, and the absorption ascertained. According to the result of one experiment, made with great accuracy, 100 grains of potash contains 86.7 of metal, and 13.3 of oxygen. And, according to another trial of the same kind, 100 grains contains 85.5 of metal, and 14.5 of oxygen; the mean of the two being 86.1 of metal and 13.9 of oxygen. Soda, in like manner, consists of 80 grains metal, and 20 oxygen, in 100 of alkali. The decomposition of water by the metallic bases, afforded another approximation. This gave, for potash, 84 parts metal to 16 oxygen, in the hundred; and for soda, 76 per cent. metal and 24 per cent. oxygen. Comparing these leading experiments with the mean results of a variety of others, our author infers, as a general medium of the whole, that potash contains about six parts of metal to one of oxygen; and soda about seven parts of metal to two of oxygen.

In examining the properties of the new bodies which these brilliant discoveries make us acquainted with, no small difficulty is experienced from their violent attraction for the constituent parts of almost all other substances. For oxygen in particular, (and almost every substance contains it), they have so infinitely greater an affinity than any other bodies hitherto discovered, that they not only become speedily oxydated, and changed back again to alkalis in the open air, but even in almost every fluid in which they are plunged for the purpose of preserving them. After repeated trials, Mr Davy found that naphtha, recently distilled, answered his object better than any thing else; and the globules, when taken from thence, were covered with a thin transparent

film

film of the fluid, which defended them from the action of the air, and at the same time allowed an accurate examination of their physical qualities. We shall first notice the qualities of the basis of potash. It resembles mercury so exactly in its appearances, that it is not possible to distinguish by the eye a globule of the one metal from a globule of the other, when they are laid together. The fluidity of the potash metal, at the temperature of 60°, is considerably smaller than that of mercury; but at 100° its fluidity is perfect; at 50° it is malleable, and at 32° is chrystallized. It is an excellent conductor of electricity, and requires a red heat to distil it, that process not at all altering it. Its specific gravity is its most singular property. At 40° of Fahrenheit it swims in naphtha, the lightest of fluids; its specific gravity is to that of water as six to ten; it is, therefore, by much the lightest fluid in nature. When combined with an undue proportion of oxygen, it forms a grey substance, which, when fluid, is red brown. This is formed by fusing dry potash with the metallic base; and exposure to the air giving it the complement of oxygen, brings it all back again to the state of potash. When introduced into oxy-muriatic acid gas, it burns spontaneously with a bright flame, and makes muriate of potash. In hydrogen gas, with heat, it dise solves; the compound gas explodes upon exposure to common air, and deposits the metal on cooling. When thrown into wa ter at the common temperature, it instantaneously deflagrates; and a white ring of smoke frequently follows the flame, as in the combustion of phosphurets. When the water is in a close vessel, and there is no contact of air, the decomposition is equally rapid, but without light, and pure hydrogen gas is evolved. A globule, placed upon ice, burns with a bright flame, leaving a hole in it full of solution of potash. It discovers and decompounds the smallest portions of water, in alcohol and ether, even when previously purified with the greatest care. In sulphuric acid, it ra pidly seizes upon the oxygen, leaving sulphur half oxydated, and sulphate of potash. In nitrous acid, it forms nitrate of potash, and evolves nitrous gas. With phosphorus and sulphur, it forms phosphurets and sulphurets, which, on exposure to the air, be come phosphats and sulphats. It amalgamates with mercury; and the amalgam being exposed to the air, potash is formed, and the mercury left pure. With other metals it unites also, and the compound being thrown into water, is speedily decomposed; potash and hydrogen being formed, and the metal precipitated. It decomposes the watery particles, or the air, which are found in oils long exposed, and precipitates a brown soap. It readily acts upon glass, forming an imperfect oxyde with the alkali, which, by degrees, is fully alkalized when exposed to the air.

In many of its essential properties, the basis of soda resembles the very singular metal which we have just now described. But it is considerably less fusible, and its specific gravity is greater. It melts at 120° of Fahrenheit, and is quite fluid at 180°. Its specific gravity is to that of water as nine to ten nearly. It decompounds air and water, but without any luminous appearance. It acts on the acids in the same way, but without any light, except on the nitrous acid. In other respects it exactly resembles the basis of potash.

Having detailed the properties of the two new metals, and their manner of combining with oxygen so as to form the fixed alkalis, the ingenious author proceeds to offer some general observations on what he terms the relations of those metals to other bodies; by which it turns out, that he only means to discuss the point of their classification and nomenclature. He firsts asks, whether they should be considered as metals or not? And having very properly determined this in the affirmative, notwithstanding their small specific gravity, which, as he observes, is not a sufficient reason for neglecting their various metallic properties, he names them Potasium and Sodium,-names, as he remarks himself, more significant than elegant; but we are greatly relieved at finding them no worse. A report had reached us, of Scdagen and Petagen having been propounded by high chemical authority. It was even hinted that Mr Tennant leaned towards such a nomenclature; and persons were not wanting who apprehended, that, in this courtly age, some terms might be introduced complimentary to the best of Sovereigns, and the purity of church establishments. We well knew no such thing was ever long listened to by the discoverer himself, whose political sentiments are as free and as manly as if he had never inhaled the atmosphere of the Royal Institution. But it was well to be relieved from all such alarms by the event; and having accidentally gotten upon a point, in which science is sometimes disgracefully blended with politics, let us make a step further to express our abhorrence of the spirit in which some sycophants have lately dared to profane the commonwealth of letters, by the introduction of courtly and national prejudices. It is understood, that the French Sovereign has, either by himself, or through the Institute, awarded a prize to Mr Davy for his wonderful discoveries; and some men have been time-serving enough to cry out against his accepting honours from the merciless foe, the usurper,' the enemy of civilized society, and we know not how many other names. We have always kept in the view of our readers, that the commonwealth of science is of no party, and of no nation. It is a pure republic; and it is always at peace. Its shades are disturbed neither by domestic

VOL. 12, No. 24.

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malice nor foreign levy. They resound with no cries of factions, or of public animosity. Falsehood is the only enemy their inhabitants ever pursue;-Truth, and her minister, Reason, the only leaders there followed; and they who would break the equality, or disturb the tranquillity of those sacred haunts, deserve to be chased out of civilized society, as aiming at the destruction of the only pure, dignified, innocent feature-the only remnant of the Divine origin-which bad passions have left in the character and conduct of men.

Having ascertained, that oxygen formed the common principle in the fixed alkalis, Mr Davy was disposed to question whether it did not also exist in ammonia, although no notice had been taken of it; and upon attending to the experiments of Berthollet and others, by which ammonia was decomposed, he saw no reason to conclude that oxygen might not exist there in a small proportion, and disappear, by forming water in the course of the process. He therefore commenced a series of experiments which speedily removed all doubt on this head. Having prepared a perfectly pure piece of charcoal, he ignited it in a small quantity of perfectly pure ammoniacal gas, by a galvanic battery; and a substance was collected on the sides of the tube, which effervesced with muriatic acid, and was probably carbonate of ammonia. Pure ammoniacal gas was then passed over ignited iron wire, in a platina tube; the gas being first passed through a refrigeratory, before touching the wire, and then through another refrigeratory, after it had gone over the wire, and before it reached the last receiver. No moisture was formed in the first refrigeratory; but a sensible quantity of water was deposited in the second. After passing and repassing the gas frequently over the wire, the wire had gained parts of a grain;ths of a grain of water were deposited; and 33.8 cubic inches of gas were expanded into 55.3, containing a mixture of hydrogen and nitrogen gases, in the proportion of 3.2 to 1. in volume. By other experiments on the decomposition of ammonia, in which some loss is always found after collecting the hydrogen and nitrogen gases, Mr Davy infers, that it contains about seven or eight per cent. of oxygen. This body may therefore, as he observes, be considered as the principle of alkalescence; with as much reason as the French have made it the principle of acidity.

4 4

This very valuable paper concludes with some general remarks and notices respecting the alkaline earths. Analogy would lead one naturally to suspect, that they are similar to the alkalis in their constitution. In the communication now before us, Mr Davy has only mentioned the results of some experiments which tend to verify this conjecture, in the cases of barytes and stron