times, it is true, melts us into softness, by gleams of human sensibility struggling through the stern and lofty abstractions which he so powerfully pourtrays; and their effect is the stronger, as they seem to bring back the metaphysical monster to the feelings from which he has estranged himself, and to ally him once more to our sympathies. But the feelings, the tenderness of Hamlet, are never out of sight; his human affections never quit him; and this child of morbidly acute, but natural sensibility, is much more truly, fully, and pleasingly represented by Mr Young. We confess we never saw any other Hamlet for and with whom we felt so strongly; for whose weaknesses we cherished such unmixed pity; whose sufferings we wept over so frequently, and whose death we lamented with grief so like the grief of brotherly affection. But Mr Young is an artist of a high class, and to true genius in his art, he adds an unremitting energy of exertion, and a success ful activity of study, which must raise him to the summit of his profession. The season, after a short interme. diate vacation or two, finally closed with one of those gross violations of good taste, which Mr Siddons, as provider of the public entertainments, must, in compliance with the general taste of the times, however repugnant to his own feelings and understanding, sometimes be forced to commit; we mean the equestrian exhibitions, by which our dramatic theatres have lately been degraded. We believe, however, that in the London houses they did keep the subordinate situation of an appendage to the play, but here they entirely usurped its place; and the Russian Impostor, Oscar and Malvina, and Timour the Tartar, were exalted into dramas, for the purpose of introducing the stable and its inhabitants, human and brutal, before a wondering audience. Were this rage general, Dibdin's Highmettled Racer would be an excellent subject to dramatize, and make a kind of equestrian domestic tragedy; while the Epping Hunt and the Whip Club might put to shame the rattling comedies of Morton and Reynolds. We must, however, do Edinburgh the justice to say, that it did not encourage these "new grand equestrian melo-dramatic spectacles," "these dreadful combats with real horses," and Mr Davis's "wonderful war-horse riding, breathing flames, and enveloped in fire!!!" but treated them with the neglect which such misplaced exhibitions should always meet with. Before closing this article, we must not omit to notice the complete refor. mation which has taken place in that department of the theatre of which we censured the conduct somewhat severely at the conclusion of our last year's record; but if our censure was then severe, it is but just that our praise should this year be proportionably high. The orchestra of our theatre may now be deemed one of its principal sources of enjoyment. The various parts are fitted with the utmost propriety and liberality; and the superiority of the taste and skill of the leader, Mr W. Penson, is made manifest, by the excellence and variety of the music which he selects, and the style in which he executes and conducts the performance of it. On this point we therefore feel not merely satisfied, but greatly delighted; nor is there indeed any circumstance in the general conduct and management of the theatre, but what demands, and receives, our most decided approbation. REVIEW OF SCIENCE. THOUGH the discoveries and improvements in science which we have to notice in our present volume, are inferior in some respects to those which occupied our attention in that of last year, still they are of considerable importance, and do honour both to the sagacity and the industry of those philosophers, who have not been deterred by the badness of the times from devoting their attention to the improvement of the sciences. In our last volume, we confined ourselves chiefly to the scientific discoveries made in Great Britain; but in this, in order in some measure to balance accounts, we shall take a pretty ac curate view of the recent labours of men of science on the continent; not neglecting, however, the improvements which may have been made in our own country. Our topics will be various, and by no means closely connected with each other. But that is the unavoidable consequence of the nature of our subject. We shall begin with chemistry, the science which at present is making the greatest progress, and which, on that account, is the most interesting. I. CHEMISTRY. 1. In our last vo ume we gave an account of Mr Davy's great discovery of the decomposition of the fixed alkalies, and of the properties of the very singular metallic bodies which constitute their bases. Since the publication of Mr Davy's papers, a very laborious set of experiments have been made upon the subject by Thenard and Gay Lussac. These experiments seem to have been undertaken at the suggestion of Buonaparte, who took it ill that the French chemists should be eclipsed by the discoveries of the British philosophers. He furnished the money requisite for the appara tus, and is even said to have schooled Thenard and Gay Lussac upon the subject of their experiments. This, in some measure, accounts for the style in which their book upon the subject, entitled Recherches PhysicoChimiques, has been drawn up. A pompous list of their own discoveries is held up to view, and they are at great pains to point out their superiority over Mr Davy in a number of minute particulars, of very little con sequence, and respecting which the original discoverer was very likely to give results not altogether correct. Their work, however, contains many very important particulars; and we shall deduce from it a more accurate account of the properties of potassi um and sodium, than we gave in our last volume. Potassium, obtained by heating iron-turnings and potash in a coated gun-barrel, (a process discovered by Thenard and Gay Lussac,) is a solid metallic body, having the brilliancy and the colour of silver; but speedily tarnishing and changing into potash when exposed to the open air. At the temperature of 60° Fahrenheit, its specific gravity is 0.865. It melts when heated to the temperature of 136°. The potassium examined by Davy, which fused at a much lower temperature, contained a mixture of sodium. Sodium may be obtained by the same process as potassium; but it is more difficult to succeed. In colour it resembles lead; at the temperature of 60° its specific gravity is 0.9722. It melts when heated to the tempe rature of 194°. Potassium and sodium unite with each other in any proportion, and form alloys always more fusible than sodium, and sometimes even more so than potassium. Three parts of sodium and one part of potassium form an alloy which remains fluid at 32°; but at -4° crystallizes into a brittle metal. By increasing the proportion of sodium, the alloy becomes less and less fusible; though it al ways continues more fusible than pure sodium, and its colour likewise approaches to that of silver. By increasing the proportion of potassium, the alloy becomes more and more fusible, and retains that property till the proportion of potassium is very great. An alloy of thirty parts of potassium and one of sodium, melts at a tempe. rature between 53° and 64°4. Potassium and sodium are capable of combining with three different proportions of oxygen, and of forming three different oxides, which deserve to be particularly described. The protoxide of potassium may be obtained by keeping the metal for some time in a small phial, the mouth of which is stopped with a cork stopper. It derives its oxygen partly from the air in the phial, and partly from the water which that air contains; both of which are continually and slowly re newed through the pores of the cork. The protoxide of potassium is bluish grey, very brittle, and so combustible, that it often takes fire of its own ac cord on simple exposure to the air. It generally takes fire, when put into oxygen gas, at the temperature of between 70° and 80°. It decomposes water with great rapidity, and is converted into potash. The deutoxide of potassium is obtained by exposing the metal to the action of water. This oxide is the well-known substance called potash, which need not be described here. The peroxide, or third oxide of potassium, was discovered by Thenard and Gay Lussac; and it is the greatest discovery which they made upon the subject. It had been observed indeed by Mr Davy, but he considered it as a protoxide, and under that title we described it in our last volume. It may be formed by burning potassium in oxygen gas. The oxygen which it absorbs, seems to be about doubl the quantity which is requi site to convert potassium into potash, *This is heavier than Mr Davy found it. But he determined its specific gravity when in a state of fusion, when it must be considerably lighter than at the temperature of 60°, The peroxide of potassium is yellow. Heat melts it, but with more difficulty than potash, and it crystallizes in plates on cooling. When thrown into water, a violent effervescence takes place, the excess of oxygen is emitted, and the oxide is changed into potash. When heated along with combustible substances, it is decomposed, and the combustible is very frequently set on fire. This happens with phosphorus, sulphur, charcoal, potassium, tin, antimony, arsenic, zinc, and copper. Sometimes the combustible unites with the excess of oxygen of the peroxide, without occasioning any combustion. This is the case with bismuth, lead, iron, and hydrogen gas. The peroxide of potassium is decomposed also when heated in contact with ammonia, muriatic acid, carbonic acid, sulphurous acid, and nitrous oxide. Sodium forms three oxides as well as potassium. They possess similar properties, and may be obtained in the same manner as the oxides of potassium. From the most exact experiments hitherto made, the composition of the oxides of potassium is as follows:— Potass. Oxygen. 100+10.25 protoxide. 100+ 20.50 deutoxide or potash. 100 + 41.00 peroxide. ་ The composition of the oxides of sodium is as follows: Sodium. Oxygen. 100+ 17.3 protoxide, The rate at which the oxygen increases in these oxides is worthy of remark. If we represent the quantity of oxygen which unites with 100 parts of potassium to form the protoxide by a, then the quantity necessary for the deutoxide is 2a, and the quantity for the peroxide 4 a. But the numbers which represent the quantities of oxygen necessary to constitute the respective oxides of sodium, are 4, 2a, 3a. If we represent the weight of an atom of oxygen by 7.5, then the weight of an atom of potas sium will be 73, and that of an atom of sodium 43.3. The oxides of potassium and sodium are composed as follows, (supposing o to denote an atom of oxygen, and p and s an atom of potassium and sodium respective, ly :) Oxides of potassium. Protoxide, 1p+10 Deutoxide, Peroxide, According to Thenard and Gay Lussac, the proportion of oxygen in potash is 19.94; according to Davy, 163. The proportion in the text is that of Berzelius, which we consider as the most accurate. by Davy to ascertain whether oxymuriatic acid contained oxygen; the failure of all the supposed proofs of the existence of oxygen in that body; and the inference which that sagacious experimenter drew, namely, that oxymuriatic acid is a simple substance, and that muriatic acid is a compound of that body and hydrogen, nearly in equal bulks, supposing both constituents in the gaseous state. This was the opinion which had been entertained by Scheele, the original discoverer of oxymuriatic acid, and which was conceived to have been overturned by the experiments of Berthollet in 1785. Davy, in consequence of adopting this theory, found it necessary to change the name of oxymuriatic acid. He invented for it the term chlorine, in consequence of its green colour; and this is the name by which we shall henceforth distinguish it. Chlorine, like oxygen, is a supporter of combustion; and, like oxygen, it has the property of combining with the greater number of the sim ple bodies. With some it unites only in one proportion; with others in two; while with some, charcoal for example, it does not combine at all. Such is a sketch of the theory of Davy, which was attended with some difficulties when originally proposed. But these difficulties have been gradually removed by the subsequent experiments of Davy and his brother. In this country, Davy's theory of the nature of chlorine and muriatic acid has been opposed by Mr Dalton and Mr Murray. All our other chemical philosophers have acceded to it, or at least have not openly opposed it. Mr Dalton's opposition is founded entirely upon hypothetical grounds, and will probably be laid aside upon more careful examination. He had formed an opinion that muriatic acid is a compound of 1 atom of hydrogen, and 3 atoms of oxygen; and chlorine, of 1 atom of hydrogen, and 4 of oxygen. Davy's theory clashed with this hypothesis, which was a favourite with Mr Dalton, and induced him to reject the theory altogether. Mr Murray's opposition was found. ed upon different principles. He endeavoured by direct experiment to demonstrate the existence of oxygen as a constituent of chlorine. His experiments were objected to by Mr John Davy. A controversy took place between these two gentlemen, which was carried on with considerable keenness on both sides. The su periority, in point of style and per spicuity, was on the side of Mr Mur ray; but in point of accuracy and experimental ingenuity, it was on the side of Mr John Davy. Mr Murray made a mixture of carbonic oxide, hydrogen, and chloric gas, and fired it by electricity. He obtained a quan. tity of carbonic acid gas; the oxygen in this gas he conceived to be derived from the chloric gas, and hence inferred that it existed as a constituent of that gas. These and some other cir cumstances, which appeared at first sight of difficult explanation, and scarcely reconcileable to Davy's theory, were obviated by the discovery of two new gases, made by Messrs Davy during the course of their experiments. Of these two gases we shall now endeavour to give an account. |