his epistolary efforts breathe more of the spirit and manner of Cowper, than any in our language. And if the general qualities of the letters intitle them to commendation, their specific object gives them a strong claim upon our gratitude. If a beloved friend pays the debt of nature before us, it is high consolation that no power of medicine was left untried. So, in the case of Cowper, it is no ordinary satisfaction that all the resources of kindness and Christian sympathy were exercised upon him, and that there was found a Levite who did not pass by on the other side.” The 21st letter to Miss ******* will be read with interest by all parents, and may be safely and profitably put into the hands of many children. The 14 letters to Dr. **** are (we apprehend) those alluded to by Mr. Cecil in his memoirs of Newton, and are very excellent. Some of the Miscellaneous Papers which follow, are in 'our author's best style. The 2nd, 3rd, 4th, 5th, that on dress, and the last, appear to us highly deserving of attention. Among the last series of papers in the volume, that which is intitled Thoughts on the Slave Trade, will not, by his own friends, or the friends of evangelical religion, be deemed the least valuable. The memoirs of his life, originally published by himself, in one respect naturally disappointed the expecta tion of the friends to religion and humanity. They certainly cannot be charged with touching too lightly his errors of conduct previous to conversion. It might have been expected, that in every confession of sin, and every supplication for pardon, the aid he had lent to the abominable traffic for human bodies on the shores of Africa, would have occupied a prominent place. But no such acknowledgement of guilt, no such expression of abhorrence, no such damnatory sentence ou the trade, was pronounced by him, as might have been anticipated in an awakened character. On the contrary, such is the influence of habit, that Mr. N. continued a Captain in the trade, for some time after his change. For this wrong to society, the essay, to which we have referred, endeavours to make reparation. If', says he, my testimony should not be necessary or serviceable, yet perhaps I am bound in conscience to take shame to myself, by a public confession, which, however sincere, comes too late to prevent or repair the misery and mischief to which I have formerly been accessary. I hope it will always be a subject of hu miliating reflection to me, that I was once an active instrument in a business at which my heart now shudders.' Vol. VI. p. 520. God be thanked! this rank offence, which smelled to heaven,' is now branded as infamous by the voice of the people in Parliament. He who now perpetrates it, must make war against his country, as well as his God, and the natives of Africa. That charter which heaven gave the Africans in common with the rest of mankind, but which the grinding spirit of commerce, and a ferocious tyranny, bad wrenched from them, is now restored to them, signed and sealed by the hand of a blushing and penitent pation. Woe be to that government, which shall lay its unhallowed hand upon the ark of universal freedom, which shall make us worse than slaves, by ordaining us to enslave others, which shall in any degree wink at the slightest violation of an act carried by the acclamation of a whole people! We here close our examination of this edition of the works of Mr. Newton. It is on the whole, we conceive, calculated to add to his reputation, literary and religious. The literary merit of the additional papers is considerable; and his religious system and reasonings are likely to rise in general esteem, by being thus contemplated as a whole. Some of his detached compositions might impress the general reader with an idea, that the author was somewhat rash and somewhat dogmatical: but when his works are thus examined in mass; when it is seen that any rash expression in one page has a counterbalance in another, that every position is furnished with its checks and guards; it will be acknowledged, that scarcely any six volumes in the language are likely to be read with more advantage than those before us. On a dying bed we should, we conceive, rejoice to have written them; and in the chair of criticism we feel it a high privilege, and solemn duty, to commend them to the perusal of our readers. Art. IIL Philosophical Transactions of the Royal Society of London, 1808. Part II. (Concluded from p. 519.) XXIII. ELECTRO-CHEMICAL Researches, on th. Decomposition of the Earths; with Observations on the Metals obtained from the alkaline Earths, and on the Amalgam procured from Ammonia. By Humphry Davy, Esq. Sec. R. S. M. R. I. A. Read June 30, 1808. Several of the pages of our recent numbers have been ọccupied with accounts of the brilliant discoveries of this most active and distinguished chemist. The flood of light he has already thrown over some hitherto dark regions of chemical theory, has given a new aspect to the whole science. Still greater advantage, we doubt not, will yet resuit from his future investigations; which will necessarily lead to consi derable modifications in the received theories, and which will ultimately, we trust, render British chemistry, like the philosophy of Newton, the wonder of ages and the glory of our country. In the paper now before us, Mr. Davy, with a laudable liberality and disinterestedness, brings forward the results. of his inquiries while yet imperfect, that other chemists as well as himself may pursue the same train of discovery. With this view, he relates the methods employed for decomposing the alkaline earths; his attempts to procure the metals of the alkaline earths, the properties of which he describes; his inquiries relative to the decomposition of alumine, silex, zircone, and glucine: he explains the production of an amalgam from ammonia, with its nature and properties; and lastly, he exhibits some considerations of general theory, connected. with the metallization of the alkalies and the earths. The results of Mr. Davy's experiments on potash and soda, afforded him the strongest hopes of being able to effect the decomposition both of the alkaline and common earths. But many difficulties occurred in prosecuting the inquiry. The only methods that proved successful, were those of operating upon the earths by electricity in some of their combinations, or of combining them, at the moment of their decomposi tion by electricity, in metallic alloys, so as to obtain evidences of their nature and properties. From various cir. cumstances which arose in the course of his investigations, it seemed probable to Mr. Davy, that though potassium may partially de-oxygenate the earths, yet its affinity for oxygen, at least at the temperature he employed, was not sufficient to effect their decomposition. He has found, in his researches upon potassium, that when a mixture of potash and the oxydes of mercury, tin, or lead, was electrified in the Voltaic circuit, the decomposition was very rapid, and an amalgam, or an alloy of potassium was obtained; the attraction between the common metals and the potassium apparently accelerating the separation of the oxygen. The idea that a similar kind of action might assist the decomposition of the alkaline earths, induced him to electrify mixtures of these bodies and the oxyde of tin, of iron, of lead, of silver, and of mercury; and these operations were far more satisfactory than any of the others. While engaged in these experiments, by which he detected a metallic substance in barytes, lime, strontites, and magnesia, Mr. Davy was informed that Professor Benzelius, in conjunction with Dr. Pontin, had succeeded in decomposing barytes and lime, by negatively electrifying mercury in contact with them; and that in this way they had obtained amalgams of the metals of those earths. Mr. Davy immediately repeated these operations with perfect success and, by combining the method of M. M. Benzelius and Pontin with his own, he considerably extended the results. Thus he found that the residuum of the amalgam of barytes appeared as a white metal in colour like silver; that it was fixed at all common temperatures, but became fluid before it attained red heat, and did not rise in vapour when heated to redness in a tube of plate glass, but produced a black mass, seeming to contain barytes and a fixed alkaline basis in the first degree of oxygenation. The metal thus obtained is called barium. The metal from stronthes, called strontium, sunk in sulphuric acid, and exhibited the same characters as barium, except in producing strontites by oxygenation. Calcium, the metal from lime, has the colour and lustre of silver; but on the admission of air the metal instantly took fire, and burnt with an intense white light into quick-lime. Magnium, the metal from magnesia, appeared as a solid having the same whiteness and lustre as the other metals of the earths, and quickly changes to a white powder, which is magnesia. The term magnum is appropriated to this metal, because magnesium is already applied by Bergman and others to metallic manganese. Mr. Davy did not arrive at conclusions equally satisfactory, in his inquiries relative to the decomposition of alumine, silex, zircone, and glucine. He has however described various series of experiments: from the general tenor of their results, and the comparison between the different series, there seems great reason to conclude that alumine, zircone, glucine, and silex, are, like the alkaline earths, metallic oxydes. Yet the evidences of decomposition and composition are not of the same strict nature, as those that belong to the fixed alkalies and alkaline earths: for it is possible, as Mr. Davy remarks, that, in the experiments in which the silex, alumine, and zircone appeared to separate during the oxydation of potassium and sodium, their bases might not actually have been in combination with them, but the earths themselves, in union with the metals of the alkalies, or in mere mechanical mixture. And out of an immense number of experiments which he made, but very few gave distinct indications of the production of any earthy matter. M. M. Benzelius and Pontin found that mercury negatively electrified in contact with solution of ammonia, expands to four or five times its former dimensions, and becomes a soft solid which reproduces ammonia and quicksilver when exposed to air or water, evolving hydrogen in the latter fluid. On repeating this important experiment, Professor Davy found that a considerable time was required to form an amalgam with In 50 or 60 grains of quicksilver, in contact with a saturated solution of ammonia; and this amalgam became greatly changed even in the time required for removing it from the solution. This amalgam at 70° or 80" of Fahrenheit, is a soft solid, of the consistence of butter; at about 32° it becomes firmer, exhibiting itself indeed as a crystallized mass. Its specific gravity is not quite three times that of water. the ar it acquires a crust of ammonia. In water it produces a quantity of hydrogen, equal to about half its bulk, the water becoming a weak solution of ammonia. In muriatic acid gas, there is formed muriate of ammonia, a small quantity of hydrogen being disengaged. The quantity of basis of ammonia combined in 60 grains of quicksilver, does not exceed part of a grain; and to supply oxygen to this scarcely part of a grain of water is required. The experiments farther furnished a strict proof that ammonia is an oxyde with a binary base. Several other curious properties of the amalgam obtained from ammonia are detailed by Mr. Davy, but we have not room to recite more than the following: Mercury by combination with about zoo part of its weight of new matter is rendered a solid, yet has its specific gravity diminished from 13.5 to less than 3, and retains all its metallic characters; its colour, lustre, opacity, and conducting powers remaining unimpaired. This property of amino. nium leads Mr. Davy to his considerations of general theory, from which we shall quote a passage or two, and conclude, The general facts of the combustion, and of the action of these new combustible substances upon water, are certainly most easily explained on the hypothesis of Lavoisier; and the only good arguments in favour of a common principle of inflammability, flow from some of the novel analogies in electrochemical science. Assuming the existence of hydrogene in the amalgam of ammonium, its presence in one metallic compound evidently leads to the suspicion of its combination in others. And in the electrical powers of the different species of matter, there are circumstances which extend the idea to combustible substances in general. Oxygene is the only body which can be supposed to be elementary, attracted by the positive surface in the elec trical circuit, and all compound bodies, the nature of which is known, that are attracted by this surface, contain a considerable proportion of oxygene. Hydrogene is the only matter attracted by the negative surface, which can be considered as acting the opposite part to oxygene; may not then the different inflammable bodies, supposed to be simple, contain this as a common element? Should future experiments prove the truth of this hypothesis, still the alkalies, the earths, and the metallic oxides will belong to the same class of bodies. From platina to potassium there is a regular order of grada. tion as to their physical and chemical properties, and this would probably extend to ammonium, could it be obtained in the fixed form.' p. 363. • Whatever new lights new discoveries may throw upon this subject, |