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to contemplate, without fear, the variety and grandeur of the objects which compose the science of nature. What, then, would he have thought of the man who risques his life a thousand times to extend the limits of that science? You have proved to me, that even in this world we may con. ceive sensations which we have never experienced, talte en joyments which seem to belong to a different species, and collect ideas and images of which our universe has never offered to us the first germ or the first outline. Pardon me for speaking so long of the accessories of your labour. You have anatomised the world; but it is a living, body which serves you as a study, and which you have taught us also to admire. Columbus did not expose himself to more dangers than you; but he carried to America the box of Pandora, and
you have brought from Mont-Blanc the most falutary plants. You have discovered, amidst the chaos, the mark of the divine hand which created the universe.
You have elevated my foul, in making me fee these magam zines of the world, and I perpetually lament my weakness, which will not permit me to follow your steps. But my imagination frequently fupplies my want of power. In perufing your productions, I hear the deep crash of the avalanches, and the crackling of the electric matter. Filled with terror and admiration, I sometimes perceive the tomb of a rash hunter; I see his fpirit wander peaceably in these solitary places, and I feel that I envy him. It seems to me, that I would willingly finish my days with M. Necker in these delightful retreats, to render there a last homage to nature and to conjugal love, which alone remain to us amidst the wreck of all the illusions of life. He has entrusted me with the charge of describing to you what we have both felt; we have, while we have admired your courage, together trembled at your danger; and, reflecting on the ties which attach us to you, we believe we have a right to recommend to you the care of a life which is very dear to us.'
From the extracts which we have offered, the nature of these Neckeriana, as they may be called, may be judged. Madame Necker appreciates the merit of her literary friends more highly than other perfons have done; but this is not unpleasant; it is the involuntary exaggeration of friendfhip, and we readily pardon it.
APP. VOL. XXIV. New ARR.
Annales de Chymie, Vol. XII. XIII. XIV. (Continued from Vol. XXII. New Arrangement, p. 523.)
Annals of Chemistry. IN the twelfth yolume of these annals, we meet with a menoir, by the abbé Hauy, on fonte varieties of the fulphata of barytes, or heavy spar; but ari abstract' of it would be unintelligible without a diagram. M. Giobert communicates a process for preparing Kunckel's phosphorus from urine, more cafy and æconomical than that employed by Schecle and Ghan with the bones of animals. "There minute details are not adapted to our journal. The method is undoubtedly fimple, and consists in combining the phosphoric acid with lead, by adding a folution of lead in the nitric acid. ** An explanation of M.Coulomb's seventh Memoiron Magnetism, by the abbé Hauy, follows. It is difficult to give à just idea of the author's attempt in shorter words than those which tħe abbé employs; and we should have examined tist whole in a separate article, if, after mature reflection, we had not feen grcat reafon to question M. Coulomb's original drypothesis. If this should not be establishcd, the whole system will fall, and the experiments will be useless. He fupposes two fluids confined in the fame needle, the molecules of which attract and repel each other in the inverse proportion of the square of the distance. While the needle fhows no signs of magnetism, he imagines that thesc Auids neutralise each other; but, when it becomes magnetic, the neutral is decomposed, and each ingredient acts feparately. The whole is hypothetical, and is encumbered with too many tfeless, and some inconsistent suppor lions.
The most advantageous form of magnetic needles, in our áuthor's opinion, is that of two long triangles united at their base, called aiguilles en Aeche.
He also remarks;. that the fum 'of the forces of feparate, fimilar, and equal Heedles, is more than double that of the bundle wbich they
forni when united. The most efficacious method of conveying the magnetic virtue, is that of the double touch. Needles made of separate laminæ are very powerful. M. Coulomb exhibited one weighing 20 pounds, to which a. piece of soft iron adhered so strongly, as to require near 100 to separate it.
M. Cortinovis endeavours to prove that platina was, known to the ancients, and called electrum. The arguments are not stated; but they seem, from some circum.
stances, to depend on the pillars of electrum, mentioned by different authors. The meaning might be; that the pillars were encrusted with amber, or that they were composed of a yellow marble resembling it. M. de Rasumowski, in his observations on the formation of granites, supposes that, as they are evidently cryftallifed, they must have been dissolved in a more active menstruum than water, probably the sparry acid: but the idea is not supported by Fecent observations. M. Carminati gives an account of a root brought from Quito, called calagnala, which has been introduced into the Materia Medica of some authors. It is an astringent, chiefly gummy. It resembles in many respects, and perhaps in medical properties, the polypodiumi vulgare.
The ordinary fulphuric acid, it is observed, is often mixed with some of the nitric acid: this is discovered by immersing å straw, previously dipped in ammoniacal carbonate (common spirit of fal ammoniac), round which any nitric acid, that may be in the mixture, forms a white cloud. Any portion of the muriatic acid would produce the same éffects; but this is seldom found in cominon oil of vitriol.
The memoirs of the Italian society at Verona furnith two chemical articles. One is by M. Lorgná, who pretends that congelation not only purifies sea-water, but separates almost every kind of impurity from water. The congelation, we think, must be now, and often repeated. The fecond is by M. Fontana, who supposes, from his experiiments on the water of the marshes of Sienna, that Aints may be reduced to powder by the fulphureous acid, and thus suspended in water. He explains, in this way, the fuspension of the flint in the waters of Iceland, but the explanation is unsatisfactory and ill-founded.
The observations on the properties of muriat of tin, by M. Pelletier, form ä valuable article, highly interesting to artists. Muriat of tin is either the solution of the metal in the common acid, or in the oxygenated acid. Artists dissolve their tin in different ways, which they usually keep secret; sometimes in the pure acid, sometimes, as our author supposes, in the nitro-muriatic. We may remark that the oxygenated muriat of tin, if diluted with water, will diffolve more of the metal, and the solution is then reduced to the usual state. The muriat of tin, with the fulphureous acid, is precipitated of a red colour, which foon becomes, on heating, a bright and beautiful yellow, that promises to be. highly useful as a pigment. We cannot enter on the par ticular details, but may obfervé, in general, that the oxygenated muriat of tin furnishes an excellent steady mordant, at an easy rates that the muriat of tin attracts oxygen (
strongly, as to take it from inany acids and metallic oxyds, that the solution of gold affords no purple precipitate with the oxygenated muriat; and, lastly, that the common muriat absorbs oxygen from the atmosphere, and may consequently be employed to determine its proportion in any quantity of air.
M. Gadolin, of Abo, communicates the results of experiments on twenty fpecies of lichen, as materials for dye. ing, by M. Westring: many of them are 'natives of our own country, and their management is simple and easy.
A valuable essay by M. Vauquelin follows: it is entitled Chemical and Physiological Observations on the Respiration of Infects and Worms. The subjects of his experiments were, the gryllus viridiffimus, locufta vermivora, limax Alavus, and helix pomatia. He first describes the or gans of respiration, and proceeds to confider the effects which the respiration of caterpillars and snails on the air. He found that insects and worms respire oxygen like larger animals, with warm blood, and convert it, like them, into water and carbonic acid, that this air is essential to them; and that they die as soon as they are deprived of it. Snails, he says, have a considerable respiratory force; and their organs are not affected by carbonic acid or azote; but they extract all the oxygen which may be united with these airs, and do not die till the vital air is wholly exhausted.
Miscellaneous remarks on chemical subjects occur in a letter from M. Giobert: and the volume concludes with an account of some new chemical works.
The thirteenth volume commences with two memoirs by M. Haffenfratz, containing an explanation of some phænomena, which seem to contradict the laws of chemical affinity. These are followed by a description of an atmospheric eudiometer by M. Reboul. The substance employed by him to separate the vital air, and ascertain its proportion, is pliosphorus, when burning. This method, however, is in some respects uncertain.
M. Pelletier's analysis of what are called by manufacturers blue cinders, is not interesting to us, as they are sufficiently common in England: they contain neariy equal parts of carbonate of lime and carbonate of copper.
M. Vauquelin's experiments on the solubility of-common falt in folutions of different neutral salts, with the consequent phænomena, are curious. It is remarkable that a saturated solution of nitre should be able to dis. solve. common falt, and then take up more of the nitre, which it would reject before : yet so little are general rules infallible, that this experiment may frequently be made with success. It is also surprising that a solution of
Comie falts will dissolve a larger quantity of another neutral than distilled water alone. Sometimes, indeed, a little of the former salt is precipitated, but never without a separation of heat. Sca-lalt alfo, at the temperature of about 99, or 10° of Reaumur, is more foluble than any other alkaline or earthy neutral. It is not, however, equally soluble in higher temperatures; many neutrals will precipitate it from boiling water, while the sea-falt precipitates these neutrals from cold water. In the saltpetre refineries, common salt is separated during the boiling; yet, to make the nitre crys-, tallife in the cold, sea-falt is added. This phænoinenon is more striking and decisive with sulphat of soda. In general, those salts which require much water in crystallising, discharge a proportional quantity of heat in their diffolution, and of course absorb as much during their crystallisation. The quantity of heat thus absorbed, and let loose, fhould be determined with more precision. We shall add the results more comprehensively, as it is a subject little understood, even by experienced chemists.
The greater part of the faline solutions are decomposed by common salt, with the separation of a quantity of heat, in proportion to the falt precipitated. 2. Some solutions deposit more of their salt than they dissolve of common falt; and the latter occasionally produces no precipitation. - 3. Similar masses of different falts require different quantities of caloric for their solution; and they have not all an equal afhnity for water, at least at the temperature employed by M. Vauquelin. 4. The solutions are never wholly decomposed by common salt, though a little of it is always mixed with the salt precipitated the folution, in consequence, always becomes fpecifically heavier.
M. Pelletier's 4th and 5th memoirs on the union of phosphorus with metallic fubftances, offer nothing that we can select. Phosphorus, in the mineralisation of metals, acts nearly as arsenic does. It may also, it is faid, be united to metallic oxyds; but this point requires farther examination.
M. Reboul's description of the valley of the Gave, in the Bearnois district, is written with the clearness and intelligence which distinguish M. Sauffure's philofophical narratives. In general, it is obferved, that the vast chains of mountains in Europe, in Afia, and America, have val. leys parallel to them, which may be styled longitudinal.
I confess (says M. Reboul) that I have been unable to distinguish, in the country through which I have passed, any fraces of a longitudinal valley. That of the Gave, in the Bearnois, cuts the chain at right angles, where it is most