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discusion of the phænomena of light, which have again ate tracted no inconfiderable share of attention.

IX. Experiments and Observations on the Light which is spontaneously emitted, with some Degree of Permanency, from various Bodies. By Nathaniel Hulme, M. D. F. R. S. and A. S.'

This is a pleasing and entertaining article, of which we Thall offer a short analysis. Dr. Hulme shows very clearlv, that the phosphorescence of putrescent animal substances is not, as has been supposed, in proportion to the degree of putrefacrion, but that, in reality, it ciriini.hes the farther they are advanced to that slate. This light, as many authors have lately endeavoured to prove, appears alío, from our author's experiinents, to be a constituent part of the animal, and capable of heing separated from it, and added to any other body, chieily Huid ones. Some substances have a power of extinguishing the light. These are,

"1. Water alone. 2. Water impregnated with quickline. 3. Water impregnated with carbonic acid gas. 4. Water impregnated with hepatic gas. 5. Fermented liquors. 6. Ardent spirits. 7. Mincral acids, both in a concentrated and diluted state.' 8. Vegetable acicis. 9. Fixed and volatile alkalis, when dissolved in water. 10. Neutral salts: viz. faturated solutions of Epsom salt, of common salt, and of fal ammoniac. 11. Infusions of chamomile Howers, of long pepper, and of camphor, inade with boiling-hot water, but not used till quite cool. 12. Pure boney, if used alone.' P.171.

The power of the neutral falts in preserving or extinguishing light, is peculiar. li depends on the proportion of salt, as if some solid pariicles were necessary to reflect the light, while too many obscured it. One drachm of Epsom salt, in an ounce of water, rendered the fluid luminous, when the light of fishes was added : feven drachms obscured it. We fay obou fcured, because the light was not loft ; for, when the solution was properly diluted, it was restored. Motion seems to render phosphorescence more vivid, but at no time is it attended with heai. Cold, at least so low as the freczing point, obscures the light, which is again restored by thawing; moderate heat, on the contrary, renders it more vivid; and, when light is col. lected in a luminous ring on the top of a phial, warming it ditfules the light in rays streaming downwards to the bottom, where it is apparently loft. Light is destroyed, without recovery, by more violene lieat; bụt the degree is not the same in differeni substances, or probably at different times: in general, die rilio from 969 to 130°, seems requisite for thie purpose.

The human body appears, at times, to annihilate the pho

sphorescence of bodies, at others to increase it; and this variety seems owing to the degree of heat of the body, and the time of application. The blood was rendered slightly luminous, but the light was of no long duration, and, when putrid, it appeared to be rejected with a repulsive force. The serum, probably as a saline fluid, was beautifully illuminated by herring-light. Milk was rendered luminous, but when four, the light was soon extinguished. Bile seemed scarcely capable of retaining the light. Phosphorescence, whether animal or vegetable, from rotten wood, appeared to be the same.

• X. Account of a Series of Experiments, undertaken with the View of decomposing the Muriatic Acid. By Mr. William Henry.'

The pretended discovery of the radical of the muriatic acid by Girtanner, and the refutation by Van Mons, must be fresh in our reader's recollection. Mr. Henry has been also unsuccessful, but without having made any pretensions to the difcovery. His modest - Account of his · Series of Experiments' demands our conimendation. He employed the mu. riatic acid in the form of gas, as its purest state, and used the ele&trical shock as the moft powerful agent. He found, however, hydrogenous gas, after the shocks had been received, and discovered that the muriatic acid air itill contained water, in the proportion of 1.4 tu 100 cubic inches, though it had stood on warm muriat of lime. This water furnilhed the hydrogen, while its oxygen united with the muriatic acid, and acted on the mercury, which confined the airs. The really acid portion of muriatic gas was unaffected. When the electric Thocks are passed through a mixture of carbonated hydrogen, and muriatic acid gases, their water is decomposed by the carbon of the foriner, and the result is carbonic acid and hydrogenous gases. The carbon, therefore, though powerfully attractive of oxvgen, could not separate it from the muriatic acid; fo that, if the latter be an oxygenated substance, no reagent yet known is powerful enough to destroy their union. Mr. Henry was equally unsuccessful in his analysis of fluoric acid.

XI. On a new fulminating Mercury. By Edward Howard, Esq. F. R. S.'

Mr. Howard's memoir is a very interesting one. The com. position of this powder we shall first notice.

• One hundred grains, or a greater proportional quantity, of quicksilver (not exceeding 500 grains) are to be dissolved, with heat, in a measured ounce and a half of nitric acid. This solution being poured cold upon two measured ounces of alcohol, previously introduced into any convenient glass vessel, a moderate heat is to be applied until an effervescence is excited. A white fume then be

gins to undulate on the surface of the liquor; and the powder will De gradually precipitated, upon the cessation of action and re-action, The precipitate is to be immediately collected on a filter, well wallied with distilled water, and carefully dried in a heat not much exceeding that of a water bath. The immediate edulcoration of the powder is naterial, because it is liable to the re-action of the nitric acid; and, whilft any of that acid adheres to it, it is very subject to the influence of light. Let it also be cautiously remembered, that the mercurial solution is to be poured upon the alcohol.' P. 214. 'This powder fulminates on concussion by the electrical Mock, and by a spark froin flint and steel. Jis power is more than double that of gunpowder, but its influence is not so extensive. Four grains of gas only are separated, which cannot account for the force of the explosion, so that probably some of the mercury is reduced, and scattered in vapour. The gas was a mixture of carbonic acid and nitrogen gafes,

The principal re-agents which decompolc this gas, are the nitric, thic niuriatic, and the sulphuric acids, the last of which occafions an explosion, if concentiatcil, at the moinent of contact. ; • Upon the whole, I trust it will be thought reasonable to con. clude, that the mercurial powder is composed of the nitrous ether, ized gas, and of oxalate of mercury with excess of oxygen.

ont, because the nitric acid converts the mercurial powder enzirely into vitrous gas, carbonic acidi gas, acetous acid, and nitrate of mercury.

• 2dly, Because the dilute sulphuric acid resolves it into an unjofiammable oxalate of mercury, and separates from it a gas relem. bling that into which the fame acid resolves the nitrous etherized

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• zdly, Because an uninflammable oxalate is like wife left, after the muriatic acid has converted a part of it into sublimate.

qihly, Because it cannot be formed by boiling nitrate of mercury in dulcified spirit of nitre; although a very inflammable oxaa laie is by this means produced. ... sihly, Because the difference of the product of gas, from the fame measures of alcohol and nitrous acid, with and without mer. cury in solution, is not trifling; and,

.6thly, Because nitrogen gas was generated during its combus tion in the glass globe.

• Should my conclusions be thought warranted by the reasons I have adduced, the theory of the combustion of the mercurial pow. der will be obvious to every chemiit. The hydrogen of the oxalic acid, and of the etherized gas, is first united to the oxygen of the oxalate, forming water; the carbon is faturated with oxygen, forming carbonic acid gas; and a part, if not the whole, of the nitrogen

of the etherized gas, is separated in the state of nitrogen gas; both which last gases, it may be recollected, were after the explofion present in the glass globe. The mercury is revived, and, I prelune, thrown into vapour; as may well be imaginel, from the immense quantity of caloric extricated, by adding concentrate rulphuric acid to the miercurial powder.' P. 222.

The proportions seem to be of pure oxalic acid about .21 ; of mercury nearly .65; and of nitrous etherized gas and excess of oxygen .14. This powder takes fire at the temperature of 368° of Fahrenheit, and will explode in vacuo. It seeins, from experiment, not likely to be useful in grenades from its limited sphere of action, but may probably be of ferrice in destroying cannon.

The meteorological journal for 1799, as usual, concludes the volume. The mean height of the out-door thermomejer was 48° 5, of Six's 47o.9, of the barometer 29.84; and the quantity of rain only 19.66 inches. The mean heat of April was 44° nearly. The year was undoubtedly very cold. The therinometer was never above 77° in June and July, and this only in the morning, when it is evidently influenced by the reflected fun. On the afternoon of these days it was only 67o.

An Introduction to Harmony. By William Shield. 480. 188.

Boards. Robintons. 1800.

FROM the acknowledged professional talents and expe. rience of the author, this work has been for some time iinpatiently expected by musical professors ; nor do we believe that expectation of useful information on the art and practice of music will be disappointed.

The two principal contiderations which Thould necessarily occupy the mind of the critical examiner of a work like the prefent are, first, the importance of the lubject; and secondly, how far the author has fulfilled the promiles made in his proporals or title-page.

Mr. Shield modestly calls his work an Introduction to Harmony,' which is frequency another phrase for preface ; and the import of which, in its most legitimate sense, can no more imply a complete system, theory, or ireatise, on mufic, than the vestibule of a building or the avenue to it can be the representative of the whole structure; and, for the importance of what is promised (to continue the parallel) as the avenue to a beautiful building is generally planted in such a manner as hull best delight the eye of those who approach it, so our ingenious author has prefented to the view of his reader, the most prominent and alluring features of his art, concealing deformities,

whether of situation, petty offices, or old buildings ; and early in his work, quitting grammatical and elementary dryness, he has plunged at once into the elegance and refineinents of the great masters, whose genius and science have extended the limits, and embellished the whole circumference of music.

Taking it for granted, we suppose, that the reader has not the horn book or gamut to learn, the author has not given a general scale of mulical sounds, from the two extremes of high and low, that are used in compofition for different voices and instruments. What he terms the scale, is only a few fteps of the musical ladder : eight notes ascending and descending, from Coc.

Nor have we a time-table, or any rule given for measuring the duration of the notes and rests which he uses ; though, in the first part of his work, every species of note is employed, except the demisemiquaver. But as this tract is only styled an introduction to harmony, not melody, which depends on mcafure and accent, the author perhaps forgot the time-table, or thoughi it unvecessary in the discussion of harmony. Yet if the reader of this ingenious publication should not be well acquainted with the aliquot parts of a semibreve, the inany excellent examples of compostion interspersed through the work in illustration of its rules, would afford him liktie pleasure or profit in solitary study.

After the short account of the scale, and the intervals contained in the natural octave, Mr. Shield proceeds immediately to the common chord major of , and its products of 6th and 6.

We have next the scale and common chord minor, with its inverfions.

After this we have a clear account of the high crime and misdemeanor of two fifths and tuo cighths, with the methods of avoiding thein.

We are glad Mr. Shield prefers calling the sharp 7th of a key the leading note, rather than the sensible note. Though note sensible is very elegant and expressive in French, it does not naturalife well in English. Sensible is a term equivocal in our tongue, and generally applied to the mind, when operated upon by the senses. We cannot say that a note is fenfible without personifying it. A fenfitive plant is supposed to have feeling from its thrinking at the touch; but this cannot be faid of a note; which may excite sensation and feeling in the hearer, but not poffefs either felf. The sharp 7th is a piquant stimulating found, which awakens attention and interest in the hearer more than any other discord; and, if leading note thould not fufe

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