and next macerated for some time in dilute muriatic acid, which dissolves the oxides of cobalt and zinc, with a small portion of the peroxide of uranium. Pure protoxide of uranium remains undissolved. If the muriatic solution be precipitated with caustic ammonia in excess, we obtain oxide of uranium combined with oxides of cobalt and zinc. From 385 parts of pechblende treated in this way, Mr. Arfwedson obtained 25 parts of protoxide of uranium, being 15 parts less than the quantity stated by Klaproth. Mr. Arfwedson then describes the experiments he employed to reduce the oxide to the metallic state, and to determine its proportions, from which he infers that 100 parts of protoxide are composed of 96.443 of uranium and 3.557 of oxygen. He afterwards describes a number of experiments he made on some of the combinations of this metal, and their results, which are not interesting enough for us transcribe.

Art. V. is by the same author, and is "An Examination of the Oxidum-Manganoso-Marganicum, a hitherto unknown chemical Compound of the Protoxide and Deutoxide of Manganese." We are afraid that the influence which the alchymists formerly exercised over science is not yet wholly extinct; at least we know no other way but supposing this to be the case, of accounting for the great passion we observe at present among Chemists, particularly among the continental Chemists, to make new artificial compound substances, and to devote a large portion of time to their rigid examination. We do not say such pursuits are wholly useless, but we would warn our readers against employing much of their time in them, unless they have a pretty strong presumption that the compounds may be of some use in the arts, or may serve to illustrate the science. The latter effect may be the consequence of Mr. Arfwedson's researches, and, as such, we may hereafter perhaps give an outline of them, but must now pass them by with this slight notice.

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Art. VI. is an "Account of a New Mineral," which the author of the Paper, a Mr. Levy, proposes to call Babingtonite; and of which Mr. Children, in Art. VII., describes the examination by the blow-pipe, and shows it to contain, but in what proportions is not mentioned, silica, iron, manganese, and lime, and probably a small proportion of titanium. Art, VIII. is Astronomical Observations, by Colonel Beaufoy, which, in this instance, are of not much importance. Art. IX. is a good collection of the mean results of several meteorological tables kept at different places, and terminated by the following observations:-The mean annual barometrical pressure of 1823, notwithstanding the amount of rain and snow which fell being nearly unprecedented, and which for the last three years has been rapidly increasing, was greater than for many years past. The mean annual temperature shows that wet summers are generally cold ones; and the average of the year is 23 degrees below ordinary years. The winds in 1823 were of the same description as those of 1822.

Art. X. is" On the Effect of mitting the Electrical through Fluids," by Mr. C. Woodward. This Paper details

A CURIOUS ELECTRICAL EXPERIMENT, Which we shall give, omitting Mr. Woodward's explanation, that our readers may have a greater opportunity to exert their own talents. "Place," says Mr. Woodward, “a piece of glass on the table of the universal discharger, and bring the pointed wires nearly in contact upon the surface of the glass; over the intersection formed by the wire strew some gunpowder, and pass through it the charge of a jar concontaining about a square foot of coated surface, when it will be found that the powder will be invariably dispersed without inflammation.

"Take a glass tube, six or eight inches long and about a qual quarter of an inch in diameter, fill it

with water, and insert a cork at each end; through the corks pass pieces of wire, so as to form a conducting communication with the water; place some loose gunpowder on the glass of the universal discharger, as before; insulate the tube, and let it form part of the circuit; pass the charge through the water, and the gunpowder will be inflamed. I then," says Mr. Woodward, "pasted on a board, about three feet long, a narrow slip of tin-foil, in which, at equal distances, four intersections, of about one eighth of an inch, were made. I insulated the board, and placed over one of the intersections some loose gunpowder, and over each of the others, six or seven wafers. On transmitting in the common way a charge through the tin-foil, the powder was scattered, and the wafers blown three or four feet from the board, but on repeating the experiment with a tube of water, the powder was inflamed, and the wafers remained without Mr. any perceptible motion." Woodward then states, that he found the powder was inflamed in proportion as the tube was filled with a substance which was not a good conductor. Thus, if filled with ether or alcohol, the powder was set on fire; if filled with sulphuric acid, which is a better conductor, the powder will be blown away, and scattered without catching fire. "But the most remarkable circumstance attending these phenomena is, that it is immaterial whether the tube form part of the circuit before the electrical fluid passes through the gunpowder or afterwards. If the tube be placed on what I will call the negative side of the powder, for the sake of distinction, either in immediate contact with the coating of the jar, or in any part of an interval in twenty yards of chain, the powder will be invariably inflamed when the charge is passed."

has any interest for us. Art. XIII. is an analysis of the salts, the crystals of which are described in Art. XII. Art. XIV. is " On a Submarine Forest in the Frith of Tay," &c., and has been transferred to the pages of the Annals from the Transactions of the Royal Society of Edinburgh. We shall hereafter imitate the Annals, and take a part of this interesting paper into our own pages. The remainder of the Annals is taken up with Analyses of Books and Proceedings of Philosophical Societies.

TECHNICAL REPOSITORY FOR APRIL 1824.

WE intended to add here an analysis of the contents of this work; but on examining it attentively, we found nothing worth quoting; and to give the number and headings of the articles would be only copying the dullest part of a dull journal.

MANUFACTURE OF SHA

GREEN.

SHAGREEN is prepared only in the province of Astracan, by Tartars and Armenians.

Horse hides and ass hides are taken; but properly no more than the hinder back piece is useful to this purpose, which is cut off immediately above the tail, in nearly a semicircular form, about an arshine and a half above the crupper, and rather less than an arshine along the back. From long experience, the rest of the horse hide is found to be unfit for shagreen, and is thrown away. The back pieces thus cut out, are laid in a vat filled with clean water, and left in it several days successively, till they are thoroughly soaked, and the hair comes freely off. Then the hides are taken, one by one, out of the vat, spread against a board set slanting against the wall, one corner of the hide reaching over the edge of the board, where it is fastened; and in this position the hair is scraped off with a blunt scraper, and with the hair the upper pellicle, and the cleansed skin is laid again in clear water to soften. This done, they take it a second

time out, spread one piece after another in the manner described, scrape now the flesh side with the same scraping-iron, and the whole Iskin is cleaned again on the hair side with great care, so that nothing now remains of the softened skin but the clean fuzzy web which serves for parchment, consisting of thick fasciculi of mellow fibres, resembling a hog's bladder softened in water. After this preparation, the shagreen makers take in their hand certain frames, composed of a straight piece and a semicircular bow, and therefore nearly of the shape of the skin, which is stretched on it, with strings, as even and uniform as possible; and during this operation, it issprinkled between whiles with clean water, that no part of it may dry and occasion an unequal extension. In like manner, they finally wet them when all the stock of skins is stretched, and carry all the thoroughly wetted skins into the work-room. There the frames are, one by one, laid flat on the floor, so that the flesh side of the stretched skins is turned undermost. The other side is now thickly strewed over with the black, very smooth and hard seeds of a species of the herb goose-foot, or the greater orach, (chenopodium album) and which grows in great abundance, and almost to man's height, about the Southern Volga, in farm-yards and gardens; and that these may make a strong impression on the skin, a felt is spread over them, and the seeds trod in with the feet, by which means they are impressed deeply into the very yielding skins; then, without shaking off these seeds, the frames are carried again into the open air, and set leaning against a wall to dry, in such manner that the sides covered with the seeds face the walls, and cannot be shone on by the sun. In this situation the stretched skins must dry for several days successively in the sun, till no trace of moisture is perceptible in them, and they may be taken out of the frames. Then when the impressed seeds are beaten off from the hair side, it appears full of little pips and roughnesses, and has got that

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impression which the grain of the shagreen ought to produce, when the true polish has been given to the skin by art, and the dey now to be mentioned has been used previous to the straining. The polish is done on a stretching-bench, or a board on tressels furnished with a small iron hook, and covered with some thick felts, or flakes of sheep's wool, on which the dried shagreen may lie soft. This is hung in the middle by a hole, which has been occasioned by a string in the stretching, to the hook, and fastened at the end by a string, with a weight or a stone, by means whereof the skin is allowed to move to and fro, but cannot easily be shoved out of its proper situation. This done, the polishing or rasping is performed by two several instruments, the first being an iron crooked at one end like a hook, and sharpened; with this the surface of the shagreen is scraped pretty sharply, in order to remove the most prominent rugosities, which, from the horny hardness of the dried skin, is no easy matter, and in which great care must be taken, not to shave away too deeply the impressions of the orach seeds, of which there is imminent danger, if the iron be kept too sharp As the blade of this iron is very narrow, it will make the shagreen rather uneven, and therefore, after it the other scraper must be used; whereby the whole surface acquires a perfect equality, and only a slight impression remains of the seeds, exactly as it ought to be. After all these operations, the shagreen is laid again in water, partly for rendering it supple, and partly to make the elevations appear. The seeds having caused pits in the surface of the skin, the interstices of these having lost their prominent substance by polishing or shaving, and the points that were pressed down having lost nothing of their substance, now spring up above the shaved places, and thus form the grain of the shagreen. To this end the pieces of shagreen are left to soften 48 hours in water, and are floated several times afterwards

in a strong and hot ley, which it receives by boiling from an alkalescent saline earth (schora) found about Astracan. From this ley the skins are bundled warm on another, and thus suffered to lie some hours, whereby they swell up and are softened in an extraordinary manner." Again, they are left to lie 24 hours in a moderately strong brine of common salt, by which they are rendered fine and white, and excellently adapted to receive any agreeable colour, which the workman hastens to give them, as soon as they are come out of the pickle. The colour most commonly communicated to the fine shagreen is the sea green, as the most beautiful. But the expert shagreen makers have the art of making also black, red, blue, and even white shagreen. For the green dye, nothing more is necessary than fine copper filings and sal ammoniac. As much of the latter is melted in hot water as the water will dissolve. With this sal ammoniac water the shagreen skins, still moist from the brine, are brushed over on the ungrained flesh side, and when they are thoroughly wetted, a thick layer of copper filings is strewed over them, the skins doubled together, so that the strewed side lies inwards; then each being rolled apart in a little felt or locks of wool, they lay all these rolls orderly on one another, and press them equally by a considerable and uniformly pressing weight, under which they must lie 24 hours. In this time the sal ammoniac water dissolves enough of the cupreous particles for penetrating the skin with an agreeable sea green colour; and though it be not strong enough the first time, yet a second layer of copper dust, wetted with sal ammoniac water, with which the skins must lie again 24 hours, will be quite sufficient for staining them thoroughly, when they may be properly cleaned, laid out, and dried. For giving the blue colour to shagreen, they use only indigo, which, to this end, is not so prepared as for the silk and cotton dyers, but entirely without bones, only by a strenuous friction it is mingled and dissolved with the

other ingredients. They put about two pounds of finely grated indigo in the kettle, pour cold water on it, and stir it till the dye begins to dissolve. They next dissolve it in five pounds of pounded telakar, which is a sort of barilla, or raw soda salt, burnt by the Armenians of Kisliar, and a worse kind by the Kalmucks, adding two pounds of lime, and one pound of virgin honey, all thoroughly stirred, and set in the sun for several days, during which time the stirring is frequently repeated. The shagreen skins which are to be made blue, must be put only in the natron ley, (schora) but not in the brine made of common salt. They are again folded up wet, and sewed close together round the edges, with the flesh side turned inwards, and the shagreened hair side outwards, upon which they are three times dipped in succession in an old store dye-kettle, at every time pressing out the superfluous dye. Lastly, they are all brought into fresh dye, which must not be pressed out, and with which the skin is hung up in the shade to dry. They are for the last time cleaned, ornamented on the edges, and reduced to order. (To be continued.)

COAL TAR.

THE undermentioned substance may perhaps be worthy of the attention of some of our readers: other avocations prevent us at present doing more than inserting the letter.

To the Editor of The Chemist. March 29, 1824. SIR, There is a substance obtained on distilling coal tar, the properties of which have never, to my knowledge, been examined. It is called by the workmen employed in the gas works, "Fat," and by the generality of Chemists, "Naphthaline.' It is found in the neck of the retort. It is a brown substance, very much in appearance like the pyrolignite of lead of commerce, and of a very disagreeable smell. On subliming, it is found in the head of the alembic, in white, plate-shaped crystals, which are very inflammable. I should

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feel extremely obliged by your mentioning it in your useful little work, as it might induce some one to make experiments on it.

Yours, very respectfully,

A YOUNG CHEMIST.

A DISCOVERY OF SIR HUMPHREY DAVY DISPUTED. We are not at all disposed to think that the facts contained in the following letter, which we take from a valuable cotemporary Publication, at all diminish the merit of Sir Humphrey Davy. We even think they do not relate to the same mode of applying the tin, and we are certain, if they do, that the inventor could not at that period explain the modus operandi, so as to carry a conviction to the mind of every Chemist, that the proposed method would be effectual. galvanic agency, on which Sir Humphrey Davy's method is founded, though certainly discovered in 1791, was so little known for several years afterwards, that it is quite impossible Mr. Wyatt should have adopted his method from a knowledge of the phenomena of galvanism. Still the coincidence is striking, and serves to show that the most valuable discoveries may be blundered on by chance, and lost for want of a knowledge of their principles.

The

Sir Humphrey Davy's Remedy for the Decay of Copper Bottoms not original.

Skinner-street, March 29, 1824. GENTLEMEN, The following extract from an advertisement, inserted in a newspaper, entitled "The World," dated April 16, 1791, will, I trust, be thought worthy of a place in your valuable Magazine. While it confirms the efficacy of Sir Humphrey Davy's plan for preventing the corrosion of the copper sheathing of vessels, it shows, at the same time, that he had been anticipated in that discovery. The advertisement begins as follows-" By the king's patent, tinned copper sheets and pipes, manufactured and sold by Charles Wyatt, Birmingham, and at 19, Abchurch-lane, Londong" and after numerating the many advantages

which they possess, it goes on to say " they are particularly recommended for sheathing of ships, as possessing all the good properties of copper, with others obviously superior, which the following extract, from a report founded on actual experiment, by Dr. Higgins, clearly demonstrates, viz., that this coating of tin powerfully resists the action of salt-water, and by preventing the corrosion of the copper, operates as a preservative of the iron placed d contiguous to it.” The dimensions and weight per foot are then mentioned, and the various purposes to which the invention is applicable.

I am, Gentlemen, yours, &c. SAMUEL DEACON. Mechanic's Magazine.

INFLUENCE OF SOUND ON ANIMALS.

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IN the human ear the fibres of the circular tympanum radiate... from its centre to its circumference, and are of equal length; but Sir Everard Home has found, that in the elephant, where the tympanum.! is oval, they are of different lengths, like the radii from the focus of an ellipse. He is of opi nion, that the human ear is adapted for musical sounds, by the equality I of the radii; and that the long fibres in the ear of the elephant are the cause of its acuteness of hearing. A piana-forte having been sent on purpose to Exeter-change, the higher notes hardly attracted the notice of the elephant, but the low ones fixed his attention. The effect of the higher notes of the piano on the great lion at Exeterchange was only to excite his attention, which seemed very great. He remained silent and motionless; but no sooner were the flat notes sounded than he sprang up, attempted to break loose, lashed his tail, and seemed so furious and ‹enraged as to frighten the female spectators. This was attended with the deepest yells, which ceased with the music. Sir E. Home has found a similar inequality in the fibres of the tympanum in neat, cattle, horses, deer, hares, and cats. Phil. Trans. 1823.