with the extremities of the condenser wire, then repeat the above experiments, and the same results will be obtained. Finally, if the bars, being well cleaned, are changed from hand to hand, and the experiments again repeated, the same results will be produced. 658. But now, preserving the apparatus as it was, change the solution of potassa for very pure muriatic acid. The zinc bar, corresponding to the boreal pole, being first immersed in the acid, the austral pole will go eastward. Remove that bar from the acid which was last plunged in, and a little while after, the other bar, and without changing them at all in the hand, wait till the needle is quiet; commence by the bar corresponding to the boreal pole; at the moment when that which agrees with the austral pole shall touch the acid, the needle (the austral pole) will deviate towards the west, and it will go in the same direction as often as the experiment is repeated, whether the operation be begun on the right or on the left hand. 659. If the bars be then well washed and dried, and restored to the ends of the condenser wire they were in contact with before, but with that part which was before immersed, now in contact with the wire, and the immersions and experiment be repeated, one of these two things will happen: either the needle will constantly move to the east, whichever bar is first immersed, or the action will be very doubtful or null. 660. If, instead of turning the bars, they are changed one for the other, the needle will go constantly to the west, whichever bar is first immersed; but the previous results may be at any time restored by re-changing the bars, and then the needle will go to the east. 661. The faculty thus acquired by the bars of zinc, of becoming positive or negative, according as they are plunged either first or last in the acid, they preserve some time. They may be washed, dried, and held in the hand, without losing their state, and hence particular precautions are required in making delicate experi ments with the metals. 662. This faculty is not communicated either to the fluid or to the extremities of the condenser wire. All the metals which become magnetometers by muriatic acid, as well as all the acids which produce an electro-magnetic action with homogeneous metals, produce the same pheno mena. 663. These experiments may be compared, with interest, with the observations of M. Volta, that a band of wet paper, making part of the conductor of his pile, becomes charged with electricities, which it preserves some time; with that of M. Gautheret, who thought he remarked something similar in the conducting wires of the pile; and with that of M. Ritter on his secondary piles, the phenomena of which M. Volta attributed to the electro-motive action of the alkalies and salts interposed. A very decided electric charge may be remarked in the metals interposed between the conductor and the fluid; they are both unipolar, i. e. charged each with a single electricity, which they retain for some time, and this electricity is constantly positive in one, and negative in the other. They form, therefore, the elements of a species of pile, of which the extre mities may be detached without losing their electricity; and, in consequence of this property, I call it a secondary pile, with mobile unipolar extremities. 664. 'I have sometimes succeeded, with bars of some length, in obtaining distinct poles at each extremity, so that when the bars were turned, opposite results were presented by the needle; but I have not been able to discover the condition of this phenomenon, so as to be able to produce it at pleasure.' 665. M. Yelin remarks, however, that he has never yet been able to ascertain the existence of free magnetism, or electricity, in any of these bars. Many other experiments are given in tables, which we have not room to notice, though they are of great interest. The bars M. Yelin used were 275 of an inch in diameter, and 2:75 inches long.-Bib. Univ. xxiii. 38. TERRESTRIAL MAGNETISM. 666. The following curious electro-magnetic experiment was exhibited by Dr. Birkbeck, at the London Institution. A hollow globe of wood, fifteen inches in diameter, was first accurately turned, and, from the equator towards each extremity of its axis, grooves were cut parallel to the equator, at the distance of 41° from each other, like parallels of latitude, and another, rather deeper, groove from one pole to the other, along a meridian half-round. 667. Beginning now at the equator with the middle of a wire, about ninety feet in length, and one-tenth of an inch in diameter, which just fitted the grooves, it was carried round in the successive circles towards each pole, making an abrupt turn from one circle to another along the meridian groove above-mentioned. From the point where the wire arrived at the poles, it was carefully bound with silk, and returned back again to the equator along the same meridian. The two ends of the wire being thus brought together, they proceeded to a little distance from the globe, where they terminated. By this means the effect of the short abrupt turnings of the wire along the meridian towards the poles, is counteracted by wire returning back again from the poles to the equator, leaving thereby only the parallel wires active when the two extremities are connected with the battery. 668. The globe being thus far formed, it is covered with zones, in the usual way, so as to exhibit to appearance a common fifteen-inch terrestrial globe, the wire being completely hidden. But this covering is so laid on that, instead of the terrestrial pole coinciding with the poles formed by the wire, the latter is brought into lat. 75° N., and long. 76° 40′ W., which is the situation which Mr. Barlow conceives will best agree with the observed bearings of the needle in most parts of the world. Things being thus adjusted, the globe is placed on a large cup near the battery, so as to admit of its being placed in any position, or so as to bring any part to the zenith, without the encumbrance of the usual brazen meridian and horizon. A needle is now suspended over the globe, leaving it free to take any dip; while, by means of a silk suspension, it is also free to take any direction; lastly, the needle is insulated from the action of terrestrial magnetism, by opposing to it the north end of a small bar magnet in the line of the dip. By this means the needle retains its magnetic power, but is under no magnetic influence. 669. The extremities of the curves being now connected with the poles of the battery, the globe immediately becomes strongly active upon the needle, causing it to assume the same dip, and the same direction, with respect to the artificial globe, as the actual needle does in the corresponding part of the earth itself, at least to a very considerable extent. Thus, if we bring the Island of Ascension to the zenith, the needle is found perfectly horizontal, with a slight westerly variation. If we bring London to the zenith, we find the dip about 70°, and 24° or 25° of westerly variation; if the globe is again shifted in position, so as to bring Cape Horn in the zenith, the dip is about 60° the contrary way, that is, with the south end below; and the variation about 30° easterly, and so on with various other places. 670. The purpose of this experiment is to show, that what we have hitherto considered as the magnetism of the earth, may be only modified electricity, and to illustrate, experimentally, the theory advanced by M. Ampère, who attributes all magnetic phenomena to electrical results. ROUSSEAU'S APPARATUS. 671. M. Rousseau, who has been occupied several years in the construction of dry Voltaic piles, has conceived the idea of employing those instruments to appreciate the different degrees of conducting power of the substances arranged in the class of bad conductors of electricity. For this purpose he has contrived the apparatus we are about to describe. The dry pile, which forms the principal part of it, is made of discs of zinc and tin-foil, separated by pieces of parchment, soaked in a mixture of equal parts of oil of poppies and essence of turpentine; the whole is covered laterally with resin, to prevent the contact of the air. The base of the pile communicates with the ground. Its upper extremity may be connected by a metallic wire with an insulated vertical pivot, carrying a weakly magnetic needle, balanced horizontally. On a level with the needle, and distant from the pivot, about half the length of the latter, is a metallic ball, also insulated, but communicating with the pile. It is evident that, by this arrangement, the electricity accumulated at the upper pole of the pile is communicated to the needle and the ball; and consequently repulsion ensues, tending to separate the needle, which is moveable, from the ball which is stationary. If we place the pivot and the ball in the magnetic meridian, the needle touches it, and remains at rest as long as the apparatus is not connected with the pile; but the instant the communication is established between them, the needle is repelled; and, after some oscillations, takes its position of equilibrium, depending on its magnetic power and the energy of the pile. These two quantities remain constant for a considerable time, with the same apparatus, as may be ascertained by determining the angle which the needle makes with the magnetic meridian, after it has assumed a fixed position, by means of a divided circle adapted to the cage which covers it. A s.mple conducting needle, suspended by a metallic wire of proper diameter and length, might be substituted for the magnetic one; but M. Rousseau's apparatus is much more convenient, and sufficiently sensible for the kind of effect which it is his object to measure. 672. To use it for ascertaining different degrees of conducting power, it is sufficient to place the substance submitted to experiment in the electrical current, taking care that the thickness which the electricity has to pass through be always equal. If the flow of the quantity of electricity necessary to produce the greatest deviation be not instantaneous, the time required by the needle to assume its fixed position may be taken as the measure of the degree of the conducting power of the substance employed. 673. To submit liquids to this kind of examination, M. Rousseau places them in small metallic cups, communicating by their foot w.th the needle and the ball: he then places in the liquid one of the extremities of the metallic wire, covered with gum lac, that the same surface of metal may always be in contact with the fluid, and measures the duration of the needle's motion from the moment when the communication is established with the pile by the other extremity of the wire. 674. By submitting the fixed vegetable oils employed in the arts and in domestic economy to this kind of proof, M. Rousseau has established a very singular fact, which may be useful in commerce; it is, that olive oil possesses a very inferior degree of conducting power to that of all other vegetable or animal oils, which nevertheless present, in all their physical properties, the strongest analogies to that substance. For instance, every thing being equal in both cases, olive oil required forty minutes to produce a certain deviation, while poppy oil, or the oil of the beech-mast, required only twenty-seven seconds to produce the same deviation. One-hundreth part of any other oil added to oil of olives reduces the time to ten minutes. It would, therefore, be easy to discover, by means of this instrument, the smallest traces of any oil fraudulently mixed with oil of olives. 675. If the proportion of the foreign substance be considerable, the difference of time necessary to produce the maximum of effect would no longer be sufficiently great, and could not be measured with sufficient precision to indicate the proportion of the elements, but the apparatus might easily be modified so as to adapt it to this kind of determination. 676. The solid fats are worse conductors than the animal oils, arising, no doubt, from the large proportion of stearine contained in the former; for M. Rousseau is satisfied, by comparative trials with stearine and elaine, prepared by M. Chevreul, that the conducting power of the latter much exceeds that of the former. The fat of an animal becomes a worse conductor in proportion to the age of the individual which affords it. 677. By means of the same apparatus, we may also observe a considerable difference between resin, gum-lac, and sulphur, the most insulating of all known substances, and silk, crystal, and common glass. 678. M. Rousseau has not found any difference in the conducting power of liquids, whether spirituous or aqueous, acid, alkaline, or neuter, the time required by the needle to arrive at the maximum of deviation being too short, in every case, to ascertain the inequality of its duration. But a modification of the apparatus, similar to that for determining the proportions in an oleaginous mixture, would easily point out that difference. 679. It would be equally possible, and very curious, to try the effect of the two kinds of electricity on different substances; all that would be necessary would be to place the two poles alternately in connexion with the ground. According to Ermann's results, it is probable that a difference would be found between most sub stances. INDE X. ALKALIES, decomposition of the, 156. AMALGAM of potassium and sodium, to procure, 158. AMMONIUM, to form amalgam of, 165. AMPERE, M., his electrical needle, 458. Facts discovered by him, 331. 342, 343. His galvanometer, 331. ANTINORI, Ridolfi, and Gazzeri, M.M., their experiments in electro-magnetism, 391. ARAGO, M., attraction of iron filings by the connecting wire of the battery, 335, 336. BARLOW, Mr., his method of communicating magnetism to needles, 410. His experiments in electro-magnetism, 405. BATTERY, Voltaic, circuit made through water, 119. 319. Experiments on the great, of the London Institution, 386. Voltaic, best conductors for discharging the, 318. BERZELIUS, M., electro-magnetic experiments by, 393. Experiments to prove that oxidation is not the cause of the electricity of the Voltaic apparatus, 109. BERZELIUS and Pontin, M.M, experiments relative to the expansion of mercury, 163. BERZELIUS, Pontin, and Sir H. Davy, experiments on earths, 168. BICHAT, M., his galvanic experiments on frogs, 241. BINARY PILE Constructed by Zamboni, 99. To restore its action, 166. BIOT's, M., experiments, 354. BIOT and Savart, M.M., on determining the law by which a connecting wire acts on magnetised bodies, 345. BOISGERAUD, M., his experiments in electro-magnetism, 341. CARLISLE, Mr., his first experiments upon the moist pile, 138. CAVENDISH, Mr., conductibility of iron, 237. CHILDREN, Mr., powerful Voltaic apparatus by, 266. His experiments, 267-280. 284-288. 290-303. CHIME, electrical of Mr. Forster, 124. Mr. Singer's, 125. COLUMN, electric, by M. De Luc, 122. Mr. Singer's experiments on the, 123. Effects of, upon a gold leaf electrometer, 126. Construction of, for making observations, 128. Precaution to be observed for its constant and immediate action, 129. COMBUSTION of charcoal by the Voltaic battery, 214. CONDUCTORS, best, 148. 222. Best, for discharging the Voltaic battery, 318. CRIMINAL, Dr. Ure's experiments on a, 250-265. DAVY, Sir H., his experiments relating to the separation of gases from the wires proceeding from the battery, 152. Experiments on earths, 168. Communicating magnetism to steel needles by the conducting wire, 364. Repeats Oersted's experiments, 363. 382, 384. Electro-magnetic rotation of mercury, 396. DECOMPOSITION, Voltaic, 171. DE LA RIVE, M., his apparatus, 460. DE LUC, M., development of the relation of the va rious parts of a Voltaic apparatus to the different effects it produces, 109. His experiments, 110. His first dissection of the pile, ib. Second dissection, 111. Third dissection, 114. His theory of the Voltaic pile, 116. Electric column, 122. DIAMOND, experiments on, 304. EARTHS, experiments on, by Messrs. Pontic and Berzelius, and Sir H. Davy, 168. ELECTRIC COLUMN, M. De Luc, 122. Mr. Singer's experiments on the, 123. Construction of the instrument, ib. ELECTRICAL CEMENTS, preparation of, 200. ELECTRICAL CHIME of Mr. Forster, 124. Mr. Singer's, 125. ELECTRICAL CURRENTS, M. Ampère on, 342. ELECTRICITY, its effects on frogs, discovered by Galvani, 3. Volta discovers the effect of, on different kinds of metals, 96. Professor Berzelius's experiment to prove that oxidation is not the cause of the electricity of the Voltaic apparatus, 109. Quantity wanted in the Voltaic battery to produce the electro-magnetic effect, 329. ELECTRO-MAGNETISM, M. Oersted's first experiments in, 316.329. M. Boisgeraud's experiments in, 341. M. La Borne's experiments in, 392. Mr. Barlow's experiments in, 406. ELECTROMETER, effects of a column upon the gold leaf, 126. EXPERIMENTS, electro-magnetic, 320-325. 331. 333. 335. 337. 343-346. 350. 354-359. 361. 363-382. 384-386. 389. 391-404. 406. 410. Voltaic, 172-184. 186-192. 241. 267-280. 284. 288. 290-303. FILINGS, attraction of, by the connecting wire of the battery, 335. 363. FORSTER, Mr., his electrical chime, 124. Mr. Singer's, 125. FROGS, effects of electricity on, discovered by Galvani, 3. M. Lehot's experiments on, 58. M. Valli's experiments on, 8-28. M. Humboldt's experiments on, 29. M. Bichat's galvanic experiments on, 241. GALVANI, L., discovers the effects of electricity on a frog, 3. GALVANIC PILE of Zamboni, 99. GALVANISM, M. Lehot's memoir on, 56. Its effects on taste by M. Lehot, 60. Experiments which form the basis of M. Lehot's theory of, 77-94 Mr. Singer's first experiments, 108. GALVANOMETER, M. Ampère's, 331. GASES, Sir H. Davy's experiments relating to the se- GA77ERI, Ridolfi, and Antinori, M.M., their experi- HUMBOLDT, M., his experiments on frogs, 29. His IRON, conductibility of, 237. LA BORNE, M., his electro-magnetic experiments, LEHOT, M., his memoirs on galvanism, 56. Effects MAGNETIC virtue given to metallic bodies when the MAGNETISM, communicating it to steel needles by MERCURY, Messrs. Berzelius and Pontin's experi- METALS, Volta discovers the effect of electricity on 24. NEEDLE, one magnetised by the Voltaic battery NERVES, Dr. Wilson Philip, on the influence of the NICHOLSON, Mr., his first experiments upon the OERSTED, M., his early experiments in electro-mag- OXIDATION, Professor Berzelius's experiment to PEPYS'S, Mr., Voltaic battery of, 202. PFAFF, M., his memoir on galvanism, 44. His ob- PHILIP, Dr. W., influence of the Voltaic battery in PILE, Voltaic, 97. Zamboni's galvanic, 99. To PONTIN and Berze.ius, M.M., experiments relative RABBIT, M. Valli's galvanic experiments on a, 23. RIDOLFI, Gazzeri, and Antinori, M.M., their expe- ROBISON, Professor, arrangement of a series of ROTATION, electro-magnetic, of mercury, 396. SAVART and Biot, M.M., on determining the law by SINGER, Mr., his first experiments, 108. On the SOLUTIONS, best calculated for the Voltaic battery, SPARK, influence of the Voltaic, on gases, 216. SPIRALS, M.M., Arago and Ampère's experiments SPIRAL WIRE, M. Prechtl's experimental illustration STEEL BAR, how to magnetise, 406. TASTE, effects of galvanism on, by M. Lehot, 60. URE, Dr., experiments on a criminal, 250-265. Effects of electricity on different kinds of metals, 96. VOLTAIC BATTERY, solutions best calculated for the, VOLTAIC SPARK, influence of, on gases, 216. WIRE, effects produced by the conducting, of the ZAMBONI, his galvanic pile, 99. To restore its ac ELECTRUM, Gr. ŋλerтpov. Amber: mixed metal, according to some authors. ELECTRE, ELECTRICITY, and below. She of whose soul, if we may say 'twas gold, Her body was the electrum and did hold Many degrees of that. or a See Donne. ELECTRUM, Lat. "HλEKTρov, Gr. Electrum, according to Ovid, was that resinous substance now called amber; of which there are two kinds, the white and the yellow. Sometimes its color approaches to a hyacinthine red. Also, according to Pliny (lib. xxx. cap. 4), a mixture of gold and silver, of which the fifth part was silver, According to other ancient writers, they had three varieties of substances called electrum, that were used in the arts; namely, glass, a compound metal, and succinum. In the Homeric poems electrum is often mentioned, which seems to have been succinum, the yellow or white amber. According to Eustathius the ancients used sometimes to call gold by this name, probably from its brilliancy, the word krwp signifying the sun. Pliny thinks that the alloy is the same that Homer mentions in the fourth book of the Odyssey, in describing the palace of Menelaus, which he says was ornamented with gold, electrum (ÿλéтpov), silver, and ivory. The scholiast upon Aristophanes, supposes that the electrum of Homer was glass, but there is nothing in any of his works to warrant such a supposition, for glass is not designated by any character. It is more probable that electrum was yellow amber, which has a resplendent sunny brilliancy according with its Greek name; and Herodotus mentions that succinum or amber was known to the ancients. Pliny says, all gold is naturally alloyed by silver in various proportions; some containing a tenth, some a ninth, and some an eighth part. Wherever the silver amounts to a fifth of the mass, the compound is called electrum; this alloy may also be prepared artificially, by adding to gold the requisite proportion of silver. But if this latter exceeds a fifth of the whole, the mass ceases to be malleable. The nature of electrum is to reflect a richer lustre by lamp-light than pure silver does. That which is native has also the additional property of detecting poisons, iridescent rings passing rapidly over the surface of the cup, accompanied by a noise like that of hot metal plunged in water. Electrum was not only used for ornamental plate, but was occasionally employed for coin, at least for medals. Thus Lampridius, in his life of Alexander Severus, says that that prince caused medals to be struck in honor of Alexander the Great, both of electrum and gold. (Electreos aliquantos, sed plurimos tamen aureos.) The Romans themselves appear to have preferred the white lustre of silver to the yellow radiance of gold, &c. probably this taste together with the imperfection of the art of assaying, as practised by them, aided also by an idle superstitious notion of the efficacy of electrum in detecting poison, contributed to give to this alloy a temporary celebrity. Modern taste, however, prefers the native lustre of the noble metals in all their purity to any alloy of them with each other, nor is it probable, that the Roman electrum will ever again be met with at VOL. VIII. the mint or on the sideboard. There are many coins of this alloy of the kings of Bosphorus, some small ones of Syracuse, and many Celtic and of ancient Gaul. ELECTUARY, n. s. Fr. and Belg. electuaire; Ital. elettuario; Span. and Port. letuario; Lat. electuarium; all from Gr. EkλEKTYρLOV, ERXEYW, eligo, to choose-Minsheu. But Vossius and Gesner prefer Eλayμa, from εkλεixe, to lick; as the etymology. A form of medicine made of conserves and powders, in the consistence of honey. The modern pharmacopoeias treat of these articles as confections. We meet with divers electuaries, which have no ingredient, except sugar, common to any two of them. Boyle. Electuaries made up with houey or syrup, when the consistence is too thin, ferment: and when too thick, candy. By both which the ingredients will be altered or impaired. Quincy. ELEEMOSYNA ARATRI, ELEEMOSYNA CARUCARUM, or pro aratris, in our ancient customs, a penny which king Ethelred ordered to be paid for every plough in England towards the support of the poor. It is sometimes also called eleemosyna regis, because first appointed by the king. ELEEMOSYNARIUS, in old records, the almoner, or officer who received the eleemosynary rents and gifts, and distributed them to charitable uses. See ALMONER. ELEEMOS'YNARY, n. s. & adj. Gr. eλeμovn; ab ελɛos, compassion. One who lives upon alms: as an adjective it means given in charity or living upon it. It is little better than an absurdity, that the cause should be an eleemosynary for its subsistence to its effects, as a nature posterior to and dependent on itself. Glanville's Scepsis. In the year 1430, it appears that the eleemosynary boys, or choristers, of that monastery acted a play. Warton. History of English Poetry. EL'EGANCE, n. s.` EL'EGANCY, ELEGANT, adj. Fr. elegance; Ital. eleganza; Lat. elegantia, elegans, ab eligere, to choose. The beauty of propriety, not of greatness, says Dr. Johnson. Rather that which is selected or chosen because ELEGANTLY, adv. it pleases: hence applied particularly to objects in discernment, or nice in taste. of taste. Milton uses the adjective for accurate St. Augustine, out of a kind of elegancy in writing, makes some difference. Raleigh's History. They describe her in part finely and elegantly, and in part gravely and sententiously. Bacon. Lovers are anxious to trick themselves out; to be spruce in their apparel; to have their locks neatly combed and curiously curled; to adorn their shoes with elegant ties; to be point device in all their Burton. accoutrements. |