to others, that no compound of them has yet been effected. The most common obstacles to alloying, arise from the difference in fusibility and volatility. Yet some metals are known whose melting point is nearly the same, which refuse to unite. No two bodies will combine, unless their affinity or reciprocal attraction be stronger than the cohesive attraction of their individual particles. It is in order to overcome this cohesion of the solid bodies, and to render affinity predominant, that they are penetrated by caloric. If one be very difficult of fusion, and the other very volatile, they will not unite unless the reciprocal attraction be exceedingly strong. But if their degree of fusibility be almost the same, it is otherwise. Alloys in their physical properties have the closest relations with the metals. They are a solid at the temperature of the atmosphere, except some few amalgains: they possess metallic lustre, are opaque, and dense in a greater or less degree according to the metals which compose them. They are excellent conductors of electricity, and crystallize more or less perfectly. Some alloys are brittle, others ductile and malleable: some have a peculiar odour, and some are sonorous and elastic. An alloy consisting of metals differently fusible, is usually malleable while cold, but brittle while hot. We see this exemplified in the case of brass. With regard to the density of an alloy, we observe that it is sometimes greater, and sometimes less than the mean density of its component parts, which evinces a diminution or augmentation of volumes, at the instant of their union. The relation between the expansion of the separate metals and that of their alloys has been in some cases investigated. Alloys containing volatile metal are decomposed, either in whole or in part; a fact which is exemplified at a strong heat, in the case of arsenic, mercury, tellurium and zinc. Those that consist of two metals differently fusible may be often decomposed by eliquation, or exposing them to a temperature capable of melting only one of them. This mode is employed to extract silver from copper. Argentiferous copper is melted with 31⁄2 times its weight of lead; and the triple alloy being exposed to a sufficient heat, the lead carries off the silver in its fusion, and leaves the copper under the form of a spongy lump. By a subsequent operation the silver is recovered from the lead. a 'Some alloys,' says an intelligent author, 'oxidize more readily by heat and air, than when the metals are separately treated. Thus 3 of lead, and 1 of tin, at a dull red, burn visibly, and are immediately oxidized. Each by itself, in the same circumstances, would oxidize slowly, and without the disengagement of light.' The formation of an alloy must be regulated by the nature of the particular metals; the degree of affinity between metals may be in some measure estimated by the relative facility with which, when of different degrees of fusibility or volatility, they unite, or with which, when united, they can be separated by heat. The degree of tendency to separate into different proportional alloys, by long continued fusion, may also throw additional light on this subject. Mr. Hatchett in his researches on metallic alloys, remarked, that gold made standard, with the usual precautions, by silver, copper, lead, antimony, &c. and then cast into vertical bars, was by no means a uniform compound; but that the top of the bar, corresponding to the metal at the bottom of the crucible, contained the larger proportion of gold. Hence, for thorough combination, two red-hot crucibles should be employed; and the liquefied metals should be alternately poured from the one into the other. And to prevent unnecessary oxidizement by exposure to air, the crucibles should contain, besides the metal, a mixture of common salt and powdered charcoal. The melted alloy should also be stirred occasionally with a rod of pottery. The most direct evidence of a chemical change having taken place in the two metals by com.bination, is when the alloy melts at a lower temperature than the fusing points of its components. Iron, which alone is nearly infusible, when alloyed with gold acquires almost the fusibility of this metal. Tin and lead form solder, which is more fusible than either of its components, and the triple compound of tin, lead, and bismuth illustrates this remark in a still more striking manner. The analogy is here strong, with the increase of solubility which salts acquire by mixture, as is exemplified in the uncrystallizable residue of saline solutions. Sometimes two metals will not directly unite, which yet, by the intervention of a third, are made to combine. Thus, mercury and iron have been made to amalgamate by previously uniting the iron to tin or zinc. The tenacity of alloys, generally speaking, is inferior to the mean of the separate metals. One part of lead will destroy the compactness and tenacity of a thousand of gold. Brass made with a small proportion of zinc, is more ductile than copper; but when one-third of zinc enters into its composition, it becomes brittle. In common cases, the specific gravity affords a good criterion whereby to judge of the proportion in an alloy, consisting of two metals of different densities. A very fallacious rule has nevertheless been given in some respectable works, for comparing the specific gravity that should result from given quantities of two metals of known densities in a state of alloy, supposing no chemical penetration or expansion of volume to take place. Thus it has been taught, that if gold and copper be united in equal weights, the mathematical specific gravity of the alloy is the arithmetical mean of the two specific gravities. Referring the details to the article specific gravity, the correct rule is as follows: The specific gravity of the alloy is found by dividing the sum of the weights by the sum of the volumes; compared to water, reckoned unity. - Let the sum of the weights be multiplied into the product of the two specific gravities for a numerator, and each specific gravity into the weight of the other body, and the two products added together for a denominator. The quotient then obtained by dividing the numerator by the denominator, compared with this, is the true computed mean specific gravity; and that found by experiment will show whether expansion or condensation of true mean specific gravity is only 12.6. It is evident, that by comparing the former number with chemical experiment, we should be led to infer a prodigious condensation of volume beyond what really occurs, Mr. Hatchett observed upon the density of metals, that when a bar of gold was cast in a vertical position, the density of the metal at the lower end of the bar, was greater than that at the top, in the proportion of 17.364 to 17.035. From the above fact some authors have inferred that melted metal is a compressible fluid, and that particles passing into the solid state under pressure, exert a superior degree of cohesive attraction. On this subject, however, we shall leave the reader to form his own conclusion. Upon the whole, since we are far from knowing all the binary alloys, which are possible, and still further from knowing all the triple, quadruple, alloys, &c. which may exist, we must confess, with Dr. Thomson, that the chemistry of alloys is at present but little understood, and that these compounds at present are much better known to artists and manufacturers than to chemists. The following tabular views from this intelligent author, exhibit the general properties of the different alloys, as far as they have been accurately examined, and with them we shall close the present article. The first of these tables comprehends the alloys of the malleable metals with each other; the second, the alloys of the brittle metals; and the third, the alloys of the malleable and brittle metals. In these tables, the letter M signifies malleable; B, brittle; S, submalleable, used when the alloy is malleable in certain proportions, but brittle in others. O is used when the metals do not unite. The sign + is used when the alloy occupies a greater bulk than the separate metals; the sign - when the alloy occupies a smaller bulk. The first indicates an expansion; the second a condensation. Atterbury's Sermons. The principles, which all mankind allow for true, are innate; those, that men of right reason admit, are the principles allowed by all mankind. Locke. The pow'r of musick all our hearts allow; And, what Timotheus was, is Dryden now. Pope. That some of the Presbyterians declared openly against the king's murder, I allow to be true. Swift. If we consider the different occasions of ancient and modern medals, we shall find they both agree in recording the great actions and successes in war; allowing still for the different ways of making it, and the circumstances that attended it. Addison. The ruin'd spendthrift, now no longer proud, Claim'd kindred there, and had his claims allow'd. Goldsmith's Deserted Village ALLOW, EAST, a river of Durham, which runs into the Tyne. ALLOW, WEST, a river of Northumberland, which runs into the Tyne; also a river of the isle of Anglesea. • ALLUCIUS, in ancient history, a prince of the Celtiberi, to whom Scipio Africanus restored his beautiful bride, who had fallen into his hands in war. Plutarch calls him Lucceius. ALLUDE', v. ALLU'SION, ALLU'SIVELY, } Ad: ludo, to play or sport with, about, or near: referring primarily to what is sportive or playful. Sub ALLU'SIVENESS. sequently it signifies to fur ALLUM BAY lies round the Needles Point, or north-east from the rocks so called, at the west end of the Isle of Wight, on the coast of Hampshire. It has good anchorage, with a sufficient depth of water, not far from the bottom of the bay, and out of the strong run of the tide, which is frequently very rapid here. ALLUMEE, allumé, French, in heraldry, denotes the eyes of an animal when they are represented light or sparkling, and of a different colour from the animal itself, as when they are red, and the animal proper. Also applied to the flame of a torch, when illumined, and the handle itself is of the colour of nature. Whose piercing look did represent a mind Earl of Surry's Poems. Unto laws that men make for the benefit of men, it hath seemed also needful to add rewards; which Against allurement, custom, and a world The golden sun, in splendour likest heav'n, Id. Id. ALLUT, a large village of Ceylon, north-eas! of Candy, from which it is distant about fifteen miles. ALLU'VION, n. Ad: luo, lutum, to wash to; the washing away; the washing up of sand or earth, so as to form a mud soil. Some rivers by insensible alluvions take in and let out the waters that feed them, yet they are said to have the same beds. Howell's Letters. ALLUVION, from adluo, I wash to, comMilton's Par. Lost. pou unded of ad and lavo; in law, a gradual increase of land along the sea-shore, or the banks of large rivers. The civil law places alluvion, among the lawful means of acquisition; and defines it to be a latent, imperceptible accretion. But where any considerable portion of ground is torn away at once by an inundation, and joined to some neighbouring estate, this is not acquired by right of alluvion, but may be claimed again by the former owner. Great alterations are made in the face and limits of countries by alluvions of the sea, rivers, &c. whose plains are sometimes formed by alluvions. Paradise Regained. To shun th' allurement is not hard ing net. The rather to train them to his allure, he told them both often, and with a vehement voice, how they were over-topped and trodden down by gentlemen. Hayward. Each flatt'ring hope, and each alluring joy. ALLUSH, or rather ALUSH, in ancient geography, a place in Palestine, where the Israelites encamped, Numb. xxxiii. 13, supposed by Eusebius, Jerome, and Ptolemy, to have belonged to Idumæa, and to have been situated near Petra, the capital of Arabia Petræa. ALLUSION, from ad, to, and ludere, to play, in rhetoric, a figure originating in a comparison or association of ideas, suggested by some similitude of name, sound, or circumstances. Camden defines allusion a playing with words alike in sound, but unlike in sense; whence words resembling one another become applicable to different subjects; in which sense it is synonymous with punning. Thus the Romans played on their tippling emperor Tiberius Nero, by calling him Biberius Mero; and thus in Quintilian the sour fellow Placidus is called Acidus. But allusion has, in modern times, a more extended and important signification. We cannot illustrate its graver uses better than by the following fine passage of Dr. Ogilvie's respecting religious controversy. If it be the obscure, the minute, the ceremonial parts of religion for which we are contending, though the triumph be empty, the dispute is dangerous; like the men of Ai we pursue, perhaps, some little party that flies before us, and are anxious that not a straggler should escape, but when we look behind us we behold our city in flames.' Pope illustrates its admirable service in irony, alluding to Denton's wellknown passage respecting the Thames : ، ALLY', v. & n. ALLI'ANCE, Fr. alliér, to fasten or attacki attach to; from the Latin Sadligo, to join, unite, by kindred, marriage, friendship, confederacy, or Gisors my gode cite, with alle pe purueiance, R. Brunne, p. 156. To the sun ally'd, Lord Byron's English Bards and Scotch Reviewers. ALLY, (Vizier,) ex-nabob of Oude, was the adopted son of Ausuf ab Dowlah, late nabob of Oude. His reputed father, a wealthy and eccentric prince, who had succeeded to the musnud or throne of Oude, under the protection of the British, was in the habit, whenever he saw a pregPope. The Dunciad, book iii. nant woman whose appearance pleased him, of Flow, Welsted, flow! like thine inspirer, beer: |