Both these solutions, when concentrated, crystallize, a mass being deposited, consisting of a congeries of slender prisms. Both salts are corrosive, deliquescent, and soluble in water. If the solution of the per-nitrate is poured into water, a partial decomposition happens, similar to that of sulphate of mercury, and a yellow insoluble sub-per-nitrate of mercury is precipitated. Nitrate of mercury is decomposed by the alkalies and earths; and in these decompositions are well displayed the differences which arise from different states of oxidation of the metal. By potash, soda or lime, added to the solution of the proto-nitrate, a precipitate of a grayish color, with a tinge of yellow, is thrown down: from the solution of the per-nitrate the precipitate is yellow, more or less bright. These precipitates are sub-nitrates, the oxide, separated by the alkali, retaining a portion of the acid combined with it. The action of ammonia on these solutions is more peculiar. From the solution containing the mercury at a high state of oxidation, it throws down a white precipitate, which is a ternary combination of the oxide, with portions of the acid and alkali. From the solution at which the metal exists at the minimum of oxidation, it throws down a precipitate of a dark gray or blue color. The gray precipitate by ammonia (oxidum hydrargyri cincreum of the pharmacopoeias) is a preparation much used in medicine. It is a mild mercurial, and is very similar, in its operation on the system, to the mercurial preparations formed by trituration. To obtain it of uniform composition, it is necessary to use every precaution to moderate the action of the nitric acid on the metal, as by free dilution with water, and by avoiding the application of heat. A fulminating preparation of mercury is obtained by dissolving 100 grains in one and a half ounce by measure of nitric acid. This solution is poured cold into two ounces by measure of alcohol in a glass vessel, and heat is applied till effervescence is excited, though it ordinarily comes on at common temperatures. A white vapor undulates on the surface, and a powder is gradually precipitated, which is immediately to be collected on a filter, well washed, and cautiously dried. This powder detonates loudly by gentle heat or slight friction. It has been very much used of late as the match-powder, or priming, for the percussion caps of the detonating locks of fowling-pieces. Two grains and a half of it, mixed with one sixth of that weight of gunpowder, form the quantity for one percussion cap, ac36

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cording to the researches of Aubert, Pelissier and Gay-Lussac. In preparing this powder in quantities, the fulminating mercury should be moistened with thirty per cent. of water, then triturated in a mortar, and thereafter mingled with the sixth part of its weight of gunpowder. Matches of this kind resist damp very well, and take fire after several hours immersion in water. The detonating match, or priming powder, made with chlorate of potash, sulphur and charcoal, has the inconvenience of rusting and soiling the fowlingpieces, and thence causing them to miss fire; whereas, with the above fulminating powder, 100 shots may be discharged successively. The mercurial percussion caps are sold now in Paris for three francs and a half per thousand. The acetic and most other acids combine with the oxide of mercury, and precipitate it from its solution in the nitric acid. Muriatic acid does not act on mercury. When mercury is heated in chlorine, it burns with a palered flame, and the substance called corrosive sublimate is formed. This deuto-chloride may also be formed by mixing together equal parts of dry bi-deuto-sulphate of mercury and common salt, and subliming. The corrosive sublimate rises, and incrusts the top of the vessel, in the form of a beautiful white semitransparent mass, composed of very small prismatic needles. Its specific gravity is 5.14. Its taste is acrid, stypto-metallic, and eminently disagreeable. It is a deadly poison. Twenty parts of cold water dissolve it, and less than one of boiling water. It is composed of 73.53 mercury and 26.47 chlorine. It may be recognised by the following characters: It volatilizes in white fumes, which seem to tarnish a bright copper-plate, but really communicate a coating of metallic mercury, which appears glossy white on friction. When caustic potash is made to act on it with heat in a glass tube, a red color appears, which by gentle ignition vanishes, and metallic mercury is then found to line the upper part of the tube in minute globules. Solution of corrosive sublimate reddens litmus paper, but changes sirup of violets to green. Bicarbonate of potash throws down from it a deep brick-red precipitate, from which metallic mercury may be procured, by heating it in a tube. Lime-water causes a deep-yellow precipitate, verging on red. Water of ammonia forms a white precipitate, which becomes yellow on being heated. With sulphureted hydrogen and hydrosulphurets, a black, or blackish-brown precipitate appears. Nitrate of silver throws down the curdy

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precipitate characteristic of muriatic acid; and the proto-muriate often gives a white precipitate. From 6 to 12 grains were the mortal doses employed by Orfila, in his experiments on dogs: they died in horrible convulsions, generally in two hours; but when with a larger quantity, the whites of eight eggs were thrown into the stomach, the animals soon recovered after vomiting. The effect of this antidote is to convert the corrosive sublimate into calomel. Sulphureted hydrogen may also be employed along with emetics. The proto-chloride of mercury (mercurius dulcis, or calomel), is usually formed from the deuto-chloride, by triturating four parts of the latter with three of quicksilver till the globules disappear, and subjecting the mixture to a subliming heat. By levigating and edulcorating with warm water the sublimed grayish-white cake, the portion of soluble corrosive sublimate which had escaped decomposition is removed. It may also be made by adding solution of proto-nitrate of mercury to solution of common salt; the proto-chloride, or calomel precipitates. The following is the process used at Apothecaries' Hall, London: -50 pounds of mercury are boiled with 70 pounds of sulphuric acid to dryness, in a cast-iron vessel; 62 pounds of the dry salt are triturated with 404 pounds of mercury until the globules disappear, and 34 pounds of common salt are then added. This mixture is submitted to heat in earthen vessels, and from 95 to 100 pounds of calomel are the result. It is washed in large quantities of distilled water, after having been ground to a fine and impalpable powder. When proto-chloride of mercury is very slowly sublimed, foursided prisms, terminated by prisms, are obtained. It is nearly tasteless and insoluble, and is purgative in doses of five or six grains. Its specific gravity is 7.176. Exposure to air darkens its surface. It is not so volatile as the deuto-chloride. Nitric acid dissolves calomel, converting it into corrosive sublimate. Proto-chloride of mercury is composed of mercury 84. 746, and chlorine 15.254. There are two iodides of mercury; the one yellow, the other red; both are fusible and volatile. The yellow, or protiodide, contains one half less iodine than the deutiodide; the latter, when crystallized, is a bright crimson. They are both decomposed by concentrated sulphuric and nitric acids. The metal is converted into an oxide, and iodine is disengaged. They are likewise decomposed by oxygen, at a red heat.-Mercury, on account of its fluidity, readily combines

with most of the metals, to which it communicates more or less of its fusibility. When these metallic mixtures contain a sufficient quantity of mercury to render them soft at a mean temperature, they are called amalgams. It very readily combines with gold, silver, lead, tin, bismuth, and zine; more difficultly with copper, arsenic, and antimony; and scarcely at all with platina or iron. It does not unite with nickel, manganese, or cobalt; and its action on tungsten and molybdena is not known. Looking-glasses are covered on the back side with an amalgam of tin. (See Silvering.) The medicinal uses of mercury have already been alluded to. The amalgamation of the precious metals, water gilding, the making of vermilion, the silvering of looking-glasses, the construction of barometers and thermometers, are the principal uses to which this metal is applied. Scarcely any substance is so liable to adulteration as mercury, owing to its property of dissolving completely some of the baser metals. This union is so strong, that they even rise along with it in vapor when distilled. Its impurity, however, can generally be detected by its dull aspect; by its tarnishing, and becom ing covered with a coat of oxide, on long exposure to the air; by its adhesion to the surface of glass; and, when shaken with water in a bottle, by the speedy formation of a black powder. Lead and tin are frequent impurities, and the mercury becomes capable of taking up more of these, if zinc or bismuth be previously added. In order to discover lead, the mercury may be agitated with a little water, in order to oxidize that metal: pour off the water, and digest the mercury with a little acetic acid; this will dissolve the oxide of lead, which will be indicated by a blackish precipitate, with sulphureted water; or to this acetic solution add a little sulphate of soda, which will precipitate a sulphate of lead, containing, when dry, 70 per centum of metal. Bismuth is detected by pouring a nitric solution, prepared without heat, into distilled water; a white precipitate will appear, if this metal be present. Tin is manifested, in like manner, by a weak solution of proto-muriate of gold, which throws down a purple sediment; and zine by exposing the metal to heat.-Ores of Mercury. The native mercury and the sulphuret are the only two ores explored for the extraction of this metal. The first of these is found in globules, disseminated through different rocks, adhering to the sides of cavities and fissures in the form of little drop, and rarely accumulated in basins

of considerable dimensions, so as to admit of being dipped up in pails; though it never occurs in sufficient quantity to form the sole object of exploitation. Occasionally it is found amalgamated with silver, containing one third its weight of this metal; in this condition, it is rarely observed crystallized under the form of the rhombic dodecahedron. The sulphuret is the common ore, which furnishes nearly all the mercury of commerce. It occurs, crystallized, in rhomboids, and six-sided prisms and tables; color cochineal-red; lustre adamantine and splendent; translucent; streak scarlet-red, shining; harder than gypsum, sectile, and easily frangible; specific gravity, 6.7 to 8.2. It also occurs massive and compact, and often blended with bituminous matter, which communicates to it a liver-brown or black color, whence the name of hepatic cinnabar. This ore is very rich, and affords, by analysis, 84 or 85 per centum of mercury; that which is bituminous gives 81 per centum. The muriate of mercury, or horn quicksilver, is so rare, and presents itself in such small quantities in the mines, as scarcely to receive the attention of the miner, and it is sought after only by the mineralogist. It occurs in incrustation, and rarely crystallized in quadrangular prisms, terminated by pyramids. It is translucent, with a lustre between adamantine and vitreous, and is sectile. It consists of 76 oxide of mercury, 16.4 muriatic acid, and 7.6 sulphuric acid. The ores of mercury are more frequent in secondary than in primitive rocks, and are found particularly in sandstones, bituminous shales, and argillite, often accompanied by organic remains. In general, mercury is a metal which cannot be said to have a wide distribution, and the mines which furnish it in quantity are few. The principal are those of Idria, in the Austrian dominions, discovered in 1497, and which chiefly afford a bituminous sulphuret of this metal. These mines have already been explored to a depth not far from 1000 feet. They are capable of furnishing annually 6000 quintals of metal; but the Austrian government, in order to maintain the value of the metal, have limited their produce to 1500 quintals per annum. Their total produce from 1809 to 1813, a period of 56 months, was 1,419,425 pounds of mercury; 270,029 pounds of vermilion; 76,225 pounds of lump cinnabar; 6,400 pounds of calomel; 2,867 pounds of red precipitate, and 2,450 pounds of corrosive sublimate. The memorable conflagration of these mines in 1803 was

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extinguished only by filling their chambers and galleries with water, and the mercury which was sublimed during that catastrophe occasioned the most dreadful diseases among more than 900 persons. Next to the mines of Idria come those of Almaden, in the province of Manche, in Spain, and which are nearly as rich as those of Idria. Their mean annual product is about 5000 quintals of quicksilver. These celebrated mines, near which are also those of Cuebas and Almadenejos, were known to the Romans, and, it is presumed, are those alluded to by Pliny, under the name of the mines of the territory of Sisapanus. After having been, for a great number of years, leased out to the merchants of Ausbourg, they are now explored on account of the government, and their product is exclusively applied to the amalgamation of gold and silver in the mines of Mexico and South America. The mines of the palatinate, situated upon the left bank of the Rhine, approach next in importance to those of Idria and Almaden. Their annual product is estimated at about half that of the Spanish mines. There exist in Hungary, in Bohemia, and in many other parts of Germany, small explortations for mercury, of which the total yield is about 400 quintals per annum. The mines of Guanca Velica, in Peru, have afforded an immense supply of quicksilver for the purposes of amalgamation in the new world. Between the years 1570 and 1800, they are said to have furnished 537,000 quintals of this metal; and their actual product is, at present, rated at 1800 quintals. The ores of mercury are found in several places in Mexico, but are nowhere wrought to any extent. In 1590, mercury was sold in Mexico at £40 10s. per cwt.; in 1750, it had diminished to £17 15s.; in 1782, a further reduction had taken place, the price then being £8 17s. 6d. The consumption was estimated in the year 1803 (for Mexico), when the mines were in full work, as being 2,000,000 pounds per annum. We have no ores of mercury in the U. States.

MERCY, François de, one of the most distinguished generals in the 30 years' war, was born at Longwy, in Lorraine, and rose in the service of the elector of Bavaria, through the successive ranks. After having defeated general Rantzau at Tuttlingen, he was appointed, with the rank of Bavarian lieutenant-general and imperial field-marshal, to the command of the combined forces, and captured Rotweil and Ueberlingen. In the succeeding year (1644), Friburg fell into his

hands, and he threw up a fortified camp in its vicinity. The great Condé attacked him in this position, and, after a combat of three days, compelled him to retire. Turenne pursued him, but the retreat was so ably conducted, that the French general was unable to obtain any advantage over him. May 5 (April 25), 1645, he defeated Turenue, at Marienthal (Mergentheim), and fell, August 3, in the battle of Allersheim, near Nordlingen. He was buried on the field, and a stone was raised with the inscription Sta, viator, heroem calcas. Rousseau, in his Emile (liv. iv), very justly remarks, that the simple name of one of his victories would have been preferable to this pompous sentence, borrowed from antiquity.

MERCY, Florimond Claude de, a grandson of the preceding, born in Lorraine, 1666, entered the service of the emperor Leopold, 1682, and distinguished himself as a volunteer in the defence of Vienna against the Turks. His gallantry, particularly in the battle of Zenta, 1697 (see Eugene), was rewarded with the rank of major. He afterwards served with equal distinction in Italy and on the Rhine. In 1705, he stormed the lines of Pfaffenhofen, and compelled the French to retreat under the canon of Strasburg. In 1706, he covered Landau by his skilful manœuvres, and supplied it with provisions and troops. In 1707, he defeated general Vivans, at Offenburg; but, in 1709, having penetrated too far into Alsace, was entirely defeated at Rumersheim. In 1716, he, commanded against the Turks, as field-marshal, and took part in the victories of Peterwardein and Belgrade. In 1719, he commanded, with equal success, in Sicily, against the Spaniards, and, during the peace, exerted himself in improving the condition of the Bannat. In 1734, he received the command in Italy, and occupied the duchy of Parma; but fell, while leading the attack, in person, on the village of Croisetta. His remains were interred at Reggio.

MERGANSER (mergus); a genus of aquatic birds, consisting of five species. These birds are wild and untamable, migrating, according to the season, from cold to temperate climates. They keep in flocks, the adult males usually by themselves, leaving the young with the females. They are extremely voracious, destroying immense numbers of fish. They build among grass, near fresh water: the nest is lined with down, and contains from eight to fourteen eggs. The male keeps near the nest, though the female alone

incubates. They swim with the body very deep in the water, the head and neck only appearing; dive by plunging, and remain under water for a long time. They walk badly; fly well, and for a long time. Their flesh is dry, and of a bad flavor. The species inhabiting the U. States are the goosander (M. merganser); minor white, uninterrupted; bill and feet red; nostrils medial; found in both continents; not uncommon in the U. States. Red-breasted merganser (M. serrator); minor white, crossed with black; bill and feet red; nostrils basal; a long, slender, pendent crest; found in both continents; common in the Middle States during the spring and autumn. Hooded merganser (M. cucullatus); minor white, crossed with black; bill blackish red; feet fleshcolor; a large circular crest; peculiar to North America, breeding in the north, wintering in the south; common in the Middle States during the spring and autumn. Smew or white nun (M. albelius); minor black, crossed with white; bill and feet bluish. This species is also found in both continents, and is the most beautiful of the genus. It is more common in Europe than in America. In the Middle States, it is very rare. (See Wilson's Ornithol., Pennant's Arctic Zool.)

His

MERIAN, Matthew, senior, born at Basle, in 1593, studied at Zürich, under Dietrich Meyer, and at Oppenheim, under Theodore de Bry, settled at Frankfort on the Maine, and died in 1651. His principal engravings consist of views of the chief cities of Europe, particularly those of Germany, with descriptions, and are remarkable for the excellence of their perspective. other works are landscapes, historical scenes, the chase, &c.-His son Matthew, born at Basle, 1621, was a good painter of portraits. He studied at Rome, 1644, travelled in England, the Low Countries, France, &c., and died in 1687.-Maria Sibylla, a daughter of the elder Matthew, was born at Frankfort, in 1647. studied under her step-father Morefels, and Mignon, and was distinguished by the taste, skill and accuracy with which she painted flowers and insects in water colors. Her zeal for this department of painting induced her to make a voyage to Surinam, for the purpose of observing the metamorphosis of the insects of that country; and, after a residence of two years, she returned with a large collection of drawings of insects, plants and fruits on vellum. Her works are Erucarum Ortus, Alimentum, et Metamorphosis; History of the Insects of Europe; and Metamor

She

phosis Insectorum Surinamensium, with 60 plates. She died at Amsterdam, 1717. One of her daughters published a new edition of the last named work, which her mother was preparing at the time of her death.

MERIDA, OF YUCATAN; one of the states of the Mexican confederacy. (See Yucatan, and Merico.)

MERIDIAN, in astronomy (from the Latin meridies, mid-day), is a great circle of the celestial sphere, passing through the poles of the earth and the zenith and nadir, crossing the equator at right angles, and dividing the sphere into an eastern and western hemisphere. When the sun is on this circle, it is noon or mid-day, to all places situated under that meridian, whence the derivation of the word, as above stated.

Meridian, in geography; a corresponding terrestrial circle in the plane of the former, and which, therefore, passes through the poles of the earth. All places situated under the same meridian have their noon or midnight at the same time; but, under different meridians, it will arrive sooner or later, according as they are situated to the eastward or westward of each other; viz. the sun will be upon that meridian soonest which is most to the eastward, and that at the rate of an hour for every 15 degrees.

First Meridian is that from which all the others are reckoned, which, being totally arbitrary, has been variously chosen by different geographers. Ptolemy makes his first meridian pass through the most western of the Canary islands; others have chosen cape Verd; some the Peak of Teneriffe, others the island of Ferro, &c.; but most nations now consider that the first meridian which passes over their metropolis, or their principal observatory. Thus the English reckon from the meridian of Greenwich; the French from Paris; the Spanish from Madrid; the Americans from Washington, &c.

Meridian of a Globe is the brazen circle in which it turns, and by which it is supported. The Brazen Meridian is divided into 360 equal parts, called degrees. In the upper semicircle of the brass meridian these degrees are numbered from 0 to 90, or from the equator towards the poles, and are used for finding the latitudes of places. On the lower semicircle of the brass meridian, they are numbered from 0 to 90, from the poles towards the equator, and are used in the elevation of the poles.

Meridian Line is a north and south line,

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the exact determination of which is of the greatest importance in all cases relating to astronomy, geography, dialling, &c., because on this all the other parts have their dependence. The most celebrated meridian line is that on the pavement of the church of St. Petronio, in Bologna, which was drawn to the length of 120 feet, by the celebrated Cassini. Without knowing the meridian line of a place, it would be impossible to make a dial, set a clock, or measure degrees on the earth's surface. (For the measurement of degrees of the meridian, see the article Degrees, Measurement of)

Meridian Line, on a dial, is the same as the 12 o'clock hour line.

Magnetic Meridian; a great circle passing through the magnetic poles. (See Magnetism.)

Meridian Altitude; the altitude of any of the heavenly bodies when they are upon the meridian.

MERINO SHEEP. (See Sheep.)

MERLIN, Ambrose, a British writer, who flourished about the latter end of the fifth century. The accounts we have of him are so mixed up with fiction, that to disentangle his real life from the mass would be impossible. He was said to be the son of a demon and a daughter of a king of England who was a nun. His birthplace was Carmarthen, in Caledonia. He was instructed by his father in all branches of science, and received from him the power of working miracles. He was the greatest sage and mathematician of his time, the counsellor and friend of four English kings, Vortigern, Ambrosius, Uther Pendragon, and Arthur. Vortigern, at the advice of his magicians, had resolved to build an impregnable tower, in order to secure himself against the Saxons; but the foundation was scarcely laid, when the earth opened by night and swallowed it up. The magicians informed the king, that to give firmness to the foundation, he must wet it with the blood of a child born without a father. After much search, the young Merlin was brought to the king. After Merlin had heard the dictum of the magicians, he disputed with them, and showed them that under the foundation of the tower was a great lake, and under the lake two great raging dragons, one red, representing the British, one white, representing the Saxons. The earth was dug open, and no sooner were the dragons found, than they commenced a furious battle; whereupon Merlin began to weep, and to utter prophecies respecting the future state of England. The mira