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ZEBRA WOOD-ZEOLITE

Zebra Wood. Striped wood found in Guiana and the W. Indies, and used for veneering.

Zebu (BOS INDICUS). Domesticated species of the BOVIDÆ (q.v.), distributed throughout s. Asia, and characterized by the presence of a hump on the withers, long pendulous ears, very short upright horns, varied color, reddish-yellow to white. They are somewhat smaller than the cattle of Europe, and

Zenith Distance. That of a star from the zenith, measured on a great circle.

Zenith Telescope. Instrument much used for determination of latitude. It consists of a telescope having an altitude and azimuth mounting, provided with a delicate level and micrometer, by means of which the difference of zenith distance

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Zebu (Bos indicus).

in India have been bred for specific purposes, resulting in several races, useful for milk, draught, riding, etc. White bulls when branded with the image of Siva are held especially sacred by the Hindus: they are free from labor and restraint, and are not molested even when they commit depredations.

Zebulun. Tenth son of the patriarch Jacob, and ancestor of one of the twelve tribes of Israel.

Zechariah. Jewish prophet, author of 38th O. T. book, ab. 520 B.C., written to encourage the despondent Jews after the return from Babylon. Chapters ix.-xiv. are perhaps much older.

Zedekiah. Last king of Judah 598-588 B.C.; son of Josiah. Rebelling against Nebuchadnezzar of Babylon, his suzerain, he saw Jerusalem taken, the temple burned, his sons slain, and was then blinded and carried to Babylon, there to die in prison. Jer. xxxiv. 2-5.

Zedlitz, JOSEPH CHRISTIAN VON, 1790-1862. Austrian poet and dramatist.

Zedoary. Name given to the roots of several species of Zingiber and Curcuma, native of China and Bengal, resembling ginger in its qualities, but now entirely replaced by the latter.

Zeeland. See ZEALAND.

Zeisberger, DAVID, 1721-1808. Moravian missionary among the Indians of Pa. and Ohio; abundant in labors and sufferings. Delaware Dictionary, 1887; Onondaga Grammar, 1888; Diary, 1888.

Zelaya, JOSÉ SANTOS, b. ab.1845. Pres. of Nicaragua 1893. Zell, BERNHARD, 1715-1779. German traveler in Mexico and Cal. His Reisen, 1771-72, indicated the existence of gold in Cal.

Zell, MATTHAUS, 1477-1548. Reformer at Strasburg. Zeller, EDUARD, b. 1814. Prof. of Theology at Berne 1847 and Marburg 1849, of Philosophy at Heidelberg 1862 and Berlin 1872-94. Philosophy of the Greeks, 1844-52 and later, tr. in 6 vols. 1868-83; Hist. Apostles, 1854, tr. 1875-76; Strauss. 1874. Zeller, JULES SYLVAIN, b. 1820. Prof. Paris 1858; historical writer: especially on Italy and Germany.

Zelter, KARL FRIEDRICH, 1758-1832. German musician, teacher of Mendelssohn; conductor Singakademie in Berlin; founder Royal Institute for church music 1809.

Zenana. Harem or women's apartments in India. Zend. Old Persian dialect, sometimes called Old Bactrian, in which was written the sacred book of Zoroaster, the AVESTA (q.v.). It comprised three books of verse, hymns, prayers, and

laws.

Zendejas, MIGUEL GERONIMO, 1724-1816. Mexican painter, self-taught.

Zenea. JUAN CLEMENTE, 1834-1871. Cuban lyric poet and patriot; executed.

Zenith. Point where the plumb-line produced upward pierces the celestial sphere.

Combination Transit and Zenith Telescope. of two stars may be measured. These stars are so selected that one culminates n. of the zenith, the other s. at approximately equal zenith distances. The measurements so made with the declinations of the stars furnish data for determining the latitude.

Zenker, JONATHAN KARL, 1799-1837. Prof. Jena 1828. Die Pflanzen und ihr wissenschaftliches Studium überhaupt, 1830; Merkantilische Waarenkunde, 1831-35.

Zeno, 5th cent. B.C. Philosopher of Elea, s. Italy; pupil of Parmenides; famous for his denial of the existence of motion and for the paradoxical illustrations of Achilles and the Tortoise, and of the flying arrow, to prove his position.

Zeno, ab.350-260 B.C. Philosopher of Cyprus, founder of the Stoic school or "Porch" at Athens ab. 312 B.C.

Zeno, d.491. Byzantine Emperor 474; Isaurian; son-in-law of Leo I.

Zeno, APOSTOLO, 1668-1750. Italian dramatist, poet, and critic. Plays, 10 vols., 1744; Epistole, 6 vols., 1785.

Zeno, NICOLO, ab. 1340-ab.1391. Venetian seaman, said to have visited Greenland, Newfoundland, and coasted as far s. as Virginia.

Zenobia. Wife of Odenathus, King of Palmyra, Queen of the East 266; defeated and made prisoner by Aurelian 273; led in his triumph 274.

Zenon de Rouvroy, CHARLES ALBERT, 1698-1759. French writer on the American colonies.

Zenteno, CARLOS DE TAPIA, 1698-ab. 1770. Prof. Mexico; writer on Aztec language.

Zenteno, JOSÉ IGNACIO, 1785-1847. Chilian general and minister of war, active against Spain.

Zeolite. Group of minerals, including a number of species,

ZEPHANIAH-ZIETRISIKITE

essentially hydrous silicates with aluminium and an alkali or alkaline element as basic components, agreeing closely with each other in type of chemical composition, but varying widely in color, hardness, and crystalline form. They are minerals of secondary origin, in some respects analogous to the feldspars. When heated before the blowpipe, they easily part with their water, often with intumescence and an appearance of boiling. The word signifies boiling-stone.

Zephaniah, Hebrew prophet, author of 36th O. T. book, ab.625 B.C., directed against the corruptions of Judah. Zepharovich, VICTOR VON, 1830-1890. Prof. Cracow and Prague; writer on crystallography; connected with Austrian

surveys.

Zephyrinus. Bp. of Rome 199-218.

Zephyrus. West wind, personified in Greek mythology. Zequeira, MANUEL DE, ab.1760-1846. Cuban poet. Zerafshan. River of Bokhara, useful for irrigation, but lost in the sand near Samarkand.

Zermatt. Village in the canton of Valais, Switzerland, near the upper end of the Visp valley, 25 m. s.s. w. of Visp. It is a great tourist resort and center of Alpinists; starting-point for the ascent of the Matterhorn. The railway from Visp to

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Zeugobranchiata. Suborder of Gastropoda, including forms having paired bipennate gills, and paired kidneys, of which the left one is rudimentary. The heart has two auricles; the rectum perforates the ventricle. The lip of aperture of shell is cleft, as is the anterior border of the mantle. The radula has in each transverse row of teeth a great number of lateral hooked plates, arranged in a fanlike manner. There is no proboscis or siphon. The animals are herbivorous; the shell resembles that of the Patellida. Fissurella and Haliotis are examples. Some place the group as a subdivision of RHIPIDOGLOSSA (q.v.). Zeuner, CHARLES, 1795-1857. German-American organist, composer, and compiler in Boston and Philadelphia. Zeus. Chief of Greek deities; son of Cronos and Rhea; father of many mythological personages; later identified with,

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Z., opened 1891, combines adhesive (max. gradient 45:1,000) and rack and pinion (125:1,000) systems. The graves of many of the victims of mountaineering are here. Altitude 5,315 ft., pop. ab. 2,000.

Zero. (A) Absence of magnitude; absolute nothing. (B) Less than any assignable quantity; beginning of magnitude; treated algebraically as a positive even integer; used as a limit in higher analysis. Zero co-ordinates of position indicate coincidence with fixed elements of reference. The zero angle denotes sameness of direction. Zero as a term does not affect the result: as a factor, it gives a zero-product: as a dividend with a finite divisor, it gives a zero-quotient, or, by the theory of limits, as the dividend approaches the zero, the ratio approaches zero as a limit. As a divisor with a finite dividend. zero is said to give an infinite quotient, or, by the theory of limits, as the divisor approaches zero, the ratio increases without limit. The ratio, zero divided by zero, &, is indeterminate. See ABSOLUTE ZERO.

Zero-Axial. Determinant whose principal diagonal has only zero terms.

Zerotin, KARL VON. 1564-1636. Gov. of Moravia 1608-15; protector of the Unitas Fratrum or Bohemian Brethren; exiled 1627.

Zerrahn, CARL, b. 1826 in Germany. Director Boston Handel and Hadyn Society since 1854; conductor at many concerts and festivals.

Zerubbabel. Leader of the Jews who returned from Babylon 536 B.C. to rebuild Jerusalem and the Temple.

Zeruiah. Elder half-sister of King David, and mother of his generals, Joab, Abishai, and Asahel.

Zesen, PHILIPP VON, 1619-1689. German poet and novelist Torments of Love.

Zetland. See SHETLAND.

Zetterstedt, JOHAN WILHELM, 1785-1874. Swedish botanist and zoologist; prof. Lund 1839-53. Diptera Scandinavia, 14 vols., 1842-60.

Zeugita. See ALLOPOLA.

Zeuglodon. Huge fossil cetacean found in the Eocene beds of several Gulf States. Its vertebræ are so abundant in places that they are piled up in the fields to clear the land. Zeuglodontia. See ARCHEOCETI.

Bust of Zeus, by Otricoli.

or replaced by, the Roman Jupiter. In Homeric mythology, Z. is king of gods and men, the supreme ruler, the sovereign source of law and order, the fountain of justice, and the final arbiter of disputes.

Zeuxippus. Successor of Enesidemus in the leadership of the revival of Pyrrhonian skepticism.

Zeuxis, 5th cent. B.C. Greek painter of great fame, rivaled only by Parrhasius; at Athens ab.420 B.C. Helen, Hercules and Zeus were among his most noted subjects. Zhitomir. See JITOMIR.

Zhukofsky, VASILII, 1783-1852. Russian lyric poet and translator.

Zidon. See SIDON and TYRE.

Ziegenbalg, BARTHOLOMEW, 1683-1719. German missionary at Tranquebar, s. India, from 1706; tr. N. T. into Tamil 1711. Ziegler, ERNST, b. 1849. Prof. Zurich 1881, Tübingen 1882; writer on pathology.

Ziegler, HEINRICH, b. 1841. German theologian. Irenæus, 1868-71; Christus, 1891.

Ziem, FELIX, b.1821. French painter, distinguished for views of Venice: at his best, which is infrequent, a magnificent colorist.

Ziemer, HERMANN, b.1845. German writer on syntax. Zierikzee. Town of Schouwen, Zealand; memorably though vainly defended against Spaniards 1576. Pop., 1890, 7,060.

Zieten, or Ziethen, HANS JOACHIM VON, 1699-1786. Prussian general of cavalry 1760, distinguished in the wars of Frederick II. against Austria.

Zietrisikite. Natural hydrocarbon compound, occurring as a mineral in wax-like masses; in many of its properties allied to ozokerite.

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Ziggerat. Artificial hill intended for sacred uses in old Babylonia; usually constructed with seven platforms, but sometimes with two. There is no evidence that the different stories were painted in different colors, as has been asserted, or that the use was necessarily astronomical. It may be regarded simply as an attempt to reproduce a mountain. The Tower of Babel was unquestionably a ziggerat.

Zig-Zag. Molding peculiar to Norman style of architecture, of considerable variety.

Zigzag Riveting. Riveted joints where the rivets in parallel rows are placed alternating with each other, thus making a tight joint. See CHAIN RIVETING.

Zigzags. Approaches constructed from the parallels in siege operations to reach the covered way of the besieged position. Their general direction is along the capitals of the bastion or polygonal work to be attacked. Each branch is directed obliquely to the front, so as to pass to the front of any position which the enemy can occupy to enfilade them. They are constructed by the flying, full, or double-sap, under the direction of the engineer officers charged with the conduct of the siege. See SIEGE.

Ziller, TUISKON, 1817-1882. Prof. Leipzig 1864; writer on pedagogy and ethics.

Zillerthal. Tyrolese valley, n. of that of the Inn; 400 Protestants were expelled from it 1837.

Zilpah. Handmaid of Leah and inferior wife of Jacob; ancestress of the tribes of Issachar and Zebulun.

Zimb. Venomous dipterous insect found in Abyssinia, resembling and related to the TSETSE (q.v.).

Zimbabye, or ZIMBABWE. Remarkable ruins in British S. Africa, to the s.e. of Fort Victoria, in 20° 16' 30" S., and 31° 7' 30" E., at an altitude of 3,340 ft. The ruins evidently formed a garrison for the gold-producing race in remote antiquity, of whose work many traces have been found.

Zimisces, JOHN, 925-976. Byzantine Emperor 969-976. His abundant coins show the head or figure and titles of Christ, instead of his own.

Zimmerman, JOHANN GEORG VON, 1728-1795. Swiss physician and author of vast repute in his day. His Solitude, 1755, was widely read.

Zin. N.e. part of the wilderness in which the Israelites wandered in coming out of Egypt.

Zinc. Zn. Element. At.wt. 65.3, valence II.; mentioned first by Basil Valentine, and Paracelsus, 15th century. White metal with a bluish-gray tint, malleable between 100° and 150° C., but crystalline and somewhat brittle below 100°, and brittle as glass above 200° C. Sp.gr., cast 6.9, rolled or hammered 7.2 to 7.3; mpt. 424° C.; bpt. ab. 1,000 C.; sp.ht. 0.0956 (0 to 100° C.). Heated to bright redness, it takes fire in the air and burns with a greenish-blue light to white flakes of oxide (Philosopher's wool). When exposed to moist air it becomes coated with a basic carbonate. It is soluble in the common acids and in sodium and potassium hydroxides.

Zinc, METALLURGY OF. The principal zinc ores are as follows: Zincblende or sphalerite, a zinc sulphide, ZnS, containing 67 per cent of zinc when pure, but carrying up to 18 per cent of iron and to 3 of cadmium. It is found in many countries, and very abundantly in Mo. Zincspar or smithsonite is a carbonate, ZnCO,, carrying 52 per cent of zinc. Calamine is a hydrous silicate, 2ZnO.SiO,H,O, occurring in white, knuckle-like bunches of crystals. Similar-looking smithsonite is often erroneously called calamine. Willemite is anhydrous silicate, 2ZnO.SiO,. Zincite is red oxide, ZnO, its color being due to iron and manganese. Franklinite is a black mineral like magnetic iron ore, and consists of oxides of zinc, iron and manganese. The latter three minerals are found abundantly only in n. N. J. These minerals all have value as ores of zinc; they occur in many forms and under many diverse geological conditions. There are also other minerals, less common, in which zinc is an essential constituent.

The principle on which the smelting of zinc ores is based is the reduction of the oxide ore by carbon in a closed retort, and condensing the zinc vapors driven off. If the ore is a sulphide ore, it must first be roasted to oxide as a preliminary to reduction. This volatilization of the zinc is practically inevitable, because, under atmospheric pressure, zinc boils at a temperature less than is required for the reduction of its oxide. The temperature of reduction is a bright reddish yellow, ab. 1,150° C., while zinc boils at ab. 1,000° C.

When a mixture of oxidized zinc ore with granulated carbon is heated, it is probably not the carbon which directly abstracts oxygen from the ore, since such action could take place only at the few points of contact of carbon and ore; but the small amount of air always present forms with the carbon carbonic oxide, which reduces the ore over all its surface, forming car

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bonic acid gas. The latter is reduced back by carbon to carbonic oxide, and thus the cycle continues.

The roasting of sulphide ore (black-jack ore) to oxide requires considerable care. The finely-divided ore is heated slowly to bright redness in a roasting furnace, with excess of air admitted, being continually turned over. At a low heat, the sulphide forms largely sulphate, ZnSO4, which at a higher heat splits up into ZnO and SO,, the former being then suitable for reduction.

The original form of apparatus for reducing zinc ores is no longer in use. It was called the English process, and consisted of crucibles in which the charge was heated, with tightly fitting covers, and a pipe passing through a hole in the bottom and reaching above the charge and below the crucible into a clear space below the fire; the lower part of the tube serving as a condenser for the zinc vapors driven off the charge, whose only outlet was through the pipe. The melted metal condensed in the tube trickled down into pots set beneath. The capacity of the crucibles was so small, and the consumption of fuel so great, that the process could not compete with the muffle and retort furnaces.

In Belgium, cylindrical or oval retorts are used, placed ab. 100 in a furnace, as shown in Fig. 1, where a is the charge in

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the retort; b the condenser, in the hollow of which the liquid zinc accumulates; c the prolong in which zinc vapor is still further caught as a blue powder. Only ab. 20 to 30 lbs. of ore is treated at once in a muffle, the operation requiring 10 to 12 hours. Usually only three-quarters to four-fifths of the metal in the ore is extracted, the cost of working being ab. two and a half cents per lb. of zinc. The price paid for the ore averages one cent per lb. of zinc contained. With the older furnaces, fired by coal, the fuel consumed was a considerable item of expense; the modern furnaces are longer and fired by gas, thus rapid destruction of the muffles. effecting considerable economy in fuel, as well as causing a less

In Silesia the muffles are several times as large, and are called retorts. In Fig. 2 is shown the retort A, the condenser a, and

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Fig 2-Silesian Zinc-Furnace; transverse section.

their situation in the furnace. Each furnace contains ab. 24 of these retorts, each taking 60 lbs. of calcined ore, with carbon, skimmings of metal, etc. The operation takes ab. 24 hours; gas firing is used in all the recently-constructed furnaces.

The zine made in these furnaces is usually pure enough to go at once to the market. If a greater degree of purity is needed. the metal may be re-distilled, but a cheaper method is to melt it in a large pot and allow it to cool quietly and slowly. Lead sinks to the bottom and accumulates, while iron combined with some zinc falls to the bottom as a sandy residue; the purer zinc is ladled from the surface.

In Europe, Silesia and Belgium have long been large producers of zinc, and zinc ores are abundant in Italy and in Spain.

ZINC-ZIRCONIUM

The U. S. now ranks third in the list of zinc-producing countries, extensive deposits of ores being found in n. N. J., e. Pa., Va., s. w. Wis.. Mo., and other States. In 1897 the product of zinc in the U. S. was, in short tons, East and South, 9.673; Ill. and Ind., 38,616; Kan. and Mo., 51,814; total, 100, 103; ab. one-fourth the product of the world.

Commercial zinc (sometimes called spelter), usually contains lead, cadmium and iron, while tin, copper, arsenic, sulphur and carbon may be present in traces; it averages 98 to 99.5 per cent of zinc. Its market price is 4 cts. per lb.; re-distilled zinc commands 6 cts.

Zinc has been known as a commercial metal only since 1805; but it has many and important uses. Sheet zinc has many applications, while the metal is cast into art-castings and battery plates. The process of coating iron or steel with zinc by first cleaning and then dipping into the melted metal, the process erroneously called galvanizing, consumes a large proportion of the zinc made.

In alloys, the most important is brass, which is red brass when containing 3 of copper to 1 of zinc, and yellow brass with 2 of copper to 1 of zinc. Before zinc itself was known, brass was made by reducing together a mixture of zinc and copper ores; but now it is made entirely by melting the zinc into the copper. See BRASS and COPPER, METALLURGY OF.

Zinc, STRENGTH OF. Spelter zinc has a compressive ultimate strength of ab. 40,000 lbs. per sq. inch.

Zincates. Zn,(OH), (ONa),.17H,O; (2Zn(OH)(ONa).7H,O. Zinc hydroxide is soluble in alkaline hydroxides; from these solutions crystallized salts have been obtained, which have been called zincates.

Zincblende. See SPHALERITE.

Zinc Bloom. Hydrous zinc carbonate formed by chemical change of zinc ores; found in considerable quantity in some Spanish mines.

Zinc Bromide. ZnBr,. White soluble needles, melting to a bright yellow liquid; made by treating heated zinc with bromine.

Zinc Carbonate. Its composition varies according to condition. When zinc sulphate is precipitated with sodium carbonate, the basic salt Zn(OH),.ZnCO,.ZnO. is formed. It occurs in nature as SMITHSONITE (q.v.).

Zinc Chlorate. Zn(CIO),+6H2O. Hygroscopic soluble crystalline substance with an herb-like odor; mpt. 60° C.; made by treating the carbonate with chloric acid and evaporating. Zinc Chloride. ZnCl2. White, deliquescent substance, volatile at 680° C.; made by dissolving zinc in hydrochloric acid. It forms double salts with the alkaline chlorides.

Zinc Cyanide. Zn(CN),. Lustrous orthorhombic prisms, or amorphous powder, soluble in alkalies; made by treating the acetate with hydrocyanic acid.

Zinc Dust. Mixture of the metal and the oxide, obtained in the reduction of zinc ores, or by pulverizing the metal at a temperature just below its melting point. It is used as a reducing agent in chemistry.

Zinc Ethyl. Zn:(C,H,),. Zinc ethide; combination of the ethyl radical with zinc; prepared by the action of ethyl iodide upon zinc; liquid, bpt. 118° C., which takes fire with explosive violence if brought in contact with the air.

Zinc Fluoride. ZuF,. Soluble needles, sp.gr. 4.84; made by treating the metal or oxide with hydrofluoric acid.

Zinc Hydroxide. Zn(OH),. White, amorphous, insoluble powder, made by adding a soluble hydroxide to a soluble zinc salt; soluble in excess of the precipitant.

Zincing of Metals. See GALVANIZING.

Zinc Iodide. ZnI,. Octahedra, or cubes modified by octahedra. They decompose on heating, and are made by heating zinc with iodine.

Zincite. ZnO. Natural zinc oxide, occurring in n. N. J. as a red mineral, whose powder is orange-yellow in color; red zinc ore.

Zinc Methyl. Zn:(CH3)2. Zinc methide. See ZINC ETHYL, to which it corresponds in every respect.

Zine Nitrate. Zn(NO),+6H,O. Clear, four-sided columns; mpt. 36.4° C., bpt. 131° C.; made by dissolving zinc in nitric acid.

Zine Nitrite. Zn(NO)+3H,O. Hygroscopic crystals, decomposing at 100° C.; made by treating zinc sulphate with barium nitrite in solution.

Zinc Oxide. ZnO. Flores zinci, Zinc White, Philosopher's Wool. White powder, turning yellow when heated; made by burning zinc or igniting the carbonate; used extensively as a constituent of white paint, and for complexion powders. It is made on a large scale by mixing pulverized blende, freed from sulphur by roasting, or other zinc ores, with fine anthra

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cite or coke, and burning the mixture in a furnace. The zinc is reduced to the metallic state and free access of air converts it into the oxide. The light zinc oxide with the gases are drawn through a series of chambers, where the heavier impurities are deposited and the gases with the oxide are forced into cotton bags, the gases passing through the tissue, the oxide being retained. This is ground with linseed oil for a white pigment. It does not cover as well as white lead and, not forming so strong a combination with the oil, does not withstand the weather as long. It is not blackened by sulphur vapors from burning coal or illuminating gas. 1897, 26,275 short tons were produced in the U.S.

In

Zinc Phosphate. Zn, (PO),. Prisms, sp.gr. 3.99, melting at a red heat; made by boiling the oxide or carbonate in phosphoric acid.

Zinc Sulphate, ZINC VITRIOL, or WHITE VITRIOL. ZnSO, +7H,O. Transparent, rhombic prisms, made by roasting zinc blende and extracting with water; used in the preparation of cotton-prints and in medicine; found in nature as the mineral GOSLARITE (q.v.).

Zinc Sulphide. ZnS. Found in nature as SPHALERITE and BLENDE (q.v.). Artificially it is made by adding a soluble sulphide to a soluble zinc salt. It is a white, amorphous substance.

Zinc White. See ZINC OXIDE.

Zingarelli, NICOLA ANTONIO, 1752-1837. Italian composer of 31 operas, 4 oratorios, over 150 masses, and many motets, hymns, etc.

Zingerle, IGNAZ VINCENZ, b.1825. Tyrolese poet and historical writer, prof. Innsbruck 1859.

Zinkenite, or ZINCKENITE. PbSb,S4. Rare mineral compound of lead, sulphur, and antimony, first found at an antimony mine in the Harz Mountains.

Zintgraff, EUGEN, 1858-1897. German traveler in Africa. Zinzendorf, NICHOLAS LUDWIG, GRAF VON, 1700-1760. Protector of Moravian ex les at Herrnhut 1722; reviver of the

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Zircon. ZrSiO.. Zirconium silicate, found as a rare mineral in several widely separated parts of the world, as Ceylon, Australia, N. C., and Norway, usually as an accessory ingredient in crystalline rocks. When transparent, colored and brilhyacinth. The duller opaque varieties are utilized in the prepliant in luster, it has value as a gem-stone under the name of aration of the highly refractory earth, zirconia.

Zirconia. See ZIRCONIUM OXIDE.

Zirconium. Zr. At.wt. 90.6, sp.gr. 4.15, sp.ht. .066, valence IV. Discovered by Berzelius 1824; rare metal, obtained

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by heating potassium fluozirconate with aluminium, as an amorphous black powder or in crystalline metallic leaflets. occurs in nature chiefly as zircon, ZrSiO..

Zirconium Bromide. ZrBr4. White, crystalline powder, decomposed by water; made like the chloride.

Zirconium Chloride. ZrCl. White substance, fuming in the air; decomposed by water; made by treating a heated mixture of the oxide and carbon with chlorine. Zirconium Fluoride. ZrFl.. Colorless, translucent crystals, made by heating a mixture of fluorspar and zircon in hydrochloric acid gas.

Zirconium Hydroxide. Zr(OH),. White, amorphous powder, precipitated from acid solutions of zirconium by ammonium hydroxide; decomposed by heat, yielding zirconium oxide.

Zirconium Oxide. ZrO,. Zirconia. Amorphous powder, or quadratic prisms, obtained by igniting the metal or heating the hydroxide.

Zirconium Silicate. See ZIRCON.

Zirconium Sulphate. Zr(SO,),. White mass, soluble in water, decomposing on heating; made by treating the hydroxide with sulphuric acid.

Zirknitz, LAKE OF. In Carniola, Austria. In August, the water sometimes disappears long enough to raise a crop of hay on the bottom, being connected underground with the river Laibach, and the caves of Adelsberg. Length 6 m., breadth 3 m., depth 15-50 ft., alt. 1805 ft.

Z Iron. Bar whose cross-section resembles the letter Z, really like this ; rolled of wrought-iron and steel, and used for making posts and compression members in bridges.

Ziska, JOHN, 1360-1424. Bohemian officer, distinguished at Tannenberg 1410, and Agincourt 1415; leader of the Hussites from 1419; one-eyed, and blind from 1421; victor in 13 battles and 100 skirmishes; only once defeated. At Deutsch-brod, Jan. 18, 1422, he routed the Emperor Sigismund, who had violated his safe-conduct and given Huss to the flames.

Zither. Musical instrument, extremely popular in the Tyrol and other mountainous sections of Germany and Austria. It consists of a flat sound-box strung with from 36 to 42 strings, all but five of which are of gut or silk. The five are of metal, and

There are three groups: Sclerobasica (Antipatharia), Malacodermata (Actinaria), and Sclerodermata (Madreporaria). Zoanthidæ. Family of Zoantharia, Malacodermata, or Polyps, closely related to those that secrete coral, but free, having no hard, rock-like support; further characterized by including compound individuals, each consisting of many polyps united by a common cœnosarc. The walls of these polyps are often strengthened by a crust containing grains of sand or spicules.

Zoar, or BELA. One of the Cities of the Plain, s.e. of Dead Sea; spared at Lot's prayer. Gen. xix. 20-23.

Zobah. Ancient kingdom of Syria, at war with Israel. Zöckler, OTTO, D.D., b. 1833. Prof. Greifswald 1866; commentator. Cross of Christ, 1875, tr. 1877.

Zodiac. Zone of the celestial sphere, 16° in breadth, 8° each side of the ecliptic. It is divided into twelve signs of 30° each, beginning with the vernal equinox, as follows:

Aries Y Taurus 8 Gemini II Cancer Leo S

Virgo m

Libra Scorpio m Sagittarius 1 Capricornuss Aquarius Pisces 2

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are extended over a finger-board fretted chromatically. Upon this board the tones are formed by the fingers of the left hand; the melody is plucked by means of a ring or plectrum fastened to the thumb of the right hand, while the harmony is supplied by the fingers, as in the case of a harp.

Zittau. Town in s.e. Saxony, on a lignite deposit of 20 sq. m. It has manufactures of linen and cotton goods, dye and bleaching works, iron-smelting and glass works; also mineral springs. It was burned in the Austrian bombardment 1757. Pop., 1890, 25,400.

Zittel, CARL ALFRED VON, b. 1839. Prof. Munich 1866; author of an extensive handbook of Paleontology.

Znaim. Town of Moravia: scene of a French victory July 11, 1809. An armistice was concluded the next day. Pop., 1890, 14,515.

Zoan, or TANIS. Former capital of Egypt under the Hyksos kings and in 19th dynasty; in the Delta; often mentioned in O. T.; destroyed 174. Its remains were explored by Petrie

1883-84.

Zoantharia (HEXACTINIA). Division of Anthozoa, including coral polyps or polyp-stocks with tentacles in concentric circles and with the mesenteric septa in multiples of six. This group includes the most common corals. The anatomy of the soft parts is similar to that in the Sea-Anemone (Actinia).

[blocks in formation]

during Feb., March and April; supposed to be caused by the reflection of the sun's rays by meteoric matter in the vicinity of the sun.

Zoëa. Earliest larval stage of the Lobster and Crab. (The nauplius and other early stages represented by free larvæ in lower Crustacea are in Lobsters and Crabs passed through within the egg-shell.) It has a cephalothorax provided with three long spines, and a six-jointed abdomen without appendages. The only locomotor appendages present are those that represent the first two pairs of maxilipedes of the adult.

Zoecium. 1. Chamber or cell in which the polypide of a Polyzoön is contained. 2. Equivalent of zoöid.

Zoega, JOHANN GEORG, 1755-1809. Danish numismatist. antiquarian, and Orientalist, resident at Rome; cataloguer of Coptic MSS.

Zoepffel, RICHARD OTTO, D.D., 1843-1891. Prof. Strasburg 1872; ed., with H. J. Holtzmann, Lexikon fur Theologie, 1882-91.

Zoetrope. Optical toy in which a succession of figures in different attitudes are made to appear like a single one in motion. Two forms exist. In one the figures are arranged

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