much frequented by the merchants of Germany and France. It is seated on the Rhine, just above the junction of the Aar with that river. ZUTPHEN, a county of the United Provinces, in Guelderland; bounded on the N. by the Yssel, which separates it from Velaw, on the W. by Overyssel, on the E. by the bishopric of Munster, and on the S. by the duchy of Cleves.

ZUTPHEN, a strong and considerable town of Dutch Guelderland, capital of a county of the same name. It was taken, in 1672, by the French, who restored it in 1674. It is seated at the confluence of the Berkel and Yssel, nine miles S. by E. of Deventer, and 55 E. by S. of Amsterdam, Lon. 6. 0 E. Lat. 52. 10 N.

ZUYST, a village of Holland, five miles from Utrecht, It abounds in plantations and shady walks, and is greatly ornamented by the spacious buildings which count Zinzendorf appropriated to the fraternity of Hernhuthers or Moravians. The brethren are employed in various kinds of manufacture, and their workmanship far exceeds that of any other part of Holland; but the articles are proportionably dearer, Zuyst is much frequented in the summer months, by merchants who have no country seats of their own.

ZWICKAU, a town of Upper Saxony, in Misnia, on the frontiers of Voigtland, with a citadel, three churches, and a Latin school, in which is a good library, Here are manufactures of cloth and leather, and a trade in corn and beer, It is seated on the Mulda, 20 miles N.N.E. of Plauen, and 21 S. of Altenburg. Lon. 12. 28 E. Lat, 50, 42 N.

ZWINGERA, in botany, a genus of the class decandria, order monogynia. Calyx five-parted; petals five; filaments dilated and hairy at the base; capsules five, coriaceous, one-seeded, inserted on a fleshy receptacle, Que species; a Guiana shrub, eight feet high, with oblong, emarginate leaflets.

ZWOLL, a fortified town of Holland, in Overyssel, with three handsome suburbs. On the adjacent mountain of St. Agnes was formerly an Augustine convent, in which Thomas Kempis lived 71 years, and died in, 1471. A canal begins near this place, and extends to the river Yssel, which is defended by several forts. Zwoll is the most opulent town in the province, and stands on an eminence, on the river Aa, 14 miles N. of Deventer, and 31 S.W. of Coevorden. Lon. 6. 3 E. Lat, 59, 31 N.

ZYGENA, in the entomology of Fabricius, a tribe of the lepidopterous genus SPHINX, which see.

ZYGIA, in zoology, a genus of the class insecta, order coleoptera. Antennas monili form; feelers equal, filiform; lip elongated, membranaceous; jaw one-toothed. One speeies only, zygia oblonga, Head and shells

dull blue; thorax rounded, emarginate, punc tured, carinate; inhabits the East; middlesized, oblong, rufous.

ZYGETH, a strong town of Lower Hungary, capital of a county of the same name, with a citadel. It was besieged, in 1566, by Solyman II. emperor of the Turks, and taken three days after his death; but was afterward retaken by the Austrians. It is seated in a morass, made by the river Alma, 50 miles N.W, of Esseck. Lon. 18 58 E. Lat. 46, 17 N.

ZYGOMA. (from Cufos, a yoke; because it transmits the tendon of the temporal muscle like a yoke.) The cavity under the zygomatic process of the temporal bone and os malæ.

ZYGOMATIC PROCESS. An apophy, sis of the os jugale and another of the tempo ral bone are so called. See ANATOMY,

ZYGOMATIC SUTURE. Sutura zygoma, tica. The union of the zygomatic process of the temporal bone, to the cheek bone.

ZYGOPHYLLUM. Bean-caper. In bo tany, a genus of the class decandria, order monogynia. Calyx five-leaved; petals five; nectary ten-leaved, covering the germ; stamens seated on the germ; capsule five-celled. Fourteen species; natives of the East or West Indies, or the Cape. The following are culti vated,

1. Z. fabago. Common bean-caper. 2. Z sessifolium. African bean.caper. 3. Z. morgsana, Purslane-leaved Ethiopian bean-caper.

4. Z. spinosum. Thorny bean-caper. 5. Z. album. White Egyptian bean-caper. The first is herbaceous, and should be propagated by seeds; the rest are shrubs or undershrubs, and may be increased by seeds or cuttings.

ŽYMOSIMETER. (formed from fermentation, and rpov, measure.) An instru ment proposed by Swammerdam in his book De Respiratione, wherewith to measure the degree of fermentation occasioned by the mixture of different matters, and the degree of heat which those matters acquire in fermenting, as also the heat or temperament of the blood of animals.

ZYPÆUS (or Vanden Zyp, Francis), a learned man, born at Malines in 1580. His talents recommended him to the bishop of Ant, werp, who appointed him his secretary, canon, and archdeacon of his church. He died in 1650, aged 75. He wrote, 1. Analytica enarratio juris Pontificii novi. 2. Consultationes Canonicæ. 3. Notitia Juris Belgici. 4. De Jurisdictione Ecclesiastica & Civili.

ZYTHUS, (from tw, to ferment.) Beer; ale; any drink made of fermented corn.

ZYTOMIERZ, a town of Poland, in Volhinia, seated on the Ciecirief, 70 miles W. of Kiof, and 120 E, of Lucko. Lon. 29. 22 E, Lat. 50. 35 N,

slate. Blackish, of a compact slaty texture, giving a clear sound when struck, making a cinereous streak. Found in Sweden, Spain, and New Spain; of a shivery fracture, and a blackish, brown, grey, or reddish colour.

1. A. novacula. Novaculite. Whetstone. Turkey-stone. A little polished, shining within, subopake, hardish, greenish-grey, making a whitish mark. Found in schistose mountains, forming considerable layers, chiefly in the Levant, near Lauestein in Bareith, Siberia, and near Freyburg in Saxony. Fracture slaty, approaching to shivery: does not adhere to the tongue; receives an imperfect polish, hardens in the air and in oil, and when saturated with the latter makes an excellent whetstone.

2. A. tegularis. Proper argillite. Common argillaceous schist or slate. A little polished, rather hard, blueish-black, with a cinereous streak, with straight foliations.

This admits of many varieties: reddish, or brownish-red; purple; reddish-purple; greenish-grey. Chiefly used for the covering of houses. Found in many mountains of Britain, and in Europe generally.

3. A. nigrica. Soft black schist, or slate. Black chalk. Deep black, meagre, very soft, soiling the fingers, making a black streak, of an incurved slaty texture, breaking into discoid fragments or long splinters, becoming reddishgrey in the fire. This, and the two preceding, we have noticed more at length under the article SCHIST, to which the reader may turn for further particulars.

4. A. tabularis. Tabular schist or slate. A little polished, soft, greyish-black, making a whitish mark, with straight foliations. Found in Switzerland, Hungary, Franconia, and Saxony admits an imperfect polish, and is sometimes variegated with darker orbicular or oblong spots; when powdered effervesces in a very slight degree with nitric acid; is rather light, and is used for tables and slates.

6. A. compactissima. Compact thonschiefer or slate. Of a dull colour, very compact and solid, hardish, leaving a whitish streak. Found very rarely in China; black or brown, exteriorly glabrous and unequal, internally very compact.

7. A. atrata. Of a lamellar, slaty texture, very soft, making a whitish streak. Found in Lapland and various provinces of Sweden, meagre, blackish, brown, or yellowish; crackling when stirred in the fire, and running into a frothy kind of glass in a greater degree of heat, effervescing a little with nitric acid when powdered.

8. A. undulata. Black, of an undulately slaty texture. Found in Finland and Jemsia,, sometimes softer, and melting into porous slugs; sometimes a little harder, and melting into a solid glass.

9. A. bituminosa. Bituminous schist. Very soft, a little greasy, of a dull colour, shining when rubbed, leaving a black streak, of a straight slaty texture, breaking into discoid fragments, smoking or flaming in the fire, and at the same time becoming paler. Several vas. rieties. Found in Britain, Sweden, and Lusatia, forming large beds in stratified mountains, and strongly impregnated with bitumen and sulphur pyrite: colour generally black; a little glittering when broken.

10. A. kellas. Killas. Graywacke. Of a fibrous texture, slightly adhering to the tongue. Found in Cornwall, of a pale blueish-grey, red, or whitish-yellow colour, and often intersected with veins of copper or tin: surface undulated; fracture long, splintery, imperfectly slaty, lustre opake, silky.

Very

11. A. tessuralis. Rhombic slate. soft, somewhat ponderous, breaking into trapezoid fragments of a slaty texture. Found in Silesia, near Goldburg, and Neudorf, forming entire mountains, of a brown, pale yellow, or green colour.

DRACENA, in botany, a genus of the class hexandria, order monogynia; natural order sarmentaceæ. Calyxless; corol six-petalled, oblong, somewhat upright, equal, cohering by the claws; stamens six ; filaments inserted into the claws, subulate, thicker in the

middle, membranaceous at the base, shorter than the corol; anthers oblong, incuinbent; pistil an ovate germ, six-striated; style filiform, of the length of the stamens; stigma threecleft, obtuse; receptacle an ovate berry, six furrowed, three-celled; seeds solitary, ovateoblong, incurved at the tip. Five species, as follows.

1. D. draco. Dragon-tree.
2. D. ferrea. Purple dracæna.

3. D. ensifolia. Sword-leaved dracæna. 4. D. marginata. Olive-leaved dracæna. 5. D. borealis. Oval-leaved dracæna. Of these the third, dracæna ensifolia, or sword-leaved dracena, is most worthy of notice. It has a perennial root, horizontal, creeping, somewhat woody, odoriferous, and simple. The root-leaves heaped, thick, striated, shining, reflex, sword-shaped, a foot long. Scape three feet high, leafy at bottom, naked at top, round, slender, declining; the flowers terminal, subumbelled, of a blue or white colour.

It is the dianella ensifolia of the Hortus Kewensis; and under this name will be found in Nat. Hist. Pl. CLXXV.

ZIRCON, in mineralogy, an earth, so called from the metal of the same name. This earth was first discovered by Klaproth, and its leading properties have since been carefully investigated by Vauquelin. It is obtained from the metallic zircon, jargon, or hyacinth, by the following process. The mineral being very accurately pulverized is to be mixed with six times its weight of perfectly caustic potash dissolved in a little water. The mass being evaporated to dryness in a silver crucible is to be kept in a low red heat for two hours after this being allowed to cool, it will be found strongly adherent to the crucible, and must accordingly be covered by ten or twelve times its weight of water, to which must then be added a sufficiency of muriatic acid in order to supersaturate the alkali. By a gentle digestion the whole of the mass will be dissolved, and

the clear solution is to be evaporated slowly to dryness, stirring it about all the time to facilitate the separation of the silex. The residue of the evaporation is now to be digested with a moderate quantity of water slightly acidulated by muriatic acid, which will take up the zircon and oxyd of iron, leaving the silex behind. This evaporation and resolution in very dilute muriatic acid is to be repeated two or three times, that every particle of silex may be separated. To the muriatic solution is now to be added carbonat of ammonia, which will at first occasion an abundant precipitate, but by adding an excess of the alkali the whole of the zircon will be redissolved, and the oxyd of iron will fall to the bottom. The clear filtered liquor is to be boiled for two or three hours, by which the excess of ammonia will be driven off, and the zircon will be deposited in the state of carbonat, and in the form of a white powder. This powder being washed and properly dried is afterwards to be calcined, by which 4.3 per cent. of water and carbonic acid will be driven off, the remainder being pure zircon.

Calcined zircon is of a white colour, rough to the touch, insipid, and insoluble in water: specific gravity 4.3. After being exposed to an intense heat in a charcoal crucible it acquires a grey colour, a vitreous fracture, and is hard enough to give fire with steel. Nitric acid easily combines with it: muriatic acid takes it up from the carbonat, but does not touch it after it has been calcined. It is insoluble in water and alcohol, and by evaporation may be obtained in needle-shaped crystals. It is insoluble in the moist way by the fixed alkalies either caustic or carbonated, but is taken up by carbonated ammonia. In its affinities for the acids it is decidedly inferior to the alkalies, the alkaline earths, and even to alumine. Neither the earth nor its salts are made any use of.

T. Davison, Lombard-street, Whitefriars, London.