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able lustre. It is hard, and not easily cut with solutions of pure alkalies; and a porwith a knife. The specific gravity is tion of the oxide is retained in solution. nearly 7.2 The ores of zinc are cala. It is oxydized when mixed with nitre, mine and blende. See CalamINARIS. Ca. and projected into a red-hot crucible. In lamine is an oxide, frequently with a por- this case a violent detonation ensues. tion of carbonic acid; blende is a sulphu.

Zinc combines with almost all the me. ret, containing also some iron, and other

tals, and some of its alloys are of great extraneous matters. The ores of zinc are found in many countries, and in a number

importance. It may be united to gold in of mines in this country. The metal is

any proportion by fusion. The alloy is obtained from the ore by distillation.

the whiter and the more brittle, the Zinc is melted by a moderate heat, and

a greater quantity of zinc it contains. An the fused mass, on cooling, forms regular

alloy, consisting of equal parts of these crystals. Though scarcely altered by ex.

metals, is very hard and white, receives a posure to the air at a low temperature, it has therefore been proposed as very

fine polish, and does not tarnish readily. yet it is rapidly oxydized by one amount. ing to ignition. When kept in a degree

proper for the specula of telescopes.

One part of zinc is said to destroy the of heat barely sufficient for its fusion, zinc becomes covered with a grey oxide. But

ductility of one hundred parts of gold. when thrown into a crucible, or deep

Platinum combines very readily with zinc.

The alloy is brittle, pretty hard, very earthen pot, heated to whiteness, it sud. denly inflames, burns with a beautiful

fusible, of a bluish-white colour, and not

so clear as that of zinc. The alloy of white flame, and a white and light oxide

silver and zinc is easily produced by fu. sublimes, having a considerable resemblance to carded wool This oxide, how

sion. It is brittle, and has not been ap

plied to any use. Zinc may be combined ever, when once deposited, is no longer volatile ; but if exposed to a violent heat,

with mercury, either by triturating the runs into glass. Zinc readily dissolves in

two metals together, or by dropping mer. sulphuric, nitric, and muriatic acids. With

cury into melted zinc. This amalgam is

solid. It crystallizes when melted, and nitric acid, it yields nitrous gas, if the acid be concentrated; or nitrous oxide,

cooled slowly into lamellated hexagonal

figures with cavities between them. They if diluted. Sulphuric and muriatic acids,

are composed of one part of zinc, and two diluted with water, evolve, during their

and a half of mercury. It is used to rub action on this metal, hydrogen gas; and

on electrical machines, in order to excite the gas, when obtained, holds in combi. nation a portion of the metal. A stream

electricity. of it has been found, if recently prepared, Zinc combines readily with copper, and to occasion the fusion of the platina wire, forms one of the most useful of all the me. though the pure gas is destitute of this tallic alloys. The metals are usually comproperty. This hydrogen gas, holding bined together by stratifying plates of zinc in solution, may also be obtained by copper, and a native oxide of zinc coma process of Vanquelin. A mixture of bined with carbonic acid, called calamine, the ore of zinc, called blende or calamine, and applying heat. When the zinc dnes with charcoal, is to be put into a porce. not exceed a fourth part of the copper, lain tube, wbich is to be placed horizon. the alloy is known by the name of brass. tally in a furnace, and, when red-hot, the It is of a beautiful yellow colour, more vapour of water is to be driven over it. fusible than copper, and not so apt to tarThe gas that is produced, however, is a nish. It is malleable, and so ductile, that mixture of carbonic acid, carburetted hy. it may be drawn out into wire. Ils density drogen, and hydro-zincic gas. The zinc is greater than the mean. It ought to be is deposited on the surface of the water, by calculation 7.6, but it actually is 8.4 by which this gas is confined; but, if nearly, so that its density is increased by burned when recently prepared, the gas about one-tenth. When the alloy contains exhibits, in consequence of this impreg- three parts of zinc and four of copper, it nation, a blue Alame. The solution of assumes a colour nearly the same with zinc in sulpburic acid shoois into regular gold, but it is not so malleable as brass. : crystals. This salt is readily soluble, and it is then called pinchbeck, prince's me. its solution is not precipitated by any tal, or Prince Rupert's metal. Brass was other metal. The muriate of zinc yields, known, and very much valued by the an. when evaporated, an extract of thick cients. They used an ore of zinc to form consistence, having the viscidity of bird- it, which they called cadmia. Dr. Wattime. Zinc is oxydized also, when boiled son has proved that it was to brass that

they gave the name of orichalcum. Their none; corolla glume two-valved, awnless, æs was copper, or rather bronze.

mixed with the females; female, calyx It is very difficult to form an alloy of none ; corolla glume two-valved, cowled, iron and zinc. Malouin has shown that awned; style two-parted; seed one, clothzinc may be used instead of tin to cover ed with the plaited corolla. There are iron plates, a proof that there is an affi- two species; viz. Z. aquatica, and Z ternity between the two metals. Tin and restris. zinc may be easily combined by fusion. ZIZIPHORA, in botany, a genus of the The alloy is much harder than zinc, and Diandria Monogynia class and order. scarcely less ductile. This alloy is often Natural order of Verticillatæ. Labiatæ, the principal ingredient in the compound Jussieu. Essential character; calyx fili. called pewter.

form ; corolla ringent, with the upper lip ZINNIA, in botany, so named in ho- bent back and entire ; seeds four. There nour of JobnGodofr. Zinn, a genus of the are four species. Syngenesia Polygamia Superflua class and ZODIAC, in astronomy, a broad circle, order. Natural order of Compositæ Op whose middle is the ecliptic, and its ex. positifoliæ. Corymbiferæ, Jussieu. Es. tremes, two circles, parallel thereto, at sential character: calyx ovate, cylindri. such a distance from it, as to bound or cal, imbricate ; forets of the ray five, comprehend the excursions of the sun permanent, entire ; seed down, with two and planets. erect awns; receptacle chaffy. There The sun never deviates from the midare five species.

dle of the zodiac, i. e. from the ecliptic, ZIRCON, in mineralogy, the name of a but the planets all do more or less. Their genus containing two species, viz. hya. greatest deviations, called latitudes, are cinth and zircon: the former will be found the measure of the breadth of the zo. in the alphabetical arrangement; we diac, which is broader or narrower, as the therefore proceed to the species zircon, greatest latitude of the planets is made the chief colour of which is grey; but it more or less; accordingly some make it occurs through all the varieties of green, sixteen, some eighteen, and some twenty blue, red, yellow, and brown. It is found degrees broad. The zodiac, cutting the coinmonly in roundish angular pieces, equator obliquely, makes an angle therewhich have almost always rounded angles witb of about 231°, which is what we call and edges. It is likewise crystallized. the obliquity of the zodiac, and is the Specific gravity about 4.6. The constitu- sun's greatest declination. ent parts are, according to Klaproth,

The zodiac is divided into twelve porZirconia . . . . . 69.0 tions, called signs, and those divisions or Silica . . . . . . 26.5 signs are denominated from the constelOxide of iron .. . 0.5 lations which anciently possessed each Loss . . . . . . 4.0 part : but the zodiac being immoveable,

and the stars having a motion from west 100.0 to east, those constellations no longer

correspond to their proper signs, whence

arises what we call the precession of the It is infusible without addition by the blow-pipe; with borax it forms a colour

ZOEGEA, in botany, a genus of the less glass. It is found in Ceylon, in the sand of a river, accompanied by crystals

Syngenesia Polygamia Frustranea class of spinelle, tourmaline, ceylanite. It is

and order. Natural order of Compositx

Capitatæ. Cinarucephalæ, Jussieu. Esalso found in America ; Mr. Solomon Conrad of Pbiladelpbia discovered it near

sential character; calyx imbricate ; corol

la of the ray ligulate; down bristle-shap. Trenton, New Jersey. It is frequently

ed; receptacle bristly. cut as a precious stone, and employed for

There is but one various purposes, particularly as an orna

species, viz. Z. leptaurea, a native of the

Levant. ment in mourning-dress. When it is cut it exhibits, though in a very faint degree,

ZOISITE, in mineralogy, is of a greythe play of colours of the diamond. Some

ish colour. It occurs massive, and in of the varieties are frequently used by crystals, which are imbedded. It occurs watchmakers in jewelling watches. in primitive mountains, principally in

ZIZANIA, in botany, a genus of the quartz with mica. This fossil is placed Monoecia Hexandria class and order. Na between the axinite and pistazite, and tural order of Gramina. Gramineæ, Jus. connects both species together. sieu. Essential character: male, calyx ZONE, in geography and astronomy,

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a division of the terraqueous globe, with the air into their lungs, but their blood is respect to the different degrees of heat likewise cold, and in both fishes and amfound in the different parts thereof. A phibia the heart has only two regular ca. zone is the fifth part of the surface of the vities, while that of animals with warm earth, contained between two parallels. blood has four. Of the latter, the ovipaThe zones are denominated torrid, frigid, rous are birds, and are generally covered and temperate. The torrid zone is a band with feathers; the viparous are either surrounding the terraqueous globe, and quadrupeds or cetaceous animals, and are terminated by the two tropics. Its furnished with organs for suckling their breadth is 46° 58'. The equator running young. See PaYSJOLOGY. through the middle of it, divides it into Each of the classes of animals is subtwo equal parts, each containing 23° 29'. divided by Linnæus into different orders: The ancients imagined the torrid zone for a scientific account of these orders, uninhabitable. The temperate zones are and also of the classes from whence they two bands, environing the globe, and con- spring, the reader is referred to the sevetained between the tropics and the polar ral heads of the Dictionary in the alphacircles: the breadth of each is 43° 2'. betical order: and here we shall take a The frigid zones are segments of the sur. cursory view of the subject, in order to face of the earth, terminated, one by the give, in a short compass, a sort of outline antarctic, and the other by the arctic cir- of the science. cle. The breadth of each is 46° 58'.

The first class, denominated MammaZONITES, in natural history, a genus lia, from the female's suckling its young, of insects of the order Coleoptera: anten. comprehends all viviparous animals with næ testaceous; four feelers filiform ; jaw warm blood. These, with very few ex. entire, longer than the feelers; lip emar. ceptions, have teeth fixed in their jaw. ginate. There are eight species, found bones; and from the form and number of chiefly in warm countries.

these teeth the orders are distinguished, ZOOLOGY, constitutes that branch of except that of cetaceous fishes, which is natural history which relates to animals. known by the fins that are found in the Various methods of arrangement have, place of feet. The distinctions of the by different naturalists, been devised to teeth are somewhat minute, but they aprender this branch of study easy of com- pear to be connected with the mode of prehension, and familiar to the minds of life of the animal, and they are tolerably those who wish for a general view of ani- natural. The first order, Primates, conmated nature. We shall, in this article, tains man, monkeys, and bats: the second, give an outline of the Linnæan system, Bruta; among others, the elephant, the which has, in the various departments of rhinoceros, the ant-eater, and the orni. the British Encyclopedia, been adopted, thorynchus, an extraordinary quadruped, as most generally approved by philoso. lately discovered in New Holland, with a phers of all countries.

bill like a duck, and sometimes teeth inLinnæus divides the whole animal king. serted behind it: but there are some sus. dom into six classes, the characters of picions that the animal is oviparous. The which are taken from the internal struc- order Feræ contains the seal, the dog, the ture of the being treated of. It may be cat, the lion, the tiger, the weasel, and the observed, that a considerable portion of mole, most of them beasts of prey; the the bulk of animals is composed of tubu. opossum and the kangaroo also belong to lar vessels, which originate in a heart: this order, and the kangaroo feeds on ve. the heart propels through the arteries, getables, although its teeth are like those with the assistance of their own muscu. of carnivorous animals. The fourth orlar powers, either a colourless transpa- der, Glires, comprehends beavers, mice, rent fluid, or a red blood, into the extre. squirrels, and hares: the fifth, Pecora, mities of the veins; through which it camels, goats, sheep, and horned cattle. again returns to the origin of motion. The sixth order, Belluæ, contains the Insects and worms have their circulating horse, the hippopotamus, and the hog. fluids a little warmer than the surround. The cetaceous fishes, or whales, form the ing medium, and in general it is colour. seventh and last order; they reside in the less; but insects have legs furnished with water, enveloped in a thick clothing of joints, and worms have nothing but sim. fat, that is, of oily matter, deposited in ple tentacula at most, in place of legs. cells, which enables their blood to retain Fishes have cold red blood, which is ex. its temperature, notwithstanding the exposed to the air contained in water by ternal contact of a dense medium consi. means of their gills. Amphibia receive derably colder.

Birds are distinguished from quadru. cent, but others have fangs, by which they peds by their laying eggs; they are also instil a poisonous Auid into the wounds generally feathered, although some few that they make. In England, the viper is are rather hairy, and, instead of hands or the only venomous serpent; it is known fore-legs, they have wings. Their eggs by its dark brown colour, and by a stripe are covered by a calcareous shell; and of whitish spots running along its back : they consist of a white, or albumen, but to mankind its bite is seldom, if ever, whicb nourishes the chick during incuba- fatal. tion, and a yolk, which is so suspended The first three classes of animals have within it, as to preserve the side on which lungs, as we have already seen, for respi. the little rudiment of a chicken is situa. ration, and receive air by the mouth; ted continually uppermost, and next to those which have gills, and red blood, the mother that is sitting on it. The yolk are fishes, residing either in fresh or in is, in great measure, received into the salt water, or indifferently in both : their abdomen of the chicken a little before the eggs are involved in a membrane, and time of its being hatched, and serves for have no albumen. its support, like the milk of a quadruped, Of the six orders of fishes, four bare and like the cotyledons of young plants, regular gills, supported by little bones; until the system is become sufficiently and they are distinguished according to strong for extracting its own food out of the place of their ventral fins, into Apodes, the ordinary nutriment of the species. as the eel and lamprey : Jugulares, as the

Birds are divided, according to the cod: Thoracici, as the sole and perch: form of their bills, into six orders: Acci and Abdominales, as the salmon and pike: pitres; as eagles, vultures, and hawks. distinctions which appear to be perfectly Picæ; as crows, jackdaws, humming- artificial, although useful in a systematic birds, and parrots. Anseres; as ducks, arrangement. The two remaining orders swans, and gulls. Grallæ; as herons, are without bones in the gills, those of woodcocks, and ostriches. Gallinæ; as the one being soft, and of the other carti. peacocks, pheasants, turkies, and com- laginous or gristly. These are, the Bran. mon fowls. And, lastly, Passeres; com. chiostegi and Chondropterygii of Artedi, prehending sparrows, larks, swallows, which Linnæus, from a mistake, classed ihrushes, and doves. The amphibia are among the Amphibia. The sun fish, the in some respects very nearly allied to lump fish, the fishing frog, and the sea. birds; but their blood is little warmer than horse, are of the former; and the sturthe surrounding medium. Their respi. geon, the skate, and the shark of the lat. ration is not necessarily performed in a ter order. continual succession of alternations, since Insects derive their name from being the whole of their blood does not pass almost always divided, into a head, tho. through the lungs, and the circulation rox, and abdomen, with very slender inmay continue without interruption in tervening portions: although these diri. other parts, although it may be impeded sions do not exist in all insects. They in these organs for want of the motion of are usually oviparous; they respire, but respiration. They are very tenacious of not by the mouth; they have a number of Jife; it has been asserted on good autho. little orifices on each side of the abdomen, rity, that some of them have lived many by which the air is received into their years without food, inclosed in hollow ramified trachea; and if these are stoptrees, and even in the middle of stones: ped with oil, they are suffocated. Instead and they often retain vestiges of life some of bones, they have a hard integument or days after the loss of their hearts. Their shell. Their mouths are formed on coneggs are generally covered with a mem- structions extremely various, but gene. brane only. They have sometimes an in- rally very complicated: Fabricius has termediate stage of existence, in which all made these parts the basis of his classifitheir parts are not yet developed, as we cation ; but from their minuteness in most observe in the tadpole ; and in this re. species, the method is, in practice, insu. spect they resemble the class of insects. perably inconvenient : and the only way They are now universally considered as in which such characters can be rendered divided into two orders only: Reptilia; as really useful is, when they are employed the tortoise, the dragon, or Aying lizard, in the subdivisions of the genera, as deterthe frog, and the toad; all these have mined from more conspicuous distinctions. four feet; but the animals which belong Insects have most frequently jaws, and to the order Serpentes are without feet. often several pairs, but they are always Most of the serpentes are perfectly iono. so placed as to open laterally or horizontally. Sometimes, instead of jaws, they polype, imitating, by its extended arms, have a trunk or proboscis. In general the appearance of an imperfect flower. they pass through four stages of existence, The last order, Infusoria, is scarcely dis. the egg, the larva, or stage of growth, tinguished from the Intestina and Mollus. the pupa, or chrysalis, which is usually ca by any other character than the miin a state of torpor or complete inactivity, nuteness of the individuals belonging to and the imago, or perfect insect, in its it, and their spontaneous appearance in nuptial capacity. After the last change, animal and vegetable infusions, where we the insect most frequently takes no food can discover no traces of the manner in till its death.

which they are produced. The process The Linnæan orders of insects are, the by which their numbers are sometimes Coleoptera, with hard sheaths to their increased is no less astonishing than wings, generally called beetles, the Hem- their first production; for several of the iptera, of which the sheaths are of a softer genera often appear to divide, spontane. nature, and cross each other, as grasshop- ously, into two or more parts, which bepers, bugs, and plant lice; the Lepidop- come new and distinct animals, so that in tera, with dusty scales on their wings, as such a case the question respecting the butterflies and moths; the Neuroptera, as identity of an individual would be very the libellula, or dragon-fly, the may.fly, difficult to determine. The volvox, and and other insects with four transparent some of the vorticellæ, are remarkable wings, but without stings; the Hymenop for their continual rotatory motion, proba. tera, which have stings, either poisonous bly intended for the purpose of straining or not, as bees, wasps, and ichneumons; their food out of the water: while some the Diptera with two wings, as common other species of the vorticellæ resemble flies and gnats, which have halteres, or fungi or corallines in miniature. balancing rods, instead of the second pair ZOOPHYTA, in natural history, an or. of wings; and, lastly, the Aptera, without der of the class Vermes. Zoophyta are any wings, which form the seventh order, composite animals, bolding a medium be. comprehending crabs, lobsters, shrimps, tween animals and vegetables. Most of and prawns, for these are properly insects; them take root and grow up into stems, spiders,scorpions, mille pedes, centipedes, multiplying life in their branches and deci. mites, and monoculi. 'The Monoculus is duous buds, and in the transformation of a genus including the little active insects their animated branches or polypes, which found in pond-water, which are scarcely are endowed with spontaneous motion. visible to the naked eye, as well as the Plants, therefore, resemble zoophyta, but Molucca crab, which is the largest of all are destitute of animation and the power insects, being sometimes six feet long. of locomotion; and zoophyta are, as it Besides these, there are several genera of were, plants, but furnished with sensation apterousinsects, which are parasitical, and and the organs of spontaneous motion. infest the human race as well as other of these some are soft and naked, and animals.

others are covered with a hard shell: the The Vermes are the last and lowest of former are by some naturalists called animated beings, yet some of them are not zoophytes, and the latter are denominated deficient either in magnitude or in beau. lithophytes. There are fifteen genera, ty. The most natural division of vermes viz. is into five orders; the Intestina, as earthworms and ascarides, which are distin. Aleyonium

Madrepora guished by the want of moveable appen Antipathes

Mille pora dages, or tentacula, from the Mollusca, Cellepora

Pennatula such as the dew snail, the cuttle fish, the Corallina

Sertularia sea anemone, and the hydra, or fresh wa. Flustra

Spongia ter polype. The Testacea have shells of Gorgonia

Tubipora one or more pieces, and most of them in Hydra

Tubularia habit the sea, and are called shell fish, as Isis the limpet, the periwinkle, the snail, the muscle, the oyster, and the barnacle. The coral reefs that surround many The order Zoophyta contains corallines, islands, particularly those in the Indian sponges, and other compound animals, Archipelago and round New Holland, are united by a common habitation, which formed by various tribes of these animals, has the general appearance of a vegeta- particularly by the Cellepora, Isis, Madreble, although of animal origin; each of the pora, Millepora, and Tubipora. The ani. little inhabitants resembling a hydra, or inals form these corals with such rapidity,


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