TUN
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Pliant brush-wood. The whole is ten feet in circumference, beingclosely wattled to the height of one foot, above which it is leftopen for the space of about eighteen inches; when it is againwattled to the height of eight or nine inches ; an opening, eighteeninches broad, being left at the lop, for the purpose of putting inturnips, or other provender. The staves, forming the skeleton ofthe machine above represented, are ten inches apart, so that twelvesheep may feed at one time in each tumbrel. Considerable ad-vantages are derived from this method of feeding sheep; as itgreatly reduces the expence of provender, which is thus preventedfrom being soiled with dung, or trodden under foot.
Tumbrel, is also a kind of carriage with two wheels, used inartillery, to carry the tools of pioneers, &c. or the money of anarmy.
TUMOR, in farriery. See Farriery .
TUN, a large vessel or cask, of an oblong form, biggest in‘lie middle, and diminishing towards two ends, girt about-withhoops, and used for stowing several kinds of merchandize forconvenience of carriage ; as brandy, oil, sugar, skins, hats, &c.
Tun is also tire name of a measure. A tun of wine is fourhogsheads; of timber, a square of forty solid feet; and of coals,twenty cwt.
Tun is also a certain weight whereby the burden of ships, &c.
are estimated.
TUNBRIDGE, a town of Kent , Oil a branch of the Medway.Lon. 0. 20 . E. Lat. 51. 14. N.
Tunbridge Wells, a town of Kent, 5, miles S. of Tunbridge ,hut in the same parish. In June, July, and August, it is muchfrequented for its mineral waters, which were discovered by Dud-ley lord North, in 1606.
TUNE. See Music, and Tone.
TUNGRl, an ancient nation of Germany , who lived on thehanks of the Maese, or of the Spaw.
TUNGSTATE, a salt formed by the union of tungstic acidwith different bases. See Tungstic Acid .
TUNGSTEN , one of the metals, discovered and ascertained,as distinct from earths, stones, and all other minerals, by the indus-try of modern chemists. “ There is a mineral, (says for. Thom-son) found in Sweden of an opaque white colour, and great weight,from which last circumstance it got the name of tungsten or pon-derous stone. Scheele analysed it in 1781, and found it was com-posed of lime and a peculiar earthy like substance, which he calledfrom its properties tungstic acid. Bergman conjectured that thebasis of this acid is a metal; and this conjecture was soon afterconfirmed by the experiments of Messrs. D’Elhuyart. Tungsten ,sometimes called by the German chemists Scheelium, is of a grey-ish white colour, and has a great deal of brilliancy. Itisoneofthe hardest of the metals; for Vauquelin and Hecht could scarcelymake any impression upon it with a file. It seems also to be brit-tle. Its specific gravity, according to the D Elhuyarts, is 17.6 :but this is doubtful, without farther experiments. It requires forfusion a temperature of at least 170° Wedg. It seems to have theProperty of crystallizing or cooling, like all the other metals; forthe imperfect button, procured by Vauquelin, contained a great"umber of small crystals. It is not attracted by the magnet.When heated in an open vessel it gradually absorbs oxygen, and>s converted into an oxide. Tuhgsten is capable of combiningwith two different proportions of oxygen and of forming two dif-ferent oxides; the black and the yellow.
TUNGSTIC ACID . The substance called tungstic acid byScheele and Bergman was discovered by Scheele in 1781. ThisPhilosopher obtained it from the tungstate of lime, by treating itwith nitric acid and ammonia alternately. The acid dissolves theln 'e, and the ammonia combines with the tungstic acid, t heaniinoniacal solution when saturated with nitric or muriatic acid,L e ,Posits a white powder, which is the tungstic acid of Scheele .
, , ls powder has an acid taste, it reddens vegetable blues, and is, lu hle in twenty parts of boiling water. The D Elhuyarts haveUe monstrated, that this pretended acid is a compound of yellowof tungsten, the alkali employed to dissolve it, and the,r ld used to precipitate it. Thus, when prepared according tome above described process, it is a compound of yellow oxide,Iat? 01lia * and nitric ucid. Their conclusions have been moreTv ^ co,1 finned by the experiments of VaiKjuelin and Hecht.
lls substance must therefore be erased from the class of acids,
and placed among the salts. The real acid of tungsten is a yel-low powder. This yellow powder, however, is found to be no otherbut the substance which has received the denomination of yellowoxide of tungsten. It ought rather, as Vauquelin and Hechthave properly remarked, to be classed among the oxides than theacids; for it is insoluble in water, tasteless, and has no effect onvegetable blues. It agrees with the acids indeed in the propertyof combining with alkalies and earths, and perhaps also with somemetallic oxides, and forming with them salts which have been de-nominated tungstates; but several other metallic oxides, those oflead, silver, and gold, for instance, possess the same property.These oxides, therefore, may be called acids with as much pro-priety as the yellow oxide of tungsten.
TUNG-TCHOUEN, a city of China , of the, first rank,capital of the province of Se-tchuen. Lon. 102. 25. E. Lat.27. 30. N.
TUNICA, a kind of waistcoat or under-garment, in use amongthe Romans. They wore it within doors by itself, and abroadunder the gown. The common people could not afford the toga,and so went in their tunics ; whence Horace calls them populustunicatus.
Tunica, in anatomy, is applied to the membranes which in-vest the vessels, and divers others of the less solid parts of thebody ; thus the intestines are formed of five tunics or coats. SeeAnatomy.
TUNIS, a country of Africa , in Barbary, bounded on the N.and E. by the Mediterranean and the kingdom of Tripoli, on theS. by several tribes of the Arabs, and on the W. by Algiers and thecountry of Esab; being 300 miles long from E. to°W. and 256in breadth from N. to S. This country was formerly a monar-chy ; but a difference arising between a k : ng and his son, one ofwhom was for the protection of the Christians, and the other forthat of the Turks, in 157-1, the inhabitants shook off the yoke ofboth. Erom this time it became a republic under the protectionof the Turks, and pays a certain tribute to the bashaw who residesat Tunis . The air in general is healthy ; but the soil in theeastern parts is indifferent for want of water. Towards the middlethe mountains and valleys abound in fruits; but the western partis the most fertile, because it is watered with rivers. The envi-rons of Tunis are very dry, upon which account corn is generallydear. The inroads of the Arabs oblige the inhabitants to sowtheir barley and rye in the suburbs, and to inclose their gardenswith walls. However, there are plenty of citrons, lemons,oranges, dates, grapes and other fruits. There are also olive-trees” roses, and odoriferous plants. In the woods and mountain*there are lions, wild beeves, ostriches, monkeys, camcleons, roe-bucks, hares, pheasants, partridges, and other sorts of birds andbeasts. The most remarkable rivers are the Guadilcarbar, Ma-grida, Magerada, and Caps. The principal religion, is Moham-medanism; but the inhabitants consist of Moors, Turks, Arabs ,Jews , and Christian slaves.
Tunis, a large and celebrated city, the capital of a kingdom ofthe same name. Lon. 10. 16. E. Lat. 36. 42. N.
TUNNAGEis used for a custom or impost, payable to thecrown, for go^ds and merchandize imported or exported, and isto be paid after a certain rate for every tun thereof. This duly,as well as that of poundage, was first granted for life to KingCharles II. and has been continued in the same mannerto his royal successors, down to his present majesty KingGeorge IV .
TUNNEL-NET, a net for taking partridges, which shouldnot exceed fifteen feet in length, nor be less tbari eighteen inchesin breadth, or opening, for the entrance.
TUNNY , in ichthyology. See Scomber.
TUP, in zoology. See Aries, and Ovis .
TUPIPORA, in natural history, a genus of the vermes zoo.phyta. Animal a nereis; coral consisting of erect, hollow, cylin-drical, parallel, aggregate tubes. There are ten species, of whichwe notice T. musica, with fasciculate connected tubes, andtransverse, distinct, membranaceous dissepiments. It inhabitsthe Indian and American Seas, fixed to rocks and other
corals.