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Page:Collier's New Encyclopedia v. 10.djvu/48

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obtained in the form of a brown powder by heating tungstic acid to low redness in a current of hydrogen, and which does not form salts with acids; and an acid oxide, known as tungstic anhydride, WO3. Various tungstates have been formed and examined. Of these the most important is the tungstate of soda, which answers admirably as a means of preventing muslin, etc., from bursting out in a flame when brought in contact with fire.

TUNGSTITE, a mineral occurring mostly as an earthy incrustation, but has been found in distinct cubic crystals at St. Leonard, near Limoges, France. Color, bright yellow or yellow-green. Composition: Oxygen, 20.7; tungsten, 79.3=100, with the formula WO3. Called also tungstic acid and tungstic ocher.

TUNIC, in classical antiquities, a very ancient form of garment in constant use among the Greeks and ultimately adopted by the Romans. The Roman tunic was a sort of shirt worn under the toga, and buckled round the waist by a girdle. It reached an inch or two below the knees, and the sleeves were so short that they merely covered the shoulders; for though tunics hanging down to the ankles (tunicæ talares), and with sleeves extending to the wrists and terminating in fringes (tunicatæ manicatæ et fimbriatæ) were not unknown toward the close of the republic, they were always regarded as indications of effeminate foppery.

TUNING, the correct adjustment of the sounds of a musical instrument. Such instruments as the flute and horn are tuned without any difficulty, as, if the pitch is altered by accident, it affects every note, and may easily be rectified by varying the length of the pipe. The notes of the organ and pianoforte, however, are unconnected and independent, and require careful adjustment from time to time. Stringed instruments, such as the violin and harp, require tuning on every occasion on which they are used.

TUNING FORK, an instrument of steel, consisting of two prongs, branching from a short handle, which, when set in vibration, gives a musical note. It was invented by John Shore, in 1711. Though the pitch of forks varies slightly with changes of temperature, or by rust, etc., they are the most accurate means of determining pitch. They are capable of being made of any pitch within certain limits, but those most commonly used are the notes A and C, giving the sounds represented by the second and third spaces in the treble stave. The vibration number of the note C varies from 518 (French diapason-normal) and 528 (Scheibler-medium) to 540 and 544 (Philharmonic).

TUNIS, a country of north Africa, now a French protectorate; bounded on the N. and N. E. by the Mediterranean, on the S. E. by Tripoli, and on the W. and S. W. by Algeria; area, estimated at 51,000 square miles; pop. about 1,900,000. The coast line presents three indentations, forming the Bay of Tunis on the N., and those of Hammamet and Cabes or the Lesser Syrtis on the E. The N. W. portion of the country is traversed by the Atlas Mountains, which on their lower slopes have many fertile tracts, partly under culture. Between these mountains and the Gulf of Hammamet on the E. stretches the extensive plain or plateau of Kairwan. The only river of any consequence is the Mejerdah. In 1900 there were 883 miles of railway, of which 866 belong to the state. Agriculture is very much neglected; the principal crops are wheat, barley, and maize; olive plantations are numerous, while tobacco is largely, and cotton, indigo, saffron, and opium partially, grown. On several parts of the coast the fisheries, including that of coral, are valuable. The manufactures consist chiefly of woolen fabrics, soap, dyed skins, and ordinary and morocco leather. The inhabitants consist of a mixture of Moors and Arabs, along with Berbers, here called Kroumirs, occupying the elevated tract N. of the valley of Mejerdah. In ancient times Tunis belonged to the Carthaginians, afterward formed part of the Roman province of Africa, was subdued about 675 by the Arabs, became a powerful state under independent rulers in the 13th century, and in 1575 was incorporated with the Ottoman empire. In the spring of 1881 the French invaded Tunis, in order to punish the turbulence of the Kroumirs, and the French minister resident is now the virtual ruler of the country. Under French administration the Tunisian debt has been consolidated, commerce has increased, the means of transit have been improved, and a number of primary schools established. The exports in 1918 amounted to £5,181,728, and imports to £8,297,718.

TUNIS, a city and capital of the protectorate of the same name; situated at the head of a salt lake, nowhere more than 6 feet deep, which communicates by a narrow channel with the Gulf of Tunis, an inlet 30 miles long. At the outlet of the lake is Goletta, the port of Tunis, whose harbor is a roadstead with good anchorage, and is sheltered from the N. Goletta is connected by railway with Tunis, which is a walled, fortified, and straggling city, whose winding streets