Page:EB1911 - Volume 26.djvu/390

Rh cut. The word talc, sometimes written talk, is said to come from the Arabic talq, and not to be connected, as has been fancifully suggested, with the Swedish tälja, “ to cut.” Talc and mica were confused by the older writers, and even at the present day mica is sometimes known in trade as talc; whilst the term was formerly applied also to foliated gypsum.

Talc is found occasionally in small hexagonal and rhombic plates, with perfect basal cleavage, and they are supposed to be mono clinic. Talc often occurs in foliated masses, sometimes with a curved surface, readily separating into thin very flexible, non-elastic laminae. The plates give a six-rayed percussion-figure. Talc has a hardness of only about 1, and a specific gravity of from 2.6 to 2.8. Its extreme softness and its greasy feel are characteristic. The lustre on the cleavage face is pearly, or sometimes silvery, and one of the old names of the mineral was stella terrae, while German writers sometimes called it Katzensilber. The colour is white, grey, yellow or frequently green. The mineral has strong birefringence and a small optic axial angle.

Talc is a magnesium silicate H2Mg3Si4O12. It is generally regarded as a hydrous silicate, but the water is expelled only at a very strong heat, and may therefore be regarded as basic. By the action of heat the hardness of the mineral is greatly increased. Pseudomorphs are known after actinolite, pyroxene, &c., and the mineral has probably been generally formed by the alteration of ferro-magnesian silicates. Talc occurs chiefly in crystalline schists, usually associated with chlorite, serpentine and dolomite. Fine examples of apple-green colour are found at Mount Greiner, in the Zillerthal, Tirol. Talc-schist is a foliated rock composed chiefly of tale, generally associated with quartz and felspar; but all soapy schists are not necessarily talcose. The pearly micaceous constituent of the Alpine protogine is a muscovite.

The “ steatites ” of Pliny was a stone resembling fat, but otherwise undescribed. Being easily cut, steatite has always been a favourite material with the carver: it was used for Egyptian scarabs and other amulets, which were usually coated with a blue vitreous glaze; and it was employed for Assyrian cylinder seals and for other ancient signets. By the Chinese steatite is largely used for ornamental carvings, but many of their “ soapstone” figures are wrought in a compact (q.v.), which is essentially different from talc. The name agalmatolite is often applied to the material of these figures, and was suggested by M. H. Klaproth from the Greek ἄγαλμα, “ an image.” Pagodite is an old name for Chinese figure-stone. Ancient steatite carvings are found among the ruins of Rhodesia.

Steatite is usually a white, grey, greenish or brown substance, occurring in veins or nodular masses or in lenticular bedded deposits. Pseudomorphs after quartz and dolomite occur near Wunsiedel in Bavaria. In some cases it is a product of the alteration of pyroxenic rocks, and the commercial mineral may be very impure. The ease with which steatite may be worked, coupled with its power of resisting heat, has led to its employment for vessels for household use, whence it is called “ potstone ”—the lapis ollaris of old writers. Among the uses of steatite may be mentioned its employment, especially in America, for sinks, stoves, firebricks, foot-warmers, tips for gas burners and electric switchboards: when ground it is used as a tiller for paper, for leather-dressing, for covering steam-pipes, as an ingredient in soap, for toilet-powder, for certain paints and as a lubricant. A fine granular steatite is used by tailors for marking cloth under the name of “ French chalk ” or “ Spanish chalk.” Slate pencils are made of steatite and pyrophyllite; and in Burma steatite pencils are used for writing on black paper. In the oxyhydrogen flame, steatite has been fused and drawn out into threads, like quartz-fibres.

Steatite and talc-schists are widely distributed, and have occasionally been used as building stones. When first raised the stone is soft, but hardens on exposure. Soapstone from Gudbrandsdal is used in the cathedral of Trondhjem in Norway. Veins of steatite occur in the serpentine of the Lizard district in Cornwall, and the mineral was used under the name of soap rock in the manufacture of the old Worcester porcelain. Among localities of steatite in the British Isles mention may be made of Crohy Head and Gartan near Letterkenny in co. Donegal, Ireland; the Shetland isles, the Hebrides (Harris) and Shiness in Sutherland. In North America the distribution of the mineral is very extensive; localities of economic importance are near Gouverneur and elsewhere in St Lawrence co., New York; at Francestown in New Hampshire; Stockbridge, Windsor co., Vermont; Lynnfleld, Massachusetts; near Lafayette, Pennsylvania; Albemarle, Amelia, Buckingham, Fairfax and Fluvanna cos., Virginia; Cherokee, Moore and Swain cos., North Carolina; and in Murray co., Georgia.

A fibrous steatite from New York state, used in the manufacture of paper, is known as agalite. Rensselaerite is a wax-like talcose substance, passing into serpentine, from St Lawrence co., New York, named by E. Emmons in 1837 after S. Van Rensselaer, of Albany, N.Y. Beaconite is an asbestiform talc from Michigan, named by L. W. Hubbard. The term pyrallolite was given by Nils G. Nordenskiöld to a mineral from Finland, which appears to be talc pseudomorphous after pyroxene. Talcoid was K. F. Naumann's name for a white lamellar mineral from near Pressnitz in Bohemia. A blue earthy mineral from near Silver City, New Mexico, known locally as “ native ultramarine," is a magnesium silicate.

See “ Talc and Soapstone ” in vol. ii. of Mineral Resources of the U.S. (Washington, 1909), and J. H. Pratt, “ Economic Papers," No. 3 of Geol. Surv. of N. Carolina (1900); also E. Parker in 19th Report of U.S. Geol. Surv. (1898); C. H. Smyth, junior, The Fibrous Talc Industry of Si Lawrence Co., N.Y., in “ Mineral Industry," vol. ix., for 1900; and G. P. Merrill's Non-metallic Minerals (New York, 1904).

TALCA, a province of Chile, bounded N. by Curico, E. by Argentina, S. by Linares and Maule, and W. by the Pacific. Area 3840 sq. m. Pop. (1895) 128,961. In the E. the Andean slopes cover a considerable part of its territory, and in the W. another large area is covered by the coast range. Between these is the central valley of Chile in which the population and industries of the province are chiefly concentrated. The mountainous parts are well wooded. The intermediate plain, which is rolling and slopes gently to the S., is fertile and devoted to wheat and stock. The capital of the province is Talca (pop. 1895, 33,232; 1902 estimated 42,766), on the Rio Claro, a tributary of the Maule, 156 m. by rail S. of Santiago. It is one of the most important provincial towns and commercial centres of central Chile. There are woollen factories, especially for the universally worn “poncho.” Talca has railway connexion with Santiago on the N., with Concepción on the S., and with Constitución at the mouth of the Maule.

TALCAHUANO, or, a seaport of the province of Concepción, Chile, on the bay of Concepción, 8 m. N.W. of the city and port of that name. Pop. (1895) 10,431; (1902, estimated) 13,499. It is sheltered by the island of Quiriquina. It has the best harbour on the Pacific coast of South America, and is one of the most important ports of southern Chile, being connected by rail with Concepción, Santiago and southern Chile. Its foreign trade is large and steadily increasing. The Chilean government has established its chief naval depot here.

TALE (O.Eng. talu, number, account, story; the word is common to many Teutonic languages; cf. Ger. Zahl, number, Erzählung, narrative, Du. taal, speech, language), a general term, in the usual acceptance of the word, for fictitious narratives, long or short, ancient or modern (see ). In this article “ tale ” is used in a stricter sense, as equivalent to the German “ Volks-märchen ” or the French “ conte populaire.” Thus understood, popular tales mean the stories handed down by oral tradition from an unknown antiquity, among savage and civilized peoples. So understood, popular tales are a subject in mythology, and indeed in the general study of the development of man, of which the full interest and importance was long unrecognized. Popular tales won their way into literature, it is true, at a very distant period. The Homeric epics, especially the Odyssey, contain adventures (those, for example, of the Cyclops and the husband who returns in disguise) which are manifestly parts of the general human stock of popular narrative. Other examples are found in the Rigveda, and in the myths which were handled by the Greek dramatists. Collections of popular tales, more or less subjected to conscious literary treatment, are found in Sanskrit, as in the work of Somadeva, whose Kathā Sarit Sāgara, or “ Ocean of the Streams of Story,” has been translated by Mr Tawney (Calcutta, 1880). The (q.v.)