Page:The American Cyclopædia (1879) Volume XV.djvu/583

 TALC TALC, a silicious mineral occurring in two forms, crystalline and massive. The massive variety was formerly called steatite (soapstone), and was regarded as a distinct species ; but it has the same chemical composition as crystal- line talc, viz., 4MgO,5SiO 2 f H 2 O, or silica 62-14, magnesia 32-92, and water 4-94 per cent., be- ing a hydrous silicate of magnesia. Talc is com- monly in the form of lamellar crystals, which cleave perfectly in one direction, but are usu- ally too incompletely developed to allow of an exact determination of their crystalline sys- tem ; but hexagonal prisms and plates are oc- casionally found. They are optically biaxial. The lamellsB are very flexible but not elastic, and are unctuous to the touch. Talc is very soft, being only 1 on the scale of 10; sp. gr. from 2-6 to 2'8; lustre pearly; color apple- green to white, also greenish gray to dark green, subtranslucent. Talc, either in a foliated or la- mellar form, or massive as steatite, is common, forming extensive beds in some localities. It is often associated with serpentine, talcose, or chloritic schist. Steatite or soapstone is known in different localities as potstone (Topf stein), lapis ollaris, rensselaerite, and French chalk (craie de Briangon}. There are extensive quar- ries at Grafton, Athens, Westfield, and Marl- borough, Vt. ; at Francestown, Pelham, and Keene, 1ST. H. ; at Middlefield, Chester, and other places in Massachusetts ; in Maryland near Baltimore, in Virginia near Washington and in London co., and in Guilford co., N. C., and numerous other places, in metamorphic rocks. It is used for making stoves, ovens, and hearths; for sizing-rollers in cotton fac- tories, on account of its not being affected by acids; and sometimes as a lubricant for journals. It is also used for slate pencils and crayons, and for the stoppers of chemical ves- sels. The American aborigines use it for cul- inary articles, and the Chinese for the carv- ing of idols. TALENT (Gr. rdAavrov; Lat. talentum), a term originally applied by the ancient Greeks to a balance for weighing, afterward to the substance weighed, and finally to the weight itself. In the system of weights in use the talent was the highest denomination, and was equivalent to 60 minas, each of which was equal to 100 drachmas, and each of these to 6 oboli. The values of these weights remained constant in relation to each other, while that of the units of the measure varied in different times and in different places. The system of money being based upon the weight of silver, the names of the weights employed came to be used as money values, in the same way as the English pound originally represented a pound weight of silver. No coins however are known to have been made larger than the tetradrach- ma, and the mina and talent were moneys of account only. The determination of the weights of the different talents in terms of our modern standards is a subject involved in great diffi- culty, and there is a marked disagreement TALFOURD 555 among scholars. The oldest talent was the Babylonian, which was carried into the Phoeni- cian and Grecian countries, and may with great probability be assumed as identical with the oldest Greek talent, called the jEginetan. The Hebrew talent differed but little if at all from this. The Euboic talent, also probably derived from the East, was in use in Attica previous to the time of Solon, and is often called the old Attic; it continued in use after the time of Solon, and hence was also called the com- mercial talent. Solon, in order to relieve the debtor class, reduced the talent so far as money was concerned, and the talent established by him, called the new Attic or Attic silver talent, is the one always meant in the classical authors when the context does not indicate a different one. The ratio of these talents to each other was as follows, in whole numbers : 15 JEgine- tan talents were equal to 18 Euboic or commer- cial talents, and to 25 Solonian or Attic silver talents. Their weights compared with our avoirdupois weight were probably as follows : the ^Eginetan equalled 95 Ibs. ; the Euboic, 79 Ibs. 2 oz. 291-63J gr. ; the Attic silver talent, 57 Ibs. The value of these talents in pure silver, taking the American trade dollar, con- taining 378 gr. of pure silver, as the standard, would be as follows : the JEginetan talent equals $1,759 26; the Euboic, $1,466 05; the Attic silver talent, $1,055 56. The coins in actual use fell below this standard both in weight and in purity, and varied in different ages. For approximate calculation the coin value of the above named talents may be as- sumed as equal to $1,700, $1,400, and $1,000 respectively. Various other talents are named by the ancient writers, the comparative values of which have been treated in the works of Bockh and of Hussey. The gold talent of the Greeks, or the Sicilian talent, the one always meant in Homer, contained about oz. and 71 gr. avoirdupois of gold. TALFOERD, Sir Thomas Noon, an English au- thor, born at Doxey, a suburb of Stafford, Jan. 26, 1795, died in Stafford, March 13, 1854. He was called to the bar in London in 1821, and in 1833 was made serjeant at law. From 1835 to 1841 he was member of parliament for Reading, and again from 1847 to 1849, when he was made a judge of the court of common pleas. In parliament he was distinguished by his efforts in behalf of the rights of authors, for whose benefit he introduced in 1837 the copyright act which, somewhat modified, was passed in 1842. His tragedy of " Ion " (1835) was acted with great success under the direc- tion of Mr. Macready, and was followed by "The Athenian Captive" (1838), "Glencoe" (1840), and " The Castilian " (1854). The last was not acted, and " The Athenian Captive " and " Glencoe " were but moderately success- ful on the stage. His other works include me- moirs and correspondence of his friend Charles Lamb (1837 and 1838, subsequently published as one work), and "Final Memoirs" (1848).