Page:The American Cyclopædia (1879) Volume XV.djvu/712

 082 THALER In 1845 ho married a daughter of Lablache. Ilia last public appearance was at Paris in 1865. After that he retired to his estate near Naples, where he devoted himself to the cultivation of the vine. His daughter ZAIRE, born in New York in 1858, made a successful debut as Zer- lina in Don Giovanni, at Covent Garden, Lon- don, April 10, 1875. THALER (Dan. and Swed. daler), a coin and money of account of Germany, Austria, Hol- land, Belgium, Denmark, Sweden, and Nor- way. Silver coins of an ounce weight were struck in the early part of the 16th century at Joachimsthal, a town in Bohemia, whence the name. (See DOLLAR.) Other countries after a time began to coin thalers, but not always of the same value, and hence originated the Laubthaler or leaf dollar, the Phttippstlialer, the Swedish copper dollar, &c. In most of the countries of Europe the royal or imperial mints coined thalers, hence called rigsdaler, riksdaler, or Reich&thaler, that is, dollar of the realm. These varied in value according to the amount of alloy. (See COINS.) As money of account there is still greater diversity of values, owing to the depreciation of the issues of the national banks or treasuries. In Sweden the rigsdaler riksmynt, now the authorized money of account, is about 27 cts. In Denmark the rigsbank daler is about 54 cts. In Germany generally the thaler of account is reckoned at 69 to 73 cts. American currency. THALES, a Greek philosopher, and one of the seven wise men, born in Miletus, Ionia, about 636 B. 0., died probably about 546. He took an active part in the political affairs of his native country. He visited Crete and Egypt, and acquired in the latter country an acquaintance with geometry. Various physi- cal discoveries are attributed to him. He mea- sured the height of the Egyptian pyramids by observation of the time at which a shadow equalled in length the height of the object ; and he is said to have computed the sun's orbit, to have fixed the length of the year at 365 days, and to have been the first among the Greeks to predict eclipses, though very vague- ly. Aristotle calls him the originator of the Ionic natural philosophy, and hence, indirectly, of Greek philosophy in general. He taught that all things are instinct with life, and ori- ginate from water. The writings attributed to him were declared spurious in antiquity, and his sayings recorded by Aristotle and Diogenes Laertius are probably conjectural. THALIA, in Greek mythology, the muse of comedy and idyllic poetry. She is generally represented with a mask in one hand and a shepherd's staff or a wreath of ivy in the other. THALLIUM (Gr. 6aU6<;, a green bough), one of the three metals forming the class of triads, the others being iridium and gold. It was dis- covered by Crookes of London in 1861, in the seleniferous residue from the manufacture of sulphuric acid from iron pyrites. Its discovery resulted from the observation by Mr. Crookes THAMES of a green band in the spectrum of the vapor- ized portion of the residue. It is widely dif- fused as a constituent of iron and copper py- rites, but forms only about the 4,000th part of the mass. It also exists in the lepidolite of Moravia, in mica from Zinnwald in Bohemia, in the mother liquors of the salt works at Nauheim, and in the mineral crookesite from Skrikerum in Norway. It is most economically prepared from the flue dust of pyrites burners. This dust is stirred with boiling water in wood- en tubs, and the decanted or syphoned liquor treated with an excess of strong hydrochloric acid, by which impure monochloride of thal- lium is precipitated. This impure chloride is then treated with hot oil of vitriol, and con- taminations of other metals are separated by sulphuretted hydrogen. A pure sulphate is ob- tained, from which the metal may be separated by electrolysis or the action of zinc. Thallium resembles cadmium in color, but approaches lead in specific gravity, having a density of 11*8 to 11'91, according to its metallurgic treat- ment. The symbol of thallium is Tl ; its atomic weight, according to recent extended researches by its discoverer, is 203-642. (See " Chemical News," London, 1874.) It has a highly crys- talline structure, and crackles like tin when bent, but is easily hammered into leaves. It melts at 561 F. A polished piece of the metal tarnishes rapidly when exposed to the air, but the action continues only a short time, as the thin film of oxide protects it from further oxi- dation. The metal and its compounds impart an intense green color to colorless flames, which when viewed by the spectroscope is found to be monochromatic, appearing as a sharply de- fined green band. It forms numerous com- pounds, including three oxides, the most im- portant being thallous oxide, T1 2 O ; this dis- solves readily in water, producing a caustic alkaline solution which absorbs carbonic acid from the air. The sulphate forms with alu- minic sulphate an octahedral alum. The salts of thallium are poisonous. The metal has been used to render glass highly refractive. THAMES, a river of Connecticut, formed by the junction of the Quinebaug (with its branch the Shetucket) and Yantic rivers at the city of Norwich, and flowing thence S. about 15 m. to Long Island sound, which it enters below New London. It is wide and beautiful, navigable for large vessels to Norwich, and has an excel- lent harbor at its mouth. The streams which form it possess numerous valuable mill sites, and the large amount of manufactured goods from the factories on their banks make the Thames an important avenue of commerce. THAMES, a river of Ontario, Canada, flowing through a fertile country in the peninsula formed by Lakes Huron and Erie, and after a S. W. course of about 160 m. discharging into Lake St. Clair. It is navigable for small ves- sels from its mouth to Chatham, 18 m. The city of London is the most important place on its banks. At the Moravian settlement on this