TELLURIUM (symb. Te, equiv. 64—new system, 128—spec. gray. 6.183) is a chemi cal element, which some authorities place among the metals, and others among the non metallic bodies or metalloids. Although in its outward characters it closely resembles the metals, its close analogies with sulphur and selenium indicate that its true place is among the metalloids. It possesses a high metallic luster, and resembles bismuth in color; it fuses at about 850°, and at a higher temperature is converted into a yellow vapor; it is a bad conductor of heat and electricity. When strongly heated in the air it burns with a blue flame, and gives off white furqes of tellurous acid. Like sulphur and selenium, it is soluble in cold oil of vitriol, to which it gives a fine purple-red color, and on dilution it is precipitated unchanged; and in these respects differs from all metals. In nitric acid it dissolves with oxidation.
Tellurium forms two compounds with oxygen, viz., tellurous acid, and telluric acid, Tellurous acid exhibits very slight acid properties, and in the anhydrous state it combines with acids, and acts the part of a weak base. These salts have a metal lic taste, and are said to act powerfully as emetics. The telluric acid has only a feeble affinity for bases, but it forms salts, which contain 1, 2, and 4 atoms of the acid to each atom of base. Tellurium unites with hydrogen to form tellureted hydrogen, Tell,
which is a gaseous body, analogous to sulphereted hydrogen, and precipitates most of the metals from their solutions in the form of tellurides, which have a close analogy with the corresponding sulphides.
In experimenting upon the action of the salts of tellurium, it has been found that they possess the power of forming, in the of a healthy person, compounds which impart to the breath, to the perspiration, and to the gases generated in the intestinal canal, a disgusting fetor, which makes him a nuisance to every one he approaches; and this smell may last for weeks, although the quantity of tellurium that was administered did not exceed a quarter of a grain.
Tellurium is a rare substance, found chiefly in Transylvania, but recently discovered in Hungary, in North America, and in the Altai silver mines. It sometimes occurs na tive, but more commonly as a telluride of gold, lead, or silver. For the method of extracting it, we must refer to any of the larger works on chemistry, and especially to the Lehrbuch of Berzelius. It was discovered in 1782 by Midler von Reichenstein, but it was not till 1798 that its properties were accurately studied by Klaproth. The word tellurium is derived from the Latin talus, the earth.