Tellurium

Tellurium - Te = 125 - is a non-metallic element which occurs naturally both combined and in the free state, but only in very small quantities. The chief localities where the element is found are California, Hungary, and Brazil, and its chief compounds are its combinations with the metals silver, gold, and bismuth. When obtained pure, it is a white metal-like substance, which may be obtained in crystals of the Hexagonal system. It melts at about 500°, and distils at a higher temperature. It possesses a specific gravity of about 6.25. If heated strongly in air, it burns with a blue flame, and forms an oxide, TeO₂, which comes off as thick white fumes. The element is insoluble in acids, except strong sulphuric add, in which it dissolves to a deep-red solution. Chemically it resembles in many particulars the non-metals sulphur and selenium (q.v.,). Thus it forms a hydride, TeH₂, possessing a very disagreeable odour closely resembling that of sulphuretted hydrogen. It forms two oxides - a dioxide, TeO₂, and a trioxide, TeO₃ - both of which combine with bases to form salts, the tellurites and tellurates. The lower oxide also possesses basic properties itself, forming unstable salts with strong acids. The tellurates are for the most part insoluble, many of them being remarkable as existing in two modifications which differ in colour, solubility, and other physical properties.