STRONTIUM (Neo-Lat., from Strontion, Argyllshire, Scotland). A metallic clement first isolated by Davy in 1808, its earth having been recognized as a distinct chemical substance after ('rnikshank (1790), Hope (1792), and Klaproth (1793) had discovered that it gives a peculiar coloration if introduced into a flame. Strontium occurs as the carbonate (strontianite), as the sulphate (celed-dite), as the silicate in combina tion with barium aml calcium (brewsterite), also in small quantities in other minerals, such as arragonite, calcite, and dolomite. It further occurs in mineral and sea waters, and also in the ashes of certain plants. The metal may be obtained by the electrolysis of the moistened hydroxide or the chloride. Strontium (symbol, Sr; atomic weight, 87.01) is a yellow metal with a specific gravity of 2.5; it melts at a moderate red heat. It is both malleable and ductile, is less electropositive than calcium and the alkali metals, oxidizes quickly on exposure to the air, and burns brilliantly when heated. forming the
oxide. It combines with oxygen to form a mon oxide (Sr0) and a dioxide (Sr0,). The former is a gray-white, porous, infusible solid that is usually prepared loy igniting the nitrate. The hydrate formed by the action of water on the oxide has the property of combining with crystal lizable sugar to form a sacc•harate easily decom posed by carbon dioxide, and hence is extensively used for the separation of sugar from beet-root molasses. The nitrate, which may be prepared by dissolving the carbonate in warm dilute nitric acid and evaporating to crystallization, finds use for pyrotechnic purposes, owing to the red flame with which it burns.