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STRONTIUM [Symbol Sr, atomic weight 8...

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Originally appearing in Volume V25, Page 1041 of the 1911 Encyclopedia Britannica.
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STRONTIUM [See also:Symbol Sr, atomic See also:weight 87.62 (0=16)] , a metallic chemical See also:element belonging to the alkaline See also:earth See also:group. It is found in small quantities very widely distributed in various rocks and soils, and in See also:mineral See also:waters; its See also:chief See also:sources are the minerals See also:strontianite, See also:celestine and barytocelestine. The See also:metal was detected in the mineral strontianite, found at Strontian in See also:Argyllshire, by See also:Cruikshank in 1787, and by See also:Crawford in 1790; and the See also:discovery was confirmed by See also:Hope in 1792 and by See also:Klaproth in 1793. The metal was isolated in 1807 by See also:Sir H. See also:Davy by electrolysing the moist hydroxide or chloride, and has been obtained by A. Guntz and See also:Roederer (Comptes rendus, 1906, 142, p. 400) by See also:heating the hydride in a vacuum to See also:I000°. By electrolysing an aqueous See also:solution of the chloride with a See also:mercury See also:cathode, a liquid and a solid See also:amalgam, SrHg11, are obtained; the latter on heating gives a mixture of Sr2Hgs and SrH$6, and on See also:distillation an amalgam passes over, and not the metal. It is a See also:silver-See also:white ductile metal (of specific gravity 2.54) which melts at 800°. It oxidizes rapidly when exposed to See also:air, and See also:burns when heated in air, See also:oxygen, See also:chlorine, See also:bromine or See also:sulphur vapour. With dry See also:ammonia at 6o° the metal forms strontium ammonium, which slowly decomposes in a vacuum at 2o° giving Sr(NH3)2 ; with See also:carbon monoxide it gives Sr(CO)2; with oxygen it forms the monoxide and peroxide, and with nitric See also:oxide it gives the hyponitrite (Roederer, See also:Bull. See also:sac. chim., 1906 [iii.], 35, P. 715)• The hydride, SrH2, was obtained by Guntz on heating strontium amalgam in a current of See also:hydrogen.

It is a white solid, which readily decomposes See also:

water in the See also:cold and behaves as a strong reducing See also:agent. It dissociates when heated to a high temperature and is not affected by oxygen. The monoxide or strontia, Sr(); is formed by strongly heating the nitrate, or commercially by heating the sulphide or carbonate in superheated See also:steam (at about 500-60o° C.). It is a white amorphous See also:powder which resembles See also:lime in its See also:general See also:character. By heating the amorphous See also:form in the electric See also:furnace H. See also:Moissan succeeded in obtaining a crystalline variety. The amorphous form readily slakes with water, and the aqueous solution yields a crystalline hydrated hydroxide approximating in See also:composition to Sr(OH)2.8H20 or Sr(OH)2.9H20, which on See also:standing in vacuo loses some of its water of See also:crystallization, leaving the monohydrated hydroxide, Sr(OH)2-H20. The See also:ordinary hydrated variety forms quadratic crystals and behaves as a strong See also:base. It is used in the extraction of See also:sugar from See also:molasses, since it combines with the sugar to form a soluble saccharate, which is removed and then decomposed by carbon dioxide. A hydrated dioxide, approximating in composition to SrO2'8H20, is formed as a crystalline precipitate when hydrogen peroxide is added to an aqueous solution of strontium hydroxide. Strontium fluoride, SrF2, is obtained by the See also:action of hydrofluoric See also:acid on the carbonate, or by the addition of See also:potassium fluoride to strontium chloride solution. It may be obtained crystalline by fusing the anhydrous chloride with a large excess of potassium hydrogen fluoride or by heating the amorphous variety to redness with an excess of an alkaline chloride.

Strontium chloride, SrCl2.6H20, is obtained by dissolving the carbonate in hydrochloric acid, or by fusing the carbonate with See also:

calcium chloride and extracting the melt with water. It crystallizes in small See also:colour-less needles and is easily soluble in water; the concentrated aqueous solution dissolves bromine and See also:iodine readily. By concentrating the aqueous solution between 90-130° C., or by passing hydrochloric acid See also:gas into a saturated aqueous solution, a second hydrated form of composition, SrC12.2H20, is obtained. The anhydrous chloride is formed by heating strontium or its monoxide in chlorine, or by heating the hydrated chloride in a current of hydrochloric acid gas. It is a white solid, which combines with gaseous ammonia to form SrCl2 8NH3, and when heated in superheated steam it decomposes with See also:evolution of hydrochloric acid. Strontium sulphide, SrS, is formed when the carbonate is heated to redness in a stream of sulphuretted hydrogen. It phosphoresces very slightly when pure. Strontium sulphate, SrSO4, found in the mineral See also:kingdom as celestine, is formed when sulphuric acid or a soluble sulphate is added to a solution of a strontium See also:salt. It is a colourless, amorphous solid, which is almost insoluble in water, its solubility diminishing with increasing temperature; it' is appreciably soluble in concentrated sulphuric acid. When boiled with alkaline See also:carbonates it is converted into strontium carbonate. Strontium nitride, Sr3N2, is formed when strontium amalgam is heated to redness in a stream of See also:nitrogen or by igniting the oxide with See also:magnesium (H. R.

See also:

Ellis, Chem. See also:News, 1909, 99, p. 4). It is readily decomposed by water, with liberation of ammonia. Strontium nitrate, Sr(NOa)2, is obtained by dissolving the carbonate in dilute nitric acid. It crystallizes from water (in which it is very soluble) in See also:monoclinic prisms which approximate in composition to Sr(N0a)2-4H20 or Sr(NOa)2-5H20. When heated it fuses in its own water of crystallization and becomes anhydrous at See also:Ito° C. It is used in pyrotechny for the manufacture of red-See also:fire. A strontium boride, SrB6, was obtained as a See also:black crystalline powder by H. Moissan and P. See also:Williams (Comptes rendus, 1897, 123, p. 633) by reducing the borate with See also:aluminium in the electric furnace.

Strontium See also:

carbide, SrC2, is obtained by heating strontium carbonate with carbon in the electric furnace. It resembles calcium carbide, decomposing rapidly with water, giving See also:acetylene. Strontium carbonate, SrCO3, found in the mineral kingdom as sttontianite, is formed when a solution of a carbonate is added to one of a strontium salt. It is an amorphous solid, insoluble in water, but its solubility is increased in the presence of ammonium nitrate. It loses carbon dioxide when heated to high temperature. Strontium salts may be recognized by the characteristic See also:crimson colour they impart to the See also:flame of the See also:Bunsen burner and by the precipitation of the insoluble sulphate. On the preparation ofpure strontium salts, see See also:Adrian and Bougarel, Journ. pharm. chem., 1892 (5), p. 345; and S. P. L. Soerenoen, Zeit. anorg. chem., 1895, II, p. 305.

See also:

Recent determinations of the atomic weight of strontium are due to "T. W. See also:Richards (Zeit. anorg. Chem., 1905, 47, p. 145), who, by estimating the ratios of strontium bromide and chloride to silver, obtained the values 87.663 and 87.661.

End of Article: STRONTIUM [Symbol Sr, atomic weight 87.62 (0=16)]

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