STRONTIUM (symb. Sr, equiv. 43.8—new system, 87.6—sp. gr. 2.54) is a ductile end malleable metal, somewhat harder than lead, And of a pale yellow color. When heated in the air, it burns with a crimson flame, and becomes converted into its oxide, strum in. It is unaffected by the action of dry air, but it decomposes water at an ordinary temrcra tore, hydrogen being explosively developed; and it burns in chlorine ges, and in the vapor of iodine, bromine. and sulphur. ' It dissolves in dilute nitric acid, but the strong acid has scarcely any effect on it. This metal does not occur in the native state, hut exists as a carbonate in the mineral strontianite (so called from its being first found rear Strontian, in A rgyleshirc), and as a sulphate in the mineral known as celestine (so called room its delicate blue tint). It is obtained by the voltaic decomposition of the chloride of strontium. This natal bears to barium the same close relation that sodium N. ass to potassium; and the compounds of strontium resemble those cf barium not only in their composition hut in their properties.
The oxide of strontium, commonly known as STRONTIA, is obtained in the same way, and resembles in almost all respects the corresponding oxide of barium, except that it is inert when taken into the system, while haute, is poisonous. When a small quantity of water is poured upon it, it slakes, giving out heat.
The salts of strontia resemble those of baryta in their general characters, and in their being precipitated from their solutions by sulphuric acid and the soluble sulphates; but they differ from them in not being thrown down by silico-flooric acid or hyposolphite of soda, and in their communicating to the flame of the spirit-lamp and to burning sub stances generally, a brilliant purple-red color. The salts of strontia occur only in the mineral kingdom, and are never found as normal ingredients of organic bodies. Ca Km ate of strontia occurs native both in a massive and crystalline form, and may be obtained artificially as a white powder by precipitating a soluble salt of strontium with carbonate of soda. Sulphate of strontia occurs native in celestine, a mineral which is
found in beautiful rhombic prisms in Sicily. _Nitrate of strontia (SrO,N0,) surarates from a hot concentrated solution in large colorless transparent anhydrous ell:111(41ra] crystals, which dissolve freely in water. By the addition of nitric acid, it is precipitated from its aqueous solution. This salt is insoluble in alcohol; but when finely powdered, and mixed with it, it communicates to the alcoholic flame a beautiful red or crimson color. In consequence of this property, it is employed by the makers of fireworks. A mixture of 40 parts of nitrate of strontia with 10 of chlorate of potash, 13 of sulphur, and 4 of sulphide of antimony, deflagrates with a magnificent red color, and constitutes who is popularly known as red Bengal fire; but the mixture is dangerous both to prepare and to preserve, having more than once been the occasion of frightful accidents to the manufacturers from its becoming ignited spontaneously.
The most important of the lialoid salts of strontium is the chloride (SrCI), which may be obtained in crystals containing six equivalents of water. The water is expelled at a moderate heat, leaving the chloride anhydrous. The chloride is the only salt from which the metal has hitherto been obtained.
• Regarding the history of this metal, it may be observed that strontia was discovered as an independent substance almost simultaneously by Hope and Klaproth in 1793. In 1807 Davy obtained barium and strontium from their oxides, but not in a pure state; and it was not till 1853 that Bunsen and Matthiessen succeeded in procuring perfectly pure specimens of the metal.