LITHIUM, a name applied to an alkali discovered in the year 1817. Lithia has since been detected in spodumene, lepidolite, triphy lite, amblygonite, tourmaline, meteoric stones, mineral waters, coffee, tea, blood, milk, etc. A process for procuring it is the following: One part of petalite or spodumene in fine powder is mixed intimately with two parts of fluor-spar, and the mixture is heated with three or four times its weight of sulphuric acid, as long as any acid vapors are disengaged. The silica of the mineral is attacked by hydrofluoric acid, and dissipated in the form of fluosilicic acid gas, while the alumina and lithia unite with sulphuric acid. After dissolving these salts in water, the solution is boiled with pure ammonia to precipi tate the alumnia; is filtered, evaporated to dry ness and then heated to redness to expel the sulphate of ammonium. The residue is pure sulphate of lithium. Its color is white; it is not deliquescent, but absorbs carbonic acid from the air; it is soluble in water; it is acrid and caus tic, and acts on colors like the other alkalis; heated with platinum it corrodes it rapidly. It combines with the different acids, and forms crystallizable salts with them. The phosphate and carbonate are sparingly soluble; the chloride is deliquescent and soluble in alcohol, and this solution burns with a red flame. Un like the other alkalis it cannot be reduced from its carbonate by carbon, but it requires the ac tion of a galvanic battery. The compound em
ployed is the chloride, which, while in a state of fusion, is acted on by the battery. Small globules collect round the negative pole, and these are removed and cooled under petroleum. It is the lightest of metals. It has a bright silver-white metallic lustre, melts at 356° F., and can be welded at ordinary temperatures. It is rather harder than potassium, can be drawn into a wire, but has a low degree of tenacity. Exposed to the air it tarnishes, but it combines with oxygen less rapidly than either sodium or potassium. It decomposes water, and when heated in oxygen, chloride and other gases burns with a brilliant light: Compounds of lithium are used in pyro techny on account of the splendid red color they impart to flame. In medicine the car bonate is employed especially as a solvent for uric acid, to prevent the formation of calculi and to remove it from the system in gout. Effervescing lithia water is sometimes used in place of soda or potash water. Citrate of lithia is also employed. It is a white, soluble, crystalline salt, prepared by dissolving the car bonate of lithium in citric acid. Its thera peutic properties are similar to those of the carbonate. See MINERAL PRODUCTION OF THE