Lithium, a metal first obtained by Davy; symbol Li, chemical equivalent 7. (See Lithia.) It is most easily reduced from the chloride by the galvanic current. It is a soft, ductile, white metal, susceptible of being welded and drawn into wire, but has less tenacity than lead. It fuses at 356°, and is not volatilized at a red heat. It is the lightest metal known, its specific gravity being only 0.5936. It burns brilliantly, floats upon water and naphtha, and soon abstracts oxygen, its behavior being like that of sodium. It was supposed to be a very rare substance, but Bunsen and Kirchhoff have shown by spectrum analysis that, though sparingly, it is widely distributed. - Three salts of lithium, the carbonate, citrate, and bromide, are used in medicine. Of these the first two are more powerfully diuretic than the corresponding salts of sodium or potassium, and from their low combining numbers a smaller dose suffices to render the urine alkaline. The compound formed by lithia with uric acid is very soluble, and these salts have accordingly been recommended and used in the treatment of gout (in which disease an excess of uric acid is found in the blood), being administered either in the form of an ordinary pharmaceutical solution or mixture, or as natural or artificial mineral waters.
The action of the bromide of lithium is similar to that of the bromide of potassium, but is said to be effective in cases in which the latter fails.