LANTHANUM. L

a. Atomic Weight 139. One of the rare earth metals, first discovered in 1839 by Mosander in the cerite earths. It may be prepared by — electrolysis of the fused chloride, and occurs as an iron-grey metal which takes a high polish but tarnishes rapidly in the air, and becomes covered with white hydroxide in the presence of moisture. It has a specific gravity of 6.154 and ~ melts at 810° C. When heated in the air it forms oxide and nitride, and in hydrogen it yields lanthanum hydride. I? finely powdered and thrown into a flame, it burns brightly, and also burns in chlorine gas and bromine vapor, With aluminum it forms a white, crystalline alloy, consisting of approximately four parts aluminum to five parts lanthanum. ancient town, near Rome, Italy; had famous temple. Modern Civita Lavinia, volcanic island, Canary Islands, Atlantic; chief town, Arrecife. Pop. c. 18,000.