rubid1um

[Lat. rubidus =dark red.] Chem.: A monad metallic element belonging to the pota ium group, discovered by Kirchhoff and Bunsen in 1860. Symbol Rb; atomic weight, 854; specific gravity, 152. It has been detected in min eral waters, in several lepidolites, and in the ash of many plants, as tobacco, tea, and coffee. It may be obtained from the saline residue in the preparation of lithia from lepidolites, by adding platinic chloride, and di olving out the pota ium compound by repeated boiling with water. The chloro-platinate of rubidium is reduced with hydrogen, and the purified chloride of rubidium, mixed with calcium tartrate and soot, is heated in a furnace, the volatilized metal being collected in a receiver containing mineral naphtha. It is a white metal with silvery luster, soft to the touch, and melting at 38.5°. Exposed to the air, it becomes covered with a gray film, and soon takes fire. When thrown on water it takes fire even more readily than pota ium, and burns with a flame like the latter. rubidium-chloride, s . Chem.: RbCl. Obtained by adding hydrochloric acid to the hydrate and slowly evaporating. It forms cubic crystals which have a vitreous luster, are permanent in the air, and anhydrous. rubidium-hydrate, s. Chem.: RbHO. Formed by decomposing the sulphate of rubidium with barium hydrate, and evap orating the filtrate in a silver retort. It is obtained as a white porous ma , which deliquesces rapidly in the air, po e es caustic properties as powerful as hydrate of pota ium, and is soluble in alcohol. rû'-bied, pa.par.ora. [RUBY, v.] rû-bif-ic, *ru-bif-Ick, a . [Lat. ruber =red, and facio to make.] Making red; rubefacient.