Rubidium

(ru-bid' -e-um). Rb 85.3; quantivalence I. One of the rare alkaline metals, resembling pota ium in physical and chemic properties. See Elements, Table of R.-alum, an alum much resembling potash-alum, but le soluble in water. In Europe alum prepared from the mineral, bepidolite, sometimes contains a considerable proportion of rubidium-alum. Unof. R. -ammonium Bromid, a double salt of rubidium, introduced as a substitute for pota ium bromid. It is a white, crystalline powder, having a cooling, saline taste, and is readily soluble in water. It is used as a hypnotic and sedative, with special recommendation in the treatment of epilepsy. Dose 1 to 2 drams, in divided doses, best given in mixture with syrups flavored with lemon or orange. It has not been adopted generally, although endorsed by good authorities, and it is comparatively little known. R. Bromid, a serviceable but expensive substitute for pota ium bromid. Unof. R. Chlorid, unof., lowers the pulse-rate and raises the arterial tension. Dose red. gr. ij-v.