Alkali

(al'ka-lī.) [Ar.] (Chem.) A name applied to a well-defined cla of bodies, which turn red litmus-paper blue, completely neutralize acids, are soluble in water, and, in solutions, exert a caustic action upon animal matter. The A. proper are the oxides of pota ium, sodium, lithium, rubinium, and crsium. To these must be added the compound alkali ammonia, the oxide of the' hypothetical metal ammonium, which used to be called the volatile alkali, in contradistinction to potash and soda, which were called fixed alkalies. (al-ka-lime-tre.) [Alkali, andGr. metron, measure.) (Chem.) The method of estimating the amount of alkali in alkaline liquids. It is ordinarily effected by the volumetric proce of analysis, by ascertaining how many divisions of a graduated tube containing an acid of definite strength are required to neutralize the liquid under examination. Alkaloid, (al'ka-loid.) [Alkali, and Gr. eidos, a re sem- | blance.] (Chem.) One of a very numerous and important cla of organic substances, which po e many of the properties of the alkalies of the mineral kingdom. Some A. are obtained exclusively from the vegetable kingdom, when they frequently constitute the active principle of the plant, as morphia, quinine, and strychnine. [s. 20]