Allotropy

(al-loťro-pe.) [Gr. allos, another, and trophos, habit.] (Chem.) That branch of the science which takes account of the different sets of properties po ible to one and the same body. Organic solids occur ander one of three conditions, viz.:- the crystalline, as | the diamond; the vitreous, as gla ; and the amorphous, or shapele , as clay, chalk, . But there are many bodies, any one of which, without undergoing a change in chemical composition, may yet appear under one of the above three conditions, with striking changes in physical and even chemical properties, while still retaining, so to speak, its chemical identity. Thus, ordinary white phosphorus may, by the application of heat,be converted into a hard red amorphous substance, which is its allotropic form. It is theoretically a umed that the particles of the body are in different states of molecular equilibrium in the two forms. [s. 21]