ALLOTROPY (Gr. liXXor, other, and rpo7ros, manner)  , a name applied by J . J . Berzelius to the property possessed by certain substances of existing in different modifications . Custom has to some extent restricted its use to inorganic chemistry; the corresponding property of organic compounds being generally termed isomerism (q.v.) . Conspicuous examples are afforded by oxygen, carbon, boron, silicon, phosphorus, mercuric oxide and iodide .