a. Chem. [f. ARSEN(IC) + -IOUS.] Of the nature of, or containing, arsenic. In Chem. applied to those compounds in which arsenic combines as a triad, as Arsenious oxide or (less correctly) acid, common white arsenic.
1818. Accum, Chem. Tests, 145. Two or three grains of arsenious acid.
1873. Fownes, Chem., 481. Arsenious iodide.
1879. G. Gladstone, in Cassell’s Techn. Educ., IV. 272/1. Arsenious acid, the ordinary form in which arsenic is employed.
