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By optics or sight; with reference to optics. Optically active, Optically inactive (Chem. Physics), terms used of certain metameric substances which, while identical with each other in other respects, differ in this, viz., that they do or do not produce right-handed or left-handed circular polarization of light. -- Op…

By means of ocular view, or one's own observation. Sir T. Browne.

different properties in different directions; thus, crystals of the isometric system are optically isotropic, but all other crystals are anisotropic.

to each other as to be seen separate only by means of a telescope. Such stars may be only optically near to each other, or may be physically connected so that they revolve round their common center of gravity, and in the latter case are called also binary stars. -- Double time (Mil.). Same as Double-quick. -- Double…

Not active; inert; esp., not exhibiting any action or activity on polarized light; optically neutral; -- said of isomeric forms of certain substances, in distinction from other forms which are optically active; as, racemic acid is an inactive tartaric acid.

A variety of sugar, found in certain plants. It is optically inactive.

g the same constitution (expressed by the name ethylidene lactic acid), but the latter is optically inactive, while sarcolactic acid rotates the plane of polarization to the right. The third acid, ethylene lactic acid, accompanies sarcolactic acid in the juice of flesh, and is optically inactive. -- Lactic ferment, an…

Optically; as through a glass. [R.] You see them perspectively. Shak.

ed by all crystals except those of the isometric system. A uniaxial crystal is said to be optically positive (like quartz), or optically negative (like calcite), or to have positive, or negative, double refraction, according as the optic axis is the axis of least or greatest elasticity for light; a biaxial crystal is s…