Electrons in materials with flat bands move slowly enough for the particles to work together, but superconductivity might get a boost from “dispersive” bands, where the pairs travel more easily.
The low dispersive power of water masks, as Helmholtz has remarked, the imperfect achromatism of the eye.
The refractive and dispersive powers are not high, so that the cut stones display little brilliancy or “fire.”
There is little axis of direction in the energies put forth; they are largely dispersive and centrifugal.
Thus the dispersive power of flint glass and balsam are about equal, while that of crown glass is considerably less.
Dr Tyndall has shewn that a perfectly pure gas has no dispersive action.