What does "dialytic" mean?

Dialytic: Having the quality of unloosing or separating. Clarke. Dialytic telescope, an achromatic telescope in which the colored dispersion produced by a single object lens of crown glass is corrected by a smaller concave lens, or combination of lenses, of high dispersive power, placed at a distance in the narrower part of the converging cone of rays, usually near the middle of the tube.