Meaning of flint glass

flint' glass"

Pronunciation: [key]
— Optics. Optics.
  1. an optical glass of high dispersion and a relatively high index of refraction, composed of alkalis, lead oxide, and silica, with or without other bases, sometimes used as the diverging lens component of an achromatic lens.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.