Optical Absorption and Color Caused by Selected Cations in High‐Density, Lead Silicate Glass

The effect of impurities on the color of dense flint glass was investigated by comparing the optical absorption caused by cations in Na 2 O·3SiO 2 ·2PbO glass, in Na 2 O·3SiO 2 ·2PbO:1 wt% Sb 2 O 3 glass, and in Na 2 O·3SiO 2 glass; all three are colorless when of high purity. Of 11 colorants, only vanadium colored both lead glasses less intensely than the Na 2 O·3SiO 2 glass. Factors that make the lead glass more susceptible to coloration are higher oxidation states of polyvalent cations, larger absorption cross sections of polyvalent cations, and the tendency of prominent absorption bands to be closer to the wavelength at which eye sensitivity is a maximum.