Adsorption of Dyes to Silver Halides: a Correction

Abstract

IN a letter on this subject (NATURE, Dec. 25, p. 913), the number of dye molecules adsorbed at saturation to the surface ions of silver bromide crystal was given as about 1 dye molecule to 20 ions at pH 5.5. An error in the calculations has been found, which shows that the adsorption should be just ten times as great, namely, 1 dye molecule to about 2 ions of the lattice surface. Inasmuch as the dye adsorption increases with increased pH, it is probable that the limiting adsorption density occurs at the formation of a complete monomolecular layer. It may be possible to test whether the maximum sensitising effect is reached before this layer is completed.