Additionally, Zaiser and LaMer report an approximate power law rate expression, but corrections were later made by Dinegar, Smellie, and LaMer 21 and mechanistically explained by Davis. The corrected expression for the rate depends on the second acid dissociation constant of thiosulphuric acid, which were later determined more accurately by Page. I fit Zaiser and LaMer's absorbance data to the corrected integrated rate expression and use this to convert reported initial concentrations to rates at the peak of supersaturation and find an appreciable difference compared with the predictions of the power law expression (up to 36% -see S3).