Stability of Lyophobic Colloids. Part-XIX. Applicability of the various modifications of Wetham's rule for the hydrophobic sols in a medium of varying dielectric constants of the dispersing medium

The applicability of the relations proposed by Verwey and Overbeek and by S. Ghosts, et al. for the precipitation value or mono-, bi-, and trivalent coagulating ions have been examined here for the positively charged hydrous ferric oxide sols obtained by varied methods and containing different amounts of free peptis­ing hydrogen ions and at the varying dielectric constants of the dispersing medium. It has been concluded that the former relation having a number of theoretical evolutions restricts its applicability over large range of coagulation studies. The relations suggested by Gbosh, et al- represents the data more precisely but has a limited application in as much as it does not consider the specific effect of ions and of the dispersed material, which factors have been also ignored by Verwey and Overbeek. However, it appears from our experimental data that the ratio of the precipitating values generally diminish with the decreasing stability of the sols of hydrous ferric oxide studied here