The influence of the addition of electrolytes on the degree of dispersion of silver iodide hydrosol

The changes in the degree of dispersion of AgI hydrosols produced by reaction of AgNO₃ and KI with the addition of other electrolytes (1–60 min after addition of AgNO₃ to KI) were investigated by photometric methods. The results obtained suggest that in the process of rapid condensation (caused by a sudden increase in concentration to a value considerably higher than the critical one) colloidal particles do not form by continuous growth of individual nuclei but through disaggregation of loose and amorphous, i. e. thermodynamically unstable clusters of previously formed embryos. This disaggregation process, termed protopeptization by the authors in order to underline its analogy with the peptization process, increases in magnitude with the strengthening adsorption of potential-determining ions (protopeptizing agents) by the particles formed in the precipitation process.