Condition of sparingly soluble substances in gels Part I. Silver chromate in gelatine

Abstract

Changes in the conductivity; colour of silver chromate in gelatine solution have been studied. It is observed that by suitable adjustment of the (i) temperature of the experiments; (ii) pH of gelatine; (iii) concentration of the reactants (AgNO₃and KCrO₄); (iv) amount of gelatine; the conductivity may (a) not decrease at all till the colour remains yellow; (b) decrease sometime after the colour change or (c) not change at all in spite of the colour change. In the end we would like to mention that our preliminary experiments on the precipitation of lead iodide in agar have shown that the (a) temperature ture at which the experiments are carried out; (b) pH of agar; (c) amount of agar; (d) concentration of the reactants [Pb (NO₃]₂ and KI) have a very marked influence upon the times when the colour change; decrease in conductivity take place as in the case of precipitation of silver chromate in gelatine.