coagultion is the process by which the dispersed phase of a colloid is made to aggregate and thereby separtate from the continuous phase. The minimum concetration of an eletrolyte in milli-moles per litre of the electrolyte solution which required to cause the caogultion of colloidal sol is called coagution value . therefroe higher is the coagulatings power of effective ion, smaller will be the coagultion value of the electrolyte. coagultion value ` propto = 1/("coagulating power")` the coagulation values of differnt electrolytes are different . this behavious can be easily uderstood by Harby - schulze rule which states. the greater is the valency of the effective ion grreater is its coagulating power," which one had the highest coagulating powe?