1. A negative ion causes the precipitation of positively changed sol and vice versa.
2. When the valency of ion is high, the precipitation power increased. So in cations the precipitation power order is Al3+ > Ba2+ > Na and in anions the precipitation power order is [Fe(CN)6]4- > SO42- > Cl-.
3. The precipitation power of electrolyte is determined by finding the minimum concentration required to cause precipitation of sol in 2hrs. This value is called flocculation value. The smaller the flocculation value, greater will be precipitation.