The closer pH approaches to neutral, the more rapid silicic-acid gelatin rate becomes, and the higher alkalinity or acidity is, the relatively slower silicic-acid gelatin rate becomes. Monomer and low polymer turn into higher polymer during the activated process, and high polymer is the predominant form of silica in activated products, and its amount is above 80%. Activated products molecular weight is 9.3 × 10³ by gelatin chromatogram and it is a kind of particulate anionic inorganic polymer, and its optimal dose is about 1 mg/L SiO₂ in the Huangpu River raw water treatment. It can reduce averagely about 28.2% of coagulant dose and maintain stable turbidity of settled basin outlet.