Make measure: The products with Galla chinensis and Tannic as main material.After hydrolyze and acidification.  Formula: (OH)3C6H2COOH.H2O   M.W.: 188.14   Assay(%): 99.0 min   Loss on dry(%): 10.0 max   Burning remains(%): 0.1 max   Sulphate(%): 0.01 max   Chloride(%): 0.001 max   Tannic Acid test: 1.0 PPM   Cloud point: 10.0PPM   Color number: 150 Fan   Fe: 5.0PPM   Water in solubies: Clarifily