8.4.3 Take with a pipette volume analysis was placed in 250 ml Erlenmeyer flask having 5 ml grinding mouth stuffed it, and then added 50 ml of deionized water, 2-3 drops of phenolphthalein indicator, shake, with 1 mol/l NaOH colorless when dripping number of milliliters of NaOH consumption by a factor of 50 the number of points is aluminum polishing liquid