How do we calculate Gold number of a colloid

· Gold Numberis defined as the minimum amount of lyophilic colloid in milligrams which prevents the flocculation of 10ml gold sol by the addition of 1 ml of 10%NaCl solution.It was first used by Zsigmondy.More is the gold number less is the protective power of the lyophilic colloid since it means that the amount required is more.The amount is taken in terms of weight in milligrams.

· The gold number of some colloids is given below.