The capacity of the lyophilic colloid in protecting a lyophobic colloid is measured in terms of Gold Number, introduced by "Zigmondy".
Gold Number : " It is the number of milligrams of lyophilic colloid that is to be added to 10 ml of standard gold sol to prevent its precipitadon by the addition of lml of a 10% sodium chloride solution”.
Lesser in the gold number the greater is the protecting capacity. Gold number of a few colloids are given below.
Starch =25
Gelatin =0.005-0.01
Albumin =0.1-0.2
