Gold number

Gold Number is a term used in colloidal chemistry. It is defined as the minimum amount of protective colloid in milligrams which change the colour from red to violet of 10ml gold solution by the addition of 1ml.10%NACL solution Physical Pharmacy, page 96</ref> Gold Number is a term used in colloidal chemistry. It is defined as the minimum amount of protective colloid in milligrams which change the colour from red to violet of 10ml gold solution by the addition of 1ml.10%NACL solution Physical Pharmacy, page 96</ref> Coagulation of gold sol is indicated by colour change from red to blue/purple when particle size just increases. More is the gold number, less is the protective power of the lyophilic colloid since it means that the amount required is more. It was first used by Richard Adolf Zsigmondy. The amount is taken in terms of weight in milligrams. The gold number of some colloids are given below.