Gold number is a way to measure the protective power of a lyophilic colloid in order to protect a lyophobic colloid.
Gold number is inversely proportional to protective power of a lyophilic colloid.
By definition, gold number is the minimum amount(in mg) of a given protective/lyophilic colloid that needs to be added in 10ml of standard Au sol to ensure no coagulation takes place upon addition of 1ml of 10% NaCl(peptizing agent).
For instance, Gold number of gelatin is around 0.005 while that of starch is 25,thus making the former the best protective colloid while the later is the worst.
Final Answer:
Hence, gold number is a method to quantitatively determine and compare protective power of different lyophilic colloid.
