Gold number of haemoglobin is 0.03. Hence 100 ml of gold sol will require haemoglobin in what quantity so that gold is not coagulated by 10ml 10% NaCl solution
Gold number is the minimum amount of protective colloid in milligrams which prevents a color change from red to violet of 10ml gold sol by the addition of 1 ml of 10%NaCl solution.
10 ml of sol needs 0.03 mg of haemoglobin (as per gold no.) therefore 100 ml of sol would need =100 ml × 0.03 mg/10ml
=0.30 mg haemoglobin.