When ohotoludine reagents is adeed to water and if free chlorine is present, what colour will be produced?

Ohotoluidine test enables both free and combined chlorine in water to be determined with speed and accuracy. The reagent consist of analytical grade ohotoluidine, dissolved in 10% solution of hydrochloric acid.When this reagent is added to water containing chlorine it turns yellow and the intensity of colour varies with concentration of gas. OT reacts with free chlorine instataneously but slowly with combined chlorine. Parks textbook of preventive and social medicine.K Park. Edition 23.Pg no: 715