Chlorine demand is measured by which of the following apparatus?

Chlorine demand is the amount of chlorine that is needed to destroy bacteria and to oxidize all the organic matter and ammonium present in water. The chlorine demand of water is estimated by the Horrock's apparatus. It is a testing apparatus used to calculate the dose of bleaching powder that will be required in order to disinfect the water. According to this apparatus about 2.5 grams of good quality bleaching powder will disinfect 1000 litres of water. Ref: Park's Textbook of Preventive and Social Medicine 19 th edition; pages 576 - 578; 587 - 588