You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Which one of the following method is used for the estimation of Chlorine demand of water? and explain in detail?
Estimation of chlorine demand of water (or dose of bleaching powder required for disinfection of water) is done by 'Horrock's apparatus'. Chlorine demand of water: is the amount of chlorine that is needed to destroy bacteria and to oxidize all the organic matter and ammoniacal substances present in water. Is the amount of chlorine added to water minus amount of residual chlorine remaining at the end of specific period of contact (1hr). - Also remember, Free chlorine level in water is estimated by CHLOROSCOPE.