Since the introduction of the so-called hypochlorite treatment of waters, in 1908, many complaints have been made by reason of using an excess of there-agent. Many difficulties have been encountered in properly mixing this re-agent with the water supply to be purified, leading to the complaints above mentioned. To avoid this trouble and to have a more controllable supply, efforts have been made to use liquid chlorin instead of the hypochlorite. Chlorin gas is easily liquefied and kept in strong cylinders in a liquid state in the same manner as is practised with carbon dioxid. Liquid chlorin has been used with good effect in combatting typhoid fever in the waters of Lockport, Tonawanda and Buffalo, New York, Chicago and Milwaukee. The use of it is easily controlled and it mixes with great facility and evenly with the whole water supply. Liquid chlorin does not remove turbidity nor color from water, and therefore it is not a complete substitute for the ordinary forms of precipitation and filtration.