The use of liquefied chlorine for the disinfection of water was first proposed by Lieutenant Nesfield[1] of the Indian Medical Service. He stated that: "It occurred to me that chlorine gas might be found satisfactory ... if suitable means could be found for using it.... The next important question was how to render the gas portable. This might be accomplished in two ways: By liquefying it, and storing it in lead-lined iron vessels, having a jet with a very fine capillary canal, and fitted with a tap or a screw cap. The tap is turned on, and the cylinder placed in the amount of water required. The chlorine bubbles out, and in ten to fifteen minutes the water is absolutely safe, and has only to be rendered tasteless by the addition of sodium sulphite made into a cake or tablet.... The cylinders could, of course, be refilled. This method would be of use on a large scale, as for service water carts." The first _practical_ demonstration of the possibilities of this method was made by Major Darnall[2] of the Medical Corps, United States Army, in 1910. Chlorine was taken from steel cylinders and passed through automatic reducing valves which provided a uniform flow of gas for the water requiring treatment. A uniform flow of water was maintained through the mixing pipe and so secured a uniform dosage. This apparatus might be considered as the forerunner of the various commercial types of machines that were developed later and which are being so extensively used at the present time. A working model, having a capacity of 500 gallons per hour, was erected at Fort Myer, Va., and was operated on water that had been treated with alum but had received no further purification. Despite the presence of the flocculated organic matter, satisfactory purification was obtained with 0.5 to 1.0 p.p.m. of available chlorine and no taste or odour was imparted to the supply. From the results obtained at Fort Myer, and Washington, D.C., Darnall concluded that "In general, it may be said that with an average unfiltered river water such as that of the Potomac, about one-half of one part (by weight) of chlorine gas per million of water will be required. For clear lake waters three-tenths to four-tenths of a part per million will be sufficient." A Board of Officers of the War Department examined the results and reported (June, 1911) "That the apparatus is as efficient as purification by ozone or hypochlorite and is more reliable in operation than either.... That it could be installed at a very low cost and that the cost of operation would be very slight." In June, 1912, Ornstein experimented with chlorine gas, obtained from the liquefied gas in cylinders, for sewage and water disinfection but his method differed from Darnall's in first dissolving the gas in water and feeding the solution to the liquid to be treated.