Many attempts have been made to clear pipes thus filled with FIG. 320.-Two Single Boilers Doing Work of Double Boiler. ally more satisfactory to replace the filled pipe with new pipe Acids act on such deposits, as also caustic soda, but they con- Special patented devices for attachment to the range connection may be procured, which are claimed to prevent the choking of the pipes with lime. It would seem, however, that these various devices and recipes were not along the proper lines, and that a much better plan would be to prevent the entrance of the impregnated water into the range connection, where most of the trouble from accumulation of lime occurs. Fig. 321 illustrates a method of this nature. cording to this plan, two attic tanks are used, a small tank for rain water and larger tank for the hard water of the natural supply. It will be noted that no range boiler is used. Ac A down supply line from the rain-water tank is connected directly to the water front, the flow pipe from which is carried up to the hard-water tank and connected to a heating coil located in the latter. After passing through this coil, the water passes back to the rain-water tank. This constitutes a complete system of circulation for the heating of the contents of the hard-water tank by means of the coil, the work being done by water free from lime, and thus avoiding the deposit of lime in the range connections. From the hard-water storage tank a line of hot-water supply is taken down to the various fixtures. It is an excellent plan to place blocks of limestone on the heating coil in the hard-water storage tank, as the lime in the water will deposit on such blocks in preference to the piping or sides of the tank. The use of these blocks will therefore aid greatly in keeping the tank and piping free of lime. If limestone is not at hand, oyster or clam shells will do the work. Shells placed in a tea kettle in which hard water is used will prevent the accumulation of lime inside. While the method just described is the most effective one that has yet been suggested, there are two objections connected with its use that should be mentioned. In the first place, if the hard-water storage tank is open it cannot be made to heat to so high a temperature as the range boiler, owing to the escape of heat from the exposed surface. In the second place, more or less steam must inevitably escape into the air, and in many cases this feature would be objectionable. Without doubt, however, the tank could in most cases be heated to a sufficiently high temperature for all ordinary purposes. There is no reason, however, why this tank cannot be sealed over, with a vent taken through the roof, which would in a large measure free it of its objectionable features. Another method of preventing lime deposit is to use a range boiler having a coil, the water front being connected direct to the coil, but not otherwise connected to the boiler. The water front should be supplied with rain water, and from the high point on the flow pipe an expansion pipe should be carried to the tank. CHAPTER XXVII THE WATER LIFT AND ITS APPLICATIONS As generally considered, the water lift finds its principal application in city work, but may also be used to great advantage in the country, and in connection with institutions, manufacturing plants, etc., that have their own private systems of water supply. In Fig. 322 is to be seen a sectional view of a successful type of FIG. 322. Sectional View of Water Lift and Auxiliary Valve. water lift, and of its auxiliary valve. Owing to the position of the auxiliary valve, it is impossible to show it in a sectional view of the water lift, and therefore it is shown in a separate view. Fig. 323 shows the connections for the water lift more clearly than the sectional view does. The water lift is operated by water pressure, and its action may be compared to that of the steam |