REFRIGERATION. 796 REFUNDING. reboiler is apijarent; the connection with the steam filter is utilized to automatically supply a small quantity of live steam to make up for any deficiency in exhaust steam. Other connections of the live-steam pipe to the' various apparatus are shown, which are used for cleaning out. The exhaust steam from the engine, and also for the two water ]nimps, passes beneath the first floor and rises tlnough the boiler-room and outside the main building to the third floor. Before it enters this it has a chance to escape through the j)ressure release valve if for any reason the vari- ous apparatus through which it passes should cause sufficient back pressure to impair the I)roper working of the engine. The exhaust steam passes first into the steam filter, thence into the lieater, where it heats the water which as we have already seen passes through this same heater on its way to the boiler. From the heater it passes to the condenser, thence to the reboiler. From this it goes through the condensed-water cooler to tlie deodorizer on its way to the cold-storage tank. From the cold-storage tank water is fed by a hose in any can whose ])lace may be rendered va- cant by the withdrawal of a can of ice. There we must leave the now thoroughly purified and distilled water in repose for some sixty hours. After this interval of time the can is lifted by the ice crane svisjjended from the carriage on which it is run down the tank-room to the sprinkler. In the sprinkler the can receives a shower bath of warm water and the ice when loosened drops out of itself and glides into the ice-storage room, the sprinkler in the meantime automatically put- ting itself into position to receive another can, thereby shutting oft' the supjily of warm water. The cake of transparent ice is allowed to remain in the ice-storage room until the time for the wagons to appear at the loading-platform ap- proaches, when it and as many of its fellow blocks as are required are withdrawn into the ante- room. A block of ice may pass straight through the ice-storage room and the anteroom to the loading platform, or it may remain a week or two in the storage. This ice-storage room is seen to be supplied with refrigerating pipes, so that if the demand is fluctuating the blocks will be pre- served intact, only so much being withdrawn into the anteroom as is necessary for immediate use. The following table shows the structural sizes and weights of blocks made bv the can svstem: WEIGHT OF BLOCKS 50 poundH, lOO 150 200 300 400 Size of pan. inches 6 X 12 X 26 8 X 16 X 33 8 X 16 X -42 11X22X32 11 X 22 X 44 11X22X B7 Time of freezing 20 hours 36 •• 36 " 60 ■■ 60 " 60 " The time of freezing is with 18° F. brine. ilANUFACTURiNG., In general it may be said that refrigeration is applied to all processes of manufacturing where it is desirable or necessary to have at some period a temperature below the normal atmospheric temperature. Some of these processes are brewing, chocolate-making, dyna- mite manufacture, india-rubber manufacture, su- gar-making, and chemical-making. The method of application varies with the process, but it is in general simply a modification of refrigerating processes as applied to cold storage and ice-mak- ing. There are numerous books on refrigeration, but the general reader will find the subject amply treated in Wallis-Taylor's Refrigeration, Cold Storage, and Ice-Making (New York, U)03). See LlCiUEFACTION OF GaSES. REFRIGERATION OF THE EARTH. That the earth is radiating more heat into space tlian it receives is evidenced by the fact that the temperature rises as the crust of the earth is penetrated. The flow of heat is alwajs from a liigher to a lower temperature, and consequently there is a constant conduction of heat from the interior to the surface of the earth, and a loss into space. The rate of flow of heat is dependent upon the conductivity of the material and the rate of rise in temperature. A substance is said to have the unit of heat conductivity when it will conduct the unit of heat the unit of distance in the unit of time through the unit cross-sec- tion, the temperature rising one degree for the unit length. In the present system unit con- ductivity corresponds to the transfer of enough heat to raise one pound of water one degree Fahr- enheit in one second through a bar of one square foot cross-section when the temperature falls one degree for one foot in the direction of flow. De- terminations of the increase in temperature as the cartli's crust is penetrated show that there is a marked variation from one locality to another, this variation depending upon the character of the rocks penetrated, the amount of disturbance they have undergone, and other local conditions. In the well at Wheeling, W. Va., which has a depth of 4,500 feet, the rise in temperature has been found to the 1° F. for each 75 feet of de- scent; in the well at Sperenberg, Prussia (depth 4,170 feet), the increase is 1° for 59 feet; and in the Schladabach well, near Leipzig (depth 5,740 feet ) , the increase is 1 ° for 05 feet. At other localities the rate varies from 15 to 200 feet for 1° F. Various causes have been suggested for this interior heat of the earthy but considering all the related astronomical and physical considerations it is most probable that it is a remnant of the original nebular heat which has not yet been dis- sipated, and which has been prolonged by the re- sults of the condensation from the nebulous state, lender the phrase 'age of the earth' is usually understood the time since the earth became prac- tically solid and the present method of cooling by conduction commenced. From data as to the conductivity of the rock materials and the rise in (em])erature it is possible to make certain estimates as to the age of the earth, and the latest and perhajis best is that by King, who, after an exhaustive discussion, concludes that it is about twenty-four million years and that the temperature at the time when convection ceased •was about 2000° C. (3600° F.). The amount of heat reaching the earth's surface from the in- terior in a year is sufficient to melt a layer of ice about one and a quarter inches thick, that is about one-thousandth of the amount reaching the earth from the sun. Consult article by King, in American Journal of Science (New Haven, 1893). REFUGE, City of. See City of Refuge. REFUNDERS. See Reawusters. REFUNDING (from refund. OF., Fr., refon- dre, to restore, pay back, remodel, from Lat. re-
