ABSORPTION 1CH-MACHINES can be built and operated at less cost than the superior types of compression apparatus, and it is further claimed in favor of the former that it is easier to pump the water of ammonia used in that machine than to pump the highly elastic, gaseous ammonia used in a compression machine. The comparison in the sizes of the two pumps is stated to be as 1 is to 500 in favor of the absorption process, not counting the additional trouble of keeping a gas-pump in good working order, but this is probably an exaggeration. Upon the other hand, it is asserted that out of the many ice-making plants which are known to have been abandoned, particularly in the South, the majority consists of absorption machines. The objections raised to the absorption principle are that there is not the same economy of fuel or water ; that the action of the weak liquor will eat out pipe-work, necessitating frequent renewals of the pipe system; that it is impracticable to keep the ammonia in the evaporator-coils anhydrous for any considerable length of time, because the driers will become moist, and that expansion and contraction strains and opens the joints in the still and apparatus, and renders the plant wasteful of ammonia. Be alt this as it may, this system has steadily increased the number of its advocates, and ice-manufacture is, com mercially and mechanically speaking, making substantial headway.
In one of the latest improved absorption ice-maehines, the ammonia-boiler contains in its lower half ends for heating water of ammonia, and its upper half contains the The latter consists of a number of cast-iron pans bolted together, and arranged to form a zigzag passage through them, for gas passing up and rich liquor leissing down. The extreme upper end of the boiler is connected by a pipe with the upper end of a coil in the condenser, which consists of an oblong iron tank open at the top. containing one or more coils immersed in water for condensing the ammonia. The outlets of the coils are connected with a collector, made up of a cylindrical reservoir closed at both ends, and having, all external glass gauge to indiente the height of liquefied gas inside. This collector is connected al its bottom by n pipe with gas-exehanger, which consists of a closed cylinder containing a coil, the inlet of which is connected with the pipe from Hie collector. A pipe having a regulating-valve connects this
coil with it manifold, to which is again connected a coil Iving in a wooden tank. calked water tight 011 the bottom and sides, and surrounded with a heat-non-condueting substmICe ; this is callett the " bath." This last coil is jointed at the tipper end with the manifold. The tank contains a solution of salt and water. Partly hnmersed in this brine are the cans containing the distilled water, which is to be converted into ice. A lattice-work covers the top of the • bath, admitting the cans between its spaces, and a separate lid is also used. The outlets at the bottom of these last-named coils are connected by another manifold which is in turn, con nected with the gas-exchanger. The outlet of the gas-exchanger is at the top, and is connected by a pipe with a coil in the distilled-water tank, which is round, of wrought iron, and closed at both ends ; internally, there are two coils. The outlet of the coil connected with the gas exchaiwer is connected with the absorber, which is a closed cylinder, containing one or more coils, through which circulates river or well water. The pipe from the distilled-water tank enters this absorber at the top, and extends clown to within a few inches of the bottom. There is an outlet-pipe at the bottom, which extends to the bottom of the poor-liquor exchanger; this is also a closed cylinder, and contains a coil for partially cooling the poor liquor drawn from the ammonia-boiler. The outlet of this coil is connected by a pipe with the cooler, which is an iron tank open at the top, containing water and a coil immersed therein; the ab sorber is connected with this coil by a pipe haying a regulating-valve. The inlets of the coils of the ammonia-boiler have a pipe connection with the steam-boiler, and the outlets are con nected to a heater consisting of a closed cylinder containing a coil for heating feed-water for the steam-boiler, and condensing steam to make ice. The top of the heater is connected by a pipe to the top of the distilled-water tank. Gauges are employed for indicating the steam pressure, ammonia boiler-pressure, and pressure or vacuum in the absorber.