An ether ice-machine, made by Duvallon and Lloyd, of Birmingham, is shown in Fig. 831. It consists of an engine and air-pump, combined on the same bed-plate ; ts refrigerator; an ether - condenser ; a circulating - pump : and one or more ice-hoxes, according to the quantity of ice required. Iu the illustration, the air pump ie 9f in. in diameter, driven di rect by a steam engine, with 7k-in.
oyllnaers, the stroke being 21 in. The two cylinders are arranged in line, the two piston-rode being tottered to the cross head. Tho .guides consist of hollow angle-pieces, working on the corners of the square bars. The air-pump is double-acting. The connecting-rods, one at each side of the cylinder, work on crank-pins, inserted in discs keyed upon the main shaft, one of these discs being of considerable weight, so as to act as a flywheel. In the centre of the main shaft, is a pulley for driving overhead-shafting, from which the eireulating-pump and the agitator derive their motion. The two inlet passages of the air-pump, one at each end, are connected by a eopper pipe, from which brancheS another copper pipe, placing them in communication with the refrigerator. This is a cylindrical vessel, similar in construction to a multitubular boiler, covered with felt, and lagged with wood ; the tubes are made of copper, and riveted to brass end-plates. On the other side of the air-pump, the two outlet valves, connected in the same manner as the inlet valves, are placed in communication with the ether-eondenser, which is similar in construction to the refrigerator, but is of rectangular section, and has no copper shell. The tubes communicate at each end with metallic chambers, one of them acting as a receptacle for the air which finds its way into the condenser. The whole is immersed in a tank of wood, or of galvanized iron, through which a constant stream of water is made to pass, for cooling and condensing the ether vapour. A vacuum of about 254 in. is maintained by the air-pump in the refrigerator, vaporizing the ether at a low temperature. The absorption of heat due to this operation lowers the temperature of the strong brine, made to circulate, by means of the pump provided for that purpose, through the tubes and the ice-box. The latter is a tank of red deal, varnished inside, with partitions haying holes bored in them for allowing the brine to circulate slowly. Between the partitions, are suspended zinc moulds of rhombic form, varying in width according to the shape of bloeks of ice required, and filled with pure water. The
capacities and prices of this machine vary approximately from 120/, to make 3 cwt. of ice per 24 hours in England, to 2800/. to make 200 ewt. in the same time.
Another form of ether-machine, invented by A. Muhl, of Sau Antonio, Texas, is shown in Figs. 832 and 833. The pumps A are connected with the driving-shaft, as shown ; the condenser B contains a worm, which communicates, through the pipe on the outside, with the reservoir C below ; D E F are freezing-vessels of various forms. Each pump, as its piston rises, draws in from the freezing-vessels the ether which has been vaporized by the heat abstracted from the water or other liquids contained in them; as its piston descends, the vapour of the ether is forced into the worm of the condenser, and thence into the reservoir C, which it reaches in a liquid state ; it then passes into the freezing-vessels, where it is reconverted into vapour, and flows thence back into the pumps. The pumps have their induction pipes provided with suetion-valves (see A, Fig. 833), and their eduetion pipes with exhaust-valves.
The usual practice of making the worm, which is the principal agent by which the vapour is reduced to a liquid, of pipe of uniform diameter throughout is objeetionable, for the following reasons : If a small pipe is used, it is difficult to force the vapour through fast enough, and au unnecessary amount of power is consumed without effect; on the other hand, if the pipe is of the customary size (1-2 in. in diameter), only the layer of vapour immediately in contact, or nearly so, with its sides, is condensed, and the remaining uneondensed portion is discharged into the reservoir, there to be condensed at the expense of considerable power ; or is caused to enter the freezing vessel before condensation is effected, thereby defeating the object intended. To obviate these difficulties, the worm is composed of pipes of several different sizes. Several coils of large pipe, say 1i in. in diameter, are used at the point of entry, and are followed by coils of 1 in., I in., and in., by the last of which the exit is made. By this means, no resistance is offered to the passage of the vapour at its commencement, and all parts of its body are afterwards brought sufficiently near the sides of the pipe to ensure its condensation before the reservoir is entered. Thus power is saved, and the full effect of the freezing-apparatus is developed.