[472]. Wimshurst’s condenser, requires no air pump. The exhaust comes down the vertical pipe, meeting the injection water from the side nozzle, causing sudden condensation and vacuum. The condensed water, &c., are blown out through the foot valves at each stroke.
[473]. Another form of ejector condenser in which the steam and water form a vacuum in the nozzle, and the water, &c., are discharged through a foot valve (not shown).
[474]. Tray cooler, or condenser; a series of water trays supplied from a tank above.
See Morton’s ejector condenser, which requires no air pump; Hayward’s exhaust condenser, which employs the water in suction pipe of a pumping engine to condense the steam. See Messrs. Tangye’s list. Water tube cooling coils are used for tuyeres and other hot surfaces.
Air-compressing and gas engine cylinders are water jacketed to carry off the heat of the compressed air or gas. Cooling by exposing a large surface to air is sometimes employed for exhaust steam on tram car engines &c., the apparatus consisting generally of numerous wrought-iron tubes or coils.
Section 26.—CONCENTRATING AND SEPARATING.
Sifting, riddling, and screening are treated of under [Section 72]. For concentrating ores many methods are in use, of which the water processes are the most important.
[475]. Circular revolving concentrating table. The lightest particles are discharged over the edge, and the heaviest remain in the centre.
The ordinary magneting machine, for separating particles of iron or steel from mixed borings, &c., consists of a series of magnets drawn through the material, and then through fixed brushes, which brush off the iron particles adhering to the magnets.