through the interstices in a direction opposite to that of the water falling from the top. Under these conditions, the gas is cooled, gives up the ammonia and the dust which it may still contain in suspension, and is conveyed to the engine either directly or after passing through certain purifiers. Care should be taken to place the
pieces of most regular shape along the walls, so that the unevenness of their surfaces may not form upward channels along the shell, through which channels the gas could pass without meeting the wash-water.
Fig. 125.—Otto Deutz scrubber.
Fig. 126.—Winterthur scrubber.
Fig. 127.—Benz scrubber.
The material most commonly employed in washers is coke in pieces of from 21⁄2 to 31⁄2 inches in size. This material is cheap and is very well suited for retaining
the impurities of the gas. The largest pieces of coke should be placed at the bottom of the washer, and smaller pieces should form at the top a layer from 6 to 8 inches deep. In this manner the water is distributed more evenly and the gas is more thoroughly washed. Blast-furnace coke is best suited for this washing, as it is more porous and less brittle than gas-works coke. It