518 MODERN GASWORKS PRACTICE
periphery. The balis vary from 1J inch.es to 2 inch.es in diameter, according to the size of the machine. They are made from hard, sycamore, and each has a hole, half an inch in diameter, bored through the centre. The machine is so arranged that the gas is caused to travel in contact with the balls, and thus becomes thoroughly subjected to the action of the liquor. In some cases a series of perforated. buckets have been fixed upon the cases, and so arranged that they pick up the liquor and discharge it over the balls when at the top of their circular course.
Fig. 322—Holmes’ Washeb-Scbubbbb.
Centrifugal Washer-Scrubbebs
Centrifugal washer-scrubbcrs are of comparatively recent introduction, and differ considerably from the machin.es previously described. First, they are essen-tiaüy of the vertical type, ha ving a series of vertical compartments through which the gas passes in sequence. The best known. in this country is that made by Kirkham, Hulett and Chandler, illustrated in Fig. 324. It consists of a cylindrical cast-iron. vessel divided into a number of chambers through wliich passes a vertical shaft. To this shaft are attached specially shaped trays, which, revolving at a speed of about 100 to 150 revolutions per minute, lift up and spray the washing liquid so as to bring it into intimate contact with the ascending stream of gas. The number of chambers varies from two to ten, according to the purpose for which the apparatus is required ; but, in general, the machines composed of a small number of chambers are employed for naphthalene washing, spraying an oil instead of gas liquor. The construction of the trays is best seen from Kg. 325. Each tray