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CANE SUGAR.sugar in the cake is not, as a rule, effective. A rather different system is nowusually followed. In Fig. 153 are shown, in section, the types of plate used.One plate is solid, and the other consists of a frame only, a. The solid andhollow plates are placed in the press alternately. At the angles of both frameand press are the circular openings b and c, so that in this press there are twoconduits, that at b is for the passage of the juice, and that at c for the washingwater. The channel h, in the hollow plates, conducts juice to the interior ofthe press, and in the solid plates there is a similar channel i. A light joint ismade along the conduits by placing indiarubber rings, d, in the closed openingsb or c, as the case may be. At g in the solid plate is an opening communicatingwith the cock f. Bags without openings are hung over the solid plates,but do not cover the conduits b or c. Scums being forced into the press bythe conduit b, pass through the channels h and fill the spaces between the twosolid plates formed by the hollow plates. The clear juice passes out through.g, the scums being caught between the bags. To wash the cake, water isforced through the conduit c, and passes through the cake in a directionopposite to that by which the juice travelled. The advantage of this type ofpress over the central feed press is that the washing is more effectively performed,and that the bags not needing to be cut have a longer life.Capacity of Filter Presses.—To filter scums an allowance oftwo square feet of filtering area for every gallon per hour is necessary, andtaking the scums as 10 per cent, of the volume of the juice, two square feetof filtering area should be allowed for every 10 gallons of juice per hour; thisis a minimum allowance and should be increased at least 25 per cent, to allowfor time lost in changing cloths, &c. "Where, as now is often the ease, thescums are thoroughly washed, or are re-pressed, a greatly increased capacityis called for.276