The plant for dealing with the sludge was moved from the old situation to new buildings specially erected for the purpose at Esholt, and the raw material is fed to the latter station through a special main. The sludge contains only 80 per cent. of water, the free water having been previously removed by settling. It is fed into the main by compressed air. Upon its arrival at the station the sludge is lifted, also by compressed air, into large vats, where it is heated by the waste steam from the engines of the power plant. In this heated condition the sludge passes into close-sealed vessels from which, still at a temperature approaching boiling point, it is forced by compressed air through the filter presses. Each of these presses, of which there are about 100 disposed in rows, contains 47 chambers, each 3 feet square. As already stated, the sewage of Bradford is heavily charged with grease resulting from wool-washing and other industries, and it is this heavy proportion of grease which renders the process so attractive. Moreover, by keeping the sludge in a heated condition during the pressing process the expression of the fatty content is more readily effected. From 40 to 48 hours are required to fill a press with residuum, that is to say this period of time must elapse before the whole of the available space within the press is occupied by the dry cake from which the grease has been expressed, by which time from four to five tons of sludge have been passed through. Each cake is 3 feet square by 1¹⁄₂ inches thick and weighs about 30 cwt. The grease and water which is driven out of the sludge is carried away from the presses into tanks. Here the water and grease are separated, the water to be re-discharged into the sewage, while the grease is led to the purification tanks. Subsequently the fat is either drawn off into barrels or is pumped into tank wagons for dispatch to the works where it is worked up into articles of commerce, including soap. The oil is found to yield three valuable products--olein, stearine, and pitch. The two last named enter extensively into the dressing of leather, as well as the manufacture of candles and as an insulator for electric cables, respectively.