oakes to be made where 4 8-1b. cakes were for merly made, and (2) to ensure uniform size and weight, and uniform density or consistence throughout. The cakes are removed from the moulding-machine, and put into the press F, 3 or 4 of which are required to each moulding-machine. The pressure is applied either by means of hydraulic pumps, or by a high-and low-pressure accu mulator; but unless extreme care is used with the latter, it gives too rapid a pressure, squirting out the seed at the side of the plates, and exercising a destructive effect upon the cloth em ployed. The pulsa tion caused by the pumps working di rectly to the press cylinder is more akin to the action of a wedge, and seems to extract the oil better than the dead pressure given by the accumulator. If the latter is used, a small oylinder may be applied to give the preliminary pressure in the moulding-machine, in lieu of a cam. After remaining under pressure about 25 minutes, the cakes are withdrawn, and after being stripped of the cloth, are pared by the machine H, which completes the manufacture of the cakes. The parings fall under a very small pair of edge-running stones J, which automati cally discharge them, when sufficiently ground, into an elevator conducting to the kettle, where they are worked up with fresh seed. In a mill with 4 presses, 2 men and a boy in the press-room can make 6 tons of cake in 11 hours, a rate of production requiring 6 men by the old process. The saving in steam-power is about 30 per cent., chiefly due to the absence of the heavy edge-runners, which also effects an economy of space. About 2 per cent. more oil is extracted, and the cakes are improved in appearance by not having the structureless texture caused by the trituration of the seed under edge-runners.
Having described the general routine of the process, some details may be added concerning the working of the several machines. The roll-frame Fig. 1032, consists of 4 or 5 chilled-iron rolls, each 3 ft. 6 in. long by 16 in. in diameter, placed one above the other. These rolls are used for crushing all the seed that passes through one set of presses making 5i-61 tons linseed-cake per spell of 11 hours. The seed passes into the hopper in the usual manner, and is distributed to the crushing-rolls by a fluted feed-roll the same length as the crushing-rolls, placed at the bottom of the hopper. When the seed passes the feed-roll, it falls on a guide plate that carries it between the 1st and 2nd roll. After passing between these rolls and being partly crushed, it falls on a guide-plate on the other side, which carries it back between the 2nd and 3rd rolls, where it is crushed more fully. It then falls on another guide plate, which carries it between the 3rd and 4th rolls, where it is ground more fully ; then it falls on a 4th guide-plate, and is conveyed between the 4th and 5th rolls to receive the finishing touch. It is thus crushed four times.
The kettle is shown in Fig. 1033, which represents one capable of heating sufficient seed to keep 4 16-plate presses occupied, or to make 6 tons of cake per 11 hours. It is steam-jacketed and
furnished inside with a damping-apparatus. The inside diameter is 5 ft., and the depth 2 ft. 6 in. The seed introduced is kept iu motion by the stirring-gear, and when sufficiently heated and damped, is withdrawn by the box A in quantities to form one cake, and transferred at once to the moulding-ma chine, attached or separate.
This machine is illustrated in Figs. 1034, 1035. Its purpose is to measure the quantity of seed required to make each cake, to shape it as required, and to press it so much, without extracting any oil, as will enable the greatest number of cakes to be put into the press. The measure of seed is placed on a strip of woollen cloth, spread upon a thin iron tray, sliding on the guides B ; the bottomless hinged mould C, having the exact shape of the intended cake, is closed upon it, and the measure A (Fig.1033), which is also bottom less, is drawn over guides in the upper sur face of the mould C, thus accurately dis tributing the seed. The mould is next thrown upon its hinge (Fig. 1034), and the ends of the strip of cloth are folded over the seed, the thickness of which is about 3 in. The thin iron tray, with the mould of seed upon it, is then pushed along the guides B, beneath the die D. This action gives motion to a cam, shown.
above in the illustrations, but which may be placed beneath if necessary. This earn brings down the die, and compresses the mould of seed to a thickness of 1i in. ; its revolutions are so timed that the seed is under pressure long enough (about minute) to let the workman have another cake ready.
When the die of the moulding-machine rises, the cake and tray are removed and placed in the press (Fig. 1036), the tray being withdrawn. The plates of the press are slightly thickened towards the edges, and bear the name of the manufacturer in reverse. The press is suitable for extracting oil from linseed, rape-seed, cotton-seed, hemp-seed, niger-seed, sunflower-seed, gingclly-seed, castor-seed, ground-nuts, coconuts, olives, &o. It is made in various sizes. The No. 1 double press (not shown) is furnished with 4 cake-boxes, suitable for making 4 tapered cakes at one pressing, each about 2 ft. 5 in. long, by 10i in. wide at one end, and 7i in. at the other, when using linseed, 48 lb. of Bombay seed being required to charge the press, and giving a cake weighing about 8 lb. ; the maximum and minimum weights of its charges are 60 lb. and 40 lb., of the cakes, 13 lb. and 6i lb. The charges vary from 3 to 6 an hour, being 4 for cotton-seed and 5 for linseed ; most other seeds are worked the same as linseed, but rape and gin gelly are worked twice. By using 2 presses for the first time and 3 for the second, 3 presses will crush as much seed as 5. These presses are made of a capacity to take 270-320 lb. seed at a charge, giving cakes of 9-15 lb., and requiring 30-45 minutes for the operation. In all these presses, the hair wrappers, weighing some 26 lb., used in the old process, are Dispensed with.