After being sufficiently pressed, the cakes are withdrawn, stripped of their cloths, and pared by the machine shown in Fig. 1037, which consists of 2 reciprocating knives moving above a table fitted with guides and gauges, and with a screw conveyer in the centre, for discharging the parings at one end. Two boy's attending the machine can pare 12-13 tone a day. The parings are taken under a very small set of edge-runner mill-stones, which automatically dis charge them, when sufficiently ground, into an ele vator leading to the kettle, where they are worked up with fresh seed. Larger edge-runners are very commonly used for crushing Egyptian cotton seed ; a set weighing 404 cwt. crush about 6 tons per 11 hours.
The ordinary method of liberating the coco-nut from the shell is to break the latter into two or more pieces by blows from a hammer, and to leave these exposed to the sun's rays for a few days, when the kernel contracts, and leaves the shell. Some yesrs since, Rose, Downs, & Thompson, of Hull, designed two machines for slicing and rasping the dried kernel, or copra, which, iu general construction, resembled gigantic mincing-machines. The slicing-machine worked well, and turned out a large quantity, but it was found to be of little value in practice, on account of the frequency with which stones and similar foreign bodies got mixed among the copra, and injured the knives. The rasping-machine also suffered in a minor degree from the same cause. Moreover, there was no real gain in using the machines, as they did not reduce the material to a sufficiently fine degree. The first produced thin slices, and the second rendered these granular only, like coarse sawdust, so that it was still necessary to pass the material through an edge-runner mill, and no perceptible difference was made in the amount of grinding required in this latter. Consequently, both machines have been abandoned, and the broken copra is thrown at once under edge-runners, and then pressed and dealt with much in the same manner as an ordinary oleaginous seed. The firm named estimate the average cost of the machinery adapted to a small mill capable of treating about 40 cwt. of copra daily, and making 24-25 cwt. of oil, and 15-16 cwt. of cake, as follows:— Engine, boiler, edge-runners, presses, pumps, gauges, "hairs," cisterns, pipes, nuts, bags, bagging, and_ all fittings complete, at about 10001. The same motive power will drive also the machinery
for preparing the fibre from the husk, costing about 150/. additional.
Not unfrequently, in order to extract the last traces of fat or oil from seeds and nuts, recourse is had to the solvent action of carbon bisulphide. This plan is adopted on a very large scale by Hey], of Berlin, and by Sevin, of London, for the manufacture of palm-kernel-oil; and so com pletely is the meal freed from all traces of carbon bisulphide and its attendant nauseous-smelling compounds, that it is much used for cattle-food, though less valuable for that purpose than the meal from simple expression, by reason of its deficiency in oil. -The residues from the extraction of olive-oil in S. Europe are dealt with in the same way, and made to yield an additional 2-4 per cent. of the so-called "pyrene " oil.
The method of employing carbon bisulphide may be illustrated by Figs. 1038 and 1039, showing respectively a longitudinal section and plan of Deitz's apparatus. It consists of extractors B, which are usually worked in couples alternately, and in connection with a still D, containing a steam-coil, and communi cating with a cooler C by means of a pipe e'. The pipe j leads from the cooler-worm to a recep tacle A for storing the bisulphide. The ex tractor B is also con nected with the cooler by the pipe e, and pro vided with suitable open ings for the introduction and withdrawal of the fatty matters. These latter are put into B between two perforated plates d d' ; bisulphide is pumped from A by the pipe /1 iu at the bottom of B. The bisulphide passes up through the mass, absorbs the fat present, and escapes finally by the pipe f to the still D. The admission of bisulphide is continued till a sample drawn off at k is free from fat. The biaulphide is then shut off, and steam is injected into the extractor through a perforated coil lying between the bottom and the perforated plate. The remaining bisulphide ie thus carried by the pipe f into the receptacle A. The fat-saturated bisulphide is distilled in D, by means of a steam-coil. The evaporated bisulphide liquefies in the cooler 0, and runs back into A for further use. Steam is occasionally passed through the fat, to completely free it from bisulphide ; and the clean fat is finally let out by the pipe i.