Fig. 35.
Water is now admitted through the pipe m to the space in the vessel below the diaphragm d, and the cocks of the outlet-pipes n n′ are opened.
The water permeates the material, passes upward through the same, and carries with it the hydrocarbon, the latter having a tendency to rise with the water.
As the water, and whatever hydrocarbon accompanies it, pass through the upper diaphragm, b, the hydrocarbon will at once rise to the surface, and will pass through the upper outlet-pipe, n, into any suitable receptacle, the water passing off through the lower outlet-pipe.
If this mode of separating the hydrocarbon from the water is practiced, the admission of water to the vessel should be such in respect to the outflow that the liquid will remain at or near a uniform level, that is, the surface of the liquid should bear the relation shown in the drawing to the upper outlet.
The water and hydrocarbon, however, may be drawn off indiscriminately into a suitable receptacle, and then separated by decantation; but it is advisable in all cases that the water should extend above the mass of material in the vessel, so that the hydrocarbon can at once rise to the surface as it escapes from the substance.
When the material is of such a character as to be closely packed and not easily displaced by the upwardly-flowing water (and this is especially the case with seeds which have been treated with hydrocarbons), it is necessary to agitate the mass, so that the water can gain access to every part thereof. This agitation the inventor prefers to effect by air under pressure introduced through a pipe, p, although mechanical appliances may be used for the purpose.
It will be understood that the process may be conducted in a vessel separate from which the substances have been treated with hydrocarbon. A vessel similar to that shown, for instance, but without the coil and pipes, D D´, may be used, and may be furnished with trunnions (shown by dotted lines) and adapted to bearings, so as to be easily tilted when its contents have to be removed; or the vessel may have an opening near the lower diaphragm for the withdrawal of its contents, a suitable detachable door being adapted to the opening.
F. Seltsam’s apparatus. In this process the solvent is boiled with the bones, previously coarsely crushed and the dust sifted out, in a strong closed vessel, so as to obtain a higher temperature, greater penetration and avoidance of loss. The vapor ascending condenses in the pores, extracts the fat and collects under the false bottom as a layer of solution which is subsequently distilled. The apparatus is shown in Fig. 36. The cylinder, A, is capable of withstanding a pressure of 10 atmospheres, and serves for the generation of steam and as an extracting vessel. It is filled with bones and hermetically closed. The required quantity of solvent is then brought by means of the pump, B, from the reservoir, C, through the pipe, D, into the cylinder, A, and the latter is heated. The vapors formed force the air through the pipe, E, into the condenser, F, where any vapor which may be carried along is condensed and passes through the pipe, G, back into the reservoir, C.