Fig. 36.
When all the air has been expelled from the apparatus and the pores of the bones, the cock on the pipe, E, is closed. The cylinder, A, is then heated so that a pressure of a few atmospheres prevails in it. The vapors now act energetically upon the bones, the dissolved fat collecting upon the cylinder; the cock on the pipe, H, is then opened, and the superheated fluid discharged under high pressure into the distilling apparatus, J, and the solvent is distilled off from the fat by means of steam. The vapors of the solvent pass through the pipe, K, into the condenser, F, and from there back into the reservoir, C.
When the manometer on A indicates no pressure, the cock on the pipe, H, is closed and the cylinder, A, again heated, the pipe, E, being open, so that any solvent still adhering to the bones may escape to the condenser, F.
Fig. 37.
Figs. 37 and 38 illustrate Seltsam’s apparatus as improved by Th. Richter, whereby the operation becomes entirely free from danger, the vaporization of the solvent being effected by steam only, and the work is carried on continuously.
There are two extracting vessels, A and B, of thick boiler-plate, and provided with false bottoms, G, upon which the bones are placed, steam being admitted into the space between the true and false bottoms. The extracting vessels are surrounded by the jackets, C, and are further provided with the vacuum gauges, E, and the air-cocks, F.
There are, in addition, two other vessels, H and J, which contain water, a vessel, K, for the solvent, and an air-pump, L. The operation is carried on as follows:
Fig. 38.