The cylinder _A_{2} is, however, still filled with the solvent and material saturated with it. To remove the solvent, the discharge cock _K_{2} on the bottom of the cylinder is opened, which communicates with the discharge pipe _J_, through which the bisulphide of carbon is conducted into a reservoir. The discharge is promoted by opening the cock _M_{2}, connected with the pipe _L_, and the admittance of compressed air, which displaces the liquid solvent. After the flow of the latter has ceased, the steam cocks on the jacket _O_{2} and the cylinder _P_{2} are opened under constant admission of air and simultaneous introduction of steam through the pipe _N_ into the upper part of the cylinder. The solvent (bisulphide of carbon) converted into vapor by the heat, is conducted together with the aqueous vapor, by the admission of air through the cock _K_{2}, the pipe _J_, and a cooling pipe placed between the extracting vessels and the reservoir, and collected in a reservoir to be re-used. On account of the great volatility of bisulphide of carbon, considerable loss would, however, be incurred by the above-mentioned admission of air. To avoid this, the reservoir serving for the reception of the condensed bisulphide of carbon and aqueous vapor is closed, and connected by a pipe with a long, narrow, horizontal cylinder half filled with oil, and provided with a fan-shaft. The vapors of bisulphide of carbon entering the cylinder from the reservoir are absorbed, together with the air by the oil, the surface of which is constantly agitated by the fan-shaft, while the air, rendered entirely inodorous, passes out at the other end. The bisulphide of carbon is finally separated from the oil by distillation and again used. After the cylinder _A_{2} is sufficiently steamed, it is emptied and again charged with material and connected with the cylinder _A_{1}; while the other cylinders undergo the same manipulations described above. [Illustration: FIG. 15.] The saturated oil solution is subjected to distillation, which is readily effected in Heyl's apparatus, Fig. 15. The lower part of the still _A_ of boiler plate is surrounded by the steam-jacket _B_, into which steam is admitted through _C_ and the condensed water discharged through _D_. The concentrated oil solution runs from a reservoir, standing at a higher level through the pipe _E_ into the still, the admission of a sufficient quantity being indicated by the gauge _F_. The bisulphide of carbon brought to the boiling point (114° F.) by the steam introduced into the jacket, vaporizes quickly; the vaporization being still more accelerated by revolving the stirrer _H_, by means of the crank _G_. The vapors of bisulphide of carbon escape through four openings in the upper part of the still, into a capacious worm, the lower part of which enters, under water, a reservoir.