For the extraction of oil on a larger scale, the apparatus shown in Fig. 13 is very suitable. It consists of two principal parts, the actual extracting vessel _E_, and the still _B_. The extracting vessel _E_ sits in a vat containing cold water, _W_, the arrangement being such that the heated water can be removed and replaced by cold. The still _B_ sits in a boiler, _K_, filled with hot water. The apparatus is charged as follows: The conical head _C_ of the extracting vessel _E_ is unscrewed and its connection at _H_ with the pipe _R_ loosened. The extracting vessel is then charged with the vegetable substance, the head _C_ replaced, and the connection with the pipe _R_ restored. The cocks _H_{2} and _H_{4} are then opened, and the required quantity of solvent is brought into the still. Both cocks are then closed, and the cocks _H_ and _H_{1} opened. The water in the boiler is then heated until the contents of the still commence to boil. The vapor of the solvent ascends through the pipe _R_; on entering the extracting vessel _E_ it is condensed, and after falling as a spray upon the material to be extracted, finally returns impregnated with volatile oil to the still _B_. Here the solvent is revaporized, and passes again through the material in the extracting vessel, while the extracted oil remains in the still. During the boiling of the solvent the extracting vessel must be suitably cooled by the constant admission of cold water. [Illustration: FIG. 13.] When extraction is finished, the cocks _H_ and _H_{1} are closed, and the cock _H_{2}, which is connected with a cooling worm, is opened. The solvent is then evaporated, and regained by condensation. The oil is discharged, from the still through a pipe in the bottom provided with the cock _H_{3}. The apparatus may also be so arranged that the still _B_ is connected with two extracting vessels which are used alternately, while the contents of one are being extracted the other is emptied and refilled. [Illustration: FIG. 14.]