Perfumes and their preparation

by George William Askinson

Fig. 26.

The solvent is admitted to the reservoir R in the lower part of the condenser B through the tube indicated in the figure. The material to be extracted having been filled into the cylinder A through the manhole, the apparatus is closed. The cold water is admitted to the condenser by opening a faucet. The three-way cock shown in Fig. 25 is so placed as to open a communication of the overflow tube with A. The faucet at the lower end of the reservoir R is now opened sufficiently and the solvent passes into A from above, and as it descends takes up more and more oil, flows through the sieve-plate, and escapes through the tube at the bottom of A through the three-way cock, the overflow tube, and the drain tube into the accumulator C. The opening of a faucet now admits steam to the heating coil, when the solvent evaporates, leaving the oil or fat behind. It is condensed in B, again returns to R, whence it passes once more through the faucet into the extractor A. The vessel C and the tubes leading to A and C are surrounded with felt to prevent loss of heat. A sample taken from the small cock at the foot of A (it has a small plate in the interior of the tube) will show when the extraction in A may be looked upon as finished. The solvent is distilled off or recovered from the residue in A in the following manner. First the faucet in R is closed. The three-way cock A is set to establish direct communication between A and C, thus cutting off the overflow tube. Hence all the solvent in A flows into C for distillation, while the oil is left behind. Steam being admitted to the residue, the solvent rises as vapor through the upper tube from A to B and collects in a liquid state in R. To drive off the last traces of the solvent from the fat or oil obtained, steam is blown into C by opening the valve. Besides the solvent, watery vapor enters B and forms a layer of water in R under the solvent. By taking a sample from the test-cock of the reservoir C which has an internal small plate, the termination of the process is ascertained. The gauge tube at the reservoir shows the level of the solvent and water. The water is drawn off by opening the faucet at the lower end of the reservoir. A is emptied through the manhole and by draining the oil from C through the discharge cock. The tube R is closed by a light valve so as to prevent evaporation of the solvent. All the apparatuses work without pressure so that there is no danger from overstrain.

Fig. 27.

The solutions of the essential oils in bisulphide of carbon are distilled off in the steam still illustrated in Fig. 27; the steam enters at h, the water of condensation escapes at d, the liquid to be distilled enters at e from a container at a higher level. The boiling is kept uniform by the stirring arrangement hg. After the bisulphide of carbon is distilled off, air is passed through the oil by the curved tube a which has fine perforations, so as to evaporate the last traces of the solvent.

Fig. 28.

In Vohl’s apparatus (Fig. 28), arranged for petroleum ether, the extraction is effected with the boiling fluid; hence this apparatus is better adapted for the cheaper oils than for the finest oils from flowers. The apparatus consists of two extractors A A, the accumulator B, and the condenser C. Petroleum ether is allowed to flow over the substances to be extracted, by opening the faucets mm, vh, closing ogwE, and opening o, the course being through ux to B. When B is two-thirds full, the flow of petroleum ether is cut off, steam is admitted through y and the contents of B are brought to the boiling-point. The vapors pass through g and are condensed in f until the contents of A reach the boiling-point of the solvent, when the vapors pass through i into C, and after closing m´ the liquid passes through ml into the inner cylinder of the extraction apparatus and returns through uxx.