On cooling, the distillate separates into two layers, one being a solution of the volatile oil in water, the other the pure oil. A tall cylinder or flask is used (Fig. 385), which, near the bottom, has a glass or other tube inserted, and curved upwards to a short distance below the top. The heavy water separating at the bottom will commence to discharge through the lateral tube b as soon as the vessel is nearly filled with the distillate, upon which will float a layer of volatile oil; this layer may be withdrawn by means of a small syphon, or, better still, through a lateral tube e inserted near the top of the vessel. If the volatile oil, however, is heavier than water, the conditions will be reversed, and the oil will flow through a and run off at b. The last portions of volatile oil are removed from the water by means of a separating-funnel (Figs. 396, 398), the separation being effected with a perforated glass stopper inserted in the neck, or by inclining the vessel (Fig. 397) through the tube a. For very small quantities a bulb-pipette or syringe-pipette will be found useful, the tube of which is drawn out to a fine point. By a suitable arrangement the separated odorous water may be returned to the still, while the distillation is progressing.

Fig. 395.   Separating Cylinder

Fig. 395. - Separating Cylinder.

Fig. 396.   Separating Bottle

Fig. 396. - Separating Bottle.

Fig. 397.   Separating Tube

Fig. 397. - Separating Tube.

Fig. 398.   Separating Funnel

Fig. 398. - Separating Funnel.

"If violatile oils are present only m minute quantities, frequent cohoba-tion is required, but even then too much is often lost by being retained in the water, as in the case of violets, tuberoses, etc. To obtain these delicate perfumes, Mil-lonand Commaille (1868) employed purified bisulphide of carbon, with which the material is exhausted, and on the spontaneous evaporation of which all the odoriferous compounds are left behind.

Fig. 399.   Frames with inodorous Fat for extracting Flowers

Fig. 399. - Frames with inodorous Fat for extracting Flowers.

"The process of enfleurage is likewise adapted for obtaining delicate perfumes. A number of trays or frames are covered with a layer.of purified tallow or other inodorous fat, and then with flowers, the latter if necessary being replaced by fresh flowers in a few days; when the fat is sufficiently charged with the perfume it constitutes the pommades used by perfumers. Liquid fats may be used in a similar manner for extracting such perfumes, the liquid portion of oil of ben being employed, because it resists rancidity for a long time; the huiles antiques are obtained in this manner. By digesting the solid or liquid fat with pure alcohol, the odorous principles are taken up by the latter, the spirit then constituting the extracts of perfumers; the small portion of fat entering solution separates on exposure to a low temperature. Extraction. - "L. Wolff (1877) proposed a process for preparing volatile oils, whereby distillation may either be entirely avoided or materially shortened. Petroleum benzin dissolves from plants chiefly; the volatile and fixed oils may then be separated either by distillation with water or by agitation with alcohol, removing the fat and wax, and separating the volatile oil from the alcohol by mixing with water.

Fig. 400.   Sectional View of Frames at Fig. 399

Fig. 400. - Sectional View of Frames at Fig. 399.

Fig. 401.   Extraction of Volatile Oils with Benzine, etc

Fig. 401. - Extraction of Volatile Oils with Benzine, etc.

Fig. 402   Distilling Apparatus

Fig. 402 - Distilling Apparatus.

D, M, M, is the jacketted kettle; R, the steam pipe with extension r leading into the interior of the kettle forming a perforated spout. Pipe R is also connected with M, M. This arrangement permits distillation by open or jacketted steam. C, is a cylinder connected with pipe A that leads the vapors to the condenser K. From these they run in the florentine flask F, and can either be re-ceived in bottles or directly returned to the kettle by means of the adjusted funnel.

Fig. 403.   Bulb Pipette

Fig. 403. - Bulb Pipette.

"Rectification is not infrequently desirable, since resinous compounds and coloring matter may thereby be removed and the color improved; it is best accomplished by mixing the volatile oil with half of its own weight of an inodorous liquid fat, and distilling the mixture from a solution of table salt, as stated above". - N. D.

The extracts, essences and tinct-ures prepared for the manufacture of carbonated beverages by digestion or maceration, are not infrequently rectified by distillation, and for this purpose the still represented by the annexed engraving, and manufactured by Lippincott, in Philadelphia, or that represented by Fig. 402, both jacketted, are very suitable vessels. Stills with a coil inside are also suitable, but none that are direct over a fire. Any essences, and especially fruit essences, that should be rectified by distillation, or in fact any liquid that enters into a still, and has acrid principles, should be put only in a well enameled or silver-lined kettle or still, steam-jacketted, as copper would be most injurious to the liquid, and iron greatly deteriorate it.

The still represented by Fig. 404 is made either for the use of steam, where such is available, or to generate its own steam on an ordinary furnace. It has safety valve, gauge cocks and water supply attachment.

On the small scale distillation is performed in the simplest way by means of the common glass retort, as illustrated later on in Chapter XXXII (Fruit-Syrups, And How To Make Them)., Extracts, Essences, etc' The retort may be either simple or tubulated, and sometimes the receiver has an arrangement to allow the escape of gas or expanded air. The great advantages of the glass retort are that it admits of constant observation of the materials within, that it is acted upon or injured by but few substances, and may be cleaned generally with facility. Its great disadvantage is its brittleness, met with in common glass retorts; however, only a retort of the best glass should be employed. 32

Fig. 404.   Laboratory Still

Fig. 404. - Laboratory Still.

When the common glass retort and receiver are used for the distillation of liquids, care should be taken not to apply the luting until the atmospheric air is expelled, except the receiver has a tubulure for its escape. The operator should aim at keeping the body of the retort hot, and the neck of the receiver cool. The latter will be accomplished by keeping the neck and receiver wrapped in wet cloths, on which a stream of cold water is kept running. Retorts are generally heated in a water or sand bath, placed over the naked fire in the way illustrated. Where it is to be subjected to a heat sufficient to soften the glass, the bulb may be previously coated with a mixture of clay and sand, and dried.