Perfumes and their preparation

by George William Askinson

The vegetable substances to be distilled can be put immediately into the still and covered with water; but in this case it is advisable to use a stirrer which must be kept moving until the water boils, otherwise the material might burn at the bottom. But this accident can also be prevented by applying a perforated false bottom to the still above the flues, or by inclosing the material in a wire-sieve basket C.

In place of the basket C the apparatus can also be provided with an additional vessel containing the material to be distilled. In the still A (Fig. 10) the water is brought to boiling, the steam rises through the second still B in which the material is spread on a perforated bottom. The steam laden with the vapors of the essential oil passes through the tube R into the condenser.

Fig. 11.

It is very advantageous, and in large establishments altogether indispensable, to use steam in the distillation of essential oils. Fig. 11 represents the arrangement of such an apparatus. The still B (which in this case may be made of stout tinned iron) stands free and is provided with a wooden jacket M for the purpose of retaining the heat. Immediately above the curved bottom is a perforated plate on which the material rests. The tube D which enters the bottom of the still is connected with the boiler which furnishes steam at moderate tension. H is the faucet for the admission of steam; H. is the faucet by which the water escapes from the still at the end of the operation. After the still is filled with the material, the faucet H is opened gradually and a continuous stream of steam is allowed to pass through the still until the operation is finished.

When working with an open fire, as soon as vapors appear at the lower end of the worm (Fig. 9), cold water is admitted through the tube ne; as the cold water abstracts heat from the vapors and condenses them, it becomes warm, rises to the surface, and escapes through b, so that the worm is continually surrounded with cold water. If for any reason the saving of cold water is an object, its flow may be so regulated that the vapors are just condensed, the warm distillate being allowed to cool in the air. When working with steam, the cold water must be admitted the moment the steam-cock is opened, and the flow of cold water should be ample during the distillation, which in this case is much shorter.

The large apparatuses here described are generally used, especially for the extraction from vegetable substances of odors present in considerable quantity, for instance, mace, nutmeg, cloves, cinnamon, etc., or from bulky material as the various flowers. For very expensive odors, smaller apparatuses are often employed, the construction of which resembles that of the ones described. For this purpose small glass apparatuses are very suitable; they are illustrated in Fig. 12.

The still, a retort A, consists of a spherical vessel with a bottle neck t which is either closed with a cork or carries a thermometer or glass tube, and with a lateral tube, the neck of the retort, connected with the adapter r. The latter passes into the condenser C. At the lower end of R is the bent adapter v under which is placed the receptacle for the distillate. The tube C is closed with corks, at its lower end is the ascending tube h, and at its upper end the descending tube g. During the distillation cold water flows in through h which cools the tube r and escapes at g. The tube C, as will be readily understood, acts like the condenser in the larger apparatuses above described. In order to prevent the breaking of the retort, it is not heated over a flame, but is set in a tin vessel B filled with water. The comminuted vegetable material is inserted with water through the up-turned neck of the retort into the latter; the vessel B is filled with water which is raised to the boiling-point.

Fig. 12.