Notwithstanding the volatility of bisulphide of carbon, the oil retains a portion of it so tenaciously that a complete separation cannot be accomplished by the introduction of steam into the jacket _B_. Hence, in order to vaporize the last traces of the solvent, air is introduced into the oil through the pipe _K_, the lower end of which is perforated. After completed distillation the oil is discharged through _L_. _Maceration or infusion._--This process is employed for flowers with an inconsiderable content of volatile oil or whose odoriferous substance would suffer decomposition or alteration by distillation. The process is founded on the affinity of odoriferous substances for fatty bodies which, when impregnated with them, are called _pomades_. These are afterwards made to yield the aroma to strong alcohol, so that finally there is obtained a solution of the volatile oil in alcohol from which the pure oil is obtained by distilling off the alcohol. The fat used, olive oil, lard, etc., should be entirely neutral, _i. e._, free from every trace of acid. The fats are purified by treating them several times in the heat with weak soda-lye and then washing carefully with water until the last traces of the lye are removed, and the fat shows no alkaline or acid reaction. With the use of olive oil the so-called "_Huiles antiques_" are obtained, which are merely solutions of volatile oils in the fixed oil. By the use of lard, etc., the genuine _pomades_ are obtained, which are directly used as expensive articles of perfumery, but in the factories serve as a starting point for the preparation of volatile oils. The old process of maceration, which is still in use in some parts of France, is as follows: A certain quantity of fat is placed in an enameled iron or porcelain pan provided with a water or steam bath. When the fat is melted, the freshly gathered flowers from which the aroma is to be extracted are thrown in and left to digest for from twelve to twenty-four hours, the fat being kept fluid and stirred frequently. When the flowers are completely exhausted, the fat is strained from them into fresh pots, in which it is again macerated with fresh flowers as before. This operation is repeated ten to fifteen times until the pomade has acquired the desired strength.