Some manufacturers who prepare their odors by extraction, may find it advantageous to make also the bisulphide of carbon necessary for it, and this is best done in Gérard’s apparatus (Fig. 1). It consists of a cast-iron cylinder _a_, two metres high and one metre in diameter. This cylinder is heated on the outer surface in an oven, and two tubes, _c_ and _d_, are attached to it. Tube _d_ is connected by _e_ with the hemispherical vessel _b_ which is connected by the tube _i_ with the condenser _mlk_. The condenser is formed of three cylinders made of sheet zinc which are surrounded with cold water. The condensed liquid escapes into the vessel _p_, while the gaseous products pass through _n_ into the chimney. The cylinder _a_ is filled with about 1,500 pounds of charcoal or coke in small pieces, after which it is closed and all tubes are carefully luted with clay; _a_ is then heated to a strong red heat and at intervals of three minutes 3 pounds of sulphur are thrown in through _c_. In twenty-four hours, by the use of 478 pounds of sulphur, 568 pounds of crude bisulphide of carbon are obtained; a portion of the sulphur distils over uncombined into the vessel _b_. [Illustration: FIG. 1.] The crude bisulphide of carbon contains about twelve per cent of sulphur and other combinations in solution and is redistilled at exactly 48° C. (118.4° F.) in a steam-heated apparatus with a long exit tube cooled with ice below and water above. In order to obtain the bisulphide of carbon absolutely pure, which is essential to render it suitable for extraction, it is again distilled at the same temperature, with the addition of two per cent of palm oil. As the vapors of bisulphide of carbon are injurious to the organism, the vessels containing it must always be kept well closed. B. Chemical Products used for the Preparation of Perfumes. Among all the substances belonging under this head, there is one which plays a prominent part in the manufacture of most perfumes. In handkerchief perfumes it is one of the most important substances, as it forms not only the greatest bulk, but the perfection of the perfume depends upon its quality. This substance is— ALCOHOL, also called spirit of wine; French, esprit de vin; the well-known combustible liquid formed by the alcoholic fermentation of sugar, which is made on a large scale in extensive distilleries. Alcohol is a thin, mobile liquid with an aromatic odor. The usual “strong” alcohol of the market contains about ninety-four per cent of absolute alcohol by volume. This has a specific gravity of 0·820. Its boiling-point is 78·2° C. (172·40 F.), and it congeals at a very low temperature, below -100° C. Alcohol possesses great solvent power for resins, balsams, and essential oils.