Identifier: practicalmethods00gatt Title: Practical methods of organic chemistry Year: 1901 (1900s) Authors: Gattemann, Ludwig. [from old catalog] Subjects: Publisher: [n.p.] Contributing Library: The Library of Congress Digitizing Sponsor: The Library of Congress

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Text Appearing Before Image: 22 GENERAL PART so that the vapours do not come in contact with the cork. Butgenerally a cork is not used; the outlet tube being inserted suffi-ciently far into the condenser. Heating. — Low boiling substances (those boiling up to about8o°) are not generally heated over the free flame, but on the water-bath gently or to full boiling. Frequently it is more convenientto immerse the bulb of the fractionating flask as far as the levelof the liquid which it contains in a dish or beaker filled withwater, which is heated gently or strongly as the case requires.Low boiling substances may also be heated by immersing the bulb

Text Appearing After Image: Fig. 18. of the flask from time to time in a vessel filled with warm water.If a substance is not distilled over a free flame, in order to prevent bumping a few pieces of platinum wire or foil, or bits of glass,are thrown into the liquid (see below). When a substance to bedistilled is heated on the water-bath, it may easily happen thatthe vapour inside the flask may be overheated by the steam escap-ing between the rings. For this reason, in the determination ofexact boiling-points it is better to use a small free flame. Theso-called microburner is well adapted to this purpose. High boil- DISTILLATION 23 ing substances are always heated over the free flame. In this casethe flask may be protected by heating it on a wire gauze; still byworking carefully the gauze need not be used. In heating, theflame is not placed under the flask at once, since the latter is likelyto break easily on sudden heating; it is better to pass the flameback and forth slowly and uniformly over the bottom of the f

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