Imágenes de páginas

JOURN. PRAKT. CH. = Journal für praktische Chemie, vols. i.

cviii. (1834-1869). 3 vols. annually. Neue Folge since 1870.

2 vols. annually. MONATSH.

= Monatshefte für Chemie, vol. i. (1880).

i vol. annually. Phil. Mag.

Philosophical Magazine, vol. i. (1798). PHIL. TRANS. Philosophical Transactions of the Rnyal

Society, vol. i. (1665). 1 vol. annually. PROC. Roy. Soc. Proceedings of the Royal Society, vol. i.

(1847). I to 2 vols. annually. Pogg. ANN.

Poggendorff's Annalen der Physik und

Chemie, 160 vols. (1824-1877). Neue
Folge, edited by J. Wiedemann, vols.

i.-ii. (1877). 3 vols. annually. ZEITSCHR. F. Ci. Zeitschrift für Chełnie (Beilstein, Fittig,

and Hübner), vols. i.-vii. (1865-1871). PRACTICAL ORGANIC CHEMISTRY.





Commercial absolute alcohol (ethyl alcohol), obtained by rectifying crude spirits of wine over quicklime, is seldom free from water. The alcohol may be further dehydrated by allowing it to stand for twenty-four hours in a flask half filled with freshlyburnt and coarsely powdered quicklime, and then distilling off on the water-bath. The apparatus for this purpose is represented in Fig. 1. The alcohol if pure boils constantly at 78°—79o. The temperature is indicated by a thermometer inserted through the cork in one limb of a T-piece a, the other end of which is fitted vertically into the flask. The side limb is bent through a small angle and passes into the inner tube of the condenser. The bulb of the thermometer is adjusted below this side limb, so that it is heated by the ascending vapours of the boiling liquid.

BOILING-POINT DETERMINATION.-A correct determination of the boiling-point of a liquid is made with a standard thermometer, correction being made for barometric pressure, and, if necessary, for the thread of mercury which projects above the vessel. For the latter the formula given in a foot-note on p. 25 may be used. It is, however, preferable to increase the length of the distilling tube, so that the mercury column is entirely immersed in the vapour.

Methylated spirit is a mixture of 9 parts spirit of wine and i part purified wood-spirit, and contains

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in addition to ethyl and methyl alcohols, water, fusel. oil, acetaldehyde, and acetone. It may be freed from aldehyde and acetone by boiling with 3-4 per cent, solid caustic potash on the water-bath with reflux condenser for an hour (Fig. 2), and then distilling off on the water-bath. It is freed from water

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