METHODS AND MANIPULATION 9 a water-bath for additional safety. Whether a liquid can thus be distilled from a boiling water-bath will depend chiefly on its boiling-point and also on its latent heat, but as a general rule most liquids of boiling-point below 80° may be distilled readily in this way: for liquids of higher boiling-point a sand-bath or direct heating on a gauze is necessary. Thus ethanol (boiling-point 78°) can be distilled from a water-bath: benzene (boiling-point 81°) will boil gently when heated on a water-bath, but not sufficiently vigorously to distil over at an appreciable rate. __ The water-condenser B shown in Fig. 2 represents the simplest and cheapest kind, which because of its limited efficiency should be at least 2 feet long. Fig. 3(A) shows a bulb condenser, which, although also cheap, is much more efficient. In Fig. 3(B) is shown the usual double-surface condenser, which, although more costly than the two former condensers, is far more efficient, and need be only one-third to
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