PREPARATIONS 83 by steam. If steam is not laid on in the fume-cupboard, it should be generated outside the cupboard in the usual steam-can (Fig. 15, p. 33) and then led into the cupboard through a length of soft metal "compo" tubing. The flask is supported on the usual concentric metal rings over an empty water-bath: a hole is punched in one of the outer rings, and then the compo tubing is led down throught this hole into the bath, and the extreme end of the tubing turned up so that the jet of steam strikes directly upwards on to the base of the flask. If the fume-cupboard has a vigorous draught induced by an electric motor, large quantities of the ether can thus be safely distilled, and an ordinary bottle can be used as a receiver, the end of the condenser being fitted into the neck of the bottle and held firmly in position by a plug of cotton-wool. If a large Buchner flask is used as a receiver, the rubber delivery tube (as shown in Fig. 54, p. 8o, and in Fig. 23(E), p. 45) is of course required.
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