322 PRACTICAL ORGANIC CHEMISTRY end of the tube into water should always be performed imme-diately after heating: if the tube is allowed to cool somewhat beforehand, the reaction may then be far more violent. The sodium fusion and extraction, if performed strictly in accord-ance with the above directions, should be safe operations. In crowded laboratories, however, additional safety may be obtained by employing the following modification. Suspend the hard-glass test-tube by the rim through a hole in a piece of stout copper sheet (Fig. 69). Place 1-2 pellets of sodium in the tube, and heat gently until the sodium melts. Then drop the organic compound, in small quantities at a time, down * the tube, allowing the reaction to subside after each addition before the next is made. (If the compound is liquid, allow two or three small drops to fall at intervals from a fine dropping-tube directly on to the molten sodium.) Then heat the complete _ mixture as before until no further reaction occurs. FIG. 69.
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