DECEMBER, 1948
657
AN IMPROVED SEMIMICRO DISTILLING TUBE GERALD R. LAPPlN ~~tioo College, h yellow
springs,ohio
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SEMIMICRO distilling tube as described by Cheronis,' while quite convenient for the distillation of small amounts of material, suffers from three drawbacks. High boiling liquids are almost invariably contaminated by contact with the rubber tubing which must be used to connect the side arm of the distilling tube to the delivery tube. Atmospheric moisture often condenses on the finger condenser used with this setup, giving a wet distillate. Receivers cannot be changed rapidly enough by an inexperienced student to allow a distillation to proceed in the desired steady manner when collecting fractions. Figure 1illustrates a modification of this apparatus which eliminates the rubber connection and the finger condenser and which permits very rapid change of receivers. It has been found to give considerably less trouble in the hands of beginning
' C m n o ~ r sN. , D., "Semimicro and Macro Organic Chemistry," Thomas Y. Crowell Co., New York, 1942, p. 63.
students. For liquids boiling below 100°C. it is necessary to wrap the side arm with damp toweling. Very volatile liquids, such as ether, require cooling of the receiver in a beaker of water. The semimicro fractionating column of CheronisZ may be similarly modified to eli.minate the same difficulties.
