A NEW DISTILLATION COLUMN* E. H. PARKE Oberlin College, Oberlin, Ohio
FOR some years there has been the criticism of the distillation columns of the two-bulb type shown in the catalogs in that they were unnecessarily large and cumbersome for convenience in the college laboratory. About fifteen years ago the writer designed a distillation colnmn which has been used in this laboratory ever since. This column was 21 mm. o.d., and 180 mm. overall. The upper bulb was 35 mm. outside diameter and the lower one 25 mm. 0.d. The two were separated by a constriction 25 mm. long and 9 mm. 0.d. The side tube, 150 mm. long and 6 mm. 0.d. was sealedon to the colnmn 35 mm. from its top. This design has now been changed to the following. The new column is 220 mm. overall and 22 mm. 0.d. Both bulbs are of the same diameter, i. e., 35 mm. 0.d. The upper bulb is 80 mm. from the top of the column and separated from the lower one by a constriction 20 mm. long and 10 mm. 0.d. The side tube is sealed on to the colnmn 40 mm. from its top, a t a 70' angle to the lower column, and is 150 mm. long and 6 mm. 0.d. The tip of the column is of the same diameter as the -
* See Editor's Outlook.
constriction between the bulbs and is 50 mm. long with the end ground to a 60" angle. This column will be found to be much more efficient than the larger ones in distilling small quantities of liquids. While these columns were formerly of ordinary glass, it is preferable to make them of Pvrex in order -to minimize breakage, although the initial cost is perhaps twice that of ordinary glass. The walls of the bulbs should be as thick as the stock of the column will permit so that when glass beads or short pieces of glass tubing are used in the bulb, to facilitate fractionating, breakage is less likely to occur when they are dropped in.
