Large Stoppers in Small Bottles My note1 on removal of mhber stoppers inadvertently pushed into flasks or battles has generated a number of alternative suggesti~ns.~ Recently, however, I discovered an important side benefit in my method. A no. 5 stopper, left too long in an excess of toluene,swelled to enormous size. I drained off the excess solvent then closed the flask with acorkstapper (toprevent drying), making an intriguing display. Students were encouraged to guess how the display was made. After a variety of unproductive hypotheses, notation of the solvent odor and the number "5" on the stopper led to the correct hypothesis of solvent swelling. (A lack of swelling in polychloroprene ruhher stoppers may he demonstrated for contrast, and the use of polychloroprene for gasoline hoses, etc., may be noted.)
' Hill, J. W., J. CHEM. EDUC., 54,384 (1977). Pray, A. R., J. CHEM. EDUC., 55.31 (1978). Naslanie, J., Chemist-Analyst, 67, [2] 8 (1978). Madero, H. C., ChemrstAnalyst, 67, [2], 8 (1978). University of Wisconsin River Falls. 54022
J o h n W. Hill
Volume 56, Number 5, May 1979 1 333
