Defuzzing Tennis Balls-For a Shattering Game ol Hard Ball I have difficulty finding hollow rubber balls suitable for freezing with liquid nitrogen to shatter or crush inmy "chemical magic" show.' Used tennis balls are now easy to obtain; however, they do not shatter well without "defuzzing." I remove the fuzz (or nap) by treating the fuzz on the ball with concentrated hydroehlarie acid to which a little cationic detergent, e.g., benzalkonium chloride, is added. I place the ball in a freezer box, saturate the fuzz with the acid solution, and seal the box. After the ball stands for about two days a t r w m temperature, the nap can be removed quite easily. I drop the ball into a large amount of tap water, remembering that I am handling strong acid, rinse it well with tap water, then neutralize excess acid by soaking it in sodium bicarbonate solution. When the acid-treated ball is first placed in water, the dissolved nap forms a colored fibrous precipitate, demonstrating solution of the oolvmer in atrone acid. After neutralization o f t h e k d . I scrape off the polymer adhering to the rubber ball with a dull knife or spatula, cut off the raised part of the ball with sharp scissorr, rinse the ball well, then dry. In the show, the t d l5.i dropped into liquid nitrogen, allowed tcr freeze hard, t h m shattered by "bouncing" it on asuimble surface. With appropriate care one can shatter the frozen ball on the table with one's band. ~
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Cady, H. P., J. CHEM.EDUC.,8,1034 (1931). Leon S. Ciereszko Tiw University of Oklahoma Norman. OK 73019
Volume 61
Number 10 October 1984
907
