Hemi-Nguyen, T. V.; Brennen, C.; Sabersky, R. H.Rates of absorption of sulfur dioxide in calcium hydroxide solutions were measured by use of a laminar jet apparatus and contact times of between 10 and 25 ms. The hydroxyl ion concentration in the calcium hydroxide solutions was varied between 0.025 and 0.041 g-ion/L, and the sulfur dioxide concentration in the mixture of nitrogen and sulfur dioxide was varied between 0.96 and 2.86%. Under these conditions, the reaction is instantaneous and the results agreed well with the penetration theory.Greek Symbols j3 = a parameter determined from eq 7 or a measure of reaction 0 = time of contact, s Subscript 0 = initial Superscript * = at the interface Registry No. SOz, 7446-09-5; Ca(OH)z, 1305-62-0. Literature Cited B i b , I.; Bengetsson, S.; Farnkvist, K. Chem. Eng. Scl. 1972, 27, 1853. Boelter. L. M. K. Trans. Am. Inst. Chem. Eng. 1943, 39, 557. Cullen, E. J.; Davldson, J. F. Trans. Faraday Soc. 1962, 53, 113. Danckwerts. P. V. "Gas-Lbuid Reactbns"; Mcoraw-HiII: New York, 1970; p plane movement, cm/s1I2 81. p 481. Hobbler, T. "Mass Transfer and Absorbers"; Pergamon Press: Oxford, 1968; CORRESPONDENCE Matsuyama, Y. Mem. Fac. Eng. Kyoto Unlv. 1953, 15, 142. NiJsing, R. A. T. 0.; Hendriksz, R. H.; Kramers, H. Chem. Eng. Sci. 1959, Onda, K.; Kobayashl, T.; Fugine, M.; Takehashi, M. Chem. Eng. Scl. 1971, Onda, K.; Sada, E.; Kobayashi, T.; Odaka, M. Kagaku Kogaku 1969, 33, 886. Rehm, T. R.; Moll, A. J.; Babb, A. L. AIChEJ. 1963, 9 , 780. Scriven, L. E.; Plgford, P. L. AIChEJ. 1959, 5 , 397. Sharma, M. M.; Danckwerts, P. V. Chem. Eng. Sci. 1963, 18, 729. Toor, H. L.; Raimondi, P. AIChE J. 1959, 5 , 86.