LETTERS To the Editor: The comlnunication by S. Lowell [THIS JOURNAL, 42, 552 (1966)l-concerning the reduction of the general equation for the kinetics of a bin~olecularreaction to the special case in which the reactant concentrations are equal-recalled to my mind that the use of 1'Hospital's rule in this connection had been indicated by the remarkable chemist J. W. Mellor, in hiq "Higher hlathematics for Students of Chemistry and Physics," 4th edition, 1913,p. 30'7 (Dover Publications, New York). It may be of interest to mention that an alternative treatment is given in my L'Te~tbool< of Physical Chemistry," D. Van Yostrand Co., Inc., New York, 1940, p. 1035; and in the 1946 edition, p. 1055. I do not claim originality for the latter, but a t this date I do not recall where it came from. SAMUEL GLASSTONE LOS. ~ L A ~ ~ SCIENTIFIC OS L~ORATORY Los ALAMOS, NEWMEXICO
46
1 Journal
of Chemical Education
To the Editor: Regarding B. Miller's note in THIS JOURNAL, 42, 617 (1965) and his concern with multiple prolonged underwater magnetic stirrers in a constant temperature system, I would like to point out a possible alternative. The G. F. Smith Chemical Co. (867 McKinley Ave., Columbus 23, Ohio) markets a small plastic magnetic stirrer for $6.50 (12 for $60) which may be powered by compressed air, vacuum, or running water; i t is purported to work equally well under water or on the bench. The stirrers may be connected in series via hose connections. While we have found water power to be most effective for small variations in speed, whichever power source is most constant in one's laboratory would have the greatest utility for prolonged use. Although water affords simultaneous cooling of the simple rotating magnet, I am not aware that the other power sources generate any appreciable heat. DANIELKRUH HERC~ POWDER E ~ COMPANY GLENSFALLS, NEW YORE
