Modification of a Constant Flow Buret A recent article in this Journal' described a constant flow buret, which we found to be very reliable. A common reagent used in this system is a strong base such as NaOH. The normality of a standardized NaOH solution is subject to change as a result of reaction with COz in the air. The exposure of the titrant to the air in the funnel of the original apparatus limits the use of the apparatus to very short periods. The design shown replaces the open funnel with a polypropylene beaker fitted with a large rubber stopper. The stopper was bored to accept the two tubes as shown in the original apparatus. To allow for air entry an additional hole was bored and fitted with an Ascarite drying tube. This provides a system that reduces exposure to COz. Another hole was bored in the bottom of the beaker and fitted with a stopper and glass tube packed with glass wool. Our tests indicate a reliability of *0.4%, measured both in relation to mass delivered per unit time and in number of drops of titrant per unit time. We used a flow rate of approximately 4 ml/min. With this controlled atmosphere around the titrant the apparatus can be assembled, calibrated and left in the laboratory for several days with no serious effect an the concentration of the titrant. Walton, H. F., J. CHEM. EDUC., 50,195(1973)
Ames Senior High S e h w l Ames, Iowa 60010
Floyd Sturtevant Kenneth Hartman
Volume 52, Number 6, June 1975 / 393
