A Combination Steam and Cold Plate The apparatus, shown as a side view (114 scale) in the sketch, was constructed to serve as a variable-temperature plate far use during magnetically stirred evaporation of solvents, dissolution of solids, and cooling solutions to induce nystallization. It has the major advantage that steam or water does not escape around the bottom of a vessel during use and that lower solution temperatures are readily achieved. The construction is of brass, and soft solder was used to seal the seams. The upper and lower plates were constructed from 8-in. diameter (U8-in. wall thickness) brass plates. These plates were connected hy a 5-in. diameter (U8-in. wall) x 718-in. length of brass tubing. The inlet and outlet ports may be of 114-in. brass tubing fitted into the vertical wall with a soft-solder seal at opposite sides (1803, as shown, or the walls may be drilled and tapped (118-in. pipe thread) to accept brass hose connectors which have a serrated tip to fit 114-in. i.d. tubing. This hose-connection fitting may be purchased a s part No. 4-HC-1-2 from Cajon Co. (9760 Shepard Rd., Macedonia, OH 44056) or as part No. 308 from Parker Quick Coupling Division (8145 Lewis Rd., Minneapolis, MN 55427). Steam or hot water is used for heating and cold water or recirculated glycol provides emling. To compare the effectiveness of the steam plate with that of a conventional steam bath, l-L of water, contained in a 4-L beaker, was heated from 23 C ' for l-h. Using a steam bath, the temperatures, recorded at 10-min intervals, were: 53,67,71, 72, 73, and 73% Using the steam plate, with magnetic stirring, the temperature rose a s fallows: 33,40,45,48,50,51oC.Efficient magnetic stirrers' and s t i ~ h a r sof~ local , ~ construction, used with this apparatus, have been described. 'Hall, H.; Elssnbraun, E. J. J Chem Educ 1977 54,229. 'cawan, K. D.; Bymaster, D. L.; Hall. H.; Eisenbraun, E. J Chem Ind 1986, 105. 3~enzler,R. L.; Lucas. M.:Eisenbraun, E. J. J Chem Educ 1991. 68.85.
E. J. Eisenbraun and J. M. Lucas Oklahoma State University Stillwater,OK 74078
416
Journal of Chemical Education
