A Quick-Disconnect Fitting for Gas Handling Applications Difficulties associated with the met,hod of sample introduction in t,he Victor-Meyer experiment, and with reprodueibly filling and weighing Dumas bulbs have hindered t,he development of a simple yet accurate method of determining gas molecular weights fnr physical chemistry classes. Over the past. four yews our classes have used a commercially available compression fitting ["Swagelok," Crawfard Fitting Co., 884 East 140th St., Cleveland, Ohio] to make simple, inexpensive connections between glass Dnmaq bulbs and both metal and glass gas handling manifolds. By using Teflon ferrules in one of the many available metal and p l a ~ t i cfitting eonfiguratiolls, greaseless yet vacuum tight seals are quickly made with only finger tightening of t,he cap nut which swages the ferrules against the bulh tobolatian. We use 250 ml bulbs having one stopcock with nominally 8-mm arms and we find that it is usually necessary to drill 5/16in. fittings slightly oversize to acecmodate the stopcock arm. Alternatively, one might reduce the arm to an inch fraction size so that the compression fitting may he used without alteration. (Alterations of the ferrules are unnecessary because they are rather pliant.) The ferndes may be reused repeatedly unless scratched or over-tightened. Even when gas-tight these joints may be pulled apart, however, so their use whore manifold pressures exceed atmospheric is not generallyadvisable. T. EHLERT
IMARQUETTE UNIVERSITY MILWAUKEE. WISCONSIN 53233
196
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Journal of Chemical Education
