AN INEXPENSIVE BURET SUPPORT H. ARMIN PAGEL, UNIVERSITY 01. NEBRASKA, LINCOLN,NEBRASKA Various types of buret supports and devices for convenient filling can be found in the literature. We have used the design shown in Figure 1 for the past two years in several of our research laboratories and find i t unusually satisfactory. This type of support includes the following desirable features. (1) The materials required are very inexpensive and are usually available in any laboratory. ( 2 ) No special mechanical skill is required for its construction. (3) It can be fitted equally well to any size of reagent bottle. (4) Reagent bottles thus equipped can be conveniently transported without dismantling, and the solution can be thoroughly agitated without danger of breaking the apparatus. (5) The buret is held rigidly a t both ends and the scale is nowhere obstructed. (6) The flexible rubber buret connection totally eliminates breakage of the glass tubing due to misalignment or slight distortion. (7) The wood upright protects both the flask and the reagent bottle from accidental breakage d u e to striking the flask against the bottle when titrating into a flask. (8) The buret is easily and quickly filled by suction and, unlike the gravity-filled type, ~. there is no danger of any reagent entering the buret during titration. In Figure 1, A represents a regular single buret clamp with the rod clamp removed. B is a wood slat 3/4 inch thick by 1 and '/z inch wide and of suitable length. The wood slat is firmly attached to the bottle with wires C. Rubber cushions D prevent the slat from slipping sidewise. The buret is filled by attaching a rubber tube to the glass tube E and suck160
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ing. Tube E is secured with adhesive tape a t F. A capillary tube G prevents undue evaporation, and serves for the air inlet. Figure 2 shows the details of the flexible rubber buret coupling. This permits the use of a considerably larger two-hole stopper than could be ~ r o ~ e r linserted v directly into the buret opening and provides splendid flexibility. Figure 3 shows the type of buret coupling used for alkaline solutions, where the buret must be removed and cleaned promptly after use to prevent etching. H is a glass tube about 1 inch inside diameter (the neck of a FIGURE2 broken distilling flask is ideal). I is a twohole stopper which remains permanently fixed. A rubber stopper J is bored so it will fit the buret top very snugly. This stopper remains fixed on the buret. In order to remove the buret from the coupling it is merely necessary to loosen the lower clamp (Figure I), and with a gentle twisting motion loosen the buret above. In order to prevent stopper J from sticking in tube H, the contact surface of the stopper is rubbed with graphite containing a little vaseline. Since the solution does not come into contact with the stopper, there is no danger of contamination. This type of coupling does not possess the flexibility of that shown in Figure 2, but Frcmt~3 due to the fact that stopper I is rigidly fixed, the small glass tubes are not strained while removing or replacing the buret.
Acetaldehyde Tried Out in Fruit Preservation. Acetaldehyde vapor may prove of future use in the preservation of fruit because it kills the spores of molds without injuring the fruit itself. This conclusion has been reached by two investigators who have worked on different sides of the question. R. G. Tompkins, of the Low Temperature Station, Cambridge. has shown that acetaldehyde vapor rapidly kills the spares of the molds and fungi which are likely to cause fruit spoilage. I n the same laboratory, S. A. Trout has recently found that healthy fruits ran absorb a certain amount of acetaldehyde vapor without any harmful effects. The acetaldehyde is used up by the tissues of the fruit and soon disappears, leaving no trace of flavor. The possibility of applying this work to the fruit industry is under investigation.-Science Service
