. Electronic apparatus for biological research . Figure Stages in the lateral fusion of two glass tubes end and when soft both tubes are blown so that they stick together. By repeated heating and blowing the tubes at this point can be fused together by varying amounts. The least degree of fusion is that when the tubes simply form a figure 8, while complete fusion gives a structure with oval cross-section containing two D shaped compartments back to back {Figure ). As the heating proceeds the glass tends to flow from the dividing wall to the exterior, and if excessive may lead to a v
. Electronic apparatus for biological research . Figure Stages in the lateral fusion of two glass tubes end and when soft both tubes are blown so that they stick together. By repeated heating and blowing the tubes at this point can be fused together by varying amounts. The least degree of fusion is that when the tubes simply form a figure 8, while complete fusion gives a structure with oval cross-section containing two D shaped compartments back to back {Figure ). As the heating proceeds the glass tends to flow from the dividing wall to the exterior, and if excessive may lead to a very thin and fragile partition. When the required degree of fusion is achieved the glass is drawn down to a diameter of 1-2 mm, while it is gently blown by mouth. Hence- forth the tube can be treated as a single channel microcapillary and drawn down further manually or by machine. Often however, as a result of unequal stresses, the tube tends to flatten and occlude, and this can be prevented by applying a slight air pressure (4 in. water) during the draw. Another method of making a two-channel tube is to fuse a glass partition ( microscope slide) across the middle of a wide-bore tube. Electrical leakage—To prevent electrical leakage between the two channels at the stem an angled tube can be cemented into each channel by means of a low melting point wax such as Picene or dental wax. Alternatively small portions of the unfused parent tubes can be left and slightly separated^^. Leakage between the two compartments in the shank or near the tip may also cause difficulty. Leaks can be detected sometimes by comparing 561
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, bookleafnumber609
