Bulbs at the end of a tube

Blowing Bulbs at the End of a Tube Blowing bulbs on the end of tubing may be found difficult because there is no portion of tubing to help to keep the bulb central whilst it is being blown. A round end is first made on the tube, which is... 

The first and simplest is the blowing of bulbs at the end of a tube. When the required bulb is small and with comparatively thin walls, the spindle on one end is melted off and the end rounded as for a test-tube. A length of tube at this end not exceeding twice the bore of the tube is softened down in a fairly large flame, a slow and uniform rotation being maintained to ensure equal heating and softening all round. When the tube... 

An interesting and simple work of this class is the vacuum bowl illustrated in Fig. 25 (7). For this a bulb is blown at the end of a tube, and the outer hemisphere of it slowly softened down in a large brush flame to shape (6) and then gently sucked in, when the shape (7) results without further ceremony. 

Quantities of 0.05—0.5 ml are frequently distilled in a small bulb blown at the end of a tube. The method of filling is to heat the bulb (similar to Fig. 126) gently and allow it to suck up the liquid during cooling, or to employ a capillary pipette. The use of bulb tube.s has been extensively treated by Bertele and Humbel [3b]. Even... 

To measure the pH of a solution electrochemically, we need an electrode that responds to changes in [H" (aq)]. We noted that the standard hydrogen electrode is difficult to use for this purpose, and so, for routine use, a simpler and safer electrode is needed. Such an electrode is theg/ass electrode, which consists of a very thin walled glass bulb (see Figure 19-13c) at the end of a tube that contains a silver-silver chloride electrode and a HCl solution of known composition (e.g., 1 M). When the bulb is placed in a solution of unknown pH, a potential develops because of the concentration difference across the membrane, analogous to a concentration cell. To measure this potential difference, a reference electrode is used, which can be either a saturated calomel electrode or a second silver-silver chloride electrode, as in the combination electrode shown in Figure 19-13(d). The overall cell can be represented as... 

A method for making larger thin windows has been described by J. T. Lloyd (1949). For windows in the end of a tube he advocates the blowing of a thin-walled bulb at that end and then drawing it into the tube to form the window by the following method the thin-walled bulb is blown at the end, the wall of the tube is then heated all round at a short distance from the end imtil the glass is fused, and then the... 

The basic principle of this method is to let a drop dangle loose at the end of a fine capillary tube. The drop takes on the shape of a light bulb (Figure 2.20). 

Experiment.—Determine the Absolute Density of Dry Air. The volume of the bulb and its weight when exhausted are first determined, as explained above. The diy bulb is then clamped in a bath of water kept at a constant temperature, say 25° (see Chap. IV.), so that the bulb is entirely immersed, but not the stopcock (Fig. 10), and a T-tube a is attached to it by means of pressure tubing. The side tube of a is connected with a Fleuss or mercury pump by means of pressure tubing on which there is a screwclip, I and to the end of a tube of calcium chloride is attached, also by means of pressure tubing furnished with a screw-clip, II. This clip is kept closed,... 

During this process some water will have condensed in the steam-trap D and also in the distillation bulb F. If at the end of the steaming-out process, the Bunsen burner is removed from the generator A, the pressure in A will be reduced owing to steam condensation, and the liquid in F will be sucked back into D provided that the benL-over tube is carefully adjusted, the bulb F may be almost completely emptied of liquid as desired. Finally the condensed water in the steam-trap D may be run out by op ing the tap Tj. 

If preferred, suitable ignition tubes may be prepared by the student from soft glass tubing it is important that the thickness of the glass at the closed end be tmiform, otherwise the tube is likely to crack when heated. The simplest procedure is to blow a small bulb of uniform wall thickness at the end of the tube. The small test-tubes are available from all laboratory supply dealers... 

An Ostwald viscometer is similar to an Ubbelohde-type rheometer except that it is simpler in design and is less expensive. A schematic of an Ostwald viscometer is shown in Fig 3.6(b). It is characterized by a lower bulb that acts as a solution reservoir. A solution of known polymer concentration is placed in the lower bulb. A single capillary tube in which the measurement is taken is connected to the bottom of the bulb and to two small bulbs at the top of the capillary. Fluid is forced from the lower bulb through the capillary into the two small bulbs attached to the top of the capillary. There is a line between the two bulbs and at the exit of the lower bulb. The fluid is then allowed to drain back into the lower bulb through the capillary, and the time for the fluid to travel between the two lines is recorded. The time, if there were no end effects, is proportional to the kinematic viscosity (/j/p). 

Select a 250-cc. distilling flask A (Fig. 6) with a long neck and with the side tube as near the bulb as possible. Cut off the flare of the neck so as to leave the neck cylindrical to the very end. This is easily done as follows At one end of a piece of heavy iron wire (telegraph... 

---