Glass tubes, bending, 13 cutting

Experiment i.—Cut into halves a glass tube about 30 centimeters long. Bend one piece into a right angle and the other into an oblique angle. Submit each to the teacher... 

Insertion of a glass tube into a rubber connector or adapter or hose is easy if the glass is lubricated with a very small drop of glycerol. Grasp the tube very close to the end to be inserted if it is grasped at a distance, especially at the bend, the pressure applied for insertion may break the tube and result in a serious cut. 

Glass can be cut by making a single scratch mark on it with a file or knife. The scratch is moistened with a drop of saliva, the scratch mark placed upward, and the tubing pulled apart with a slight downward bending motion. The bottom photograph in... 

In this experiment you will cut, fire-polish, bend, and draw out small glass tubing. Although glass rod will not be used in this experiment, the same procedures can be used to cut, fire-polish, bend, and draw out small glass rod. At the same time, you may make a number of pieces that will be used in apparatus for later experiments. 

To cut glass tubing, make a notch in the tubing with a small triangular file and then snap—pulling and bending at the same time. 

Cut off the delivery tube at a distance of about 1.5 cm. from the neck and seal on a tube B of thin glass 1.3 cm. in diameter and 50 cm. to act as an air condenser, bending the tube as shown in the figure. Make a tube C shaped like a pipette the wide part of which will just slip into the neck of the flask. The lower end is of very small tubing drawn to a capillary at the tip. When the tip is almost at the bottom of the flask, the upper part of the narrow tube should be just above the outlet into the condenser tube. The wide tube should extend about 3 cm. above the end of the neck of the flask and should then contract to a short, narrow tube over which a short piece of rubber tubing, provided with a pinch cock F, is slipped. 

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