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EXPERIMENT NO. 1
TO CUT AND BEND A GLASS TUBE AND DRAW A JET
APPARATUS:
- Glass Tube
- Small Triangular file
- Knife
- Match Box
- Meter stick
- Glass marking pencil
- Bunsen burner / Spirit lamp
CUTTING OF A GLASS TUBE
METHOD:- Place a glass tube horizontally on a table (or any solid support) as given in the figure.
- Measure the desired length by the meter stick.
- Mark the length with a glass marking pencil.
- Make a single sharp transverse scratch with a triangle file at the mark.
- Hold the tube with both hands in a way that thumbs remain below (opposite to) the mark.
- Exert a little force to break the tube into two pieces with a quick jerk.
- Keep the tube away from your face.
- The tube breaks evenly at the scratched place.
- Round the rough edges of cut tubes by rotating in flame (fire-glazing).
- Allow the tube to cool by placing it over an asbestos sheet.
BENDING OF A GLASS TUBE
METHOD:- Hold a tube horizontally in your both hands over a Bunsen flame at the ptace where it is to be bent as shown in the figure.
- By rolling and moving the tube back and forth, heat the 2 inches part of the tube evenly, that has to be bent.
- Keep it rotating until it softens.
- When glass becomes soft.
- Bend it at the desired angle, keeping it a bit up from the tip of the flame.
- Hold until the glass hardens.
MAKING OUT A JET
METHOD:- Hold the tube in your both hands as given in the figure.
- Put it over the flame in a way that only one and half inch of the tube remains in the flame.
- Slowly rotate the tube about its axis, keeping it in the flame until it softens.
- When soft, remove it from the flame and immediately draw the two ends apart carefully till it forms a fine capillary of desired diameter.
- After cooling, cut the tube to separate the two ends by means of a knife.
- Round the rough edges of cut tubes by rotating in flame (fire-glazing).
- Each piece of the tube has a jet.
PRECAUTIONS:
- The scratch on the tubes should be sufficiently deep.
- Pressing of thumbs should be with a uniform force.
- Avoid too much heating, it may cause poor bends.
- The tube should be continuously rotated while heating.
- Do not keep the hot tube on the table.
- Pull the ends of the tube by taking it out of the flame.
- Heat the tube in the upper portion of the flame and continue rotating.
- While drawing a jet the pulling apart of the glass tube should be immediate and carefully.
- Never try to break the tube with simple bare hands.
Special Thanks to Sir Sajjad Akber Chandio
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