Cutting a glass dish from a used electric bulb

The hemispherical bottom of an electric light bulb gives a useful glass dish; a soldering iron can be used to cut it off. put the bulb on its side and make a scratch with a file somewhere with its line of greatest circumference. Carry the soldering iron at an angle of 450 in a laboratory clamp so that the tip is the similar height above the bench as the point of incision. Hold the bulb in both hands and, keeping it horizontal; bring the scratch into contact with the point of the soldering iron.