Boiling tube
A boiling tube is a large tube made of glass, which is used in laboratory to strongly heat substances. A boiling tube is a scaled-up test tube, but larger in size. This larger size allows substances to boil freely inside a boiling tube.
Boiling tubes can also be used as a replacement for test tubes specially when a larger volume is desired.
Boiling tubes are commonly made from Pyrex glass which can tolerate high temperatures.
Boiling tube is also known as Hard Glass Tube