A Boiling Tube is a piece of laboratory glassware used to intensely heat substances in the flame of a Bunsen burner. It is small cylindrical vessel resembling a test tube but larger in size, about 50% larger. The design of a testing tube allows substances to boil rigorously as compared to a test tube, which is too narrow to perform such activity. Boiling tubes are made of borosilicate or pyrex glass that can tolerate high temperatures. Boiling tube is used as a replacement for test tubes especially when a larger volume is desired. Its wide open end allows gas generated during heating process to escape, which is not possible in testing tubes. .