A boiling tube, also known as a test tube, is a cylindrical piece of laboratory glassware commonly used in chemistry and biology experiments. It is usually open at the top and closed at the bottom, and it is made of borosilicate glass, which is resistant to thermal shock. Boiling tubes have a variety of uses in the laboratory, including: Heating and Boiling Liquids, Chemical Reactions, Storing and Transporting Samples & Observation and Testing Boiling tubes are available in different sizes, typically ranging from a few centimeters to several tens of centimeters in length. They are often used in conjunction with rubber stoppers or glass stoppers to seal the open end and prevent the escape of gases or vapors during experiments.