Other forms: test tubes
A test tube is a glass container used in a scientific laboratory. Scientists (and mad scientists) use test tubes to hold chemicals during experiments.
If you take a chemistry class, you might use a test tube to handle corrosive chemicals, or to mix two substances safely. Glass test tubes can also be heated to very high temperatures without breaking, so you can grasp them using special clamps and hold them over a flame. Historians aren't certain which chemist invented the test tube, although we know it appeared in the early days of the 19th century (before that, experiments were often conducted using wine glasses).