It is a device, made with nylon bristles attached to a twisted-wire shaft, used to knock the bottoms out of test tubes. Or at least it was when I was in high school chem class. It is a brush that is...
The test tubes are used to store or keep safe the small materials (such as hair) for later. Another example is (if you live along said river) at the "Hudson River Clean Up act" to test nitrates and...
The principal scope is to realize chemical reactions on a very small scale. Also: storing liquid or solid substances, solubility experiments, etc. A test tube is a cylindrical tube, made from...