Science 101: The Function of Test Tubes
Mainly used in laboratories and classrooms, test tubes are vessels that hold and mix or store materials for use in experiments and research. There are several different types of test tubes available, and they may be made from varying materials.
Glass is the classic and most common test tube material. It's heat- and chemical-resistant. It's also easy to see through. Test tubes can also be made out of plastic, which is less expensive. Curious about what test tubes are used for? Here some answers to consider.
Test Tube History
The National Museum of American History suggests that Michael Faraday and Jons Jacob Berzelius may be the co-inventors of the test tube. The glass tubes first emerged in the early part of the 19th century. Earlier than that, research suggests that experiments were carried out using wine glasses.
In the early days, test tubes were made out of borosilicate glass — or Pyrex as it's most commonly known. By 1916, Pyrex was already in American kitchens. But the company also found it useful in laboratories. The superior strength and resistance against thermal shock, chemical corrosion, and mechanical stress made it a favorite among scientists.
Common Test Tube Materials
No matter what they're made of, most test tubes share a common shape. They're a thin cylinder with a round or flat bottom. Different materials have different benefits and strengths. Glass tubes are the most common kind. Borosilicate glass is strong and capable of standing up to chemicals and thermal shock. This makes it ideal for use in chemistry. Fused silica provides thermal stability. Quartz provides high infrared radiation transmission.
Plastic test tubes may be made from neoprene, which resists ultraviolet light damage. Nitrile works well at temperatures as low as -30 degrees Fahrenheit, making it a good option for low-temperature use.
Test Tubes' Laboratory Role
Safety and function collide. Test tubes allow chemists, scientists, and researchers to handle, mix, and experiment with materials safely. The heat- and chemical-resistant nature of the test tube makes it an ideal container for carrying out various experiments. Biologists often use test tubes to collect fluids, culture organisms, and hold samples.
They come in different sizes and are often held by hand or placed in special test tube holders. Some test tubes have caps or stoppers to keep fluids inside. Others have a lip that makes pouring easier.
Types of Test Tubes
Boiling tubes are made of borosilicate and are used for boiling chemicals
Centrifuge tubes are used to separate liquids and solids. They can be made of plastic or glass and usually have a cone or tapered design.
- Nuclear magnetic resonance (NMR) tubes are used for conducting imaging. This test tube is made of thin glass with a polyethylene cap.
- Test tubes with a rounded bottom are used in clinical medicine, bioscience, or chemical labs. They can be made of ceramic or metal, but they're usually made of glass or plastic.
- Thiele tubes have an attached, triangular handle. They're used for heating oil baths to figure out the melting point of substance.
- Thistle tubes have a long, thin tube attached to a funnel and reservoir. It's used to add liquid.