Thiele tube
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The Thiele tube is a laboratory glassware designed to contain and heat an oil bath, and is commonly used in the determination of the melting point of a substance. Its use has largely been superseded by electronic melting point apparatus.
Contents
General
The thiele tube has the form of a glass test tube with an attached V-tube. It is often filled with oil.
The Thiele tube may also be used to determine boiling points, by using a liquid sample instead of a solid sample.
How to operate a Thiele tube
- The clean Thiele tube is placed in a clamp;
- The tube is filled with oil up until near the level of the upper V tube bracket;
- The V-shaped handle is heated using a heat source, like an open flame;
- The shape of the Thiele tube allows for formation of convection currents in the oil when it is heated, which maintain a fairly uniform temperature distribution throughout the oil in the tube;
- The test sample is placed in a sealed capillary tube, which is tied to a thermometer using a rubber band or another binder;
- The thermometer is held in place using a thermometer clamp and immersed in the hot oil;
- During heating, the point at which melting is observed and the temperature constant is the melting point of the sample.
Availability
Thiele tubes can be bought from lab suppliers and online.
DIY Thiele tube
While you can make your own Thiele tube if you know how to weld glass tubing, a simple test tube can be used instead of Thiele tube. Just make sure to heat the oil from the tube slowly and evenly to keep the temperature of the oil constant.
